EASpec stands for Electric Aircraft Specification, and is a new iPhone / iPad app. It is intended to make it simple for anyone assembling an electric powered model aircraft to correctly specify a set of equipment that will deliver the intended flying performance.

Electric motors, speed controllers and Lithium Polymer batteries are now abundant, but the problem for any modeller is "how to select the right equipment?". Some people only use the exact equipment recommended by the manufacturer, but this is highly restrictive, with the recommended components possibly unavailable locally, or only available at high cost. A better approach is to utilise this application, where the modeller enters an estimate of the aircraft's weight, the intended flying style (from mild to WILD!), and the target flight time, then the app advises the specifications for the motor, speed controller and battery. The user then looks for equipment approximating these specifications from whichever supplier they choose, with a high degree of confidence that the result will work exactly as intended.

$1.99 from itunes: https://itunes.apple.com/au/app/id578943977?mt=8

Happy specifying and flying!
EASpec

Note that the power drawn by an electric motor is highly dependent on the selected propeller. The app makes its recommendation on propeller size on the proviso that the motor Kv and resistance are accurate, but manufacturers sometimes struggle to accurately report these figures.

It is recommended that the user employs a watt meter to confirm the selected propeller achieves the target power (which the app advises). If the measured power is lower than intended, a larger propeller should be installed and the power test repeated, and vice versa.

Sample aircraft spec #1
Top Flite Mustang 60 ARF

Here's the airframe: http://www3.towerhobbies.com/cgi-bin/wti0001p?I=LXTDF5

The completed plane used the following equipment:

• Motor: Turnigy Aerodrive SK3 - 5065-320kv
• ESC: Turnigy dlux 120A HV Brushless Speed Control
• Batteries: Rhino 8S (4S x2) 3700mAh 30C
• Prop: Turnigy Ultra-light wood propeller 15x10

Peak power was 1600W, with impressive performance. Excellent aerobatic capability (as expected). Takes-off easily at about half throttle, and has enough power to fly almost unlimited vertical. The 10-inch pitch allows for easy slow flight at about 40% throttle, which is very scale-like but has enough pitch speed at low rpm to maintain flight speed.

Note that the 120A ESC was selected simply because the user had one. Peak current is only 57A, so a 70A - 80A ESC would have been adequate.

Sample aircraft spec #2
R2 Hobbies Passer-X "Warmliner"

Here's the airframe: http://www.r2hobbies.com/rc-aircraft...ilplane-2.html

The completed plane used the following equipment:

• Motor: KD A22-20L
• ESC: Turnigy Plush 30A ESC
• Battery: Rhino 3S 1050mAh 30C
• Prop: Graupner 11x8 folding prop

Peak power was 270W, with fast vertical climbs to 500+ft in ~15 seconds. The 2.5mins motor run time gives a LOT of climbs to altitude, with one flight lasting over 1 hour.