# Apexline — Model rocket flight computer > Model rocket flight computer (iPhone/iPad app by Robert Corbin.) - Source: https://appshunter.io/ios/app/apexline/id6777868815 (this page in markdown: same URL + `.md`) - Developer: [Robert Corbin](https://appshunter.io/developer/1890247992) - Category: Utilities, Education - Price: $3.99 - Age rating: 4+ - Requires: iOS 17.0 · 49 MB - Languages: English - Released: 2026-06-13 - Data updated: 2026-08-09 - User reviews in markdown: https://appshunter.io/ios/app/apexline/id6777868815/reviews.md ## What is Apexline? Apexline is the offline flight computer for model rocketry. Whether you fly Estes kits with the kids, chase a target altitude for a contest, or build your own designs, Apexline answers the questions that matter on the launch field — how high will it go, which ejection delay should I use, will it fly straight, what chute do I need, and is this launch-day setup inside a safer planning range — all without an account, ads, or an internet connection. HOW HIGH WILL IT GO? Enter your rocket's mass, diameter, and drag, pick a motor, and Apexline simulates the whole flight — boost, coast, and the climb to apogee. It reports your predicted altitude, time to apogee, maximum speed and acceleration, burnout altitude, and the speed coming off the launch rod, plus a clean altitude-vs-time graph. Launch-site altitude and air temperature are factored in, because thinner air flies higher. WHICH DELAY? (THE MOST COMMON MISTAKE) Deploy too early and the parachute shreds; too late and the rocket nose-dives. Apexline calculates the optimum ejection delay — the exact coast time to apogee — then tells you which of your motor's available delays is closest. For a typical Estes Alpha on a C6, it recommends the C6-5, just like the catalog. WILL IT FLY STRAIGHT? Apexline finds your rocket's center of pressure with the Barrowman equations (the same method desktop simulators use) from your nose and fin geometry. Enter the balance point and it shows the static margin in calibers with a clear verdict — unstable, marginal, stable, or overstable — and a live diagram of CP and CG so you can see the margin before you fly. PICK THE RIGHT MOTOR Browse a built-in catalog of common Estes, Quest, AeroTech and Klima motors, organized by impulse class, with total impulse, thrust, burn time, available delays, and masses. Not sure what "C6-5" means? The decoder spells out the class, the average thrust, and the delay from any motor code you type. LAND IT SAFELY Size a parachute or streamer for a gentle landing. Apexline computes descent rate and landing energy, recommends a canopy size for your target descent speed, and estimates downwind drift so you don't lose your rocket on a windy day. RUN A LAUNCH READINESS CARD The Launch Readiness Card combines altitude simulation, Barrowman stability, descent and drift estimates, field size, wind, rod-exit speed, and ejection delay into a single go/caution/hold checklist. It is designed for field planning, not hardware control. LEARN THE HOBBY Twelve illustrated guides cover how a rocket flies, reading motor codes, the impulse ladder, choosing a delay, stability, altitude, recovery, your first launch, hitting a target altitude, a plain-language summary of the Model Rocket Safety Code, comparing motors side by side, and reading your flight statistics — plus a 40-term glossary, quick-reference tables, and a bundled offline field-card deck. BUILT THE WAY APPS SHOULD BE • Completely offline — works on any launch field, no signal needed • No account, no sign-in, no ads, no tracking, no in-app purchases • Save your rockets and they flow across every calculator • Metric or imperial results • Clean, fast, and built for repeat field use Apexline is an estimation and reference tool for a great hobby. Motor specifications are typical published values for planning — always confirm against the certified data on the motor — and every flight should follow the official Model Rocket Safety Code, the motor instructions, and your local laws. ## Version history (last 5 releases) ### 2.2 — 2026-07-02 New Two-Stage & Cluster Planner: simulate a booster + sustainer flight or a multi-motor cluster - staging altitude and speed, total apogee, and the right sustainer delay to fly. New Flight Duration Planner predicts your total flight time from liftoff to landing and sizes the chute to hit a contest duration window. Plus, share any rocket design as a file and import designs from teammates - perfect for clubs and student teams, no account needed. ### 2.0.1 — 2026-06-23 This update sharpens the interface: the iPad layout now uses a centered, comfortable reading width instead of stretching edge to edge, so every screen reads as a clean column. iPhone is unchanged; still fully on-device. ### 1.2 — 2026-06-15 Version 1.2 • Motor Compare — the most-requested workflow improvement. Tap the arrows icon in the Motors tab to open the new Motor Compare screen. Select up to 8 motors from the full catalog and Apexline runs the complete flight simulation for each one against your current rocket in one pass. Results are ranked in a table with apogee, thrust-to-weight, rod-exit verdict, optimum delay, and the best-matching available delay for each motor. Sort by any column. An optional bar chart shows the apogee spread at a glance. No more switching motors one at a time on the Altitude tab. • Flight Stats — tap the chart icon in the Flight Log toolbar to see a summary of your prediction accuracy across all flights with altimeter readings: mean error, mean absolute error percentage, a verdict on calibration quality, and a flight-by-flight error trend chart. Colour-coded dots show which flights were within 10 %, which were off, and whether accuracy is improving over time. • Two new Learn guides — "Comparing motors side by side" (how to get the most from Motor Compare) and "Reading your flight statistics" (how to interpret the error trend and use Cd calibration to close the gap). ### 1.1 — 2026-06-14 Version 1.1 • Flight Log — record your actual flights with the motor used, measured apogee, notes, and launch site. Compare your altimeter reading against the simulation's prediction and see a running error percentage so you know how well your Cd estimate tracks reality. Export all entries as a CSV file. • Cd Calibration — enter a measured apogee and Apexline back-calculates the exact drag coefficient that would have produced it, then lets you apply it to your rocket profile with one tap. • Field & Safety Calculator — enter your motor class and field size to check the NAR minimum field requirement. Separate drift calculator shows how much field you need to contain the rocket at your deployment altitude, descent rate, and wind speed. Wind-limit checker shows the maximum safe wind for your rod-exit speed. • Expanded motor catalog — added Apogee Components motors (A7, B6, C10, D3, E6) and additional AeroTech composite motors (F39, G25, G40, H45, H73, I161, J180). • Log Flight shortcut — after any altitude simulation, a "Log this flight" button pre-fills the motor and predicted apogee so recording a flight takes seconds. ### 1.0 — 2026-06-13 No release notes. ## More apps by Robert Corbin - [Daily Word Journey](https://appshunter.io/ios/app/daily-word-journey/id6761548266) - [Hush Secret Text](https://appshunter.io/ios/app/hush-secret-text/id6761658175) - [Renew Guard](https://appshunter.io/ios/app/renew-guard/id6761755447) - [Receipt to PDF](https://appshunter.io/ios/app/receipt-to-pdf/id6761782025) - [Route Your Pay](https://appshunter.io/ios/app/route-your-pay/id6761783719) - [Tip Arbiter](https://appshunter.io/ios/app/tip-arbiter/id6761786879) All apps by Robert Corbin: https://appshunter.io/developer/1890247992 --- *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 2026-08-09.*