A BASIC GUIDE TO SUCCESSFUL
ELECTRIC FLIGHT

The penalty (there had to be one) in the last example given above is of course weight, the weight of the gearbox and especially the extra cells. Model design for electric flight must be efficient in it's use of materials, years of designing I/C engined power models has done little to develop the art of the light but strong structure. Perhaps the most important parts of an electric powered model are those parts which were 'designed out'.

Designers have understandably therefore found inspiration for small (SPEED 400) electric models by going back to our aeromodelling roots of rubber powered scale models. Take a look at a Peanut Scale rubber model, an Earl Stahl scale design or even a Keil Kraft rubber scale job, mentally enlarge it to 36 or 40 inch wing span and you have the basis of a strong and light electric model. Add a little nose sheeting and some structure to hold the radio control equipment and flight battery in place, an access hatch or two and you are nearly there. What you will find you have not got is excess weight.

If you are building a Graham McAllister Designs kit take note of the use of materials, they are much lighter than you will be used to if you have come from I/C power, please do not be tempted to beef up the structure, such a model will only hit the ground harder. As you progress in electric powered flying look for kits or plans that are designed specifically for electric. I/C powered designs can be converted to electric, but be aware that reducing wood sizes and cutting lightening holes will lighten, but may also weaken a structure which could have relied on those large wood sizes for its strength rather than careful structural design. Much of the wood in an I/C design is incorporated to absorb the unavoidable vibration caused by the power plant, we do not need the thick nose sheeting and 6mm plywood fire wall. Conversions can become so extreme that a complete new design based on the original outlines could be quicker and certainly lighter.

Electric motors and batteries are heavy, too heavy, but we have to accept that and save weight elsewhere. After the structure of the aircraft radio control equipment is an obvious place to look. Mini servos are significantly lighter than standard size servos, micro are lighter still and no longer expensive. Micro receivers will save a little weight in a SPEED 400 size model but have little effect on the SPEED 600 size. A speed controller with BEC is the best weight saving investment, being light in itself and saving the relatively huge weight of a receiver battery.

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