I recently started messing with ducts, and built a pseudo-tootpick-cinewhoop out of a 2.5" 2s/3s rig I have. Before I added ducts, this thing flew through the air like a dream, it was super quiet and stealthy, but also a bit hard to maneuver through small areas. I 3d printed some ducts that are halfway in between being prop guards and ducts, and it has totally changed the feel of the quad, also it is VERY LOUD! I think its louder than my 5". Its like a siren in the air, i bet my neighbors from 2 blocks away can hear it! I'd like to know more about making silent quads, and cinewhoops, and the sacrifices and benefits you get from flying both. Right now i'm happy because I can do a bit more proximity flying with this build, but at the same time it might scare the subjects to have a really loud siren buzzing around them!
Other than the Powerpoint style presentation giving me PTSD from high school I love the knowledge you're bringing into the community. Keep up the good work, Chris. A+
Great work Chris, just great work, you've just helped the community immensely and probably boosted the profits of several ducted quad manufacturers :-)
Hi Chris. I fly most cinewhoops and can feel what you mean by momentum but to me it makes ducted cinewhoops fly more robotically. Also ducted cinewhoops have a much stronger tendency to get sucked into walls and drapes. They are also harder to fly smoothly when there is a breeze. So personally I prefer prop guards, not ducts.
I have this tendency to keep checking how much time is left in the video, so I can prepare to be sad when it's over.. lmao.. This is pretty great info.
For the longest time, there wasn’t any innovation in props, there was only some R&D into materials for rigidity/flexibility for longevity purposes which changed flight characteristics because of how they flex. DJI put a lot of thought into their props for their mavic series, they are efficient and insanely quiet compared to what was available at the time. I think props still have a little more ways to go, maybe you can tackle the different effects that prop diameter/thrust/pitch speed/weight/KV can have on the overall setup…..
Fascinating discussion, Chris! New subscriber here. I was just wondering about transplanting my BetaFPV cinewhoop guts into a new frame - but the new frame has wider ducts - the spacing of which I now understand is critical. Cheers!
Hey Chris. Awesome content as always! I would be very interested in a vibration analysis of the TP3 frame by Kabab, because it would be quite juicy to see how smaller, lighter frames behave.
Super interesting. I already knew "ducted" quads didn't work as ducts, but your point about drag makes perfect sense ! On an unrelated note, my main gripe about cinewhoops is weight. I live in the EU, and the 250g limit is becoming very important for this type of quads. At 250g or less, you can basically fly anywhere, while at 251g, you have to stay 150m away from any human being :) My problem is, I wouldn't fly in close proximity without ducts or prop guards, but these add weight, which makes it hard to stay under the limit :) Also, quiet props for cinewhoop would be great, as they is definitely louder than people expect.
As person who is not interested in anything cine related, this is much more than I ever thought that went into how they act differently, that's pretty interesting, and would make a lot more sense knowing this about how cinewhoop footage can be controlled so precisely I'm pretty excited about the frame, as that was 1. The first thing that got me interested in this kind of stuff, as well as 2. The thing that pretty much started this whole channel Now on a bit of a side note. I'm now sourcing all the parts for the build I'm putting together, with a lot of stuff on the way, and eventually I landed on the Roma F5 frame. Now I think it's pretty well designed, as assembling it was a breeze, but I'm pretty curious about how it would perform in the resonance testing. So now I kinda want to ask. Will you ever do testing on the Roma F5 frame as well in the future?
I have reached out to Diatone to talk about analysing some of their frames but haven't heard back. Without their support it will be difficult I'm afraid!
great video and just on time for my next build i got a set of prop guard for a 3in frame . Im going to take all this tips in consideration to make a good kwad thank u. also will like to know ur opinion on where should i put my battery on top or the bottom .
Man that was great. I watch a channel called rcmodelreview who covered ducted props, but not nearly so well (still a great channel though). Thank you for making this video. Wow so good!
I just ordered a squirt v2 slammed version, the body is shorter and also the ducts are shorter, you said at 16:50 that the quads with just prop guards will not have the beneficial effect of the different feel. Should I amend my order to the non slammed version? I'm not sure if the slammed squirt ducts would still have this effect or if they're basically just acting as ducts, but QSL the people I bought from tell me it is still a duct rather than a prop guard.
Hey Chris, this is one of my favorite vids so far, very interesting. I wonder if there was somehow a slot in the duct the blades spun in would this help get the efficiency benefits of the ducts without having to run a 1/4mm gap? Or cause more issues with turbulence within the duct? Also that video u linked was incredible! Loving all the in-depth science behind our hobby, keep it up Bud!
Im just learning about this, but if you created a looped motor around the duct with the foils curved inward toward the typical the point of rotation but not connected, would the tip vortices be in the middle, creating a vacuum of sorts in the center, causing the air to flow aroind al the blades and combine into the center of rotation?
Really appreciate the work you put into all this analysis. As an ex engineer (patent attorney now), I find it fascinating. However, this now does throw my choice of the next quad to buy into confusion! I was tempted with the iFlight Protek35 (which has guards, not ducts) for proximity flying around BMX riders on a race track (or tracking other similar moving objects), but maybe the Bumblebee (ducted) might be better if I want a more rapid/smoother deceleration through drag. Hmmmm
BMX riders go quite fast don't they? I'm not sure whether ducts are good for high speed chase shots. Once you get over a certain speed (~10mph) I think props with guards are probably the way to go.
@@ChrisRosser Very helpful follow up. Thanks. Yes, BMX riders can be very fast! So I take it duct are more appropriate for slow, controlled, cinematics. Noted.
I did some ducted fan experiments recently. I tried about 10 50mm props in a 3d printed duct and interestingly the props that looked like ducted fan props did slightly worse on average than the regular tapered props. The number of blades didn't make a difference past two. Tip clearance was less than 1 mm -- definitely achievable with a 3d printer. If you wanted, you could smear a thin layer of beeswax or a similar soft substance inside the duct and then spin up the props and achieve near zero tip clearance.
01:16 I have a theory on this. So, my whoops ALWAYS have issues decending from height when in a "hover" state (even pitch). If I try to decend by just lowering the throttle, the motors almost seem to not obey and I just sort of yaw-jitter and propwash down really slowly... Is the velocity of the air circulating around the ducts airfoil keeping the props from slowing down and sort of starting a thrust loop?
You`re kind of on the right track with the recirculation, but it has little to do with the props not being able to slow down: its a phenomenon called "vortex ring state" and is a problem for all quads and especially real helis. Its essentially when the air being pushed down somewhat matches the speed of the aircraft going down and therefore gets recirculated heavily, leading to a massive drop on lift. As said, all quads have that issue (partially what propwash is) ,Whoops are just affected by it more than other quads for a variety of reasons, part being high disk loading and low power to weight ratio. Edit: Also the flightcontroller trying to fight all of this is whats keeping the quad from descending as fast as you want it to.
