Old 707's (was:Re: Compressor Stall at Takeoff?)

Date:         17 Dec 97 03:43:06 
From:         john@pegase.demon.co.uk (John Wright)
Organization: Janet, me and our cat in our little cottage
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On 10 Dec 97 04:05:02 Gerard Foley wrote:

>  Way off the point:
>When I first rode in a TWA707 from O'Hare to Philadelphia, probably around
>1957, I thought the takeoff run was the longest I had ever experienced.
>   Later on 707's seemed to get off the ground fairly easily.  Were they
>re-engined or something to improved the initial acceleration?

The 707 entered service in October 1958... if you flew in a 707 about
then it could only have been a 707-100 series (actually a 131 for TWA)
with  P&W JT3C-6 engines giving 12,500 lbs static thrust. These were
straight turbojets essentially similar to the military J57 - as used on
B-52's upto the B-52G. The first B series 707 went into service in 1960,
these were (among other improvements) fitted with JT3D-1 engines giving
17,000 lbs thrust. Thus you got a considerable increase in available
take off power. The JT3D (known by the USAF as the TF-33) was basically
a J57 with the first three compressor stages removed and two 53 inch
diameter "fan" stages added and an additional turbine stage, to convert
a straight turbojet to a turbofan with a 1.4 bypass ratio and around 20
percent lower fuel consumption than the basic J57. To quote from Peter M
Bowers, take off run was considerably reduced, rate of climb range
(about doubled! - 2,400 ft/min -> 5,050 ft/min...) and maximum speed
increased. The JT3D was used on all B model 707's, and made possible the
first proper intercontinental version, the 707-320B which entered
service in 1962.

John Wright