/diy/ - Do It Yourself

>>851450
Difficult. You need strong pumps (complex) or just high pressured gas since you have to get the fuel and the oxidizer into the burning chamber, which is also high pressured. This is what this sphere tanks are for .

Search the internet for:

Sutton & Biblarz, Rocket Propulsion elements. Its available as a pdf...

also https://www.risacher.org/rocket/ from the rocket lab on china lake

>>851488
This. Also, find Humble and co's "Spacecraft propulsion analysis and design".

OP, for a small model, you want simplicity. So the engine will have to be pressure fed.

For a small liquid motor at sea level, you'll end up with quite a big tube shaped combustion chamber compared to a relatively small nozzle. You can use an aluminum or steel (depending on whether you want it lightweight for flight or not) tube for the chamber casing. An inner tube of an ablative material will be required for cooling. Phenolic formaldehyde impregnated cotton or paper works well, in the UK we call them Tufnol tubes. The nozzle can be graphite turned on a lathe.

The trickiest part here is the oxidizer. I don't know how you can get liquid oxygen in small quantities as it usually comes in a dewar (big thermos flask). For this reason, you might be better off using N2O, nitrous oxide, as it's available in smaller quantities for motorsport.

Nitrous is also self pressurizing, so you'd only need to pressurize the fuel, which is nice. The flame temperature will be a bit lower than liquid oxygen, which means you can reuse your nozzles as the 'throat' (narrowest point) will erode less.

Read well, but whatever you do, it will probably explode first time, as is the nature of rocketry. Instrument it well (try to record chamber pressure) and iterate.

Do you want full liquid or hybrid can do?
https://metalab.at/wiki/Salami_Rocket

>>852494
>how you can get liquid oxygen in small quantities
They sell these little babies for handful of EUR:
https://www.drainagesuperstore.co.uk/product/providus-spare-oxygen-for-use-with-providus-lead-welding-kit.html

>>851450
>Does anyone have any knowledge in how to construct a small model of these?

Well, it's not exactly brain surgery is it?

One of the easiest fuels to get your (gloved) hands on is HTP ( High Test Peroxide ). Relatively easy to manufacture yourself, but I'd recommend keeping any organic materials AS FAR AWAY from it as possible. Good luck!

>>852881
Which is harder? Brain surgery or rocket science?

>>854244
? Did you even read the fucking thread? Ok, then go build a stable liquid fuel rocket engine that is self sufficient to cool itself, then go post a retarded comment like you did. "It's not exactly brain surgery is it?" Fucking moron

>>854244
Rocket surgery is way harder than either.

>>854378
Got jewed out of your Viagra again, pops?

>>854378
I think you quoted the wrong post buddy.

>>854378
https://www.youtube.com/watch?v=THNPmhBl-8I

Hmmm, well i was thinking of running the fuel mixture through a series of double walls to cool the engine before it eventually running through the injector, and being burned. Similar to the V-2 engine. However i dont need one that has 150,000 lbs of thrust, just a smaller one to launch a 100lb rocket. Id rather not use cryo fuels since they are hard to handle and transpor. Id rather use peroxide and something else. since peroxide can be store like gasoline, not needing very special containers. not to special a least.

>>851450
You could make an easy thruster using concentrated hydrogen peroxide and a ceramic catalyst, put the thing in a nozzle then fire away !

>>851450
I'd recommend a hydrogen peroxide based design. They demand the fewest parts and only one reactant (so no worries about optimal mixing).