Kestrel (oz7923)

About this Plan

Kestrel. A 46-inch span powered sailplane for .020 engines and single channel radio control.

Quote: "An 020-assisted soaring model for rudder-only, offers relaxing, long flights. Kestrel, by David Boddington.

TWITCHING the transmitter levers of a high-speed guided missile demonstrates present-day radio equipment is accurate enough to follow every shake of the hands. It is exhilarating, but it needs an antidote. Kestrel is such an antidote. Flying is slow and easy with only rudder control. This type of model can give hours of fun, and it can be flown from any small flying area.

The Kestrel is the fourth in a line of powered gliders. The design started life as a pure glider for thermal and slope soaring. Unfortunately, the nearest slope soaring site is about 50 miles away and with the vagaries of English weather, often results in an abortive day's would-be flying.

Having given up free-flight flying eight years ago, my attempts to tow the model up on the line proved that my fitness had deteriorated and my legs would do a maximum of 6 mph. But the model required a towing speed of about 8 mph ground speed in still air conditions. By substituting a great length of 1/4 in flat rubber, it was possible to achieve the same results without expending so much energy, or needing a hill. But long grass sliced through rubber like a sharp razor blade. So back to the building board. With a large hill, uncooperative legs, 30 yards of rubber cut to assorted lengths and with a Cox 049 mounted on a pylon and, presto, I was in business.

This original 53 in span model was eventually joined by a 36 in, 010-powered design featuring similar construction to the Kestrel shown here. 'Picconiny' proved delightful to fly. It gave an interesting comparison between the sheeted, undercambered wing used, and the conventional built-up, covered wing of the previous design. The sheet wing had a higher lift to weight ratio, allowing a slower flying speed - excellent for calm days and thermaling. For heavier and more bulky radio gear the Apprentice (oz1621) was drawn up to cope with 020 to 049 engines, and used a constant-chord conven-tional wing of 49 in span. Although it could be flown in more varied weather conditions, and was tough enough as a slope soarer, it did not possess the power-off characteris-
tics of the Picconiny. The Kestrel resulted.

I am convinced of the desirability of positioning the engine on a pylon over the wing. The high thrust-line helps avoid nosing-up following turns and dives. The high engine position is more efficient than the conventional nose set-up. It is surprising that this layout has not been employed on more models, particularly beginner's designs, since advantages include the non-sensitive engine side and down-thrust conditions.

The Kestrel (virtually an enlarged Picconiny) was constructed quickly because I could not wait to try out the latest ACE Pulse Commander outfit..."

Hi Mary/Steve - Here is David Boddington's Kestrel from American Aircraft Modeler magazine issue 02-70.

Direct submission to Outerzone.

Supplementary file notes

Article pages, text and pics.

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