New to the group, could use help with an equation

[propellanttech]

Aug 29, 2011 0:21:46 GMT -5 Johansson said:

If you are going to build a much smaller engine first you might as well build a well tested design like the KJ66 or MW54, since you cannot simply scale the engine up later it feels like a waste of effort to build one from scratch if all you want to do is to test air bearings in a working gas turbine.

If I were you I would build the full scale engine directly instead of spending years building a scaled down version of it.

I agree, but I haven't found a suitable turbine wheel at the moment.

I'm still working to find a suitable turbine wheel, and in the mean time, I'm exercising my brain with some drawings. It is a good exercise, and I'm learning things I've never drawn before (venturi holes in combustion chamber).

I plan to build the full size, provided a suitable turbine wheel can actually be obtained.

If that comes to pass, I'll build a small kj66 derivative, with air bearings.

James

[propellanttech]

Here is the shaft tunnel Assembly. It uses wave washers, but I don't have them included here.



James

[propellanttech]

Here is an update with the wave spring. I personally think this is the best preload idea of all the KJ66 derivatives.

[propellanttech]

After a lengthy discussion with "Racket", I have decided to change my direction.

I think making a turbine for a man rated aircraft is really not feasible at this point in time. Instead I'll take a JSF100 and convert it to a turbo fan in a pusher configuration. It will be cheaper in the long run for the purpose.

But.....I am still going to build a turbine. Probably aiming at 50 lbs of thrust. I will probably use an 84 mm compressor and axial turbine.

Since I have decided to change directions, I will also change the drawings to match.

I am going to use Johns method of diffuser design, which doesn't have the independent blades on the sides. I think this will reduce the cost of the diffuser. I have the knowledge to make it, just not the equipment. I can output the actual cad design for a machinist to make the part reducing the labor for programming.

James

[Johansson]

I think you are making a wise decision going for a JFS100 with a DIY turbo fan instead of a home built engine, you get the reliability of the JFS100 and you will still have months of fun work ahead with the fan section.

For 50lbs of thrust there should be readily made cast inconel turbines out there, another approach would be to make your own turbine wheel out of a sheet of inconel. Much more interesting and awarding to make it yourself in my humble opinion.