The names of American manufacturer Boeing's commercial aircraft are known for beginning and ending with the number seven. Starting with the 707 in the 1950s, Boeing has decades of developing popular jetliners with catchy-sounding numerical designations under its belt that generally follow the '7X7' pattern. But what is the reason for this numbering system? Let's take a look and find out.
Theories about Boeing's numbering
There are a handful of interesting theories that have surfaced regarding boeing's numbering system. For example, the University of Houston notes that the numbers 7, 0, and 7 are familiar to engineers the world over as the first three digits in the sine and cosine of 45 degrees. Given the 707's angled wing sweep, some thought that the name could refer to this, but, in reality, the sweep is only 35 degrees.
Another, perhaps slightly more optimistic, idea is that 707 represented the number of passengers it carried. As the Sydney Morning Herald notes, this presumably stems from Airbus having named its A300 after its approximate capacity (which, in reality, went as high as 345). However, this was not the case for the Boeing 707. Even at its exit limit, the largest variant (707-320C) held just 219 passengers.
