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The build calculator.

Pick a motor, a propeller, and a battery. Adjust payload and altitude. The calculator outputs all the metrics from the combinations catalog — T:W, hover throttle, top speed, flight time, payload margin — for any combination, including ones not in the catalog. Real-world numbers corrected for typical Mindanao field conditions.

Version 1.0 · Updated 05·2026 Author: Lumipad Engineering License: CC-BY-SA-4.0 Languages: EN
14
Motors in database
12
Propellers in database
11
Batteries in database
~1,800
Possible combinations
How this works

Pick three components, see the flight envelope.

The calculator combines manufacturer thrust data (for motors at specific voltages) with the physics from the thrust deep dive. The motor entries contain measured thrust at the manufacturer's recommended cell counts; props and batteries contribute to weight, current draw, and energy capacity. Outputs include both spec-sheet (best case) and real-world (Mindanao-corrected) values.

The calculator is honest about its limits. Predictions are typically within ±15% of measured flight data — fine for design decisions, not fine for safety-critical margin calculations. If a result says T:W is 2.1, treat it as "1.9 to 2.3 in practice." Use this tool for narrowing options; verify with a brief test flight before committing to a fleet build.

Build calculator

Configure your build.

Pick a preset to start from a known-good combination, or build from scratch. The output panel updates immediately as you change selections. Warnings appear when a combination violates known rules (motor voltage limits, T:W floor, etc.).

Frame

Motor

Propeller

Battery

Environment & payload

95 g
Sensor weight beyond the standard NDVI rig (95g default).
50 m
Davao city ~50m. Bukidnon plateau ~600–1,200m. Mt Apo summit 2,950m.
30 °C
Mindanao midday averages 30–34°C. Reference is 15°C.

Flight envelope

T:W spec
T:W real
Hover %
km/h max
min flight
Add'l payload

Build summary

All-up weight
Static thrust (4 motors, full)
Hover power per motor
Battery energy
Air density (your conditions)
Approx component cost

Warnings & notes

  • Pick components above to see warnings and recommendations.
How to read the outputs

Six numbers worth understanding.

What each output means and how to interpret it. The calculator presents these as a single grid; reading them as a system tells you whether a build will fly the way you want.

T:W
Spec vs real
Real is ~75-80% of spec
~30%
Hover throttle target
Below 45% is good
v_max
Drag-limited
For survey, cruise lower
t_min
Cruise flight time
~85% of battery Wh
PAY
Additional payload
Above current selection
±15%
Predicted vs measured
Verify with test flight
Worked examples

Using the calculator for real decisions.

Four practical scenarios, with the inputs to set and what to watch in the outputs. The calculator is most useful when you're using it to compare two or three options against each other rather than evaluating a single combination in isolation.

"Should I buy the 4S 1500 or the 4S 1800 battery?"

Battery sizing question

Load preset 5A. Note the flight time and T:W. Then change battery to "CNHL 4S 1800mAh 75C" (preset 5B's battery). Watch what changes: weight goes up ~35g, T:W drops slightly, hover throttle climbs ~3pp, but flight time gains 1.5–2 minutes. The 1800mAh wins if your missions need extra time and you don't fly aggressively; the 1500mAh wins for agility.

"Will my build fly at the Bukidnon plantation (1,000m)?"

Altitude question

Load your build (e.g. preset 5A). Slide altitude from 50m to 1000m. Watch real-world T:W drop ~10% and hover throttle rise ~3pp. If T:W is still above 2.5:1 and hover throttle stays under 45%, you're fine. If T:W drops below 2:1, switch to a higher-thrust combo (5C or 5I) before going.

"What if I add a 200g multispectral camera?"

Payload question

Slide the payload from 95g (default NDVI rig) to 295g (NDVI + multispectral). The hover throttle and flight time should stay reasonable for 7-inch builds; for 5-inch, you'll usually see hover throttle climb past 45% and flight time drop sharply. If hover throttle is above 50%, the 5-inch can't take the payload comfortably — go to 7-inch.

"How much does a custom prop change things?"

Prop tuning question

Load preset 5A. Switch prop from 5×4.3×3 to 5×5.0×3 (the aggressive option). Watch top speed climb, T:W drop slightly, flight time drop ~15%. The change isn't free — higher pitch means higher current draw at the same throttle. Useful when you specifically need top speed or wind tolerance; otherwise, stay with the lower pitch.

Frequently asked

Questions worth answering carefully.

How accurate are the calculator's predictions? +

Predictions are typically within ±15% of measured flight data for in-database combinations. For combinations close to the catalog presets (where we have actual flight log data), accuracy is closer to ±10%. For unusual or extreme combinations, accuracy degrades — the underlying physics holds, but the empirical corrections may not.

If a calculator output says "T:W is 2.8:1 spec", the real-world value will likely fall between 2.0:1 and 2.4:1 in field conditions. If it says "flight time 6.5 minutes", the actual flight will likely fall between 5.5 and 7.5 minutes depending on wind, payload movement, and pilot inputs.

Use the calculator for design decisions and screening; verify with a brief test flight before committing to a fleet build or a production mission.

