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How Did The B-707 And DC-8 Influence Each Other?  
User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Posted (7 years 2 weeks 1 day 8 hours ago) and read 5912 times:

How did the B-707 influence the DC-8, and more interestingly, how did the DC-8 influence the B-707's design?

Andrea Kent

22 replies: All unread, jump to last
 
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17186 posts, RR: 66
Reply 1, posted (7 years 2 weeks 1 day 6 hours ago) and read 5902 times:

The big one I can remember is that the DC-8 was 6 abreast, while the 707 was originally planned as five abreast. Boeing realized their error and changed the fuse width of the 707 to allow 6 abreast.

That's why the 707 is wider than the (original) 717 (AKA KC-135). The military didn't need the extra width. Both are derived from the 367-80.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 2, posted (7 years 2 weeks 11 hours ago) and read 5830 times:

Starlion...


That's not exactly true...

The 367-80 was to be 5-abreast... so was the DC-8 initially. Juan Trippe asked that they widen the fuselage to 6-abreast, and both of them did. Boeing widened it's fuselage to 144 inches. Douglas chose 146 inches.

Boeing wanted the KC-135 and B-707 to have commonality with each, but with Douglas's wider fuselage [i](and the fact that the B-707's wing wasn't completed yet, and the USAF wanted the KC-135 to be able to fly at higher speeds for tanking purposes)[i], Boeing was forced to widen its design. They waited until Douglas had already committed to the 146-inch width, then widened theirs to 148.5.


Andrea Kent


User currently offlineViscount724 From Switzerland, joined Oct 2006, 26029 posts, RR: 22
Reply 3, posted (7 years 2 weeks 8 hours ago) and read 5802 times:



Quoting Blackbird (Reply 2):
Boeing widened it's fuselage to 144 inches. Douglas chose 146 inches.



Quoting Blackbird (Reply 2):
That's not exactly true...

The 367-80 was to be 5-abreast... so was the DC-8 initially. Juan Trippe asked that they widen the fuselage to 6-abreast, and both of them did. Boeing widened it's fuselage to 144 inches. Douglas chose 146 inches.

Boeing wanted the KC-135 and B-707 to have commonality with each, but with Douglas's wider fuselage [i](and the fact that the B-707's wing wasn't completed yet, and the USAF wanted the KC-135 to be able to fly at higher speeds for tanking purposes)[i], Boeing was forced to widen its design. They waited until Douglas had already committed to the 146-inch width, then widened theirs to 148.5.

Boeing's detailed dimensional drawings on their website have slightly different figures -- exterior fuselage width 148 inches for the 707 and 147 inches for the DC-8, with interior cabin width 139.3 inches for the 707 and 138.25 inches for the DC-8.


User currently offlineJetstar From United States of America, joined May 2003, 1665 posts, RR: 10
Reply 4, posted (7 years 2 weeks 3 hours ago) and read 5757 times:
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Juan Trippe of Pan AM was also playing Boeing against Douglas because he ordered both the 707 and DC-8 figuring that if one didn’t meet his design specifications he would order more of the other, I think he initially ordered about 20 of each.

User currently offlineBWilliams From United States of America, joined Sep 2007, 212 posts, RR: 0
Reply 5, posted (7 years 1 week 6 days 17 hours ago) and read 5710 times:

Regarding the DC-8 and the 707... why a narrowbody with 4 engines? Were they just not able to develop 2 engines that could produce enough thrust at the time, or was it due to a lack of ETOPS, necessating 4 engines for an overseas flight (did these two aircraft even have the range to complete a trans-Atlantic flight non-stop?)?


Regards, Brad Williams
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17186 posts, RR: 66
Reply 6, posted (7 years 1 week 6 days 15 hours ago) and read 5702 times:



Quoting Blackbird (Reply 2):
The 367-80 was to be 5-abreast... so was the DC-8 initially. Juan Trippe asked that they widen the fuselage to 6-abreast, and both of them did. Boeing widened it's fuselage to 144 inches. Douglas chose 146 inches.

Boeing wanted the KC-135 and B-707 to have commonality with each, but with Douglas's wider fuselage [i](and the fact that the B-707's wing wasn't completed yet, and the USAF wanted the KC-135 to be able to fly at higher speeds for tanking purposes)[i], Boeing was forced to widen its design. They waited until Douglas had already committed to the 146-inch width, then widened theirs to 148.5.

I see thanks.

Quoting BWilliams (Reply 5):
Regarding the DC-8 and the 707... why a narrowbody with 4 engines? Were they just not able to develop 2 engines that could produce enough thrust at the time, or was it due to a lack of ETOPS, necessating 4 engines for an overseas flight (did these two aircraft even have the range to complete a trans-Atlantic flight non-stop?)?

We're talking the early 60s. Engines were not powerful enough by a wide margin to allow a two engine aircraft in this weight class. ETOPS as a concept was still more than a decade away. If you had proposed crossing the Atlantic commercially with 2 engines they would have thought you were insane.