Through experimentation I have found that the weight and moment of inertia properties of my props need to be suitably matched to my motor stator volume to minimize this effect. I run 1103 motors and 2" props on my whoop. Avan Blur props are too heavy by far and suffer thus effect greatly. Gemfan 2023 props are notably lighter with notably lower moment of inertia and handle vertical and steep descents quite smoothly by comparison.
Interesting question...waiting for Chris' answer to your doubt. I think its probably the lightweight airframe that with its severe drag coefficient , behaves more like a parachute.
@@yohfpv heh, not sure we are having the same problems, maybe though, I am on 2204 motors and 3" props on my cinesplore. Perhaps you are right, but ive tried several props, all ducted props by design, they all have the same problem. its not really propwash, its just, "i drop the throttle, iterm starts to wind up on all axis, props never reduce in speed, quad makes weird noises, then starts to shit its pants as it oscillates down from the heavens.
I'm with Benedikt on this one. I think it's vortex ring state and your prop blades may be stalling and recovering as you descend. Try shallower pitch props. That will increase your resilience to adverse inflow conditions.
Been experimenting with ducted quads and have noticed the air brake effect ! I'm wondering if there is a minimal duct design that will allow some efficiency gain without adding so much drag.
Great expose ! I thought I was having a aha! moment about why I found my tinywhoop much less drifty than the quads in liftoff and DRL but from your video, it's not the explanation. It's got prop guards rather than ducts so maybe it's more to do with its small weight. I'll soon be flying a Geprc baby crocodile 4 so I'll find out how close the simulators are.
Very interesting and exciting to watch Chris! I learned something new. :) I have a question. I have a cinelog25 and it's annoying that it shakes well when there is slight wind. Is it because there is almost no duct?
Really good, it will be interesting if you can make a part 2 and have a look at the racewhoop of free zillion. Now HGLRC sell the racewhoop with the partnership of free zillion maybe they will like that you make a review of there products🤔. I have also made a design myself and was able to improve the air flow/thrust of the duct 906g at 415watts with 2203.5 3600kv on 4s and hskrc3045 props, the probleme most of us see is we get alot of desync and yaw propwash but some user with AIO have no probleme and they can fly them like a freestyle drone. So if you are interested to give tip on how to tune them to be more freestyle friendly, it will be great.
Chris what motor and prop would you recommend for the AOS Cine35 evo. I bought a frame kit from the CNC outfit in Canada. Thanks. Lots of great work and information on your site I really enjoy and appreciate it! Yours is the only site I am a Patreon of.
Hi. Thx for the video. I am noob in drones , and I have issue with the prop blades friction with the duct. How to fix that. Should I reduce the size of the blades
The tip clearance is super intesting. I gave up on tip clearance early on and just asumene everything were running are psudo ducts. Within 2mm is fine.
The biggest thing I realised looking into this is that tip clearance isn't really responsible for cinewhoop handling. It doesn't matter that much. As you say within a few mm is fine. 👍
With quads flying foward the duct does not see straight air inflow. An angled air flow is meeting the duct. As far as I know this creates a momentum trying to level the quad (by the lift generated on the airfoil form of front part of the duct). Doesn't that decrease effciency and top-speed whilst it is another stabilizing factor?
You are correct that ducted quads are less efficient than a comparable open prop quad. They are also heavier and slower. But if you need a high drag flight feel you accept the compromises.
In the first slide are the blue arrows flow or thrust? Cause those would be opposite. In other words the Kort nozzle the lift would actually add to the thrust.
a lot of light weight props seem to use prandtl propulsion they have a lot of negative twist in them the lift distribution isn't elliptical but more like a normal distribution / bell curve (bsld - bell shaped lift distribution) the effect is reduced drag and with that faster spoolup i guess, more flow, quieter the wingtip vortecies aren't at the tip on these props, but about 1/3 of one blade length inward the wingtips outward of the vortecies act similar to winglets, just that they are flat (dihedral wise) since the airfoils at the tips are tilted down, the lift vector points forward, producing induced thrust bsld wings are ~22% larger than elliptical ones, for the same lift coefficient
Interesting. For quadcopter applications I would think that the requirement for thrust would push us to sacrifice some efficiency for more thrust for a given prop size? I don't know if the efficiency gain is worth making the prop 22% bigger with all the commensurate penalties in terms of MOI.
@@ChrisRosser it is a bit of a brain twister, since a elliptical wing of the same span has less drag than the bsld ones and the L/D is better in that case bsld is the lowest drag solution for a given structural weight (root bending moment), while elliptical is the lowest drag for a given span i still don't fully understand applications for the different types if we look at the developements in prop design, it has gone away from bullnose and the likes a reason might be, that not only the thrust is important, but how quickly it can be produced / switched between different amounts a fast spoolup would help the fc do it's job fighting propwash and other oscillations that might be even more important than going fast, it helps with attitude and altitude control, taking out physical "lag" while changing throttle input a lot of fixed wing designers / developers object to bsld and swear by the elliptical lift distribution
Insightful and valuable information. I have been designing my own cinewhoop and its nice to learn more. What about integrating duct and prop to get the clearance issue (rotating duct)
Rotating prop rings are very tricky for props that rotate at such a high RPM. Either you would need a lot of blades (which would eliminate any efficiency benefit) or to use a super high performing material that is stiff enough not to deform and break.
You should check out NASA research about Prantl-D wing. Al Bower at NASA did a lot of research on Wings and Bird flight. He figured out that the same optimization for the wing also works for the propeller. In his version the vortex happens about 2/3 of the way out. So I don't know if this is also improved by a duct. But even without you should get better thrust.
Great topic and just in time. I've been designing ducts for my cinewoop (fun project to force me to learn Fusion360.) I've been trying to get the ducts close, but not THAT close... Now I know I won't get the "true" benefits of ducts and can just focus on getting some of the cinewoop "feel" and prop/subject protection.
I would say based on what I know now that trying to get super tight tip clearance is unnecessary. So I think you're taking the right approach. Go for feel.
Thank you very much for this great presentation. I was actually hoping to get insights which will solve the issue I have with my Bumblebee V2. I switched the motors to T-Motor 2203.5 (2850kv). 6s Battery and HQ Prop 8 Blade duct props. I am experiencing desyncs eventhough I set all the settings to fight desyncs and even more I experience a very strange behavior of the quad. When flying around the quad doesn’t react properly on my throttle inputs anymore. When lowering the throttle it just does not regulate down the throttle. It is very difficult to make quick changes in altitude like this. Sometimes it even increases throttle even when my stick is at zero already. I thought this could probably also be an aerodynamic problem. Maybe that because of the quad basically flying only at lets say 15 degrees angle the propellers get very turbulent air at the intake because the flight direction is really not equal to the direction the ducts look. This seems to be very suboptimal innmy opinion. But unfortunately I did not study aerodynamics and as mentioned I did not find anything which helped to solve that issue on the net. Any idea?
hey dude, love your videos. just finished up tuning my first build ( 6s shwendrones squirt ) while following your video. it would be so helpful to see your take on a 3" cinewhoop tuning. my quad is fly nicely, but suffering from yaw washout pretty bad. any tips ?
