Kabab-Meister: Good work with the research you did on the subject. Your findings are consistent with what has become the golden rule in bicycle design, race car design, etc. Weight has an enormous effect on performance. I recommend you consider rotational mass if you want to push this further. In our case it means the prop, nut and bell. Lighter components here will have a measurable effect on responsiveness and acceleration. Rotational mass theory is: Two quads with identical mass. The one with a heavier frame but lighter props and bells will outperform the one with heavy motors and a light frame.
You are the king of nescience...but somehow I still watch and enjoy your videos. Engineers aren’t guessing or making theories based on incomplete data or guesses. We use MatLab and model performance based on science.
Yep I explain that over and over in all my videos these days. None of this is science. It's purely conjecture based on observation and likely 99% false
Interesting stuff. I used to race cars and it's interesting to see some scientific-ish rationale in favour of how the 'light weight is faster' rule porting over to quads. My own observations do tend to back up what's being asserted here as well...but not entirely. I think there's a big hole in this theory which is raw power + track type. Using cars as an example, the one (often only) place where a light weight car isn't as fast is on a long straight. On a track with enough long straights a heavier, more powerful car with a worse power to weigh ratio can claw back huge amounts of time against, and often turn quicker laps than, a lighter car which can accelerate, brake and turn better. What I'm getting at is that 'disc loading' theory may well be a very valid working model on tight tracks with lots of turns (think sub football field size) but I suspect that on larger, higher speed tracks (think football field size or larger) a more powerful quad would tend to dominate even if it's heavier, as long as there's enough of a power advantage. I think track size + power would be an interesting theory to test out given the huge variety of FPV racing tracks we see out there. The MultiGP Nationals track, Ibiza Euro Cup track, UK Nationals track and the Drone Worlds track in Hawaii were pretty huge, which is quite a different ballgame than stuff like the MultiGP UTT tracks or a lot of 'weekend' tracks that I see people flying typically. On lots of the shorter tracks I don't think many folks even hit (never mind sustain) full throttle very much, if at all, and I've almost never seen a big enough space where quads are able to fully wind up to, reach or sustain top speed. Personal observation from quad racing - disc loading theory would seem to suggest that I had better get my Lumenier Skitzo motors out again (super light!) even though in practice I've been blasted pretty badly by guys with more powerful quads while running those motors, even on tighter tracks. Could of course be piloting and not physics. Counterpoint to my own argument then - the really fast guy in my area (think top 20 or 30 in Europe) has recently swapped from his high kv setup back to old Cobra 2204 2300kv motors and started practicing with the intention of staying literally as close to 100% throttle as much of the time as possible. In that 'kamikaze; mode he's still usually quicker than I am but still measurably slower than he is on his ever so slightly slightly heavier 'monster' setup. Point being - I basically think track layout is a huge unexplored variable and I'm not convinced that we as pilots (in general) are consistently using enough of the full potential of our machines yet (think percentage of maximum available throttle and time spent there, maximum available cornering 'grip' and speed, etc.) to be able to say with much certainty how much speed is in the pilot and how much is in the machine.
The track layout and your car references do make sense however cars don't fly. You don't really have the ability to hit the breaks as you're flying and you can only drift so hard into a turn even if you forget about the next turn ahead. Tracks that are just straight shots back and fourth are dumb and pointless. Might as well just do vertical drag racing. I'd argue that yes, something heavier can overpower something lighter but that mainly comes down to component quality and power per gram of weight. For flying, you can't get away from weight. With cars, a lot of the time weight will help in the form of improved grip. Staying near 100% throttle also probably isn't gonna do it but moving towards lighter motors and generally lighter setups can. For a technical track, no doubt lighter will be far easier to fly. On a wide open track, you can fly anything but the lighter one will still probably win because it can get up and go faster. This is all still in its infancy. Lots more to come as we all improve.
This is just the basic law of inertia. You don't see semi's out-performing Ferraris on the track, nor do you see cargo planes maneuvering like F18s. Something light will always be quicker and more agile than something heavy. Applying more torque/HP on top of more weight only increases low-speed pulling power. On the same token, overall high speed can be increased with a little more weight. Adding weight can put inertia on your side as drag is inflicted upon your craft, but when we introduce drag to the equation, you also have to introduce aerodynamics and efficiency. It's all very complex, especially when we apply our thoughts to flying crafts. I think Kabab did a good job keeping the theory simple without diving into all the other tangents that apply to the situation. It's exciting to watch as the industry gets closer and closer to the "perfect" equation, and as more building techniques and materials are researched!
I really like this reply a lot, but I think extracting the right relevant information from it frames this whole setup a bit differently. The amount of time spent at wide open throttle on a car is going to be a pretty considerable portion of a lap on a big open track, whereas with a human pilot on a course, we're talking single digit percentages. The analogous place where that happens in cars is parking lot autocross, and if you look there lightweight and traction rule the day provided good piloting and no untoward behaviors of the car. Track layout matters a whole lot, but looking at where and how much full throttle happens, the time savings in a straightaway can be measured in tenths, while getting from the apex of a turn back to unloaded high speed adds up to seconds. I see a use and a need for the stouter motors in that they allow for a wider variation of prop setup (that can work well and be controlled across a larger range of loading parameters), and those will feel incredibly fast because they're moving lots of air and don't start to trail off at the top end. Then again, I'm quite new, and the guys I fly around out here can smoke most any mortal if flying a well-sorted turd, as such the courses tend to be pretty involved and precision oriented.
the42the42 I try but surprisingly this particular video has gotten a good deal of negativity. that's actually kinda interesting since it is an advanced topic.
After watching a number of your videos, I have to say that you do a great job of explaining complex subjects in a clear way. Keep up the good work, can't wait for your future videos. :)
Well, that is how it is with relatively new, complex subjects, unfortunately. There will always be those who buck against anything that doesn't mesh with their personal thoughts and ideas. Stay honest, it suits you well. :)
Nice explanation man :) That's more than likely what I experienced when comparing ulx or any quads around 230-250 grams dry against 300+ regardless of track and it seemed to handle turn and do everything faster. Almost to the point of brushless with no momentum carrying through turns. Acceleration etc much better. Nice to hear theory behind that :) keep up great work
7 лет назад
It's sure interesting to consider these sorts of theories, especially since different people have such differing ideas about how things work. For example, we have bulbufet talking about how little weight matters, how he prefers heavier motors because of their extra thrust, completely contrary to what you are trying to prove here.
Jay Anderson well I haven't seen that video, but I assure you that the very top pilots and racing quad engineers use this theory a lot. It pretty much defines how they build. heavy build is fine, but it has a lot of limitations. a purpose built quad is always the best performer.
Kabab, I love the fact that you analyse the physics of these quads. They're still new 'tech' so theres less hard and fast rules out there (unlike car racing), thats what makes this so interesting as a hobby. In response to a few of the hate comments- A small suggestion might be to label your theories in categories and sequence so anyone can simply check the latest 'theories' to save your rebuttals. Just a suggestion. Anyway keep em coming- loving your work
mikenxzz HyperLite Evo HD on the left, racekraft frame on the right. there is no top pick for 5" motors but some of my favorite ones are the HyperLite V2 2600kv
I came to the same conclusion some time ago. Two days ago I uploaded my latest designs on AP ,waiting for confirmation atm. One of this designs is a 4 inch 3mm that takes 1407 and 1807 motors, thats a 12mm mounting pattern.But this is not going to be super light at is it a freestyle form frame and should come at about 55 grams. After watching Brians video the other day with the insane 4 inch 1407 build I think I will do a simple stretched pod style in 3mm for 1407/1806 motors and 3d print an Aio camera mount. I calculate this to be a sub 180grams dry maybe even less with an fc that has a pdb.
Kabab FPV Thanks for bringing this up. Battery class is the greatest differentiater for race classes. It's like cc's in dirtbiking. Then open class needed. Separate events Acro VS. racing. Not sure on weight but seems right. I have 5s 4 inch quad that weighs 424 and 5s 5 inch quad 477. They are too fast to hit gates but interesting how much they fly differently. The 4 inch slices through wind like butter. 5s should only race in open class in my opinion.
Michael Steele heh, there's no such thing as too fast. those weights are not that light either so they could go faster. 5S is the highest end of the voltage sweet spot right now.
Top speed is MUCH more affected by DRAG than it is the weight of a craft. That's the whole reason a parachute works to slow down drag cars or the space shuttle for example. I was surprised you didn't even mention drag coefficient in your top speed portion...
You seem to be presenting somewhat contradictory points; if your goal was to reduce the disk loading number, it makes more sense to increase the diameter of the blade because that factor ( the radius) is squared, whereas reducing weight is a linear reduction of the disk loading number (depending on the weight and propeller sizes, I know for certain propeller sizes it makes more sense to decrease weight). For example, I have a quad copter running 10" propellers that weighs ~600 grams dry, and ~800 with battery, which would have a disk loading number of 2.54 which is less than half of the lowest value you presented, but obviously this quad could not compete. This theory may hold true within a set of bounds but presented as is, I do not think that it is valid. I do agree with your assertion that lighter is better in general due to reduced inertia. Lighter overall weight decreases linear inertia, and having lightweight motors, and centralized components will reduce the moment of inertia making the force that is applied result in higher angular acceleration. These two effects will result in better command responsiveness.
Sean Burke yes! you are correct! but as I keep saying to everyone, this estimation leaves out a TON of details. I also discuss how I give the heavier quad that's 5" a handicap over a lighter 3" even though the disk loaded number is less because it simply has more inertia to haul around. this is what you're sending with the bigger prop areas. also, note that all racing quads in the 1000 class will fly around like a super light. they'll just have more inertia...
Bob. We have never met before which is why I am surprised you would give me an early Christmas present like this. Or maybe it is a late Christmas present. Either way, thanks...Great video!
Catalyst Machineworks lol you bet. but if you read the comments up, you'll see that I've been getting more negativity from this video than any of my other ones. also many have messaged me on FB to tell me I'm full of it. the concept is over many people's heads. we can only lead a horse to water...
and this is why my light 4" quad on 5s is such a beast! When I told them my 4" on 5s is faster than my 5" on 5s they all just don't believe me/ understand. it's nice to have some other more technical description of why this is.
My Fu-Rc Kore build has 2306-2700kv and is about 320g dry. I mostly built it for to speed and run 2 blades on it. This video is making me consider putting 2206-2300kv on it so I can go back to an avan-r. I'm so torn, thanks kabab...
The avan twin requires a really powerful motor. I wouldn't bother on less than a 2207 or 2208. I know it was made for 2306 but I haven't had good results (at all) with it on a motor of that size. I would recommend APC props for speed runs.
Kabab FPV 100% agreed the avan twin sags my battery hard and has no grip. The gemfan 5152 twin on the other hand was a revelation. Thanks for the reply.
Weight is also much more of a factor on a track with a lot of turns. If it's a massive circle or an oval, weight plays almost zero effect and a more powerful but heavy setup will win every time. The more wide open, larger and less turns a track has the less that weight matters and the more that drag, prop terminal velocity (peak rpm) matter. A light quad crappy powered will suck on a huge wide open oval track! None of this is new, it's is applied to many other power sports we have been watching for years. :)
Eganwp I would argue that this is not true. the light quad will likely keep up the same and will be able to do more laps due to its better efficiency. even in an oval track, weight matters. your mass is being flung out of the circle. you gotta pull it back with something. it doesn't just stay in line. top speed, as I said, is another story.
Kabab FPV I disagree. If that were true then the Reno air races would be won by the lightest smallest engine planes (to save weight), and it's not. Its always the most powerful plane with best consistency and piloting skills. Same with NASCAR. If lightest always would win the oval, why wouldn't the pace-car win the race assuming its lighter? Lol. Yes lighter is always faster, but you can't just assuming lighter and lighter always beats more power. If that were true then a bee flying should beat nascars around the track...
Eganwp well of course it's the pilot that wins the race. multiple setups can do the same thing too. I would simply just choose the lighter one in most cases.
