Hello

I read in this month Airways magazine, that Douglas was looking into installing GE CF-6s on DC-8s. Do anybody here, knows about this, and if it had been done, what would have likely been the out come?

Source

Airways February 2016 edition

THE DOUGLAS DC-8 (II)

AIRWAYS SPECIAL

Page 65

Never heard of that. When were they considering it? Was it for a new version?

I assume two of them, not four?

DL replaced the 1st/2nd gen jet engines on its DC8 60-series a/c in the 80s with some kind of high bypass ratio engines, but don't know the manufacturer.

[Edited 2016-02-05 14:04:02]

Quoting GSPSPOT (Reply 3): DL replaced the 1st/2nd gen jet engines on its DC8 60-series a/c in the 80s with some kind of high bypass ration engines, but don't know they manufacturer.

these engines are CFM56 built by a joint venture between SNECMA in France and General Electric.

Quoting GSPSPOT (Reply 3): DL replaced the 1st/2nd gen jet engines on its DC8 60-series a/c in the 80s with some kind of high bypass ration engines, but don't know they manufacturer.

Those were CFM-56s, and the DC-8s became DC-8-73s with that re-engine.

SpaceshipDC10 beat me to the punch by minute.

[Edited 2016-02-05 14:02:07]

[Edited 2016-02-05 14:02:18]

Quoting GSPSPOT (Reply 3): DL replaced the 1st/2nd gen jet engines on its DC8 60-series a/c in the 80s with some kind of high bypass ration engines, but don't know they manufacturer.

CFM 56

The -60 series had the option to be re-engined in the early 80's. I think a bit over 100 planes received the upgrade.

Quoting treebeard787 (Reply 5): Those were CFM-56s, and the DC-8s became DC-8-73s with that re-engine.

Delta's DC-8s at the time were -61s, thus they became -71s. However following that same way, there were -72 and 73s too. If my memory is right, 110 series 60 in all were converted to 70s.

Wonder if there are still flying DC-8's around. NASA's one is probably still flying but that's about it I think?

I assume this would have been a new derivative, probably first considered in the early '70s If it had been built, the lighter 757 would have put it out of business within a decade. The structural modifications to convert existing DC-8s to a twin-engine configuration would almost certainly have been prohibitive.

In the late seventies, many of the DC- 8-60´s series operators were looking for the possible ways of the life extension of their -61, -62, and -63 series of DC-8. The first carriers who began a joint study of re-engine options were United, Flying Tigers and Delta (all together 78 x -61s, 10 x -61CFs, 51 x -62s, 10 x -62CFs, 6 x -62AFs, 41 x -63s, 53 x -63CFs, 7 x -63AFs and 6 x -63PFs were built).

In the 1977, some of the retired McDonnell Douglas executives formed Cammacorp as a contractor for DC-8´s conversions and retrofitting projects. They selected the GE / SNECMA CFM56 engine to power the next generation DC-8s, and Grumman Aerospace was contracted to supply the engine nacelles and the redesigned pylons that were required for the new engine.

This modernized version of the DC-8-61 series featured the new low-noise, advanced technology General Electric / SNECMA engine, an entirely new interior, as well as new air conditioning, instruments and avionics equipment. The first converted aircraft was the United Airlines´ DC-8-61. Work began in the October 1980, and the aircraft was redesignated to the DC-8-71. In the April 81 the FAA awarded the -71 type certificate, and the certificates for the -72 and -73 followed shortly.

The first conversion for Delta was done by the conversion manufacturer Cammacorp, and the other 12 by DL, at Delta's Technical Operations Center in Atlanta. The airline completed its entire DC- 8-71 conversion and modernization program in early 1984 (42.000 work hours each). Otherwise, Delta introduced the world's first DC- 8-71 passenger service on April 24, 1982, when Flight 910 departed from Atlanta shortly after 12:30 pm en route to Savannah, Georgia.

In the March of the 1981, Cammacorp acquired a United Airlines DC-8-62 for its first -72 conversion. The aircraft was configured as an executive aircraft for a large corporation.

The DC- 8-71s were powered by four CFM56- 2C1 engines, each 22.000 lb s.t. - 97,9 kN. They were some 13 decibels quieter than the previous power-plants. The aircraft also used 20% less fuel. The DC- 8-61s were powered by four PW JT3D-3B engines, each 18.000 lb s.t. - 80,1 kN. The most powerful engines installed on the DC- 8s were CFM 56- 2C5s (68,3˝ fan) with 24.010 lb s.t. - 106,8 kN….

In the 1986, the Super 70 conversion program had reached its final stages. All together 110 aircrafts had been converted - 53 x -71s, 7 x -72s and 50 x -73s. Conversion operations were done by:

- Cammacorp (at McDonnell-Douglas facilities in TUL) - 44 conversions
- Delta - 48 conversions
- Air Canada - 9 conversion
- UTA - 9 conversion

The final conversion was the one of the series -72 and that for the NASA (MSN 46082, LN 458). Like the other -72s and this one is powered by four CFM56- 2C1 engines...


