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
Fluid Mechanics Pack
Fluid Mechanics Pack – The Ultimate Engineering Toolkit
$3.99 · In-app purchases
PRICE
$3.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
12 ratings · Top 5%
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 included16 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
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 Fluid Mechanics Pack: map the core Reference 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
Expand content with more examples and interactive problems.
Assumption to check: Limited formulas and explanations
Validate with people who use this workflow before building.
Hypothesis 2
Add community features like discussions or Q&A.
Assumption to check: Lack of user engagement features
Validate with people who use this workflow before building.
Hypothesis 3
Implement guided tours or tutorials for navigating the app.
Assumption to check: Difficult navigation for new users
Validate with people who use this workflow before building.
Hypothesis 4
Enable offline access for previously viewed formulas and topics.
Assumption to check: No offline access
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
Fluid Mechanics Pack – The Ultimate Engineering Toolkit This App is a powerful tool featuring 97 calculators and 28 converters designed for Fluid Mechanics, Civil Engineering, and Structural Engineering. Whether you’re a student, engineer, or researcher, this app helps you calculate essential parameters with ease. Supports Both Unit Systems • USCS (Imperial Units) • SI (Metric Units) Key Calculators & Equations Fluid Mechanics & Engineering Calculations • Pressure & Forces: Absolute Pressure, Brake Horsepower, Buoyant Force, External Hydrostatic Pressure • Flow & Velocity: Flow Rate, Bernoulli’s Theorem for Head Loss, Manning Flow Velocity, Hydraulic Radius • Viscosity & Diffusion: Kinematic Viscosity, Liquid Phase Diffusion Coefficient • Efficiency & Power: Pump Efficiency, Water Horsepower • Losses & Head Calculations: Minor Losses, Net Positive Suction Head (NPSH), Cavitation • Specific Properties: Specific Gravity, Specific Gas Constant, Specific Volume Flow Meters & Weirs • Acoustic Flow Meter, Venturi Meter, Orifice Flow Rate • Rectangular Weir (Francis Equation), V-Notch Weir, Parshall Flume Flow Rate • Hazen-Williams Fluid Flow Rate & Velocity Pipe & Structural Calculations • Pressure Ratings for Aluminum, Plastic, Steel, and Ductile Iron Pipes • Soil Load Per Linear Length of Pipe, Unrestrained Pipe Length Change • Pipe Vacuum Pressure Load, Water Buoyancy Factor, Restrained Anchored Pipe Stress Important Fluid Dynamics Numbers • Reynolds Number, Mach Number, Weber Number, Froude Number • Prandtl Number, Schmidt Number, Sherwood Number, Knudsen Number • Cauchy Number, Euler Number, Peclet Number, Lewis Number Darcy’s Law & Water Hammer • Head Loss, Flow Rate, Hydraulic Gradient, Void Ratio, Porosity • Maximum Surge Pressure for Fluids & Water, Pressure Increase 28 Powerful Unit Converters Convert between different units for: • Acceleration, Angle, Area, Density, Energy, Force • Flow Rate (Mass & Volume), Fluid, Frequency, Length, Mass • Moment of Force, Moment of Inertia, Pressure, Specific Heat Capacity • Specific Volume, Temperature, Thermal Conductivity, Thermal Expansion • Time, Torque, Velocity, Viscosity (Dynamic & Kinematic), Volume Your Complete Fluid Mechanics & Engineering Guide • Accurate and easy-to-use calculators • Supports both Imperial and Metric units • Essential for Civil, Structural, and Mechanical Engineers
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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
Supabase
Zustand
react-navigation
react-native-gesture-handler
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.