In my experience, geometry and air resistance is king, then props, then weight, then power. I have built over 9 different frames and the ones that are my favorite have one thing in common, they sound quiet in the air. One of my faves was an aimdroix blackbird, a heavy skinny arm quad with bi-level motor mounting and stretched H platform. The air going past the props was clean and although heavy, it was fast, stable and smooth, I took its guts out and built a Shendrones 5" X, it was 80gr. Lighter, but it flew like crap due to the short wheelbase, I could never get that locked in feel. Yes more weight means more momentum, but the FC doesn't care, if anything heavy builds are easier to tune. I'm not recommending pigs, but I know first hand light isn't always better and heavy isn't always faster- but clean geometry is always a must for good performance. Im currently flying stretched cross frames and never looking back to X.
Also, you show a very tight track, obviously a lighter, smaller quad will win, but on a big open track, the larger quad will dominate just like a Miata Vs. A Viper.
Have you flown a stretched + with recent firmware? They lean more into turns and carry more speed with them as well, current betaflight firmware runs very well on these frames. They feel weird, yes, almost like a flying wing that can turn on a dime, but, stability wise, for me at least, I get zero prop wash and artificial feeling flips and rolls, it will also carry speed and bank like a sport bike and slice up the air.
It's an interesting Theory but I find it to be wanting in detail. My first thought is that two propellers of the same disc size can easily give different thrusts and have different weights. So that when you put them on the same motor one prop will have higher maximum thrust but will create more drag and therefore not allow the motor to spin it up to speed as quickly or with the same amps. In addition a blade that has one blade versus a blade that has three or four or five each blade is creating more drag but not proportionately more drag. Take a 2 blade prop versus a 3 blade prop with the exact same blade Dimensions including pitch and line and area. The 3 blade will not produce 50% more drag than the two blade prop. but likely will generate close to 50% more thrust. Something to do with the propwash from each blade being closer together as it passes through the air.
The Theory doesn't even take into account the number or dimensions of the blade of each propeller. However that would be irrelevant when all you have to do is calculate the thrust that one motor and propeller combination can generate with a given voltage. Compare that to the weight of the quadcopter and you should be able to calculate your acceleration rate. And as a quadcopter turning in a corner is equivalent to its thrust to weight ratio capabilities meaning when it goes through a corner in order to turn tighter it will have to slow down more there is a minimum turn radius at maximum speed for any given quadcopter to reduce this turn radius at a given speed you must increase the thrust or decrease the weight
Hi Bob thanks for the interesting video...I might try a superlight build...how much does the hyperlite evo 3mm arm weigh? I couldnt see that detail on the pyroflip site...
With battery voltage being a determining factor for class, I feel like for a viable 6S quad you need to reduce the motor KV to the point that you may as well just use 4S and high KV motors. The only advantage I see with 6S is lower KV motors, which means less current, so smaller wires and ESCs, so you could save a little weight.
Adam Wilkinson 6S is a bit much weight. also, on a light setup, 6S is no big deal for the motors. Ricky runs 5S and 6S on the light quad and it doesn't even get warm. he only uses XM20 ESCs. 5S is far better than 6S however. has the power without that much added weight.
I'd assume you'd want to keep the weight about the same, so 1.3Ah*14.8V=19.24Wh 19.24Wh/22.2V=0.866Ah, so you'd be looking for maybe an 850mAh 6S to keep it similar. But my point really is that you can have a similar performing quad at different voltages. So, 2300KV*14.8V=34040RPM, 34040RPM/22.2V=1533KV, so if you have a 1500KV motor and a 850mAh 6S battery, then it's the same as a 2300KV motor with a 4S battery right? And by that logic, if people are running 6S on 2300KV motors, then why not just use 3450KV motors on 4S?
Adam Wilkinson while this makes sense, you're missing one very important aspect. the torque added of higher voltage. you simply get loads more torque. this torque improves all aspects of flight. past 5S is no help however. you're getting too heavy then. a superlight 5" on 800ma 5S is too performance right now on planet earth. like an 850ma 5S on 5.5" would be better but those components don't exist yet.
Thank you for this video! very informative. I wanted to argue everyone's point on a heavy quad going faster so bad. physics just doesn't work that way. inertia and wind resistance are our worst enemies!
Am I the only one having trouble following this? I mean, with all the corrections in the description, the overlayed text correcting what's being said, the admissions that he was completely wrong in the last video theory, and the constant reminder of "over simplification" is there a reason anyone should take what he says seriously? Just seems like a bunch of confused nonsense.
Verbal Tease I'm sorry it may be a bit confusing. I present information when I feel like I've matured my knowledge of it. the last video of heavier quads was a joke and just a rebuttal to Stu and Josh. I also didn't properly think through what I was saying so it wasn't fully correct. this video however is. I will try to be more cohesive in the future.
Kabab FPV If your goal is to present a theory based on science, present it methodically, as science is supposed to be presented. If you want to state opinions based on subjective experience, that's totally different. The first way doesn't require any trust or confidence because you're giving facts. The second is normal blogging; entertainment without much substance. I have an interest in quads and the theory behind how they work. Watching you ramble on for 16 minutes was disappointing because I thought it could have been stated much better in a fraction of the time. I appreciate the sharing of information, just wish it was structured better. Thanks for reading my feedback.
Kabab FPV If your goal is to present a theory based on science, present it methodically, as science is supposed to be presented. If you want to state opinions based on subjective experience, that's totally different. The first way doesn't require any trust or confidence because you're giving facts. The second is normal blogging; entertainment without much substance. I have an interest in quads and the theory behind how they work. Watching you ramble on for 16 minutes was disappointing because I thought it could have been stated much better in a fraction of the time. I appreciate the sharing of information, just wish it was structured better. Thanks for reading my feedback.
Verbal Tease I agree with your general assessment of this video. using the method of writing notes to cover made it more cumbersome than it could have been. I won't do that again. I'm still just learning. I also have a real job and just do this for fun because I enjoy teaching what I've learned and discussing. there is little science being presented here as you can tell. nothing follows any scientific method other than observation. I'm still just getting used to making videos. I'll try to improve in the future. these videos presenting complex ideas are far more difficult to make.
Great info! Appreciate your time and energy in putting this stuff together..QUESTION- I saw Brian's 4" with 1407 motors, what 4" frame has motor holes for 1407's?? He cuts his own frames so easy for him..I haven't found a 4" that you can mount 1407's on.
There are only about two on the market and I'll be making one as well however as I present in this video, a super light 5" is gonna perform better so I'm focusing on that.
I've been playing with many designs but I just can't get them to the weight I want. It's most likely gonna be just an elongated 3" to fit the 4" props.
Very interesting! I might mess around with that math equation myself and see what I can come up with. There also seems to be a dearth of 2204 motors on the market. Though that shouldn't be all that surprising I suppose. After parsing through MQTB for oh, 5-10 minutes, the lightest motor I could find was the RCX SE2205 (A bit surprising honestly) at 25g. Though all my motor info comes from MQTB, so I'm sure I'm missing something. With that tangent out of the way, great video as always! I'll be sure to pay closer attention to this stuff in the future.
Thanks for the video, very interesting to have new variables and theories to consider. I know there are no absolutes, but what do you suggest as a target weight for a 5 inch 2600kv copter, mostly used for acro? I had been going for 1500mah batteries, but maybe I'll have to switch to 1300's on my next purchases.
Kabab FPV you might be interested to know I was thinking along this theory as I was asking about the 2520kv , my alien with HD cam is like 680 grams , I'm a race car guy and that weight turns my stomach, my new build with camera battery everything will be just under 500 grams,that makes me happy😁 good video
Hello! Great video and Channel. I was wondering, what was the setup on the superlight quad in the beginning of the video? I wanted to test to build a superlight quad and im struggling to get down below 250 at the moment. Thanks!
Your Videos Are awesome But One Thing everybody seems to blend out is drag and surface area. I calculated that a quad with 50% Less drag could reach about 30% more top speed with The same thrust factor. This came to my mind after i maidened my iFlight ix5 and felt it was going way faster than my other quad with same Motors But more surface area
Tourensohn MotoVlog sure but on an ultra light, the arms are already only like 6-8mm wide and the body is as small as physically possible. how else would you like to reduce drag? particularly without adding weight. I'm not concerned with heavy acro setups. that's a whole different thing. also, this little ultralight already does 90mph on 4S. how much faster you think you could go on a track ? they're usually not just wide open straight shot.
Are races regulated nowadays such as weight, prop, motor, battery and frame size or is it still bring what have and you can enter the race? Do you think this hobby will be regulated like all the other rc genres or is it still too new of a sport?
Great video Kabab, I just thought that you would be interested in a post just made by QuadMcFly via RcGroups where he states that there is a lot more than you're explaining, and that what you are explaining is only a piece of the entire puzzle as a whole, just wanted to know what you make of it: www.rcgroups.com/forums/showpost.php?p=36926229&postcount=3268
I talk to Ryan about a lotta things often. He's one of the very best sources of information. That is a fantastic post that I didn't even know he wrote. I've been trying to convey all that in some videos but it starts getting too long with examples or too confusing. Text is really better for this kind of dense information and he did an amazing job.
Kabab FPV Hey no worries brother, he just posted that reply tonight after I shared your video in the motor performance thread on RcGroups, and wanted to know his thoughts on the matter since we have been discussing the subject further, to include fluid dynamics and physics of the models we fly. Keep up the great work man, you're doing and explaining more about the technical aspects of this hobby than 95% of the people I know and follow, which is commendable 👍
I'm very happy to be stimulating discussion and thought but I can hardly begin to live up to the work Ryan has put into it. If I was to name anyone the most knowledgeable about this sport it would without a doubt be Ryan. Then maybe Brian Morris.
Watched the whole video and you present some very interesting theories. Not to take away from any of that - but there's something very wrong with the left hand quad in the head to head at the beginning if that's as fast as it'll go. Me and most of the guys I fly with have 5" setups of similar weight to that and that thing looks like it's being flown at half throttle.
Yes it is the fast it will go. Ricky is a crazy fast pilot. You really need to be a world class racer to beat him. This track requires a lot of direction changes. Anything with a little weight is gonna suck at that.
Kabab FPV I fly with a bunch of people who competed in the Hawaii world's and they all fly setups closer to the left hand setup than the right hand setup. Their quads all go much faster than the left hand quad, even on a track such as this. That right hand quad is fast, I'll give you that, but I don't think the left hand quad is a good representation of top end performance you can achieve with a quad of that weight.
I was just told by the track organizer that before Ricky's light quad, the track record was set by a 324g dry weight quad and it was 26 seconds. We in CA are definitely not slow pilots. Ricky is literally one of the fastest in the world as are a couple others down here. The light quad did it in 20.8 seconds and that time was far more consistent than the heavy one. He can also do two additional laps than the heavy quad on a battery that's 30% smaller.
Kabab FPV definitely not arguing that heavier is better, just that that particular heavier quad seemed slower than others of similar weight/setup. But hey, you're the one with DVR and lap times, I'm just saying 'it seems slow', haha. In any case, I appreciate the discussion and your interesting videos. Cheers!
I agree. When I first saw it I exclaimed that he was just cruising too. He wasn't however. The thing just can't carry its weight through the track that quickly. Can't get on the power and make it around the next turn.
There is a sweet point. Too heavy = bad Too light = bad Find the happy medium with your quad The heavier one is better for a less experienced person and the lighter one is better for a "pro" because going around corners with a light quad will be harder.
What about a theoretical 150g 5" quad in turbulent air? Generally lighter is better though, but at some point we are just measurabating instead of flying.
Are these "notes" from lumenier company ? :D I guess so. So here we are. If you are right, why so many pilots using lumenier lightweight motors (whitch are basicaly only 22g +- 5inch motors on market) arent on first places all the time ?
Jan Prejzek I'm sure they're using these calculations. it's why the skitzo motors seem so crappy. they just didn't tell us how to use them. they're actually excellent race motors if built right. they're just way too expensive to use for anything. I believe this is also why skitzo was testing 1806 motors a while ago. those motors never came out however because he public doesn't properly understand concepts like this.
