Liquid rocket dev.

[RoadRunnerAerospace]

Long story as to how I wanted to make this, so I wont get into it here.... But its a thing! I have started sketching this thing out!

Its meant to use either gasoline or 90% alcohol, using the outside air as its oxidizer until I can get access of liquid o2  (long time). I`m currently doing a very quick sketch, using just a few "rules of rocket design", its going to be water cooled using some very small pipes, the injector pipe is going to be kinda crimped for lack of better words, to add pressure.

[sevenperforce]

2 hours ago, RoadRunnerAerospace said:

Its meant to use either gasoline or 90% alcohol, using the outside air as its oxidizer...

Do you mean to pump in compressed air? I would look at NO2 or H2O2 if I were you.

How are you going to pump in the fuel?

[Steel]

2 hours ago, sevenperforce said:

Do you mean to pump in compressed air? I would look at NO2 or H2O2 if I were you.

How are you going to pump in the fuel?

If you plan to use air (probably not the best plan, since its only 21% oxygen) you'd need a compressor set up to actually get the required flow rate into the chamber.

Gaseous oxygen is not too hard to get hold of, and would serve the purposes of a rocket engine far better. Also, there are existing examples of people who have done DIY GOX rockets to help you along.

 

Also, if you haven't seen this thread, I'd highly recommend checking it out, it's pretty extensive on calculations and such. 

 

Edited September 21, 2017 by Steel

[Racescort666]

3 hours ago, sevenperforce said:

Do you mean to pump in compressed air? I would look at NO2 or H2O2 if I were you.

How are you going to pump in the fuel?

Do you mean nitrogen dioxide (NO2) or nitrous oxide (N2O)? Nitrous oxide is common as an oxidizer while nitrogen dioxide is usually considered a pollutant but is also present in RFNA. 

[sevenperforce]

35 minutes ago, Racescort666 said:

Do you mean nitrogen dioxide (NO2) or nitrous oxide (N2O)? Nitrous oxide is common as an oxidizer while nitrogen dioxide is usually considered a pollutant but is also present in RFNA. 

Oops, meant nitrous oxide. Stupid me.

[Ultimate Steve]

This is a bit off topic, but I would like to ask a question.

Where are you living that this is legal? Because I'd really build stuff like this if it was somewhat legal... In particular I've been considering a monopropellant rocket for quite some time.

[RoadRunnerAerospace]

I live in maryland, and i`m not completely sure that its legal to test it in my backyard, I may have to go to a bomb range and test it

 

 

Oxidizer is being worked out.....

 

 

Edited September 21, 2017 by RoadRunnerAerospace

[RoadRunnerAerospace]

Engine blend done!

Wow, this thread really took off too!

 

[Steel]

4 hours ago, RoadRunnerAerospace said:

Engine blend done!

Wow, this thread really took off too!

 

Have you done the calculations to get the throat area, chamber volume e.t.c to roughly the correct size?

[RoadRunnerAerospace]

yes I have!

[RoadRunnerAerospace]

Injector design is done! Oxidizer is gaseous o2

[totalitor]

What is throat area? It seems that exit area is too large. For example 100 psi chamber pressure exit area should be about 2*throat area on sea level (info from book How to design small rocket engines). Of course if you have super large chamber pressure and vacuum optimized engine that is what it should look like. But I think you start from scratch like I do.

[RoadRunnerAerospace]

I probably messed up some of the math..... Yay! Time to check ze math!

Any ideas as to attaching a ceramic nozzle to a ceramic combustion chamber?

 

[sevenperforce]

19 minutes ago, RoadRunnerAerospace said:

Any ideas as to attaching a ceramic nozzle to a ceramic combustion chamber?

Very, very carefully.

Duct tape is probably out.

Honestly, though, I would look into a tongue-and-groove arrangement (where the edge of the nozzle slides into the combustion chamber) with retaining/tensioning bolts on the outside. Probably the simplest, most reliable way of doing it. 

[RoadRunnerAerospace]

hmmm.... T`would require an O ring

[RoadRunnerAerospace]

About a quarter through re-doing my math... Of the nozzle (whee!).... turns out I misread the page that I used, got confused, and yeah....

 

 

Edited September 22, 2017 by RoadRunnerAerospace

[RoadRunnerAerospace]

What I know right now (math still in progress)

-goes through 5.344g of fuel a sec

-goes through 13.3844g of oxy a sec

-300 psi chamber pressure

-10lbs of thrust (not expected)

-isp of 242

-Gox and Gasoline

 

[NSEP]

On 24/09/2017 at 4:02 PM, RoadRunnerAerospace said:

-isp of 242

(no political meaning or intentions intended)

 

[sevenperforce]

Suggested geometry for attaching the ceramic nozzle to the ceramic combustion chamber:

So you have an O-ring, yes, but it is protected from direct exhaust impingement by the tongue-in-groove. You can attach and detach using bolts around the perimeter of the flange connecting the chamber to the nozzle.

 

[RoadRunnerAerospace]

Thats actually very useful! thank you!

[lajoswinkler]

Why ceramics?

Why not graphite? It's easier to machine in one piece and very inert. One way or another, you always have to put extra reducers, whether it's kerosene, hydrogen or whatever, so you have a reducing atmosphere that won't eat the material.

Edited September 26, 2017 by lajoswinkler

[RoadRunnerAerospace]

I have it lying around, and I can shape it without any special equipment