Ah, it's a 3" cinewhoop so yaw washout is common with heavy cameras. Make sure you are flying props out and if that doesn't help consider a Cine35. The 3.5" props are a much better platform for heavier cameras like the Hero 8/9/10/11.
Really useful yet again 😁 I've always fancied doing a modified ducted y6. I don't suppose you've ever come across data for two contra rotating props in a duct?
All great information and accurate. Every tool has a specific job in FPV, there is no one size fits all in this hobby sadly. There is too much missinformation being spread, especially from "tech influencers" who really have no business giving advice about particular products.
Would love to get your take on push vs pull in regards cine whoop design. And while we're on the topic, reverse rotation vs standard. I'm aware of the practical arguments (carpets dont get stuck and dirt dont get on your cam) but am curious if there is tangible improvement in flight performance in some shape or other.
Why there are no two-bladed ducted fans? Can I make EDF more efficient for fixed wing by following same efficiency principle (lower kV motor + larger and minimum bladed prop)? Looking for long range cruiser wing with EDFs (possibly differential thrust like B2 or Horten Ho 229).
EDFs tend to need to get a lot of thrust out of a small diameter. So they use lots of steep blades and the duct helps reduce the efficiency penalty of doing that. To get equivalent thrust from a 2 blade prop the diameter would need to be much greater.
@@ChrisRosser Thanks Chris for very clear explanation. If EDF trades efficiency for size, can proper duct design compensate that penalty at least up 80-90%?
Thanks Chris. Very good Information. Just one thing: if you want to fly close to people with a cinewhoop, ducts or prop protection are nice to have. But doesnt it make the quad much louder? The bigger ducted cinewhoops are rediculessly loud. Draws too much attention, considering its mostle not legal to fly in populated areas near people.
Typically cinewhoops are loud due to the high disc loading. They have 3 inch props but weigh as much as a 5 inch quad sometimes. I think that makes them louder in a hover. At full throttle I think a 5inch is louder than a cinewhoop though.
@@ChrisRosser where did you come from? Lol you just showed up like 2 months ago and really changed the community for the better! Unless you had another channel or something I am not aware of.
Thanks for this video Chris. It’s excellent - very educational. Thinking about your comments on wing tips, would wing tips on racing quad propellors improve performance, while adhering to the 5.2inch max prop diameter regulation? I’d be very interested to see whether this would improve or hinder the speed of top racing pilots. What’s your view?
Hi, I understand that thin prop guards are not ducts, but when do they start acting as ducts, is there a specific diameter to height ratio where the quad starts feeling like a ducted cinewhoop? Also Thank you very much for your videos, finding science based infos or at least the explanation for the rules of thumb that are accepted by everyone just got a lot easier.
That is a great question. I would say that once the ducts extend significantly above and below the blades they will start to cause the flow to have to flow vertically. I imagine there will be diminishing returns above a certain height and a somewhat smooth transition between ducts and prop guards as the duct gets shorter.
If we were to machine a groove in the centre of the duct, And the propelors interfere fit the duct so we would ned to bend them until the were in the groove,and therefore have tip clearance, what effect would this have on the performance of the duct.
I think the biggest issue you would have is holding the tolerances in manufacturing you would need to make that work with plastic ducts. If they interfere too little you'll get no benefit. If they interfere too much you'll smoke motors.
Hi Chris, me and many of my friends are observing strange phenomenon in cinewhoops. When cruising forward and then leveling with throttle command at 0, cinewhoop tends to rise altitude. It happens also due to wind. Only thing that I was able to notice is that 3 motor are spinning in this case at high rpm, and one is spinning at idle rpm (2k-3k rpm). Is this possible that some unwanted lifting force is created at edge of the duct forcing FC to fight with it?
You will cause the ducts to stall when pitching level with no throttle. That will create a lot of buffeting. As the flight controller fights that motors will increase in throttle and may cause the quad to climb a little. Particularly if air mode is on.
Although toroidal fans are not a new idea but a old one reinvigorated the concept of making them more plane's prop is,. However this added to ducts or impellers for in flight or underwater or even pump or air conditioning ducts can make for interesting science. Arcamedis would be happy at how far his irrigation screw as came.
hi, great vid thankyou. all my friends think u r over thinking things i really cant wait to get your frame and prove em wrong. all my builds fly better then most my club and they dont no why. well coz i listen to peeps like u mate lol. im in u.k so hope we get a good deal on the frame lol thanks again
Are you 100% sure your math on vingtip vortex and distance from wingtip to ducts are correct? I see a noticable increase in flight time, with over a full minute more flight time with ducts vs no ducts, how is this not added thrust? This was with a full mm between wingtip and duct. I hope you give some answer to this. Always very interesting to watch your programs, keep it up Chris!
I'm pretty confident on that maths and I'm not the first to put forward that ducts on cinewhoops don't have tight enough tip clearance to get a benefit. In your testing did you use *exactly* the same quad, with the same battery, motors, camera angle, all up weight, props, go pro. Did anything about the build change between no ducts and ducts? Did you fly as close to exactly the same as possible? Was it windy one day and not the next?
@@ChrisRosser When I did those tests it was the same cinewhoop, 2 packs no ducts, then same two battery packs after charging with ducts. So ALUW with ducts was increased by the weight of the ducts. Still flew much longer. Weather did not change in the half hour or so it took to charge the batteries and put on the ducts. No wind, same temperature. Flight path was just around and around my garden at constant same speed, to make flight path as identical as possible. This leads me to believe that there is something going on here. I dont know if its the math that can not be scaled down to this size with the same accuracy, or what. But I get increased flight times, using ducts with ca 0.2mm (Brand new, newly grinded) up to around 1mm spacing. This is using Gemfan D76-5 props.
@@dragonwingfpvbyespenlossiu3808 I'd love you to put together a short video on this. Does anyone else have the same experience? +1minute is a huge increase in flight time.
@@ChrisRosser One minute is a huge difference. Hence my first comment, cause I am trying to make sense of it. And only thing I am left with, after deducted reasoning, is the ducts do still create some lift, even with a gap of up to 1 mm. I can put together a video, hopefully sometime next week, else the following week.