Nice regards

Mario

A CF6 wouldn't have fit, without adding 12 feet to the landing gear.

Would a CF6 fit under the wing? The early CF6 had a fan 15 inches larger than the early CFM56.

Thanks for the history mfranjic, I never knew the details of that reenginging.

The CF-6 and the CFM56 are two very different engines. If the CF-6 was being considered for the DC-8, it must have been quite a bit before the CFM56 was developed.

Not to mention .... put 4 CF-6s on the wing of a DC-8, with more than twice the power of a CFM56 and almost three times the power of what the DC-8 originally came with ... and the damned thing would climb almost vertical!

Quoting longhauler (Reply 14): Not to mention .... put 4 CF-6s on the wing of a DC-8, with more than twice the power of a CFM56 and almost three times the power of what the DC-8 originally came with

Obviously they thought of putting only 2 CF-6s on the DC-8 in the early 70s, but they closed the production line in 1972 instead to concentrate on the DC-10. They were also worried that further DC-8 availability would cannibalize DC-10 demand.

Quoting MEA-707 (Reply 15): Obviously they thought of putting only 2 CF-6s on the DC-8 in the early 70s,

Do you have any reference for this? I've never heard of a McD DC-8 twin proposal

Quoting Spacepope (Reply 16): Do you have any reference for this? I've never heard of a McD DC-8 twin proposal

Terry Waddington who worked at the DC-8 program wrote a great book on the DC-8 in 1996, on page 93 "A promising alternative was to install de-rated CF-6s, used on the DC-10, at a cost of over $10 million per ship set, but the engines were considered too powerful and expensive at the time." I admit he must have meant 4 of these weaker engines, as 2 would be a perfect power match, but would bring other complications like wing rework. I always had in my mind that Douglas even looked at building new 2 engined DC-8s, which would have become a heavier 757 lookalike, but I can't find official sources for that. For sure Waddington would have mentioned it in the book, for instance in the chapter on pag 84 about the closing of the program. Probably what if discussions mixed with facts in my memory.

[Edited 2016-02-06 08:22:06]

Good evening,

this is a, to my mind, very interesting thread. These DC-8 were/are great planes. While I am not able to judge the technical or economical aspects, I was much more impressed by the DC-8 "appearance" than that of the 707.

However, CF6ing the DC-8 would have made it a somewhat "symmetric" mirror of the 343. While the latter is too large of a plane, esthetically, not technically, if compared to the size of its engines, the CF6 on the wings of a DC-8 would have appeared rather fat, I assume.
Moreover, wasn't the DC-8 one out of a number of very few, only, plane types, which could operate the engines in reverse mode while flying? It allowed impressive braking maneuvers, if I recall correctly, like approaching the runway very fast and then slowing down at a huge rate to get the right speed for touchdown. I am not sure whether this ability was kept active when the planes were CFM56ed, and I am not sure whether it would have been possible with a CF6. Although: If it worked on the old P&Ws, why not on the CF6s?

Best,

Ferroviarius

Will we see a DC-8 equipped with a CFM Leap-X?

Quoting Bralo20 (Reply 8): Wonder if there are still flying DC-8's around. NASA's one is probably still flying but that's about it I think?

There are still private ones out there. Any cargo?

A related thread on DC-8s:

The DC-8 Family (by Airspeed772 Jan 19 2015 in Civil Aviation)

Quoting pjc747 (Reply 19): Will we see a DC-8 equipped with a CFM Leap-X?

Hah, wouldn't that be cool if NASA did something like that with theirs?

https://www.airliners.net/photo/DHL-%...d=d9cf0dc16805b7807988d722cf6a49c3

Still got a few of the CFM56 equipped DC-8's sitting at IGM. I am sure that they could be available for the right offer. I think you would have to start with the extended gear though!

Mike

I worked on the program. Airborne Express was the interested party and McDonnell Douglas was involved. What killed it was that Vmca had to increase a lot.

Quoting Ferroviarius (Reply 18): I was much more impressed by the DC-8 "appearance" than that of the 707.

I can relate to that, and Boeing kind off matched that appearance with the 757.

Quoting cschleic (Reply 20): Any cargo?

I seem to remember reading on Skyliner the sale/lease or transfer of one -71(F) or -73(F) to an African airline.

Quoting aeroweanie (Reply 23): What killed it was that Vmca had to increase a lot.

With that sleek elegant tail, VMCa has always been a bane of the DC-8.

Two engine approaches, with two out on one side was a difficult balance between speed and power, and ... there was a point in time with a speed, power and configuration set up where landing was now the only option. The advent of simulators saved a lot of pilots and airframes which had previously been lost doing such an exercise.

Four 737-300 engines strapped to the DC-8 back in the days of the Super-70s is about as simply put as you can get to describe the powerplants.

Quoting lat41 (Reply 26): Four 737-300 engines strapped to the DC-8 back in the days of the Super-70s is about as simply put as you can get to describe the powerplants.

Except that the DC-8 re engining programme was much earlier, and didn't need the squashed nacelles to fit the engine under the wings of the 737!