[dcb]

lol, I think archimedes did that first, not exactly a paddlewheel though.

but, these restrictions, it sounds like a simple pressure set up, like a simple manometer and a bead in the fuel line for a reading fuel flow on a pressurized line. Would fuel line and return line signals on two sides of a manometer cancel out the return line and leave the consumed fuel rate, on a graduated tube ? Sorry if this is a dumb question.