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.
App Overview
Gear Speed - Brushless RC Speed Calculator
Gear Speed is the best gearing tool for your brushless RC car
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 3.8
120 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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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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Combine features and design from your favorite apps.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
What's included17 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.
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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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Gear Speed - Brushless RC Speed Calculator: map the core Utilities workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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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
Include additional calculation options and features like presets for different RC vehicles.
Assumption to check: Limited features compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Streamline settings with clearer options and a tutorial.
Assumption to check: Difficult to navigate settings
Validate with people who use this workflow before building.
Hypothesis 3
Optimize app performance for older iOS versions.
Assumption to check: Occasional crashes on older devices
Validate with people who use this workflow before building.
Hypothesis 4
Add functionality to export results to CSV or email.
Assumption to check: No export options for results
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
Gear Speed is the best gearing tool for your brushless RC car. Forget the slow web calculators with limited features. Gear Speed was designed for you and your speed quest. Gear Speed calculates your maximum speed. It stores your setups, allows you to include notes for your runs and your setup changes. You can also email this information for permanent record keeping. Calculates: Speed (MPH/KPH), RPM, Final Drive Ratio, Rollout (now in Inches and MM). Given: Pinion Size, Spur Size, Transmission Ratio, Tire Diameter (inches/mm), Motor KV, LiPo cell count and cell voltage. Gear Speed now handles from 1S to 12S LiPo batteries. Please contact us at ussapps.com to let us know how to make this app even better. Happy racing! * Note: The above screens are sample setups, you will need to enter your own car's information.
Written user reviews are not shown here. Check current App Store reviews >
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.
SUGGESTED BUILD STACK
React Native
Expo
React Navigation
react-native-clipboard
react-native-share
Zustand
BUILD KIT DIFFICULTY
Starter
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.
