Our original airplane, the Axon, has finally died after several outings since the last update – its final flight ended in a giant hedge of blackberries (downwind stall and spin in a gust), and Guthrie bravely, with a little bloodshed, extracted the wreckage for salvage – he had to yank the plane out by its tail, and it got pretty well shredded. Now we now know how much wind is too much – 14 gusting to 20 mph is too much wind, at least for my piloting skills.
Meanwhile, I’ve been chipping away at a plane of my own design. I’m calling this new plane the Bee (original, I know). It has a shorter, wider, thicker wing with quite a bit more area (7 x 48 inch Armin wing for you geeks). I also built the wing with about 5 degrees of dihedral, for better stability. The idea is that this would be a slower, gentler plane, that we could possibly fly at a vacant lot within walking distance of the house. The Bee was built with the same basic methods and materials as the Axon, (Dollar Tree foam board, hot glue, packing tape, duct tape) -
- I can’t give enough credit to youtube cult hero Ed for developing this method. I did use carbon fiber rod for the wing spar and landing gear. I used about $4 worth in the plane, and it should be reusable, barring a truly catastrophic crash, so total airframe cost is probably still in the $10 range, not counting the $6 wheels. In spite of my overbuilding and over taping, the Bee started out about 100 grams lighter than the Axon at 950g. It has a slower-turning motor, which is theoretically less powerful, but actually seems to produce about the same amount of static thrust, which I measured at 800g by holding the plane nose-down on the kitchen scale and opening the throttle. I have much to learn about electric motors and propeller sizing, but the Bee will have plenty of oomph. I mounted the motor high to protect the propeller and motor in crashes, but forward of the wing to concentrate the mass toward the nose. The Axon was really designed to carry a camera and extra radio gear in its nose for FPV flying, whereas the Bee is strictly intended as a line-of-sight RC plane, and concentrating the heavy parts should reduce the pendulum effect. I tapered the fuselage sections for looks and to reduce weight.
The winds have been relentless in Portland for the last week (no doubt related to the creepily warm temperatures), but the Bee finally flew on Friday, May 3, at our usual undisclosed location. We had driven to the spot a few days before, but I was scared to fly in the high winds, especially after the death of the Axon. On Friday, the winds were light, with occasional gusts. On the first flight, the Bee shot into the air and quickly climbed to about 75′. I turned it downwind, and realized that the plane was crazy twitchy in pitch and roll. I tried to steer it back, but soon gave up and just shut off the power to let it glide into a farm field. I’ve learned that the gentle crash is preferable to the hard “landing.” My decision to crash-land came after Guthrie said “um, Dad, the plane is upside down.” Oh, yeah. No damage in the crash, just let it sort of flutter into the weeds.
Realizing that we were seriously tail-heavy, I moved the battery as far forward as possible, put a small rock in the nose, and turned the ailerons down to 75% throws. Much better. Landed and put a couple of more small rocks in the nose. Beautiful. When we got home I weighed the rocks at 30g. When building the plane, I did all sorts of research about where to put the CG, but I was still a bit off. If I rebuild this plane or build another like it, I’ll know to put the lower fuselage further forward, with room to move the battery back and forth for fine tuning.
With nose weight, the Bee flew really well. It generally went where I pointed it, and kept its trim with power on or off. It quickly self-recovers from stalls, just let go of the sticks. Unlike our Axon, the Bee rolls without losing much altitude, which makes turns really easy. Very aerobatic, at least by my newb standards. The winds were really starting to gust by the end of our flying session, and the Bee did really well. It wants to float (and float, and float) on landing, even more than the Axon, so some sort of flaperons may be in the works.
I’m not sure that I can fly it in our local vacant lot, at least with my current skills. It’s a bit more forgiving and not quite as fast as the Axon, but the Bee covers a lot of ground quickly, and flies quite fast under power. It would be easy to lose it in a tree or on somebody’s roof. But maybe with more practice…