Setup too marginal — 15 s peaks, headroom and red gauges

A setup that “just hovers on paper” can destroy a motor, ESC or pack on the first windy punch-out. eCalc colours peak current/power and temperature because manufacturer limits are often short-duration — help text frames this around up to about 15 s. Continuous flight needs headroom.

What “too marginal” looks like

Typical signals in xcopterCalc / propCalc:

• Power/Current gauge yellow to red
• est. Temperature stuck yellow/red
• Battery Load in peak or over-limit
• Hover throttle already high → no manoeuvre margin (Sizing)
• Thrust-to-weight barely above 1.2

Blue = advisory, red = critical — not UI bugs.

Mechanism: peak vs continuous

Windings and ESC FETs tolerate brief overload better than minutes at the same amps. Flying race punch-outs as normal forward flight treats peak as continuous. ESC ratings often assume good airflow and full-on conditions; help suggests extra margin for poor airflow (~20 %), convection (~40 %) and partial load (~20 %) — rules of thumb, confirm with temperature.

Packs: C-rate has continuous and peak bands. See LiPo sizing and Overheating.

Headroom rules of thumb

1. Hit mission hover targets (article 01 table).
2. Budget peak amps for short manoeuvres only.
3. Upsize ESC when cooling is mediocre.
4. Keep continuous C in green; touch peak rarely.
5. Clear red gauges before buying.
6. Avoid excessively long ESC power leads — still a classic ESC killer per help.

Worked example: “hovers, kills ESCs”

Assumptions:

• 5” quad, AUW 750 g, 4S 1500 mAh “80C” marketing pack
• Props 5×4.8, motors at the high end of Kv
• Hover ~55 % (explorer-OK) but max current red, temperature yellow, load yellow

Fixes to re-simulate:

1. Prop 5×4.3 / 5×4.
2. Lower AUW.
3. Higher-rated ESC + airflow.
4. More honest continuous-C pack.
5. Re-run Prop-KV-Wizard (Kv vs prop).

Steps in eCalc

1. Enter the setup in xcopterCalc (or propCalc).
2. Read all gauges: Load, Temperature, Power/Current, T/W.
3. Change one thing, recalculate.
4. Goal: hover in mission band, peaks only briefly yellow, case temp not sustained above ~80 °C.
5. Verify on the bench.

More practice: pre-purchase checklist

Before you order motors or ESCs:

1. Hover throttle inside the mission band?
2. Peak gauge not stuck red?
3. Temperature estimate OK with realistic cooling?
4. Pack load green/yellow for continuous use?
5. Wiring planned short and thick enough?

If more than one item is “tight”, the setup is too marginal — regardless of what a video runs. eCalc aggregates physics and part limits; forum luck is not headroom.

The same logic applies in propCalc for airplanes: climb is often closer to continuous load than people admit.

FAQ

Green in hover, red at max — OK?
For rare punches often yes; for sustained climb/wind fighting no. Be honest about the mission.

Why does the ESC die first?
PWM losses, heat, long wires, peaks without margin.

Need membership?
Demo is fine to learn; full DB/export help serious comparisons — see signup.

After a failure

If an ESC or motor already died: rebuild the setup in eCalc before ordering 1:1 replacements. The layout was often the cause. New parts alone without changing prop/Kv/cells repeats the failure. Keep gauge screenshots for learning and club discussion.