Originally Posted by
Discorde
Quick tech question: what are the relative merits of gear-type fuel pumps over diaphragm pumps?
In most cases none. In general, the pump requirements are determined at the design stage and selected accordingly.
Do most small aero-engines use the latter and, if so, why?
My guess, the simplicity, durability, and cost effectiveness of diaphragm pumps is the reason they are more popular on small aircraft engines.