Devlog 02 Tranga Rocket Engine

What I’ve Done So Far

So since the last devlog I’ve done a few things, first I 3d printed the Injection plate and tested the screw fits which worked. Then I went in and did some final fixing up before modeling the combustion chamber and nozzle component.

My Thoughts On A Future Component

One of the next section I need to design in the parts that will intake fuel and oxidizer from the flow lines and inject them into the injection plate, I’m quite concerned about how air tight this component will be and I’ve thought of two main options.

1. I have a ring shaped pipe that has in input for 1/4 inch pipe and little outflows feeding into each injection hole, where this piece meets the injection ports we’ll have tiny rubber O-rings to seal. I’m a bit concerned about the extra machining involved in this part in terms of cost, and I feel that the fuel may flow through some section of the injection plate more than others.
2. We have tiny feed lines the screw into ports on the injection plate and all meet at 1/4 inch pipe junction, with this approach I feel like I might be able to find an off the shelf part but if I can’t this piece would require far too much machining to be worth it.

A bit of crowd sourcing

If anyone knows where I can get solenoid valves and a pressure sensor rated to handle air at 1mpa that would be a big help, I’m new to working with hydraulics or pneumatics or whatever you would call it so I don’t really know what A good price is, I have to pick out the parts during the design phase so that I can design the engine around them. If anyone knows any good options that would be a big help.

Devlog 01 Tranga Rocket Engine

This is my first devlog for my Tranga rocket engine. I’ve called it Tranga based off my choice of propellants, pressurized air as the oxidizer and methylated spirits as the fuel, which is the same as a Tranga outdoor cooking set. Most people would probably make a solid propellant rocket motor first but solid propellants are illegal here in Ireland so we’re jumping straight to pressure-fed.

Basic Design

So the basic design, we’ll have our methylated spirits and pressurized air in aluminium water bottles and the pressurized air will also double as ullage gas to push the methylated spirits into the system. This design will take a lot of evaluation in the design phase, such as ensuring the safety of using the oxidizer for ullage.

Injector plate Design

So far the injector plate has six holes for M6 screws to tightly secure it to the combustion chamber, with 16 2mm holes for fuel and 6 0.2 mm holes for oxidizer, this creates a 7:1 fuel rich mix ratio, I’ll likely modify this down the line but this reduces the temperatures experienced internally. Once the engine is done I have a plan to add regenerative cooling to increase burn time and change the mix ratio.

More Detailed AI Disclosure

The core purpose for which I used Claude is that it seems to have some internal access to NASA Computational Fluid Dynamics tools for responding to requests, It would be a complicated process for me to gain access to these tools and learn to use them, using Claude to run these simulations will most likely result in reduced accuracy and lower performance but I’ve decided it’s acceptable for a minimum viable product. So Claude generated the sizing for the injector plate, combustion chamber, and nozzle but I’ll be modelling them myself based off of these measurements.

Safety Disclosure

Obviously in designing this safety has to be a massive consideration, I’ll explain my methodology deeper in future Devlogs but I feel it’s important to notes that I have the privilege of being able to test the engine where it will be far from people. I also only intend to do short burns as this engine most likely won’t be much more than an over-engineered flame thrower.
I couldn’t find anything on the stardance website about what hardware projects are and aren’t allowed but I would completely understand if this is considered too dangerous.