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Happy-flier
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Stretch DC-8 Fuselage Flex

Sun Oct 24, 2010 2:42 pm

For those who flew in Stretch DC-8s when they were still flying passengers -- can you relate what the famed fuselage flex was like for passengers on board? I've heard so many stories about this singular characteristic of the Stretch Eight as to make it easily the most often recounted DC-8 story of all time. People always commented on how the fuselage would twist and bend in flight, and this was apparently especially visible if you were in or near the last rows. Honestly, I have never seen something like this on any other airliner I've flown in. Lots of wing flex, yes; but no "fuse flex..."

As an aside, is it not true that the Stretch Eight, despite having a narrow fuselage, actually flew and felt more like a 767 than something smaller? If you look just at the dimensions (including wingspan) and operating weights, it seems to be much more in the class of a 767-300 than anything else that seats 6-abreast.

I can imagine that the large wings made it feel solid and stable in the air, not unlike most widebodies.

[Edited 2010-10-24 07:45:34]
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yenne09
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RE: Stretch DC-8 Fuselage Flex

Sun Oct 24, 2010 3:54 pm

I have traveled on both the 61 and the 63 and I never felt something like that. I flew aboard 63 of Nordair and Nationair and on the 61 of Minerve Canada. I flew regularly the stretched DC-8 between 1977 and 1991 from Montreal to Paris and back and sometimes we encountered severe turbulence over North Atlantic and the aircraft was always behaving correctly for me.
 
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kanban
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RE: Stretch DC-8 Fuselage Flex

Sun Oct 24, 2010 4:45 pm

on one flight out of SFO years ago, I was seated in the rear of steerage and when we encountered sever turbulence, looking forward up the aisle, the floor would appear to touch the ceiling then we'd flex the other way. there was some twist noticeable as well... plus many simple latched doors were popping open
 
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longhauler
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RE: Stretch DC-8 Fuselage Flex

Sun Oct 24, 2010 4:56 pm

Air Canada had a large galley complex in the middle if the Economy cabin of the DC-8-61 and DC-8-63, just behind the wing, dividing it into two. Urban legend stated they did this to avoid the passengers seeing the fuselage flex in turbulence. However, having sat on the aisle in the last row of the DC-8-61 it was noticeable if you looked down the aisle!
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Aesma
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RE: Stretch DC-8 Fuselage Flex

Sun Oct 24, 2010 9:36 pm

The longer A340s do that too, so much so that the alleys are always curtailed during flight.
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Starlionblue
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RE: Stretch DC-8 Fuselage Flex

Sun Oct 24, 2010 11:08 pm

I've seen a 757 fuse twist in turbulence. I was in the back and the aisle floor in front was clearly not parallel to the aisle floor in the back.
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Max Q
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RE: Stretch DC-8 Fuselage Flex

Mon Oct 25, 2010 4:39 am

Very noticable on the 753 and the MD80.
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access-air
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RE: Stretch DC-8 Fuselage Flex

Mon Oct 25, 2010 6:32 pm

I saw this happen from the last seat in an MD-80 taxiing out for takeoff at SFO....
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Viscount724
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RE: Stretch DC-8 Fuselage Flex

Mon Oct 25, 2010 8:28 pm

Quoting happy-flier (Thread starter):
For those who flew in Stretch DC-8s when they were still flying passengers -- can you relate what the famed fuselage flex was like for passengers on board? I've heard so many stories about this singular characteristic of the Stretch Eight as to make it easily the most often recounted DC-8 story of all time.

I flew on dozens of DC-8-61s and -63s on half a dozen carriers, including several flights that were quite turbulent, and I didn't notice that. I remember one YYZ-YMX-LIS flight on a CP Air DC-8-63 that was so turbulent after departure from YMX (Montreal Mirabel) they couldn't serve the meal until about 3 hours after takeoff. I think that story about the fuselage flex is an exaggeration.
 
