My version: "If it's stupid and it works, it's still stupid."Apologies for the self-quote, but in engineering circles this rule is sometimes expressed more accurately as "if it seems stupid but it works, you just haven't analyzed it deeply enough yet."
The diagonal bracing is for drag/anti-drag load but not torsion. The two spar with two strut is the torsion structure.That leading edge skin is orders of magnitude less stiff than the tube spar, so it will react far less of the load than the skin.
I can't see in that picture what the rest of the wing looks like, but I'm guessing there's some diagonal bracing to take the torsion and drag loads, and as cluttonfred says, the leading edge skin is essentially a fairing.
Hey Marl, welcome to HBA. I haven't talked to you in a long time! Did you get your Starduster back in the air yet? I'm still working on mine (actually, it's more like I'm wishing I could find the time to work on mine). If you stick around here, you'll find this forum is very active and interesting, with a good mix of members (engineers, designers, mechanics, pilots, wannabe's, and crackpots :gig. We do have a group of members that have extensive engineering knowledge and they share it readily.Guys---
If you look into the S-9 that shed a wing you'll find that it was highly modified and had had the bugger flown out of it in airshows. It had a heavier than "approved" engine and was being pushed pretty hard. (Go watch some of those guy's videos---they'll make you hair stand on end with the things that they do!) It looks like he pushed it outside at a fairly high speed for a -9 and built some pretty high -G's before it fails.....
Just saying---the S-9 is a very good design---but this one (regrettably high profile and sensational) accident has been dragged out of storage many times to cast a shadow on the design. If the -9 is built as designed, flown within it's capability, and not abused, it is a wonderful, safe plane.
(And just like a Pitts--the plane can do more acro than prolly 90% of the pilot population can do!!---real bang for the buck if flown smart!!).
Especially strut braced planes. I would expect a clip-wing Taylorcraft to do the same thing, or a Decathlon, if it's pushed too far... Never did I suggest that the S-9 was under designed. For crying out loud, he did a Lomcevak just before that!To address your post about the S-9, I don't see how any reasonable (maybe that's the catch) person could watch that video and jump to the conclusion that the S-9 was underdesigned. It was obvious that the pilot was asking too much of the plane, and that most planes under similar circumstances might suffer a similar fate.