Hi, I asked you this question on your video to props too, but dont know where this fits better and where you will read it, so I copied it here to, hope that is okay: I asked myself all the time how to think about this on my Cinewhoop: To begin with: I have a squirt V2 at home and also I am just designing my own "megas-quirt", that fits 3.5" (89mm) props, as my Squirt is barely holding itself in the air with a Hero 8 and a 1300mAh 4s lipo. Now to my question: How do you think that multiple blades change the therory. By that I mean the 6- or 8-bladed HQ props, or the much steeper Gemfan D76 or sth like this. My testing tells me, that two props that both are called to have a pitch of 3 aren't really comparable, doesnt matter whitch size (3", 5", ...). In the cinewhoop-part also the diffrent blade-count makes everything even more uncompareable. I really have problems to compare a Gemfan D90 (3 bladed prop, pitch "3") to a HQ 89mmX8 (also pitch of "3") but they clearly are diffrent in their steppness-angle and will poth have very diffrent thrust. toothpick-class: Gemfan for example has a 3018-2 prop (biblade) and a 3016-3 (triblade), I also cant tell in this case which prop I could expect to have more thrust. The issue is, that we often dont have real numbers to calculate with or alternatively have simulation-values or static-bench test from the manufacture himself (1st hand). Sometimes I have the feeling, the manufacuters dont use the pitch-value to tell us how steep the balde is, rather to tell how much thrust they think the prop makes compared to their other props on the market. By adjusting the pitch value they use for marketing so they can put their props in somewhat of an order they make comparison for us pretty rough, and practically impossible to compare to other companies. Did/Do you think/feel the same as I do, or do you understand my problem? If so, do you have any idea how we could interpret these values we get from the manufactures, or do anything about it other than just buying a ton of props just to find out that 99% arent the ones we where looking for? Thank you so much for your videos, it is great to understand such topics in greater detail, love it, keep it up!
Comparing props is difficult because they are not fully specified by the manufacturers. Their performance is also very dependent on your AUW and flight style. I would suggest trying a prop and then asking yourself what you want more of: thrust? smoothness? efficiency in hover? efficiency in fast forward flight. Then use the info in the props video to move you in the right direction. E.g. more thrust = more blades or steeper pitch (but steeper pitch may be less smooth). more smoothness = shallower pitch It is not really possible in my view to pick the perfect prop just by looking on the web. But it is also not necessary to just buy every prop and try them all. You can take a more focused approach. I hope this helps.
Your inputs about the physics and science of quadcopters is beyond an ordinary hobbyist would take time to digest. It has been helpful to us engineers. Hopefully you can share about the flight dynamics of different kinds of frame configurations.
😍 I love this side of fpv , I will build one After everything get settled in India where covid is just dominating everything. 😷🤒 Do u have any website or any forum where I can ask some queries ?🤓
Your best bet to get info would probably be joining some discord servers. UAVfutures and MrSteele have the two of the biggest FPV related servers I think
So theoretically speaking, if one wants a quad's props to have no vortex formation, having specially molded propellers that look like those circled toy props is probably the easiest approach because it's got no gap at all. ae01.alicdn.com/kf/HTB1Cz6PIXXXXXcCXFXXq6xXFXXXj/HM-plane-circled-three-propeller-blades-circle-round-the-propeller-blade-aperture-2MM-DIY-model-remote.jpg I can easily see how someone can take the time to make a propeller mould that results in a cast with a specially shaped ring fused to the blade tips, though centripetal force might be an issue with deformation of the ring, so I think having more than 6 blades to provide more attachment points for the ring is the best way to go, I'd love to see someone actually this out, then there's the whole other issue with gyroscopic precession.
You are correct. For high RPMs you need a lot of blades to support the ring and more blades are less efficient so you end up losing some/all of the benefit of the ring.
I've enjoyed your videos. There are cinewhoop specific props (Gemfan & HQ Prop) that are bullnose with a consistent chord length. These type of props matched with some ducts require "grinding in" before being able to fly. It is possible to properly size props and 3D printed ducts for minimum clearance. I have found that 3D printed materials have some flexibility and props stretch so the static prop gap will appear to actually be larger than when in flight. I have been playing with airfoil duct designs with some success and believe it is possible to further develop cinewhoop ducts to overcome many of the limitations you describe in this video. Here are the short airfoil ducts that I designed and would be happy to send your the STL files if you wish to try them out. milehigh3d.com/shop/ols/products/pro-af-76mm-duct-kit-for-squirt-v2
Thanks for the link. Based on the images on that page your tip clearance is too large (~1mm) to be getting any thrust or efficiency benefit from the duct. The prop stretching is an interesting idea I would imagine given the large range of rpm a consistent clearance is going to be impossible to achieve. Can you put tape inside the duct and go fly to prove you are getting the clearances you need in flight? Regardless, I'm sure it still gives a great benefit in terms of feel for cinewhoop applications.
![Seungmin "그렇게, 천천히, 우리(As we are)" | [Stray Kids : SKZ-PLAYER]](http://i.ytimg.com/vi/kAzmhLHePqU/mqdefault.jpg)
Between you and UAV Tech I literally think my brain got bigger.
Yeah, those are the videos I watch more than once and pause and skip back a lot. 😁
I agree ☝️
@@mihavuk LOLLL I hear you on the pause and rewind. I'll sit and stare into space often times just to let my brain catch its breath lol
All your videos felt like one of my mechanical engineering classes, but for FPV and free knowledge. Thank you for all of the effort
Glad to help!
I recently started messing with ducts, and built a pseudo-tootpick-cinewhoop out of a 2.5" 2s/3s rig I have. Before I added ducts, this thing flew through the air like a dream, it was super quiet and stealthy, but also a bit hard to maneuver through small areas. I 3d printed some ducts that are halfway in between being prop guards and ducts, and it has totally changed the feel of the quad, also it is VERY LOUD! I think its louder than my 5". Its like a siren in the air, i bet my neighbors from 2 blocks away can hear it! I'd like to know more about making silent quads, and cinewhoops, and the sacrifices and benefits you get from flying both. Right now i'm happy because I can do a bit more proximity flying with this build, but at the same time it might scare the subjects to have a really loud siren buzzing around them!
Interesting. I've been thinking of a cinewhoop with as low dB as possible.
I wonder if there's any data
Other than the Powerpoint style presentation giving me PTSD from high school I love the knowledge you're bringing into the community. Keep up the good work, Chris. A+
How does the lift generated by the Kort nozzle oppose thrust? They are clearly pointing in the same direction in the slide at 1:00. To the right.
U bet im getting a frame if you design it💯 cant wait
Great work Chris, just great work, you've just helped the community immensely and probably boosted the profits of several ducted quad manufacturers :-)
No worries! Some people need ducts some need open props. I just want to make sure people get the right thing for what they want to do.
Hi Chris. I fly most cinewhoops and can feel what you mean by momentum but to me it makes ducted cinewhoops fly more robotically. Also ducted cinewhoops have a much stronger tendency to get sucked into walls and drapes. They are also harder to fly smoothly when there is a breeze. So personally I prefer prop guards, not ducts.
Can’t believe I just discovered this video. Hooked love the information and presentation. Can not wait to grind through the whole series
I have this tendency to keep checking how much time is left in the video, so I can prepare to be sad when it's over.. lmao.. This is pretty great info.
Thanks Mike. Very kind of you!
Amazingly great informative video my dude, I'm so thankful of the amazing people we have in this community
Same here!
Thank you for giving us some actual science-ing in this hobby!
You're very welcome! Hope you enjoy my other videos!
For the longest time, there wasn’t any innovation in props, there was only some R&D into materials for rigidity/flexibility for longevity purposes which changed flight characteristics because of how they flex.
DJI put a lot of thought into their props for their mavic series, they are efficient and insanely quiet compared to what was available at the time.