411A
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RE: Stretch DC-8 Fuselage Flex

Mon Oct 25, 2010 8:50 pm

Quoting Viscount724 (Reply 8):
I think that story about the fuselage flex is an exaggeration.

Quite likely not.
Having been in the very back row of an Air Siam (all economy) stretched DC-8 ex-JKT some years ago, the fuselage twist was certainly noticeable, in moderate turbulence.
For those that bothered to look, of course.
 
aeroweanie
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RE: Stretch DC-8 Fuselage Flex

Tue Oct 26, 2010 4:21 pm

I rode on United Airlines' DC-8 Series 71s several times. I often ended up seated in the back and I remember that the fuselage deflection and twist in turbulence was very noticeable.
 
daviation
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RE: Stretch DC-8 Fuselage Flex

Thu Oct 28, 2010 5:27 pm

I was on six flights in the DC-8-63 and I never saw any flexing or twisting. Amusingly, I remember that if you were seated near the wings, it was a long walk back to the lavatory! Also, on one flight from JFK to LIS, we had a stop in Las Palmas, and the remaining passengers on the Las Palmas to LIS flight had to spread out to different seats because we were out of balance for takeoff.

Other than that, great flights and I still think the DC-8-63 was the most beautiful commercial aircraft ever produced.
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ajd1992
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RE: Stretch DC-8 Fuselage Flex

Thu Oct 28, 2010 5:47 pm

It's very noticeable on any aircraft that is long. The B757-300 is notoriously bad for it and I can vouch for it. It's almost vomit inducing!
 
Happy-flier
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RE: Stretch DC-8 Fuselage Flex

Fri Oct 29, 2010 12:12 am

@ daviation -- I agree, the DC-8-63 is my favourite of the Eights. Everything about it just says "elegance"...

I really wish I had made an effort to get on one as a passenger when they were still flying charters. Reason is, there is no other airplane quite like the Stretch Eight in design: six-abreast, yet so incredibly long. I bet that pilots needed extra training for ground handling such a long beast (especially in turns!!) and also to keep in mind rotation limitations. Just as an aside, I remember that Worldways (ex-CP Air) DC-8-63s would often take off with at least 30º flaps -- probably to facilitate a low-angle rotation. If you tried taking off in a Stretch Eight with, say, 10-15º flaps, I imagine that the risk of tailstrike would be quite high.

It would have been extremely interesting to feel what they were like on takeoff and in flight due to that long fuselage and those large wings that didn't have leading-edge slats. It must feel quite unlike most other aircraft due to its being a narrow body, but at the same time, having large dimensions and about the weight of a 767-300 series.

One wish of mine is that if someone filmed a flight from inside a Stretch Eight in the 1990s, when camcorders were already commonly available, they might post it on Youtube one day. I would love to see what it actually looked like and sounded like from inside the Stretch Eight.
May the wind be always at your back . . . except during takeoff & landing.
 
KevinL1011
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RE: Stretch DC-8 Fuselage Flex

Fri Oct 29, 2010 1:18 am

Quoting Viscount724 (Reply 8):
I flew on dozens of DC-8-61s and -63s on half a dozen carriers, including several flights that were quite turbulent, and I didn't notice that.

Same here. The fuselage is so long and narrow on a 61 or 63 series that when looking forward from the aft section, any movement in your line of sight (turbulence) is exaggerated. Sort of a telescopic or tunnel vision effect. I've always found the eight to be a solid airplane.

I will say that in my experience, the DC-10 had a ton of fuselage flex. I can remember on several flights seeing mid cabin dividers beating against the wall and overheads popping open on take off.

[Edited 2010-10-28 18:34:44]
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daviation
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RE: Stretch DC-8 Fuselage Flex

Fri Oct 29, 2010 4:10 pm

KevinL1011: the DC-10 had a ton of fuselage flex. I can remember on several flights seeing mid cabin dividers beating against the wall and overheads popping open on take off.

