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Since there was ony one pylon racer readily available locally and I like
to be different, I decided to design my own. Having seen the other designs
in action, my observation was that they are all pretty much unstable.
This year I witnessed more than one race being won, not by the fastest plane,
but by the one being flown in the most accurate and predictable manner. It seemed
that the biggest challenge was to fly in a straight line between the pylons.
So, with stability the first design criterion, I did a bit of thinking
about what
makes an aeroplane stable and decided that it should have a long tail moment,
short nose and a high aspect ratio wing with a sweep-back leading edge.
The proven MH43 airfoil was an easy choice.
The result is a delight to fly with as much stability as anyone could ever want,
but what surprised me most was the speed. The Arrow is FAST and
impresses everybody when they see it flying for the first time.
Now the pilot needs to brush up on his flying skills so that it more
closely match the
| SPECIFICATIONS | Wing span: 900mm (120mm root, 70mm tips) Profile: MH43 (that was the intention) Mass: 530g Motor: Graupner Speed 400 6V (+ flux ring) Propeller: Graupner Cam Speed 5x5 with Graupner Precision Spinner Cells: 7 x Sanyo 500AR Current drain: 9A static Speed control: Robbe 18A, BEC Servos: Aileron - Hitec HS-80 Elevator - GWS Naro HP (9 grams) Incidences and trust lines: All 0 deg. Design: Christo van der Merwe |
| CONSTRUCTION | Wing: 1 Layer
glass on solid Balsa Fuselage: Glass (lost foam method) Tail: Balsa V-tail, Solarfilm covered |
| PERFORMANCE | Speed looks promising with excellent
penetration - no doubt due to the sleek design, high aspect ratio and thin wing profile.
Launches are rock-solid and handling is very stable with a full throttle flight time of
over 3 minutes with 500mAh cells. On third launch an unintended touch-and-go on tarred runway (full down trim on transmitter) removed approx. 40% of the prop, but she climbed away steadily and flew well, albeit a little slower. Out of curiosity a Speed 480 Race motor was fitted and although is was a fair bit faster (at 19Amps!) and a lot of fun for 2 minutes, I didn't feel the same kind of satisfaction after the flight. Perhaps experimenting with different props will change that, but it seems that this design suits the 400 class motor particularly well. |
