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Why Were 707 Variants Given "20 Series" Numbers?  
User currently offlinehomsar From United States of America, joined Jan 2010, 1183 posts, RR: 0
Posted (4 years 3 weeks 5 days 6 hours ago) and read 3448 times:

Over the years, I've read a bunch of stuff (in books and online) about Boeing's history and how the 707 designation came to be. However, none of them (that I can remember) ever said anything about why the 707s were called 707-120, -320, etc.

This practice wasn't used after the 707 model (the first 747 wasn't the 747-120). What was their reason for doing so the first time around?

A secondary question to that is, why did Boeing give themselves the internal "customer code" of 20 (as opposed to 00, 01, or 64)?


I was raised by a cup of coffee.
15 replies: All unread, jump to last
 
User currently offlinecrownvic From United States of America, joined Oct 2004, 1912 posts, RR: 5
Reply 1, posted (4 years 3 weeks 5 days 2 hours ago) and read 3289 times:

Seems that there are lots of mysteries in the Boeing numbering system. You could go one step further. What was the reason for the 7-0-7 name in the first place? Was it because Mr. Boeing liked the "7" as being a lucky number? The lineage of the models 247, 307 & 377 seems obvious that their passenger aircraft must have a "7" in it. I have never read where any of the Boeing numbers meant anything. Unlike their counterparts, most of them had meaning. Douglas' numbering system of "DC" for Douglas Commercial followed a sequential order. Made sense. Even Convair, with the CV-880 I think meant 880 feet per second for it's cruising speed.

The true answers to the Boeing numbering system may have been lost many years ago, but as I mentioned above, there does not appear to be any significant reason for the "20" in their series either. If I had to guess, like the "7", Mr. Boeing may have had a particular liking to this number vs. it being something technical.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 2, posted (4 years 3 weeks 5 days 2 hours ago) and read 3258 times:

Quoting crownvic (Reply 1):
The lineage of the models 247, 307 & 377 seems obvious that their passenger aircraft must have a "7" in it.

That's just a coincidence...back that early in the Boeing numbering system, each design just went in numerical order. Several of those with 7's happened to be passenger jets, but not all (e.g. the Model 80). Many many designs aren't produced, which is why the numbering of produced aircraft has such big gaps.

Quoting crownvic (Reply 1):
I have never read where any of the Boeing numbers meant anything.

For a long time, it was just the order in which they were designed. So far, they've continued to increase the number with each design, but with jumps.

Quoting crownvic (Reply 1):
Douglas' numbering system of "DC" for Douglas Commercial followed a sequential order.

So does Boeing in the jet age...707 through 787, jumping by 10's. 717 was used once for what is now the KC-135 and then repeated for the MD-90 successor.

Quoting crownvic (Reply 1):
If I had to guess, like the "7", Mr. Boeing may have had a particular liking to this number vs. it being something technical.

Mr. Boeing didn't have that much to do with running the company by the time the 707 came around...he stopped being much in the day-to-day business after the United/P&W/Boeing breakup.

Tom.


User currently offlineFlyNWA727 From United States of America, joined Jan 2010, 305 posts, RR: 0
Reply 3, posted (4 years 3 weeks 5 days 2 hours ago) and read 3258 times:

Quoting crownvic (Reply 1):
Seems that there are lots of mysteries in the Boeing numbering system. You could go one step further. What was the reason for the 7-0-7 name in the first place? Was it because Mr. Boeing liked the "7" as being a lucky number? The lineage of the models 247, 307 & 377 seems obvious that their passenger aircraft must have a "7" in it. I have never read where any of the Boeing numbers meant anything. Unlike their counterparts, most of them had meaning. Douglas' numbering system of "DC" for Douglas Commercial followed a sequential order. Made sense. Even Convair, with the CV-880 I think meant 880 feet per second for it's cruising speed.

The true answers to the Boeing numbering system may have been lost many years ago, but as I mentioned above, there does not appear to be any significant reason for the "20" in their series either. If I had to guess, like the "7", Mr. Boeing may have had a particular liking to this number vs. it being something technical.

I would suggest to anyone to do a little bit of research to find out some useful information. That's the obvious reasoning for having access to the worldwide web... you can find out almost anything lol. There was a thread on A.net recently that discussed ad nauseam, that reasoning behind the boeing 7x7 line of products. I can not find that thread, but if you visit this link http://www.boeing.com/news/frontiers...chive/2004/february/i_history.html found on Boeing's website, they discuss how the 707 name (and future products) came to be.

In response to the thread starter, I have no idea why the 707-120 was used. I do know that the shrunken Boeing 720 was originally called the 707-020 and then Boeing changed it to the Boeing 720 because of an issue with launch customer, United Airlines.

