Koolhoven FK-53


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Construction

Koolhoven FK53 "Junior" 1937 lightplane designed by Juste van Hattum who also drew the plans for a 1:20 scale model intended to encourage beginners to model building.

This example is based on the original drawings but extensive changes were made for the sake of weight-saving and damage-resistance.

The full sized prototypes flew but the model has only achieved some short hops in spite of light construction.

September 2007 - maiden flight attempt.

The rubber motor (4,1mm Tan I in a 40 cm loop) is wound to 700 turns using a winding-mechanism that speeds up the laborious process and is fitted with a counter to keep track of the turns - no small matter with heavy rubber and a delicate model !



After a long struggle it dawned on me what had gone wrong in the design of the model and proper performance started to emerge. Books written by experienced modellers helped me along! If the old hands are right, and they usually are, then the spiral dives that now threaten every flight can be blamed on a vertical tail that is too large – and so a smaller one has been built.



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