Here is a question on a myth or possibly truth I just don't know. Did early jets shoot themselves down because they were faster than their bullets? Does not seem correct to me considering the FPS most military aircraft based weapons fire at in comparison to the max speed of jet.
An F11F on test did shoot itself down, but not because it was faster than the shells from its 20 mm guns -- the F11F was barely supersonic, if at all, so its max speed was about 350 m/s, vs about 800 m/s for the shells from its guns. The story I've heard is that it fired them while climbing, then leveled off and was, by a terrible coincidence, some distance down range at the same time: the shells had a greater speed but the length of their path and their speed along the path meant they took the same amount of time to travel along that path as the aircraft did to travel along a shorter path at lower speed.
Did early jets shoot themselves down because they were faster than their bullets? Does not seem correct to me considering the FPS most military aircraft based weapons fire at in comparison to the max speed of jet.
I believe your suspicions are absolutely corect. The reason for this is that the projectile's muzzle velocity will be added to the aircraft's speed (for forward facing guns), so the 500 m/s of aircraft velocity would add to the 800 m/s of muzzle velocity and the shell would be seen as moving at 1300 m/s to an observer on the ground (note that this is a very big deal: the ground speed of an A-10 is added to the ground speed of the GAU-8 rounds, which helps them make better holes in tanks). While the shells will slow down and the aircraft won't, they'll also fall towards the ground and the aircraft won't. Some numbers:
The Grumman Alley Cat is flying straight and level at 500 m/s, when it fires off its 20 mm gun, which has a muzzle velocity of 900 m/s. An observer on the ground sees the aircraft go 500 meters in the next second. The shells slow down, losing, say, one-half their muzzle velocity (remember this is
relative to the aircraft) and have traveled 950 meters. OK; the plane hasn't caught up. In this second, they've also fallen 5 meters below the flight path, so the plane would fly right over them.
If I reverse that and have the plane traveling at 900 m/s and the rounds at 500 m/s, they'll still drop that 5 meters, and, assuming again they've lost half their muzzle velocity, so they're traveling at 250 m/s relative to the aircraft, they'll have traveled 250 m farther than the plane.