DIY liquid rocket engine test fire - overexpanded flow - ONE|AEROSPACE

[@charliejaxon4707]

Wow this looks amazing! Is this pressure fed?

[@oneaerospace8022]

Yes, it's pressure fed

[@itsmewillempy]

it wil be nice to show your complete setup or schematic of your setup. very awesome

[@oneaerospace8022]

Thank you. We will do a video giving a more detailed look on the engine assembly and test stand in the near future.

[@itsmewillempy]

​@@oneaerospace8022 Thanks you very much

[@snaaail]

That's so cool, how do you make your nozzle?

[@oneaerospace8022]

Thank you! In this prototype version we use a simple plug that is screwed into the combustion chamber tube. The converging part of the nozzle is made using a countersink and the diverging part using a drill bit that has the shape of the nozzle contour. However, this is only possible for very small nozzle ratios.

[@snaaail]

@@oneaerospace8022 Thanks for the response! Are you able to share what the nozzle ratio is? Is this ratio something you adjust to prevent flow separation and maximize thrust?

[@oneaerospace8022]

Sorry for the late reply. Ratio at the moment is only 1.6. Yes, we constantly adjust the ratio depending on the chamber pressure to prevent flow separation in the nozzle exit area. We also test different ratios for maximum thrust determination

[@snaaail]

@@oneaerospace8022 That’s so cool, thanks. Hopefully one day I can work on a rocket engine, cool stuff!

[@Marcus_Sherman]

What’s the engines Specific impulse? I love home made rocketry and im excited to see more of your content

[@oneaerospace8022]

We have reached an Isp of 144s so far. We hope to increase it with our second engine that has an updated nozzle and combustion chamber to stand higher pressures and reach higher exhaust velocities. Testing will begin in the coming weeks so stay tuned!

[@stocky9218]

Awesome

[@oneaerospace8022]

Thank you!

[@yoyococo9657]

Nice job!!

[@oneaerospace8022]

Thank you!

[@torion7704]

Sehr gut

[@oneaerospace8022]

Danke!

[@adammosonyi4671]

Great work

[@oneaerospace8022]

Thank you!

[@resto-dw7gv]

You also got some mach diamonds💯

[@oneaerospace8022]

Yes! The nozzle seems to be working as expected

[@resto-dw7gv]

@@oneaerospace8022 that is good. Btw how much you paid for the entire project?

[@oneaerospace8022]

@@resto-dw7gv Very hard to tell, probably 2500 to 3000 € in material but as we build almost all parts on our own there is countless hours of planning, designing, manufacturing and testing in multiple iterations that have to be considered aswell!

[@resto-dw7gv]

@@oneaerospace8022Incredible work

[@AbstractBinaryOfficial]

I would love to help you with this, as it seems you have some obstructions within the combustion chamber, causing your exhaust to be flat on one side.

[@oneaerospace8022]

Thank you, help is always appreciated! Well, we inspect the combustion chamber before and after every test but we did not find any sort of obstruction after that test. However, the diverging nozzle we added before this test was just a very quick and dirty solution not using our lathe but a regular drill press instead. This causes many problems such as the diverging part of the nozzle not beeing fully centered to the nozzle throat. This might also be the reason for the deformation of the exhaust.

[@tristanlongangue5671]

What is your tank pressure?

[@oneaerospace8022]

7.2 bar for this test. We will increase it to ~10 bar depending on the maximum oxygen flow we can achieve to improve both chamber pressure and thrust. Max design pressure for the fuel side is ~12 bar.

[@ukdrilllyrics2624]

Where did u get the fuel for it?

[@oneaerospace8022]

Ethyl alcohol is from the next supermarket and the oxygen from our local hardware store.

[@ukdrilllyrics2624]

@@oneaerospace8022 what drinks can the ethyl alcohol be found in?

[@govindchari4586]

How do you cool your nozzle and combustion chamber?

[@oneaerospace8022]

At the moment we don´t use any sort of active cooling for simplicity reasons. So just radiation and convection cooling of the outer engine surface. However, the geometry concentrates a lot of material in the nozzle region to function as a heat sink as the highest heat flux can be expected here. So currently the engine supports tests of up to 10 seconds.

[@JeffreyZhuang]

What is that white glue you used?

[@oneaerospace8022]

It is a special assembly paste for exhaust pipes. It can stand high temperatures and expands when heated up

[@JeffreyZhuang]

@@oneaerospace8022 Do you have it's name?

[@oneaerospace8022]

Sorry for the late reply, sometimes we miss the notification for a new comment. It’s called “firegum” by holts.

[@jurajkolesar1894]

doing a similar project ---> SUBSCRIBED

[@oneaerospace8022]

Nice, what thrust-range are you aming for?

[@jurajkolesar1894]

@@oneaerospace8022 it is planmed to be around a KN of thrust with a Isp of 280s running on kerosine and gox. It will be the biggest project in my life. Well only if it does work :DD

[@oneaerospace8022]

Wow a kN is quite ambitious! What oxygen-mass-flow is needed?

[@jurajkolesar1894]

@@oneaerospace8022 enormous about 300grams a second that will be really scary

[@jurajkolesar1894]

Dude and I want to tell you this project of yours is really amazing

[@VortrexAerospace]

You could do a tutorial on how to make an engine like yours, I am really interested in creating my own engine. PS: YOUR ENGINE IS FUCKING AMAZING, keep it up, Greetings from Mexico bro :)

[@mmb3006]

may i ask what sort of injector did you use?

[@oneaerospace8022]

We use a coaxial swirl injector.

[@mmb3006]

@@oneaerospace8022 wow that's impressive do you know your combustion efficiency?

[@oneaerospace8022]

We currently have an overall engine efficiency of about 90%. We assume the combustion efficiency to be in the range of 95% as the calcualted values for mass flow rates, O/F and chamber pressure for this efficiency correspond to the values observed during testing.

[@mmb3006]

@@oneaerospace8022 wow that is insanely efficient 😳

[@oneaerospace8022]

It is. We put a hugh amount of work into the injector to allow for sufficient combustion. We performed lots of tests to reach a good atomization and spray pattern of the fuel and to find the right recess-length for pre-mixing of the propellants inside the injector. Thus, we are able to almost use the whole combustion chamber length for combustion. However, GOx simplifies things a lot as it does not have to be atomized and can be mixed with the ethanol easily. We also use a fairly long combustion chamber which gives the fuels a lot of time to react.

[@oneaerospace470]

Nice

[@oneaerospace8022]

Thank you!

[@jeremymcadam7400]

Give yourself a pat on the back lmao