wdleiser
Posts: 865
Joined: Thu Apr 22, 2004 9:32 am

Update My DC-8!

Sun Nov 27, 2005 2:13 pm

What is the CASM for a DC-8?

I mean, what if we were to put brand new highly extremely efficient engines on a DC-8 (there are more efficient ones than CFM's!)

How many people did the DC-8 seat? What was its range? Its payload?

I mean, I think it could replace the 757.... just rebuild it, with new engines and lighter material.
 
DLKAPA
Posts: 7962
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RE: Update My DC-8!

Sun Nov 27, 2005 2:30 pm

With 4 engines you will never see a DC-8 replace a 757. UA did just the opposite.
And all at once the crowd begins to sing: Sometimes the hardest thing and the right thing are the same
 
kanebear
Posts: 852
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RE: Update My DC-8!

Sun Nov 27, 2005 2:46 pm

If this were even remotely feasable, it would've been done already.
 
AY104
Posts: 451
Joined: Sun Nov 27, 2005 8:35 am

RE: Update My DC-8!

Sun Nov 27, 2005 3:02 pm

I am extremely keen on the DC-8, my alltime favourite aircraft. I worked for Finnair in the early 70's, at SPL, and we had a flight to JFK operated with a DC8 series 62. This version was slightly longer than the older series 20, 30, 40 and 50. I do remember that it sometimes was an all-economy version and could hold up to 198 pax, but that was in charter config. This was also a combi, so it was even heavier than the regular DC8, due to the stronger frame, especially the floor to accomodate cargo pallets. Even at that, it could still fly LAX/SFO/YVR to HEL nonstop. I believe in the 80's, Finnair purchased a non-combi DC8-62 the flew to Tokyo from HEL nonstop and other Asian markets.
Also, I flew many times on Canadian Airlines on the DC8-63 series (known as the "Stretch 8"), from AMS nonstop to YVR. On a hot summer day, that would use almost the entire runway in AMS with a full load. They would also do charter flights YVR LGW with the stretch, although I am not sure that they changed the configuration to All Y-class. Eventually, some airlines re-engined the stretch, to save fuel, but even at that they were phased out of scheduled service many years ago. It is a wonderful aircraft, my introduction to the jet age. Flew from AMS to YVR in 1962, just after CPA (Canadian Pacific, later known as Canadian Airlines) inaugurated jet service on that route. At that time you could still fly the Britannia, at a reduced fare, which took over 20 hours via YYC/YEG and a refuelling stop in Sondrestrom, Greenland - but what an experience at 13 years of age to fly over the Pole!
Hope this helps answer your questions.
My first aviation posting - I love this website!
AY104
The only thing a customer should expect for his/her loyalty is good service
 
wdleiser
Posts: 865
Joined: Thu Apr 22, 2004 9:32 am

RE: Update My DC-8!

Sun Nov 27, 2005 3:21 pm

What is the CASM for the DC-8?

Still need that answered!

and what is the 757's CASM?

What was the fuel usage of a DC8 and that of a 757.

What engines could fit on the DC-8?

Someone actually answer the questions!

And thanks AY104 for your experiences!`
 
broke
Posts: 1299
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RE: Update My DC-8!

Sun Nov 27, 2005 11:33 pm

One thing to realize about the re-engined DC-8's is that their operating weights did not change. With the more fuel efficient engines they could fly further or operate with more payload on shorter route unless the Zero Fuel Weight (ZFW) limit was reached. The Gross Take Off Weight, the ZFW, and Maximum Landing Weight did not change because there was no beef up of the airframe and landing gear to accommodate increases in these areas.
No matter how far below the Gross Take Off Weight (GTOW) you are, once you reach the ZFW, you cannot add anymore payload.
Still the re-engined DC-8's were more economical and more flexible to operate.
Even more the airplane is a dilemma, because with the CFM-56 engines the airplane can meet the proposed Stage 4 noise limits.
 
md80fanatic
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Joined: Tue Apr 13, 2004 11:29 pm

RE: Update My DC-8!

Sun Nov 27, 2005 11:43 pm

Who said it STILL has to be a four engined plane?

Why not just cap the outer pylons and plumbing...and replace the two inner engines and pylons with something larger and more efficient? That could be done.

While they are at it...they can re-engine all the DC-9s and MD-80s too.
 
md90fan
Posts: 2798
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RE: Update My DC-8!

Sun Nov 27, 2005 11:47 pm

Quoting DLKAPA (Reply 1):
With 4 engines you will never see a DC-8 replace a 757. UA did just the opposite.

DL did too  Smile
http://www.devanwells.blogspot.com/
 
lat41
Posts: 457
Joined: Mon Jun 28, 2004 12:23 pm

RE: Update My DC-8!

Sun Nov 27, 2005 11:47 pm

An outfit called Cammacorp if I have it right was the company that did the conversion of DC8-60s to the 70's with the CFMs. I understand there avionics and other engineering upgrades. That company is long gone by now. If an operator had DC8s with a lot of life left in them today, and looked to convert,is there any entity that could handle the task? There must be used CFMs around as well. With the cost of new aircraft, it might be as crazy as it sounds if there were enough airframes to work on.
 
