A new spin-recovery technique for later-generation, Block 40/50, Lockheed Martin F-16s equipped with inlet-mounted pods is to be written into the aircraft's flight manual after investigation work by the US Air Force's F-16 Combined Test Force at Edwards AFB, California.

The test team discovered that inlet stores, such as LANTIRN navigation and targeting pods "-acted like a ventral fin forward of the centre of gravity, causing significant aerodynamic pitch coupling and inertia coupling, including a nose-up pitch acceleration". Aircraft configurations with large asymmetric loads and inlet pods demonstrated post-departure characteristics "-best described as highly dynamic spins", says the team, which found that "-deep- stall recovery procedures proved to be inadequate, and on two occasions the spin chute was deployed to recover the aircraft".

The General Electric F110 engine, which produced a "significant gyroscopic effect" at high angles of attack, also suffered "pop stalls" during the tests. The test team consequently developed an upright spin-recovery procedure which involves activating a manual pitch override (MPO) switch with the sidestick in a neutral position.

The MPO allows the pilot to take manual control of the tail and use differential horizontal tail without fighting against the digital flight-control system.

The combination proved effective, says the team.

Source: Flight International