folding fin

folding fin

[′fōld·iŋ ′fin]
(aerospace engineering)
A fin hinged at its base to lie flat, especially a fin on a rocket that lies flat until the rocket is in flight.
References in periodicals archive ?
Supercavitating projectiles, with the ability to hit underwater mines, have been tested, as well as the Advanced Precision Kill Weapon System and a laser-guided 2.75-inch folding fin aerial rocket.
It included an insensitive munition compliant composite motor case with an integrated wire tunnel, electro-mechanical actuators with folding fins, aerodynamic efficient ogive and tail fins, and novel flight software, according to an Army news release.
I ordered the biggest one, along with folding fins that strapped onto my wader boots.
The 122 mm, 66.5-kg rocket, designated 9M22U or M-21 OF, is spun first by a groove in the launch-tube and then by folding fins. It delivers an 18.4 kg blast-fragmentation warhead over a distance of 20.4 km.