faces must produce a downward force to raise the nose. This negative lift (expressed in pounds) effectively adds additional weight to the airplane, requiring the wing to produce greater lift to enable flight. For a given angle of attack, this may only be accomplished by accelerating more air over the upper curvature of the wing to further reduce pressure. This requires a longer takeoff roll. Also, unless the nosewheel can be immediately raised off the ground by the application of power, its tendency will be to traverse the contours of the runway surface, varying the angle of attack of the wing and retarding its effectiveness. This can only serve to increase the departure roll. Conversely, Figure 2 depicts a taildragger accelerating on the departure roll. The pilot must now raise the tail to position the wing at the maximum lifting angle. As Figure 1 clearly illustrates, this generates positive lift on the horizontal tail surfaces. The upward force produced effectively reduces the weight of the airplane by contributing to the overall vertical lift component. Consequently, less forward speed is required (read less ground roll) to become airborne.

Initially, the novice tailwheel pilot struggles greatly to master this new art. The two villains attempting to foil the unsuspecting pilot are the wind

and the location of the airplane's center of gravity with respect to main landing gear.

One soon discovers that the tailwheel airplane, not unlike a floatplane in the displacement mode, makes an excellent weathervane while taxiing. Depending upon wind direction and velocity, the airplane always wishes to "weathercock" into the wind. For this reason, upwind turns are accomplished quite easily. Downwind turns, on the other hand, can prove extremely difficult, if not impossible. Moreover, a downwind turn may require a substantial application of power to aid with rudder effectiveness, combined with hefty differential braking. Attempting a downwind turn while taxiing could prove impossible, forcing the pilot to exit the cockpit and physically move the airplane to the desired heading.

A sharp pilot is "wind conscious" and seeks to take advantage of the upwind turning tendencies by planning turns toward the upward direction. This same airman is the individual who knows to "ramp" the airplane facing into the wind as opposed to haphazardly placing it on the apron.

A tailwheel pilot also needs to be cognizant of wind direction and velocity at the start of the takeoff roll. (These concepts pertain to all pilots.)

A left crosswind will serve to compound the "left turning tendencies" already inherent in airplane design and will require additional right rudder application. A right crosswind may minimize or potentially eliminate the "left turning tendencies" requiring less right rudder input. The "left turning tendencies" inherent with a clockwise rotating crankshaft includes torque, asymmetric thrust (P-factor), slipstream spiral, and gyroscopic precession. Expect the taildragger to have a more pronounced left yaw tendency when power is applied. P-factor exists because rotational velocity of the propeller is more significant when placed at a greater angle of attack by virtue of the airplane's three point attitude as the airplane moves forward. Moreover, when the tail is raised as the airplane accelerates down the runway, gyroscopic precession will induce an additional left yawing moment. Be sure to "trap" the nose with the application of right rudder to preserve directional control.

The weathervaning propensity so apparent with tailwheel airplanes exists due to the greater amount of surface area and longer moment arm (upon which the winds act) that is present between the main wheels (pivot point) and the tailwheel. Also, a swiveling type tailwheel, as opposed to the locking style, will contribute to the ease in which the tail will move. The tricycle gear airplane has less surface area and a relatively short moment arm existing between the main wheels and the nose wheel. Certainly, the proximate location of the center of gravity and the weight of the engine. and its accessories placed nearly on top of the nosewheel strut contributes greatly to eliminating nosewheel displacement during gusty wind conditions. However, the wind is only one reason the tailwheel pilot struggles to preserve directional control. The second reason involves the location of the center of gravity with respect to the main landing gear. Interestingly, if the CG was located ahead of the main landing gear our taildragger would require a nose wheel conversion, because the airplane would now

be resting on its nose.

Recall from earlier studies that the center of gravity of an airplane is the point at which all weight is assumed to be concentrated. Also, recall that an object in motion has momentum and its inertia will continue to move along its original path should the object become displaced. Momentum acts through the center of gravity. Figure 3 portrays a tailwheel airplane in motion, traveling along a straight line. Momentum is depicted moving through the center of gravity. Figure 4 shows the aircraft losing directional control to the left. Due to inertia, the momentum of the CG continues to move along its original path which is straight down the runway. It can be seen that momentum is now applying a force to the outside wheel of the turn. This force will begin to decrease the airplane's turn radius, and, as the radius of the turn. decreases, its moment of inertia will begin to increase the rate at which the airplane turns. In other words, as directional control is lost, momentum acting through the CG will apply a force to the outside wheel of the turn and cause the airplane to turn tighter and faster. This helps explain why the tailwheel airplane is intolerant of poor technique. A successful outcome demands that an attentive pilot properly use rudder and aileron inputs to preserve directional control and be able to touchdown with zero drift when landing. Figures 5 and 6 help explain why tricycle gear airplanes are so forgiving of inferior technique. When the "trike" begins to lose directional control, momentum acting through the center of gravity has a tendency to realign the airplane with the runway by pulling on the inside wheel. This explains why the tricycle gear airplane is so inherently stable. It also proves that operating a taildragger can be more challenging and demanding, requiring the strict attention of the pilot at all times.

