HP-18 Crank
Udo Rumpf

(Another alternative)


Crank Modification.

The existing crank can be modified with the same parts and except for a drill press and a tap no expensive tools are necessary. In the drawing where I show the crank being shortened, I have in the beginning bolted the two pieces together only after I was happy with the change did I weld it. The length of the crank handle and arm is adequate and it will help to get in and out of the cockpit with much more ease, especially in case of an emergency type exit. Also persons with larger thigh muscles have more room.


The rack and pinion drive.

After watching a HP18 landing with resulting damage in an adjoining corn field, it turned out to be the pinion drive that failed. When I got my HP18, one of the first things I changed was that drive. It is a bit more complicated but it is well worth it The third attach point is new for me but not the roller and it will be a stabilizing addition. As I remember, a lot of wear on the two mounting holes, caused by the cranking unit as it wiggle from side to side as well as flexing the cockpit railing. Attention should be paid to the push rod to make sure it rides freely in its full range through the rack and pinion drive.