You just need to find a way that works for you.
I'm going to use an example I used off-line with Kang.
The rear hook on the SaltyJr plan.
I used exactly the same design for four motor sticks used at Kent last year.
Three of the four failed at the rear hook. The crushing forces are concentrated due to the 90 degree bend.
The web starts to fail, the wire comes loose and moves forward a couple of inches, destroying the stick.
Kang pointed out that some major F1D fliers use this same exact design and it works for them.
It's great that it does.
After my fiasco, I'd never use this design again as it didn't work for me.
After much discussion with Jeff Annis over the design, we came to the conclusion that it was flawed.
We came up with an alternative and I've never had a rear hook failure since. Very slightly trickier to make. Weight penalty is minor but rock-solid in comparison. You bend the wire over the top of the web, then wrap with a few kevlar strands. 0.060-0.070" only is needed. You still use tissue to help secure the wire at the back.
Also the triangular offset. I use silkspan on the offset as this gets a lot of abuse, worth the milligram penalty for the extra strength.
This kind of discussion I always like. I enjoy seeing how others solve engineering problems.
Sometimes they suggest paths forward that no one has thought of before.
And Evan, I'm sure you can dig out the equations for torsional rigidity of a rectangular form.
On a tube, diameter is the largest factor that affects torsional rotation much more than thickness or density.
Regards.
Mike Kirda
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Received on Fri Jul 10 2015 - 14:02:01 CEST