I'm optimizing frames since a year, because i was not rich enough for all those new hyperlite motors and so i kept my 2204 :) a shame i sold yesterday my sunnyksy 2204 2300kv (21g) for sunnysky r2205 2500kv (33g) - two things i noticed was the extra weight of 40g - the difference is most noticeable where the drone have to change the direction abrupt. secondly my 1300mah lipos have too little capacity to live more than 2 month with those monsters. the R2205 are faster at the top end no question. but if you have to change your direction 40 times (which is normal for a race) it would take longer each turn to recover the extra weight. but a 2205 has the power to compensate my action cam, which a 2204 does not have. thats why i am not soo sad about it. however: i was not really interested to this moment to design a frame for 1806 or 1406 motors, but now i will. there it not much to save weight except - motors x4, battery, esc x4, frame (in that order) - the rest is secondary. i designed my first frame with hole in the 3mm arms, to proove that RCmodelreviews was wrong. however - i sell them since a year and nobody was able to break them. keep your direction. you do way more professional than others.
No need to complicate things. Physics is simple. Second newton's law "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. (F=m*a)" It all comes down to the race track. You need really high max speeds or you need a snappy quad? In a tight race there is no point to have a quad that can reach up to 150km/h but needs time to do it. It's better to have a snappy one that reaches 100km/h or even 80km/h instantly.
There is probably a sweet spot. Too low disk loading, and performance may go down. Haven't given it too much thought, but with skydiving ram air canopies, wing loading is taken into account and people shoot to aim at a certain sweet spot to get the best performance from their parachute (wing).
Matt Brozyna well yeah that's a totally different story. there isn't really a too low for spinning blades. for a parachute you need to have a counter balance for the parachute to stay open.
DanutsFPV I can't seem to say it enough or people just skip through it. I'm actually getting a good deal of negativity to this video. more than my other ones. people think it's hype....can only lead a horse to water. I guess there won't be a wave of people moving to super light super fast quads. that's fine, easier for the ones that understand to win.
very interesting thanks for the info ive done a 4inch build weighing in at about 255grams but the motors are the new rs2205s 2600kv red bottoms, what would be a good motor if i was to go to a smaller motor? im uk based so nothing that is in the states lol
got the rfx160 so its perfect just ordered these and will switch out the motors and see what happens with bullnose tri blades? (4inch) thanks for the advice too
So would a quad that can run 6" props and is also light (330g dry) run better on 6" props than it would on 5" props for racing? Just wondering in terms of speed and cornering, flying 6" feels a lot more floaty to me.
15inch quad would need to spin props at 25k for 70mph i don't think so mate. Not unless your running a 15inch prop with a stupidly low pitch. Remember that the tips on the bigger blades have a much higher linear velocity which would generate a higher thrust speed for the same rpm on a smaller blade with similar blade angle.
This is all very relevant info, however....dare I say 95% or better, of this sport is skill. I wish there was as much time spent on flying techniques and strategies. I would like to see this much attention spent on finding the best lines to fly on a course. start strategies. gate aiming. and everything else that is relevant to improving . I do get a lot out of these quad theories, and the nuts and bolts videos. but I would like to challenge the video gurus to make more flying Technique vids.
This is the same pilot that's as good as any pilot right now which is SIGNIFICANTLY faster on the lighter quad and more consistent too. That says a lot. It's one of those things that more and more people will realize as they improve. That being said, I can talk about racing line all day but what's the point if you can't execute? Flying technique is mainly just practice. You learn to carry your speed through turns by doing little dive maneuvers naturally. Here's Shaun Taylors strategy. Get out the start extremely fast. Stay in first the entire time. If someone passes him, he gets all messed up. Good for him that he's really frikin hard to pass. Here's another strategy, let everyone else go first and expect them all to crash...
TransAm2k4 with a disk load number of about 5, it's definitely more agile than a heavy 5". can't dispute that. but as I keep saying in the video, this concept is hugely simplified.
So you're saying to run 1806 motors with 5 inch since its lighter? This theory has quite a few flaws in it. There is no linear relationship between performance and weight, it's definitely waaaay more complex than that. What would be far more valuable would be to plot the thrust to weight ratio across the entire throttle range as well as the Grams per watt that is being output. What determines how well a quad performs is its throttle response not its peak thrust to weight otherwise everyone would run high kv with bi blades. But the lightest quad for a given prop size does not give guaranteed increase in performance or a 5 inch with 1806 or even 1407 motors would outperform a 22xx motor with 5 inch props simply because it weighs less by your theory which really doesn't make much sense.
MewoFPV this is an entirely different discussion. I'm just presenting a way to quantify performance across weight classes. of course you can't run 1407 motors with 5". but as I said, that's a totally different discussion. this calculation is what the top pilots in the world use to decide what to build...it's an advanced tool.
And to go further to say that weight is the only deciding factor would be to imply that choosing a motor that weighs 1 gram less than another and outputs 700grams less peak thrust would be a faster quad because thrust doesn't matter...
MewoFPV First off, I keep saying in the video that it's super simplified here. next, Shaun Taylor runs the Hyperlite 2206 2700kv on gf5045 twin blades for racing. he does not build super light stuff because his crashes are pretty tough and even he doesn't like fixing everything all the time. for actual racing, he probably flies his lighter setups. also, I'm saying that yes, on a technical track, the 1806 5" would perform better. on a wide open tracks, a 2204 5" would perform better. on an extrmely wide open track, a light as possible 2206 2700kv could probably keep up with the 2204 equally. there's also the GoPro to take into consideration. if you're planning on carrying one, you absolutely need the thrust so must build heavy. this theory that I represent is extremely simplified. as I keep saying in the video. take the idea and use it. it's not an absolute and I haven't quantified even 2% of the real world into math here. also, if you think the theory is incorrect, I would actually love to see a video where you build an 1806 5" that's 190g dry and race it against a 450g super power build yourself. I think you'd be quite surprised with your findings.
Yea I just thought the example you used was pretty misleading. You compared Ricky flying a 335g dry quad vs a 224g dry quad and emphasized his use of old lighter motors made the quad faster. The motors don't account for more than a 20-25g difference so he's flying a totally heavier quad. I'm afraid your data will mislead people to take something like hyperlite v4s off of their quad and replace them with like Cobra 2204(5)s to lose 20g and wonder why their quad is way slower. Even considering it's oversimplified, any application of your claim would not be consistent with the effect you'd imply. I have light warpquads that have old 2204s on them and they're slower in every way than my 300g quad with 2206s.
pretty interesting stuff.......i have a set of the piroflip motors 2204 - 3050 kv and it screams on the dal 4045v2 props...i run 1000mah lipos ...its a touch heavy ...285g without lipo.
Similar. The kV isn't really that important but on a lighter quad, it actually can move quicker and take advantage of the higher kV. Still the effect isn't enormous and your balancing how many amps the battery can supply. I'd say you really don't need anything beyond 2500kv on any setup. For 5", less than 2100kv can be slower however.
There's a LOT that's missing from the equation. The way the pitch works is that the heavier quad actually needs less pitch since it can't make use of the steep pitch. This is likely why all the top acro pilots seem to prefer the flatter 4 pitch too although the butter cutter prop is doing well. I'm not sure it's actually a 5 pitch however. The lighter quads will work way better with a steep pitch. This is likely why matty stunts likes his super aggressive DAL 5x4.5x3 HBN props (which are really some of the worst props ever made for a number of reasons).
JulianGoesPro he's told me how he won't fly anything else. I'm not against RF but I haven't been particularly for them in the past. if I received some test equipment I wouldn't turn it down but I have no reason to try something else right now. Betaflight is working really well for me. in the past, RF has tried to kill me a few times with random quad reactions. also cost me a number of burnt motors. I've been scarred...
Gino Poe I've wanted to but I think I'll actually piss off a whole lotta people with it. the mifune is not actually faster. in fact it's most likely slower. I'm pretty sure one of the most aerodynamic frames is the helix. I guess I'll attempt one and try to make it not so harsh on the topic.
you have covered the issue of weight, now how crucial is aerodynamics? This is what Mclaren have to say (regarding bicycles) "The McLaren software also makes it possible to adjust any parameter to see how a change affects performance. My 56cm ViAS weighed 16.9 pounds, which is heavy relative to climbing bikes. So I asked the engineers how much gain one would make by cutting a few pounds. A quick calculation revealed that cutting the weight by 1.9 pounds (bringing the bike to the UCI limit) improved the 11.9-mile time by 3.2 seconds-that’s paltry relative to the 120 seconds gained through aerodynamics."
Gino Poe yeah aero is important but it's not how you would imagine for things that fly and are primarily just props. I'll put together some graphics and thoughts to present. thanks for reminding me about it. I personally believe weight is more crucial than aero.
go harsh, for more dramatic effect and response. Its funny, we fly these "aircraft" but i havent seen a video on aerodynamic comparisons with drag co-efficience and lap times etc... yet the current design of quads is dragging a single flat plate across the air, i guess its acceptable in 2017. the only quad i have seen is the DEBRE which focuses on reducing front profile but i dont think its going to production. I would be good to see more focus and radically aerodynamic designs come out to compare its benefits.
It does have an impact but I don't think it's huge and the main issue is that adding weight to improve aerodynamics takes away from control and agility. We also don't have air brakes so I feel like the drag isn't a horrible thing. Especially on superlight setups.
? what about it? If you want to race with a gopro, I'd recommend a 6" build. The issue with 6" is that the props are not durable at all. So you're stuck with 5" and poor performance due to excessive disk loading.
thanks for the reply.....i think the conclusion is high spec with more weight is not guarantee win the race than low spec but superduperrrrrrr light...
dude your theory could even be true but the DVR of both quad cant be compared. The quad on the sx commits error while the other one is smoother on the cornering. 7sec on a 30sec circuit is not normal.
Right the 1804 would be good on 4" but the 1308 would be a bit over driven I think. The recent 1407's are really well built and super powerful for their size however.
Kabab FPV I've changed my opinion. The tmotor air 2205 motors weigh 21g with short wires and are lumenier smooth. You just have to epoxy them to the frame so they don't rip off mid flight and you're good to go or fly with 4 screws. I'm not buying anything else for a while now though, I'm going to just fly 6s because its amazing.
Kabab FPV I think if the escs accepted it and more people had higher cell chargers, people could fly 7s or 8s like no joke. I can't tell a heat difference between 4s and 6s, maybe the battery. I ended up making some lowrider zmr with the battery perfectly level to the props and it actually flies better than my 185 terrible shakey x banggood frame. I couldn't believe it. You probably reply to comments all day because you got like 3k subscribers in the past month. And I see how if your changing the hobby this much.
Take an imaginary motor of a 0101 and let it = 1.0. Torque increases at r^2 and linearly with height. Radius calc is 18-01 = 17. 17/2 = 8.5mm which is the difference in radius so 8.5^2=72.25. The stator is 4x taller so height difference is 4/1=4, so multiply these two together to compare torque to the theoretical 0101 motor. 72.25*4 = 289. Doing the same for a 1308 = 36 due to radius and 8 due to stator height which total 36*8=288. 289/288 is = ~1 so and 1804 and a1308 motor should produce about the same torque for a given power. A 1407 = 6.5^2*7=296. 296/289 = 1.02. A 1407 motor should have around 2% more torque than a 1308 or an 1804. You can calculate power density from this to figure out what motor gives you the most torque per gram :) This isn't exact, but it gets you in the ball park.
Speed is basically dictated by aerodynamics, rpm and pitch... weight doesn't really matter. Speed is not acceleration. Weight has a big affect on acceleration but very quickly air resistance dominates everything and weight no longer really matters. A 1kg and a 10kg object of the same shape/size have the same air resistance. Presumably the heavier object will have more power though push through air, making it faster.
+Kabab FPV I went for an ultralight build using your hyperlite frame and came out at 238g dry and 350g AUW with a 900mAh lipo rotorbuilds.com/build/2873 Thanks for the idea ;) (edit 4g mistake on the weight)
Wow that is definitely the lowest weight I've ever seen. And I just saw 250 a few days ago and thought that was amazing. How does it perform? That thing will definitely never break the frame. The frame is far too much for that kind of setup. I should be receiving my new sueprlight prototypes some time at the end of this week. Would knock another 30g off your setup. Definitely sharing this on the Hyperlite FB page. Really nice write up.
