Al Clark's Mysterion - 2015/01
BUILD YOUR OWN INEXPENSIVE AEROBAT
by Al Clark
The Mysterion was designed in response to a request from my brother, Rod, who has flown several of my lightweight park-flyer designs. Rod has access to a large, well-manicured grass field and wanted a slightly larger model that would excel at aerobatics and be able to handle the wind. When designing the Mysterion, I spent much time trying to come up with the best combination of weight, size, aerodynamics, and equipment. I believe the result hits the sweet spot.
I incorporated everything I’ve learned from my previous designs into the Mysterion. The motor, wing, and stabilizer are all on the thrustline as well as the vertical center of gravity; the model balances perfectly on the spinner if it is positioned vertically on its nose. The fuselage is thin with ample side area and the canopy is placed well forward, which provides good knife-edge flight and good tracking in maneuvers.
The wing uses the Eppler E168 symmetrical airfoil section, which has a wide speed range, is well behaved at slow speeds, and refuses to tip stall while performing excellent snap rolls and spins. The wing has no dihedral—making inside and outside maneuvers similar. The rudder area is large, providing good control in knife-edge flight and making hammerhead stalls easy.
I incorporated features to make the model convenient to fly and transport. The wings attach using a carbon-fiber tube, a 1/16-inch music wire pin, and two 10-32 nylon thumbscrews. Easy wing removal makes the Mysterion convenient to transport in any small vehicle. The propeller is an Aeronaut folding 10 x 6—allowing grass landings without worry of breaking expensive props and reducing drag when the motor is off to improve the glide. The BB Model Turbo spinner unit does a great job of introducing cooling air to the motor and battery. The fuselage top—from the rear edge of the canopy forward to the motor cowling—is removable and uses magnetic attachments for battery and radio access.
The finished airframe is sanded and ready to be covered. The canopy is glued on after covering.
Power System, Radio, and Servos
- Motor: E-flite 480 brushless outrunner, 1,020 Kv, mounted to F1 using 1/4-inch diameter x 9/16-inch long 4-40 threaded circuit board standoffs (other standoffs will work as long as the length is 9/16 inch).
- ESC: Castle Creations Thunderbird 36-amp ESC.
- Battery: Thunder Power 3S 2,700 mAh Pro Lite 25C LiPo.
- Propeller: Aeronaut 10 x 6 folding propeller.
- Spinner: BB Model Turbo spinner for cooling.
- Servos: JR DS290G digital servos on the ailerons; Hitec HS-5065MG digital servos on rudder and elevator.
- Linkages: Short aileron pushrods and stiff carbon-fiber rudder and elevator pushrods for precise control inputs.
- Receiver: Spektrum AR6200.
The finished model weighs 36.7 ounces. With the Thunder Power 3S 2,700 mAh battery, flight duration is approximately eight minutes at generally full throttle.
Mysterion Specifications
- Type: Electric sport model
- Wingspan: 47 inches
- Wing area: 400 square inches
- Weight: 36.7 ounces
- Wing loading: 13.2 ounces per square foot
- Power system: 200–300 watt brushless motor; 36-amp ESC
- Propeller: 10 x 6 folding
- Battery: Three-cell (3S) 2,700 mAh LiPo
- Radio: Four-channel; four micro servos
- Construction: Balsa and plywood
Flight Characteristics
When it comes to aerobatics, the Mysterion performs better and more precisely than any of my previous designs. It does exactly what you tell it to do—no more and no less. It rolls as if on a string. Outside maneuvers look as good and are as easy to perform as inside maneuvers. Snaps and spins, both inside and outside, immediately stop when the sticks are released. Vertical performance is excellent; you must reduce throttle to perform hammerhead stalls. Knife-edge flight requires only a small amount of down-elevator mix (no more than 5%).
Slow-flight performance is outstanding with the Eppler E168 airfoil. If you didn’t know better, you’d swear the model had a semisymmetrical airfoil when flying slowly—the Mysterion happily flies around with complete control and refuses to tip stall. With the power off, the Mysterion has a flat glide because it is clean; it’s fun to give it a little altitude, shut off the motor, and perform dead-stick aerobatics.
The Mysterion is a great all-around model: relatively inexpensive to build, small enough to fit in nearly any vehicle, large enough to be visible in the sky and handle some wind, and with excellent flight performance. In my more than 40 years of model designing, it is my best effort.
Flying
Before you head out to test-fly the aircraft, double-check the balance point, control directions, and inspect for any warps caused by covering. It’s easier to correct these in the shop than at the field.
The control throws shown on the plans result in a fairly responsive aircraft. If you prefer softer controls or a slower response, set up dual rates and start with somewhat reduced throws.
Because the power-off glide is excellent, you may need to adjust your approach technique—make your turn to final approach farther out or lower than you are used to. I think you’ll find the Mysterion a pleasant model to fly; it is capable of any pattern maneuver as well as sport aerobatics, upright or inverted.
I hope you enjoy flying your Mysterion. It is compact enough to keep handy in your car and rates high on the "fun-per-buck" scale.
—Al Clark [email protected]
Sources
- AMA Plans Service
(800) 435-9262, ext. 507 www.modelaircraft.org/plans.aspx
Transcribed from original scans by AI. Minor OCR errors may remain.
