# Rocket Calculator: ApogeeField — Apogee, delay, rail-exit calc

> Apogee, delay, rail-exit calc (iPhone/iPad app by 毅 王.)

- Source: https://appshunter.io/ios/app/rocket-calculator-apogeefield/id6778329350 (this page in markdown: same URL + `.md`)
- Developer: [毅 王](https://appshunter.io/developer/6774631380)
- Category: Utilities, Education
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: English
- Released: 2026-06-12
- Data updated: 2026-07-06
- User reviews in markdown: https://appshunter.io/ios/app/rocket-calculator-apogeefield/id6778329350/reviews.md

## What is Rocket Calculator?

ApogeeField is an offline flight calculator for low and mid-power model rocketry. Enter your rocket (dry mass, body diameter, drag coefficient, launch-guide length) and pick a motor, and it predicts your apogee, the best ejection delay, max velocity, and rail-exit velocity right at the pad — with no signal, no account, and no tracking.

WHAT IT DOES
- Apogee, max velocity and full altitude / velocity / acceleration flight curves — free.
- Recommended ejection delay: ideal coast time mapped to the nearest delay you can actually buy, with the offset in seconds.
- Rail-exit velocity with a configurable safety threshold, so you can judge whether the rocket will leave the rail under control.
- Compare motors side by side and export your flight card and saved rockets.
- Built-in motor database (thrust curves and certified statistics) plus import of your own .eng / .rse files.
- Switch freely between metric and imperial units.

HOW THE MODEL WORKS (and its limits)
ApogeeField runs a deterministic 1-DOF (vertical, point-mass, with launch-angle cosine) flight integration: thrust-curve integration, variable-mass burn (propellant mass is subtracted as impulse is consumed), quadratic drag, and an ISA standard-atmosphere density model, coasting to apogee at the velocity zero-crossing. Every assumption is shown on the results screen so you can line your inputs up against OpenRocket or your own altimeter data.

It is an engineering estimate for hobby use — a starting point, not a guarantee. The model does not account for wind, airframe stability, roll, or weathercocking, so real flights will differ. Always verify with an altimeter. This is not a safety, airworthiness, or legal document, and it does not replace the NAR / Tripoli safety code or local airspace rules — follow them.

PRIVACY & PRICING
100% offline. No account, no network requests, no analytics, no ads. Your rockets and imported motor files stay on your device. One-time unlock — no subscription. Motor data are numerical facts drawn from publicly submitted thrust-curve files and NAR / Tripoli / CAR certification statistics, stored in our own format with the source and database version shown in the app.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| ApogeeField Unlock | $4.99 | one-time |



## Version history (last 3 releases)

### 1.2 — 2026-06-27

• Refined the App Store listing and search keywords so the right pros can find the app
• Performance and stability improvements

### 1.1 — 2026-06-23

ApogeeField is now an all-in-one field calculator — not just a flight simulator.

NEW · Parachute calculator
• Descent rate from your canopy, or size a canopy for a target rate (4.5–6 m/s / 15–20 ft/s band shown)
• Cd presets per canopy type (flat, dome/elliptical, cross) with the assumption stated — verify with your chute maker

NEW · Black-powder ejection charge estimator
• Ideal-gas estimate with the standard FFFFg constants, adjustable design pressure (15 psi default)
• Always ground test before flight — the reminder stays right next to the number, and prints on the flight card

NEW · Thrust-to-weight everywhere
• TtW badge on every motor in the picker and on the results screen
• Below the 5:1 rule of thumb? You get a clear flag to check rod/rail length and conditions

NEW · PDF flight card (unlock feature)
• One-page card: rocket, motor, predicted apogee, recommended delay, rail-exit check, TtW, parachute and ejection charge — plus date and model assumptions
• Hand it to your RSO at check-in, or file it with your flight log

Still 100% offline, still one-time purchase, still no tracking.
Predictions are estimates, not guarantees — verify with an altimeter.

### 1.0 — 2026-06-12

No release notes.

## More apps by 毅 王

- [Luthier Repair Card](https://appshunter.io/ios/app/luthier-repair-card/id6775381985)
- [GroomSpec: Dog Grooming Guide](https://appshunter.io/ios/app/groomspec-dog-grooming-guide/id6778254427)
- [HeatTreatBench: Knife Steels](https://appshunter.io/ios/app/heattreatbench-knife-steels/id6778304658)
- [PourLog: Concrete Test Log](https://appshunter.io/ios/app/pourlog-concrete-test-log/id6778377971)
- [GroundLoop: Grounding Tests](https://appshunter.io/ios/app/groundloop-grounding-tests/id6779190914)

All apps by 毅 王: https://appshunter.io/developer/6774631380

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-06.*