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TJS-1 - The first RC plane designed and mostly built (with Dad's help) by my 14-year-old son.
Features:
Original design, no plans exist
Hot-wire cut from EPS foam
Single aileron
Acrylic craft paint used
Specifications:
Wing Span: 33.5 in (85 cm)
Wing Area: 402 in2 (25.9 dm2)
Airfoil: 11% Clark-Y
Wing Loading: 6.5 oz/ft2
Controls: Throttle, Elevator, Aileron
Servos: Hextronik HXT900 (two)
Receiver: Corona RD820
ESC: TowerPro Mag8 25 amp
Battery: Flightmax 3S1800 20C Lipo
Motor: Towerpro 2409-18A Brushless
Propeller: TowerPro 8x3.8 (pushing)
All-Up Weight: 18.0 oz (510 g)
The TJS-1 first flew on December 13, 2009, in Tehachapi, California. The weather was cold, windy, cloudy, and rainy. This was an untested design, so we weren't sure how the plane would fly. The first flight was made at full throttle with a hand launch into the wind, which sent the TJS-1 right into the ground breaking the nose. After repair, the second flight was made by skidding along the grass. The TJS-1 barely took to the air, but we were encouraged. After this, we added some downthrust to the motor and allowed for more up elevator movement. The third launch was again a hand-launch with the same result (broken nose). After adding even more motor thrust offset, the fourth flight was a takeoff along the grass and after a long full power run, the TJS-1 leaped into the air.
The long takeoff run is believed to have been caused by very little clearance between the ground and the wing. The plane flew well, and only required a slight aileron trim, although the wind prevented any really effective trimming. For level flight, the TJS-1 requires a great amount of both motor thrust offset (see photo below) and up elevator. The TJS-1 was flown by it's designer for a few minutes despite the wind. After this successful flight we were cold and called it a day (but a very good one!)
The TJS-1 required a lot of motor thrust offset because the tail is short, which causes a shorter moment, therefore less stabilizing in pitch. If the tail were longer, not as much offset would be required (see my RPG plane.
