This model is based on the Estes K-57 SkyDart kit from
the early to mid 1970's. The 2X version uses 2" NCR tubing
(from old NCR shuttle kit), and a custom nose cone turned by
Balsa Machining Service. The wing is 1/2" (.55" thick) blue
foam sheet, with no reinforcement other than 1" wide 1.5 oz
glass cloth to give ding-resistance to the leading edge.
Rudder is 3/16" blasa, removeable for transport.
Span 26", area 270 sq in. Liftoff weight approx 11
ounces. Power by E12J reload in a 24mm "RC" casing.
Radio controlled by mixed elevons. Futaba 8UAF
Transmitter provides electronic mixing so each servo
directly drives one elevon. Hitec 555 receiver and HS-60
servos. 50 mAh nicad battery pack. W.S. Deans whip antenna
inside of body tube.
Model was not covered or painted as seen in these pics,
to see if it worked out OK in test flights first. Most
flights launched at 45 degrees, some at 60 degrees, using a
C-rail. Altitude about 400 feet, glide time about 60
Servos installed directly into wing by cutting
outline in foam slightly undersized. 1/16" balsa
scrap glued flush with top of wing, the 1/16"
thickness makes up for the difference in thickness
of the blue foam and the servo. Opening covered
over by package tape. Servo output arm sticks
straight down, to drive the elevon directly via a
short pushrod. Troughs cut into foam to run the
The pic at left shows the bottom of the wing
before the wing was glued to the body tube. Servo
wiring runs inside small openings in body tube.