Originally Posted by
waterbottle
A friend that flew Phantoms, 15C and E commented that the Phantom was faster. In fact he was very complementary about it in a number of areas over the F-15. Didn’t get into much detail, and not sure of the fits that he was comparing. His experience was F-4 in Vietnam and then F-15 through the 70’s and 80’s.
The operations manual for the USAF F-4C/D/E is on the internet if you look for it. Maximum sustained speed for the J79 powered Phantom (clean or with 4 AIM-7) was listed as Mach 2 / (IAS over 700 knots) above 30.000 ft or Compressor Inlet Temperature of around 121 Degrees C (which ever was reached first). However these limits were allowed to be breached for 5 minutes in any one flight and the aircraft could be taken to Mach 2.4 for a very limited period. I did read somewhere that the CIT limits on the Spey were lower than the J79 and that was one of the reasons that the UK engine powered Phantoms were slower. Airspeed limits with the wing tanks fitted was Mach 1.9.