The airframe spec only states takeoff mass, endurance and similar targets; the cell datasheet only gives measured C-rate and energy-density curves — and the conversion that joins the two is written down nowhere. eVTOL Battery Estimator makes it a chain you can re-run and audit.
Why this step is hard
SC-VTOL states the margin; a datasheet states the measured curve. The step that turns aircraft parameters into “how many W/kg and how much C does the cell need” has no tool and no formula book — it is judgement built from programme experience.
Usually worked by hand by a chief designer or powertrain lead who has taken a full programme through. Without that person the project stalls here — not for lack of will, but for lack of a convention to compute with.
Give two engineers the same aircraft numbers and their assumptions diverge — answers can land 20% apart. In review everyone sounds right; nobody can be checked.
Ten parameter changes a day is normal. Each one means recomputing thresholds, re-ranking candidates and redrawing curves — the hours an engineer can least afford to lose.
Six capabilities
Not just a number: derivation, comparison, inverse questions and the write-up all share one convention.
Enter mass, thrust-to-weight, rotor efficiency and battery mass fraction; get required power density, required C-rate and hover endurance — with every assumption listed in the report.
The step only a few engineers can do, now a process the team can re-run
Effective power density is esp × continuous C-rate, with pass / marginal / fail verdicts at a 10% margin.
One verdict convention — results are comparable across engineers
Hold everything else fixed, sweep one variable (efficiency, mass fraction, T/W) and see its effect on the threshold.
Which parameter dominates the design space — answerable
Given what the cell can actually deliver, solve for the minimum mass fraction, maximum T/W and minimum rotor efficiency.
From “does it work” to “which way to move the parameters”
Change any input and the three results, candidate verdicts and curves refresh together — no second spreadsheet.
Time goes to judgement, not to recalculation
One-click PDF (inputs, derivation, comparison, curves, conclusion) or CSV; SI internally, metric or imperial on screen, Chinese and English sharing one convention.
Review material written for you, fully traceable
No network requests, no telemetry, no design data leaves the machine. Deployable in restricted, defence and air-gapped environments; licence checks run locally with no activation server.
Design baselines
Parameters from typical configurations. Each card is the full output of the same chain: what the cell has to reach in that airframe.
The three figures are: required power density · required C-rate · hover endurance limit.
600 kg class passenger configuration and the default preset — a quick check on whether current cells can carry hover power.
1.5 t class with conservative rotor efficiency and mass fraction — the risk upper bound for early concepts.
80 kg class platform: higher mass fraction, lower T/W, matching light commercial airframes.
2 kg class platform: highest efficiency and mass fraction, typical of small multirotors.
Interface and reports
Fixed two-column layout: inputs stay put on the left while results and the candidate table scroll independently.
Who it is for
Licensing
¥600 per licence, one device. Activate locally with a key — no network afterwards, no subscription, no expiry.
One-time payment. Activates locally and keeps working.
Buy licenceWindows 10 / 11 · 76 MB single file · no installer. Enter your licence key on first launch, then work offline indefinitely.