[Edited 2010-08-21 22:21:49]


First flight aboard a Northwest B727-251ADV out of BWI Thurgood Marshall Airport, my hometown airport.
User currently offlinecrownvic From United States of America, joined Oct 2004, 1912 posts, RR: 5
Reply 4, posted (4 years 3 weeks 4 days 4 hours ago) and read 2875 times:

FlyNWA727...This is a discussion forum and not necessarily a confirmed "Information Center"...If you restrict responses to bona-fide answers, then you may as well just shut this forum and 75% of the Internet down! If I nit-picked every response on this web site, it would be a full time job. Your comment was inappropriate...

User currently offlinemestrugo From Chile, joined Apr 2007, 237 posts, RR: 0
Reply 5, posted (4 years 3 weeks 4 days 3 hours ago) and read 2789 times:

Quoting homsar (Thread starter):
Over the years, I've read a bunch of stuff (in books and online) about Boeing's history and how the 707 designation came to be. However, none of them (that I can remember) ever said anything about why the 707s were called 707-120, -320, etc.

This practice wasn't used after the 707 model (the first 747 wasn't the 747-120). What was their reason for doing so the first time around?

A secondary question to that is, why did Boeing give themselves the internal "customer code" of 20 (as opposed to 00, 01, or 64)?

I'm not very sure, but I think it MAY be related with an internal indication about the configuration of the plane's wings. While I was reading about parasite fighters, I learned that the idea was revived in the late 70s-early 80s by Boeing (planning to use up to 10 microfighters using a 747s as motherships!), and found that different wing configurations were tested:

Model 985-1 air based micro fighter delta configuration
Model 985-10 air based micro fighter vitac configuration
Model 985-20 air based micro fighter arrow configuration
Model 985-30 air based micro fighter canard configuration
Model 985-40 air based micro fighter VSW configuration
Model 985-121 air based micro fighter advanced technology (1980s), arrow configuration

If this theory was true, the '20' series would indicate the swept back wing configuration of the 707. Of course, it's just a theory.


User currently offlineFlyCaledonian From United Kingdom, joined Dec 2003, 2089 posts, RR: 3
Reply 6, posted (4 years 3 weeks 3 days 22 hours ago) and read 2578 times:

Having given themselves the customer number of 20, Being then started from there upwards when allocating them to airlines (21 for Pan Am, 22 for United, etc). at 99 (Caledonian) they then dropped to 01 (Piedmont) and after 19 (TEAL) moved on to the alpha-numeric codes.


Let's Go British Caledonian!
User currently offlinemilesrich From United States of America, joined Jul 2003, 1997 posts, RR: 6
Reply 7, posted (4 years 3 weeks 3 days 13 hours ago) and read 2318 times:

Lockheed had the strangest numbering system.

The first Electra was the L-10, followed by the smaller L-12, then the L-14, the the L-18 Lodestar, followed by the L-049 Constellation, the L-649 Constellation, the L-749 Constellation, the L-1049 Constellation, then the L-1049C,D,E,G,H, and finally the L-1649 Constellation, followed by the L-188 Electra, and L-1011 Tristar. Tell me the reasoning there.

I think Boeing used 707-120 because at the time, when they started assigning airlines numbers for the models built for them, they didn't start with -01. Piedmont got that number later. They started with -21 for Pan Am, the first customer, reserved -22 for United, -23 for American etc. When the numbers were assigned, the 727 and 737 were not even considered. Hence, the generic term was 120 domestic version with JT-3's, 220 domestic version with JT-4's, 320 international version with JT-4's, and 420 international version with RR Conways, and 020 for what became the 720.


User currently offlinekanban From United States of America, joined Jan 2008, 3547 posts, RR: 26
Reply 8, posted (4 years 3 weeks 3 days 11 hours ago) and read 2204 times:
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Quoting tdscanuck (Reply 2):
Mr. Boeing didn't have that much to do with running the company by the time the 707 came around...he stopped being much in the day-to-day business after the United/P&W/Boeing breakup.


Mr Boeing retired in 1934 after the forced break up of the company and only returned as a consultant during WWII..

Bill Allen probably had more to do with the numbering system...


User currently offlineredflyer From United States of America, joined Feb 2005, 4327 posts, RR: 28
Reply 9, posted (4 years 3 weeks 3 days 9 hours ago) and read 2090 times:

Quoting tdscanuck (Reply 2):
717 was used once for what is now the KC-135 and then repeated for the MD-90 successor.

Not trying to split hairs or detract from your otherwise always informative answers and commentary, but the 717 was the successor nomenclature to the MD-95, not MD-90.  



My other home is a Piper Cherokee 180C
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 10, posted (4 years 3 weeks 3 days 6 hours ago) and read 1981 times:

Quoting redflyer (Reply 9):
717 was the successor nomenclature to the MD-95, not MD-90

Nuts! I'd written MD-95 then corrected myself, thinking I was getting it wrong. Thank you for setting me straight.

Tom.


