WL = Weight (oz) ÷ Area (sq ft)
WL = Weight (g) ÷ Area (dm²)
WCL = Weight (oz) ÷ Area (sq ft)1.5
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WCL Performance Category Chart
Wing Cube Loading places your model in a performance category — that classification comes from the airframe’s weight and wing area, not the motor. The motor’s job is to deliver on it. Once your WCL lands in a category, the power loading column tells you what the motor must produce per pound of aircraft to fly the way that category promises. The Your Power column translates that directly into watts at your specific weight — the number to bring to the motor spec sheet. Your matching category highlights automatically after you calculate.
| Category | WCL Range | Min. Power | Your Power | Flight Characteristics |
The non-highlighted rows also show “Your Power” values — what a motor would need to produce to push your airframe into those other envelopes. Useful if you’re considering a rewind, a different prop setup, or designing an airframe from scratch and haven’t locked in a WCL yet. Power figures shown are minimums: the floor for that performance level at your weight, not a cruise target.
Air density drops roughly 3% per 1,000 feet above sea level. At a mile-high field, your prop is working in air about 17% thinner than at sea level. The prop unloads — it spins faster and draws fewer watts than the same prop would at sea level. The goal is to restore that watt draw, not to compensate with more motor or more battery.
The right move: go up in prop size. A larger diameter, more pitch, or switching from a thin-electric style prop to a slow-flyer style (more blade surface area on the same diameter-pitch spec) all add load back to the motor — restoring the watt draw you had at sea level. There is no need to buy a bigger motor or a heavier pack. Doing so increases your wing loading and makes the altitude problem worse, not better.
One additional consideration: at altitude, your model stalls at a higher airspeed because the thinner air generates less lift per square foot of wing. In some setups, a modest increase in pitch speed is actually the right call — it keeps the model comfortably above stall while keeping the power system within its sea-level operating point.
A note on gas models (outside the scope of electric RC, but worth knowing): gas engines breathe. They consume oxygen as part of combustion, so thinner air at altitude directly reduces power output. Gas models must have their mixture leaned and prop down — reduced diameter with increased pitch — to let the engine run more efficiently in the thinner mix. Electric motors have no such constraint; they are unaffected by air chemistry. Only the prop’s aerodynamic load changes.
For a full walkthrough of altitude compensation in prop selection, see Propeller Matching — The Black Art Explained →