Besides, the widebody hadn't been invented yet.

And yes, some versions had transatlantic range.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineViscount724 From Switzerland, joined Oct 2006, 26029 posts, RR: 22
Reply 7, posted (7 years 1 week 6 days 13 hours ago) and read 5684 times:



Quoting BWilliams (Reply 5):
did these two aircraft even have the range to complete a trans-Atlantic flight non-stop?

The original 707-120 and comparable DC-8-10 models were primarily designed for transcontinental US service but could operate some shorter East Coast-Europe routes nonstop when winds were favorable, but they often required a fuel stop. The intercontinetal models of the 707 (the -320 and -420), and comparable DC-8-30/40/50 models which went into service a year or two after the original "domestic" models had significantly longer rqange and could certainly handle trans-Atlantic routes. The 707-320 was introduced on nonstop routes as long as LAX/SFO/SEA-Europe from around late 1959, and about a year later for the long-range DC-8 models.

Pan Am, the first 707 operator, bought 6 of the original -120 model (and later added two more used -120s) and operated them to Europe (often with a fuel stop) pending delivery of their first long range 707-320s. Pan Am's inaugural 707 flight from New York to Paris on October 26,1958 made a fuel stop at Gander.


User currently offlinePMN1 From United Kingdom, joined Jun 2007, 78 posts, RR: 0
Reply 8, posted (7 years 1 week 6 days 10 hours ago) and read 5659 times:



Quoting Viscount724 (Reply 7):
The original 707-120 and comparable DC-8-10 models were primarily designed for transcontinental US service but could operate some shorter East Coast-Europe routes nonstop when winds were favorable, but they often required a fuel stop.

I vaguely remember reading on another site that the Vickers VC-7 would have been capable of non stop flights from the start.


User currently offlinePMN1 From United Kingdom, joined Jun 2007, 78 posts, RR: 0
Reply 9, posted (7 years 1 week 6 days 8 hours ago) and read 5643 times:

If the USAF tanker/transport buy had been split 50/50 between the Boeing and the Douglas aircraft, how would that have affected each companies fortunes later?

User currently onlineStarlionblue From Greenland, joined Feb 2004, 17186 posts, RR: 66
Reply 10, posted (7 years 1 week 6 days 7 hours ago) and read 5629 times:



Quoting PMN1 (Reply 9):
If the USAF tanker/transport buy had been split 50/50 between the Boeing and the Douglas aircraft, how would that have affected each companies fortunes later?

Hard to say of course, but I don't think it would have had much long term effect. The procurement guys in the US tended to spread things around. So if you didn't get the primary contract, you'd get a subcontract.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineSEPilot From United States of America, joined Dec 2006, 7201 posts, RR: 50
Reply 11, posted (7 years 1 week 5 days 13 hours ago) and read 5546 times:



Quoting Jetstar (Reply 4):
Juan Trippe of Pan AM was also playing Boeing against Douglas because he ordered both the 707 and DC-8 figuring that if one didn’t meet his design specifications he would order more of the other, I think he initially ordered about 20 of each.

In fact he ordered 20 707's and 25 DC-8's, which was a huge blow to Boeing.

Quoting Blackbird (Reply 2):
Boeing wanted the KC-135 and B-707 to have commonality with each, but with Douglas's wider fuselage [i](and the fact that the B-707's wing wasn't completed yet, and the USAF wanted the KC-135 to be able to fly at higher speeds for tanking purposes)[i], Boeing was forced to widen its design. They waited until Douglas had already committed to the 146-inch width, then widened theirs to 148.5.

Boeing had already committed to the fuselage for the KC-135 and had started production on it when they made the decision to widen the 707. I don't know the exact dimensions, but I believe that the 707 was still 5 abreast, and Boeing not only had fewer orders from Pan Am but was losing out on domestic orders to the DC-8 when Bill Allen made the decision to widen the fuselage again (the Air Force had wanted a wider fuselage than the 367-80, and Boeing intended it to be the same as the 707, enabling the same tooling to be used.) I do know that the decision to widen the 707 fuselage over the KC-135 was enormously expensive; the KC-135 at that time had 25 orders and the absolute ironclad guarantee from the Air Force that no more orders for it would ever be forthcoming, as Lockheed had won the contract but Boeing could deliver sooner, hence the 25 (thanks to Curtis LeMay.) Boeing was able to end up with a wider fuselage than the DC-8 because by that time the DC-8 design was frozen.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineLTU932 From Germany, joined Jan 2006, 13864 posts, RR: 50
Reply 12, posted (7 years 1 week 5 days 8 hours ago) and read 5506 times:



Quoting Starlionblue (Reply 6):
We're talking the early 60s. Engines were not powerful enough by a wide margin to allow a two engine aircraft in this weight class. ETOPS as a concept was still more than a decade away. If you had proposed crossing the Atlantic commercially with 2 engines they would have thought you were insane.