Thanks for the kind words. To answer your other reply the motors are 25g with the longish wires they come with, and I still had to lengthen them to reach the center stack. Frame came out at 69g with the hardware needed to mount the fc. I haven't had a chance to fly it FPV yet, but test hovers in the backyards tell me that thing will be suuuuuper reactive! Can't wait to try those ugly brown hyperlite motors when they are in stock haha
Yess i always stongly believed lighter is better 😎😎 and now there are numbers 😁😁 (its funny becouse the people i fly with are always wondering why i can almost fly a minuute or more longer on a 1300 then they can, and then i say: well i am 150 to 200 grams lighter. (This was already happening last summer)) so this video makes me very happy 😁
Based on your video i started to make downgrade my race setup to 21g motors: facebook.com/skullndrones/ - check out the latest video. The agility boost is insane. Even with 1300mAh Lipo. (Tattu 75C reduced to 142g) - the AUW: 400g With this setup i made a 1/4mile race against a hyperlite 2206 on a stretch setup (AUW 450g) - with the same times. Around a tight course he had no chance. Next step - carbon frame, 4in1 esc and micro camera. Thanks for your inspiration!
Btw there is some non existing motor with 25g weight (between 22 and 28) ,-) if someone interested. rotorgeeks.com/index.php?route=product/product&product_id=396 Sorry Kabab
The Hyperlite/ZMX V2 2205 motor is the same weight and much higher construction quality in terms of power output so those motors were obsolete before I even knew about them. I also have my own 21g 2204 prototype motors on their way to me in a week or two with much more modern and higher build quality. Very early on Rotorgeeks screwed me for no reason. Sent me some faulty ESC's that ended up destroying themselves and the motors with them. They blamed it on me and said I didn't bench test the components enough before flying (which is a ridiculous thing to do. Nobody spends a day bench testing before flying). David Klein, the owner, reluctantly half apologized to me over a year later but it was quite possibly the most negative customer service experience I've ever had since they were basically telling me I'm absolutely wrong in multiple emails and I didn't provoke such a response. I still have the emails and David is now aware of me. David cannot even give a customer an honest 'sorry for bad support.' Rotorgeeks is not a shop I would recommend to anyone despite good experiences others have had.
Yea, it is littlebit about time when mentioned motors come on market ,-). I saw these Hyperlites V2 too yesterday. Obviously sold out as many other motors on that webpage :))
How about those Air 200 2205 - 2650kv? www.miniquadtestbench.com/t-motor-air-200-2205-2450kv.html At 23g (21g) on short wires they could be a winner coupled with HQ 5X4X3 V1S (3.5g). Amp draw should even be low enough to use a KISS AIO CC that caps out at 21A. Now if only your hyperlite EVO frame was in stock... :D Nice video!
I pretty much won't run any motor more than 24g anymore on anything I intend to race. Acro is whatever. Totally different story. As long as I have the power to pull out of a dive easily it's fine.
Oh sorry; the term profit has taken on a different meaning in internet culture these days. Profit in the terms I was speaking in mean " gaining large amounts of benefit after the sum of all the parts come together"
I'm so confused by this almost combative tone you have taken in response to Joshua Bardwell's and UAVfutures videos. If you really wanted to offer a real response to them you would address the benefits of stretched vs. X vs. wide layouts as this was more along the lines of what they were addressing and might actually further the conversation. That you've gone so far off topic is just an indication that you almost entirely missed the point of their videos. Neither of them were arguing that properties of physics, fluid dynamics and the disk loading theory that you have presented would prevent a smaller/lighter quad from being able to move around a track faster or have a higher top speed - *in theory*. They were simply expressing why some *flight dynamics* make it easier to PILOT these heavier quads with faster track times - something you have almost completely glossed over. You also focused so hard on Joshua's use of the term "camera uptilt angle" which is indeed a confusing term when all he meant (and was clear from his video) was something more like "frame tilt angle" ... but camera uptilt angle is somewhat of a proxy for this. They were very clear that what they were expressing was an optimization of a pilot's skills and flight dynamics not the theoretical limits. For instance, Joshua's response was, in my mind, an excellent response to UAVFuture's video because it attempted to add a quantitative response to a qualitative observation ... you're making interesting videos ... they just really aren't relevant to either of the ones you're responding to. I assume the issues they refer to will ultimately become irrelevant as more racing specific PID profiles/logic are made to take this into account and then the theoretical limits you're chasing after would become more important. I feel like, at some point, racers are going to need another means of controlling their quads... like foot pedals for dynamic pitch rates or something wacky like that - a means of maintaining ultra fine altitude control at extreme angles but being able to unlock that for tracks that require large vertical changes at varying speeds. QuadPedals(TM)
CesiumSalami this video was NOT a response to them. I said my last video that WAS a response to them was incorrect about many things I said. nonetheless I will make another video discussing what you say because it seems many did not understand
CesiumSalami multirotors are hugely unlikely to move toward collective pitch. that's just not how these things work. we already have CP helis and quads. they're a different category. I'll discuss my very small opinion about that as well.
That's fair. My apologies on perhaps adding to the frustration. I just had that video on my mind, I guess - which is a good thing. Getting people thinking that is. Thanks for the response.
@Kabab FPV - Oh. I don't mean adding any additional moving parts to the quad that actually control the pitch / angle of attack of the blades themselves - collective pitch doesn't really make any sense on a quad for sure ... I was referring to a control that allows the user to vary the rates on the pitch axis. Basically, the harder you pitch the quad forward at speed, you're effectively increasing the rates on your pitch axis (the quad becomes very touchy and overly responsive). During fast forward flight a pilot might benefit from turning down their rates but that would be detrimentally for certain maneuvers, so you leave your rates high. The extra control i'm talking about would just be a mechanism to change your rates or increase your expo dynamically and quickly. This would allow a user to, during extreme forward flight effectively increase the expo to allow for really fine altitude control but then back that off when larger variations are required. This would be software based entirely.... It would just be like a SUPER complicated and dynamic expo curve that responded to speed/tilt angle.
That would be very complicated and I feel too unpredictable to manage. When you're flying at a normal pitch of ~60deg, it's already less sensitive to pitch adjustments actually. Also, what you say would work if we had batteries that could sustain high amp draw. Without that, we can't keep it going forward like a set of wings can. I do however understand what you're saying. Maybe someone will invent some algorithm in time that will be able to manage what you say in a predictive manner. That being said, in order to sense angle with respect to anything, the accelerometer needs to be turned on. Accel sensors are not as fast as gyro sensors which will require significantly reduced gyro rates. That will hugely impact performance. Maybe the accel sensors will improve in time to allow this or someone will decide to put one outside the loop for just low rate sensing.
motkoloko you could go ahead and just read the Wikipedia on the "Disk Loading Theory". note that it's labeled as a theory. this video is also NOT scientific. none of my videos are. I wish I had the time to do real science...
Thank you for this video! very informative. I wanted to argue everyone's point on a heavy quad going faster so bad. physics just doesn't work that way. inertia and wind resistance are our worst enemies!
Kabab FPV true. but the future of the sport is freedom class and I know that doesn't have anything to do with this particular subject but when you get into a larger quad the wind resistance starts to affect it more and more. As we scale up aerodynamics start to play a huge roll.
Yeah I'm working on that actually. My preferred frame design is actually a huge hash tag pattern octo because it's super easy to repair and it's an octo so smaller blades spinning faster. The issue is that 8 sticks moving through the air is a huge aero issue...but it's highly repairable.
But isn't that going in the opposite direction implied by disk loading? Among rotary craft (no gliding), for endurance-per-gram, nothing beats a 1-rotor (straight up heli), because the r is squared in (PI * r^2). [OK endurance/heavy lift is not exactly relevant for racing, doesn't say anything about agility, but it exactly proves disk loading.] PS -- congrats on your Evo HD frame winning Sebring for MAD_AIR. I know you know more about all this than I do!
Kabab FPV that sounds like it would have amazing authority in all directions due to the having 2 motors in front and 2 in back. I feel like it would be very easy to control altitude. I am intrigued!
Kabab-Meister: Good work with the research you did on the subject. Your findings are consistent with what has become the golden rule in bicycle design, race car design, etc. Weight has an enormous effect on performance.
I recommend you consider rotational mass if you want to push this further. In our case it means the prop, nut and bell. Lighter components here will have a measurable effect on responsiveness and acceleration.
Rotational mass theory is:
Two quads with identical mass. The one with a heavier frame but lighter props and bells will outperform the one with heavy motors and a light frame.
You are the king of nescience...but somehow I still watch and enjoy your videos. Engineers aren’t guessing or making theories based on incomplete data or guesses. We use MatLab and model performance based on science.
Yep I explain that over and over in all my videos these days. None of this is science. It's purely conjecture based on observation and likely 99% false
Interesting stuff. I used to race cars and it's interesting to see some scientific-ish rationale in favour of how the 'light weight is faster' rule porting over to quads. My own observations do tend to back up what's being asserted here as well...but not entirely.
I think there's a big hole in this theory which is raw power + track type. Using cars as an example, the one (often only) place where a light weight car isn't as fast is on a long straight. On a track with enough long straights a heavier, more powerful car with a worse power to weigh ratio can claw back huge amounts of time against, and often turn quicker laps than, a lighter car which can accelerate, brake and turn better.
What I'm getting at is that 'disc loading' theory may well be a very valid working model on tight tracks with lots of turns (think sub football field size) but I suspect that on larger, higher speed tracks (think football field size or larger) a more powerful quad would tend to dominate even if it's heavier, as long as there's enough of a power advantage.
I think track size + power would be an interesting theory to test out given the huge variety of FPV racing tracks we see out there. The MultiGP Nationals track, Ibiza Euro Cup track, UK Nationals track and the Drone Worlds track in Hawaii were pretty huge, which is quite a different ballgame than stuff like the MultiGP UTT tracks or a lot of 'weekend' tracks that I see people flying typically.
On lots of the shorter tracks I don't think many folks even hit (never mind sustain) full throttle very much, if at all, and I've almost never seen a big enough space where quads are able to fully wind up to, reach or sustain top speed.
Personal observation from quad racing - disc loading theory would seem to suggest that I had better get my Lumenier Skitzo motors out again (super light!) even though in practice I've been blasted pretty badly by guys with more powerful quads while running those motors, even on tighter tracks. Could of course be piloting and not physics. Counterpoint to my own argument then - the really fast guy in my area (think top 20 or 30 in Europe) has recently swapped from his high kv setup back to old Cobra 2204 2300kv motors and started practicing with the intention of staying literally as close to 100% throttle as much of the time as possible. In that 'kamikaze; mode he's still usually quicker than I am but still measurably slower than he is on his ever so slightly slightly heavier 'monster' setup.
Point being - I basically think track layout is a huge unexplored variable and I'm not convinced that we as pilots (in general) are consistently using enough of the full potential of our machines yet (think percentage of maximum available throttle and time spent there, maximum available cornering 'grip' and speed, etc.) to be able to say with much certainty how much speed is in the pilot and how much is in the machine.
The track layout and your car references do make sense however cars don't fly. You don't really have the ability to hit the breaks as you're flying and you can only drift so hard into a turn even if you forget about the next turn ahead. Tracks that are just straight shots back and fourth are dumb and pointless. Might as well just do vertical drag racing. I'd argue that yes, something heavier can overpower something lighter but that mainly comes down to component quality and power per gram of weight. For flying, you can't get away from weight. With cars, a lot of the time weight will help in the form of improved grip. Staying near 100% throttle also probably isn't gonna do it but moving towards lighter motors and generally lighter setups can. For a technical track, no doubt lighter will be far easier to fly. On a wide open track, you can fly anything but the lighter one will still probably win because it can get up and go faster.
This is all still in its infancy. Lots more to come as we all improve.
This is just the basic law of inertia. You don't see semi's out-performing Ferraris on the track, nor do you see cargo planes maneuvering like F18s. Something light will always be quicker and more agile than something heavy. Applying more torque/HP on top of more weight only increases low-speed pulling power.