I think props still have a little more ways to go, maybe you can tackle the different effects that prop diameter/thrust/pitch speed/weight/KV can have on the overall setup…..
Have you checked out this video? ruclips.net/video/epJ6L9MaXOQ/видео.html
90 percent of "ducts" on the market today are glorified prop guards.
Fascinating discussion, Chris! New subscriber here. I was just wondering about transplanting my BetaFPV cinewhoop guts into a new frame - but the new frame has wider ducts - the spacing of which I now understand is critical. Cheers!
Enjoy your insights. We needed this expertise in the industry sooner.
soo detailed video, hats to you man..! and keep up the good work
Thanks, will do!
Hey Chris. Awesome content as always!
I would be very interested in a vibration analysis of the TP3 frame by Kabab, because it would be quite juicy to see how smaller, lighter frames behave.
Great suggestion! I'll ask Bob, I'm sure he would be keen to see how it looks.
Super interesting. I already knew "ducted" quads didn't work as ducts, but your point about drag makes perfect sense !
On an unrelated note, my main gripe about cinewhoops is weight. I live in the EU, and the 250g limit is becoming very important for this type of quads. At 250g or less, you can basically fly anywhere, while at 251g, you have to stay 150m away from any human being :) My problem is, I wouldn't fly in close proximity without ducts or prop guards, but these add weight, which makes it hard to stay under the limit :)
Also, quiet props for cinewhoop would be great, as they is definitely louder than people expect.
youre an encyclopedia
great work
best fpv channel and ive seen them all
As person who is not interested in anything cine related, this is much more than I ever thought that went into how they act differently, that's pretty interesting, and would make a lot more sense knowing this about how cinewhoop footage can be controlled so precisely
I'm pretty excited about the frame, as that was 1. The first thing that got me interested in this kind of stuff, as well as 2. The thing that pretty much started this whole channel
Now on a bit of a side note. I'm now sourcing all the parts for the build I'm putting together, with a lot of stuff on the way, and eventually I landed on the Roma F5 frame. Now I think it's pretty well designed, as assembling it was a breeze, but I'm pretty curious about how it would perform in the resonance testing. So now I kinda want to ask. Will you ever do testing on the Roma F5 frame as well in the future?
I have reached out to Diatone to talk about analysing some of their frames but haven't heard back. Without their support it will be difficult I'm afraid!
I'm really enjoying these videos thanks 😊👍 I've recently switched my shendrone squirts to slammed ducts, they are much better.
great video and just on time for my next build i got a set of prop guard for a 3in frame . Im going to take all this tips in consideration to make a good kwad thank u. also will like to know ur opinion on where should i put my battery on top or the bottom .
Battery on top is my preference for a more central centre of mass. 👍
Man that was great. I watch a channel called rcmodelreview who covered ducted props, but not nearly so well (still a great channel though).
Thank you for making this video. Wow so good!
I just ordered a squirt v2 slammed version, the body is shorter and also the ducts are shorter, you said at 16:50 that the quads with just prop guards will not have the beneficial effect of the different feel.
Should I amend my order to the non slammed version? I'm not sure if the slammed squirt ducts would still have this effect or if they're basically just acting as ducts, but QSL the people I bought from tell me it is still a duct rather than a prop guard.
I would say even shorter ducts will still have plenty of duct effect.
Hey Chris, this is one of my favorite vids so far, very interesting.
I wonder if there was somehow a slot in the duct the blades spun in would this help get the efficiency benefits of the ducts without having to run a 1/4mm gap? Or cause more issues with turbulence within the duct?
Also that video u linked was incredible!
Loving all the in-depth science behind our hobby, keep it up Bud!
I think you would still get a tip vortex forming in the slot if the gap wasn't super tight. Glad you like the video!
Im just learning about this, but if you created a looped motor around the duct with the foils curved inward toward the typical the point of rotation but not connected, would the tip vortices be in the middle, creating a vacuum of sorts in the center, causing the air to flow aroind al the blades and combine into the center of rotation?
Really appreciate the work you put into all this analysis. As an ex engineer (patent attorney now), I find it fascinating. However, this now does throw my choice of the next quad to buy into confusion! I was tempted with the iFlight Protek35 (which has guards, not ducts) for proximity flying around BMX riders on a race track (or tracking other similar moving objects), but maybe the Bumblebee (ducted) might be better if I want a more rapid/smoother deceleration through drag. Hmmmm
BMX riders go quite fast don't they? I'm not sure whether ducts are good for high speed chase shots. Once you get over a certain speed (~10mph) I think props with guards are probably the way to go.
@@ChrisRosser Very helpful follow up. Thanks. Yes, BMX riders can be very fast! So I take it duct are more appropriate for slow, controlled, cinematics. Noted.
I did some ducted fan experiments recently. I tried about 10 50mm props in a 3d printed duct and interestingly the props that looked like ducted fan props did slightly worse on average than the regular tapered props. The number of blades didn't make a difference past two. Tip clearance was less than 1 mm -- definitely achievable with a 3d printer. If you wanted, you could smear a thin layer of beeswax or a similar soft substance inside the duct and then spin up the props and achieve near zero tip clearance.
01:16
I have a theory on this. So, my whoops ALWAYS have issues decending from height when in a "hover" state (even pitch). If I try to decend by just lowering the throttle, the motors almost seem to not obey and I just sort of yaw-jitter and propwash down really slowly... Is the velocity of the air circulating around the ducts airfoil keeping the props from slowing down and sort of starting a thrust loop?
You`re kind of on the right track with the recirculation, but it has little to do with the props not being able to slow down: its a phenomenon called "vortex ring state" and is a problem for all quads and especially real helis. Its essentially when the air being pushed down somewhat matches the speed of the aircraft going down and therefore gets recirculated heavily, leading to a massive drop on lift. As said, all quads have that issue (partially what propwash is) ,Whoops are just affected by it more than other quads for a variety of reasons, part being high disk loading and low power to weight ratio. Edit: Also the flightcontroller trying to fight all of this is whats keeping the quad from descending as fast as you want it to.
Through experimentation I have found that the weight and moment of inertia properties of my props need to be suitably matched to my motor stator volume to minimize this effect. I run 1103 motors and 2" props on my whoop. Avan Blur props are too heavy by far and suffer thus effect greatly. Gemfan 2023 props are notably lighter with notably lower moment of inertia and handle vertical and steep descents quite smoothly by comparison.
Interesting question...waiting for Chris' answer to your doubt.
I think its probably the lightweight airframe that with its severe drag coefficient , behaves more like a parachute.
@@yohfpv heh, not sure we are having the same problems, maybe though, I am on 2204 motors and 3" props on my cinesplore. Perhaps you are right, but ive tried several props, all ducted props by design, they all have the same problem. its not really propwash, its just, "i drop the throttle, iterm starts to wind up on all axis, props never reduce in speed, quad makes weird noises, then starts to shit its pants as it oscillates down from the heavens.
I'm with Benedikt on this one. I think it's vortex ring state and your prop blades may be stalling and recovering as you descend. Try shallower pitch props. That will increase your resilience to adverse inflow conditions.
