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Re: aktinofibril intercalation, JCunningham



Me, I think. It's not a new hypothesis. I've spoken of it in talks several times, starting in about 1999. Haven't written anything on it yet. Due to the intercalated nature of the actinofibrils, it would be virtually impossible to keep them rigid with respect to one another. I've not attempted to determine likely maximum extension because I don't consider the maximum to be terribly important to flight control, but would expect it to be on the very loose order of 10 to 20%. The far more important extensions and contractions would have been on the order of fractions of an inch (flutter inhibition and also roll control due to the impact on camber). A localized 2% change in length due to differential movement between adjacent fibrils would have an enormous impact on aeroelastic number and the bistable and flutter limits. Different areas of the wing can operate somewhat autonomously, but not at all like airliners, nor would that be the intent. The important effects need to take place over localized areas about the size of your hand, but it doesn't hurt if the effects extend further. It has relevance to both the inner and outer wing. The fibrils are not shorter in the inner wing (about 10 cm), but they are more amorphously aligned and not as densely spaced. Note that there is no consensus on this yet.

As an aside, for the broadwing concept, I see no way for the chord of the inner wing to be extensible enough to allow for free motion of the hindlimbs when launching. If it is slack enough to allow the rear legs freedom to launch, then it will be slack enough in flight to present severe problems for both flight efficiency and flight control. Keeping it taught would require limitations on hindlimb mobility in flight that don't seem practicable to me. When the inner wings go slack, the animal will be on the ground in short order, whether intended or not.

----- Original Message ----- From: "david peters" <davidrpeters@earthlink.net>
To: "jrc" <jrccea@bellsouth.net>; <qilongia@yahoo.com>
Cc: <dinosaur@usc.edu>
Sent: Monday, July 16, 2007 7:35 AM
Subject: Re: aktinofibril intercalation, JCunningham



Jim,

I am familiar with the intercalation. But I don't recall hearing the hypothesis, until now, that the fibers moved longitudinally. Who is that author of that hypothesis and where is the paper?