🚀CO2 Powered... Propeller? Rocket?
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- Опубликовано: 14 янв 2018
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Tom's Video: • Air Powered... Propeller?
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To fix the end cap from coming off when you hold it, reverse the direction of the propeller or put left-hand threads on it.
Using Propellers you should have more gyroscopic stability, so it will less wiggle in the air.
The answer is the same difference between a rocket and a plane. You are using your compressed CO2 like a rocket but only getting the lift of a plane. The only thing your doing is adding resistance. If you used something like a piston engine or a turbo you could increase your duration and make it work more like a plane. If you shrunk the wings and did some weight reduction you could make it work more like a rocket also giving you more lift.
Consider trying this with a variety of prop diameters. Rocket efficiency increases with velocity, so the faster you can get the blade tips going, the more energy is being supplied to the propeller (with less energy remaining in the exhaust gas).
Another way to think about it is the fact that work = torque * rotation angle. A larger diameter propeller will provide more torque, while RPM may increase or decrease (the additional torque will help to increase RPM, while the increased mass (more accurately, its 'moment of inertia') and the increased drag will both act to reduce RPM.
At some propeller diameter, there should be an optimal point at which the work done on the propeller is greatest - giving you the most possible lift.
Try doubling the blade length with the nozzles staying at the same distance from the center, but with smaller diameters. This will lengthen the time over which the canister can release it's energy and also allow for faster blade tips. You also might want to have a varied rotor tilt so that every point along the rotor pushes the same amount of air during a single rotation.
Your prop will be much more efficient if it has some camber to it, and if it changes in pitch along its length (steep at the hub, and shallow near the tips). Have a look at some RC aeroplane props and try to mimic their profile.
Great work, though! I'm amazed that no CO2 leaked past the seal, and that the body held together. CO2 canisters are under a LOT of pressure!
If the air passages are 1mm in diameter, then even a huge pressure like 1000PSI inside the passage would be 1000 pounds per square inch, but a 1mm passage only has 0.001224502 square inches of area in cross section, so the force needed to hold that pressure for such a small channel is very small.
USWaterRockets
Yes, but I was more surprised that no gas got past the o-ring and into the main body, where the surface area is a lot greater.
It's possible that the o-ring did leak, but the main body does not appear to be pressure sealed, so that gas would simply vent through the seams where the printed parts mate. It probably is not a lot of gas, but you're right that area may indeed be leaking.
USWaterRockets
Yeah, I guess the leak rate out of the main body is a lot faster than the leak rate past the o-ring.
JMMC1005 yes, exactly. Was going to mention the same thing!
There where actually a few aircraft designed around this concept. Most notable the Hiller hornet. It is a helicopter that has no engine but instead has small ramjets on the end of each of the rotor blades. There where also a few that had a turbofan or turbojet engine inside of the main aircraft fuselage that routed the exhaust to the tips of the rotor blades. (more similar to what is shown in this video.) The idea was that without a motor spinning the propeller, there would be no need for a tail rotor because the net torque between the fuselage and rotor would be zero. These were called tip-jet helicopters.
I've played around with rocket powered helis in Kerbal and what I've found is that you get greater altitude with a straight rocket, for equivalent weight of fuel. IE one ton of fuel gets the greatest altitude when directly propelling the craft up, rather than spinning up a rotor. However, if max altitude isn't your goal, but max air time is, then heli rockets work very well. They are less efficient than a direct rocket drive, however it allows for the use of much smaller rocket motors, meaning less of your weight is rocket.
Why dont you try to do some sort of air turbine setup instead of the thrust system you have?
It's called a countersink! It is a bit for seating the skrew flush with your surface. The drill bit is not designed for that.
To solve the problem of the end cap falling of reverse the thread for your print. The rotation of the prop will act to tighten it. This principle is used in commercial trucks where wheel studs are threaded opposite hand threads on opposite sides of the truck.
