90
$\begingroup$

As seen in multiple pictures:

First, this one, it appears the aircraft is spraying copious amounts of fuel into the exhaust!

Surely this provides no thrust, not in the way an afterburner (which the F-111 has!) does.

Is it perhaps as an alternative to flares for anti IR missiles? It seems logical, but I don't think so, because I've seen it on takeoff too!

From this image, it looks like the aircraft is spraying COPIOUS amounts of fuel into the exhaust!

At any rate, it is QUITE badass!

enter image description here

EDIT: YouTube video!

EDIT: Can any other aircraft perform this?

Improve this question
$\endgroup$
6
  • 99
    $\begingroup$ It's not actually fuel, but US currency that it's dumping behind it. $\endgroup$
    – Keegan
    Oct 14, 2014 at 0:43
  • 37
    $\begingroup$ @KeeganMcCarthy given that only the Australians do it regularly, and that only during displays, it's actually Australian currency. $\endgroup$
    – jwenting
    Oct 14, 2014 at 8:25
  • 6
    $\begingroup$ The real question is why don't all planes do this? $\endgroup$
    – corsiKa
    Oct 17, 2014 at 14:18
  • 4
    $\begingroup$ I have been told by a former F-111 pilot that this maneuver is called "the Zippo trick." $\endgroup$
    – Skip Miller
    Jan 8, 2015 at 21:46
  • 4
    $\begingroup$ Pilot had beans for breakfast? parp FHOOOOOSSHSHHHHH!!!! $\endgroup$
    – Criggie
    Dec 20, 2016 at 6:45

5 Answers 5

Reset to default
114
$\begingroup$

The F-111 has, like many aircraft, a fuel dump port so it can get rid of a lot of heavy fuel rather quickly. Most aircraft have the dump ports on the wings, the F-111 designers put it in the tail between the engines. End result is if you dump fuel and briefly light the afterburner you will ignite the liquid fuel in your wake creating a rather spectacular trail of fire.

Aerodynamically it's completely useless, financially it's very expensive, you'd only do it in combat if you were suicidal as it greatly increases your IR signature right where you don't want it, but at an airshow it does look totally badass, especially as the afterburner is adding a lot of noise at the same time.

I would expect any pilot who does a dump-and-burn outside of an airshow (or an emergency) will have his own tail set on fire by the air wing's commanding officer.

The SR-71 had a similar issue - it leaked like a sieve on the ground. Rotating for takeoff would occasionally set fire to the JP-7 on the runway leaving a burning trail behind it much like the Road Runner.

Reply to the video: watch the takeoff section carefully. You can clearly see the afterburners come on before the fuel dump starts.

Reply to about half the comments: Highly unlikely they designed it to do this. The F-111 was one of the earlier swing-wing planes, that meant that you can't put much on the wings. And as the bigger tank is in the fuselage anyway, someone would have looked at the space between the engines and thought it was just right for a dump pipe. The flame effect was probably discovered later.

Improve this answer
$\endgroup$
17
  • 40
    $\begingroup$ any links to pictures or videos of the SR-71 leaving a burning trail would be awesome. $\endgroup$
    – BeowulfNode42
    Oct 14, 2014 at 5:57
  • 4
    $\begingroup$ @user50849 It also has uses in an emergency, where you might find yourself above an airfield about to land, but with too much heavy and flammable fuel: you want as little fuel as possible on a crash landing, but you don't want to fly in circles to burn fuel, so you can use a fuel dump port instead. $\endgroup$
    – cpast
    Oct 14, 2014 at 17:22
  • 31
    $\begingroup$ @user50849, it's not useless to dump fuel, and it's not useless to use the afterburners, but the only reason you'd do both in conjunction is for air shows :) $\endgroup$
    – Jason
    Oct 14, 2014 at 20:33
  • 6
    $\begingroup$ @LorenPechtel, heat-seeking missiles home in on the exhaust plume and then, like all anti-aircraft missiles, explode in a shaped explosion designed to take out a nearby airplane. A dump-and-burn will just make the exhaust easier for the missile to track. $\endgroup$
    – Mark
    Oct 16, 2014 at 19:37
  • 3
    $\begingroup$ "The F-111 was one of the earlier swing-wing planes, that meant that you can't put much on the wings." The F-111 had four pylon store mounts on the wings, each capable of holding up to 5000lb of ordnance. $\endgroup$
    – Carlo Felicione
    Dec 11, 2016 at 4:39
70
$\begingroup$

There was at least one occasion when the dump-and-burn was used in combat. During the 1986 attack on Libya

the U.S. pilots, desperate for fuel, jostling with one another in the air to get access to aerial refueling tankers. Unable to break radio silence, they could not locate the giant KC-10A Extenders and KC-135R Stratotankers that would keep them from crashing into the sea. An F-111 pilot finally solved the problem by doing a "little torching," as he dumped some fuel and ignited it with his afterburner, "creating a huge explosion that both lit up the sky and pointed the direction to the tanker"

