CFTs have a reduced aerodynamic penalty compared to external drop tanks, and do not significantly increase an aircraft's radar cross-section. Another advantage CFTs provide is that they do not occupy ordnance hardpoints like drop tanks, allowing the aircraft to carry its full payload.
Disadvantages
Conformal fuel tanks have the disadvantage that, unlike drop tanks, they cannot be discarded in flight, because they are plumbed into the aircraft and so can only be removed on the ground. As a result, they will impose a slight drag-penalty and minor weight gain on the aircraft even when the tanks are empty, without any benefit. They can also impose slight g-load limits, although not always an absolute issue: the CFTs on the F-15E allow the same maneuverability without g-limitations.
Ground crew handling the CFT of an F-15EIsraeli F-16I Sufa, based on the F-16D Block 50/52+, with 2 CFT on the wing root.Russia MiG-29 SMT with the spinal conformal fuel tankBf 110D with Dackelbauch tankSupermarine Spitfire with a belly tankFrom the F-15C Eagle[1], all the aircraft of the F-15 family were designed and built to receive the conformal fuel tanks. The aircraft in question are the F-15C Eagle, the F-15E Strike Eagle and the F-15EX Eagle II.
The tanks were nitially known as FAST packs (for "Fuel And Sensor Tactical").[1] The first tests took place on the F-15B in 1974.[2] Initially, the project intended to include navigational equipment and infrared targeting sensors on the FAST pack (thus "Fuel And Sensor"). But the sensor part of the concept was never implemented, instead specialised pods are being used by the F-15 family, such as the LANTIRN for ground-attack missions.[1][3]
Each aircraft carries two tanks, with each 2,840L (750USgal) of extra fuel for a total of 5,680L (1,500USgal).[4] Despite their presence, the F-15C kept the hardpoints on the side of the fuselage for 4 × AIM-7F Sparrow missiles or bombs, some of the hardpoints are on the side of the FAST packs.
IAI (Israel Aerospace Industries) developed their own conformal fuel tanks and they are used on the Israeli F-15 (A/B, C/D, E, EX).[12] These have been manufactured since 1984.[13][14]
The F-16C/D Block 50/52+, the F-16E/F Block 60 and the F-16V Block 70/72 were reinforced structurally to receive two CFT mounted atop the aircraft near the wing root. Each tank adds a capacity of 850L (220USgal) for a total of 1,700L (450USgal).[15][16][17] The first aircraft with CFT was a F-16E/F delivered to the UAE in 2004.[18]
The current operators include: Bahrain[19][20], Bulgaria[21], Egypt[22], Greece[18], Morocco[23], Oman[24], Pakistan[25], Poland[26], Taiwan[18], Turkey[27], Singapore[28], Slovakia[21], UAE[18]. Future operators: Peru (aircraft selected for procurement in 2026)[29].
IAI (Israel Aerospace Industries) developed their own conformal fuel tanks and they are used on the Israeli F-16I Sufa. Each tank adds a capacity of 850L (220USgal) for a total of 1,700L (450USgal).[30]
The F-CK-1C (single-seat), and the F-CK-1D Brave Hawk (2-seater), are both prototypes. They have two CFT that are atop the wings, near the wing root.[39]
The US Navy planned to mount CFT on F/A-18 E/F Block III (and could have been retrofitted on Super Hornet E/F and Growler), but the plan was cancelled due to the practical considerations of space and maintenance at sea. Plus during some of the landing with the land-based arresting system (carrier landing simulator), the CFTs were heavily damaged due to the shock.[40]
Dassault developed and tested a Rafale equipped with two CFT in April 2001.[43] Each of the tank has a capacity of 1,150L (300USgal), for a total of 2,300L (610USgal). The tanks are located atop the fuselage, on each side of the spine.
Dassault exposed a Rafale equipped with CFT at the Paris Air Show 2025.[44]
BAE Systems tested in a wing tunnel a variant of the Eurofighter equipped with two CFT located atop of the fuselage on each side of the spine. They were designed to be retrofitted on every Eurofighter T2 and T3.[45][46]
Each of the tank has a capacity of 1,500L (400USgal), for a total of 3,000L (790USgal).
During the 2000s, Saab was assessing options to increase the range. One of the option was to add to CFT on the sides of the spine of the aircraft. The other that was later chsen was to develop the Gripen NG, which is today the Gripen E/F.[47]
Examples of distended internal tanks
Gloster Meteor with a belly tank
Distended internal tanks are fuel tanks that either create a bulge in the fuselage, or are mounted flush with the fuselage.
AVM (R) Ikramullah Bhatti (27 July 2020). "Faithful Warrior". Second To None. Directorate of Media Affairs Pakistan Air Force. Retrieved 27 August 2022.
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