Friday, March 11, 2016

Flying a Tailwheel or Conventional Gear Aircraft

Here is a short document I produced years ago for my tailwheel students. This document does not include extreme detail of the fine art of flying tail-draggers, rather an outline.

by

Jim Skibinski











FAR 61.31 No person may operate a tail wheel aircraft unless that pilot has received instruction in normal and crosswind takeoffs and landings, wheel landings. This endorsement is not required if the pilot has logged PIC flight time in a tail wheel aircraft prior to April 15, 1991.

Stability of tail wheel and tricycle gear aircraft

1. TW Center of gravity located behind the gear which is the stabilizing force
            a. Due to basic physics, stability is based upon C of G leading stabilizing force. 
            b. Landing with side drift can initiate a loss of control called a “Ground Loop”
            c. Landing w/ crosswinds compounds the instability due to weather vaning
            d. Tri-gear are stable due to C of G located forward of mains.
            e. Tri-gear landing with side drift will correct itself (to a degree)
            b. Tri-gear landing w/ drift cancels out any weather vaning

3. Rotating slipstream
    Torque (difference in models)
    P Factor
    Gyroscopic precession
            a. Adversely affects TW when tail is raised

4. Runway surfaces
            a. Grass, wet or dry
            b. Gravel or other “soft” surface
            c. Pavement
            d. Length, width, obstructions

5. Aircraft differences
            a. Gear spread
            b. Tail length
            c. Forward visibility
            d. Gear shock absorber design (steel, bungee)
            e. Weather vaning tendency – surface area aft of C of G
            d. Angular momentum (amount of mass fwd of gear)
                Heavy engine or long nose
f. Nose over tendency
    C of G located near mains helps improve control but increases
    Nose over tendency

Preflight 

1. Tire pressure (low pressure can increase nose over tendency)
2. Tail wheel condition and orientation
3. Examine tail surfaces carefully, (proximity to ground)
4. Examine brake condition – wear, leaks, ice, mud etc.

Engine Start

1. Brakes held
2. Hand on starter, hand on throttle, hold elevator back
    Obviously this could be a handful

Taxiing

1. Brake Check – must be performed
2. Taxi speed – SLOW
            a. Slow speeds allow more positive control
            b. Heavy braking at slow speeds will not likely end in a nose over
            c. S turns may be required
            d. Use only min pwr to taxi – prevent excessive use of brakes resulting in a
                Locked brake during the take-off roll
3.  Flight control positioning in any amount of wind
            a. Yoke back – taxi into the wind
            b. Yoke forward – taxi with the wind
            c. Crosswind or into quartering wind – ailerons turn into
            d. Crosswind or Away from a quartering wind – ailerons turn away
                                “Dive away - Climb into”
4. Rudder use and authority
            a. Recovery from a turn must be initiated sooner than a tricycle gear
            b. Avoid over control due to excessive brake use
            c. Small radius turns can be accomplished by applying brake and allowing the
                tailwheel to unlock and swivel. To engage steering again is a matter of stepping
                on the opposite brake and applying opposite rudder.
            d. Do not lock brake and pivot around main gear, imposes much strain on gear
            e. Small radius turns can also be produced by applying full rudder, a small burst
                of power and moving the elevator slightly forward to unload the tailwheel.
                BE VERY CAUTIOUS WITH THIS MANEUVER  





Normal Take-off

1. Elevator back, advance throttle slowly. As speed increases, move yoke forward
    transferring steering from the tailwheel solely to the rudder.
    a. As power is brought up, the P-factor, torque and slipstream forces take effect.
    b. As the tail comes up, gyroscopic force takes effect, P-factor neutralizes,
        torque and slipstream are still present.
    c. Torque is less prevalent with the tail down because the plane of orientation
        is not perpendicular to the ground. Torque loads the left main. (more friction)
2. Tail up, speed increasing, elevator control moves to neutral as speed increases.
3. Maintain directional control by correcting deviations and maintaining centerline by
    quick, positive application of rudder. Apply rudder and then get off of it. This is a
    good technique beginners can use. Over time rudder control will be smoother
    and more controlled.
4. When flying speed is attained – simply apply slight aft elevator pressure and fly off.






Short Field Take-off 

1. Line up the airplane on the runway and let it roll forward just enough to center
    the tailwheel
2. Hold the airplane with the brakes, and with the stick back, gradually apply full power.
3. Release the brakes and as speed picks up let the elevator control streamline itself.
    Steer the airplane to hold it straight.
4. If necessary, apply slight forward elevator control to raise the tail 4 to 6 inches. In
    some airplanes, the tail may rise of its own accord without control input.
5. Allow the aircraft to fly itself off in this attitude.