Improve this answer
$\endgroup$
6
  • 9
    $\begingroup$ @reirab though technically it wasn't done IN combat. It was done post-combat during a combat mission. But maybe I'm splitting hairs here. $\endgroup$
    – jwenting
    Oct 15, 2014 at 6:32
  • 8
    $\begingroup$ For what it's worth, this use in combat is less suicidal than breaking radio silence. $\endgroup$
    – corsiKa
    Oct 16, 2014 at 20:18
  • 5
    $\begingroup$ Breaking radio silence might get you more in trouble with YOUR side, not the enemy. $\endgroup$
    – Bassinator
    Feb 20, 2016 at 0:41
  • 3
    $\begingroup$ Sorry to ask but how dump and burn help a fighter pilot find a tanker when they cannot break radio silence? $\endgroup$
    – vasin1987
    Oct 3, 2016 at 18:54
  • 5
    $\begingroup$ @vasin1987: I assume this was during the night, so they couldn’t see the tanker. They briefly turned on the lights that way. $\endgroup$
    – chirlu
    May 24, 2017 at 18:54
26
$\begingroup$

I used to be an F111 test engineer; the jet can hold about 19000 liters of fuel (without external tanks). At 0.81kg/Liter, that's 15390Kg (33,939 Lbs) of weight, which is substantial (the empty weight of the jet is 45200 Lbs / 20,500 Kg). Basically with a full load of fuel, the jet is 75% heavier.

Although the giant flame plume is cosmetic, the F111 can dump fuel like this in case you need to quickly reduce the weight of the aircraft; in-flight emergencies are one possible reason to reduce weight quickly. The fire is because the pilot lit the afterburners whilst dumping fuel. Assume you loose your flaps, or maybe you discover the brake lines are leaking... if you had to land on a short field (such as a small civilian airport), it makes sense to dump your fuel so you have a better chance of stopping quickly.

Improve this answer
$\endgroup$
4
  • 5
    $\begingroup$ I am interested, how long can an aircraft sustain this? How long can he dump fuel before he doesn't have enough to land? $\endgroup$
    – Bassinator
    Oct 14, 2014 at 21:38
  • 6
    $\begingroup$ @HCBPshenanigans You can land an aircraft with no fuel, so I guess the answer to the question in your comment is "until the tanks are empty." $\endgroup$
    – reirab
    Oct 14, 2014 at 21:51
  • 3
    $\begingroup$ @reirab not really. There might be technical limits to the length of time the fuel dump valve can be opened. And the burning trail of fuel might possibly damage the aircraft, so there might be a time limit there as well to prevent flames from reaching back into the fuel dump system for example. $\endgroup$
    – jwenting
    Oct 15, 2014 at 6:34
  • 2
    $\begingroup$ @jwenting I was referring more to the 'How long can he dump fuel before he doesn't have enough to land?' question. Unless you're outside of glide range from somewhere to land, there's not really a minimum amount of fuel needed to land, since you can land with no power. That's not to say it's a good idea, but it is possible. Since this answer was more referring to conventional fuel dumping (as opposed to setting the dumped fuel on fire with afterburners,) I was answering more with that in mind. There might be a limit for actually setting the fuel on fire. $\endgroup$
    – reirab
    Oct 15, 2014 at 14:39
18
$\begingroup$

We did have one "practical" application in "torching" as we used to call it: It was great way to find a Lead aircraft in a night formation to complete a night rejoin. Also we often considered it as a useful combat technique that if we got attacked by another fighter we would plan to start a dive towards the ground and we would do a short torch just before leveling off since the flash would clearly distract the attacker and make them think we hit the ground and break off the attack.

Improve this answer
$\endgroup$
3
  • 1
    $\begingroup$ This does not attempt to answer the question (although it is cool information that would be appropriate for a comment). $\endgroup$
    – dalearn
    Dec 31, 2018 at 1:11
  • 5
    $\begingroup$ Looks to me like this absolutely answers the "why" question as stated. $\endgroup$
    – Ralph J ♦
    Dec 31, 2018 at 2:54
  • $\begingroup$ @RalphJ the way I see it, this answer provides lots of cool information but if every other answer was deleted, a viewer would not have their question of “what is it doing” answered. Since this is the case, it would be more appropriate as a comment because it helps improve the question. $\endgroup$
    – dalearn
    Dec 31, 2018 at 12:30
3
$\begingroup$

The "Dump and Burn" as it was called here in Australia was used for 'effect' at air shows and for 'promoting' the Air Force as a great place to be.

The 'effect' was really quite spectacular. And frightening to those who saw it for the first time, like here in Brisbane, resulting in many phone calls to the police of a OFO sighting.

As used by some American pilots in SVN on missions to light up the area they were flying through too, for a better idea of just how close to the ground they were.

The Fuel Dump Atomizer Nozzle

A 'dump and burn' over Brisbane in the 80's, when the F-111's were 'active'.

Improve this answer
$\endgroup$
1
  • 1
    $\begingroup$ Welcome to Aviation.SE! If you have extra details, please improve your answer instead of leaving a comment which may be overlooked. $\endgroup$
    – dalearn
    Dec 31, 2018 at 1:13

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .