Stats & Formulas

How the builder calculates drone performance from your component selections.

📦 Total Weight

totalWeight = frameW + motorW×4 + escW + fcW + camW + vtxW + rxW + vtxAntW + rxAntW + propW + hdwW + batW

Component weights come from each product's weight_grams field in the database. Motors are multiplied by 4. hdwW is a hardware overhead (screws, wires, tape) estimated at ~15g for analog builds, more for digital.

⚡ Motor RPM

rpm = kv × voltage × 0.85

The 0.85 factor accounts for real-world voltage sag under load (85% of theoretical no-load RPM). Voltage = cells × 4.2V (peak).

kv = Motor KV rating
voltage = Battery cell count × 4.2V

🚀 Max Speed

pitchSpeed = rpm × pitch(in) × 0.0254 × 60 ÷ 1000

maxSpeed = pitchSpeed × loadFactor

Pitch speed is the theoretical speed of the prop's helical path. A load factor reduces it for real-world aerodynamic losses. Speed is capped based on prop size (e.g. 180 km/h for 5").

pitch = Prop pitch in inches (defaults to ~80% of prop diameter if unknown)
loadFactor = 0.65 for 5"+ props, 0.5 for 3", 0.55 for 4"
speedCap = 180 for 5", 110 for 3", 150 for 4"

💪 Power / Weight Ratio

maxPowerW = escAmps × voltage × 4

powerToWeight = maxPowerW ÷ totalWeight(kg)

Uses ESC current rating as the power limit (conservative). If motor stator size suggests lower max draw, the lower value is used.

motorAmps(22xx) = 22A per motor, motorAmps(23xx) = 26A, motorAmps(24xx) = 30A

⏱️ Flight Time (Hover)

hoverWkg = W/kg required for hover (by prop size)

hoverW = totalWeight(kg) × hoverWkg

flightTime = usableWh ÷ hoverW × 60

Hover power per kg depends on prop efficiency. Smaller props need more power per gram (higher disk loading).

hoverWkg = 280 for 3", 220 for 4", 200 for 5", 180 for 6"
usableWh = capacity(mAh) ÷ 1000 × voltage × 0.8 (80% usable)

🔄 Cruise & Full Throttle Time

cruiseTime = flightTime ÷ cruiseFactor

fullThrottleTime = flightTime ÷ ftFactor

cruiseFactor = 1.25 for 3", 1.30 for 4", 1.35 for 5-6", 1.40 for 7"+
ftFactor = 1.7 for 3", 2.0 for 4"+

🛩️ Thrust-to-Weight Ratio

maxThrustG = maxPowerW × gramsPerWatt

thrustToWeight = maxThrustG ÷ totalWeight

gramsPerWatt = 4 for 5"+ props, 3.5 for 3-4", 2.5 for 2-3"

🏅 Ratings (Build Score)

speedRating = maxSpeed ÷ 22 (capped 1-10)

powerRating = powerToWeight ÷ 400 (capped 1-10)

efficiencyRating = flightTime ÷ 1.5 + aeroScore ÷ 3 (capped 1-10)

buildScore = (speedRating + powerRating + efficiencyRating) ÷ 3

aeroScore = based on frame size (3"=7, 4"=6, 5"=5, 6"=4, 7"+=3) ±1 for weight