Ferry tank

A ferry tank allows the range or endurance of the vehicle or aircraft to be extended.

The first ferry tanks were drop tanks that fit externally on the aircraft and were used primarily by the military, allowing combat aircraft to both travel longer distances and remain in combat longer, giving advantages to air forces that utilized them on their planes.

But they also made the planes vulnerable to small arms fire.

[1] Military forces often utilize external ferry tanks, allowing aircraft to travel greater distance or remain in combat longer.

For example, external ferry tanks made possible the Israeli Air Force raid on the Osirak nuclear reactor known as Operation Opera.