UPS Pilot
Posts: 828
Joined: Tue May 18, 1999 1:17 pm

RE: Update My DC-8!

Mon Nov 28, 2005 7:57 am

Nobody stated that the 8 still has a flight engineer as well. The cost of upgrading and refitting to a two man crew would be outragous. UPS is retiring the 8 and had bought all the tooling and equipment from Cammacorp for the 70 series. All of UPS 8's were 70 series and is the largest operator of the type. The cockpicks were upgraded to semi glass with ins. Spares are dwindling and maint is nickle and diming especially with the landing gear.
 
GQfluffy
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RE: Update My DC-8!

Mon Nov 28, 2005 8:28 am

Quoting MD80fanatic (Reply 6):
Who said it STILL has to be a four engined plane?

Why not just cap the outer pylons and plumbing...and replace the two inner engines and pylons with something larger and more efficient? That could be done.

If only all things in life were that simple.... From an engineering view, what you've proposed is going to take alot of $$$. From a physical view, I'm not sure the airframe could handle the changes in stress points going from 4 engines to 2. From a realistic view...ARE YOU NUTS????  eyebrow 
This isn't where I parked my car...
 
andaman
Posts: 2271
Joined: Wed Oct 05, 2005 5:29 am

RE: Update My DC-8!

Mon Nov 28, 2005 9:36 am

Quoting AY104 (Reply 3):
I believe in the 80's, Finnair purchased a non-combi DC8-62 the flew to Tokyo from HEL nonstop and other Asian markets.

AY104

Actually AY started their regulary Asia service to Tokyo with DC-10 (polar route, with extra fuel tanks).

I have nice memories of a charter flight on AY's DC-8, as a little boy (1978) I flew from HEL to Vancouver.
Chinese cookie in SFO: "You're doomed to a life of forever travelling abroad and to be able to afford it!"
 
milesrich
Posts: 1508
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RE: Update My DC-8!

Mon Nov 28, 2005 11:58 am

The DC-8 Design could have been used to engineer a 757 type twin just as the 707/727 evolved into the 757; however, McDonnell Douglas was trying launch the MD-80 and had problems with the DC-10, and was not about to take on an almost entirely new design, ie, landing gear, wing, rear stabilizer, etc. By the time Boeing brought out the 757, Douglas was really not designing new airplanes. But that being said, Douglas built a more robust design than Boeing, and the eights and nines will be around for a long time to come.
 
md80fanatic
Posts: 2365
Joined: Tue Apr 13, 2004 11:29 pm

RE: Update My DC-8!

Mon Nov 28, 2005 12:28 pm

Quoting GQfluffy (Reply 10):
From an engineering view, what you've proposed is going to take alot of $$$.

4 new engines would cost alot too.

Quoting GQfluffy (Reply 10):
From a physical view, I'm not sure the airframe could handle the changes in stress points going from 4 engines to 2.

2 engines producing the thrust of the previous 4 should weigh less than the previous 4 in total. Where is the added stress when a load is removed?. I think the DC-8 could handle something like this, no problem.

Quoting GQfluffy (Reply 10):
From a realistic view...ARE YOU NUTS????

Absolutely not.
 
broke
Posts: 1299
Joined: Wed Apr 24, 2002 8:04 pm

RE: Update My DC-8!

Mon Nov 28, 2005 8:35 pm

Changing the DC-8 from a 4 engine airplane to a 2 engine airplane has been looked at.
There is internal structure in the wings at the pylons that carry the loads to and from the pylons into the wing. If you were to use that existing structure you would end up with either an airplane with the engine too close to each other for safe engine out performance or too far out. In addition, the DC-8 uses slots at the pylons as part of its lift augmentation for low speed flight. The aerodynamic interaction between the pylon and the slot is part of this configuration.
To place 2 engines at the optimum location would require major structural modifications to the wings, which would difficult to do on an assembled wing plus you would lose lift from the slots.
The glass cockpits were installed to improved the reliability of the navigation systems on the airplane, not to try to make it a 2 man cockpit.
Air Canada tried to develop a 2 man DC-8 cockpit, with assistance from Douglas, and ended up with a 3 man crew in a weirdly configured cockpit.
 
Shenzhen
Posts: 1664
Joined: Wed Jun 25, 2003 12:11 pm

RE: Update My DC-8!

Mon Nov 28, 2005 8:48 pm

Quoting Broke (Reply 14):
Changing the DC-8 from a 4 engine airplane to a 2 engine airplane has been looked at.
There is internal structure in the wings at the pylons that carry the loads to and from the pylons into the wing. If you were to use that existing structure you would end up with either an airplane with the engine too close to each other for safe engine out performance or too far out

I thinks you got the backward. You want the engines as close as possible to the fuselage for engine outs, but as far away from the fuselage as possible due to the noise they generate.

Anyway, bring it back... we can rename it the DC20 and get Airbus to spin it as an all new airplane to replace the A310 LOL

Cheers
 
BrowntailWhale
Posts: 182
Joined: Thu Oct 18, 2001 5:17 am

RE: Update My DC-8!

