inverted flight & 3d.

| Me and a friend are active in E-flight. On the field we got hit by a dump | question. | How can an airplain or heli fly inverted withoud that the fuel line sucks | air ?

The fuel tank has a `clunk' that gravity pulls to the bottom of the tank along with the fuel. Here's a picture --

Note that the tube that the clunk is on is flexible. So if you turn this over, the clunk again goes down, and now it's resting on the top of the tank.

Got it? Works pretty good for something so simple.

One word: Clunk. Fuel tanks have two lines (mostly) in the tank. One returns pressure from the muffler. The actual fuel line has a flexible line inside the tank that reaches to nearly the rear wall of the tank and has a weighted end called the "clunk". This weighted end will fall to whatever the bottom of the tank happens to be at any given moment. When inverted it falls to the top of the tank.

ok !!

For some models, using engines with no throttle, a fixed fuel feed is used so that the engine can be stopped by flying inverted for a short while. I believe some of the pylon race guys do (or used to do) this to save the weight of the throttle servo.

I've done it with small diesel powered planes when I only had a two function radio.

It's no problem for "positive G" manouevres, and even very short periods of inverted can be accomplished - you just have to remember to roll upright before the engine stops, and/or do your inverted flying while the tank is still nearly full.

Malcolm