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
VFR Course Calculator
The VFR Course Caclulator calculates true heading, magnetic heading & course, compass heading & course, wind correction angle, cross wind and headwind by entering the true course, wind direction and speed, true air sp...
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
N/A
No ratings yet
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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What's included15 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 VFR Course Calculator: map the core Navigation 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
Implement a more robust saved routes feature with editing capabilities.
Assumption to check: Limited user engagement features like saving routes or historical data
Validate with people who use this workflow before building.
Hypothesis 2
Integrate live weather data for better flight planning.
Assumption to check: No real-time weather updates
Validate with people who use this workflow before building.
Hypothesis 3
Add social sharing options for routes and experiences.
Assumption to check: Lack of community or social features
Validate with people who use this workflow before building.
Hypothesis 4
Redesign UI for a more contemporary look and feel.
Assumption to check: Interface may feel outdated compared to modern apps
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
The VFR Course Caclulator calculates true heading, magnetic heading & course, compass heading & course, wind correction angle, cross wind and headwind by entering the true course, wind direction and speed, true air speed, variation and deviation. Further it is possible to calculate the flight time (TL) for a distance in dependance of groundspeed. Based on these values it calculates fuel demand and weight if you enter the consumption (flow) and fuel density. It does not matter which field you use. The app will automatically convert the entered data in metric, US and UK unit system. The app converts NM (nautical miles), SM (statue miles) an KM (Kilometers) instantly. You can switch in the results for ground speed (GS), cross wind (XW) and head wind (HW) between knots (kt) or kilometres per hour (kph) True course, true heading, wind direction and wind speed is visualised with a vector (TC), aircraft symbol (TH) and wind barb (WD & WS). If you want to calculate only the flight time and/or fuel and know your groundspeed, just put your groundspeed into field "true air speed" and enter flight distance "distance leg", fuel demand (burn per hour) and fuel density. Leave the other fields empty. This app is useful to pilots and aircraft apprentices for planning your VFR flight fast and easily. App is running natively on iPhone and iPad. The app is completely written in LiveCode.
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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.
SUGGESTED BUILD STACK
React Native
Expo
react-navigation
redux
react-native-paper
expo-location
BUILD KIT DIFFICULTY
Intermediate
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.
