Back in the early to mid 1970s, I built
a Sterling Cirrus sailplane kit. Shortly thereafter I bought my first radio control
system (a used 3-channel OS Digitron
set), and in a somewhat desperate attempt to fly an
RC glider, actually managed to crammed two of its huge servos, a huge
metal-cased receiver, and a NiCad airborne
battery pack (the only part that has not gotten smaller in the intervening 40 years) into the cockpit
Although the cockpit was very spacious, the balsa frame construction was way too
weak to support a radio system, but that didn't stop me... well, not right away
anyway. The ready-to-fly weight was probably three times the recommended 12
Although the Cirrus has a generous
87-5/16" wingspan, with it 25:1 aspect ratio, the root chord is only a little
over 4" and the wingtip chord is around 1". Even with vertical sheer webbing
between the upper and lower main spars, the wing was far too weak for so much
weight. After much work covering the undercambered
airfoil and compound curves around the fuselage with Japanese tissue and
brushing on a few coats of clear dope, it was finally
ready to fly.
The first couple "flights" consisted of tossing the Sterling Cirrus off a little
ridge about 3 feet high, at Klinkin's Field, in Mayo, Maryland. The flimsy wings
flexed up into an extreme curve - it's amazing that they didn't break. The landings
were in soft, long grass, so the craft survived. That was all well and good, but
it was not exactly satisfying flying. Somehow, I talked my father, who was skinny
an no athlete, into running with a tow line in an attempt to get it aloft.
Between the two of us, the Cirrus was rendered unusable after about an hour. Oh
well, live and learn (or don't learn).
May 12, 2021 Update: At long last I managed to get a nice Sterling Cirrus Sailplane kit on
an eBay auction at a reasonable price! All the photos shown here are from my kit.
Posted May 8, 2019