Bob Massmann writes:
I have the Flipper which is very similar.
My first HLG was also a Bridi Flipper, very similar to the Tercel. If I
remember correctly there were some differences in the shape of the tail,
but otherwise they were almost alike.
Low speed handling was great, but range and L/D was a bit lacking. The
other problem was the bulkhead at the leading edge of the wing, the one
that the wing's leading edge dowel plugged into. That whole area of the
fuselage structure was very poorly designed, and essentially had all the
wing loads transferred across the grain of the balsa instead of parallel to
the fibers. Anything less than a perfect landing would break some part of
that structure. I'd recommend at least adding some fiberglass tape and
epoxy around that area.
The other culprit from a performance standpoint was the short wingspan.
Stretching it out to a full 59 would significantly help performance. The
Zephyr was a very similar model from that same era, and also had a short
wingspan. Most of the Zephyr flyers I knew had added some additional rib
bays to the wing to stretch it out to the full 59.
Besides the shortage of range and penetration, the other quirk involved the
Eppler 205 airfoil. It has a mush mode of separated flow and high drag
that develops well above the final stall break. If you don't pay close
enough attention and let it get too slow, it will sneak into a mush that
will require a lot of altitude to fully recover from. A skillful pilot can
use this almost like spoilers for glide path control on landing, but most
of the time it's a nuisance and a trap for the unwary.
Joe Hahn scratch built a 2-meter scaled-up version of the Flipper that flew
quite well.
My second HLG was a Vertigo. Foam wings with balsa skins, heavier, more
legs, but couldn't thermal nearly as well in the small, weak lift we get
around here.
About that time I was also reading the part in The Old Buzzard's Soaring
Book about how you could make an airplane heavy and fast and search
better, or keep it very light and thermal well but not search as far. It
was presented in the book from an either/or point of view. It was quite
clear to me that the Flipper and the Vertigo represented classic examples
of the two schools of thought, and that in the widely spaced, small
diameter, very weak lift typical of this area, neither approach was getting
the job done. Joe, who worked downstairs from me in another department of
the same company, was coming to similar conclusions with his own HLG
experiments. We questioned why it had to be either/or; couldn't we come up
with a model that could do both? We also noticed that the state of the art
in HLG's at that time (1992) seemed to be based on scaling down larger
models, airfoils, planforms, structures and all, to HLG size, rather than
looking at the unique demands of HLG's on their own merits. We started
comparing notes and collaborating on designs, and six fuselages, seven
tails, eight wings and about 150 hours of computer work later we had the
first Monarch. Shortly after that, Bob Massmann, one of our friends in the
DARTS club, hung up his Flipper for one of our first kits.
I still have my Flipper, and about an afternoon's work could make it
airworthy again. It was a sweet handling airplane for its time, but I don't
really have any desire to go back.
Don Stackhouse @ DJ Aerotech
[EMAIL PROTECTED]
http://www.djaerotech.com
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