On the same token, overall high speed can be increased with a little more weight. Adding weight can put inertia on your side as drag is inflicted upon your craft, but when we introduce drag to the equation, you also have to introduce aerodynamics and efficiency.
It's all very complex, especially when we apply our thoughts to flying crafts. I think Kabab did a good job keeping the theory simple without diving into all the other tangents that apply to the situation. It's exciting to watch as the industry gets closer and closer to the "perfect" equation, and as more building techniques and materials are researched!
I really like this reply a lot, but I think extracting the right relevant information from it frames this whole setup a bit differently. The amount of time spent at wide open throttle on a car is going to be a pretty considerable portion of a lap on a big open track, whereas with a human pilot on a course, we're talking single digit percentages. The analogous place where that happens in cars is parking lot autocross, and if you look there lightweight and traction rule the day provided good piloting and no untoward behaviors of the car.
Track layout matters a whole lot, but looking at where and how much full throttle happens, the time savings in a straightaway can be measured in tenths, while getting from the apex of a turn back to unloaded high speed adds up to seconds.
I see a use and a need for the stouter motors in that they allow for a wider variation of prop setup (that can work well and be controlled across a larger range of loading parameters), and those will feel incredibly fast because they're moving lots of air and don't start to trail off at the top end.
Then again, I'm quite new, and the guys I fly around out here can smoke most any mortal if flying a well-sorted turd, as such the courses tend to be pretty involved and precision oriented.
You display a lot of integrity by posting this video, and provide valuable information on top of that. Well done, I just subscribed.
Thank you
the42the42 I try but surprisingly this particular video has gotten a good deal of negativity. that's actually kinda interesting since it is an advanced topic.
After watching a number of your videos, I have to say that you do a great job of explaining complex subjects in a clear way. Keep up the good work, can't wait for your future videos. :)
the42the42 thanks. it really is difficult to explain this stuff in a way that I don't get a load of flack about it.
Well, that is how it is with relatively new, complex subjects, unfortunately. There will always be those who buck against anything that doesn't mesh with their personal thoughts and ideas. Stay honest, it suits you well. :)
My brain hurts but I’m sure I will watch this a few more times. Good info thanks!
Nice explanation man :) That's more than likely what I experienced when comparing ulx or any quads around 230-250 grams dry against 300+ regardless of track and it seemed to handle turn and do everything faster. Almost to the point of brushless with no momentum carrying through turns. Acceleration etc much better. Nice to hear theory behind that :) keep up great work
It's sure interesting to consider these sorts of theories, especially since different people have such differing ideas about how things work. For example, we have bulbufet talking about how little weight matters, how he prefers heavier motors because of their extra thrust, completely contrary to what you are trying to prove here.
Jay Anderson well I haven't seen that video, but I assure you that the very top pilots and racing quad engineers use this theory a lot. It pretty much defines how they build. heavy build is fine, but it has a lot of limitations. a purpose built quad is always the best performer.
Everything you say makes perfect sense to me - I have some new ideas for my next build that's for sure
Kabab, I love the fact that you analyse the physics of these quads. They're still new 'tech' so theres less hard and fast rules out there (unlike car racing), thats what makes this so interesting as a hobby. In response to a few of the hate comments- A small suggestion might be to label your theories in categories and sequence so anyone can simply check the latest 'theories' to save your rebuttals. Just a suggestion.
Anyway keep em coming- loving your work
Yeah these are all just fast and loose ways to assess your planned build or compare quads. People think I'm preaching or teaching facts sometimes.
Great video. What frame was each one using? What would your top picks for 5 inch motors be now? Cheers!
mikenxzz HyperLite Evo HD on the left, racekraft frame on the right. there is no top pick for 5" motors but some of my favorite ones are the HyperLite V2 2600kv
Interesting, Cheers!
Tom Smith FPV did you see that there mythical creature lad? He was bright and glowy up in the sky!!!!
haha I did indeed ;)
I came to the same conclusion some time ago. Two days ago I uploaded my latest designs on AP ,waiting for confirmation atm. One of this designs is a 4 inch 3mm that takes 1407 and 1807 motors, thats a 12mm mounting pattern.But this is not going to be super light at is it a freestyle form frame and should come at about 55 grams. After watching Brians video the other day with the insane 4 inch 1407 build I think I will do a simple stretched pod style in 3mm for 1407/1806 motors and 3d print an Aio camera mount. I calculate this to be a sub 180grams dry maybe even less with an fc that has a pdb.
Elefkara Brian's lightest 4" is 150g dry. it's one of his fastest and most durable quads.
Kabab FPV very light indeed.
Whenever it is ready, link to your AP please.
Jonathan Edradan sure, will do
I wish there was more math on this. So many factors. Just lowering integral in PID controller can make your quad faster but slippery on the edges.
Michael Steele yes there is a LOT more to it. I'm just giving people watching some ideas. you can extrapolate things yourself.
Kabab FPV Thanks for bringing this up. Battery class is the greatest differentiater for race classes. It's like cc's in dirtbiking. Then open class needed. Separate events Acro VS. racing. Not sure on weight but seems right. I have 5s 4 inch quad that weighs 424 and 5s 5 inch quad 477. They are too fast to hit gates but interesting how much they fly differently. The 4 inch slices through wind like butter. 5s should only race in open class in my opinion.
Michael Steele heh, there's no such thing as too fast. those weights are not that light either so they could go faster. 5S is the highest end of the voltage sweet spot right now.
Kabab FPV You can fly gates with 5S? Nice.
Top speed is MUCH more affected by DRAG than it is the weight of a craft. That's the whole reason a parachute works to slow down drag cars or the space shuttle for example. I was surprised you didn't even mention drag coefficient in your top speed portion...
Eganwp yes I did. you must have missed it. I explicitly state that top speed is another story.
You seem to be presenting somewhat contradictory points; if your goal was to reduce the disk loading number, it makes more sense to increase the diameter of the blade because that factor ( the radius) is squared, whereas reducing weight is a linear reduction of the disk loading number (depending on the weight and propeller sizes, I know for certain propeller sizes it makes more sense to decrease weight). For example, I have a quad copter running 10" propellers that weighs ~600 grams dry, and ~800 with battery, which would have a disk loading number of 2.54 which is less than half of the lowest value you presented, but obviously this quad could not compete. This theory may hold true within a set of bounds but presented as is, I do not think that it is valid. I do agree with your assertion that lighter is better in general due to reduced inertia. Lighter overall weight decreases linear inertia, and having lightweight motors, and centralized components will reduce the moment of inertia making the force that is applied result in higher angular acceleration. These two effects will result in better command responsiveness.
Sean Burke yes! you are correct! but as I keep saying to everyone, this estimation leaves out a TON of details. I also discuss how I give the heavier quad that's 5" a handicap over a lighter 3" even though the disk loaded number is less because it simply has more inertia to haul around. this is what you're sending with the bigger prop areas. also, note that all racing quads in the 1000 class will fly around like a super light. they'll just have more inertia...
Bob. We have never met before which is why I am surprised you would give me an early Christmas present like this. Or maybe it is a late Christmas present. Either way, thanks...Great video!
Catalyst Machineworks lol you bet. but if you read the comments up, you'll see that I've been getting more negativity from this video than any of my other ones. also many have messaged me on FB to tell me I'm full of it. the concept is over many people's heads. we can only lead a horse to water...
Don't worry about what people say. Physics is physics, regardless of opinions. Keep up the good work.
This is why 3 years ago I was designing 220g (without fpv gear) 5" quads.
and this is why my light 4" quad on 5s is such a beast! When I told them my 4" on 5s is faster than my 5" on 5s they all just don't believe me/ understand. it's nice to have some other more technical description of why this is.
Adam Komarek depends how you built the 4". it should be pretty light with a small 5S like 800ma. then it'll destroy any track.
Great theory. like the grams, it ALL adds up. Efficiency included. Still looking for the fastest, lightest, most nimble the end. Just fly.
good content & topic. thanks for effort, I know the time it takes to produce these & appreciate it.
My Fu-Rc Kore build has 2306-2700kv and is about 320g dry. I mostly built it for to speed and run 2 blades on it. This video is making me consider putting 2206-2300kv on it so I can go back to an avan-r. I'm so torn, thanks kabab...
The avan twin requires a really powerful motor. I wouldn't bother on less than a 2207 or 2208. I know it was made for 2306 but I haven't had good results (at all) with it on a motor of that size. I would recommend APC props for speed runs.
Kabab FPV 100% agreed the avan twin sags my battery hard and has no grip. The gemfan 5152 twin on the other hand was a revelation. Thanks for the reply.
Weight is also much more of a factor on a track with a lot of turns. If it's a massive circle or an oval, weight plays almost zero effect and a more powerful but heavy setup will win every time. The more wide open, larger and less turns a track has the less that weight matters and the more that drag, prop terminal velocity (peak rpm) matter. A light quad crappy powered will suck on a huge wide open oval track! None of this is new, it's is applied to many other power sports we have been watching for years. :)
Eganwp I would argue that this is not true. the light quad will likely keep up the same and will be able to do more laps due to its better efficiency. even in an oval track, weight matters. your mass is being flung out of the circle. you gotta pull it back with something. it doesn't just stay in line. top speed, as I said, is another story.
Kabab FPV I disagree. If that were true then the Reno air races would be won by the lightest smallest engine planes (to save weight), and it's not. Its always the most powerful plane with best consistency and piloting skills. Same with NASCAR. If lightest always would win the oval, why wouldn't the pace-car win the race assuming its lighter? Lol. Yes lighter is always faster, but you can't just assuming lighter and lighter always beats more power. If that were true then a bee flying should beat nascars around the track...
Eganwp well of course it's the pilot that wins the race. multiple setups can do the same thing too. I would simply just choose the lighter one in most cases.
In my experience, geometry and air resistance is king, then props, then weight, then power.
I have built over 9 different frames and the ones that are my favorite have one thing in common, they sound quiet in the air. One of my faves was an aimdroix blackbird, a heavy skinny arm quad with bi-level motor mounting and stretched H platform. The air going past the props was clean and although heavy, it was fast, stable and smooth, I took its guts out and built a Shendrones 5" X, it was 80gr. Lighter, but it flew like crap due to the short wheelbase, I could never get that locked in feel.
Yes more weight means more momentum, but the FC doesn't care, if anything heavy builds are easier to tune.
I'm not recommending pigs, but I know first hand light isn't always better and heavy isn't always faster- but clean geometry is always a must for good performance.
Im currently flying stretched cross frames and never looking back to X.
Also, you show a very tight track, obviously a lighter, smaller quad will win, but on a big open track, the larger quad will dominate just like a Miata Vs. A Viper.
Cross feels unstable to me but more power to you.
Have you flown a stretched + with recent firmware?
They lean more into turns and carry more speed with them as well, current betaflight firmware runs very well on these frames.
They feel weird, yes, almost like a flying wing that can turn on a dime, but, stability wise, for me at least, I get zero prop wash and artificial feeling flips and rolls, it will also carry speed and bank like a sport bike and slice up the air.
It's an interesting Theory but I find it to be wanting in detail. My first thought is that two propellers of the same disc size can easily give different thrusts and have different weights. So that when you put them on the same motor one prop will have higher maximum thrust but will create more drag and therefore not allow the motor to spin it up to speed as quickly or with the same amps. In addition a blade that has one blade versus a blade that has three or four or five each blade is creating more drag but not proportionately more drag. Take a 2 blade prop versus a 3 blade prop with the exact same blade Dimensions including pitch and line and area. The 3 blade will not produce 50% more drag than the two blade prop. but likely will generate close to 50% more thrust. Something to do with the propwash from each blade being closer together as it passes through the air.
It seems to me that the simplest way to calculate which quad will perform the best would be power-to-weight.
