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General control line discussion => Open Forum => Topic started by: sleepy gomez on March 18, 2009, 09:45:23 PM

Title: tune fuel tank like the Russians
Post by: sleepy gomez on March 18, 2009, 09:45:23 PM

I've been told that somewhere on a forum it was mentioned that the Russians were using an inboard tank with a sidewinder engine.  Something was said about tuning the tank.  How does this work?

Title: Re: tune fuel tank like the Russians
Post by: Bradley Walker on March 19, 2009, 11:17:57 AM

The fuel pickup of the tank is inboard of the spraybar hole.

If the airplane tries to over speed, the centrifugal force floods the engine and the engine slows down.  Pretty simple.

You tune the tank by shimming in/out not just up/down.

Title: Re: tune fuel tank like the Russians
Post by: sleepy gomez on March 20, 2009, 07:37:50 PM

Thanks Bradley.  Just the information I was looking for.  SLEEPY

Title: Re: tune fuel tank like the Russians
Post by: Lauri Malila on March 21, 2009, 01:20:15 PM

  Hi.

 Also, that way you get slightly leaner run in overhead maneuvres. It can be usefull sometimes. Another benefit of tank CL inside from venturi CL when flying in strong wind, is that you are able to set the engine leaner on the ground. As the plane accelerates, engine settles into richer run. With Retro engines, I usually adjust the tank CL 7-10mm inside from needle valve hole. L

Title: Re: tune fuel tank like the Russians
Post by: sleepy gomez on March 21, 2009, 09:06:21 PM

Lauri, how can you get the tank that close to the spraybar hole?  It would seem that the engine crankcase would keep it from being that close.   Looking down on the plane, the tank could be no closer than about one inch to the spraybar hole and this would interfere with mounting.    Help.

Title: Re: tune fuel tank like the Russians
Post by: Lauri Malila on March 22, 2009, 03:53:20 AM

 Sorry, my explanation was a little unclear..
 I mean 7-10mm distance between tank centerline and needle valve hole CL when you look at the model from top. So the tank is 7..10mm towards inside of the fuselage.
 On the other hand, in my new model the tank distance from needle valve IS about 10mm but that's a rear intake engine. Smallest possible distance does no harm, of course, but I don't think it changes a lot. It's still 130mm to the rear wall of the tank. L