Been experimenting with ducted quads and have noticed the air brake effect ! I'm wondering if there is a minimal duct design that will allow some efficiency gain without adding so much drag.
Great expose ! I thought I was having a aha! moment about why I found my tinywhoop much less drifty than the quads in liftoff and DRL but from your video, it's not the explanation. It's got prop guards rather than ducts so maybe it's more to do with its small weight. I'll soon be flying a Geprc baby crocodile 4 so I'll find out how close the simulators are.
Great video, thanks for spending the time to make this
My pleasure!
would a stator help with sideslip in the unducted case? or would the "flow rectification" just cost drag/less-thrust?
I like your new video where you tested props with and without ducs and found they ducs annihilated the drone efficiency and thrust.
Very interesting and exciting to watch Chris! I learned something new. :) I have a question. I have a cinelog25 and it's annoying that it shakes well when there is slight wind. Is it because there is almost no duct?
Really good, it will be interesting if you can make a part 2 and have a look at the racewhoop of free zillion. Now HGLRC sell the racewhoop with the partnership of free zillion maybe they will like that you make a review of there products🤔. I have also made a design myself and was able to improve the air flow/thrust of the duct 906g at 415watts with 2203.5 3600kv on 4s and hskrc3045 props, the probleme most of us see is we get alot of desync and yaw propwash but some user with AIO have no probleme and they can fly them like a freestyle drone. So if you are interested to give tip on how to tune them to be more freestyle friendly, it will be great.
Thanks Chris - I definitely learned something today
Glad to help
I read this comment as soon as I said that.
Chris what motor and prop would you recommend for the AOS Cine35 evo. I bought a frame kit from the CNC outfit in Canada. Thanks. Lots of great work and information on your site I really enjoy and appreciate it! Yours is the only site I am a Patreon of.
2004 size motors with a 3.5" prop, perhaps the HQ T90mm X3.
@@ChrisRosser Have you tested any AXI motors?
I'm loving all these science based quad videos!!!
Glad you like them!
Hi. Thx for the video. I am noob in drones , and I have issue with the prop blades friction with the duct. How to fix that. Should I reduce the size of the blades
Just a side note, would it be beneficial to have the outside of the cinewhoop rounded for side wind's?
The tip clearance is super intesting. I gave up on tip clearance early on and just asumene everything were running are psudo ducts. Within 2mm is fine.
The biggest thing I realised looking into this is that tip clearance isn't really responsible for cinewhoop handling. It doesn't matter that much. As you say within a few mm is fine. 👍
woow, that opened my mind :D never thougth about the effect of duct drag before! but its obvious when you know it
Nice to hear there are actual physics to back up what I experience daily :).
Can’t wait to see your frame..
With quads flying foward the duct does not see straight air inflow. An angled air flow is meeting the duct. As far as I know this creates a momentum trying to level the quad (by the lift generated on the airfoil form of front part of the duct). Doesn't that decrease effciency and top-speed whilst it is another stabilizing factor?
You are correct that ducted quads are less efficient than a comparable open prop quad. They are also heavier and slower. But if you need a high drag flight feel you accept the compromises.
So what if you created a drone with ducted propellers angled so they face straight forward when flying?
In the first slide are the blue arrows flow or thrust? Cause those would be opposite. In other words the Kort nozzle the lift would actually add to the thrust.
a lot of light weight props seem to use prandtl propulsion
they have a lot of negative twist in them
the lift distribution isn't elliptical but more like a normal distribution / bell curve (bsld - bell shaped lift distribution)
the effect is reduced drag and with that faster spoolup i guess, more flow, quieter
the wingtip vortecies aren't at the tip on these props, but about 1/3 of one blade length inward
the wingtips outward of the vortecies act similar to winglets, just that they are flat (dihedral wise)
since the airfoils at the tips are tilted down, the lift vector points forward, producing induced thrust
bsld wings are ~22% larger than elliptical ones, for the same lift coefficient
Interesting. For quadcopter applications I would think that the requirement for thrust would push us to sacrifice some efficiency for more thrust for a given prop size? I don't know if the efficiency gain is worth making the prop 22% bigger with all the commensurate penalties in terms of MOI.
@@ChrisRosser it is a bit of a brain twister, since a elliptical wing of the same span has less drag than the bsld ones and the L/D is better in that case
bsld is the lowest drag solution for a given structural weight (root bending moment), while elliptical is the lowest drag for a given span
i still don't fully understand applications for the different types
if we look at the developements in prop design, it has gone away from bullnose and the likes
a reason might be, that not only the thrust is important, but how quickly it can be produced / switched between different amounts
a fast spoolup would help the fc do it's job fighting propwash and other oscillations
that might be even more important than going fast, it helps with attitude and altitude control, taking out physical "lag" while changing throttle input
a lot of fixed wing designers / developers object to bsld and swear by the elliptical lift distribution
Insightful and valuable information. I have been designing my own cinewhoop and its nice to learn more. What about integrating duct and prop to get the clearance issue (rotating duct)
Rotating prop rings are very tricky for props that rotate at such a high RPM. Either you would need a lot of blades (which would eliminate any efficiency benefit) or to use a super high performing material that is stiff enough not to deform and break.
@@ChrisRosser kids toys have props with built in protection. Not ducts, but prevents injury.
Would like to see how the cinewhoop duct with a triple toroidal fan would work, and see these two science's progress together on drones. All the best.
You should check out NASA research about Prantl-D wing. Al Bower at NASA did a lot of research on Wings and Bird flight. He figured out that the same optimization for the wing also works for the propeller. In his version the vortex happens about 2/3 of the way out. So I don't know if this is also improved by a duct. But even without you should get better thrust.
For aos 5,5 v1,, what duct you recomend? Shendrone duct 85 prop or universal duct 5 from stan fpv?
Great topic and just in time. I've been designing ducts for my cinewoop (fun project to force me to learn Fusion360.) I've been trying to get the ducts close, but not THAT close... Now I know I won't get the "true" benefits of ducts and can just focus on getting some of the cinewoop "feel" and prop/subject protection.
I would say based on what I know now that trying to get super tight tip clearance is unnecessary. So I think you're taking the right approach. Go for feel.
Thank you very much for this great presentation. I was actually hoping to get insights which will solve the issue I have with my Bumblebee V2. I switched the motors to T-Motor 2203.5 (2850kv). 6s Battery and HQ Prop 8 Blade duct props. I am experiencing desyncs eventhough I set all the settings to fight desyncs and even more I experience a very strange behavior of the quad. When flying around the quad doesn’t react properly on my throttle inputs anymore. When lowering the throttle it just does not regulate down the throttle. It is very difficult to make quick changes in altitude like this. Sometimes it even increases throttle even when my stick is at zero already. I thought this could probably also be an aerodynamic problem. Maybe that because of the quad basically flying only at lets say 15 degrees angle the propellers get very turbulent air at the intake because the flight direction is really not equal to the direction the ducts look. This seems to be very suboptimal innmy opinion. But unfortunately I did not study aerodynamics and as mentioned I did not find anything which helped to solve that issue on the net. Any idea?
