Re: alula

["James R. Cunningham" <jrccea@bellsouth.net>]

Phillip Bigelow wrote:

> The main purpose of the alula is to prevent "stalling" at low
> glide speeds (for instance, when landing).  Modern airplanes
> have a similar device for use during landings.
>                   <pb>

I own four airplanes, a J-3, a PA-11, a PA-12, and a PA-28-150.  Insofar
as I know, none of them has a device of this nature installed. However,
John McMasters, an engineer at Boeing (and author of a couple of
pterosaur papers), did install one (called a snag) on a wind tunnel
model, and found it to be essentially non-functional. Consequently,
Boeing never pursued the concept.  A number of modern planes do use VG's
(vortex generators), and I have flown with them in an air race, but they
don't have the same configuration as an alula, and don't appear to serve
the same purpose.  We used them in selected locations to increase cruise
speed (they can be used to decrease stall speed too).  On the other
hand, since birds, bats, and pterosaurs all have an alula-like
construct, it suggests alulas do serve a function in biological flight,
perhaps associated with cranked wings since they are located near a
crank..

JimC