While dumping fuel in the F-111, at least minimum afterburner thrust was
required to ignite the fuel stream. Non-afterburner core thrust possessed
insufficient temperature to ignite it since the fan mass flow mixed with the
core combustion products, thus lower its temperature. I would be interested to
know if any turbojet fighters had a fuel fump mast near the engine exhaust, and
if so, could their core thrust alone ignite the fuel stream.

John, I had a copy of the F-14A flight manual until my last move. I seem to
remember that the Tomcat dumped its fuel using only the fuel boost pumps (no
fuel tank pressurization), which yielded a somewhat low fuel transfer rate
through the dump mast. Did the low fuel transfer rate effect a low fuel
exhaust velocity through the dump mast, thus causing the potential for the
flame to contact the fuselage?

The F-111 normal fuel dump mode was accomplished with fuel tanks pressurized.
If memory serves me (I no longer have my Vark flight manual either) normal fuel
dump transfer rate was approximately an order of magnitude greater with tanks
pressurized than with tanks unpressurized. The F-111 had no restriction on AB
use during normal fuel dumping operations, but (again) I can't remember if it
had AB use restrictions during non-pressurized fuel dumping operations.
Perhaps there was language contained in a caution.





Kurt Todoroff


Markets, not mandates and mob rule.
Consent, not compulsion.