Davis Aero Parts,Inc.
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Research and Development


 

By Benny Davis
I’ve been building wood wings for forty years. When someone came out with wood leading edges I tried it and became a believer immediately.  The one thing I didn’t agree with was one size fits all. The top wing on Pitts and Eagle Bi-planes have a different air foil than the bottom wing.  I also reasoned that  “If Carbon Fiber is so great, why wouldn’t  it be better than wood?”  I had a friend hot wire a mold with his C.N.C. cutter exactly the shape of the bottom wing leading edge and the top wing leading edge; then made some Carbon Fiber leading edges using three layers of 10 oz Carbon Fiber. Then I reasoned, “ The race car people are using Carbon- Kevlar-Carbon in combination for explosion protection, why not for leading edges?” After building a few sets, I began wondering, “How do I find out which process is superior?” So my mind started mentally building a testing  device. On July 13, 2014 we had a joint meeting  of EAA Chapter 409 and EAA Chapter 1143. In the week preceding this meeting I gathered  some scrap metal and built this device to batter three sample leading edges to destruction.  Here’s a video of the results.
The set up was a metal basket allowed to free fall from a 90 degree angle with weight added incrementally one pound at a time until the leading edge was destroyed.
Aluminum 1st dent 1 lb 2nd Dent Each add lb Final
Destruction 5 lbs
Wood 1st crack 3 lbs 2nd Crack 5 lbs Final
Destruction 10 lbs
Carbon/Kevlar 1st crack 5 lbs 2nd Crack 8 lbs Unable to destroy @ 25 lbs

I’ve been building wood wings for forty years. When someone came out with wood leading edges I tried it and became a believer immediately.  The one thing I didn’t agree with was one size fits all. The top wing on Pitts and Eagle Bi-planes have a different air foil than the bottom wing.  I also reasoned that  “If Carbon Fiber is so great, why wouldn’t  it be better than wood?”  I had a friend hot wire a mold with his C.N.C. cutter exactly the shape of the bottom wing leading edge and the top wing leading edge; then made some Carbon Fiber leading edges using three layers of 10 oz Carbon Fiber. Then I reasoned, “ The race car people are using Carbon- Kevlar-Carbon in combination for explosion protection, why not for leading edges?” After building a few sets, I began wondering, “How do I find out which process is superior?” So my mind started mentally building a testing  device. On July 13, 2014 we had a joint meeting  of EAA Chapter 409 and EAA Chapter 1143. In the week preceding this meeting I gathered  some scrap metal and built this device to batter three sample leading edges to destruction.  Here’s a video of the results.

The set up was a metal basket allowed to free fall from a 90 degree angle with weight added incrementally one pound at a time until the leading edge was destroyed.

Aluminum

1st dent

1 lb

2nd Dent

Each add lb

Final

Destruction

5 lbs

Wood

1st crack

3 lbs

2nd Crack

5 lbs

Final

Destruction

10 lbs

Carbon/Kevlar

1st crack

5 lbs

2nd Crack

8 lbs

Unable to destroy @

25 lbs