If it hasnt been said, then I will say it. According to physics, every action has an equal but opposite reaction. So, having a gas(in this case co2) directly propelling the object would be more efficient because there are no additional steps. That gas would immediately result in thrust, whereas having the gas propel the blade, at lveast in this design, is much less efficient. The issue is that the gas is pushing towards the direction you want to go, in this case up. So while you are achieving positive thrust, its muted because the gas is pushing in the same direction, so your overall momentum will be reduced. If you reversed it so that the gas was pushing down and still propelling your blades at the same time, you would have much more thrust because all of your potential energy would be used in pushing the vehicle in the opposite way that the gas is pushing
I think it's because propeller blades cause more drag if you know what I mean. Wheras a CO2 cylander is so aeroodynamic and light.
So propulsion is related to the flow of mass (change in momentum, action-reaction) and the pressure of the flow (more pressure, more acceleration). The key component is the crossectional area of the gas flow. In the small gas tank, you have a lot of pressure crossing throgh a small hole. That will produce some force at the cost of high flow and less endurance. When you use the propeller you would use the tank pressure to move more air. So even though pressure is smaller your gas flow (air) increases dramatically. So you get more propulsion using less co2. Thats is why hellicopters use propellers and not rockets or even jet propulsion
But sure controlling the flow of the co2 so that it pushes the propeller is a challenge
Lightly brush the walls with solvent to seal all the holes and make the part stronger [of course, let it dry]
Delicious DeBlair yes, like paint thinner, I like this idea
I have seen some people use a small box with solvent in a vapor format where they put it into the box and watched it carefully to see when the surface got glossy then pull it out immediately.
While having a glossy surface is not totally required for an air tight seal, it will reduce air drag for a slight increase in efficiency.
If you could make a turbine impeller which is reduced to the propeller or a positive displacement gear motor [the resolution would have to be really minute, I got some brass 5 mm gears for an air motor, but without a printer can not make the housing short of milling one and that would be far too much work] you could increase the capture of the power from the cylinder, albeit you would have to be careful to not build in too much more mass to the project while increasing the power recovery.
Yours is pretty simple in comparison, but my idea was to make a propeller to drive a little airplane I made out of paper and slivers of wood.
You could also bake the print in an oven. That has been shown to substantially increase the strength of PLA prints, albeit with some warping.
pacmandrugs that’s really clever, it’d be kind of difficult to find the right temp and time in the oven so it doesn’t warp though.
Daniel Willets Hackaday did an article on this. They claim 110°C for an hour yielded a 40% increase in strength.
Well, to try an answer your question:
Opening the cartridge directly leaves you with an basic mass/ pressure driven rocket-like concept. The equation responsible is cleverly named the rocket-equation (how would have thought ;) ). It describes the acceleration as a result of the mass of the CO2 rapidly being pushed out the back. The increasing acceleration can be described as a balance between the decreasing mass of the rocket-body and the decreasing pressure within the cartridge.
The propellor version needs to overcome the rotational inertia before the rotating wings can produce uplift due to their angle and form. Further more you have to consider the drag caused by the bigger setup.
I hope this answers your question and it didn’t get lost in translation.
Love your videos! Keep doing, what ur doing.
A co2 bb gun uses a hollow needle to puncture the co2 cylinder giving it a better seal. Or look at a co2 bicycle tire inflater. They also make a self-inflating life vest, but that is a rapid discharge device. Although one model is water activated. Maybe combine that with slower discharge? Just some ideas. Great channel.
When the air is used to turn a propeller a lower pressure can be used because the force required to turn the propeller is much less than the force required to move the entire bottle. Or the propeller has a smaller mass than the bottle therefore it can be accelerated much faster to a much higher velocity than the bottle. The propeller itself is ment to displace a greater volume of air than a nozzle at the end of the bottle.
You should include a sort of spring loaded pin which perforates the CO2 canister,like the one of a pen gun,you should be able to fire it up more easily
My first thought was that the weight would be the deciding factor in terms of the resulting velocity since any propeller system would be much heavier than the CO2 rocket. If you had the same weight then the drag, friction and torque would be deciding factors. That system has more places to lose energy to friction and drag. The jet thrust from the rocket will have higher peak thrust and efficiency since it doesn't need to torque and accelerate a propeller.
That being said, if you design the propeller system differently with the spin being created with the exhaust leaving at a low pressure (showing you converted most of the potential energy from the pressure difference into kinetic energy that went to the propellers), then you'll have a much more efficient engine that can run for longer but has less peak thrust.
