Self-sealing fuel tank
Self-sealing fuel tanks were developed primarily during the Second World War , in order to prevent the loss of fuel and ignition , especially in the case of tanks for military aircraft, after being shot at. Today the technology is also used in motor sports vehicles, armored military and civil vehicles.
history
The development of self-sealing tanks began as early as the First World War when J. Imber presented the concept of an external rubber seal that encompassed the entire tank, and its effectiveness was demonstrated. Later attempts to armor aircraft fuel tanks quickly turned out to be impractical because of the increase in weight. During the investigation of damage it turned out that the exit holes were usually larger than the bullet holes because of the projectiles in a tailspin.
During the Second World War, self-sealing tanks were developed on the British side by the company Fireproof Tanks (now part of GKN ) and used in aircraft of the Supermarine Spitfire , Hawker Hurricane and Avro Lancaster models. These tanks were covered on the inside or outside with a layer that contracted after a hit and thus closed the opening.
From the end of 1939 a standard procedure was used for German fighters and bombers, which consisted of three layers lining the tank. From the inside out, these were:
- 3 mm chrome leather
- 3 mm unvulcanized rubber
- 0.5 mm slightly vulcanized rubber
If fuel escaped from the tank after being shot through, it caused the non-vulcanized rubber to swell and thus sealed the tank. However, when the Royal Air Force introduced the 20 mm Hispano cannon as a fighter armament, this method was no longer able to seal the large bullet holes that were created.
In 1941, James Merrill, a Goodyear chemist , received the patent for a process very similar to the German one. It was a two-layer rubber coating inside the tank. The inner layer of vulcanized rubber was impervious to the fuel, while the second layer was not vulcanized. If the impermeable layer was destroyed, the unvulcanized rubber came into contact with the fuel, swelling and sealing the damaged area. This functional principle finally caught on. From 1942, the tank was first installed in Chance Vought F4U aircraft , and later also in other types. Also in 1942, Fireproof Tanks developed the first flexible aircraft tank as an additional tank for the Spitfire MkIX. This model was also self-sealing and consisted of different layers of rubber. Numerous aircraft were equipped with the new tanks. Until the end of the war, however, numerous aircraft with conventional tanks continued to be produced.
Further development during the Second World War concentrated on making the self-sealing tanks resistant to the sudden overpressure that comes with a projectile hit.
Newer models
Most military aircraft today have self-sealing tanks, even if only some of the technology from the Second World War is still used. In particular, it is unsuitable for aircraft with high altitudes because the tanks must be under pressure in this case. An alternative is to fill damaged tanks with foam , which means that the individual foam cells do not contain a sufficiently large amount of the fuel-air mixture to cause an explosion. Alternatively, empty tank cells can also be filled with a non-flammable gas, which displaces the explosive fuel-atmospheric oxygen mixture or renders it harmless. This method is used in the Lockheed Martin F-22 , among others .
Web links
Individual evidence
- ↑ "THE IMBER SELF-SEALING PETROL TANK". In: FLIGHT of December 11, 1919
- ^ Alfred Price: Heinkel He 111, International Air Power Review . Vol. 26, p. 138