RE: [RCSE] RE: Inverted Dihedral

[Scobie Puchtler or Sarah Felstiner]

There has got to be more to it than just ground or surface effect. Swallows
use significant anhedral for ANY non flapping glide, ESPECIALLY when
circling in thermal lift or making a pass in front of a lifty slope. For
them it is clearly 'best glide', and they always use it to some degree when
not powered (flapping). In extended glides or when its really obvious that
they're trying to climb in lift, the pose gets even more exaggerated. There
is fairly significant sweep to the wings in this mode.

Thoughts anyone?

Lift,
Scobie in Seattle

 -Original Message-
 From: Brett Jaffee [mailto:[EMAIL PROTECTED]]
 Sent: Wednesday, March 22, 2000 11:09 AM
 To: Rodger Hamer
 Cc: [EMAIL PROTECTED]
 Subject: Re: [RCSE] RE: Inverted Dihedral


 Possibly to enhance the ground effect as they come in low?  I've
 seen video of a 2 person ground effect vehicle that had a similar
 wing tip down look.

 Rodger Hamer wrote:

  I was wondering about the fact that when ducks are on final, they always
  seem to have their wingtips curved downwards...possibly as an
 airbrake and
  to avoid tip vortices and wingtip stall? Gulls also seem to assume that
  flying configuration.
  Rodger
  - Original Message -
  From: "Ciurpita, Greg" [EMAIL PROTECTED]
  To: "'RCSE'" [EMAIL PROTECTED]
  Sent: Wednesday, March 22, 2000 7:25 AM
  Subject: [RCSE] RE: Forward sweep (stability)
 
   Ignoring the practicalities ...
  
   From Simons' "Sweep forward actually aids control
   at low speeds, delaying wing tip stall
 
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Re: [RCSE] RE: Inverted Dihedral

[Moved by the wind.]

Scobie Puchtler or Sarah Felstiner wrote:

 There has got to be more to it than just ground or surface effect. Swallows
 use significant anhedral for ANY non flapping glide... There
 is fairly significant sweep to the wings in this mode.

It maybe to neutralize the dihedral effect of the wing sweep.  3* of wing sweep is 
about equal to 1* of dihedral.  If the wing is
swept 40* that's an effective dihedral of 13*.  If they have 13* of anhedral the two 
would cancel each other out.

Rich Border

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