Out of control in the A-7

As you might guess, testing an airplane to determine its spin characteristics can be a complicated thing. It has a BIG matrix! It has to be tested at all possible centers of gravity (CG), so lead weights have to be moved fore and aft in the fuselage. We had to look at all manner of external configurations, so bombs and tanks were continually loaded and unloaded. We even tested the airplane with three different engines! Then there were the flight techniques: straight-ahead 1g entries, vertical entries and accelerated entries (the airplane is placed in a hard turn pulling multiple g’s).

Once on the range, the test airplane was tracked by several ground cameras and transmitted 30 parameters (air data, control positions, engine status) to a ground station. It didn’t take us long to figure out that the A-7 didn’t really have a spin problem — we only encountered a handful of auto-rotative spins in the whole program! However, it had a LARGE issue with post stall gyrations (PSG) once it departed from controlled flight. These could be serious. For instance, we found it took a heavily loaded A-7 up to 10,000-ft to recover from a departure and PSG’s. Accelerated stalls resulted in high speed cartwheels that were shocking and disorientating to the pilot.

Fortunately, once we defined the problem the solution was fairly simple. First, we re-wrote the spin section of the pilot’s handbook to fully detail the A-7’s actual behavior in the post-stall environment. Second, we were successful in implementing in-flight, hands-on training of A-7 pilots in the replacement air wings. The loss rate of A-7 aircraft to “out of control flight” essentially went to zero.

Here are three brief videos — and I apologize in advance for their quality. The first shows a quick glimpse of a fully loaded test bird, followed by a separate shot of a left accelerated stall and a left departure. Cut two is a left accelerated stall with a right (over the top) departure. The last clip is a pretty good look at an autorotative spin.