Sidewinder engine on inside

Does anyone have experience of fitting a sidewinder engine on the inside of a profile fuselage? I'd like to do it on a new design.
Possible problems envisaged are:-
A. Tank will be on outside feeding fuel 'against centrifugal force' to engine. Also slightly longer fuel run.
B. Weight on inside
The transfer ports will be at bottom but don't see this as a disadvantage.

Any help would be appreciated
Adrian

This works well with diesels, but I have no experience of glo. Put the tank on the inside where the engine is. The transfer being on the bottom may give you starting problems but should run OK. If it's a Fox 35 you will have to mount the tank roughly 5/16" LOW.

>Does anyone have experience of fitting a sidewinder engine
>on the inside of a profile fuselage? I'd like to do it on a
>new design.
>Possible problems envisaged are:-
>A. Tank will be on outside feeding fuel 'against centrifugal
>force' to engine. Also slightly longer fuel run.
>B. Weight on inside
>The transfer ports will be at bottom but don't see this as a
>disadvantage.
>
>Any help would be appreciated
>Adrian

People have done this. I think it is called the "Texas" style and Bill Hopkins of Custom Models built all of his profile kits with this in mind. He used a plastic clunk tank which can then be mounted on the inside as well.

My question would be why would you want to do this? Although in theory it throws the fuel away from the plug for better running, with the outside mounted engine the fuel is thrown towards the plug every stroke so there is no change in characteristics anyway (not like going from inverted to upright).

The negatives are:
With any plane you need tip weight. Putting the engine and tank outboard adds that tip weight automatically--at least part, if not all of what is needed. Mount the engine and tank inboard and you have to add additional tip weight just to offset the (considerable) weight shift to the inside. And then you still need to add tip weight to the mix.

You also add drag to the inside. And since you have the line drag working on the plane to start with, you will now need to offset the additional drag of the engine. With the engine and tank mounted outboard, it offsets much (most, all) of the line drag already.

The engine will also blank a portion of the inboard wing. Since the inboard wing is flying slower, there are some who add a bit of wing area inboard to compensate. The outboard engine will help compensate. The inboard engine will merely make the outboard wing even more efficient.

And the real positives??

(I am still working on that.)

>And the real positives??
>
>(I am still working on that.)

It keeps the silencer from digging a groove in the ground on non wheeled planes flying over grass (!) and protects the engine crankcase and fixings from the leverage from the silencer in a crash.

It's not my preferred way either but I have an old design here which is non-wheeled and which wouldn't stand a silencer pointing downwards. Hence the question.

Can you put a wheel or skid on the plane, or, alternately, put a K&B GreenHead or Veco of the same time period. The exhaust on these points up when the engine is mounted outboard.

>>Does anyone have experience of fitting a sidewinder engine
>>on the inside of a profile fuselage? I'd like to do it on a
>>new design.
>>Possible problems envisaged are:-
>>A. Tank will be on outside feeding fuel 'against centrifugal
>>force' to engine. Also slightly longer fuel run.
>>B. Weight on inside
>>The transfer ports will be at bottom but don't see this as a
>>disadvantage.
>>
>>Any help would be appreciated
>>Adrian
>
>People have done this. I think it is called the "Texas"
>style and Bill Hopkins of Custom Models built all of his
>profile kits with this in mind. He used a plastic clunk
>tank which can then be mounted on the inside as well.
>
>My question would be why would you want to do this?

It was perfectly well explained Frank's profile bearcat article, and the followup in Stunt News. It doesn't necessarily help if you don't have a problem to begin with.

LAST EDITED ON Feb-08-04 AT 04:48 PM (CDT)
 
Having spent the last year flying a model from custom models with this setup (except the tank is also on the inside) there are only a few problems I've seen. First the weight being on the inside of the circle means extra wingtip weight is needed. Second the exhaust points up, people don't like holding a plane with exhaust spewing in their face, can be solved with a K&B 4011 engine. Third the eshaust runs down both sides of the fuselage which means more clean up and possible weight gain, small problem if the pushrod is also on the inside.

The engine performs well with no problems, setup is the same as with a sidewinder on the outside.

If you do the design put the tank on the same side as the engine. Get a K&B 40 and reverse the exhaust with the understanding that changing to normal exhaust later might cause problems.