Even your current engine probably does some amount of throttling and can run for longer since the pressure of the air as it leaves is lower. But the pressure is still quite high as it leaves and it would be more efficient to apply that jet thrust directly to the angle of attack.
I'd say they work very well for a first prototype. Your prop design could probably use some tweaking to improve function. Altering the prop angles and shape could make a huge difference on the thrust output. I'd suggest taking a look at quadcopter prop designs.
Great video! Thank you for making it. The vehicle looks very heavy but I like the idea. Perhaps a longer duration of thrust and most of the rotors mass at the very outside edge would help the vehicle to continue flying after the C0² cartridge is finished. If that cartridge fell out or was somehow jettisoned after being exhausted the vehicle would lose a lot of weight.
In the last part of your video you can see the air escaping from the hole you made for the screw,and another thing when I observed you were outside letting them off,is they didn't go very high,whitch in my opinion the CO2 canister is heavy,I have used those to inflate my mountain bike tires.
Me and my cat enjoy your videos!
fs timelapses my cat hates the videos.
fs timelapses whatisthecatsname?
I visited McMinnville Oregon early this year to visit the fantastic aviation museum there.
One of their items is an early helicopter that used exactly this method. One of its benefits was that there
was not the torque twist that is experienced from those driven by the rotor mast.
I guess it was not entirely fit for purpose otherwise we would see them in the sky today.
Cheers from Downunder.
It would seem that the propeller design introduces more drag into the system. And doesn't use the energy as efficiently for lift when spinning vs. a straight rocket prolusion with fins/wings.
Try putting the exhaust closer to the base instead of the end of the prop. I also think an adjustable regulator will help to dial in on the proper pressure so that more energy will go into useful motion before it escapes into the environment. Good luck.
I agree. Try Exhaust down.
I think if you move the nozzels close to the shaft instead of the end of the blades you will have much better results as it will spin faster...
This is an off-the-wall idea, but if you moved those jets inboard, and then added a turbine blade outboard of the jets that was attached to a counter rotating propeller blade (rotating on a decent bearing), you would be able to make more use of the energy in the escaping air.
Aerofoil wise, a simple symmetrical blade with a shallow angle of attack would probably work best. Also limit the rate at which the gas escapes.
I would suggest that you not have it so tight against the seal. That way it has room to travel under the back pressure when the seal is broken allowing better airflow out of the cartridge.
Make the blades longer and curve the blades the same way an airplane wing is curved, it won't give as much lift as the angle of attack but the propeller having that curve will help lower the air pressure above the wing
Use a larger supply vein between the canister to the nozzles. Because rotational mass appears to be primarily inboard, move the nozzles closer inboard to achieve a higher rpm. Also, possibly try a smaller nozzle. 3x 1mm holes is a lot of flow. Step it down to half that. Velocity is your friend. Although i think your main restrictions are going to be temperature (snowing and liquid co2 freezing from expansion) and that tiny hole that the drywall screw is making. You need something like a modified wood screw that is sharpened to a razor sharp, but shallow point, so the hole is big without the screw having to go in too deep to make it.
I agree with your comment about the larger hole in the seal, that does need to happen. you can tell because sometimes the canister hardly spits out anything before it plugs the outlet. the only information that I found to remedy that told me to increase the pressure. only problem is that I cant hold much for PSI with 3D printed parts...
For low friction seal use ceramics. Like mechanical pump seal.
When using calipers, use the tapered tip to measure since that's the part that is calibrated.
Is it possible to use dry ice connected to heating element? Since solids have higher number of CO2 molecules per given volume, would it result in longer spin time for the propeller?
Would revers threads make that end cap less likely to come off? or turn the blades the other way?
As far as which propulsion system will get you further, efficiency will depend much more on how well your system is designed than one vs. the other. Imo it would be easier and better to simply design a C-D nozzle to accelerate the flow, as it has no moving parts and would be (relative to building a propeller driven system) easier to 3D print.
