Tokyo tanks were internally mounted

self-sealing fuel tanks A self-sealing fuel tank is a type of fuel tank, typically used in aircraft fuel tanks or fuel bladders, that prevents them from leaking fuel and igniting after being damaged. Typical self-sealing tanks have multiple layers of rubber and reinfor ...

used in the

Boeing B-17 Flying Fortress The Boeing B-17 Flying Fortress is a four-engined heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Relatively fast and high-flying for a bomber of its era, the B-17 was used primarily in the European Theater ...

and

Consolidated B-24 Liberator The Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models des ...

bombersDrop Tanks
November 4th, 1943 ''Flight'' p513 during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. Although nicknamed "

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.468 ...

" tanks to dramatically illustrate the significant range they added to the B-17 (approximately 40% greater with combat weights), it was also an exaggeration in that no B-17 ever had the range to bomb

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

from any base in World War II.

Description

These fuel tanks consisted of eighteen removable containers made of a rubberized compound, called cells, installed inside the wings of the airplane, nine to each side. The wings of the B-17 consisted of an "inboard wing" structure mounted to the fuselage which held the engines and flaps, and an "outboard wing" structure joined to the inboard wing and carrying the ailerons. The Tokyo tanks were installed on either side of the joint (a

load-bearing A load-bearing wall or bearing wall is a wall that is an active structural element of a building, which holds the weight of the elements above it, by conducting its weight to a foundation structure below it. Load-bearing walls are one of the ea ...

point) where the two wing portions were connected. Five cells, totaling capacity, sat side by side in the outboard wing and were joined by a fuel line to the main tank delivering fuel to the outboard engine. The sixth cell was located in the space where the wing sections joined, and the remaining three cells were located side-by-side in the inboard wing; these four cells delivered of fuel to the feeder tank for the inboard engine. The same arrangement was repeated on the opposite wing. The Tokyo tanks added of fuel to the already carried in the six regular wing tanks and the that could be carried in an auxiliary tank that could be mounted in the bomb bay, for a combined total of . All B-17F aircraft built by Boeing from Block 80, by

Douglas Douglas may refer to: People * Douglas (given name) * Douglas (surname) Animals *Douglas (parrot), macaw that starred as the parrot ''Rosalinda'' in Pippi Longstocking *Douglas the camel, a camel in the Confederate Army in the American Civil W ...

from Block 25, and by

Vega Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, an ...

from Block 30 were equipped with Tokyo tanks, and the entire run of B-17Gs by all three manufacturers had Tokyo tanks. B-17s with factory-mounted Tokyo tanks were first introduced to the

Eighth Air Force The Eighth Air Force (Air Forces Strategic) is a numbered air force (NAF) of the United States Air Force's Air Force Global Strike Command (AFGSC). It is headquartered at Barksdale Air Force Base, Louisiana. The command serves as Air Force ...

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in April 1943 with the arrival of the 94th and 95th Bomb Groups, equipped with new aircraft. By June 1943, aircraft that were so equipped began to appear in greater numbers as replacements, and from the beginning of July 1943, all replacement aircraft that did not have the tanks already installed were equipped before issue. Although the tanks were removable, this could only be done by first removing the wing panels, and so was not a routine maintenance task. A drawback to the tanks was that there was no means of measuring remaining fuel quantity within the cells. Fuel was moved from the cells to the engine tanks by opening control

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...

s within the bomb bay so that the fuel drained by gravity. Although the tanks were specified as self-sealing, vapor buildup within partially drained tanks made them explosive hazards in combat.

References

*Bishop, Cliff T. ''Fortresses of the Big Triangle First'' (1986), pp. 50–51. {{Aircraft fuel tanks Aircraft fuel system components Aerospace engineering Fuel containers