The Theory doesn't even take into account the number or dimensions of the blade of each propeller. However that would be irrelevant when all you have to do is calculate the thrust that one motor and propeller combination can generate with a given voltage. Compare that to the weight of the quadcopter and you should be able to calculate your acceleration rate. And as a quadcopter turning in a corner is equivalent to its thrust to weight ratio capabilities meaning when it goes through a corner in order to turn tighter it will have to slow down more there is a minimum turn radius at maximum speed for any given quadcopter to reduce this turn radius at a given speed you must increase the thrust or decrease the weight
Hey I just wanted to let everyone know that this theory has been drastically simplified and you should extrapolate the idea yourself
Hi Bob thanks for the interesting video...I might try a superlight build...how much does the hyperlite evo 3mm arm weigh? I couldnt see that detail on the pyroflip site...
Thanks for update!
With battery voltage being a determining factor for class, I feel like for a viable 6S quad you need to reduce the motor KV to the point that you may as well just use 4S and high KV motors. The only advantage I see with 6S is lower KV motors, which means less current, so smaller wires and ESCs, so you could save a little weight.
Adam Wilkinson 6S is a bit much weight. also, on a light setup, 6S is no big deal for the motors. Ricky runs 5S and 6S on the light quad and it doesn't even get warm. he only uses XM20 ESCs. 5S is far better than 6S however. has the power without that much added weight.
I'd assume you'd want to keep the weight about the same, so 1.3Ah*14.8V=19.24Wh
19.24Wh/22.2V=0.866Ah, so you'd be looking for maybe an 850mAh 6S to keep it similar. But my point really is that you can have a similar performing quad at different voltages. So, 2300KV*14.8V=34040RPM, 34040RPM/22.2V=1533KV, so if you have a 1500KV motor and a 850mAh 6S battery, then it's the same as a 2300KV motor with a 4S battery right? And by that logic, if people are running 6S on 2300KV motors, then why not just use 3450KV motors on 4S?
Adam Wilkinson while this makes sense, you're missing one very important aspect. the torque added of higher voltage. you simply get loads more torque. this torque improves all aspects of flight. past 5S is no help however. you're getting too heavy then. a superlight 5" on 800ma 5S is too performance right now on planet earth. like an 850ma 5S on 5.5" would be better but those components don't exist yet.
Thank you for this video! very informative. I wanted to argue everyone's point on a heavy quad going faster so bad. physics just doesn't work that way. inertia and wind resistance are our worst enemies!
Am I the only one having trouble following this? I mean, with all the corrections in the description, the overlayed text correcting what's being said, the admissions that he was completely wrong in the last video theory, and the constant reminder of "over simplification" is there a reason anyone should take what he says seriously? Just seems like a bunch of confused nonsense.
Verbal Tease I'm sorry it may be a bit confusing. I present information when I feel like I've matured my knowledge of it. the last video of heavier quads was a joke and just a rebuttal to Stu and Josh. I also didn't properly think through what I was saying so it wasn't fully correct. this video however is. I will try to be more cohesive in the future.
Kabab FPV If your goal is to present a theory based on science, present it methodically, as science is supposed to be presented. If you want to state opinions based on subjective experience, that's totally different. The first way doesn't require any trust or confidence because you're giving facts. The second is normal blogging; entertainment without much substance.
I have an interest in quads and the theory behind how they work. Watching you ramble on for 16 minutes was disappointing because I thought it could have been stated much better in a fraction of the time. I appreciate the sharing of information, just wish it was structured better. Thanks for reading my feedback.
Kabab FPV If your goal is to present a theory based on science, present it methodically, as science is supposed to be presented. If you want to state opinions based on subjective experience, that's totally different. The first way doesn't require any trust or confidence because you're giving facts. The second is normal blogging; entertainment without much substance.
I have an interest in quads and the theory behind how they work. Watching you ramble on for 16 minutes was disappointing because I thought it could have been stated much better in a fraction of the time. I appreciate the sharing of information, just wish it was structured better. Thanks for reading my feedback.
Verbal Tease I agree with your general assessment of this video. using the method of writing notes to cover made it more cumbersome than it could have been. I won't do that again. I'm still just learning. I also have a real job and just do this for fun because I enjoy teaching what I've learned and discussing. there is little science being presented here as you can tell. nothing follows any scientific method other than observation. I'm still just getting used to making videos. I'll try to improve in the future. these videos presenting complex ideas are far more difficult to make.
Great info! Appreciate your time and energy in putting this stuff together..QUESTION- I saw Brian's 4" with 1407 motors, what 4" frame has motor holes for 1407's?? He cuts his own frames so easy for him..I haven't found a
4" that you can mount 1407's on.
There are only about two on the market and I'll be making one as well however as I present in this video, a super light 5" is gonna perform better so I'm focusing on that.
Kabab FPV Cool! Get yours done! I'll take one ASAP.
I've been playing with many designs but I just can't get them to the weight I want. It's most likely gonna be just an elongated 3" to fit the 4" props.
Kabab FPV Even better..keep me/us posted.
Very interesting! I might mess around with that math equation myself and see what I can come up with. There also seems to be a dearth of 2204 motors on the market. Though that shouldn't be all that surprising I suppose. After parsing through MQTB for oh, 5-10 minutes, the lightest motor I could find was the RCX SE2205 (A bit surprising honestly) at 25g. Though all my motor info comes from MQTB, so I'm sure I'm missing something. With that tangent out of the way, great video as always! I'll be sure to pay closer attention to this stuff in the future.
I'm still rocking rotorgeeks 2204 2300kv motors. I wish they would bring out a more up to date more powerful 2204 motor
STRYKA FPV I think we will start seeing more powerful 2204's that are about 22g some time soon.
+Kabab FPV really hope so cause I really love the rotorgeeks ones
sunnysky 2204 - my favourite motors since one year.
Simon Sais yep they're still reasonably good motors.
Thanks for the video, very interesting to have new variables and theories to consider. I know there are no absolutes, but what do you suggest as a target weight for a 5 inch 2600kv copter, mostly used for acro?
I had been going for 1500mah batteries, but maybe I'll have to switch to 1300's on my next purchases.
for 2600kv, I'd recommend a dry weight of no more than 265g. You could use 1300 packs with it too.
Kabab FPV you might be interested to know I was thinking along this theory as I was asking about the 2520kv , my alien with HD cam is like 680 grams , I'm a race car guy and that weight turns my stomach, my new build with camera battery everything will be just under 500 grams,that makes me happy😁 good video
Finally someone said it :D Great video man!!!!
Hello!
Great video and Channel.
I was wondering, what was the setup on the superlight quad in the beginning of the video?
I wanted to test to build a superlight quad and im struggling to get down below 250 at the moment.
Thanks!
alibobba1 racekraft frame. Pyrodrone 2204 2550kv, xm20, some FC and whatever FPV stuff.
Your Videos Are awesome But One Thing everybody seems to blend out is drag and surface area. I calculated that a quad with 50% Less drag could reach about 30% more top speed with The same thrust factor. This came to my mind after i maidened my iFlight ix5 and felt it was going way faster than my other quad with same Motors But more surface area
Tourensohn MotoVlog sure but on an ultra light, the arms are already only like 6-8mm wide and the body is as small as physically possible. how else would you like to reduce drag? particularly without adding weight. I'm not concerned with heavy acro setups. that's a whole different thing. also, this little ultralight already does 90mph on 4S. how much faster you think you could go on a track ? they're usually not just wide open straight shot.
I think you should see if you could build the "lightest quad ever" kind of scenerio even of strengths sacrificed
My entire life feels balanced again, thank you. ( I fckn knew there was something wrong with that!)
MikeDrones lol you're welcome.
I like your Theory... Well thought out.
depending on target. i never use more than 2blade props and frames above 60gr. motors fat handwinded like efaws.
Yep. You're right. Great overview! :)
What were the two quads being compared.? Were they both POD style as in Hyperlite or Srike? Never seen a full body quad with a dry weight of 225
SSBelmont left one is the HyperLite HD, right one is the racekraft frame.
having the sun in shot right next to you is hurting my eyes.
but im loving the science.
John Doe lol sorry I'll take that into consideration next time. I usually only have sunrise to shoot anything.
At the end of the day, it all depends on the pilot and what s/he feels comfortable flying with.
Thanks for the insights man
Are races regulated nowadays such as weight, prop, motor, battery and frame size or is it still bring what have and you can enter the race? Do you think this hobby will be regulated like all the other rc genres or is it still too new of a sport?
jeremy.n79 not yet but I expect that to start sometime soon.
Great video Kabab, I just thought that you would be interested in a post just made by QuadMcFly via RcGroups where he states that there is a lot more than you're explaining, and that what you are explaining is only a piece of the entire puzzle as a whole, just wanted to know what you make of it: www.rcgroups.com/forums/showpost.php?p=36926229&postcount=3268
I talk to Ryan about a lotta things often. He's one of the very best sources of information. That is a fantastic post that I didn't even know he wrote. I've been trying to convey all that in some videos but it starts getting too long with examples or too confusing. Text is really better for this kind of dense information and he did an amazing job.
Kabab FPV Hey no worries brother, he just posted that reply tonight after I shared your video in the motor performance thread on RcGroups, and wanted to know his thoughts on the matter since we have been discussing the subject further, to include fluid dynamics and physics of the models we fly. Keep up the great work man, you're doing and explaining more about the technical aspects of this hobby than 95% of the people I know and follow, which is commendable 👍
I'm very happy to be stimulating discussion and thought but I can hardly begin to live up to the work Ryan has put into it. If I was to name anyone the most knowledgeable about this sport it would without a doubt be Ryan. Then maybe Brian Morris.
Good thoughtful POV. I always knew lighter quad is faster ;) sorry Stewart, Joshua...
Watched the whole video and you present some very interesting theories. Not to take away from any of that - but there's something very wrong with the left hand quad in the head to head at the beginning if that's as fast as it'll go. Me and most of the guys I fly with have 5" setups of similar weight to that and that thing looks like it's being flown at half throttle.
Yes it is the fast it will go. Ricky is a crazy fast pilot. You really need to be a world class racer to beat him. This track requires a lot of direction changes. Anything with a little weight is gonna suck at that.
Kabab FPV I fly with a bunch of people who competed in the Hawaii world's and they all fly setups closer to the left hand setup than the right hand setup. Their quads all go much faster than the left hand quad, even on a track such as this. That right hand quad is fast, I'll give you that, but I don't think the left hand quad is a good representation of top end performance you can achieve with a quad of that weight.
I was just told by the track organizer that before Ricky's light quad, the track record was set by a 324g dry weight quad and it was 26 seconds. We in CA are definitely not slow pilots. Ricky is literally one of the fastest in the world as are a couple others down here. The light quad did it in 20.8 seconds and that time was far more consistent than the heavy one. He can also do two additional laps than the heavy quad on a battery that's 30% smaller.
Kabab FPV definitely not arguing that heavier is better, just that that particular heavier quad seemed slower than others of similar weight/setup. But hey, you're the one with DVR and lap times, I'm just saying 'it seems slow', haha. In any case, I appreciate the discussion and your interesting videos. Cheers!
I agree. When I first saw it I exclaimed that he was just cruising too. He wasn't however. The thing just can't carry its weight through the track that quickly. Can't get on the power and make it around the next turn.
Seems really random, hope an engineer explain
There is a sweet point.
Too heavy = bad
Too light = bad
Find the happy medium with your quad
The heavier one is better for a less experienced person and the lighter one is better for a "pro" because going around corners with a light quad will be harder.
ClevelakeFPV na I think lighter is always better. especially for the beginner. it won't break so easy.
What about a theoretical 150g 5" quad in turbulent air? Generally lighter is better though, but at some point we are just measurabating instead of flying.
Are these "notes" from lumenier company ? :D I guess so. So here we are. If you are right, why so many pilots using lumenier lightweight motors (whitch are basicaly only 22g +- 5inch motors on market) arent on first places all the time ?
Jan Prejzek I'm sure they're using these calculations. it's why the skitzo motors seem so crappy. they just didn't tell us how to use them. they're actually excellent race motors if built right. they're just way too expensive to use for anything. I believe this is also why skitzo was testing 1806 motors a while ago. those motors never came out however because he public doesn't properly understand concepts like this.
