2mm Depron foam sheet for fuselage; wing; horizontal and vertical stabilizers; wheels
1.2mm x .8mm x 1 meter carbon strip for wing LE
1mm x 1 meter carbon rod for elevator pushrod
1.4mm x 1 meter carbon rod for landing gear legs
.020-inch diameter music wire for aileron pushrod; elevator pushrod ends
Thin and medium foam-safe CA glue
1/64-inch plywood for vertical fuselage doublers
ParkZone PKZ3352 three-channel receiver/ESC DSM2/DSMX
7mm geared brushed motor
1s LiPo battery (150 to 160 mAh)
Sharpie permanent markers for coloring model
Goodyear/Formula One air racers have been a favorite of mine since I first began flying Control Line Scale Racing with my dad in the 1970s. Indoor RC Pylon racing is a natural progression. This rendition of the full-scale Falcon Special is a 1/17-scale Depron foam electric motor-powered RC model airplane.
The models’ size and layout were inspired by Bob Selman’s Boo Ray Cassutt design (bsdmicrorc.com). The flat wing, wing spar on the LE (leading edge), elimination of rudder control, and single aileron are my applications. The single aileron control is adequate for turning the model left or right when combined with up-elevator. It was unnecessary to enlarge the tail feathers as is often the case with scale models.
Properly trimmed, these little flyers are stable and fast! The models can be flown outdoors, but at 3/4-ounce all-up weight, the wind should be dead calm.
Construction is easy, but the components must be built straight because the wing and horizontal stabilizer alignment are dependent on a perfectly perpendicular fuselage cruciform. Short-coupled designs are easier to fly than the longer fuselage length models and the Falcon Special is one of the best-handling racers.
The recommended motor is the GWJ 7 mm black brushed motor/gearbox combo from Bob Selman Designs. It comes with a propeller saver installed, but the included micro plug needs to be attached. The company will solder on the plug for a modest fee. A GWS 4040 direct-drive propeller perfectly fits the propeller saver.
You can build two or three racers from a single sheet of 10 x 30-inch foam and 1-meter lengths of carbon fiber (rcfoam.com). Adhesive is thin and medium foam-safe CA. Hot glue is used to attach motor and as pushrod-end retainers. I don’t like to use CA accelerator during building, but I do keep a bottle handy for field repairs.
Building tips: wipe down any component where glue or hinge tape will be used with 91% isopropyl alcohol to greatly improve adhesion. Depron will snag and tear while cutting unless a razor-sharp knife is used. Using snap knives is an easy, inexpensive way of keeping a sharp cutting edge. I get mine from HobbyKing (hobbyking.com), but they are readily available elsewhere.
When it’s time for your first flight, if possible have a friend hand-launch the model with a slight forward motion at half throttle. It simply needs to be launched level. If it gets away from you, kill the throttle to minimize damage to the model.
I use roughly 25% exponential on both elevator and aileron. Once airborne, the model will fly nicely at 1/3 throttle. I don’t recommend full throttle until model is trimmed and you’re familiar with its flight characteristics. A full-size gymnasium is an ideal flight venue. This is not a living room flyer!
After rough landings, make sure your brick and motor are still securely attached. I found that the motor will often slide forward in the gearbox after a collision. Gently push the motor back in place, aligning the spur and pinion gears.
Full throttle racing with two or three others is a fun and exciting RC flying experience.
Read the full build article with build photos in the Fall 2015 issue of Park Pilot. Not a subscriber? Subscribe now at www.theparkpilot.org/subscribe