Flat Spins Upright Spins and Snap Roll Spins

Описание: Spins are an autorotation that results from a stall with rudder input, generally with reduced power. A snap roll is an autorotation with rudder input and generally higher power or higher speed. One wing is stalled in a snap roll, both wings are stalled in a spin. Recovery from a spin usually happens when the elevator and rudder are centered. There are 4 types of spin: flat and normal, inverted and upright. Spins can be to the right or left and usually the aircraft has a different behavior for right, left and inverted.

The tricky bit is that all spins are unique and once in a while an unknown condition can develop in a spin making recovery much more difficult. Early jets had spin parachutes that could be deployed to break an uncontrollable spin. Once in a great while a spin can develop where autorotation continues after controls are centered. A bump of down elevator can break the spin or holding opposite rudder. There is a danger of reversing the spin with too aggressive opposite rudder input. Down elevator may actually increase the spin rotation in an upright spin. Opposite aileron may make a normal spin become flat.

Flat spins can be particularly dangerous as there is no airflow over the rudder or elevator except propwash. Full throttle may not stop the autorotation and may make the flat spin flatter. Generally a normal spin can be converted to a flat spin by applying opposite aileron and adding power.

Some aircraft flat spin better than others. The Jimmy Franklin Waco biplane has a perfect flat inverted spin that recovers easily. The Bobby Younkin Samson biplane also does a nice inverted flat spin. Sukhoi 26 aircraft can flat inverted spin easily though recovery can be tricky. The Sukhoi 26 can plop onto it's back out of a tail slide in a perfect attitude for beginning a flat spin.

Spins are a good way of losing altitude without building up airspeed or changing location. A nice spin looks elegant and is a low G maneuver. However, a spin can kill you and should never be done without high altitude practice. The most dangerous spin is the unexpected kind...out of a stall turn or a during turn in the landing pattern where airspeed gets too low. Stalls with rudder input are always a recipe for a spin.

Top aerobatic pilots have discussed the solutions to "stuck" spins. Often the only recourse is to bail out. Once the pilot has departed the aircraft, the machine may recover from the terminal spin. Why? The aircraft minus the pilot is now more nose-heavy and the controls are neutralized and generally the pilot shuts the engine off before hitting the silk. So one school of thought dictates that letting go of the controls and shutting the engine down to landing idle might bring about a spin recovery which won't respond to normal inputs. This obviously could be frightening as the ground comes up to meet the aircraft! Full power won't do the job. The stall must be broken, the nose must be moved down. A flat spin converted to a normal spin is a step in the correct direction.