I'm optimizing frames since a year, because i was not rich enough for all those new hyperlite motors and so i kept my 2204 :)
a shame i sold yesterday my sunnyksy 2204 2300kv (21g) for sunnysky r2205 2500kv (33g) - two things i noticed was the extra weight of 40g - the difference is most noticeable where the drone have to change the direction abrupt. secondly my 1300mah lipos have too little capacity to live more than 2 month with those monsters.
the R2205 are faster at the top end no question. but if you have to change your direction 40 times (which is normal for a race) it would take longer each turn to recover the extra weight.
but a 2205 has the power to compensate my action cam, which a 2204 does not have. thats why i am not soo sad about it. however:
i was not really interested to this moment to design a frame for 1806 or 1406 motors, but now i will. there it not much to save weight except - motors x4, battery, esc x4, frame (in that order) - the rest is secondary.
i designed my first frame with hole in the 3mm arms, to proove that RCmodelreviews was wrong. however - i sell them since a year and nobody was able to break them.
keep your direction. you do way more professional than others.
Simon Sais the old SS 2204 is only 21g?! I gotta get me some of those.
yeah. they were my first and most durable motors i had since i started fpv (feb016)
No need to complicate things. Physics is simple. Second newton's law "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. (F=m*a)" It all comes down to the race track. You need really high max speeds or you need a snappy quad? In a tight race there is no point to have a quad that can reach up to 150km/h but needs time to do it. It's better to have a snappy one that reaches 100km/h or even 80km/h instantly.
Hey Bob, how do you account for 2 or 3 blades? Is it relevant?
There is probably a sweet spot. Too low disk loading, and performance may go down. Haven't given it too much thought, but with skydiving ram air canopies, wing loading is taken into account and people shoot to aim at a certain sweet spot to get the best performance from their parachute (wing).
Matt Brozyna well yeah that's a totally different story. there isn't really a too low for spinning blades. for a parachute you need to have a counter balance for the parachute to stay open.
Last time this theory, now this theory, what's next?
Sorry but thats just talking while riding the hype train..
Real physics is way more then this.
YannikW Well, he's actually repeating all over the video that what he's saying is super simplified
DanutsFPV I can't seem to say it enough or people just skip through it. I'm actually getting a good deal of negativity to this video. more than my other ones. people think it's hype....can only lead a horse to water. I guess there won't be a wave of people moving to super light super fast quads. that's fine, easier for the ones that understand to win.
very interesting thanks for the info ive done a 4inch build weighing in at about 255grams but the motors are the new rs2205s 2600kv red bottoms, what would be a good motor if i was to go to a smaller motor? im uk based so nothing that is in the states lol
The Brother Hobby T1 1407 3600kv on the gemfan 4x45 twin blade prop and a sub 40g frame.
got the rfx160 so its perfect just ordered these and will switch out the motors and see what happens with bullnose tri blades? (4inch) thanks for the advice too
so...heavy powerful good?or light good?
So is Ricky's light quad running the 2304 motors using 4 inch or 5 inch props?
Mike Aarset 2204 and the RK5038
Kabab FPV thanks! Which makes sense. Same disk area 😜
So would a quad that can run 6" props and is also light (330g dry) run better on 6" props than it would on 5" props for racing? Just wondering in terms of speed and cornering, flying 6" feels a lot more floaty to me.
Eagle151551 yeah 6" would have more control and a higher cruising speed. you just need to fly at more angle on light disk loaded quads.
Thanks for the info
15inch quad would need to spin props at 25k for 70mph i don't think so mate.
Not unless your running a 15inch prop with a stupidly low pitch.
Remember that the tips on the bigger blades have a much higher linear velocity which would generate a higher thrust speed for the same rpm on a smaller blade with similar blade angle.
Stephen Gibb yeah I consider that but still have a hard time believing something with 15" blades can achieve 80+mph with relative ease.
Heavy quads fall faster and are faster while flying upside down
emile lol yeah that might be true.
This is all very relevant info, however....dare I say 95% or better, of this sport is skill. I wish there was as much time spent on flying techniques and strategies. I would like to see this much attention spent on finding the best lines to fly on a course. start strategies. gate aiming. and everything else that is relevant to improving . I do get a lot out of these quad theories, and the nuts and bolts videos. but I would like to challenge the video gurus to make more flying Technique vids.
This is the same pilot that's as good as any pilot right now which is SIGNIFICANTLY faster on the lighter quad and more consistent too. That says a lot. It's one of those things that more and more people will realize as they improve. That being said, I can talk about racing line all day but what's the point if you can't execute? Flying technique is mainly just practice. You learn to carry your speed through turns by doing little dive maneuvers naturally. Here's Shaun Taylors strategy. Get out the start extremely fast. Stay in first the entire time. If someone passes him, he gets all messed up. Good for him that he's really frikin hard to pass. Here's another strategy, let everyone else go first and expect them all to crash...
Based on this theory my tiny whoop would be better than my 5".
TransAm2k4 with a disk load number of about 5, it's definitely more agile than a heavy 5". can't dispute that. but as I keep saying in the video, this concept is hugely simplified.
So disk loading is almost equal to wing loading, in a way?
Aaron Gerhart I feel stupid for not thinking of that but yeah that makes sense.
So you're saying to run 1806 motors with 5 inch since its lighter? This theory has quite a few flaws in it. There is no linear relationship between performance and weight, it's definitely waaaay more complex than that. What would be far more valuable would be to plot the thrust to weight ratio across the entire throttle range as well as the Grams per watt that is being output. What determines how well a quad performs is its throttle response not its peak thrust to weight otherwise everyone would run high kv with bi blades. But the lightest quad for a given prop size does not give guaranteed increase in performance or a 5 inch with 1806 or even 1407 motors would outperform a 22xx motor with 5 inch props simply because it weighs less by your theory which really doesn't make much sense.
MewoFPV this is an entirely different discussion. I'm just presenting a way to quantify performance across weight classes. of course you can't run 1407 motors with 5". but as I said, that's a totally different discussion. this calculation is what the top pilots in the world use to decide what to build...it's an advanced tool.
Kabab FPV not any top pilots I know.... Nytfury runs 2306 motors last time I checked. As well as 1500 mah graphenes so not very light.
And to go further to say that weight is the only deciding factor would be to imply that choosing a motor that weighs 1 gram less than another and outputs 700grams less peak thrust would be a faster quad because thrust doesn't matter...
MewoFPV First off, I keep saying in the video that it's super simplified here. next, Shaun Taylor runs the Hyperlite 2206 2700kv on gf5045 twin blades for racing. he does not build super light stuff because his crashes are pretty tough and even he doesn't like fixing everything all the time. for actual racing, he probably flies his lighter setups. also, I'm saying that yes, on a technical track, the 1806 5" would perform better. on a wide open tracks, a 2204 5" would perform better. on an extrmely wide open track, a light as possible 2206 2700kv could probably keep up with the 2204 equally. there's also the GoPro to take into consideration. if you're planning on carrying one, you absolutely need the thrust so must build heavy. this theory that I represent is extremely simplified. as I keep saying in the video. take the idea and use it. it's not an absolute and I haven't quantified even 2% of the real world into math here. also, if you think the theory is incorrect, I would actually love to see a video where you build an 1806 5" that's 190g dry and race it against a 450g super power build yourself. I think you'd be quite surprised with your findings.
Yea I just thought the example you used was pretty misleading. You compared Ricky flying a 335g dry quad vs a 224g dry quad and emphasized his use of old lighter motors made the quad faster. The motors don't account for more than a 20-25g difference so he's flying a totally heavier quad. I'm afraid your data will mislead people to take something like hyperlite v4s off of their quad and replace them with like Cobra 2204(5)s to lose 20g and wonder why their quad is way slower. Even considering it's oversimplified, any application of your claim would not be consistent with the effect you'd imply. I have light warpquads that have old 2204s on them and they're slower in every way than my 300g quad with 2206s.
pretty interesting stuff.......i have a set of the piroflip motors 2204 - 3050 kv and it screams on the dal 4045v2 props...i run 1000mah lipos ...its a touch heavy ...285g without lipo.
What kind of performance would low kv motors on a light quad make?
Similar. The kV isn't really that important but on a lighter quad, it actually can move quicker and take advantage of the higher kV. Still the effect isn't enormous and your balancing how many amps the battery can supply. I'd say you really don't need anything beyond 2500kv on any setup. For 5", less than 2100kv can be slower however.
Also, shouldn't the angle of the prop blade be put in the equation. It feels like that would be another big factor in the performance of your quad.
There's a LOT that's missing from the equation. The way the pitch works is that the heavier quad actually needs less pitch since it can't make use of the steep pitch. This is likely why all the top acro pilots seem to prefer the flatter 4 pitch too although the butter cutter prop is doing well. I'm not sure it's actually a 5 pitch however. The lighter quads will work way better with a steep pitch. This is likely why matty stunts likes his super aggressive DAL 5x4.5x3 HBN props (which are really some of the worst props ever made for a number of reasons).
What frame was ricky using on his light quad?
Bram Otten that was the racekraft frame which is 44g
for this theory, using a real world scenario is not good data, there are just two many variables.
however logically it should show truth.
So you talk a lot with Brian... he might have mentioned RaceFlightOne (RF1) and tried to convince you? :-P
JulianGoesPro he's told me how he won't fly anything else. I'm not against RF but I haven't been particularly for them in the past. if I received some test equipment I wouldn't turn it down but I have no reason to try something else right now. Betaflight is working really well for me. in the past, RF has tried to kill me a few times with random quad reactions. also cost me a number of burnt motors. I've been scarred...
thanks for the reply ;) Let me see what I can do :-P
Awesome job once again my friend :)
You deserve million of kisses for your hard job!
Have a great friday
Somebody needs to tell Minchan this then , allthough he seems to be hard to beat even running 2207's and 1550mah ;)
Mad respect.
can u make video on aerodynamics, how much faster is like MIFUNE drone over a QAV250.... thx
Gino Poe I've wanted to but I think I'll actually piss off a whole lotta people with it. the mifune is not actually faster. in fact it's most likely slower. I'm pretty sure one of the most aerodynamic frames is the helix. I guess I'll attempt one and try to make it not so harsh on the topic.
you have covered the issue of weight, now how crucial is aerodynamics?
This is what Mclaren have to say (regarding bicycles) "The McLaren software also makes it possible to adjust any parameter to see how a change affects performance. My 56cm ViAS weighed 16.9 pounds, which is heavy relative to climbing bikes. So I asked the engineers how much gain one would make by cutting a few pounds. A quick calculation revealed that cutting the weight by 1.9 pounds (bringing the bike to the UCI limit) improved the 11.9-mile time by 3.2 seconds-that’s paltry relative to the 120 seconds gained through aerodynamics."
Gino Poe yeah aero is important but it's not how you would imagine for things that fly and are primarily just props. I'll put together some graphics and thoughts to present. thanks for reminding me about it. I personally believe weight is more crucial than aero.
go harsh, for more dramatic effect and response.
Its funny, we fly these "aircraft" but i havent seen a video on aerodynamic comparisons with drag co-efficience and lap times etc... yet the current design of quads is dragging a single flat plate across the air, i guess its acceptable in 2017.
the only quad i have seen is the DEBRE which focuses on reducing front profile but i dont think its going to production. I would be good to see more focus and radically aerodynamic designs come out to compare its benefits.
It does have an impact but I don't think it's huge and the main issue is that adding weight to improve aerodynamics takes away from control and agility. We also don't have air brakes so I feel like the drag isn't a horrible thing. Especially on superlight setups.
that's a connex HD quad vs good ol' analog
what about the HD cam like a gopro?
? what about it? If you want to race with a gopro, I'd recommend a 6" build. The issue with 6" is that the props are not durable at all. So you're stuck with 5" and poor performance due to excessive disk loading.
thanks for the reply.....i think the conclusion is high spec with more weight is not guarantee win the race than low spec but superduperrrrrrr light...
Right and if I was racing on a budget, I'd use garbage components and just build super light.
It's heavy, a lighter one would be better, but not necessarily give better video.
so basically a lighter quad is faster
Joe Wade it's not quite that simple but yes, you should generally try to keep it light.
what do you consider dry weight?
Means no battery.
