Composit Bush Plane Suited for Arctic Operations?

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blane.c

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Jun 27, 2015
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capital district NY
Hmmm. Now that is ironic. I came in for a break working outside, at -32, here at BARTER ISLAND , ALASKA and opened up homebuiltairplanes.com to enjoy my coffee with.

AIRGLAS has been making both carbon and fiberglass skis for airplanes and military helicopters, up here for 30+ years. They bond the UHMW to the bottom of their composite skis.

F ATLEE DODGE has been making carbon skis for Supercubs for at least 15 years. I have been torturing a set for a long time on my trapline and out wolf hunting at temps past -50.

CARBON CONCEPTS makes a huge number of non certified carbon parts: skis, belly pods, flaps etc.

Aluminum skis work, but without a 3/8 thick UHMW bottom skin they will stick to the snow. A friend tried to ferry his airplane to another strip to put on new bottoms. I took off in 100 feet. After 1000 feet he shut it down and gave up. If you leave metal skis overnight on the snow they will have a dense coat of course ice crystals on the bottom. The same result, as above, will be made even worse.

For bush operations engineering calculations are helpful as a minimal spec., but durability is what rules the design. Any component that can't take a medium, several minute pounding with a 2 pound deadblow hammer, at -20 is not going to last long. That's what is happening on each crusty, broken ice chunk, take off. The floor protector on the battered Cessna 207 flying in and out of here is 3/4 plywood !

I taxi through brush, as thick than your thumb, all of the time, and my Atlee skis keep on truckin'.
Yes had Airglas skis too, they were great.
 

Jerry Lytle

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Jan 3, 2014
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Newport, Oregon
And I am sure that if you made your composite aircraft in the same manner that your skis are manufactured you aircraft would survive in the far north 1 inch thick at points of high stress and and 1/2 inch at points of low stress it would survive since it couldn't get off the ground.
 

aeromomentum

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Jan 28, 2014
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142
Location
Stuart, FL USA
And I am sure that if you made your composite aircraft in the same manner that your skis are manufactured you aircraft would survive in the far north 1 inch thick at points of high stress and and 1/2 inch at points of low stress it would survive since it couldn't get off the ground.
And by this logic you should be able to make skis using 0.025" aluminum.
 

Jonny o

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Oct 31, 2015
Messages
31
Location
Fairbanks, AK USA
Adding one extra layer to the area subject to impact, is usually all it takes to toughen up the part from the calculated max load/safety factor. On something that is already 5 layers thick, this might add 15% to the total weight of the part.

A Carbon skin will deflect very little before it cracks. A part with no outer skin damage usually will have no internal damage, due to impact (compression loads). Kevlar, like E glass and S glass will deflect a large distance before cracking. ( I am not talking about gel coat ). This can be a bad thing for stiff internal structural parts. If the skin has wide spacing between ribs, it may deflect and return to shape, while not showing internal damage that was caused by compression or impact loads.

Mixing materials, not just composites, with different properties can be dangerous. A part built with an outer skin made out of Kevlar and ribs built from Carbon might be a potential for failure. The Kevlar skin can deflect large distances to shed impact loads and would be very resistant to cracking. The Carbon ribs would be very ridged and not deflect even a small distance without shattering. ( A cracked part still has some strength. A shattered part has zero ). After an impact the Kevlar skin may rebound back to its original shape even though the carbon ribs have shattered. During your walk around the part may look airworthy.

A Carbon skin and Kevlar ribs might be worse. Think of this scenario like an egg. Stiff outer shell with no ridged support under the shell.
 
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