Re: Re: Solid Wood F1D Motorstick [1 Attachment]

From: Jake Palmer <82.jake_at_gmail.com>
Date: Fri, 10 Jul 2015 14:27:34 -0700

That design is similar to one shown in Ron Williams book. The difference
is he used a top hat bend on the wire that wrapped back over the top of the
web. The top hat bend leaves a little loop you can use to attach the
bracing wire.

On Fri, Jul 10, 2015 at 2:02 PM, mkirda_at_sbcglobal.net [Indoor_Construction]
<Indoor_Construction_at_yahoogroups.com> wrote:

>
> [Attachment(s) <#14e79c677a45da21_TopText> from mkirda_at_sbcglobal.net
> [Indoor_Construction] included below]
>
> 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
>
>
Received on Fri Jul 10 2015 - 14:27:43 CEST