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I am not sure this engine can actually run. It's a little different to most DIY engines I think but it is hard to tell since there aren't enough details.

Is the combustion chamber here just a space between the compressor and turbine? I didn't notice any kind of flame tube in the design and I don't think a jet like this will work without one. You'd have far too much air from the compressor to be able to get the gas to burn in the chamber and if you can get it to burn you need extra air to mix with the exhaust so the temperature isn't too high for the turbo turbine. Getting the flame tube, which is controlling the mixture of the fuel and the air, just right is most of the trick in getting these sorts of engines to run. It can be a bit hit and miss!

Also with a centrifugal turbine the exhaust gas should enter from the side of the turbine rather than axially as it appears to here? Again it is hard to tell from the details given. I imagine it might turn with the gas flow axial but I don't know that it would extract enough energy from the exhaust to spin fast enough to get the whole thing to self sustain.

If it does run I am not sure the bearing system as designed would be up to the job. Turbos often have simple sleeve bearings that need quite a bit of oil pressure to run properly. The ones that do use ball bearings use quite fancy ones. A typical home made jet engine is going to be running at something like 30000 to 100000 rpm. Normal cheap bearings, even with lubrication, probably aren't up to that.

Still, hopefully they get this running and prove me wrong :) Please post an update and videos if you do! Good luck!

Oh, I should say I am not an expert but I have made my own jet using a turbo before and it took a lot of fiddling to get her to run!

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