When I started AFT back in 1994 I had the idea to develop a product for compressible flow in pipe systems. After AFT Fathom 1.0 was released in April 1994 I began research on numerical methods for compressible flow in pipe networks. Books and papers that claimed to offer methods for compressible flow inevitably focused on single pipe applications with adiabatic or isothermal flow - and often with ideal gases. I wanted to develop a real gas software that could model heat transfer and simulate pipe networks. 

Eventually I gave up looking for published methods and set it aside to focus on AFT Fathom 2.0 - which was released in early 1995. I then spent the summer of 1995 focused on developing my own methods for compressible flow. I remember at one point spending six straight weeks reviewing compressible flow textbooks and papers and filling up pads of paper with derivations of potential methodologies. The result in October 1995 was AFT Arrow 1.0, the second visual pipe flow analysis product (after AFT Fathom) and the marketplace's first for compressible flow.

Interest was extremely strong and we started selling licenses immediately. In 1996 I and fellow AFT software developer Jeff Olsen made further tweaks to AFT Arrow 1.0 to improve robustness.

There were a couple things we learned during the period of AFT Arrow 1.0. Some engineers needed a robust tool for doing sonic choking calculations and, while AFT Arrow could certainly do this, it had areas of weakness converging on solutions in certain cases.

We took this experience and developed AFT Arrow 2.0 - which was released in 1999. We were helped in 1999 by a customer who had a pipe system with 20 sonic choking points and had never been able to simulate this with any other tool or their own tools. AFT Arrow 1.0 had struggled simulating their system but the example was timely as it helped give us the insight needed to create AFT Arrow 2.0. Interestingly enough I was also helped by insight gained when writing a technical paper for Chemical Engineering magazine - Gas Flow Calculations: Don't Choke. We found that AFT Arrow 2.0 could reliably and accurately simulate this company's systems and with AFT Arrow 2.0 they had a tool that, according to their own words, revolutionized how they did engineering. We knew we were on to something.

That methodology first developed in AFT Arrow 1.0 and then refined in AFT Arrow 2.0 sixteen years ago is essentially unchanged in today's AFT Arrow 5 and the upcoming AFT Arrow 6 to be released next month. 

As software developers, we get to hear about many of the problems engineering companies have with compressible flow software developed by other companies. I have been contacted and asked to provide technical papers, equations, methods, etc. to such companies so they can show to their customers that the other software is incorrect - with the intent of convincing them to use AFT Arrow. We even have heard directly from some companies how they have sworn to never again deal with some of our competitors.

The problem with other software is something that all engineers already know - that accurately calculating compressible flow is hard. Here is a summary of some of the reasons why: Why Gases Are More Complicated Than Liquids: And How the New AFT Arrow 5 Can Help.

Over the last 20 years AFT Arrow has time and again shown itself to be head and shoulders above other software out there claiming to do compressible flow. I personally am extremely proud of AFT Arrow and the fact that its core methods were developed by AFT. It is AFT Arrow's "secret sauce."