Hi Guys.

I'm putting my old air start AMT Pegasus into my Boomerang XL.
As it's a heavy lump, so I'm positioning as far forward as I can to avoid excess lead in the nose.
Trouble is, there is only a 1" gap between the turbine and fuel tank.
Is this enough clearance for the turbine to breath properly ?

The tank is securely gripped by its neck and cannot move aft.

Thanks.

run the turbine out of the model, on the bench and write down temperature, RPM, ...

and try to run her in the model and see if changes...

i think if she don't get enough air, she will run higher on temperature and not full round...

but from the images she looks very close to the tank..

Maybe you can use a different tank which will give you more room

Mark

I have a similar installation in my XL, though a little more distance, but the engine will draw in what it needs, it dos'nt have to be funnelled in. Try a before and after as has been suggested.

IB

You may want to add 2-3 [link=http://en.wikipedia.org/wiki/NACA_duct]NACA ducts[/link] to the XL top section just forward of the turbine. Should help get more air to it.



Good luck,
Edgar

From what I have been told, you only need 1.5 times the compressor area, and I would think by looking at the picture that it should not be a problem. I asked Dean Wichmann, pretaining to my JHH Panther as he put a Ram 500 in a JHH F-86. Check out jet hangars website and look at the pics in the turbine installation page.

I don't think it's a problem either, the engine will take what it needs, and there is a lot of room there to get what it needs.

I wouldn't run it out of the airplane and get data personally, The engine doesn't draw from directly "forward" it draws from everywhere it needs to, including up down, and all around, even from behind the engine intake in the right configuration for that to happen.

Spartan

I'm using an airstart olympus/AT450 and can attain proper CG w/o lead. I'm using (2) 3600 NiMh batts for the airborne system and a 2000 LiPo for the ECU.

I think you'll be ok with the required air for the engine. remember the engine is going to draw the air from wherever it can. the inlet system in the jet will provide plenty of air for it to draw from. However, if you're seeking smoother airflow to the face of the engine then consider moving the engine back slightly.

my engine inlet bellmouth bisects the front engine mounting former. i.e. front case fuel, air, propane fittings just barely reach the former.

enjoy

buck

The shape of the bottle looks like it was made for feeding air to that turbine.[8D]

Spartan Missile,
You should have no problem with the turbine if you leave it where it is, but if you feel you must move it two or three centimetres back it will make virtually no difference to the CG.

Try it and check the CG by suspending the model from the bulkhead right in front of the turbine and you'll find moving it makes so little change to the CG position it has no effect on the XL.

Despite the turbine weight, it is so close to the CG point it hardly moves it. Maybe 3 or 4 MM.

I've tried numerous turbines and moved them fore and aft in my 3 XLs, and that's what I found.
Alan

If it were me I would increase the gap as much as practical. Sure, the engine will draw air from everywhere including behind BUT at high throttle settings you need a smooth flow from directly in front to avoid flameouts.

Hope that helps, Rob.

Good morning Chaps, thanks all of you for the suggestions.

I forgot to mention that my XL is the older Mk 1 version, and I added some mesh on the intakes as a FOD guard. I might have to put some NACA slots on the turtle deck if the air intake is restricted. I think I would be better off with a FOD guard on the turbine, as there is always the risk of a loose nut/bolt/washer lurking inside the fuselage !

I'll keep an eye out for high EGT and it's good to know that the plane is not sensitive to CG, so I can move the turbine back a bit if I have to.

With a bit of luck I won't have to change anything. I'll do a test run next weekend. I get 2 days off for Easter holidays, yippee