 Wing Rising After Touchdown Chapter Summary  Hard Landing In all the proper landing techniques except the soft fi eld, the  nose is lowered after the front wheel touches to put a negative  AOA on the wing and keep the WSC aircraft on the ground.  However, there may be instances when landing in a crosswind  that a wing wants to rise during the after-landing roll. This  may occur whether or not there is a loss of directional control  depending on the amount of crosswind and the degree of  corrective action. Any time an aircraft is rolling on the ground in a crosswind  condition, the upwind wing is receiving a greater force  from the wind than the downwind wing. This causes a lift  differential. Also, as the upwind wing rises, there is an  increase in the AOA which increases lift on the upwind wing  rolling the aircraft downwind. When the effects of these two factors are great enough, the  upwind wing may rise even though directional control is  maintained. If no correction is applied, it is possible that the  upwind wing rises sufficiently to cause the downwind wing  to strike the ground. In a crosswind, the windward wing should be lowered  slightly as a preventive measure to avoid it from lifting. But  in the event a wing starts to rise during the landing roll, the  pilot should immediately lower the nose while lowering the  wing. The wing should be lowered as soon as possible. The  further a wing is allowed to rise before taking corrective  action, the more wing surface is exposed to the force of the  crosswind. When the aircraft contacts the ground during landings, its  vertical speed is instantly reduced to zero. Unless provisions  are made to slow this vertical speed and cushion the impact  of touchdown, the force of contact with the ground may be  so great it could cause structural damage to the aircraft. The purpose of pneumatic tires, shock-absorbing landing  gears, and other devices is to cushion the impact and to  increase the time in which the aircraft’s vertical descent is  stopped. The importance of this cushion may be understood  from the computation that a 6-inch free fall on landing is  roughly equal to a descent of 340 feet per minute. Within a  fraction of a second, the aircraft must be slowed from this  rate of vertical descent to zero without damage. During this time, the landing gear together with some aid from  the lift of the wings must supply whatever force is needed  to counteract the force of the aircraft’s inertia and weight.  The lift decreases rapidly as the aircraft’s forward speed is  decreased and the force on the landing gear increases by the  impact of touchdown. When the descent stops, the lift is  almost zero leaving only the landing gear to carry both aircraft  weight and inertia force. The load imposed at the instant  of touchdown may easily be three or four times the actual  weight of the aircraft, depending on the severity of contact.  After a hard landing, the WSC carriage and wing should be  inspected by qualified personnel for airworthiness. All landings should consist of evaluating the wind and  conditions so a proper base and final are planned to land at  or beyond the intended point. After the final approach to the  runway, the roundout is started about 10 to 15 feet high and  is a gradual descent until the rear wheels are inches above  the surface. The rotation is continued as the speed bleeds off  to maintain the wheels one to two inches above the runway  until minimum controlled airspeed at which the WSC aircraft  settles to the ground. A roundout that is too fast, or ballooning  where altitude is gained during the landing, is a common  mistake and should be avoided. The best landing technique for light wind conditions is with  power brought to idle during the downwind leg of the pattern  before the turn to base. Proficiency in power-off accuracy  landings with 90° turns, 180° turns, 360° turns, and circling  from above are all important safety procedures.  Crosswinds or landing in turbulence requires more energy,  including power-on approaches with higher airspeeds.  In these conditions, the WSC aircraft can be fl own into  the ground above the stall speed. Go-arounds are normal  procedures and should be performed if there is any question  as to the successful outcome of any landing. 11-30