IMAC aerobatics performing tail slides

Model Airplane News, May 2000 by Wolanski, Dan

The tail slide is an advanced maneuver in which the plane is flown vertically and allowed to stop. It then slides backward about one fuselage length, swings around its pitch axis, swaps ends and begins to fall nose down, regaining sufficient airspeed to enter the next maneuver.

There are two basic types of tail slides: wheels up and wheels down. During a wheels-up tail slide, the plane is allowed to pitch backward toward the canopy as it descends. During a wheels-down tail slide, the plane pitches forward toward the wheels.

PERFORMING THE TAIL SLIDE

The most important part of a tail slide is the entry. To achieve a tail slide, a true vertical entry is required before the reduction of throttle; otherwise, the plane will slip into a hammerhead, resulting in a zero score for the maneuver in International Miniature Aerobatic Club competition (IMAC). To perform a wheels-up tail slide (Figure 1), fly to the end of the box and increase to full throttle as you pull to vertical (it's easier to look at the top of your plane during this maneuver). Quickly reduce the throttle to idle, and just before the plane stops its vertical ascent, input a small amount of up-elevator. This "cheat" will induce the plane to fall on its back side and perform a wheels-up tail slide. Keep in mind that this "cheat" requires only about 3 degrees of pitch change but is necessary to establish the desired direction of fall. Once the plane has stopped and begins its backward slip, input down-elevator. The down-elevator maintains the direction of fall during the slide. This may seem contradictory, but since the direction of the plane has reversed, so must the elevator input. Figures 3 and 4 demonstrate why opposite elevator direction is necessary during the fall. Allow the plane to "pendulum" back and forth until a straight downline is achieved. The pendulum action about the pitch axis is not a downgrade, so don't worry about trying to stop it.

A wheels-down tail slide (Figure 2) is performed with the same entry as before, but as the upward travel stops, you input down-elevator. As the plane begins to slide backward, up-elevator is applied; this maintains the plane's pivot toward its wheels.

PILOT'S-OPTION TAIL SLIDE

A more popular trend in model aerobatics competition during recent years is the pilot's-option tail slide. This was designed to get pilots away from "cheat" entries by allowing either a wheels-up or -down descent; this also creates a more dramatic slide, This trend seems to be catching on with IMAC, TOC, the Masters and the Pacific Coast Championship (a new, highprofile invitational event). This option seems to be the most popular with the crowd and the pilots and will probably eliminate the need for specific directional slides in the future.

FINAL TIPS

Try not to draw a very tall up-line as you enter the tail slide. As your plane slows because of gravity and drag, you may experience a bit of torque from the prop. This will ruin your vertical up-line and could earn you a zero score. Maintain full throttle and keep the plane's speed up; then chop the throttle to idle while you still have a lot of vertical momentum. This should greatly reduce the torque induced by the prop.

Have fun with the tail slide. Compete with your flying buddies by counting how long you can get it to slide backward. For added fun, try it with smoke. The dramatic effect of your plane falling through a dense cloud of smoke is a definite crowd-pleaser! .