Great explanation!! Love the content
Thanks Luke!
hey dude, love your videos. just finished up tuning my first build ( 6s shwendrones squirt ) while following your video. it would be so helpful to see your take on a 3" cinewhoop tuning. my quad is fly nicely, but suffering from yaw washout pretty bad. any tips ?
Ah, it's a 3" cinewhoop so yaw washout is common with heavy cameras. Make sure you are flying props out and if that doesn't help consider a Cine35. The 3.5" props are a much better platform for heavier cameras like the Hero 8/9/10/11.
This is pretty much over my head, but I'm curious. Is it possible to fly one these in a light-weight custom made room that can lift into the air?
Really useful yet again 😁 I've always fancied doing a modified ducted y6. I don't suppose you've ever come across data for two contra rotating props in a duct?
Not yet! But I imagine they will work just fine and you'll still get the duct drag effect if that is what you are looking for.
How about a groove in the duct that encapsulates the tips of the propellers?
All great information and accurate. Every tool has a specific job in FPV, there is no one size fits all in this hobby sadly. There is too much missinformation being spread, especially from "tech influencers" who really have no business giving advice about particular products.
Fantastic content as always. Thank you!
Much appreciated!
Would love to get your take on push vs pull in regards cine whoop design. And while we're on the topic, reverse rotation vs standard. I'm aware of the practical arguments (carpets dont get stuck and dirt dont get on your cam) but am curious if there is tangible improvement in flight performance in some shape or other.
Great suggestions! Thank you for your comment Ronin. I've added them to my content list
so all my cinewhoop drone has propeller guard, not ducted
awesome video
Why there are no two-bladed ducted fans? Can I make EDF more efficient for fixed wing by following same efficiency principle (lower kV motor + larger and minimum bladed prop)?
Looking for long range cruiser wing with EDFs (possibly differential thrust like B2 or Horten Ho 229).
EDFs tend to need to get a lot of thrust out of a small diameter. So they use lots of steep blades and the duct helps reduce the efficiency penalty of doing that. To get equivalent thrust from a 2 blade prop the diameter would need to be much greater.
@@ChrisRosser Thanks Chris for very clear explanation. If EDF trades efficiency for size, can proper duct design compensate that penalty at least up 80-90%?
Thanks Chris. Very good Information. Just one thing: if you want to fly close to people with a cinewhoop, ducts or prop protection are nice to have. But doesnt it make the quad much louder? The bigger ducted cinewhoops are rediculessly loud. Draws too much attention, considering its mostle not legal to fly in populated areas near people.
Typically cinewhoops are loud due to the high disc loading. They have 3 inch props but weigh as much as a 5 inch quad sometimes. I think that makes them louder in a hover. At full throttle I think a 5inch is louder than a cinewhoop though.
Keep the great content coming!! Thank you!
You bet! New frame launch imminent 😁
@@ChrisRosser where did you come from? Lol you just showed up like 2 months ago and really changed the community for the better! Unless you had another channel or something I am not aware of.
Really good content, thanls for all your videos !
Glad you like them!
Thanks for this video Chris. It’s excellent - very educational. Thinking about your comments on wing tips, would wing tips on racing quad propellors improve performance, while adhering to the 5.2inch max prop diameter regulation? I’d be very interested to see whether this would improve or hinder the speed of top racing pilots. What’s your view?
Hi, I understand that thin prop guards are not ducts, but when do they start acting as ducts, is there a specific diameter to height ratio where the quad starts feeling like a ducted cinewhoop?
Also Thank you very much for your videos, finding science based infos or at least the explanation for the rules of thumb that are accepted by everyone just got a lot easier.
That is a great question. I would say that once the ducts extend significantly above and below the blades they will start to cause the flow to have to flow vertically. I imagine there will be diminishing returns above a certain height and a somewhat smooth transition between ducts and prop guards as the duct gets shorter.
Gosh I love your content. Now I now I wanna have a ducted quad… and why JB hates them!
Thanks! I don't think ducts suit JBs style. TBH they don't suit my style either but they definitely fulfil an important function in cinewhoops.
If we were to machine a groove in the centre of the duct, And the propelors interfere fit the duct so we would ned to bend them until the were in the groove,and therefore have tip clearance, what effect would this have on the performance of the duct.
I think the biggest issue you would have is holding the tolerances in manufacturing you would need to make that work with plastic ducts. If they interfere too little you'll get no benefit. If they interfere too much you'll smoke motors.
Hi Chris, me and many of my friends are observing strange phenomenon in cinewhoops. When cruising forward and then leveling with throttle command at 0, cinewhoop tends to rise altitude. It happens also due to wind. Only thing that I was able to notice is that 3 motor are spinning in this case at high rpm, and one is spinning at idle rpm (2k-3k rpm). Is this possible that some unwanted lifting force is created at edge of the duct forcing FC to fight with it?
You will cause the ducts to stall when pitching level with no throttle. That will create a lot of buffeting. As the flight controller fights that motors will increase in throttle and may cause the quad to climb a little. Particularly if air mode is on.
So good to have you in the hobbie mate, love the content and hope you stick around.
That's the plan!
@@ChrisRosser Can't wait to see what you come up with mate, hope you're having fun flying as well.
Great explanation
Although toroidal fans are not a new idea but a old one reinvigorated the concept of making them more plane's prop is,. However this added to ducts or impellers for in flight or underwater or even pump or air conditioning ducts can make for interesting science. Arcamedis would be happy at how far his irrigation screw as came.
Amazing physics appreciate your analysis
Hello can i remove ducts when on cloud149 when im in like windy?
Yes, that should help wih windy conditions.
@@ChrisRosser thanks
BRAVO!!!!! such interesting content!!!!!
Thank you!
never knew I needed this kind of information untill now , and now I totally do
Knowledge is power, and power is EVERYTHING! *Evil laughter*
I challenge you to talk about the sound/noise made by drones!
hi, great vid thankyou. all my friends think u r over thinking things i really cant wait to get your frame and prove em wrong. all my builds fly better then most my club and they dont no why. well coz i listen to peeps like u mate lol. im in u.k so hope we get a good deal on the frame lol thanks again
I take overthinking things as a compliment! I'll do my absolute best to get some frames stocked in UK for you.
@@ChrisRosser do u have an idea on a price? i will need to safe i rekon lol
Are you 100% sure your math on vingtip vortex and distance from wingtip to ducts are correct?
I see a noticable increase in flight time, with over a full minute more flight time with ducts vs no ducts, how is this not added thrust? This was with a full mm between wingtip and duct.
I hope you give some answer to this.
Always very interesting to watch your programs, keep it up Chris!
I'm pretty confident on that maths and I'm not the first to put forward that ducts on cinewhoops don't have tight enough tip clearance to get a benefit.
In your testing did you use *exactly* the same quad, with the same battery, motors, camera angle, all up weight, props, go pro. Did anything about the build change between no ducts and ducts? Did you fly as close to exactly the same as possible? Was it windy one day and not the next?