Soft Field Take-off

NOTE:  In departing a soft field, it is important that the tail not be raised in order to
Prevent the airplane from nosing over. The tail should be held down until lift off.
Be careful of using excessive elevator resulting in leaving the ground is an excessive
nose high attitude, possibly resulting in a stall close to the ground.

1. Lower the flaps (if equipped) as recommended by flight manual
2. Gradually apply full power and insure take-off is straight.
3. Maintain the elevator control slightly aft of neutral to keep the tail down. Should
    both mains bog down, it may be necessary to apply full aft elevator control. During
    taxi if both mains get bogged down or taxiing is impossible, rapid alternating   
    application of the rudder may loosen the wheels.
4.  As the airplane approaches flying speed, back elevator pressure should be relaxed
     in preparation for take-off.
5. When the airplane leaves the ground, it is leveled of until it accelerates to the best
    rate of climb or best angle speed (Vy) (Vx).

Crosswind Take-off 

1. Use aileron to keep the windward wing down.
2. Delay raising the tail to ensure enough airspeed for positive rudder control and to
    overcome weather cocking caused by the crosswind.
3. Make the departure from the ground a positive one by raising the tail slightly
    higher (prevents pre-mature lift off) and allowing acceleration to a higher than
    than normal speed before lift-off.

Three Point Landing 

1. The approach is no different than a tricycle geared aircraft
2. The airplane is gradually flared out close to the ground
3. Keep the aircraft flying as long as possible. Continually increasing back elevator.
4. Aircraft will finally stall, hopefully only a foot or two above the ground.
5. The stick must be held full back during roll-out.
6. Brakes should not be applied unless needed, and then only sparingly and with a
    pumping motion.




Wheel Landing 

1. Normal approach profile and airspeeds
2. In the early part of the flare-out, let the main wheels contact the ground with minimum
    downward velocity. It may be advisable to carry some power to the touchdown point.
3. Unload the wing by applying just enough forward elevator to keep the tail up during
    the landing roll. Continue until full forward elevator is achieved… the tail will descend
    upon its own accord.
4. Once the tail has lowered to the ground, apply full back elevator to keep the tail wheel
    on the ground.

Short Field Landings 

Specified airspeed is the key to this approach – Keep it in check. The approach speed is typically slower than normal approach speed resulting in higher drag associated with a higher angle of attack. Therefore, in most cases this will be a power-on approach. The landing will be a three point since it ensures the lowest possible speed at touchdown. As soon as the aircraft is rolling on the ground, full back elevator is applied and brakes can be pumped using an alternating sequence. Should the plane show signs of wanting to nose over, a blast of throttle will prevent it. If equipped with flaps, raise them as soon as the aircraft is on the ground transferring more weight to the wheels.  

Soft Field Landings 

The soft field landing is performed like the short field version except that the application
Of brakes is omitted. Some power is generally carried because it allows the airplane to be flown at its slowest speed. Also, flaps should stay extended until the aircraft comes to a
stop. Once again, if the nose wants to go over, don’t hesitate to use a blast of throttle to
force the tail down.

The Bounce 

A bounce can result when an aircraft is dropped in with excessive airspeed. A bounce can also result from attempting a three point landing and not continuing to increase elevator back pressure through the landing sequence. As the aircraft touches down on the mains, due to the C of G behind the mains, the tail will rotate downward effectively increasing the angle of attack. With excessive speed and increased AOA (more lift) the aircraft will rise up into the air with a high angle of attack and decreasing airspeed. Effectively the aircraft will be at a much higher altitude in a stalled condition. Doing nothing at this point is VERY bad… the ensuing drop from this event will get your attention. Most bounces are mild and can be solved by holding the elevator back and riding through the bounce.

Recovery from a severe bounce is a follows:
1. Application of full throttle for an immediate go-around
2. Let the airplane descend and flare again when close to the ground. This will be   
    accomplished safely only if sufficient air speed exists, probably because the original
    approach and flare were attempted at excessive speed.
3. If insufficient air speed exists for item 2. above, the pilot may apply sufficient power
    to prevent a stall, allow the airplane to descend and flare again for a landing.

Crosswind Landings  

For better control of drift during touchdown, use the wing down method while performing a wheel landing. Same procedures apply for drift control… windward wing down using opposite rudder to maintain course. Also, use the same procedure for wheel landings. At touchdown, forward elevator to unload wing while maintaining aileron into the wind. Aileron increases as airspeed decreases. As the tail is coming down, the aileron control will be full into the wind and elevator control full forward. As the tail settles, keep aileron into the wind and apply full aft elevator.

For lighter wind conditions, a three point landing can be used. 

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