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Hi!

I always had the feeling that the 707-400 was taller than the other 707 versions, and a few weeks ago I confirmed that, indeed the 707-400 is the tallest 707, and that comes to a question, why the 400 series had a different tail than the other versions?
I wait your feedback.
Regards

707-400 is there such a plane?

Quoting SOBHI51 (Reply 1): 707-400 is there such a plane?

Er, ya!


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Photo © John M. Wheatley

For the young ones among you, the 707-400 was the Rolls Royce of the 707's, ie it was powered by Rolls Royce Conway engines and operated by BOAC, Varig and Air India and maybe others but I can't remember just now

You learn something new everyday. Thanks

Hi CV990!

Quoting CV990 (Thread starter): 707-400 was taller than the other 707 versions

The 420 was just as tall as the 320b and 320c at 42ft 5in, the 320 was 41ft 8in

Quoting PenPusher (Reply 3): For the young ones among you, the 707-400 was the Rolls Royce of the 707's, ie it was powered by Rolls Royce Conway engines and operated by BOAC, Varig and Air India and maybe others but I can't remember just now

The 420 was operated by BOAC (19), Lufthansa (5), ElAl (3), Air India (6) and VARIG (3)

Hope this is some help for you
Scooter

Quoting CV990 (Thread starter): why the 400 series had a different tail than the other versions?

Because it flew at higher altitudes than the 707-100/200, and incurred higher levels of turbulance, with the conway engines having a higher rate of air bypassing the engine nacelle and with the CAA requiring a taller fin, Boeing engineers installed the larger ventral fin. Later on, the surviving JT4-powered 707-200/300's were fitted with larger ventral fins to provide better stability control at cruise altitudes.
TWA 707-331 with a large ventral fin

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Photo © Bob Garrard
AF 707-328 in the original configuration before mods 1 year later.

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Photo © Mel Lawrence

The JT3D engines being broader and longer requiring a smaller or no ventral fin, like those found on the 707-100B, and -300B/C(for which it was an option)
TWA 707-331B with no ventral fin.

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Photo © Frank C. Duarte Jr.

BA 707-436

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Photo © Howard Chaloner

Quoting Scooter01 (Reply 5): The 420 was operated by BOAC (19), Lufthansa (5), ElAl (3), Air India (6) and VARIG (3)

Actually, BA/BOAC had 22 707-400's
20 707-436
02 707-465, G-AWRD/AWRE from Cunard/British Eagle

[Edited 2006-12-12 19:55:19]

While the ventral fins added more lateral area aft for stability, the ventral fins also prevented over rotation of the aircraft during take-off.