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Calculators

The Formula Card's equations, live. Every calculator opens with the reference build's numbers already filled in, so the first answer you see is one the handbook has already derived by hand — change any field and watch the consequences. Nothing here leaves your browser.

Thrust-to-weight & hover throttle​

TWR=Tmax/(m g)\text{TWR} = T_\text{max}/(m\,g) and throttlehover≈1/TWR\text{throttle}_\text{hover} \approx \sqrt{1/\text{TWR}} — derived in Module 2. Thrust figures come from your motor's thrust table (bench values are an upper bound).

Thrust-to-weight9.2right in the freestyle 8–12 band
Hover throttle≈ 33 %

Flight time​

E=Vnom ×E = V_\text{nom}\,\times Ah, 80 % usable, t=0.8E/Pt = 0.8E/P — the honest math from Module 6. Hover for the reference build is ≈ 122 W; freestyle averages 2–3× that, which is the entire mystery of "why do I only get 4 minutes".

Pack energy28.9 Whof which ~80 % is usable if you land at 3.5 V/cell
Flight time≈ 11.4 minat this power — freestyle averages 2–3× hover power

FSPL plus gains against sensitivity — Module 1's core calculation. The default sensitivity (−108 dBm) is ELRS 2.4 GHz at 250 Hz; drop the packet rate and sensitivity improves (see the receiver page). Treat the margin pessimistically: misalignment, shadowing and Fresnel intrusion spend 10–20 dB of it in the real world.

Free-space path loss106 dB
Link margin26 dBcomfortable — real-world losses still leave headroom

Pitch speed​

v=RPM×pitchv = \text{RPM} \times \text{pitch} with a loaded-RPM factor — Module 5's worked example. Remember what this number is: a hard upper bound, useful for comparing setups, never a speed you will see.

Loaded RPM32,722
Theoretical pitch speed≈ 232 km/ha hard upper bound, never a prediction — prop slip alone costs 30–50 %
Where the formulas come from

Each section links to the module that derives it, with the same reference numbers worked by hand. If the calculator surprises you, the module is the place that explains why.