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Max Wensell scratch-built this scale SB-13 from 3-views of the full-size
plane. The wings are a blend of EH 1/10 at the root to EH 3/12 at the
tips, and the tiplets are SD8020, with a bit of toe-in. The wing is
2-piece, made from white foam and sheeted with obechi, covered with
Ultracoat (or similar). Span is 100 inches. The fuse was molded using
fiberglass and polyester resin. Ailerons are driven by Cirrus CS-20
servos (marginal!!) and will probably be upgraded to something a little
stronger; Max has already noticed a little flutter when pulling out of a
short dive. They were chosen due to the thinness of the wing. There is a
tow attachment built into the front of the fuse, and the tiplets have an
option for spoileron controls.
The picture was taken a couple of hours after the maiden flight at an
airstrip in northeast Oregon at the Wallowa Lake Fly-in (the lake is at
the foot of the mountains behind Max). Max tossed the plane in high
grass a few times to get the CG and reflex right, then strapped it,
piggy-back, onto a tug plane and got lifted up to about 200 feet, where
the plane was released. It flew very well. It was responsive, reasonably
friendly, and had no obvious tendency towards a death-spiral. A couple
of flights later, in the middle of being boosted back up to 300 feet by
the tow plane, then cradle support disintegrated, spraying down pieces
of red-painted wood which we thought were pieces of Max's tiplets! But
they turned out to be pieces of cradle, and the only damage to the wing
was a slightly crushed LE near the root. The plane flew fine, the LE
damage was not evident until inspection after the landing. Max fixed the
LE, and later had the SB-13 towed up in the traditional way, behind a
tug.
David Stone
The wing
is one of two entries from Embry-Riddle Aeronautical University in the
unlimited class of SAE Aerodesign '98 East. The wing has a 16 foot
wingspan and is powered by three K&B .61s turning custom designed and
CNC machined props. The center section is 2024 aluminum and the outer
panels are vacuum bagged graphite epoxy and fiberglass over blue foam
cores. The plane's empty weight is about 40 pounds. It won the award
for best design. A 1/3 scale test model was built to verify stability
and control of the design. Valuable lessons were learned in the design
and construction and test flying. An improved version will compete in
SAE Aerodesign '99.
Pictures by Chris Kelle
Here are a few shots of the RAVEN from Bsquared (Courtesy of Vaughn Entwistle)
