Diffusion tip glider
Gary Osoba wrote:
Experimental Pliable Moose Shearwater, circa late '74. 38% higher
AR than anything at the time.
I asked him compared to what exactly. He wrote back:
Wills Wing SST, the Electra-Flyer version, which was essentially
an exact copy of the SST. I was at Torrey Pines the day that Larry Newman
shamelessly took a tape measure to the Wills Wing SST and within a month he was
selling his version. The Bennett Phoenix came along about the same time and
these three had very similar planforms.
The second paragraph in the article linked to above should refer
to the Diffusion Tip glider from Gary not the Shearwater. Gary writes:
This picture is of the Diffusion Tip, manufactured by my company -
Pliable Moose Delta Wings, Inc. The Shearwater was also a model produced by my
company. There were many features of the Diffusion Tip design that were cutting
edge at the time.
Another example was the enlarged leading edge which produced more acceleration
of airflow in the initial region of the airfoils employed. In this case, it was
quite effective and modifications to this area of the airfoils can lead to
appreciable deltas in the maximum airfoil coefficient of lift. This results in
better take off, landing, and thermalling characteristics and allows a designer
additional degrees of freedom in design.
In this case, we held the stall speeds constant relative to gliders with lesser
max CsubLs, and used the extra performance to reduce the total sail area. This
expanded the speed range. With the Diffusion Tip design, we used a relatively
soft foam sleeve around the leading edges to build up the diameter. This sort of
approach was not seen again until UPs Comet some 6 years later, with the stiff
plastic leading edge insert being utilized. This has evolved into what is
utilized in current gliders.