E-7? terrain color?

[Kurfürst]

Originally Posted by Ballenato

So, you know what modifications were need to use it?
The factory simply ran a fuel pipe thru the cockpit floor, coming up on the right side corner, behind the seat. The pipe ran along under the edge of the canopy to a auxiliary fuel contents indicator, then thru the
instrument panel and firewall to the engine. Normal procedure was to start the engine with the fuel coming from the drop tank, then as the fuel
got low, to switch to the main tank, and jetison the drop tank.

That indeed worked this way on many Allied fighters according to the manual.

German fighters droptank worked different, though. On the 109 and 190, pressurized air tapped from the supercharger was fed into the droptank itself, which in turn forced the contents of the droptank, through a pipe into the main tank. Effectively, the engine was fed from the main internal tank all the time, and itself was replenished continously from the droptank. There was no fuel selector switch of any kind.

On the 109, the pipe leading from the DT to the MT was lead through the cocpit on the right side. A section of the pipe was made of glass, through which the pilot could observe simply and reliably wheter the drop tank properly feeds or not.

A classic 'Keep it simple, stupid' system.