That's true! I was going to mention that. I used to take AA DC-10s quite often on the LGA-BUF run, of all places. In turbulence, I would often see buckling in the ceiling panels, and the overhead bins opened up more than once during the takeoff roll.

The DC-8-63s I was on (Capitol Int'l Airways and ONA) used A LOT of runway during takeoff. I have no idea what flap settings they used, but I recall wondering if we'd ever get off the ground.
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Happy-flier
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RE: Stretch DC-8 Fuselage Flex

Thu Nov 11, 2010 12:02 am

Quoting daviation (Reply 15):
The DC-8-63s I was on (Capitol Int'l Airways
and ONA) used A LOT of runway during takeoff. I have no idea what flap settings they used, but I recall wondering if we'd ever get off the ground.

This is very true. I used to notice the same thing watching them operate back in the day.

I think that the reason is pretty simple, and I attribute it to two causes: (1) the lack of full-span leading edge devices, necessitating a greater ground speed for rotation, and (2) a relatively low power -to-weight ratio. To illustrate this second point, let's compare the DC-8-63 against the 757-200ER:

DC-8-63:
4 x 19,000 lb = 76,000 lb / 350,000 lb MTOW

757-200:
2 x 42,600 lb = 85,200 lb / 255,550 lb MTOW

I used the higher weights and powerplant rating attributed to the -200 ER series here. Which ever way you look at it, the DC-8 carried way more weight, and had a hell of a lot less power to lift it into the air. Also, the 757 benefits from high-lift devices on the wings, which are lacking in the Eight.

How ever you look at it, the classic Stretch Eight only caught up in performance once the 22,000 lb st CFMs came on the scene.
May the wind be always at your back . . . except during takeoff & landing.
 
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longhauler
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RE: Stretch DC-8 Fuselage Flex

Thu Nov 11, 2010 4:57 pm

Quoting happy-flier (Reply 16):
DC-8-63:
4 x 19,000 lb = 76,000 lb / 350,000 lb MTOW

757-200:
2 x 42,600 lb = 85,200 lb / 255,550 lb MTOW


Using your figures, think of it another way.

With the loss of one engine 1 knot above V1, you are now faced with 57,000 lbs of thrust in a 350,000 lb aircraft in the DC-8, and 42,600 lbs of thrust in a 255,550 lbs aircraft with the B757. Although slightly, the ratio is better in the DC-8!

Airframe manufacturers always look to a worse case scenario, and engine loss at V1, is one of them. The advent of twins is not just that someone thought about the efficiency, it is that as engines become more and more powerful, the possibility now arises that you can build an aircraft that can (with the loss of one engine) carry 758,400 lbs from the runway at V1 to a safe altitude .... on one engine! (One of our B777-233/333s)

You tell that to some of our old DC-8 skippers, and they would think you are nuts!
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G650
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RE: Stretch DC-8 Fuselage Flex

Sun Nov 28, 2010 6:54 pm

Hello happy-flier,
Many years ago I was on board a Delta Stretch 8 out of Atlanta during a t-storm. During climb, there was some turbulence and without a doubt, being seated in the rear of the aircraft I did see one of the doorways at the most fwd bulkhead twist left to right and vise verse. It was pretty neat to see. I'm thinking that if it didn't shift , it would really load up the structure and cause damage.
 
ATLTPA
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RE: Stretch DC-8 Fuselage Flex

Thu Dec 23, 2010 4:08 am

Quoting G650 (Reply 18):
Hello happy-flier,
Many years ago I was on board a Delta Stretch 8 out of Atlanta during a t-storm. During climb, there was some turbulence and without a doubt, being seated in the rear of the aircraft I did see one of the doorways at the most fwd bulkhead twist left to right and vise verse. It was pretty neat to see. I'm thinking that if it didn't shift , it would really load up the structure and cause damage.

