Hi guys,

In modifying my plane, I noticed today that my tank sits MUCH lower than the carburator intake. I'm thinking this may be a problem, even though the tank will be lightly pressurized by part of the exhaust gas.

Before I cover the front part of the plane, I want to make sure I haven't made any severe mistakes. So, if it IS too high (keeping in mind the photo is pretty much level, so it is an accurate representation), which of these would you suggest?

* Cut landing gear and move it down.
* Bend landing gear (as I have done) and thus lower the front part more. (the gear is very strong, and the plane being slightly more than a pound, even rough landings should pose no problems).

I don't foresee doing many aerobatic moves, if that is of any relevance.

Thanks in advance!

EDIT: I have marked the tank output, the tank outline, and the fuel collection weight from left to right, respectively.

Superbump.

I think you'll be fine. your tank isn't that much lower than the engine. Lowering your nose gear isn't going to do a thing for you once you're in the air.....

Andy

All righty, thanks. Can anyone offer a second opinion? I'd hate to cover it and then have to take it off again and fix the problem. Kinda my fault that the engine is so high now (as I movied it forward to give me some fuel tank space), but still.

It's hard to figure what is what on that picture. But as Andy hinted at, "lower" doesn't mean lower when sitting on the wheels, it means lower when in straight and level flight. So, how are the tank and engine in relation to each other when the plane is "level" as it would be in flight? Wheels don't count .

Using the engine thrust line as "level", then the tank isn't really all that low, nothing that I haven't seen in plenty of planes. I'd say your best plan is to rotate the engine to a side-mounted or 45degree mounted arrangement if possible. Otherwise don't sweat it, to fly and see how it does.

Thanks, Montague. Even in level flight and without the wheels, the fuel intake is still a little bit higher than the tank. However, that was a good idea to rotate the engine if this doesn't work. I hope this baby can maiden this Saturday or Sunday: I can't wait!

I had a similar issue with an OS52 in a Mid-Star. Engine ran great until I inverted the plane. Then the mixture richened up since the carburetor no longer had to pull the fuel from the bottom of the tank. This made a difference since the bottom and top of the tank were not the same distance from the carburetor centerline. I finally installed a Perry VP20 pump and it runs great at all attitudes now.

If you check the manual on your engine, it will give you a "range" the FUEL PICK UP should be above or below the throttle bar or C/L of the carb. This range is FREQUENTLY 3/8" above or below the C/L of the carb. Many people prefer the sideways mounting for many reasons, including less variation in fuel draw when flying inverted.