Nothing beats actual test data! But, a little thinking on the front side should save you a few test specimens! (Tesla said of Edison that he could save 90% of his work is he spent 10% of his time thinking about it!

Also, what you are really looking for is the lightest configuration that is strong enough. 'Extra' strength usually only buys you weight. I'll try and finish up the rib calcs and post my spread sheet (this weekend (simple though it is).

With regard to your question about eh loads on the tail, the answer is not much. If you are flying something with a lifting tail (like a 787a0 then you can get some big loads, but I'm thinking this tail is more of just a balance. It may be that a ground-strike condition is what sizes the boom. I mean the wing is sized for 100% of the flight pressure loads. Maybe a gust condition? Still, for this type of aircraft it's not going to need to be that robust.

--- In This email address is being protected from spambots. You need JavaScript enabled to view it., "Philip Lardner" wrote:
>
> I guess there's really only one way to find out - to build a number of test
> ribs in different configurations and see how they perform verses their
> weight. I already have a small stock of 5mm foam board and 248 twill cloth
> (enough for 3 or 4 test ribs) and have just ordered a quantity of Aeropoxy,
> though it will be a couple of weeks before I get my hands on it.
>
> Any thoughts on calculating the loadings along the horozontal stabaliser?
> I'd love to get that done and dusted so I can start putting together a bill
> of materials for ordering. How do you calculate the max load the H-Stab is
> subject to?
>
> Phil.
>
> _____
>
> From: This email address is being protected from spambots. You need JavaScript enabled to view it.
> [This email address is being protected from spambots. You need JavaScript enabled to view it.] On Behalf Of Kenny
> Sent: 09 October 2011 13:32
> To: This email address is being protected from spambots. You need JavaScript enabled to view it.
> Subject: [Carbondragonbuildersandpilots] Re: pressure distribution on a wing
> and rib loads
>
>
> The flexibility of the wood or composite comes from the thinness. Try
> bending 1/16 or 3/32 by .75 wood, and you'll see that it's pretty easy. I
> guess you are talking about the vertical portion in the front and aft of the
> rear. I'm still not keen on them for that. Hmmm, how about just using the
> fiberglass and wrap the front and back the same as the top and bottom so you
> end up with a C-channel around the foam rib. Even in the case of the spar
> pultrusions, they are wrapped (that's the recommendation for the
> manufacturer), so you should wrap them anyway, and now it's heavy and
> over-strength (I think). What you want is just enough, maybe a wee bit
> extra, and that's it.
>
> You want some flexibility in the upper and lower caps or you will get some
> pull-off pre-stress between the rib and the cap, and it will want to
> separate. So, the wood is flexible, and the wet lay-up fabric is flexible so
> they would be much better in this app. If you do use something I think you
> should be looking for an actual layup verses a pultrusion.
>
> I do like your plan for the ribs - I think that should work out OK
>
> I'm thinking right now that that leading-edge stringer can go, IF, the GR/EP
> skins are used for the LE. I'll have to do some modeling to confirm.