Airframe
Ruby will work with just about any fixed wing airframe including flying wing, glider, sport, and trainer.
How small?
A complete Ruby system weighs about 25 grams.
The main constraint for very small planes is usually not weight, but the size of available payload/cockpit area. Ruby's main controller is 3 x 1 x 3/8''. It is possible to mount the controller outside the fuselage, however.
Our quick and dirty rule of thumb for small electrics: if the manufacturer recommends 450mah battery or larger, it's probably big enough for Ruby.
How large?
There's no theoretical limit to the size of model that Ruby can fly. To date, Ruby has been tested in planes weighing up to 6 pounds.
Gas, Turbine, or electric?
Ruby should work find in any aircraft regardless of propulsion. Ruby has been tested extensively in electric powered planes, but has had only limited testing in gas powered planes. We plan to complete full beta testing in gas planes by end of Spring 2014. Please contact us if you're interested in using Ruby in turbine powered aircraft.
Input Power
Ruby requires 4.5- 5.4 volts input, with 5.0 to 5.2 volts most ideal.
Higher voltages can permanently damage Ruby. Lower voltages may cause inaccurate sensor readings, erratic behavior, and ultimately unpredictable shutdown.
Ruby with the Expander and various future add-ons will draw about 180ma to 250ma of continuous power. For comparison, remote control receivers typically draw from 10 to 80ma, although some with more advanced features can draw nearly 200ma.
For Electric planes with "ESC"s:
Most Electric Speed Controls (ESC) have a Battery Elimination Circuit (BEC) built into them that provides 5 volts needed by electronics and servos. Note that while ESC manufacturers typically rate the BEC's built into their ESCs at high amperages (typically 1 to 5 amps), this rating is usually for *peak* surges typical when driving servos, not for continuous power. It's like the difference between using your car's brakes in normal stop and go traffic, and riding the brakes down a long hill.
Some ESCs such as the E-Flite "30-Amp Pro Switch-Mode BEC Brushless ESC" can easily handle 700ma of *continuous" output power, making them ideal.
We're told by Castle Creations that the BEC on all but perhaps their small 6 and 9 amp ESCs should be able to provide 250mah continuous power without a problem. It makes us a little nervous however, because they (and most ESC manufacturers) use a "linear" BEC rather than "switching" BEC, and the voltage difference is essentially converted to heat.
Continuous power ratings for other brand ESCs are not known to us at this time.
If in doubt, we recommend using a separate "switching BEC" (see below).
For non-electric planes:
We also recommend but don't require the use of a switching BEC in conjunction with a small 2 or 3 cell lipo battery instead of wiring directly to a standard NiMH flight pack. This will give longer flight time with a reliable constant ideal 5.0 volts.
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