When starting a taildragger, particularly the lighter weight models, it is a good idea to apply aft stick to prevent the tail from rising. For heavier aircraft, such as the Cessna 180 or Maule M-6, this is not as critical.

After minimum "temps" are real

Figure 3 Tailwheel airplane in motion traveling along a straight line. Momentum is depicted moving through the center of gravity.

Figure 4 Shows the tailwheel airplane losing directional control and rotating to the left.

Figure 5 Tricycle gear airplane in mo

tion traveling a straight line. Momentum is depicted moving through the center of gravity.

ized, throttle is applied to begin taxiing the airplane. Place the stick in the aft position and only apply enough power to allow the airplane to begin to creep forward. Use of excessive RPM on a relatively cold engine is poor technique and can easily damage a powerplant as the pistons are forced into a cylinder choke that has not yet reached a normal operating cylinder head temperature. Additionally, the majority of conventional gear airplanes suffer from poor over the nose visibility, and require a cautious "eyes out of the cockpit" slow taxiing procedure. Learn to taxi while executing gentle S-turns to enhance your scan and to hopefully avoid an incursion.

Remember to position the flight controls properly with respect to headwind and tailwind components. An excellent initial wind awareness exercise is to find a large unobstructed area on the apron and to taxi in left and right 360 degree circles. As the pilot circles, the relative direction of the wind to the aircraft is constantly changing, requiring the pilot be able to reposition the ailerons and elevator appropriately.

After completing the pre-takeoff checklist, taxi onto the runway centerline. Pay particular attention to the attitude of the airplane with respect to a point on the horizon. This is the same attitude the pilot needs to visually ac

quire to be able to execute a three point landing. With aileron placed into the wind and the stick placed in the full aft position, begin to smoothly apply maximum allowable power. Attributable to slipstream spiral and P-factor, the aircraft will begin to yaw to the left. Torque further compounds the left yaw as its "rolling moment" applies a downward force to the left main landing gear, increasing the frictional resistance of the left tire. Remember that surface wind may serve to increase or reduce the yaw tendency. Apply appropriate rudder as necessary to preserve directional control. As the airplane accelerates, decrease upwind aileron, release the elevator back pressure, and begin to apply slight forward stick pressure to raise the tail and poise the wing for lift off. As the tail rises, be sure to "trap" the airplane in the lift off attitude by reapplying slight back pressure on the stick. Too much forward stick pressure will create a negative angle of attack forcing the main wheels into the runway, which lengthens the take off distance. Also, as the tail begins to rise, the effect of gyroscopic precession will make itself known and the aircraft will wish to yaw left. Apply right rudder as necessary to maintain directional control. With the wing poised for lift off simply allow the aircraft to fly itself off the runway. Accelerate to best rate or best angle of climb, as necessary.

Fundamentally, there are two types of landings to be mastered when operating a taildragger: the three point landing and the "wheel" landing. The latter type is not meant to imply that a three point landing is not on the wheels. I would hope all landings (in a land plane) are on the wheels. It's just that a wheel landing touches down on the main landing gear first, and the

pilot then transitions to the three point attitude as forward speed dissipates. The concept of the three point landing requires the pilot to touch down on all three wheels simultaneously, or the tailwheel touching slightly before the main landing gear. This is historically referred to as the "full stall" landing. It is simply the attitude at which the aircraft normally rests when on the ground. Visually, it is precisely the attitude (as viewed from cockpit) revealed before the start of the takeoff roll. The three point attitude nearly approaches the critical angle of attack and consequently allows the airplane to touch down at near minimum speed.

