AboutJoe Martin Expertise I can answer questions about Quality Systems (AS9100, AS9103, Boeing D6-82479, etc.) Particular areas of expertise are Statistical Process Control (SPC), sampling inspection, design for Six Sigma, and Six Sigma tools in general.
Experience Quality engineer in aerospace for 20+ years. ASQ Certified Quality Engineer (#8920) since 1982.
Expert: Joe Martin Date: 5/5/2007 Subject: Boeing aircraft models
Question What is the significance of the numeral 7 in most of their aircraft? eg., 727 737 747, etc.
Answer Great question, Tom. Sorry about the delay, but I haven’t had access to my reference sources for a few days and I wanted to consult them before I answered. I still don’t have the definitive story, and haven’t had time to quiz any of my Boeing contacts. Here's what I know:
What was essentially the 707 prototype was given Boeing model number 367-80. The basic model 367 was the prop-driven C/KC-97 transport/tanker which in turn owed much to the B-29 and B-50 bombers. Model 377 was the commercial “Stratocruiser” airliner version of the C-97. The four-hundred series Boeing models included the B-47 and B-52.
Despite the designation, the “dash eighty” was obviously an entirely new design. From what I can tell, this was not an attempt by Boeing to disguise their new project, but simply a convenient model sequence. The production version was marketed as the 707, although I have no sources that go into the rationale. “Seven-oh-seven” was a “catchy” sort of number, and perhaps conveyed a sense of the luck Boeing would need (and got in spades!) in rolling out a company-funding project such as this. With the success of the 707 series, it was a logical choice to keep the “seven” streak going.
A shorter range version of the 707, externally similar but in fact involving considerable design changes, was designated model 720. Indeed, these aircraft were almost universally, if incorrectly, known as 707s. The “missing” model 717 was applied to the military C/KC-135 series. The rest, as the saying goes, is history.
If I come up with anything further, I’ll let you know.