Just to add, when the 707 and DC-8 were being designed, the engine type of choice for jet powered aircraft was the Turbojet. It wasn't until the late 50's/early 60's that the Rolls-Royce Conway, the very first commercial turbofan engine, entered service, which was probably also the time when the TF-33/JT3D was being designed as a turbofan derivative of the J-57/JT3C to replace the old turbojets on the 707 and DC-8.

I guess when the 747 entered service, the over 45000 lbs per engine on the high-bypass JT9D-3 were a giant leap over the 13,000 lbs or up to 18,000 lbs of thrust of the "standard" low-bypass turbofans of the time. Once the high-bypass turbofan was developed, that's when longer range, twin-engine aircraft could become reality.


User currently onlineStarlionblue From Greenland, joined Feb 2004, 17186 posts, RR: 66
Reply 13, posted (7 years 1 week 5 days 7 hours ago) and read 5497 times:



Quoting LTU932 (Reply 12):
I guess when the 747 entered service, the over 45000 lbs per engine on the high-bypass JT9D-3 were a giant leap over the 13,000 lbs or up to 18,000 lbs of thrust of the "standard" low-bypass turbofans of the time. Once the high-bypass turbofan was developed, that's when longer range, twin-engine aircraft could become reality.

True. And even the 747 engines were a real stretch with delays that threatened EIS. State of the art and just slightly beyond.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 14, posted (7 years 1 week 5 days 5 hours ago) and read 5482 times:

How wide would the cabin interior of the DC-8 if it had the thinner skin the 707 or even CV-880 had (Anybody know the thicknesses of either? In either case they're thinner)

Andrea Kent


User currently offlineLTU932 From Germany, joined Jan 2006, 13864 posts, RR: 50
Reply 15, posted (7 years 1 week 4 days 22 hours ago) and read 5449 times:



Quoting Starlionblue (Reply 13):
True. And even the 747 engines were a real stretch with delays that threatened EIS.

But in the end, that 3 month delay, courtesy of Pratt & Whitney, didn't stop the Queen of the Skies from becoming the best selling widebody ever.  Wink

Now that legacy may be broken by the 777, which is coming close to the 1000 mark and the first commercial aircraft ever to hit the 100000 lbs thrust per engine range. This proves that sometimes, it's not so much the aircraft itself, but the engine that is a gamechanger.


User currently onlineStarlionblue From Greenland, joined Feb 2004, 17186 posts, RR: 66
Reply 16, posted (7 years 1 week 4 days 19 hours ago) and read 5431 times:



Quoting LTU932 (Reply 15):
This proves that sometimes, it's not so much the aircraft itself, but the engine that is a gamechanger.

So true.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineSEPilot From United States of America, joined Dec 2006, 7201 posts, RR: 50
Reply 17, posted (7 years 1 week 4 days 18 hours ago) and read 5428 times:



Quoting Blackbird (Reply 14):
How wide would the cabin interior of the DC-8 if it had the thinner skin the 707 or even CV-880 had (Anybody know the thicknesses of either? In either case they're thinner)

The skin itself isn't that thick (on the order of a quarter of an inch); it's the structure that the skin is attached to that makes up the thickness of the sidewalls. I don't think there was much difference between the three there.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 18, posted (7 years 1 week 4 days 14 hours ago) and read 5403 times:

Dear SEPilot,

Really? I did not know that.


Andrea Kent


User currently offlineSEPilot From United States of America, joined Dec 2006, 7201 posts, RR: 50
Reply 19, posted (7 years 1 week 4 days 13 hours ago) and read 5394 times:



Quoting Blackbird (Reply 18):
Really? I did not know that.

Well, that's the purpose of this forum. By the way, I enjoy your posts; you often come up with interesting questions that spark good exchanges. Keep it up!



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3607 posts, RR: 66
Reply 20, posted (7 years 1 week 4 days 12 hours ago) and read 5367 times:



Quoting LTU932 (Reply 15):
Now that legacy may be broken by the 777, which is coming close to the 1000 mark

Total sales for the 777 now stand at 1013.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offline737tdi From United States of America, joined Sep 2007, 933 posts, RR: 2
Reply 21, posted (7 years 1 week 3 days 12 hours ago) and read 5304 times:
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Blackbird: I have answered some of your questions on the DC8 and this one is going to be fairly vague (due to my lack of sheetmetal engineering knowledge.) There is a very big difference in the mindset of these two great companies, as far as structure goes. Douglas used a fairly thick skin with sacrificial finger doublers at the skin joints (flex points). Boeing decided to overlap thier skins. I can't say Douglas ever had a "Aloha failure". They did have some other major structural failures but none due to fatigue. I believe the Douglas influence has been absorbed by Boeing and they have incorporated some very positive aspects of structural design into thier new aircraft. For what it's worth.

737tdi


User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 22, posted (7 years 1 week 2 days 5 hours ago) and read 5220 times:

What's a sacrificial finger doubler / flex-point? Is that like a butt-joint?

What's the advantage and disadvantages of flex-points and what are the advantages and disadvantages of overlapped skins?


Andrea Kent


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