silly question

[NickM79]

hi

i was wondering if someone could tell me why boeing use the '7' prefix on their aircraft models and why airbus use '3' for theirs.

ive always wondered why but cant find any info on it.

also, another question, is virgins 'a340-331', what does the '331' stand for on the end? obviously its the 300 series, but whats the rest for?

thanks.

[raffele]

The last 2 digits are the customer number. So in this case, 31 is Virgin.

BA's is 36, and so their 747's for example are designated 747-436

As for the 7/3 business, hopefully someone else will come along and answer that for you!

[SLFAussie]

Since I don't have anything better to do (and couldn't find another PPRuNe thread that adequately covers this)

Boeing:

From: Boeing Frontiers Online (http://www.boeing.com/news/frontiers/archive/2004/february/i_history.html)
...700s were set aside for jet transport aircraft

and the Boeing numbering system: Aerospaceweb.org | Ask Us - Boeing Numbering System (http://www.aerospaceweb.org/question/planes/q0048.shtml)

Airbus:

The article Trouble and strife (http://www.airbus.com/en/corporate/history/part_2.html) suggests that the original A300 was named because it was originally intented to carry 300 passengers. Presumably the 3xx designation has stayed ever since.

...a 300-seat A300 was in danger of being too big for the market. With a small team ... he set about designing a scaled-down version of the aircraft which would take up to 250 passengers...

and the Airbus numbering system: Aerospaceweb.org | Ask Us - Airbus Numbering System (http://www.aerospaceweb.org/question/planes/q0276a.shtml)

By the way - Google is your friend

[TightSlot]

I'm sorry I don't have a link (Anybody...? Anybody...? Bueller?) I believe that the original Boeing designator for the 707 was as a result of that being the number of the draughtsmans blueprint - It sounded good, so they used it.

I stand to be corrected...?

[SLFAussie]

From the Boeing website article I posted above (edited for brevity)

...Boeing began studies on converting the propeller-driven model 367 Stratotanker ... into a jet-powered tanker... product development went through several renditions of the model 367, and ... a version numbered 367-80 was selected ... The goal was to put the airplane into production as both an Air Force tanker/transport and a commercial jet transport. Since both of these ... would be jet transports, the model number system called for a number in the 700s... The marketing department decided that "Model 700" did not have a good ring to it ... [s]o they decided to skip ahead to Model 707 because that ... seemed a bit catchier.

Engineering bureaucracy spiced up by marketing!:8

Incidentally, the last two numbers in a Boeing model number work differently to an Airbus model.
Boeing uses a customer number: the '1R' in 747-41R means that the 747-400 was made for Virgin Atlantic.
Airbus uses an engine manufacturer id and version, so an A340-313 is an Airbus A340-300, the '1' means that it uses CFM Interntational (SNECMA/GE) engines, the last '3' means the engine model is 56-5C4 :8:8

[betpump5]

I have been told 2 stories although I can't bothered to Google it at present.

One story is regarding a production certificate 700 - and all models confirm to this "main" number???

The other is (mathematicians please input) the cosine of the tail fin angle is 70.7'??

Either way, both sound a little suspect.