Originally Posted by
Hueymeister
what are the open 'flap' things toward the back of the engines for?
Auxiliary Air Doors, two underneath the fuselage as well, the two on the upper fuselage are unique to Spey engined Phantoms. Their function is to open below 210kts (iirc) to provide additional air to the engines, they also blip open at speeds above 210kts to vent excess engine bay pressure, I think at +10 psi above atmospheric (iirc), I can't remember the exact figures and I can't find the relevant pages in the AP101 at the moment!
-RP