The sure way to a safe landing

 From the  catalogue of questions for the PPL

              - after a flight at great height

                there is the danger of misjudging the height and holding off to high,

              - after a hard landing

                a thorough inspection of our aircraft is recommended.    

Such and similar questions should be unnecessary, since it is possible to land gliders regularly in safe manner. Wehere, a young had to be brought to a hospital after a hard landing are preventable. This accident happened while I was towing for Oerlinghausen. Even though I presented whenever I could the “Landing machine” and pointed out that turning at very low height is not a good idea and sideslips should be used instead.

The landing machine

The landing machine is not any other as a horizon of your landing field.

picture 1. Horizon (M) of the Airfield

The concept of “the landing machine” is already 30 years old but still quite unknown. The name was introduced 4 years ago by a group of course participants in   Oerlinghausen and is established there. In Serres we are applying it now too. It  would be highly desirable if gliding instructors would use this method to assure safe landings of their pupils. A copy of “the Landing machine” belongs on the knee board of every gliding instructor.

picture 2. The  Landing machine: GP- Glide Path,  DH - Decision Hight, L- Hold-off, PC - Point of Contact, LS - Line of Sight, HL - Horizon of the Landing field, M - Marking,   WL- Wurm Landing, CL- Center Line, GP- Glide Path, RWY- Runway.

An ordinary  carton is cut in such a way and folded so that it fits the kneeboard. Also a string representing the horizontal line of the landing platform belongs to it. The attitudes of the aircraft can be presented by a pen or such. A schematic drawing with runway augmenting the above will make it easy to illustrate and simulate landing attitudes. In a schoolroom setting the usefulness of the Landing machine can be expanded by drawings and other means so that every question about   landing safely can be answered. The most important point is the Marking (M) on the canopy in the line of sight to the horiz on at the end of the landing field. Within a short time the pupil will control the correct attitude for a landing  in a routine manner. The landing is the high point of every flight and has nothing to do with luck or One should not talk about a successful landing rather a executed landing.

The method of the Landing machine can be demonstrated on a  ASK-21.

Every  Landing begins before the take-off. After the trainee and the instructor are positioned in the cockpit, the cockpit check takes place.

picture 3. ASK 21  before take-off  - main wheel and front wheel contact the ground.

picture 4.  ASK 21  in preparation for a landing  - main wheel and tail wheel contact the ground.

  tail wheel contact the ground and the wings hold horizontal. The trainee can now effect a marking (M) on the canopy or instrument panel in the line of sight to the horizon of the landing field. This mark is the important addition to assist in landing.  In preparation for a landing the aircraft has to be brought into landing attitude by having the main wheel and

picture 5.  Landing : GP- descent,  LS - Line of sight,  M - Mark, L- Hold-off, WL- Line of sight, HL-  Horizon of the landing field. 

 After the flight You enter the circuit which leads finally to the final glide. The glide path can be fairly steep (GP). The line of sight (LS) shows the point of contact (PC) at  the landing (T). At a height between 2 and 0.5 m the hold-off begins and the pilot pulls the stick gradually towards himself to  bring the line of sight, the cockpit marking and end of the runway together. This attitude is rigorously maintained till the aircraft the ground. (Two point landing.) In the end the control-stick will have been pulled all the way back for a minimum energy landing. This landing approach will eliminate all the common landing errors. For a hold-off landing it is only necessary to hold the cockpit marking above the end of the runway point.

picture 6.  Wurm Landing (WL): descent (M on the HA), hold-off (LS), landing.

Cross wind on final

The landing described previously was under ideal conditions. Often cross winds are encountered without correction.

 picture 7. Lateral displacement by cross wind.

Directionslip

In order to avoid the lateral displacement we apply the directional slip. After turning into final we introduce aileron to lower the wing into the wind and apply rudder to maintain the landing direction. The wing angle will have to correspond to the strength of the wind such that no lateral displacement takes place.(Correction only with aileron.)

picture 8. Directionslip.

Sideslip

In case of a less than optimal circuit geometry, turning into final, could still be off course and require adjustment. Instead of turning close to the ground the sideslip. Can displace the aircraft laterally while maintrain the landing direction through rudder.

                       R                                                       L

picture 9. Sideslip:  R – to the writhe, L -  to the left.

Roapbreak - right after take-off: bring attitude of aircraft into landing by bringing cockpit marking and end of runway line together. Again the sideslip will allow lateral Displacement as necessary.

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Adalbert Dombrowski,

Auf dem Graben 8

37297 Berkatal / Germany

Tel-Fax: +49 (0) 5652 3937

 mobile  +49(0)1753318882

dombrowskijaw@compuserve.de

http://www.landemaschine.de