Even if you never want to take off or land at a turf runway in your tricycle gear airplane, the Soft Field Takeoff is a great exercise to refine your technique and re-build confidence. In addition, it is fun!
The Soft Field Takeoff involves a balancing act requiring precise inputs in pitch and rudder. Pitch is constantly changing, from the moment the nose wheel starts lifting, until a firm climb is established. If you keep nose-up elevator too long during the takeoff roll, the tail will likely hit the ground, but if you let go too much, the nose wheel will resettle to the ground. Once lifted off, the down-pitch is required to stay in ground effect until sufficient airspeed as been developed. All the while, left-turning tendencies are constantly changing and will require varying amounts of rudder input to stay centered on, and then above the runway.
The goals of the Soft Field takeoff are:
- Minimize the plowing resistance of the nose wheel into the soft ground by raising it off the ground as soon as elevator authority allows
- Get off the dragging soft field at the lowest possible airspeed, making use of flaps and ground effect to allow the airplane to fly at a lower airspeed and reduce induced drag to accelerate to safe flying speed
As a rule of thumb, when you fly within one wing span off the surface, you are taking advantage of ground effect.
For your check ride, make sure you taxi onto the runway with minimal breaking, yoke or stick fully aft (to reduce nose wheel weight) and make shallow turns.
You don’t have to do this check ride theater if you just want the rust-shaker benefits. In fact, if you have a long runway and you are the only one in the pattern, you can do this maneuver from a stop-and-go. Once stopped on the runway center line and after normal pre-takeoff checks and configuration, do this:
- Start with POH recommended flaps (typically: ~25°)
- Yoke or stick full aft
- Slowly advance throttle to full. It may be helpful to pause the advance at 60% or so before going full, to confirm you have the right amount of right rudder and yoke/stick back pressure.
- Once nose wheel is off the ground, vary yoke/stick back pressure to balance a constant pitch and avoid the tail hitting the runway surface
- When the main gear lifts off, start to reduce back pressure and eventually push the yoke/stick forward to maintain about 1/2 wing span above the runway. All the while, stay above the runway center line using rudder and perhaps some ailerons.
- Once reaching safe flying speed (at least Vx), start a climb. If you have enough room, in some airplanes it may be advantageous to accelerate longer in ground effect. In others, you may need to clean up before you can get to Vy.
- Once positive climb is established, flaps and gear can be incrementally retracted while maintaining Vx or Vy. Important: no configuration changes while accelerating in ground effect!
Note: If you have enough room, in some airplanes it may be advantageous to accelerate longer in ground effect. In others, you may need to clean up before you can get to Vy and you will need to start a climb somewhere between Vx and Vy, clean up the configuration, and pitch for Vy once above any obstacles.