Quoting warden145 (Reply 83):
I thought I heard that Boeing wasn't willing to participate in the CFM56 re-engine program specifically because they were more interested in pushing the 757 and 767? Whatever I heard is almost certainly 3rd or 4th hand info, so you may well be right. Is there anyone around who was directly involved with the program who can shed some light on it?
Looks like Boeing didn't want Cammacorp doing the 707s in 1982 (link 1), but I have some Boeing sources from 1979-1980, all of them confirm Boeing's effort to push the conversion, e.g. "Boeing News" Vol. 38, No. 40, from October 25, 1979:
A week from tomorrow will be rollout day for a new 707 that Brian Davis believes will convince a lot of airlines around the world of the advantages of re-engining their 707s with quieter, more fuel-efficient and more powerful jets.
Discussions of the re-engining are presently under way with several airlines, Davis said.
Forbes McRae, 707-700 program manager, said the conversion will be limited to current Advanced 320B and C models. There are no plans to offer the 707-700 as a brand-new airplane.
Approximately 500 of the Advanced 320 airliners are in service around the world, according to BCAC sales support engineer Floyd Baldwin.
"We expect," Davis said, "that the re-engining will be attractive to airlines that have a requirement for the long, thin route and are very sensitive to capital investment and airplane-mile costs." By "long, thin route," Davis said he meant flights of intercontinental length where widebody capacity is not needed. "There has been a lot of interest regarding extending the life of the 707," Davis said.
With 160 passengers and their baggage in one mixed-class configuration, the CFM56-powered 707 would have a 5,250-nautical-mile range, 10-percent greater than the 4,750-nautical-mile range of the 707 with its original JT3D engines."
Other articles, including ones from flight testing on Jan 31, 1980, indicated that everything was going well for the program and that they were planning to have initial testing done by April 15th.
Quoting Tan Flyr (Reply 86):
Quoting warden145 (Reply 83):
I recall reading a third reason why the re-engining didn't happen on the civilian 707's. The Air Force was very interested in buying up as many civilian 707's as possible for spare parts for their C-135 and C-137 fleets. For that matter, I recall that being the primary reason why we didn't see nearly as many pax 707's converted to freighters as we did with DC-8's.
Yes, I believe that is fairly correct. I seem to recall from AA
and TWA annual reports in the early/mid 80's that frames were sold to the USAF
. Seems that one time taking off out of TUS
, flying over Davis-Monthan I saw a bunch of old TWA 707 parked. I'm not 100% sure that is where it was..so don't hold me to it.
But yes I am pretty sure a number of the TWA & AA
707s, all 300's I think, went to the USAF
Yes, the resale on the 707s was higher due to the military interest in re-engining the KC
-135As with the fans and turning them into KC
-135Es. There were a number of them with weird turbocompressor configurations because they just bolted on what was in stock that day.
To sum up the above, it looks to me like the DC-8-70s beat the 707-700 for two reasons:
1. The stretch-8s had higher capacity and thus were a more valuable asset because they would recoup the sunk costs sooner in revenue service (very few -62s were converted)
2. Demand for the 707 engines, pylons, and other parts was high because of USAF KC
-135 re-engining, so it was probably more lucrative to part them out
Returning to the DC-8-70 range discussion:
Quoting cougar15 (Reply 5):
Funny Story to that, a Pilot once told me that the ´60´s with the conversion were good enough to follow a 747SP around the world and still have the legs to carry on after the (PW powered) 747SP needed a fuel stop!I have no idea if that is true
I dug up another article on the topic, you're right! The caveat is that they were investigating putting an extra 5,000 gallons in. (link 2)
Quoting LH707330 (Reply 60):
Quoting mayor (Reply 42):
I recall the company telling us that the DC-8-71s were getting 25% better fuel economy than what the -61s got.
I wonder how they computed that. I recall reading in Boeing documentation about the CFM56 707s that they would get a 14% savings, and it was essentially the same mod. Perhaps the 25% came after flight tests.
Yes, that looked to be an early projection in 1980 (link 1). In 1982, they were saying 15-17% (link 2), which jives with the Boeing numbers.
Quoting maxpower1954 (Reply 74):
Jane's 1970-71, but I made a mistake and referenced the non-fan -320, big difference! You are right, thanks for the correction!
The -320B and the -62 were very close, with the -62 being a little longer legged I believe.
That makes sense. The JT3D fans were 13% more efficient than the straight-pipes, and the CFM56 another 14%. If the CFMs gave a 10% range boost, figure the same for the initial conversion and you get your 20%.
Link 1: http://www.flightglobal.com/FlightPDFArchive/1982/1982%20-%202417.PDF
Link 2: http://www.flightglobal.com/pdfarchive/view/1980/1980%20-%203266.html
Edit: The forum gave me a 403, so the formatting got messed up
[Edited 2015-01-26 23:05:29]