Full Size Printed Plan 1/2A Witch Hawk By Jim Clem a potent contest machine.
Regular priceSale price
Unit price/ per
& Building Notes
No materials. Plan only
Full Size PlansPrinted on a 34” x 24” Sheet
Four page article with building notes and photos
Competition Free Flight
WINGSPAN: 42 inches
WING AREA: 237 square inches
LENGTH: 32 inches
WEIGHT: 5.5 to 7 ounces
By Jim Clem
The small 1/2A Witch Hawk. (237 square inches of wing area) was designed for the specific purpose of achieving a glide comparable to the larger 1/2A contest ships. This quality, combined with a hot climb, has produced a potent contest machine.
A long tail moment arm was used to place the 27% stabilizer approximately 20 inches from the CG. Had the rudder been placed aft of the stab, the fuselage would have been too long, resulting in the need for a longer nose moment to achieve a proper balance. Consequently, the rudder was placed forward of the stab. This, of course, is nothing new; it's seen all the time, but not too often on AMA gas models. The rudder placement has proven to be a nice arrangement. It is far enough from the prop blast not to be troublesome and it eliminates the need for a lot of left engine thrust. The two degrees used on the prototype was excessive . . . both Witch Hawks I'm now flying have only about one degree of left thrust. Bill Jenkins' "hawk" has about the same, or less. During the development stage of testing several models, the rudder was increased slightly in height. The original rudder was found to be "marginal" since it permitted the airplane to occasionally roll under high power.
The Witch Hawk design has met the original objectives. It can hold its own in the glide department with the larger 1/2A ships; and its fast climb, of course, was never in doubt. The ship also does well without a lot of the wash-ins and washouts usually associated with low thrust designs.
The Witch Hawk has gone through a long period of testing and development. A special thanks to Bill Jenkins of Memphis and Jim O'Reilly of Wichita for their help in this development. Jim supplied valuable technical data, while Bill did extensive flight testing with his Witch Hawk. Keith Williams of Bartlesville, Oklahoma, built the first ship and his input was of great value. With help like this, it makes developing a new design much easier.