The key to successful three point landings is to touch down without excessive speed and with zero drift on all three wheels concurrently or tailwheel slightly first. Of course, proper crosswind technique must always be strictly adhered to. Recall that the CG is located aft of the main landing gear. If, when attempting a three point landing, the pilot impacts the runway with the main landing gear first, the CG will cause the tail to become lower, which increases the wings' angle to attack. The result is increased lift and the airplane once again becomes airborne. It is important to develop visual cues through practice to learn the proper three point attitude. When the pilot perceives the aircraft is about to make contact with the runway, continue to apply aft stick in an effort to prevent the aircraft from touching down. "Hold it off as long as possible" is the appropriate phrase. When the aircraft touches down in the proper three point attitude, gracefully apply full aft stick to enhance controllability. Continue to preserve directional control with the rudder pedals. Maintain aileron into the wind as necessary.

Remember that tricycle gear airplanes have the CG positioned ahead of the main landing gear. Upon touchdown, when the main landing gear impacts the runway, the nose is forced to become lower, decreasing the wings angle of attack. Consequently, tricycle gear airplanes don't exhibit the same tendency to bounce, unless it is pilot induced.

It is said the wheel landing is generally utilized during gusty wind conditions to gain more controllability from the primary control surfaces. The slightly greater approach speed used for wheel landings does indeed allow for a more "crisp" control effectiveness. However, controllability is usually compromised by wind gusts constantly displacing the aircraft. Successful wheel landings demand a touchdown that occurs with a near zero sink rate, and performing them when turbulent can be most challenging. One method of decreasing the form drag (upon which the wind gusts will act) to better enhance controllability is the use zero or minimal flap settings. Wheel landings can be more difficult to perform than the three point landing. The wheel landing is accomplished by literally flying down the runway and rolling the main wheels onto the surface. This faster touchdown speed results in a longer landing rollout and requires a greater usable runway distance. Remembering the taildragger's tendency to bounce because of CG location when landing main. wheels first, it is important to touchdown with minimum or zero sink rate and then to smoothly apply slight forward stick pressure to ensure the wheels remain on the runway. As forward speed dissipates, fly the tail down by gently applying back pressure. Once the tailwheel is on the runway, apply full aft stick, use aileron into wind as necessary to aid in holding the upwind wing down, and rudder pedals to maintain directional control. One key to successful wheel landings is to carry a small amount of power until touchdown occurs, then apply the slight forward stick pressure, and smoothly reduce the throttle to idle. When easing the tail down to the runway, be watchful of gyroscopic precession now wishing to cause a slight right yawing tendency.

Additionally, when executing a wheel landing, as the touchdown occurs, there may be a slight nose down pitching moment. This is caused by the frictional resistance of the tires as they "spool up" from zero to touch down speed. The pilot must

delicately balance this nose down moment with that of the CG induced tail low moment.

A common fear of new tailwheel pilots executing wheel landings is that too much forward stick pressure will result in a propeller strike. This is highly unlikely and would probably require inappropriate use of brakes to force the aircraft onto its nose.

Throughout tailwheel transition training, should the pilot perceive the aircraft may be losing directional control, it is important to understand that simply stopping the yawing moment with appropriate opposite rudder will serve to stop the ensuing loss of directional control. Many loss of directional control problems are compounded by pilots attempting to not only stop the yaw, but by applying additional correction in an attempt to return the aircraft to its original position. This usually results in over controlling. Simply stop the yaw movement and resist the temptation to apply additional correction. In time, with experience, you will acquire the skill to expertly replace the aircraft to its pre-displaced position.

Maximum performance takeoffs and landings, such as short field and soft field, are procedurally no different than those executed in a tricycle gear airplane. When flying a taildragger, one common technique for soft field

situations is to initially raise the tail slightly to minimize the frictional resistance of the tail wheel. Another acceptable method is to allow the aircraft to become airborne in the three point attitude. Short field departures may be executed in the same manner. The pilot then accelerates to Vy or Vx, a appropriate. Generally, most short and soft field arrivals are accomplished with three point landings, allowing for touchdown at the slowest possible speed.

Lastly, if one wishes to tackle the tailwheel and place themselves on the road to becoming a more accomplished airman, then finding a competent instructor to aid you in developing the art of taildragging will place you on the proper path. Certainly, if one wishes to fly some of the most fun airplanes ever manufactured, you need to give it a try. The skills acquired during training may open the door to a plethora of available tailwheel airplanes, such as antiques, classics, homebuilts, warbirds, and biplanes. Chances are your training would most likely be accomplished in an antique or classic. That alone is worth the price of admission!

Bob Hill is an Aviation Safety Inspector at the Nashville (TN) Flight Standards District Office.