Fuel dumping on the F-111

[Stuart Chapman]

Hi all.

You've all seen the 'cigarette lighter' fuel dump by the F-111 at airshows.

Can the F-111 just dump fuel normally (no fuel ignition)? If not, why not?

Stupot

[douga play]

Stuart Chapman wrote:
> Hi all.
>
Hi
> You've all seen the 'cigarette lighter' fuel dump by the F-111 at
> airshows.
>
> Can the F-111 just dump fuel normally (no fuel ignition)? If not, why
> not?
>
I have read that they use after burner to do this... so maybe without AB
they
dump without fire

> Stupot
Alex

[John Carrier]

"Stuart Chapman" > wrote in message
...
> Hi all.
>
> You've all seen the 'cigarette lighter' fuel dump by the F-111 at
airshows.
>
> Can the F-111 just dump fuel normally (no fuel ignition)? If not, why not?

Yes. Burning dumped gas is an airshow trick. RA-5C also did it. F-14
could as well, but it was unauthorized.

R / John

[Kurt R. Todoroff]

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.

[John Carrier]

"Kurt R. Todoroff" > wrote in message
...
> 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?

Been so long, I can't remember, but that sounds right. But it was
prohibited and the 100 foot flame trick would work in A/B (don't ask, don't
tell).

> 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.