App Overview

GPS Rally Computer icon

GPS Rally Computer

MSYapps · Sports

GPS Rally Computer is a Universal app designed to simplify computations necessary to navigate a traditional time-speed-distance (TSD) automobile rally

$24.99 · In-app purchases

PRICE
$24.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
3.8
5 ratings · Top 50%

Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.

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What's included16 files

A product spec, phased build plan, differentiation notes, and screen references.

  • START_HERE
  • AGENTS
  • EVIDENCE
  • SPEC
  • BUILD_PLAN
  • DIFFERENTIATION
  • skills/
  • screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.

Feature spec

Goal: Send a clear invoice after finishing a job.

  • Add a client, line items, a due date, and payment instructions.
  • Preview the total before exporting a PDF.
  • Keep an editable draft if export fails.

Screen plan

Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.

States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.

Differentiate and validate

Hypothesis: Contractors need faster repeat invoices more than more templates.

First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.

The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.

Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.

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Opportunities

AI-GENERATED OPPORTUNITY HYPOTHESES

These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.

Hypothesis 1

Add more advanced navigation tools and user customization options.

Assumption to check: Limited features compared to competitors

Validate with people who use this workflow before building.

Hypothesis 2

Implement a more guided onboarding process.

Assumption to check: User interface can be confusing

Validate with people who use this workflow before building.

Hypothesis 3

Use better algorithms for tracking and error correction.

Assumption to check: Inaccurate GPS tracking issues

Validate with people who use this workflow before building.

Hypothesis 4

Introduce a freemium model with essential features available for free.

Assumption to check: High price point for basic features

Validate with people who use this workflow before building.

App evidence

Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.

App Store description

GPS Rally Computer is a Universal app designed to simplify computations necessary to navigate a traditional time-speed-distance (TSD) automobile rally. The design and implementation is based on specifications outlined by Clarence Westburg and Rich Bireta, commonly known as the Simple Rally Computer or its acronym SRC. The User's Manual is available on the app detail page linked at http://www.msyapps.com. A TSD rally is comprised of stages set along a route defined by written instructions. The first stage is the Odometer Check stage that allows you to calibrate your car’s odometer with that of the Rally Master’s odometer. In later stages you will follow a course at a particular average speed that will change from time to time at places that are generally unknown in advance. In order to drive the course at the prescribed speeds. Odometer measurement is obtained from Apple’s GPS receiver or third-party devices via Bluetooth. The GPS Rally Computer allows you to do all this and much, much more. For additional documentation, download the User’s Guide. Features of the GPS Rally Computer: - Clock time in either minutes and seconds to tenths of a second or decimal minutes to thousandths of a minute - The clock is a 24-hour clock to simplify computations - Distance measurements in either miles or kilometers to either two- or three-digit precision - One button click to reset default conditions for starting a rally - The internal computer clock can be adjusted to match the official rally clock - The distance between the GPS receiver and the position on the car where the rally measurements are taken (the front wheels, for example) can be added for improved distance precision - A "sprocket" button in the top menu bar allows access to the app settings from within the running application including settings for display of certain items - Calibrate the car's odometer to the official rally odometer on the odometer check stage via a popup - Change average speed (CAST) on a custom popup keypad - Preselect the next CAST to simplify the process of changing speed on each stage and setting CAST to zero for transit zones - As time passes and as the car's odometer is incremented, the actual speed over the course is compared with the expected speed. The difference in seconds or hundredths of a minute is displayed along with an indication to either “Early” or “Late” to stay on pace. - Time errors may be displayed in either of two modes selectable in the app Settings - Pause or Gain time or take a Time Allowance on any leg or within a transit zone - Handle off-course corrections to time and distance with a Reverse button - Record "splits" of time and error at any time with a Split button - Record "control" and reset time error and distance to zero and increment next starting time 5 minutes later (distance and time are modifiable) with a Control button. - Set next starting time for the Next CAST and have the time tick down on the master clock and autostart CAST, or override with a manual button click - Optionally, use a Dual GPS receiver via Bluetooth to supplement or substitute for the Apple internal GPS - Connects to TSD Remote app that serves as a driver's heads-up display connected via local network. Note: Use of the GPS Rally Computer during any particular rally will be subject to the rules and instructions governing the rally and may also define your category or class among race participants. Some rallies may, in fact, prohibit use of this app. This app has been tested with Bluetooth connectivity to a Dual XGPS150A Universal GPS Receiver. Disclaimer: Continued use of GPS running in the background can dramatically decrease battery life.

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Screenshots

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Build scope

Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.

Define the first version

Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.

Set boundaries

Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.

Check the hard parts

Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.

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BUILD KIT DIFFICULTY
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From the Build Kit assessment.

A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.