O2 + H2 rocket

[Grawp]

Would it be possible to build H2 + O2 rocket using plastic bottles as storage for pressurized gases?
I've been playing with this idea for a while now. It wouldn't be a problem to fill the bottles with the gases, although I don't even roughly know how many atm could ordinary plastic bottle handle..
I can obtain high-pressure electronic valves, make the outer shell, use servomotors for controlling fins or for thrust vectoring. Maybe I could even implement AHRS with some cheap gyros......etc.. This all bring me to the main problem: I have absolutely no idea how to make the actual engine .. combustion chamber + nozzle or if it is even possible and efficient. What do you think?

(sry for my english)

 

[RisingFury]

You wanna blow your house up or what?

 

[Urwumpe]

I think the thrust to weight will be very unfavorable. Especially since hydrogen has very low density.

 

[RisingFury]

 

[Grawp]

I think the thrust to weight will be very unfavorable. Especially since hydrogen has very low density.

Hydrogen can be replaced by kerosene.. leaving more room for oxygen.

YouTube - Creating Hell in a Pop Bottle

I know this very well. I blew up 10L plastic can once (filled with O2 and few ml of kerosene). Pretty loud bang...

 

[Urwumpe]

Hydrogen can be replaced by kerosene.. leaving more room for oxygen.

It is not about room, it is about how much "machinery" you need to turn the fuel into thrust. With pressure feed from plastic bottles, you won't get enough pressure to reach the same high specific impulses as large rocket engines. And getting the fuel mixed and burned effectively is another problem at small scales. Or making sure that the exhaust does not cool down too fast while expanding.

Also, for making use of aerodynamic stabilization, like other small rockets, you need about 5 g acceleration, so every kilogram of rocket has to produce 50N thrust. You need to get about 4 grams of gaseous oxygen into the combustion chamber every second for every kilogram of rocket. Below 10 kg rocket mass, it will be hard even getting the plumbing into the air - even a small RCS thruster already weights a kg.

 

[RisingFury]

It would be far easier making a H2 + O2 cannon...

 

[Urwumpe]

It would be far easier making a H2 + O2 cannon...

And then much easier turn this cannon into a light gas gun.

 

[Grawp]

It is not about room, it is about how much "machinery" you need to turn the fuel into thrust. With pressure feed from plastic bottles, you won't get enough pressure to reach the same high specific impulses as large rocket engines. And getting the fuel mixed and burned effectively is another problem at small scales. Or making sure that the exhaust does not cool down too fast while expanding.

Also, for making use of aerodynamic stabilization, like other small rockets, you need about 5 g acceleration, so every kilogram of rocket has to produce 50N thrust. You need to get about 4 grams of gaseous oxygen into the combustion chamber every second for every kilogram of rocket. Below 10 kg rocket mass, it will be hard even getting the plumbing into the air - even a small RCS thruster already weights a kg.

And using your value of 4g/s * 5kg, for 20s burn with 20L gas container.. the cont. has to withstand 30 atm. And with ~50atm rated container the rocket will weigh more than 5kg, not including other things... I know. But who says it have to be small rocket? :lol:

Anyway, it would be interesting to build such engine even only for ground experiments. With 1kW electrolyser I can feed some small engine directly. I've already built torch from it. Now I want to upgrade the torch with combustion chamber and nozzle. Could you point me to some website concerning detailed rocket engine construction?

(About safety concerns .. I'm crazy, but not a fool... at least most of the time.)

It would be far easier making a H2 + O2 cannon...

I know. But i'm over making cannons. Not funny any more..

 

[Ghostrider]

And then much easier turn this cannon into a light gas gun.

And then use the gun to force someone to hand over a proper engine.

 

[Grawp]

lol

 

[Wishbone]

Oxygen is very dangerous (all pressurised gases are, but O2 is worse) (I suppose you'd attempt to get it from a welding shop). The best place for propulsion experiments is a university lab, under supervision of those who have already done that without going through the roof.

 

[RisingFury]

And using your value of 4g/s * 5kg, for 20s burn with 20L gas container.. the cont. has to withstand 30 atm. And with ~50atm rated container the rocket will weigh more than 5kg, not including other things... I know. But who says it have to be small rocket? :lol:

A very creative way of commiting suicide, I must admit...

 

[Grawp]

Oxygen is very dangerous (all pressurised gases are, but O2 is worse) (I suppose you'd attempt to get it from a welding shop). The best place for propulsion experiments is a university lab, under supervision of those who have already done that without going through the roof.

I'm obtaining O2 from electrolyser. I'm using H2SO4 with water and tens of amperes (12V). I know what O2 is! And how dangerous it is, especially directly mixed with H2. I've already blown one elektroyzer on purpose as danger assessment test, so I practically know what I'm dealing with, not only theoretically.