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All techie stuff here
#384108
Bouyo wrote:I see it. There's a graph of it in the lecture posted above. Am I missing something?
Nope- but somebody else is... with determination... inexplicably.

Ryan wrote:In my paraglider, I like to weight shift a lot, but in active air there's no getting around the need to work the toggles actively. It does not feel like I am flying with my body, it feels like I am working a wing, and that wing is flying and carrying me.
Poor bastards. Well, not when they're loading up their car/burrow/rollerblades/whatever- but in flight, you can't help but sympathize with those wearing what amounts to an air condom.
Red wrote:These simple tricks are simply not available on today's HGs, and they should be.
Ain't that the truth! I still want flaps for my Discus- would have them, too, if I could have managed to get my wing into Tomas Pellicci's shop to have them fitted.
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By AIRTHUG
#385302
Okay... it took me a while to get to it... but I watched that Albion Bowers presentation. Really good, really informative... THANK YOU for sharing that golden nugget!

In other thread there was some discussion on some interesting (progressive?) glider designs (Northwing is stepping outside the "established" box)... and that lead to some talk of other design ideas... which reminded me to come back and check this thread and video...

In terms of their lift distribution, compared to hang gliders (or what I know of hang glider's, anyway... since there's no wind tunnel analysis data)... we may still be using the elliptical curve rather than the bell shaped curve? Hard to say, with the 3-dimensionality AND flexibility of our wings. I know most gliders employ an S shape along the trailing edge, and twist is not applied uniformly from root to tip... but even just seeing the twist profile of a wing, IN FLIGHT, is tough.

In terms of having downwash at the root, and UPWASH at the tip... yea, we definitely got that, hence the nose up pitching force that gives us stability.

Looking at their numbers- while it does look like they've successfully created, measured, documented PROverse yaw... they're not getting much. And at the end in the Q&A, the guy asking about designing for aircraft that operate at a wide variety of speeds... that's us! And the answer was, it works at the speed for which it is designed (and just a little bit, from the data). Not to knock this breakthrough... but that kind of squelches the applicability for us hang glider pilots. We maneuver at such a wide variety of speeds and angles of attack... and honestly, adverse yaw doesn't create much problem for us at most of those speeds. The improved efficiency would sure be nice, though! But anyone that's experienced PIO knows right around where our biggest adverse-yaw speed is... and for me, this research solidifies why going slower *OR* faster seems to lessen the adverse yaw. Because the aircraft design minimizes it at certain speeds... which basically means it will have lots of it at other speeds, because the optimizations aren't effective then.

Very interesting stuff! I love learning!!!
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By Bouyo
#385322
AIRTHUG wrote:or what I know of hang glider's, anyway... since there's no wind tunnel analysis data
Ah, don't believe that for a second! Here's a quick google search result (old paper but totally relevant) http://www.johndickenson.net/pdf-files/ ... glider.pdf

It's technical, but the conclusions section is illustrative and the myriad graphs are illuminating when you wrap your head around them.

As for 'not much proverse yaw' and only at certain speeds: I'd say that it's better to think of it as 'no adverse yaw'. If that's achievable at a speed your going to be doing the majority of your maneuvering at for a given aircraft then it's still a big deal I think. It's probably only really relevant to commercial passenger planes really, but who knows what rigid designs will evolve into in the future?
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By AIRTHUG
#385339
^ that data is from 1981. Hang gliders today are just a little different in planform, twist amount and distribution, airfoil, frame and sail rigidity, sq ft/lb wingloading...
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By Everard
#386024
This is not really my field, but I just came across this flying wing scaled down radio-control glider that NASA is developing:

Image Flying Wing-Shaped Experimental Airplane Validating New Wing Design Method
Future aircraft fuel efficiency could be dramatically increased thanks to ideas validated with increasingly complex subscale, experimental, remotely piloted aircraft at NASA's Armstrong Flight Research Center in California.
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