The
next logical progression was a P-30.
The restrictions of this class forced a redesign
to accomodate a proportionally shorter fuse
length, as well as a shorter motor. The resulting
Ellipsis P30 was not quite
as successful as I’d hoped, but still
good enough to place in a few competitions
before the model was lost. This ship was blown
off an airfield plateau into a heavily wooded
and impassable escarpment, never to be seen
again.
Ellipsis P30
I
then took the flying surfaces and propellor
unit of the Mini-Toots and
attached them to a long, slim diamond fuselage
to evaluate its stability prospects. This
Ellipsis-X flew considerably
better than the Mini-Toots.
It was also trimmed out with an alternate
flat-bottomed wing of very light structure,
resulting in a higher climb but little performance
improvement overall.
Ellipsis-X
Ellipsis-X prompted me
to build another 150 sq. in version of similar
layout – named Ellipsis-150,
naturally enough. The structual development
was still progressing in my mind, and I
reduced some more weight. Specifically,
the wing LE and TE were both constructed
of only of 3/32” square balsa, which
proved to be amply strong. This model has
shown prospects of being an exceptional
performer even though it hasn’t yet
been trimmed past about 75% power of its
35g motor. Still good enough for local contest
successes but as yet I’ve had no opportunity
to spend time on trimming it further.
Ellipsis-150
Some decry low aspect ratio wings of semi-elliptical
planform as being poor performers and prone
to tip stalls. But I've never encountered
the latter "problem," and all the
airplanes presented here have been stable
performers with excellent, slow glides. Such
wings have the advantage of being extremely
light while still retaining adequate bending
strength. They are also remarkably warp resistant.
Ellipsis-150 wing
The Ellipsis and Ellipsis-150
are now rarely flown in earnest since there
aren't many contests to take part in. As
a result I haven't bothered to develop the
design any further - though I know full
well that I could now build a much lighter
version of the larger airplane, and expand
its performance envelope substantially.
The thought of a 300 sq. in Mulvihill
has tempted me on several occasions, as
has the idea of a flat-bottomed '150
wing, but the present airplanes
do well enough to make the project irrelevant
at this time.
