GaRC,

Decathalons, like Cubs, T-crafts and other similar planes all share a couple of common tendencies. The one that causes the most trouble to inexperienced pilots is their tendancy to groundloop.

A groundloop occurs during ground handling (duh...). A short tail and close spaced landing gear on a taildragger are contributing factors. It can happen on take-off or landing, but is more common at take-off.

A typical scenario is the pilot taxi's to the hold position, then advances the throttle to take off. The combo of spiral wash and perhaps other prop effects cause the plane to yaw to the left. The pilot must apply right rudder to counter this quickly, or the plane may begin to roll to the outside of the turn rather rapidly (just topple over on the narrow gear). Depending on the speed at the time, this may result in an embarrassing donut, or an ugly cartwheel.

A few things can be done to reduce this tendancy. First, during the initial roll-out on take-off, hold full up elevator for a moment or 2. This keeps the tail wheel pinned to the ground and gives you rudder authority until you have airspeed for the air rudder to be effective with. Control yaw with rudder stick. Once the plane is moving, the elevator must be relaxed to allow the tail to fly and the plane to gather flying speed, or the plane will pop up, likely stall, and crash.

The other thing is a mechanical tweak to the plane's landing gear. The mains should be toed in a couple degrees. This effectively prevents ground looping. Toed in means that the wheels don't point straight forward, but are each steered towards the nose slightly. If you were to extend a line along each wheel's natural path, they'd cross 10 or 12 feet in front of the plane.

With toed in wheels, when the plane yaws on the ground, the wheel on the outside of the turn is effectively put at a more extreme "angle of attack" to the plane's direction. This tends to slow that wheel and haul the plane back towards on-line. It doesn't eliminate the need to be on the rudder, but it reduces it a bit.

Lastly, super dec's are known to want to land a bit faster than you'd think for a "trainer looking" plane. See what it's stall performance is like at altitude before landing the first time. If it has a tendancy to tip stall violently, (in a stall it suddenly snaps and rolls over instead of simply mushing forward), adding a couple degrees of washout to the wing will help. Washout is twisting the wing such that the tips point down compared to the rest of the wing by about 1-2 degrees. This can be done by holding the tip and root of the wing, flexing it in the desired direction, and then ironing or heat gunning the resulting wrinkles from the covering. Allow to cool and release. The covering will hold a bit of washout with no real trouble. A little bit goes a long way. This aerodynamic feature is what made the Spitfire such a formidable fighter in it's day. Without washout, that elliptical wing would have made the Spit a snappy bugger of a plane.

J