Airplane Spins

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Before you begin spin training, talk with the flight instructor and get a feel for his or her spin training experience. Then check out the airplane the instructor wants you to use. Many aircraft are not certified for spins; the certification is based on passing specific tests laid down by the FAA. If you don’t feel comfortable with what you see and hear, find another instructor that will meet your needs.

Spin definition
I have heard spins described in various ways, often with expletives scattered amongst the description. There is no mystery; for a plane to spin, first both wings must have stalled. Second, you must have a situation where one wing has a greater angle of attack than the other. The spin usually swings around the wing with the highest angle of attack. Just a simple yaw motion at the time of stall is enough to cause an apparent difference in angle of attack between the two wings. Since the outside wing is moving at a higher speed due to its rotation, the angle of attack at the tip will be much less than the tip of the inside wing. Poor rigging, propeller torque, and even sloppy footwork from the pilot may be sufficient to induce the initial spin entry.

Whatever the reason, the stalled plane then begins to yaw in the direction of the wing that is more stalled and the plane begins to slip in the direction it is beginning to yaw. As the plane yaws, the situation becomes worse as the side of the fuselage, the vertical stabilizer, and other vertical surfaces weathervane into the wind. The asymmetrical lift also results in a rolling moment, causing the plane to roll in the direction of the stalled wing. Due to the yawing, rolling, drag, and centrifugal forces at work, the plane continues to pitch nose down, rolling and yawing, until the spin is fully developed. Each plane reacts differently during the course of a spin; the same plane can even exhibit different characteristics, depending on how it is loaded and other factors. The pitch angles and rate of rotation during a spin will also vary as the spin progresses.

Once a plane enters a spin, it will usually remain there until recovery is initiated. If you are flying a plane certified for spins, multiple-turn spins are safe as long as you remain within the limits specified by the manufacturer. A note of warning, though—never purposely spin a plane that is not certified by the manufacturer for spins. For those aircraft certified in the normal category, the manufacturer is only required to demonstrate that the plane is able to recover from a one-turn spin, or three second spin, whichever takes longer. If you spin a plane in this category, once the plane passes one turn, you have become a test pilot, because the flight characteristics are unknown. In some cases the plane may enter a spin mode that you may not be able to recover from. Practice spins only in spin-certified aircraft.

Stall/spin relationship
To spin the airplane you must first stall it. Stalls can take place at any airspeed, so it is conceivably possible to spin an airplane at any airspeed. In fact, an aerobatic maneuver known as the snap roll is a high-speed stall/spin, resulting in the plane spinning in the direction the plane is moving. This can be going horizontally, vertically, or straight down and is a very rapid, quick maneuver.

You may reason that if a plane is difficult to get into a spin, it may also be difficult to get out of the spin. While this is not always the case, be certain you know the correct spin entry and recovery procedures for your airplane. The following discussion will be generally applicable, but the plane you are flying may have a unique set of techniques that are documented in the aircraft operations manual.

Spin versus spiral
From the cockpit these two maneuvers can appear very similar; the plane is in a nose-down attitude rotating to the left or right. There is, however, a very large difference between spins and spirals. During a spin the plane is stalled. A spiral is not.

A spiral can be entered from a botched attempt to spin the plane, but a spiral is significantly different in what is aerodynamically taking place. Unlike the spin, the wings are not stalled in a spiral; they are both producing lift. The rolling motion found in a spiral is normally due to aileron and/or rudder control inputs. Another major difference is that the airspeed will be rapidly increasing in a spiral. This can become a dangerous situation. If the plane accelerates to speeds beyond Vne, structural damage could occur.

Recovery from spins and spirals also differ. For a spin you must reduce power on the engine to idle, input full rudder in the direction opposite to the spin, and ease forward on the elevator control to break the stall. To recover from a spiral, you also must reduce engine power to prevent excessive speed buildup, but you will not need full rudder opposite the direction of the spiral’s rotation and you will not want to push the nose of the plane down further through forward elevator control inputs. This would actually result in the plane entering a greater nose-down attitude and gaining even more airspeed. The use of full rudder opposite the direction of the spiral could actually cause excessive yawing and additional controllability problems. Rather, reduce engine power to keep the plane from gaining speed too quickly, level the wings, and ease the nose back to a level flight attitude. Avoid pulling back too sharply on the elevator control; too much elevator could inflict excessive g-forces and result in damage to the aircraft.

Spiral entry will not happen the same way for every airplane. You may accidentally roll the plane into a spiral or find some other unique manner for putting the plane into a spiral. It may be the result of attempting to spin a plane that is reluctant to do so, or simple pilot disorientation. Accordingly, experience is the best teacher for getting a feel for what a spin feels like, as compared to a spiral.

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