Why do calculator outputs sometimes disagree with the catalog? +

For combo 5A (the cohort default), the calculator and catalog agree closely — within ±5% on weight, T:W, hover throttle, and top speed. For some 7-inch and 10-inch combos, the numbers diverge.

The reason: the catalog was assembled before this calculator was built, and some catalog rows used real-world performance figures labelled as "spec" rather than computing both spec-sheet (theoretical) and real-world (corrected) numbers separately. The calculator computes both honestly.

For example, the catalog's "7A T:W: 2.8" reflects what alumni actually measure in field conditions; the manufacturer's published thrust data for that motor combination would imply a spec T:W around 6:1. The calculator outputs the latter as "T:W spec" and the former as "T:W real".

We're updating the catalog rows to align with calculator outputs (showing both spec and real explicitly) in the next library revision. For now: trust the calculator's relative comparisons across combinations more than the absolute numbers, and treat the catalog's published numbers as already real-world-corrected.

What is the calculator NOT modeling? +

Several real-world effects are simplified or ignored:

  • Pilot inputs — the calculator assumes steady cruise. Aggressive flight, sharp manoeuvres, and recovery from gusts all consume more energy than steady cruise.
  • Wind — assumes calm conditions. Wind requires the drone to fight forward thrust constantly, which costs power. Add ~10% power consumption per 5 m/s of wind.
  • Battery age — assumes a fresh, mid-life pack. Old packs have higher internal resistance, more voltage sag, and lower usable capacity. Subtract 10–20% of flight time for packs above 100 cycles.
  • Frame-specific aerodynamics — uses a generic drag model per frame size. Specific airframes (especially racing frames or specialised research builds) may have very different drag characteristics.
  • Motor efficiency variations — uses simplified curves. Real motors have efficiency peaks at specific RPM ranges; the calculator approximates this as a single ~60% efficiency at hover.
  • FC, RX, FPV, sensor power draw — folded into the cruise factor, but for builds with unusual sensor packages, you may need to add 5–15W to the per-motor power estimate.
What if my motor or battery isn't in the database? +

The database includes the components used across the 26 catalog combinations plus a few common alternatives. If your specific motor or battery isn't there, pick the closest analogue:

  • For motors — match by stator size and KV. A "BrotherHobby Avenger 2207 2400KV" behaves nearly identically to "EMAX RS2207 2400KV" — pick the latter as a proxy.
  • For props — match by diameter, pitch, and blade count. Material differences (PC vs nylon vs CF) make small differences mostly captured by weight; pick the closest sized PC option.
  • For batteries — match by S, mAh, and C-rating. Brand differences mostly affect longevity, not flight performance.

For combinations that diverge significantly from the database, calculate weight from your specific component spec sheets and use the calculator's outputs as a starting point — then test-fly to verify. The thrust deep dive shows you how to do the calculations from first principles.

Why does the cost estimate seem off? +

The calculator's cost estimate is rough. It includes motors, props, battery, frame, FC, ESC, RX, and basic FPV gear — but not: NDVI rig, antennas, upgrades to FC/RX, transport cases, batteries beyond the first one, or any spares. For real procurement planning, expect 30–50% more than the calculator shows.

The catalog rows in the build catalog include more accurate end-to-end costs that account for these additional items.

Why does the calculator default to combo 5A? +

It's the most common cohort build and a reasonable starting point for understanding the tool. Once loaded, you can either tweak from there (change one component at a time to see how each affects the output) or load a different preset to start from a different baseline.

If you'd like a different default, the URL bar can preserve state — bookmarking a configuration is on the roadmap. For now, "Reset to default" returns to 5A; pick from the preset dropdown to load any other catalog combination instantly.

Can I download or export the results? +

The XLSX version (downloadable from the link at the top of this page) has the same calculation engine running in Excel/LibreOffice with extended capabilities — multiple builds compared side-by-side, mission planning across multiple flights, fleet-level cost rollups. Use the in-browser version for quick scenarios; use the spreadsheet for fleet planning.

For sharing a specific configuration with another alumnus or partner org, screenshot the calculator's output panel — that captures the key flight envelope numbers in one image.

Why are some preset combinations from the catalog not in the dropdown? +

The preset dropdown includes combinations whose specific components are in the calculator's database. A few catalog combinations (5H indoor cinematic, 5I high-altitude, 5K dual-cell, 7E agricultural carbon, 7F BVLOS-ready, 7H premium carbon, 10D budget, 10F hexacopter) use parts that aren't in the database yet.

For these, you can usually approximate by picking the closest preset and adjusting one component at a time. We'll add them to the database in the next calculator update — Q3 2026 alongside the spreadsheet release.

Is there a way to compare two configurations side-by-side? +

Not in the in-browser calculator yet. The intended workflow: open this page in two browser tabs, configure one in each, and compare the output panels visually. That works fine for quick A/B comparisons.

For more than two configurations, the XLSX version is purpose-built for side-by-side comparison — its "multi-build comparison" sheet lets you configure up to six builds and shows their outputs in a single grid. Designed for fleet planning at partner-org scale.