Existing single cantilever tubular spar wing designs?

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dog

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Dec 29, 2019
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talking about tapered thickness spars - the Gossamer Condor or its offspring used an aluminum spar that was etched towards the tip. Cannot remember the etchant: caustic soda ??
When building the gosemer condor they needed
tubular carbon spars,that they built on aluminum
tubing and then dissolved the aluminum, as it was the only way to free the carbon.
Didnt know about chemical tapering, could be done simply by dipping, like a candle in reverse.
 

David L. Downey

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Aug 7, 2019
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I have read of some of the other above and beyond treatments from the bad old days, but not this one. I'd love to read about it if you have an idea of where to look for it...
I wish I had the actual report as well. But I got it first hand from the principal research Engineer doing the work. Since I cannot produce the proof I probably should have said something like "The US Air Force Labs purportedly..."
 

SMORGAN

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Dec 9, 2016
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Sydney Australia
I have a book called Gossamer Odyssey by Morton Grosser, the Condors tube structure was etched internally with swimming pool chlorine I think. By filling the tubes when vertical and the chemicals poured in at the top then the lower part of the tube was etched more than the top due to the length of time in contact with the chemical. Probably needed a bit of experimentation. For the Albatross the carbon was wrapped at various angles to give the strength needed and the aluminium was etched out completely.
See the attached images.


DSCN9168.JPGDSCN9169.JPG
 

TFF

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Apr 28, 2010
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Memphis, TN
Back in the day, Model Aviation had an article on the electric Solar one as it was powered by an RC motor. There was one picture of wrapping the spar.
 

rv7charlie

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Nov 17, 2014
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671
Location
Jackson
Thanks for the references to the various iterations of the human powered stuff; was too easy for me to forget there were multiple versions. The distinctive one for me was the pure carbon version, with the aluminum completely etched away.
 
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