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WTB: J3, C85, Electrical

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There are a few Cubs, Pitts, Bellancas of different versions running around the Vegas valley with wooden spars and wings with little to no abnormal issues.

That’s not to say it could or wouldn’t cause an issue, I’ll let you all know once I get the Cub I just purchased out of Colorado here in Vegas.
 

bob turner

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If you take care of them they are fine. Every time I have pulled a wood wing apart there has been a splice somewhere, and usually another splice was needed. Not true of metal spar - inspect and recover.

My Decathlon has wood spars. They are perfect. Every single flinging year they require a four hour inspection per an AD. Good thing I can do it, or I would be in the poorhouse.
 

huston marlowe

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I have had both. Made sort of a study of them. My OPINION is that Piper did a clumsy job of the Aluminum spar design. No question the Aluminum spar design is much stiffer and stronger and heavier than the wood spar design. Aesthetically the 12 rib design is superior , without all the bumps showing through the fabric from spar taper and N panel. I like the simple leading edge too. If I were to build a wing it would be the wood spar design with spars cut from Aluminum extrusion. More opinion, the two designs should not be interchangeable . They are too different.
 

bob turner

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And yet Piper interchanged them. A number of Cubs have flown with one of each, and so far no reason not to do that has surfaced. The wood wing is lighter, and when uncovered it is more attractive if done right.
 

AKJurnee

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I also think our extremely low humidity might not be kind to wood over time.
I’ve never heard of any issues with low humidity, the spars if done right have several coats of spar varnish which seals out moisture anyways. I’ve seen more 1800’s wood structures out in desert still standing than out east in high humidity.
 

1940_owner

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Have flown with neither wood spars nor wood props. However, had a new Sensinich wood prop for my A65 before a change of plan (profile photo clue). Never installed it, but the instructions were very clear about checking prop bolts with seasonal humidity changes.
 

AKJurnee

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Have flown with neither wood spars nor wood props. However, had a new Sensinich wood prop for my A65 before a change of plan (profile photo clue). Never installed it, but the instructions were very clear about checking prop bolts with seasonal humidity changes.
Apples and oranges. The wood prop swells or shrinks with/out humidity, there’s little holes in the leading edge that doesn’t seal the prop, same with hub area. Flying in the humid air helps drive moisture in the wood, especially precipitation. The Prop hub friction between the plates and prop is what turns the prop, not the hub bolts. So when the prop shrinks, the friction lessens and could slip and crack or make smoke.

Wood spar wings are essentially sealed with spar varnish then wrapped in fabric wing covering. Flew a wood spar aircraft in the most corrosive environments in the US for years, inside the wings at recovering looked new, except for a few metal fasteners.
 
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The Prop hub friction between the plates and prop is what turns the prop, not the hub bolts.
For flanged crankshafts, the bolts hold the hub tight to the flange compressing the wood so face friction transfers torque from the flange to the wooden propeller with the drive bushings as back-up. For low horsepower tapered crankshafts, torque to a wood propeller is also transmitted through face friction according to Sensenich with bolts as the back-up. A slightly loose wooden propeller hub even it it feels tight will heat up from vibration, breaking the glue bonds and coking the wood. Proper bolt torque prevents movement between the flange and the propeller hub.
 
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