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 body tube. 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 side. |