Tue Nov 29, 2005 4:28 am

Actually ABX air in the early 1990's was dead serious on doing a twin engine conversion of their DC-8's. It was to use two CF-6's. They even went so far as to purchase an ex-Saudia 50 series to use as a mockup. ABX was doing ALL of the engineering in house and they didn't realize the problems that removing the outboard engines would have on the structural integrity of the outer wing. The final nail in the coffin was when Douglas found out about their plans. Douglas went ballistic when they heard about it and vowed to fight ABX tooth and nail with the FAA to block approval. ABX finally gave up on the project.
 
BrowntailWhale
Posts: 182
Joined: Thu Oct 18, 2001 5:17 am

RE: Update My DC-8!

Tue Nov 29, 2005 4:32 am

Quoting UPS Pilot (Reply 9):
Nobody stated that the 8 still has a flight engineer as well. The cost of upgrading and refitting to a two man crew would be outragous. UPS is retiring the 8 and had bought all the tooling and equipment from Cammacorp for the 70 series. All of UPS 8's were 70 series and is the largest operator of the type. The cockpicks were upgraded to semi glass with ins. Spares are dwindling and maint is nickle and diming especially with the landing gear.

You are misinformed. UPS has NO plans to retire the DC-8. In fact next summer UPS will be using every spare DC-8 in the system to fly the extra Menlo volume. The ONLY thing that will force UPS to park the DC-8 is lack of spares. UPS has sold two DC-8's that were broken up for spares.
 
UPS Pilot
Posts: 828
Joined: Tue May 18, 1999 1:17 pm

RE: Update My DC-8!

Tue Nov 29, 2005 10:44 am

Browntail,

So you mean to tell me that all of the original 49 are still in system? 7 of them are out of the system so far. I guess I'm misinformed. What Menlo flying? We still haven't seen a flight from Menlo yet and nothing is going to happen anytime soon.
 
N62NA
Posts: 4006
Joined: Sun Aug 10, 2003 1:05 am

RE: Update My DC-8!

Tue Nov 29, 2005 11:07 am

I love the DC-8 - it's truly a graceful looking bird. Had the good fortune to see one fly over the beach here in Miami Beach yesterday on approach to MIA. Was a -73 and that thing is just beautiful to look at!

Hooray for the cargo airlines!
 
User avatar
VirginFlyer
Posts: 3940
Joined: Sun Sep 10, 2000 12:27 pm

RE: Update My DC-8!

Tue Nov 29, 2005 3:03 pm

Quoting MD80fanatic (Reply 13):
2 engines producing the thrust of the previous 4 should weigh less than the previous 4 in total. Where is the added stress when a load is removed?. I think the DC-8 could handle something like this, no problem.

This question about turning a quad into a twin pops up fairly often. The major problem isn't so much the total weight of the engines, but the positioning of that weight. The engines under the wing provide what is called bending relief.

Try to picture the forces acting on an aircraft in flight. Lets stand behind the aircraft, and look at the left hand wing. At the wing root, there is a clockwise bending moment produced by the lift from the wings. The weight of the engines produces an anticlockwise moment. Thus the overall bending moment at the root is reduced. So, if you place two larger engines on the inboard pylons, you reduce the anticlockwise moment (remember, a moment = force x distance). Thus, the net moment is increased. Thus, the structure of the wing has to be strengthened to resist this increased moment. This is complicated and costly.

If we fit the engines to the outboard pylons, then we run into problems with the aircraft setting empty on the ground - this time, there is more anticlockwise moment in our wing than it had been designed for. There is also the issue, as mentioned above, of unacceptable performance with an engine out.

If we fit the engines at a position which gives ideal bending relief at the root, we now have them in a place on the wing which wasn't designed to carry them, meaning more complicated and costly structural changes are necessary.

Whichever way you look at it, unless the aircraft has been designed from the outset to be both a twin and a quad, it will be very difficult and expensive to change from one configuration to the other. Even starting from a clean sheet, it will be rather difficult to come up with a design which works as both a twin and a quad. That is why the wing of the A330/340 is such a great piece of engineering work.

Let's go back to the original suggestion of new engines. I think it is safe to say we will not see a third re-engining program for the DC-8 to produce a new passenger aircraft. However, the DC-8 is still a workhorse freighter, and I don't believe it is beyond the realm of logic to say a DC-8-70 with new engines could be built. Now, the question is, will a re-engined DC-8 be cheaper to acquire and operate than a converted 757/767/A300/A310? It will all come down to how many of these aircraft end up on the second hand market over the next decade, and at what price.

So could the DC-8 get a third lease on life? Of course. Will it? That is the question. Personally, I would be dubious if enough demand will exist to justify the certification of a re-engining program. I think there will be enough of the 1980s twins coming on to the second hand market, with the advantage of existing certification for freighter conversions. Nonetheless, the DC-8 in its various forms will continue flying freight for years to come.

V/F
"So powerful is the light of unity that it can illuminate the whole earth." - Bahá'u'lláh
 
clipperhawaii
Posts: 1943
Joined: Sun Dec 26, 1999 3:35 pm

RE: Update My DC-8!

Tue Nov 29, 2005 4:32 pm

Love the 8.


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