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🚀CO2 Powered... Propeller? Rocket?
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- Опубликовано: 14 янв 2018
- Propeller: www.thingivers...
Tom's Video: • Air Powered... Propeller?
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For low friction seal use ceramics. Like mechanical pump seal.
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.
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.
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.
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.
You could use a turbine motor from a small air driven drill
To simplify things without using big words so others won't understand I think that when you break the seal its forcing the canister downwards. Every force has a equal or opposite reaction. And that's why it doesnt fly too far because it's forcing the c02 down
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
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.
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.
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
There about the same you could just get a PVC tube and a nail and it will fly higher out of the "barrel"
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
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
You should put the propeller on the CO2 canister and make a launching mechanism that you can safely hold.
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.
it looks like those worked pretty well
The co2 canister on its own is more efficient, because if it wasn’t, it would violate the conservation of energy👍
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.
if you get the propellers to spin without the base moving that would be better
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.
Remember the music from an old aircraft game
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.
Do it with whip-its, and instead of a propeller, use a balloon and huff it.
I would like to see a Propeller with a high torque, to do that, it needs your skills in designing gears.
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.
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.
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...
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
it's less efective because you lose energy to heat, sound, air friction, and friction between the plastic parts.
I think it would depend on the density of the gas being used.
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.
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 :)
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.
dont do it in the cold the warmer the better for co2
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
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.
It's much more stable, that's for sure.
Check out the NACA Number registry. It will give you a great baseline for airfoil shapes.
I think this is an analogous difference between a jet and turbofan - turbofan is more efficient...
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
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.
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.
You should try making a gyrojet ammo..
Pretty good reaction for being so cold 🥶
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
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.
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.
A rocket is inherently unstable and needs fins to keep straight, whereas the vehicle should be hanging from a proper (like a helicopter) and its own mass keeps it upright.
the power of a motor (flying) is how much mass at wich speed you put out in the oposit direction of your movement
Looks cool bro I do know that co2 works better in warm conditions
You need heat, and you need a device that will extract the heat. I am doing this on my channel, a Tesla turbine would be your best result, you can use ambient air to heat your gas through a heat exchange. This would massively increase the output of the device.
Use much shorter blades. The smaller the blade the faster it can turn. Other then that your concept is good.
Doraemon's Take-copter..?
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.
what if the military upgrade this thing
Interesting.
Why not make it remote controlled have something open for he cartridge from a control
Why not print it thinner and line it with carbon fiber and epoxy? Probably too heavy right?
Look up the original Air Hog Plane
Using Propellers you should have more gyroscopic stability, so it will less wiggle in the air.
i wonder if it'd be possible to make a 3d printed co2 piston powered propeller
Tom stanton make something similar with compressed air
Try taking up RC planes flyimg FPV, can use bigger cameras with better video quality. FPV puts you in the plane when flying, can also fly to the particular areas of interest for videoing. I have several videos on my YT page as examples.
More aggressive rake/ angle on the leading edge of the propeller?
You damn aggressive rakists, always being edgy just trying to lead and propel ur angle more!
You ask which one is more "efficient": the CO2 canister alone, or with the prop? I say neither of them. :) The third option is the winner.
First, what do you mean by "more efficient"? Do you want more thrust (acceleration) or do you want it to go higher?
- Releasing the CO2 quickly gives you more thrust, but for a very short time period.
- Slowing down the CO2 means lower thrust, but over a longer period of time - might fly higher.
Let's say you want to go higher!
- Why blowing out the CO2 directly is a bad idea: As others have stated in the comments, when the CO2 leaves the canister with a very high speed, it takes with it a lot of kinetic energy. It doesn't stop in mid-air after coming out of the canister, it goes on and that energy is lost. Now, if you can slow down the CO2, then less energy gets lost, and on top of that - again others have mentioned this - because the expanding CO2 cools down the canister and the gas, if you do it more slowly, it allows the canister+gas to absorb heat from the environment which adds more pressure.
Your propeller device has the good idea of slowing down the gas by pushing it through a small hole, but turning the hole thing and ejecting the gas sideways is a waste of energy.
If you twisted (change the pitch) the propeller blades so the blowing holes on the tips pointed downward, you would get the benefit from slowing down the gas, but it would not waste energy on turning the whole thing. Then you can remove the blades and what you get is a rocket!
Now what I'm gonna do is go ahead and do what I'm gonna do
Hello man. Why do not you try to build it with canard design, I think the co2 tube pushes down?
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.
Add a camera to it?
maybe?
no?
ok.
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?
Makes three prototypes, buys 25 CO2 cylinders, has only one O-ring...
Let's see it fly, where are your launch clips ?
In the video! You must of missed them
Bravo........maybe nitrous whip it ......and build micro rocket engines on tip of wings.......three forms of motion forms of motion.....gas that escape thrust....and if it is in a Cylinder then u get expansion wave...... and then u can ingnation fire power wave.....
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
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.
Good video, good job...
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.
Plz make a plane or helicopter
Where did you get that Lutron screw driver
My brother actually
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.
Well the spinning propeller adds some stability and keeps rotating after the Co2 has run out, extending flight time
Try a reverse threaded wood screw for a .1% boost to range/height!
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.
Where does this genius live? -20 C or F is kinda cold AF but even indoors one should wear gloves working with and esp. quick releasing compressed gases... I would not use a drywall screw for puncturing tho, maybe a thick, at least
😀😀😀
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.
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.
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.
When using calipers, use the tapered tip to measure since that's the part that is calibrated.
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?
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...
Physics time😂, simply using the cartridge as a rocket is more efficient in terms of forward velocity as your propeller design redirects some of the gas flow and has some leaks. Essentially your design uses thrust that was in the desired direction anyway and converts it into rotational motion which is then converted into thrust by displacing air and generating lift. The interesting idea would be to create some form of aircraft which slowly released the co2 which would improve efficiency as it would reduce the impact of evaporative cooling on the cylinder. The propeller design is however inherently more stable. An easy way of thinking about it is, if you ignore evaporative cooling, simply dumping the mass of co2 at high speed is more efficient than converting that into rotational motion and using that to shift a load of air as that introduces inherent inefficiencies. Thrust generated by the lift of the aerofoil on the prop wings is an interesting concept to consider, if we say that the purpose of the design was to slow the release of gas and hence increase efficiency. Then I'm not entirely sure how the efficiency of this would compare to a straight rocket. I'd actually be quite interested to compare these as it's a sound concept. Awesome design work btw!
Is there a video where you let it fly outdoors?
Yeah, this one. You skipped that part
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..
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!
What program u use to make those things
i am definitely going to print this thank you for including the files
i guess youve never heard of Air hogs
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.