gcffm Eventapp vs Rocket Calculator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
gcffm Eventapp
Discover geocaching events in Frankfurt, Germany, and worldwide. Easily add events to your calendar, share details, and navigate to locations. Filter events by area or search to find exactly what you're looking for.
- Event list overview
- Add own events (GPX/web)
- Area categories (Home, Map, Global)
- Add to system calendar
- Copy and share event info
- Open in geocaching/navigation app
- Search and filter events
- Map view
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Don't miss a geocaching event! With this app you will get a list overview of geocaching events around Frankfurt am Main and throughout Germany (as well as bigger events all over the world) Starting with version 2.0 you can also add your own events to the list with .gpx files or via the event website in your browser. Starting with version 3.0 there are three area categories. Home, Map and Global. These help filtering the events you actually want to see. Add the geocaching events easily to your system calendar, copy and share easily important informations of an event, open events in your favourite geocaching or navigation app. Simply long click any event in list view or use the info icon after clicking an event on the map Search and filter your list of events. A map helps you to keep track about events in your area This app was build in cooperation with Geocaching Frankfurt (gcffm).
Rocket Calculator
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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.
Screenshots
Verdict
The clearest difference is in-app purchases: gcffm Eventapp at none against Rocket Calculator's 1. gcffm Eventapp also leads on device support (3 vs 1) and iOS requirement (15.0 vs 17.0). Rocket Calculator's advantage is update cadence (weekly vs monthly). On price and ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Rocket Calculator sells 1 one-off in-app purchase. gcffm Eventapp asks for nothing beyond the download.
gcffm Eventapp ships an update monthly, Rocket Calculator weekly. The most recent releases landed on November 2, 2026 and October 31, 2026 respectively.
| Parameter | gcffm Eventapp | Rocket Calculator |
|---|---|---|
| Price | Free | Free |
| Rating | 4.0 (1 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Monthly | Weekly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | — |
| Devices | iPhone, iPad, iPod — better | iPhone |
| Requires iOS | 15.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 3 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Andre Albach | 毅 王 |
In-app purchases
gcffm Eventapp
No in-app purchases
Rocket Calculator
- ApogeeField Unlock$4.99
Questions
Is gcffm Eventapp free?
Is Rocket Calculator free?
Do gcffm Eventapp or Rocket Calculator have ads?
Which is updated more often, gcffm Eventapp or Rocket Calculator?
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