THANKS!
dude your theory could even be true but the DVR of both quad cant be compared. The quad on the sx commits error while the other one is smoother on the cornering. 7sec on a 30sec circuit is not normal.
what were the two frames?
perfectprint HyperLite Evo HD and the racekraft frame.
no wonder i am just faster on my hexs around my track than my quads.
Neil Fraser yeah. far lower prop loading
1804 motors only weigh 13g and 1308 motors only weigh 14g.
Right the 1804 would be good on 4" but the 1308 would be a bit over driven I think. The recent 1407's are really well built and super powerful for their size however.
Kabab FPV I've changed my opinion. The tmotor air 2205 motors weigh 21g with short wires and are lumenier smooth. You just have to epoxy them to the frame so they don't rip off mid flight and you're good to go or fly with 4 screws. I'm not buying anything else for a while now though, I'm going to just fly 6s because its amazing.
LOL, 6S FTW. Ryan says that past 5S is diminishing returns with our setups these days.
Kabab FPV I think if the escs accepted it and more people had higher cell chargers, people could fly 7s or 8s like no joke. I can't tell a heat difference between 4s and 6s, maybe the battery. I ended up making some lowrider zmr with the battery perfectly level to the props and it actually flies better than my 185 terrible shakey x banggood frame. I couldn't believe it. You probably reply to comments all day because you got like 3k subscribers in the past month. And I see how if your changing the hobby this much.
Take an imaginary motor of a 0101 and let it = 1.0. Torque increases at r^2 and linearly with height. Radius calc is 18-01 = 17. 17/2 = 8.5mm which is the difference in radius so 8.5^2=72.25. The stator is 4x taller so height difference is 4/1=4, so multiply these two together to compare torque to the theoretical 0101 motor. 72.25*4 = 289. Doing the same for a 1308 = 36 due to radius and 8 due to stator height which total 36*8=288. 289/288 is = ~1 so and 1804 and a1308 motor should produce about the same torque for a given power. A 1407 = 6.5^2*7=296. 296/289 = 1.02. A 1407 motor should have around 2% more torque than a 1308 or an 1804. You can calculate power density from this to figure out what motor gives you the most torque per gram :) This isn't exact, but it gets you in the ball park.
atleast somebody took a step back and said hey wait a minute more weight=more speed waaaait WHAT?....
DeeRodLive except that if you read the comments, I'm getting a surprising amount of negativity for it...can only lead a horse to water...
Speed is basically dictated by aerodynamics, rpm and pitch... weight doesn't really matter. Speed is not acceleration. Weight has a big affect on acceleration but very quickly air resistance dominates everything and weight no longer really matters. A 1kg and a 10kg object of the same shape/size have the same air resistance. Presumably the heavier object will have more power though push through air, making it faster.
+Kabab FPV I went for an ultralight build using your hyperlite frame and came out at 238g dry and 350g AUW with a 900mAh lipo rotorbuilds.com/build/2873
Thanks for the idea ;) (edit 4g mistake on the weight)
Wow that is definitely the lowest weight I've ever seen. And I just saw 250 a few days ago and thought that was amazing. How does it perform? That thing will definitely never break the frame. The frame is far too much for that kind of setup. I should be receiving my new sueprlight prototypes some time at the end of this week. Would knock another 30g off your setup. Definitely sharing this on the Hyperlite FB page. Really nice write up.
How much do those motors weigh? I thought they were like 21g or something. I remember looking them up to be the absolute lightest 2205 motor...
Thanks for the kind words. To answer your other reply the motors are 25g with the longish wires they come with, and I still had to lengthen them to reach the center stack. Frame came out at 69g with the hardware needed to mount the fc. I haven't had a chance to fly it FPV yet, but test hovers in the backyards tell me that thing will be suuuuuper reactive!
Can't wait to try those ugly brown hyperlite motors when they are in stock haha
Yess i always stongly believed lighter is better 😎😎 and now there are numbers 😁😁 (its funny becouse the people i fly with are always wondering why i can almost fly a minuute or more longer on a 1300 then they can, and then i say: well i am 150 to 200 grams lighter. (This was already happening last summer)) so this video makes me very happy 😁
isn't this kinda common sense.
You'd think so wouldn't you. Scroll down and see how much hate bullshit comments there are...
Based on your video i started to make downgrade my race setup to 21g motors: facebook.com/skullndrones/ - check out the latest video.
The agility boost is insane. Even with 1300mAh Lipo. (Tattu 75C reduced to 142g) - the AUW: 400g
With this setup i made a 1/4mile race against a hyperlite 2206 on a stretch setup (AUW 450g) - with the same times. Around a tight course he had no chance.
Next step - carbon frame, 4in1 esc and micro camera. Thanks for your inspiration!
Simon Sais some have now built sub 300g 5"setups now and are re learning to fly it's so fast
Btw there is some non existing motor with 25g weight (between 22 and 28) ,-) if someone interested.
rotorgeeks.com/index.php?route=product/product&product_id=396
Sorry Kabab
The Hyperlite/ZMX V2 2205 motor is the same weight and much higher construction quality in terms of power output so those motors were obsolete before I even knew about them. I also have my own 21g 2204 prototype motors on their way to me in a week or two with much more modern and higher build quality.
Very early on Rotorgeeks screwed me for no reason. Sent me some faulty ESC's that ended up destroying themselves and the motors with them. They blamed it on me and said I didn't bench test the components enough before flying (which is a ridiculous thing to do. Nobody spends a day bench testing before flying). David Klein, the owner, reluctantly half apologized to me over a year later but it was quite possibly the most negative customer service experience I've ever had since they were basically telling me I'm absolutely wrong in multiple emails and I didn't provoke such a response. I still have the emails and David is now aware of me. David cannot even give a customer an honest 'sorry for bad support.' Rotorgeeks is not a shop I would recommend to anyone despite good experiences others have had.
Yea, it is littlebit about time when mentioned motors come on market ,-). I saw these Hyperlites V2 too yesterday. Obviously sold out as many other motors on that webpage :))
How about those Air 200 2205 - 2650kv? www.miniquadtestbench.com/t-motor-air-200-2205-2450kv.html
At 23g (21g) on short wires they could be a winner coupled with HQ 5X4X3 V1S (3.5g). Amp draw should even be low enough to use a KISS AIO CC that caps out at 21A.
Now if only your hyperlite EVO frame was in stock... :D
Nice video!
I pretty much won't run any motor more than 24g anymore on anything I intend to race. Acro is whatever. Totally different story. As long as I have the power to pull out of a dive easily it's fine.
frame should be back in stock tomorrow really. It's been too long since China returned already.
Very true acro is really what feels good and smooth and can carry the gopro with ease :)
Great news for the frame!!
So basically low weight+ large prop size= $$Profit$$
Hans why does it equal profit?
Oh sorry; the term profit has taken on a different meaning in internet culture these days. Profit in the terms I was speaking in mean " gaining large amounts of benefit after the sum of all the parts come together"
Hans lol. kids...
yeah nah man
please dont simplify thing do it more complex
I'm so confused by this almost combative tone you have taken in response to Joshua Bardwell's and UAVfutures videos. If you really wanted to offer a real response to them you would address the benefits of stretched vs. X vs. wide layouts as this was more along the lines of what they were addressing and might actually further the conversation. That you've gone so far off topic is just an indication that you almost entirely missed the point of their videos. Neither of them were arguing that properties of physics, fluid dynamics and the disk loading theory that you have presented would prevent a smaller/lighter quad from being able to move around a track faster or have a higher top speed - *in theory*. They were simply expressing why some *flight dynamics* make it easier to PILOT these heavier quads with faster track times - something you have almost completely glossed over. You also focused so hard on Joshua's use of the term "camera uptilt angle" which is indeed a confusing term when all he meant (and was clear from his video) was something more like "frame tilt angle" ... but camera uptilt angle is somewhat of a proxy for this. They were very clear that what they were expressing was an optimization of a pilot's skills and flight dynamics not the theoretical limits. For instance, Joshua's response was, in my mind, an excellent response to UAVFuture's video because it attempted to add a quantitative response to a qualitative observation ... you're making interesting videos ... they just really aren't relevant to either of the ones you're responding to. I assume the issues they refer to will ultimately become irrelevant as more racing specific PID profiles/logic are made to take this into account and then the theoretical limits you're chasing after would become more important.
I feel like, at some point, racers are going to need another means of controlling their quads... like foot pedals for dynamic pitch rates or something wacky like that - a means of maintaining ultra fine altitude control at extreme angles but being able to unlock that for tracks that require large vertical changes at varying speeds. QuadPedals(TM)
CesiumSalami this video was NOT a response to them. I said my last video that WAS a response to them was incorrect about many things I said. nonetheless I will make another video discussing what you say because it seems many did not understand
CesiumSalami multirotors are hugely unlikely to move toward collective pitch. that's just not how these things work. we already have CP helis and quads. they're a different category. I'll discuss my very small opinion about that as well.
That's fair. My apologies on perhaps adding to the frustration. I just had that video on my mind, I guess - which is a good thing. Getting people thinking that is. Thanks for the response.
@Kabab FPV - Oh. I don't mean adding any additional moving parts to the quad that actually control the pitch / angle of attack of the blades themselves - collective pitch doesn't really make any sense on a quad for sure ... I was referring to a control that allows the user to vary the rates on the pitch axis. Basically, the harder you pitch the quad forward at speed, you're effectively increasing the rates on your pitch axis (the quad becomes very touchy and overly responsive). During fast forward flight a pilot might benefit from turning down their rates but that would be detrimentally for certain maneuvers, so you leave your rates high. The extra control i'm talking about would just be a mechanism to change your rates or increase your expo dynamically and quickly. This would allow a user to, during extreme forward flight effectively increase the expo to allow for really fine altitude control but then back that off when larger variations are required. This would be software based entirely.... It would just be like a SUPER complicated and dynamic expo curve that responded to speed/tilt angle.
That would be very complicated and I feel too unpredictable to manage. When you're flying at a normal pitch of ~60deg, it's already less sensitive to pitch adjustments actually. Also, what you say would work if we had batteries that could sustain high amp draw. Without that, we can't keep it going forward like a set of wings can. I do however understand what you're saying. Maybe someone will invent some algorithm in time that will be able to manage what you say in a predictive manner. That being said, in order to sense angle with respect to anything, the accelerometer needs to be turned on. Accel sensors are not as fast as gyro sensors which will require significantly reduced gyro rates. That will hugely impact performance. Maybe the accel sensors will improve in time to allow this or someone will decide to put one outside the loop for just low rate sensing.
first
What the hat is this "over simplified" trying-to-be science? I dont see this as theory, more like hypothesis. Sorry.
motkoloko you could go ahead and just read the Wikipedia on the "Disk Loading Theory". note that it's labeled as a theory. this video is also NOT scientific. none of my videos are. I wish I had the time to do real science...
Hmm oh! Thanks for the tip :)
Thank you for this video! very informative. I wanted to argue everyone's point on a heavy quad going faster so bad. physics just doesn't work that way. inertia and wind resistance are our worst enemies!
I'd say moreso inertia, not so much wind resistance. We're usually not goin 100mph.
Kabab FPV true. but the future of the sport is freedom class and I know that doesn't have anything to do with this particular subject but when you get into a larger quad the wind resistance starts to affect it more and more. As we scale up aerodynamics start to play a huge roll.
Yeah I'm working on that actually. My preferred frame design is actually a huge hash tag pattern octo because it's super easy to repair and it's an octo so smaller blades spinning faster. The issue is that 8 sticks moving through the air is a huge aero issue...but it's highly repairable.
But isn't that going in the opposite direction implied by disk loading? Among rotary craft (no gliding), for endurance-per-gram, nothing beats a 1-rotor (straight up heli), because the r is squared in (PI * r^2). [OK endurance/heavy lift is not exactly relevant for racing, doesn't say anything about agility, but it exactly proves disk loading.]
PS -- congrats on your Evo HD frame winning Sebring for MAD_AIR. I know you know more about all this than I do!
Kabab FPV that sounds like it would have amazing authority in all directions due to the having 2 motors in front and 2 in back. I feel like it would be very easy to control altitude. I am intrigued!