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Air Powered Piston Engine

#1
On the unofficial FliteTest discord, we have been chatting about the Skyshark from AirHogs and the air-pressure powered piston engine it used.


This design is really cool, but sadly these old planes have become a relic of the past, and very hard to find.

However, with 3D printing being so common and inexpensive I would personally love to see FliteTest take a crack at making a 3D-printed air-piston motor that could could use a small water bottle or a 1 liter soda bottle for the pressure chamber. For added fun, you could also try doing things like using dry-ice and hot-water as a "fuel" source.

I don't think you will have to do entirely an new design as someone also mentioned this prior art:

Maybe he would work with you all too.

Happy Flying!
 

Tench745

Well-known member
#2
I had that purple Air Hogs plane, and after I finally broke both the wing and the replacement wing I got the next newer model and broke that too (I believe it was red and grey). I always wanted to rebuild it and reuse the motor etc, but by that time the pump was broken and the seals in the motor were wearing down. Still, I wish I'd never gotten rid of it. Knowing what I know know it would be a simple fix.
 

Tench745

Well-known member
#8
What if you used a 20g Co2 cartridge? Those things go up to about 900 psi!
You definitely would need some sort of limiter...
I've got a couple 25-38 gram cylinders from old life jackets I'd be happy to send you except that the postal service won't take 'em.

As I understand it, CO2 powered free flight aircraft were a thing for quite a while before glow power started to take off.
 

"Corpse"

Well-known member
#11
Sure, but how many FliteTest videos fall in the category of "practical?" I think that is often the point though, to inspire people to try something new and different and learn from it along the way.
So true! And to make a practical tool you have to start with something kinda strange. I mean, was the Wright brothers plane practical?
 

"Corpse"

Well-known member
#12
I've got a couple 25-38 gram cylinders from old life jackets I'd be happy to send you except that the postal service won't take 'em.

As I understand it, CO2 powered free flight aircraft were a thing for quite a while before glow power started to take off.
Thanks, I can get some 20g cartriges at walmart for 4 bucks. No big deal. Now only if I can convince @The Cookie to 3d print the engine. :ROFLMAO:
 

Piotrsko

Well-known member
#13
Iirc, the C02 engines were like Cox .020 with a air line instead of the glow plug, no valving just exhausting at the bottom of stroke. Regulation was done by orifice diameter, fine tuning by needle valve. I make no guarantee remembering accuracy after 50 years. @quorneng probably has a working one. ( wouldn't be suprised)
 
#15
I found another proof of concept turboprop on youtube which operates on similar principals.


This concept appears to be a lot simpler to design. However, things always tend to appear much easier than they actually are. For example, it is not clear in the video how much PSI or CFM was used or required to spin the propeller the demonstrated speeds. I suspect it is a lot more than a small CO2 cartridge can provide. Still pretty nifty.
 

Piotrsko

Well-known member
#16
Well, back in the day: the ones I saw probably didn't run more than 2-3 minutes since they were on free flight planes and more than that caused the plane to generally fly away. Saw them on some indoor C/L too. They were operated on seltzer bottle cartridges much like the C02 ones today. Lotta help there. Someone made them before 2000 since there was a resurgence in old tyme planes back then, but like everything else, died in the after recession. I haven't seen them since.