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Glow to Electric Conversion calculator

Glow to Electric Conversion Power System Calculator

The methods and "rules of thumb" that are used here were taken from an excellent conversion article written by Jim Bourke, and published on the E Zone. The article appears at http://www.ezonemag.com/articles/1997/cdancer/cdancer.htm.

Step 1: Determine Weight Goal

The target weight should be determined using the Wing surface area, and the desired loading based on the type of aircraft.

Wing Loading
LoadingType
10 oz/sq.ftGlider
15 oz/sq.ftTrainers
20 oz/sq.ftSport Plane
25 oz/sq.ftFighters

Aircraft Wing Area sq. inches
Desired Wing Loading oz/sq.ft
 
Weight Goal oz
pounds

Step 2: Determine Power Goal

The next step is to determine the desired performance level. There is a rule of thumb we use for this called "watts per pound". The basic idea is that the general performance characteristics of a model can be predicted as follows:

Performance Level
Watts per poundPerformance Potential
< 50 watts per poundUnable to rise off ground
50 to 60 watts per poundCan rise off ground and perform simple aerobatics
60-75 watts per poundEasily loops from level flight. More impressive aerobatic performance.
75-100 watts per pound"Fighter"-like performance. Aggressive climbs
100-150 watts per poundExtended vertical runs. Unlimited aerobatics
> 150 watts per poundWings are unnecessary

Desired watts per pound watts per pound
 
Power Goal watts

Step 3: Determine Current (amps) Goal

The next step is to determine the desired current draw. This is done based on the battery cell capacity, and the desired duration:

Note: This calculator does not attempt to determine if the target current is appropriate for your desired electric motor.

Planned cell type
Desired full-throttle duration minutes
 
Current Goal amps

Step 4: Calculated required number of battery cells

This number of battery cells required is determined based on the Power Goal and the Current Goal. Volts = watts / amps. Each cell effectively provides approximately 1 volt, so we need 1 cell per needed volt. Based on the number of cells, we can also determine the approximate weight of the battery pack:

Required number of battery cells battery cells
Battery pack weight oz.

Final Step: Calculate target weight of aircraft without battery packs

Now we can determine how much the aircraft should weight without the battery packs. This should be very close to the weight of the glow-powered aircraft.

Target weight without battery pack oz
pounds