Hybrid Rocket Engine Combines Ceramic Aerospike With 3D Printed Fuel | Hackaday

2022-05-09 08:04:12 By : Ms. Lavy Luo

[Integza] has worked hard over the last year, crafting a variety of types of rocket and jet engine, primarily using 3D printed parts. Due to the weaknesses of plastic, all of which conflict with the general material requirements for an engine that gets hot, he has had less thrust and more meltdowns than he would have liked. Undeterred, he presses on, now with a hybrid rocket aerospike design. The goal? Actually generating some thrust for once!

The latest project makes the most of what [Integza] has learned. The aerospike nozzle is 3D printed, but out of a special thick ceramic-loaded resin, using a Bison 1000 DLP printer. This allowed [Integza] to print thicker ceramic parts which shrunk less when placed in a kiln, thus negating the cracking experienced with his earlier work. The new nozzle is paired with a steel rocket casing to help contain combustion gases, and the rocket fuel is 3D printed ASA plastic. 3D printing the fuel is particularly cool, as it allows for easy experimentation with grain shape to tune thrust profiles.

With the oxygen pumping, the new design produces some thrust, though [Integza] is yet to instrument the test platform to actually measure results. While the nozzles are still failing over a short period of time, the test burns were far less explosive – and far more propulsive – than his previous efforts. We look forward to further development, and hope [Integza’s] designs one day soar high into the sky. Video after the break.

Was not expecting a diversion into the tomato death squad! Glad someone is having fun :)

I’m glad he’s moved out of his attic — as, I am sure, is his insurance company!

IKR? Safety is definitely NOT his middle name.

As always he builds neat stuff. But I do not understand why he prints the flange to mount the nozzle, I thing he should weld it and make it from metal. Also the cap for the hose seem to complicated, I think he should just weld a round plate to the end of the pipe and also weld a insert from steel for the hose into it. I thing that would be simpler and more temperature resistant.

Btw. as far as I have learned from the Mythbusters the oxygen should enter the chamber in liquid form, but that could result in a dangerous amount of trust.

I’m glad that I am not the only one who noticed the nozzle bolted to the fuel grain, rather than a flange welded to the steel rocket body. My guess is that steel would also be more heat resistant than the ceramic Integza is printing in and make for a better nozzle

Things start to get more dangerous as you make them stronger.

Definitively, its probably already time for a bulletproof shelter.

He’s a good experimental engineer, but maybe he isn’t good at welding.

he is absolutely not good at welding, by his own statements. he got a small welder just for this project. trying to weld a flange onto the barrel without it warping would have even more problems than the printed-with-grain flange

There is no need for it to be liquid, and infact that could end up producing less thrust, or even no thrust if you dump too much in – you just need to introduce enough oxygen to continuously completely burn the exposed part of the fuel grain, any extra is mostly wasted (except for some minor aid it can provide carrying away the burnt up and sooty bits, and as extra reaction mass which will up thrust some), so he probably could use higher pressure or liquid judging by the rather poor looking results.

But with the other challenges he still has to overcome making it survive I don’t think its the next area to work on.

> but that could result in a dangerous amount of trust.

Not sure about the metal either, but if in the next iteration you make a metal flange welded to the metal tube, you can screw the ceramic nozzle onto it. Then you would just insert the plastic fuel cartridges into the rocket. If you got a little fancy, you could have a metal ring or cap with a dimple in it to hold the ceramic nozzle instead of just the 6 bolts.

I also got to thinking that if you are doing all this work with steel, you might also consider just using steel and cast iron plumbing pipe and fittings. For some inspiration google how blacksmiths make venturi burners out plumbing parts. For yours you would likely want a cap with a threaded hole for the oxygen fitting.

Spent some time making jet engines. There is a common design used in the “hot” section. I don’t know if you can pull this off, but cooling channels down the length of the ceramic keeps it’s temp way down. The air is “sucked” through the cooling channels by effects of the exhaust.

a cooling eductor sounds like a headache to print without warpage

From what he has shown of that resin I don’t think it would be that bad to print actually – it keeps the walls thin (which seems to be perhaps the most important part), while adding structure that will stiffen the cone, and can be part of helping keep the geometry stable as its cooked.

I think you could do a simple chemistry test to find out what kind of metal you’re getting there. A magnet would tell you if it’s steel. (I know, that’s not chemistry) Chemistry test could verify your aluminum hypothesis.

Is it possible that the metal residue is because he’s running pure oxygen? Could it be that the metal is oxidizing and burning as well? I’m just curious.

Its absolutely possible, you can even just with pure oxygen flow to keep cutting metal (does require getting it really really damn hot first (so oxy-x-torch), but once you are there just the oxidising of the metal is enough to keep that temp up so you can keep doing it without whichever fuel gas got it started), though I don’t think he is really getting hot enough near any of metal in that structure to get it to burn…

I’d guess its mostly residue and perhaps some thinner whispy bits of metal left in the chamber from his welding, rather than actively burning the can (though without knowing anywhere near enough data points, I’m just judging from the video so I could be way off)

3d printed fuel sounds cool. But something I am working on, for several years now, is propulsion by using light. This would mean that no fuel would needed. I can cut down the weight of a vehicle in this way, and make it move extremely fast compared to solid or liquid fuel propelled vehicles

Cool, but, you can’t take-off from earth using only light. There are designs that use ground based lasers to heat the fuel (instead of chemical reactions) but you still need fuel (until you get to space and tiny thrust is okay).

This guy drives me crazy. Who would use plastic for a rocket nozzle? I is obvious to anyone this is a critical design error but apparently despite having plastic fail on him in 1,000 other projects it is still his go to material WTF. This guy tried to incorporate 3d printed plastic into to things it will obviously not work in.

Also I’d bet $ he didn’t make any thrust, that was just the Oxygen tank pressure most likely.

I’m all for trying things other say won’t work but what this guy does is way far from using knowledge of materials and some guesswork.

I assume you missed the part where he is making the nozzles out of 3d printed ceramics and not just plastics. I have been surprised at how far he has gotten with this material, personally. The unforseen difficulties when making parts using this process is also interesting to me.

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