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 (as produced for the 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" balsa, removeable for transport.
Span 26", area 270 sq in. Liftoff weight approx
11 ounces. Power by E12J reload in a 24mm "RC"
casing. Also sometines flown on an E6, a bit
marginally due to the weight.
Radio controlled by mixed elevons for roll and
pitch. 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
The model was not covered or painted as seen in
the test flight pics, to see if it worked out OK
first. Most flights launched at 45 degrees, some at
60 degrees, using a C-rail. Altitude about 400
feet, glide time about 60 seconds.
The servos were installed directly into the wing
by cutting the servo outline in foam slightly
undersized. 1/16" balsa scrap glued flush with the
top of the 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
(later covered over by Towerkote). Servo output arm
sticks straight down, to drive the elevon directly
via a short pushrod. Troughs cut into foam to run
the servo wiring towards a small opening cut into
the body tube along the glue joint (epoxy was not
applied to the area near that opening).
The picture at right shows the bottom of the
wing before the wing was glued to the body tube.
Servo wiring runs inside a small opening in the
body tube. The gray square object to the left in
the pic is a piece of 1/4" Plastruct Square tubing,
epoxied into the wing at 45 degrees, as a socket
for the plug-in removeable rudder on the top