Agree completely!

In my case it was also a Delta Stretch 8, flying from Atlanta to Tampa in the mid-1980s. I was sitting in an aisle seat near the end of the aircraft and we went through a couple of patches of pronounced turbulence (it was summertime and we had some of those thunderstorms the South is famous for giving us that turbulence).

Nothing violent, but definitely a slightly perceptable flexing movement which could be felt and seenI

I disliked those "old" DC-8s back then, incidentally, and would have preferred to fly newer aircraft. How I wish that those DC-8s were back with the Delta fleet today, though! They beat a 757 any day!

ATLTPA
 
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DocLightning
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RE: Stretch DC-8 Fuselage Flex

Fri Dec 24, 2010 6:26 am

Quoting ATLTPA (Reply 19):

I disliked those "old" DC-8s back then, incidentally, and would have preferred to fly newer aircraft. How I wish that those DC-8s were back with the Delta fleet today, though! They beat a 757 any day!

When the 757 has been replaced with some sleek A320 NEO with sharklets or a 737RS, you will miss that 757.

In fact, in spite of how much I despise sitting on any plane for a long time (I know, heresy) I will very much miss the 757. The new planes just don't have the oomph.
-Doc Lightning-

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747400sp
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RE: Stretch DC-8 Fuselage Flex

Fri Dec 24, 2010 1:56 pm

Quoting DocLightning (Reply 20):
The new planes just don't have the oomph.




You got that right! Some people may disagree, but I think the 757 was the best 727 replacement ever made, because she a high performer like the the 727 was.
 
Viscount724
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RE: Stretch DC-8 Fuselage Flex

Fri Dec 24, 2010 9:35 pm

Quoting 747400sp (Reply 21):
I think the 757 was the best 727 replacement ever made, because she a high performer like the 727 was.

The 727 certainly wasn't a high performer when departing with a full load on routes like ORD-LAX/SFO/SEA. They were quite sluggish and seemed to take forever to lift off, especially 727-200s with lower thrust engine options as used by most US carriers.
 
DashTrash
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RE: Stretch DC-8 Fuselage Flex

Sat Dec 25, 2010 4:34 am

Quoting longhauler (Reply 17):
With the loss of one engine 1 knot above V1, you are now faced with 57,000 lbs of thrust in a 350,000 lb aircraft in the DC-8, and 42,600 lbs of thrust in a 255,550 lbs aircraft with the B757. Although slightly, the ratio is better in the DC-8!

You're not taking into account flex thrust takeoffs and APR / uptrim on the twin.

The DC-8 is using as much of that 19000 lbs as is available due to temperature / elevation on takeoff. The 757 is probably using less than 90% of it's 40,000 lbs, and the good engine may uptrim in single engine situations.

Both engines will lose power as density altitude climbs from 0, but newer design engines lose it slower than older ones. The 75 is getting more push than the 8 as a result.
 
ATLTPA
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RE: Stretch DC-8 Fuselage Flex

Sat Dec 25, 2010 2:46 pm

Quoting DocLightning (Reply 20):
When the 757 has been replaced with some sleek A320 NEO with sharklets or a 737RS, you will miss that 757.

In fact, in spite of how much I despise sitting on any plane for a long time (I know, heresy) I will very much miss the 757. The new planes just don't have the oomph.

You're probably right. And I will miss the Delta MD-88s eventually, too.

Of course, considering how good Delta TechOps is with maintaining aircraft and keeping them fresh-looking, I bet it will be quite some time before the DL 757s (or the MD88s) go away!

However, the DC-8's had more room in coach than the DL 757s do. Those 75s have been skimpy on seat pitch in coach since they were delivered. And there are only 2 engines (and engine starts), as opposed to the DC-8s 4 engines (and engine starts).

Oh, and as long as I am talking like a "foamer" here-- I still miss DL's L-1011s, too!

ATLTPA

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