@@ChrisRosser When I did those tests it was the same cinewhoop, 2 packs no ducts, then same two battery packs after charging with ducts. So ALUW with ducts was increased by the weight of the ducts. Still flew much longer. Weather did not change in the half hour or so it took to charge the batteries and put on the ducts. No wind, same temperature. Flight path was just around and around my garden at constant same speed, to make flight path as identical as possible.
This leads me to believe that there is something going on here. I dont know if its the math that can not be scaled down to this size with the same accuracy, or what. But I get increased flight times, using ducts with ca 0.2mm (Brand new, newly grinded) up to around 1mm spacing.
This is using Gemfan D76-5 props.
@@dragonwingfpvbyespenlossiu3808 I'd love you to put together a short video on this. Does anyone else have the same experience? +1minute is a huge increase in flight time.
@@ChrisRosser One minute is a huge difference. Hence my first comment, cause I am trying to make sense of it. And only thing I am left with, after deducted reasoning, is the ducts do still create some lift, even with a gap of up to 1 mm.
I can put together a video, hopefully sometime next week, else the following week.
Maybe the duct drag creates more efficient changes in direction
Hi,
I asked you this question on your video to props too, but dont know where this fits better and where you will read it, so I copied it here to, hope that is okay:
I asked myself all the time how to think about this on my Cinewhoop:
To begin with: I have a squirt V2 at home and also I am just designing my own "megas-quirt", that fits 3.5" (89mm) props, as my Squirt is barely holding
itself in the air with a Hero 8 and a 1300mAh 4s lipo.
Now to my question:
How do you think that multiple blades change the therory. By that I mean
the 6- or 8-bladed HQ props, or the much steeper Gemfan D76 or sth like
this. My testing tells me, that two props that both are called to have
a pitch of 3 aren't really comparable, doesnt matter whitch size (3",
5", ...).
In the cinewhoop-part also the diffrent blade-count makes
everything even more uncompareable. I really have problems to compare a
Gemfan D90 (3 bladed prop, pitch "3") to a HQ 89mmX8 (also pitch of "3")
but they clearly are diffrent in their steppness-angle and will poth
have very diffrent thrust.
toothpick-class: Gemfan for example
has a 3018-2 prop (biblade) and a 3016-3 (triblade), I also cant tell in
this case which prop I could expect to have more thrust. The issue is,
that we often dont have real numbers to calculate with or alternatively
have simulation-values or static-bench test from the manufacture himself
(1st hand).
Sometimes I have the feeling, the manufacuters
dont use the pitch-value to tell us how steep the balde is, rather to
tell how much thrust they think the prop makes compared to their other
props on the market. By adjusting the pitch value they use for marketing
so they can put their props in somewhat of an order they make
comparison for us pretty rough, and practically impossible to compare to
other companies.
Did/Do you think/feel the same as I do, or do
you understand my problem? If so, do you have any idea how we could
interpret these values we get from the manufactures, or do anything
about it other than just buying a ton of props just to find out that 99%
arent the ones we where looking for?
Thank you so much for your videos, it is great to understand such topics in greater detail, love it, keep it up!
Comparing props is difficult because they are not fully specified by the manufacturers. Their performance is also very dependent on your AUW and flight style.
I would suggest trying a prop and then asking yourself what you want more of: thrust? smoothness? efficiency in hover? efficiency in fast forward flight.
Then use the info in the props video to move you in the right direction. E.g. more thrust = more blades or steeper pitch (but steeper pitch may be less smooth).
more smoothness = shallower pitch
It is not really possible in my view to pick the perfect prop just by looking on the web. But it is also not necessary to just buy every prop and try them all. You can take a more focused approach. I hope this helps.
Ty for the insight
Thank you for making those great videos.
thanks , another great video .
you inverted the direction of trust at the start
Your inputs about the physics and science of quadcopters is beyond an ordinary hobbyist would take time to digest. It has been helpful to us engineers.
Hopefully you can share about the flight dynamics of different kinds of frame configurations.
😍 I love this side of fpv , I will build one
After everything get settled in India where covid is just dominating everything. 😷🤒
Do u have any website or any forum where I can ask some queries ?🤓
Your best bet to get info would probably be joining some discord servers. UAVfutures and MrSteele have the two of the biggest FPV related servers I think
I hang around a few discord servers including those. @ChrisRosser
@@ChrisRosser thanks
What kind of monster would press 'dislike' on video like this?
Thank you. 👍 This also explains horrible wind sensitivity of cinewhoops, doesn't it?
Yes, exactly. The duct drag works the same. The cinewhoop will be carried with the wind.
.25mm! That's crazy!
Quack quack!
Brill..thanks..
So theoretically speaking, if one wants a quad's props to have no vortex formation, having specially molded propellers that look like those circled toy props is probably the easiest approach because it's got no gap at all.
ae01.alicdn.com/kf/HTB1Cz6PIXXXXXcCXFXXq6xXFXXXj/HM-plane-circled-three-propeller-blades-circle-round-the-propeller-blade-aperture-2MM-DIY-model-remote.jpg
I can easily see how someone can take the time to make a propeller mould that results in a cast with a specially shaped ring fused to the blade tips, though centripetal force might be an issue with deformation of the ring, so I think having more than 6 blades to provide more attachment points for the ring is the best way to go, I'd love to see someone actually this out, then there's the whole other issue with gyroscopic precession.
You are correct. For high RPMs you need a lot of blades to support the ring and more blades are less efficient so you end up losing some/all of the benefit of the ring.
at the core moment you miss-explained the shape job
they save fingers and hair surely.
Very true. Another good reason to have prop guards/ducts.
nice to know you fly like a freaking brain surgeon 😂 What if i duct-tape the front of the prop cage? Wouldn't that do the same thing?
It might well have the same effect if it forces the air to move vertically through the props rather than allowing it to go sideways.
👍👀🇭🇷
I've enjoyed your videos. There are cinewhoop specific props (Gemfan & HQ Prop) that are bullnose with a consistent chord length. These type of props matched with some ducts require "grinding in" before being able to fly. It is possible to properly size props and 3D printed ducts for minimum clearance. I have found that 3D printed materials have some flexibility and props stretch so the static prop gap will appear to actually be larger than when in flight. I have been playing with airfoil duct designs with some success and believe it is possible to further develop cinewhoop ducts to overcome many of the limitations you describe in this video. Here are the short airfoil ducts that I designed and would be happy to send your the STL files if you wish to try them out. milehigh3d.com/shop/ols/products/pro-af-76mm-duct-kit-for-squirt-v2
Thanks for the link. Based on the images on that page your tip clearance is too large (~1mm) to be getting any thrust or efficiency benefit from the duct. The prop stretching is an interesting idea I would imagine given the large range of rpm a consistent clearance is going to be impossible to achieve. Can you put tape inside the duct and go fly to prove you are getting the clearances you need in flight? Regardless, I'm sure it still gives a great benefit in terms of feel for cinewhoop applications.