Estes Aero X
Capacitor Powered Free Flight Airplane
Website by Bill Kuhl
|
Estes Aero X Capacitor Powered Free Flight Airplane Website by Bill Kuhl |
|
Video Clip of Aero X flying Video Clip of Balsa Constructed Plane with Aero X Power Unit
 |
 |
|
| Aero X with Launcher / Charger | Aero X in Flight | |
 |
 |
Weight: 7.23 grams Wing Area: 21 square inches Wing Loading: .34 grams per square inch
Aero X is a small mostly foam plane powered by an electric motor that receives electrical energy stored in a capacitor. Three AAA cells in the launcher charger, charge the plane in seconds. Press the trigger and the plane is launched. This is a real help to beginners who tend to launch model airplanes too hard. Unlike, many RTF airplanes, the Aero-X is very lightweight - 7.23 grams. This makes for a plane that is safer and can take plenty of knocks without damage. So far I have only minor dings from flying indoors and outdoors. The motor is in a pusher configuration, which saves the prop and prop shaft from damage.
Think the biggest negative of the Aero X is there is too much camber in the wing, that is too much curve in the airfoil. This gives the plane too much lift and it stalls constantly. If you adjust the elevator with enough down to stop the stall, when the power reduces, the plane stalls severely. Most people add a small amount of weight to the nose, which helps. I experimented with cutting the trailing edge of the wing loose from the pylon and shimmed the back of the wing up by an eight of an inch. Another problem is the thrustline of the motor is angled so that at full thrust it keeps the nose down some, but as the power runs down, the stalling becomes very pronounced.
 |
Here is what the inside of the Aero-X looks like. The capacitor is in the front, connected directly to the charging / launching jack. Tiny motor in the back of the pylon. |
Building a Balsa Plane for Aero X Power Unit
Wing Area: 43 square inches Weight: 6.75 grams Wing Loading: .16 grams per square inch
When a stick and tissue model airplane modeler buys a ready-to-fly model plane, they almost always have in the back of their mind, someday they will take the power unit out of RTF plane and put it in a plane constructed of balsa. I was waiting for my Aero X to become really beat-up to cut out the power unit, but it was still in good shape after several months of flying. Instead I purchased another plane and cut the old one up.
The yellow piece of plastic contains a switch to keep the electric motor from getting power while you are changing the capacitor, this is also where the launcher attaches for charging. It would appear incorporating this unit in a new plane would be a good idea, which is what I did. By rounding the end of the balsa boom, the boom can fit easily in the rear part of the yellow plastic piece.
Wing and tail assemblies, I found all-built in my shop, apparently leftovers from other projects. The surfaces were covered with condenser paper, which is a pretty light covering material. For the new wing which is much wider, I mounted the electric motor on a pylon towards the front of the wing. With this arrangement, I did not have to add any additional wire to reach a rear-mounted motor and the weight was slightly ahead of the CG.
My new plane weighed almost 1/2 gram less than the Aero X, but had twice the wing area resulting in a wing loading that is half that of the Aero X. The airfoil has less camber (curve) my a large margin, which should result in less drag.
A Previous Experiment
In an attempt to improve the performance of my aging Aero X, I had added foam extensions to the wing constructed from foam plate material. Performance was disappointing, resulting in a flight that was no better, or possibly worse. My theory on this was adding the extra wing had increased the drag too much for the tiny motor and prop. This still might be true, but there was another factor that was contributing more to the anemic performance.
Flying the New Plane
The new plane flew well with only a couple of adjustments, increasing the incidence slightly (raised the front of the wing) and moved the CG ahead a slight amount. Flights were now very smooth with a gradual climb, and a very smooth transition into the cruise and the descent. Still the height obtained and the duration seemed a little disappointing to me.
The New Aero X
I decided it was time to bring out the new Aero X I had purchased and fly it for a comparison. In the back of my mind, I had thought my first Aero X had performed better when it was new. To make sure the battery condition in the launcher was not a factor, I used the old launcher for both planes. First flight of the new Aero X proved my suspicion, you could definitely hear the motor wind up much higher. After flying my new stable plane, I forgot how wild the flights of the Aero X could be out of the box. It did tight circles no more than a few feet in diameter, almost to the ceiling. The torque of the tiny prop spinning must be causing the tight turns, because when the power began to level off, the plane flew straight and eventually in the opposite direction.
 |
 |
| Original design balsa airplane using Aero X components. | Close-up of capacitor, switch, and motor. |
I am in the process of replacing the motor in this plane to see if performance improves. Check back for more updates.
Ultracapacitors Might Replace Batteries
MIT electrical engineer Joel Schindall thinks the time is ripe for capacitors. “They are better than batteries in almost every way, except in the amount of energy they store.” The research group led by Schindall thinks they have conquered that limitation.
References:
Discover Magazine Technology Review PC World Electronic Products
Bill Kuhl
Articles About Capacitors
http://www.uoguelph.ca/~antoon/gadgets/caps/caps.html
http://www.interq.or.jp/japan/se-inoue/e_capa.htm