Tokyo tanks
Encyclopedia
Tokyo tanks were internally-mounted self-sealing fuel tanks used in the B-17 Flying Fortress bomber
during World War II
. Although nicknamed "Tokyo
" 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
from any base in World War II.
These fuel tanks consisted of eighteen removable rubberized-compound containers, called cells, installed inside the main wings of the airplane, nine to each side. The main wings of the B-17 consisted of an "inboard wing" mounted to the fuselage and mounting the engines and flaps
, and an "outboard wing" joined to the inboard wing and carrying only the aileron
s. The Tokyo tanks were installed on either side of the joint (a load-bearing point) where the two wing portions were connected. Five cells, totalling 270 gallons (1,022.1 l) capacity, sat side-by-side in the outboard wing and were joined by a fuel line to the main tank delivering fuel to the outermost engine. The sixth cell was located in the space where the wing sections joined, with the remaining three cells located side-by-side within the inboard wing, and these four cells delivered 270 gallons (1,022.1 l) of fuel to the feeder tank for the inboard engine. The same arrangement was repeated on the opposite wing. The Tokyo tanks added 1080 gallons (4,088.2 l) of fuel to the 1700 gallons (6,435.2 l) carried in the six regular wing tanks and the 820 gallons (3,104 l) that could be carried in a tank that could be mounted in the bomb bay, for a maximum toal of 3600 gallons (13,627.5 l).
The first B-17s with factory-mounted Tokyo tanks were introduced to the Eighth Air Force
in England
in April 1943, with the arrival of the 94th and 95th Bomb Groups, but in June 1943 they began to appear in great numbers as replacement aircraft, and from the beginning of July, 1943, all replacement aircraft were so equipped. All B-17F aircraft built by Boeing from Block 80, by Douglas from Block 25, and by Vega from Block 30 were equipped with Tokyo tanks, and the entire run of B-17Gs had Tokyo tanks.
Although the tanks were removable, this could only be done by first removing the outboard wing panel, 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
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.
Bomber
A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...
during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. Although nicknamed "Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...
" 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
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
from any base in World War II.
These fuel tanks consisted of eighteen removable rubberized-compound containers, called cells, installed inside the main wings of the airplane, nine to each side. The main wings of the B-17 consisted of an "inboard wing" mounted to the fuselage and mounting the engines and flaps
Flap (aircraft)
Flaps are normally hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed an aircraft can be safely flown at and to increase the angle of descent for landing without increasing air speed. They shorten takeoff and landing distances as well as...
, and an "outboard wing" joined to the inboard wing and carrying only the aileron
Aileron
Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...
s. The Tokyo tanks were installed on either side of the joint (a load-bearing point) where the two wing portions were connected. Five cells, totalling 270 gallons (1,022.1 l) capacity, sat side-by-side in the outboard wing and were joined by a fuel line to the main tank delivering fuel to the outermost engine. The sixth cell was located in the space where the wing sections joined, with the remaining three cells located side-by-side within the inboard wing, and these four cells delivered 270 gallons (1,022.1 l) of fuel to the feeder tank for the inboard engine. The same arrangement was repeated on the opposite wing. The Tokyo tanks added 1080 gallons (4,088.2 l) of fuel to the 1700 gallons (6,435.2 l) carried in the six regular wing tanks and the 820 gallons (3,104 l) that could be carried in a tank that could be mounted in the bomb bay, for a maximum toal of 3600 gallons (13,627.5 l).
The first B-17s with factory-mounted Tokyo tanks were introduced to the Eighth Air Force
Eighth Air Force
The Eighth Air Force is a numbered air force of the United States Air Force Global Strike Command . It is headquartered at Barksdale Air Force Base, Louisiana....
in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
in April 1943, with the arrival of the 94th and 95th Bomb Groups, but in June 1943 they began to appear in great numbers as replacement aircraft, and from the beginning of July, 1943, all replacement aircraft were so equipped. All B-17F aircraft built by Boeing from Block 80, by Douglas from Block 25, and by Vega from Block 30 were equipped with Tokyo tanks, and the entire run of B-17Gs had Tokyo tanks.
Although the tanks were removable, this could only be done by first removing the outboard wing panel, 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
Valve
A valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category...
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.