User currently offlineViscount724 From Switzerland, joined Oct 2006, 25300 posts, RR: 22
Reply 11, posted (4 years 3 weeks 3 days 5 hours ago) and read 1954 times:

Quoting milesrich (Reply 7):
I think Boeing used 707-120 because at the time, when they started assigning airlines numbers for the models built for them, they didn't start with -01

The question is why? I've never seen an explanation for that. Books on 707 history always explain the origin of the 707 (and 720) desginations, but never explain why Boeing chose the generic model numbers -120/-220/-320/-420 for the 707 (with -20 as their own code) rather than -100/-200/-300/-400 and starting the customer codes with "01" rather than "21". There must be an answer to that somewhere in Boeing archives.


User currently offlineebj1248650 From United States of America, joined Jun 2005, 1932 posts, RR: 1
Reply 12, posted (4 years 3 weeks 3 days 3 hours ago) and read 1888 times:

Quoting redflyer (Reply 9):
Not trying to split hairs or detract from your otherwise always informative answers and commentary, but the 717 was the successor nomenclature to the MD-95, not MD-90.

And the original Model 717 designation applied to the C-135 series of airplanes.



Dare to dream; dream big!
User currently offlineKELPkid From United States of America, joined Nov 2005, 6381 posts, RR: 3
Reply 13, posted (4 years 3 weeks 3 days 2 hours ago) and read 1879 times:

Folks:

Remember that the Dash Eighty (the prototype of all Boeing 4-engined jetliners) was officially the Boeing model 367-80.

I remember watching a videotape series my dad owned, called "Reach for the Skies", jointly produced by CBS and the BBC, which had interviews with key Boeing personnel (produced in the mid to late 1980's), stating that Bill Allen publicly annnounced the project (four engined civil jetliner) as the "Seven Oh Seven" to throw a curveball to his competitors (before the dash 80 was revealed to the public). Before that, you could kind of guess what was going on with a project at Boeing based on Boeing model numbers...

Which would seem to confirm:

Quoting mestrugo (Reply 5):
I'm not very sure, but I think it MAY be related with an internal indication about the configuration of the plane's wings. While I was reading about parasite fighters, I learned that the idea was revived in the late 70s-early 80s by Boeing (planning to use up to 10 microfighters using a 747s as motherships!), and found that different wing configurations were tested:

Model 985-1 air based micro fighter delta configuration
Model 985-10 air based micro fighter vitac configuration
Model 985-20 air based micro fighter arrow configuration
Model 985-30 air based micro fighter canard configuration
Model 985-40 air based micro fighter VSW configuration
Model 985-121 air based micro fighter advanced technology (1980s), arrow configuration

If this theory was true, the '20' series would indicate the swept back wing configuration of the 707. Of course, it's just a theory.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlinemilesrich From United States of America, joined Jul 2003, 1997 posts, RR: 6
Reply 14, posted (4 years 3 weeks 2 days 18 hours ago) and read 1752 times:

Quoting KELPkid (Reply 13):
Remember that the Dash Eighty (the prototype of all Boeing 4-engined jetliners) was officially the Boeing model 367-80.

I remember watching a videotape series my dad owned, called "Reach for the Skies", jointly produced by CBS and the BBC, which had interviews with key Boeing personnel (produced in the mid to late 1980's), stating that Bill Allen publicly annnounced the project (four engined civil jetliner) as the "Seven Oh Seven" to throw a curveball to his competitors (before the dash 80 was revealed to the public). Before that, you could kind of guess what was going on with a project at Boeing based on Boeing model numbers...

And also remember that the Boeing 367 was the cargo/tanker/military version of the Boeing 377 Stratocruiser. Although the 367-80 airframe had no real relationship to the 367, the designation 367-80 was also used, I believe, for corporate security reasons while the airplane was being developed. Hence, after it was unveiled, it was always referred to as the Dash 80, however, the original model 717 is more closely related to the Dash 80 than the commercial version, but as most of you know, the commercial version fuselage was widened when C.R. Smith of American supposedly told Bill Allen he would order the DC-8 which could seat six across in coach which the original 707 could not do. Pan Am had already split their order and looked at their 707's as possible interim aircraft before this change was made to the 707. Had Boeing not made the change, the company might not even be arround today, because at the time, Douglas dominated the commercial transport business, and Boeing had not produced a commercially successful airliner, due to timing, and marketing mistakes. In fact, the 707 might have been as big a bust as the CV-880/990 program at General Dynamics. But Allen took the gamble, had the fuselage redesigned to accomodate six across, and the company today is still building aircraft based on the widened design.


User currently offlineViscount724 From Switzerland, joined Oct 2006, 25300 posts, RR: 22
Reply 15, posted (4 years 3 weeks 2 days 5 hours ago) and read 1550 times:

Quoting milesrich (Reply 14):
Although the 367-80 airframe had no real relationship to the 367, the designation 367-80 was also used,

The Dash 80 has one thing in common with the 367 and 377 -- the same 132 inch fuselage width.


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