Conformal fuel tank


Conformal fuel tanks are additional fuel tanks fitted closely to the profile of an aircraft that extend the endurance of the aircraft.

Advantages

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 actually allow the same maneuverability without g-limitations.

Examples

Conformal fuel tanks

Distended internal tanks

Distended internal tanks are fuel tanks that either create a bulge in the fuselage, or are mounted flush with the fuselage.