Makes three prototypes, buys 25 CO2 cylinders, has only one O-ring...
i am definitely going to print this thank you for including the files
Co2 is a temperature dependent gas. In cold weather the pressure can be much less. Try warming up the co2 powerlet in some warm water.
The problem is, as the pressure in the cartridge decreases, it will get colder.
Using a NACA 0006 profile with a high angle of attack and it'd be a super stable rocket and get pretty high. Or if you're shooting for duration your design with more blades but only 2 with small exit holes. Reducing the total exit size will determine how long it lasts but will also reduce the lift to the point where it might just fall immediately.
Also, even though your power delivery is within a contained area, the whole idea of for every action there is an opposite but equal action is still in effect.
I do know that the co2 bottles have enough thrust to propell larger/more wings on the propeller than you used which would give you more performance, physics wise, in a perfect world, the two methods would be equally efficient and produce the same results, maybe one having a higher speed(the bottle itself) and one having more lift force (the propeller) but in the real world there are energy losses at every point in the design, friction, heat, expansion of the gas without transfer of energy within the design, leaks, etc, this all applies to everything, cars only deliver about 8% of what they could in a perfect world to the ground
Try a reverse threaded wood screw for a .1% boost to range/height!
In principal, the propeller is more efficient, since you move more air at lower velocity, which requires less energy for the same change in momentum, because momentum is linear with velocity and energy is square. It's just a question of how efficiently the jet nozzles can turn the propeller.
But if you're keeping up with Tom Stanton, you'll know this already :)
Make a REALLY TINY hole. Make a vaporizing camera (some 0,5-1 cubic cm right after the hole). Vapor camera should have a rotatory valve at the top so in some position gas does not leak from it. Valve opens, gas makes pulse to propeller valve closes as propeller stands in the pi\2 turn.
just a humble suggestion, gentleman. add a cheap ski board bearing inside the shaft seems to be a good idea, although it may change the COG of the model and add weight but at it will turn smooth.
i don`t have a 3d printer, therefore i want to ask if it is possible to make a hollow blade where the gas can exit at the tip of the blade? check the 2000 years old greek steam engine, basiclly it is a hollow ball with 2 copper tubes curve at an angle. what if it is 2 hollow blade instead of tubes? may be you can borrow the idea from there.
Use counter clockwise threads to avoid that "not tight enough" failure
Which 3d printer and filament material do you used for printing? Thank you.
in absolute terms, the canister alone will be more efficient: it is all boiling down to F=MA the mass of the gas and how fast it comes out.
The propeller and handle will add to the mass and increase drag which will reduce efficiency.
You've heard of gear down for what now get ready for prop up for that
you know, I had to read that like 4 times to get it!
Gear Down For What? Haha lol. Thanks for replying I love your channel! I use my 3d printer to build rc aircraft! Lol
Really interesting concept.. Even do in order to acquire a larger thrust I would have make a gear reduction with a closed looped "Air motor" to move a much larger fan.. Just a thought..
The performance is likely seriously hampered by the low temperature. Do you think a narrower gas channel would help efficiency? It seems like slightly less thrust over a longer duration would reduce friction from the air and possibly make it more efficient and a narrower channel would make gas flow more laminar
I like your judicious use of time lapse.
Well the spinning propeller adds some stability and keeps rotating after the Co2 has run out, extending flight time
You should either have the cap screw on with left hand threads, or angle the props the other way. As it is the torque is trying to unscrew the cap.
That would be wise.
Gear Down For What? You need something like a convergent divergent nozzle to maximize thrust. Drilling a nozzle is probably the only way to get it right at that scale. A thin epoxy would probably seal better with less weight than silicone. If you are extra careful you can smooth pla with a temperature controlled soldering iron. And it looks like the total flow rate might be too high as it looks like you are getting a spray of liquid/solid CO2 out the nozzles, for peak efficiency you need all the CO2 exiting the nozzles as supersonic gas. Exhaust speed is a largely a function of nozzle geometry, but slowing the amount of CO2 flowing might give it a chance to warm up enough to come out as gas.
See if you can help Tom optimize his pneumatic piston engine- that thing looked really promising and adding co2 cartridges to the mix would definitely spice it up.
I think it would depend on the density of the gas being used.
