Update #22

Bending the 601 Leading Edge Skins!

A 15 person-job but it produces perfect bends!

As we finish the CH-701, we continue to work on the 601. We have one wing assembled and the other ready to clecoe together. A difficult piece to fabricate is the leading edge skin. Some builders simply lay the skin on and bend it around as they drill and clecoe. This often leaves gaps as the skin doesn't exactly fit the ribs. On some parts of the airplane a small mismatch would not be critical but the wing, and especially the leading edge, are very critical. Any deviation from the optimal wing shape will affect drag, airstream separation, stall, speed, and controlability. Some aircraft are so intolerant of airfoil changes that bugs smashed on the leading edge adversly affect performance.

	We are fortunate to receive the expertise and experience of Bill Crib and Bill Jr. They are building two CH-601s and helping with two others as well as mentoring in our project. In early February they brought their leading edge skin bending jig and showed us how they had solved this problem.
Here, Bill Sr. and Mr. Smith start to set up the fixture that will bend the leading edge skin.
	The leading edge skins are about 11 feet long so the jig has to be at least that long. It consists of 6 supports for a 12 foot long steel bar. The supports are bolted into the table tops
The other part of the fixture is the fulcrum of 6 large levers which force a shape tightly over the bar, squeezing the aluminum skin between them.
	Though large, the fixture is very portable. Mr. Smith and Mr. Crib assembled and disassembled it within 30 minutes.

	Simplicity itself, the 2 2x4s fit exactly around the rod forcing the skin to wrap itself tightly around the bend. Aluminum has a 'spring back' when it is bent. Typically, it must be bent 8 to 10 degrees further than intended and it will 'spring back' to the proper bend.
The large vertical bars are fulcrums that hold down 2 x 6 levers that bear down on the wing skins.
	We had to round up some volunteers to sit on the tabletop and hold it down as the skins were being bent.
Flat Skin
	Bending skin
Bent skin.
	Here the leading edge can be seen easily wrapping around the nose ribs. This method of bending two leading edges ensures that the intended airfoil will be produced, and very importantly, both wings will have an identical shape.