# OPie Isentropic Calculator — Engineering Gas Flow

> Compressible aerodynamic flow calculator for shock, Fanno, and Rayleigh conditions. (iPhone/iPad app by Andrew Swenson.)

- Source: https://appshunter.io/ios/app/opie-isentropic-calculator/id1558926421 (this page in markdown: same URL + `.md`)
- Developer: [Andrew Swenson](https://appshunter.io/developer/1558926423)
- Category: Utilities, Education
- Price: Free with in-app purchases
- Rating: 4.50/5 from 14 App Store ratings
- Age rating: 4+
- Requires: iOS 14.2 · 8 MB
- Languages: American English
- Released: 2021-03-18
- Data updated: 2026-07-04
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/opie-isentropic-calculator/id1558926421/reviews.md

## What is OPie Isentropic Calculator?

OPie Isentropic Calculator is a compressible aerodynamic flow calculator that also calculates the 90 degree (Normal) shock, Oblique Shock, Fanno Flow, and Rayleigh conditions.

## Key features

- Compressible aerodynamic flow calculations
- Normal shock calculations
- Oblique shock calculations
- Fanno flow calculations
- Rayleigh conditions calculations

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Remove Ads | $2.99 | one-time |



## Frequently asked questions about OPie Isentropic Calculator

### What is OPie Isentropic Calculator used for?

OPie Isentropic Calculator is used for performing various compressible aerodynamic flow calculations, including normal shock, oblique shock, Fanno flow, and Rayleigh conditions.

### What devices is OPie Isentropic Calculator available on?

OPie Isentropic Calculator is available on iPhone, iPad, and iPod devices.

### What is the age rating for OPie Isentropic Calculator?

OPie Isentropic Calculator has an age rating of 4+, making it suitable for a wide range of users.

### How often is OPie Isentropic Calculator updated?

The latest version, 5.1, was released on November 16, 2021. The app was initially released on March 18, 2021.

### What is the user rating for OPie Isentropic Calculator?

OPie Isentropic Calculator has a strong rating of 4.5 stars based on 14 user ratings.

### Is OPie Isentropic Calculator free to use?

Yes, OPie Isentropic Calculator is available for free.

### Does OPie Isentropic Calculator have ads?

The provided data does not specify if OPie Isentropic Calculator contains advertisements.

### What specific engineering fields does OPie Isentropic Calculator support?

This calculator specifically supports compressible aerodynamic flow analysis, including shock phenomena and flow conditions like Fanno and Rayleigh.

## Version history (last 5 releases)

### 5.1 — 2021-11-16

-Remove ads in app purchase now takes place without restarting app.
-improved layout across a multitude of screen sizes

### 5.0 — 2021-10-23

Fixed: 
  -Rayleigh Page temperature ratio buttons.
  -charts with sliders for smoother operation
removed:  tabBar from all plot screens (navigate back with the back button)
New Features:
  -added buttons to many of the plot pages to select and deselect specific data
  -added info pages to both Fanno and Rayleigh
  -added multiple Fanno and Rayleigh plots
  -added the ability to hide/show the tab bar by swiping up or down
  -added button border highlights to indicate whether a supersonic or subsonic solution

### 4.22 — 2021-09-21

added: Tab Bar images

### 4.21 — 2021-09-11

Added Feature:  Ability to remove advertising (a customer specifically requested this feature)
Fix: App is not supposed to display in landscape mode on an iPhone.  This is now fixed.

### 4.2 — 2021-06-24

Fanno and Rayleigh Pages:  Fixed truncated button text on the smaller iPhone displays. 
Other:  Fixed a screen rotation issues on some of the plot and information pages.

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## More apps by Andrew Swenson

- [OPie RPN Calculator](https://appshunter.io/ios/app/opie-rpn-calculator/id1559116337)
- [OPie RetireFIRE](https://appshunter.io/ios/app/opie-retirefire/id1562734440)
- [OPie Unit Converter](https://appshunter.io/ios/app/opie-unit-converter/id1570481314)
- [OPie Tip Calc](https://appshunter.io/ios/app/opie-tip-calc/id1570900875)
- [OPie Mohr's Circle](https://appshunter.io/ios/app/opie-mohrs-circle/id1581023550)

All apps by Andrew Swenson: https://appshunter.io/developer/1558926423

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-04.*