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In the film "Memphis Belle" there is a scene in which the titular plane is successfully put into a steep dive in order to extinguish an engine fire.

This may have been the inspiration for a similar scene in the trailer for the forthcoming "Masters of the Air", where the same aircraft type (Boeing B-17) is also put into a dive to extinguish a fire. (As it is the very first flying scene depicted, I presume it is successful, rather than the plane disintegrating as the weakened wing is torn off, condemning those crew not already burned to death to their doom.)

Wikipedia states that "A dive may also be used as an emergency maneuver, for example to extinguish an engine fire" but provides no sources. Superficially, it makes sense, like blowing out a candle.

I can find only one source which states this was attempted, in a Lancaster in 1943. But the actual citation for the DSO awarded - testimony of a real aircraft fire - suggest that the pilot was actually trying to find somewhere safe to land -

Whilst over the target area, the aircraft was attacked by an enemy fighter from close range. Its gunfire exploded some incendiary bombs which had failed to release and a fire quickly developed in the bomber. The fuselage became a mass of flames reaching through the mid-upper turret manned by Flight Sergeant Dove. Ammunition in the turret boxes and ducts commenced to explode in all directions. In the face of an appalling situation, Flight Sergeant Dove coolly remained at his post. Although he was burned about the hands and face, he manned his guns with grim resolution, skill and accuracy. He delivered a devastating burst at the attacker, which had already been engaged and hit by the rear gunner and succeeded in destroying it.

Disregarding the roaring flames, he then descended from his turret and went to the assistance of Sergeant Airey, the rear gunner, who had been wounded, and extricated him from the rear turret. The situation had become extremely critical and Sergeant Hazard ordered the crew to prepare to abandon aircraft. When informed that one of his comrades was helpless he decided, in spite of the grave risk entailed, to attempt a forced landing. Meanwhile, Pilot Officer Gates, assisted by Sergeants Williams and Bain bravely tackled the fire with extinguishers and succeeded in getting it under control. The aircraft was now down to 800 feet but, as the fire had subsided. Sergeant Hazard quickly decided to attempt to fly the badly damaged bomber home.

Japanese aircraft in flames, struck by anti-aircraft fire from USS Hornet A real combat plane fire (source)

Is putting a plane into a dive a recommended, or even plausible, way of extinguishing a fire, or is it an entirely fictional device?

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2 Answers 2

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The way it's been shown, as the first and only response to a fire, it's fictionalized, but it's realistic that the pilot might dive.

The procedure for extinguishing an engine fire begins with shutting it down, cutting off fuel supply. Fuel flowing into a hot engine will maintain a fire. "Blowing out" a fire on a running engine by flying faster is not likely to happen. I was perplexed as to why they kept that engine running in the movie, given it was a 4-engine aircraft, easily able to lose one.

Fuel or engine fires cannot even be extinguished by supersonic flight - this report considers fuel fire for supersonic planes a worse, not easier problem. To extinguish a fire with air, it has to move faster than the flame front, blowing the burning gas, which is hot, away from the combustible material. This removes the heat element of the fire triangle (or tetrahedron).

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To do this, you need to push away the entire flame front. Leave one hot item - above the fuel's self-ignition temperature - in the vicinity of the fuel, and the fire will continue. This works when blowing out a candle, because it's completely in the stream of your breath. Now put that candle inside a protective tube, covering part of the flame, or insert a metal rod that will stay hot, and that won't work.

An exterior fire can be extinguished by flying fast, say if you set napalm on the top of a metal aircraft on fire. Small fires inside a jet engine can self-extinguish, being in a fast airstream. But a fire outside is safe to begin with. Military jets show off by dumping fuel and igniting it with an afterburner, called "dump&burn"; some fuel is left unburned.

If you have an engine on fire, or, worse, a fuel tank fire, the problem is on the inside. What's inside is at least partially shielded from the wind, and will continue to burn.

However, with an older, particularly an air-cooled engine, which have a lot of airflow, it will have the effect of cooling the engine, provided it has been shut down first. That effect can help extinguish a moderate sized fire, like that in the movie. But other steps have to be taken too.

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  • $\begingroup$ Auto ignition temperature for aviation fuels is around 210C. If I had no other option I would be inclined to give it a try, certainly if starting from relatively high altitude. $\endgroup$
    – Frog
    Jan 28 at 20:10
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This is a recommended procedure for many aircraft. For example, the engine fire checklist for a C152 goes:

  1. Mixture – IDLE CUT-OFF.
  2. Fuel Shutoff Valve – OFF.
  3. Master Switch – OFF.
  4. Cabin Heat and Air – OFF (except wing root vents).
  5. Airspeed – 85 KIAS (If fire is not extinguished, increase glide speed to find an airspeed which will provide an incombustible mixture).
  6. Forced Landing – EXECUTE (as described in Emergency Landing Without Engine Power).

Note that it's not dive or land, it's dive and land. If you turn the engine back on you'll likely reignite the fire. In a multi-engine airplane you might be able continue on the remaining engine(s), but you'd likely only do so if the risks of a forced landing are dire.

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