I know I'm about three months late for this, but I'd imagine that a similar principle as the one behind mouse-trap cars would also apply here. Potentially.
The co2 canister on its own is more efficient, because if it wasn’t, it would violate the conservation of energy👍
Heat up the co2
There about the same you could just get a PVC tube and a nail and it will fly higher out of the "barrel"
those flat props would have been so much better had you tweacked them a tiny bit ... the crossection of the fin needs to be parabolic and also, the angle needs to be steeper near the central axel
You should put the propeller on the CO2 canister and make a launching mechanism that you can safely hold.
To optimize the thrust, creating a thrust nozzle for the tips of the exhaust might improve the efficiency. Directing the fluid (air) and chambering pressure at the release could give a completely different result. You could maybe go beyond that in rpm with a Tesla turbine.
If you haven’t fiddled with Tesla turbines, I recommend checking it out. But be careful, Tesla turbines can reach ludicrous RPMs.
What kind of 3D printer do you use I'm interested because I was looking at a bunch the other day and I don't know the first thing about them so if you don't mind enlightening me with what you use or recommend I'd be grateful thank you I love yoga videos you're a smart dude and I like every Contraption I've seen so far
it would be good if you can make a gap btw the screw and the CO2 cilinder after is pinch, so you can get a better gas flow, awesome work
In a rocket type application that would be good. In this application you you want a restricted flow. A smaller diameter piercing pin would help though.
it looks like those worked pretty well
the power of a motor (flying) is how much mass at wich speed you put out in the oposit direction of your movement
Tip jet propellers are far more efficient for lower speed if built properly, 70 lbs of thrust on the tip will fly a 2000 lb helicopter.
It's simply the pressure difference. Volume AND pressure. Great start...
it's less efective because you lose energy to heat, sound, air friction, and friction between the plastic parts.
get a 3d printed gearbox and see if you can connect it to a car and pull another car first on flat ground then maybe up hill
Propellers accelerate an airplane faster with less thrust than a jet due to the fact that they act on a larger surface of air but have a lower top speed due to lower overall thrust and limiting on rpm and prop pitch. Your propeller device would beat the plain co2 canister off the line but the canister would would pass it up if it was a longer race. Really comes down to what the use is on which is better.
And yes it's proven that a propeller can move more air then a turbine or compressed air relative to the power output or horse bower. It takes less power to move air with props.
I was expecting the propeller to spin.
I was under the impression that you were using the co-2 as the propellant..!!
about the question at 01:06 -conservation of energy is the reason why the direct thrust ist more efficient. the energy spent on spinning the propellor is lost to the creation of thrust, and that lost thrust can never be completely offset by the thrust generated by the spinning propellor (otherwise we would be able to build a Perpetuum mobile)
aednil
Don't forget the added weight of the propeller. It decreases absolute efficiency, although the design and materials of the propeller could mitigate that somewhat.
I know what you mean, and your probably right, but somehow I still want to try to argue that.
I just wish it had worked better, because CO2 Rocket Propeller is a cool idea!
@Gear Down For What? it certainly is a cool idea and you probably could make that propellor more efficient, you just can't get it to a point where you could beat direct thrust.
if it was possible to beat direct thrust with this, you could concatenate several of these propellors and have the last one drive a generator and thus you'd be able to generate any amount of energy you want, out of small, initial CO2 canister.
@WhatTheFPS well, you could try to prove me wrong by building that thing. as a bonus, you'd get very rich in the process. you could use the thrust generated by one of these propellers to drive another, slightly bigger one, and then keep concatenating that principle until you get any amount of energy that you want! good luck!
@Nouovoswiss ok, let's assume someone optimised this design to a point where the propeller produces more thrust (assuming that's possible) then it would become possible to build a Perpetuum mobile; whoever would design this thing would get a Nobel prize and get very rich. why don't you try to do it?
look, it's easy to get lost in the details of engineering and to forget basic physics principles.
If the formula I found is correct, I believe the CO2 cartridge idea is also a dead-end. The pressure in a volume filled by a 12g CO2 canister is calculated by: Pressure (psi) = 5910 / Volume (in^3). If you do the math, then a 2 liter bottle is 122 cubic inches. So, 5910 / 122 = 48.4PSI. That says each CO2 cartridge holds less energy than a 2L bottle at 50PSI. A soda bottle can easily hold 2x that much pressure, and is probably significantly lighter than the metal CO2 can. You can also splice bottles to make any volume you want.
My information comes directly from the spudfiles potato gun website. They have a nice chart showing the equivalent pressure of a 12g CO2 cart when filling standard size PVC pipes of various lengths. The closest match on the chart shows a 3" diameter pipe that is 14" in length will reach a maximum pressure of 54PSI at 70 degrees C. Your above comment states that 12 of liquid CO2 will expand to 6L of gas, which would be exactly 3 times the volume of a 2 liter bottle, meaning it would be holding 3 bar when the canister was fully discharged. If the CO2 cartridge holds more energy than a 2 liter bottle at 3 bar, then where does all the energy go when you empty it into a bottle and the bottle ends up with 3 bar of pressure in it when you're finished?
The propeller should be slightly slower because of the change of angle of the air coming out.
it's like when a circuit heats up and you lose that energy. it's the exact same thing you lose speed when you change direction The flow of the compressed air.
Plus you also lose a little bit when it's rotating think about it the rotation is still gonna go the same amount of distance but rotating counts as the distance not the height would be the sum of energy and rotation E×R= H
You should leave gaps as if there were tubes running through the propellers running to the co2 so it would make the propellers spin faster
(Sorry if that didn't make sense)
that's what i thought also, Direct the escaping air out of the tips of the propeller blades, if he wasn't already i dint really watch too closely. mostly just hung out in the comments trying to be half as clever as this chan and it's audience ;]
I used to drop Co2 cylinders down a mortar tube I made and watch them fly off
I would like to see a Propeller with a high torque, to do that, it needs your skills in designing gears.
Energy can not be created or destroyed only changed. When we change it from one state to another some energy is lost to friction, heat and so on. Here you changing thrust to mechanical then back to thrust and you are losing some energy to other factors each time.
This is more than just an idea...it actually practical. Exhausting through the blade tips can get the blade spinning without requiring counter-torque, as would normally occur with a traditional turbine design. There are real aircraft that use this...living around the American Helicopter Museum (and, hence, former Commodore/QVC, I remember it getting mentioned approximately 12 years ago on a tour. There is even a Wikipedia page.
There's also some kind of IR flare the military uses that occasionally gets reported as a "UFO" that's based on this. (Still produces some visible light.) Uses a rocket that's routed through folding blades. Unlike parachute based flares it holds a constant altitude until the rocket fuel is spent. If you look in Google's patent search you can find it under "gyro-flare" or something similar to that.
en.wikipedia.org/wiki/Rotary_Rocket
been used many times, tips go supersonic, really noisy.....
fold down prop blades would be awesome also! But could make more gas escape areas.. from what u said about prop tips having jets to release the gas, i mean if you did use folding props there would probably be a lot more issues. also, a launch/trigger mechanism that you just bang on the ground and just let go would be awesome! But the co2 would have to release insanely fast my thoughts are the co2 released after hitting on a hard surface. But i do not see it launching higher than 20 to 50 ft...idk? the power to weight ratios could be way different than im thinking.? But with tinkering and more refining of this could have many uses! Military included. Think "no more tube" morters.. just pull pin bang on rock and launch in a general direction of enemies. Have spring-loaded ones that when you pull the pin the spring causes it to snap into the co2 , pierce it and launch from a distance say With triplines or a pulled string.. Like 22 century, bouncing betty mine
. I know i went far with the military aspect of this application, my apologies! but there are so many uses for civilian life also! I like this idea ! Please Keep refining this!
The Fairy Rotodyne used tip-jets, driven by fuel & compressed-air from the main engines. It was stupidly loud, with an incredible howl from the jets! en.wikipedia.org/wiki/Fairey_Rotodyne
Jets at the tip for heavy loads. Jets in close, next to the body, for light loads.
For step angle of attack of the wing then jet at the pips. For slight angle of attack of
wings then jet in close.
I would say jet in close for better performance. Also, send the CO2 through a long narrow
pipe to warm it up. That is weather permitting.
rotational energy causes you to loose power but yours went up and didnt tumble a lot like just a rocket would unless you spent serious time designing it and the fins. also when its cold, the gas doesnt expand as much. you can see this with c02 bb guns, they underperform a lot in cold conditions. also ya your props seem a nbit heaby and they sont have an airfoil. buy some 3 inch props or maybe 5 inch props used for fpv drones and use or study thoes. they have lots of designs and there are a lot of vids for drone pilots/builders that go into the designs as when they build they want to buy the best design for there needs. also consider making it spin not from the blades as that causes turbulent air and the blades can interfere with each other if they scoop up their own air, but your not trying to hover so that may be irrelevent
This video deserves 1M views
Love the idea, does not seem as powerful as just the co2 canister, but is far more stable
It would be more efficient just to use it like a rocket because in this form a lot of the energy is going into the rotation and not as much pushing it up.
turboprops come to my mind.
Timo Schneider both are propelled by compressed gas, I didn’t even think about that
The best air motors are only around 5-10% on converting stored pressurized gas into mechanical work. Your design is very similar to the world's first steam engine. I like this project, very creative! I have printed many blades, I will post a video about some I 3d printed that are highly efficient. The files for them are on thingiverse, you may want to experiment with them, they are highly efficient for different things I have tried them for.
You could use a turbine motor from a small air driven drill
More weight, less efficiency. But generally when spreading energy over time, the propeller could help you maximize you distance traveled. If you want more power, the nail, if you want distance, the propeller. It's a trade off system, and it looks like Nuovoswiss has you covered, sorry to waste the reply lol.
cool stuff
This is an interesting design. I did a little CAD work as a result of that same video but there was a greater emphasis aero but have not printed it yet and therefore GrabCAD'ed it yet. Like many on the comments on Tom's video and similar to the one I wrote, below, you need to get the most out of your system. An interesting experiment would be to fire naked co2 cylinder, with stability fins, up into the sky. Try to record the height and do the same for the printed wings version. This may also be achieved if you know the angle on launch and measure the distance from launch, the first would be better but is more difficult. E=mass*gravity*hieght
What your measuring here is the energy expended by the co2 cylinder. You can formulate the energy of the co2 in the cylinder and using a thermodynamic table calculate the initial energy of the system. This will give you a baseline of efficiency.
The problem with the above experimental setup is that the energy will no be exhausted at the top of the so there will be potential energy + some initial energy. But, it should give a good indication of performance.
Ideally you would measure the thrust by a scale and record the thrust over time and perform the appropriate calculations. The maths is a bit more involved......
My suggestion is to 'blow the diffuser' like a Dyson.
Made this comment on Toms Video under sug15 comment was:
"On your last point on exiting the flow into the freestream: A better idea is to work the air harder. There is a large inefficiency in the system you suggested to resolve in your comment, but, the solution is to create better interactions. Usually when working with thermodynamic systems multiple stages are used to increase efficiency.
Solution: (probably need a drawing) Redesign the propellers and blow them. In a solution similar to what F1 has done, and they did a lot since the 80's, you need to create low pressure across the front surface of the prop. Just thinking the dyson does something similar with their bladeless fan. The important principle here is to accelerate the compressed gas across a curved forward facing surface that will rotate the blades. (not sure still the efficiency will be good enough for decent flight, should do the maths)
Reply to give impetus for a sketch and a link. Just like Donald Sayers says below"
Well your main issue is you use the co2 to spin the propellers by having co2 jet out of the ends of the propellers. Optimally, you'd have the co2 enter a chamber, spin a turbine connected to the propeller, then exit out the bottom of the system, adding thrust in two ways rather than just one(although I have no idea how to do that in a compact way). The reason this wastes so much energy is because most of your CO2 is being used to propell the blades in a circular motion. None of it is going towards thrust on its own. But I think it was great nonetheless
The problem with this concept is that it does not work without a second set of counter rotating blades.
if you get the propellers to spin without the base moving that would be better
Looks cool bro I do know that co2 works better in warm conditions
Do it with whip-its, and instead of a propeller, use a balloon and huff it.