Blackbird
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Did The DC-7 Have Any Influences...

Thu Aug 30, 2007 2:55 am

From the early DC-8 concept designs (the DC-7 first flew in '55 I think, and the first of the DC-8 concepts started in 1953...)?

Andrea Kent
 
timz
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RE: Did The DC-7 Have Any Influences...

Thu Aug 30, 2007 5:25 am

The DC-7 started airline service in 1953.
 
DH106
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RE: Did The DC-7 Have Any Influences...

Thu Aug 30, 2007 6:03 am

Are you talking here about the DC-7 as developed, or early conceptual "DC-7" designs?

The exisiting DC-7 is a much developed DC-4 / DC-6 design, stretched/pressurised, re-engined and with the 7C, a longer span. So for the existing 7, the answer has to be "no" since it's really just a derrived type.
...I watched c-beams glitter in the dark near the Tanhauser Gate....
 
Viscount724
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RE: Did The DC-7 Have Any Influences...

Thu Aug 30, 2007 12:19 pm

Quoting DH106 (Reply 2):
The exisiting DC-7 is a much developed DC-4 / DC-6 design, stretched/pressurised, re-engined and with the 7C, a longer span. So for the existing 7, the answer has to be "no" since it's really just a derrived type.

The DC-6 is pressurized.

Even the DC-7C wing is basically the same as on the DC-4 and DC-6 but attached to 5 ft. extensions from the fuselage to increase fuel capacity. It always amazed me that the original DC-4/C-54 wing could be used on significantly heavier DC-6 and DC-7 variants. I'm sure it was reinforced for the later models but the wing area was still the same except for the -7C due to the wing-root extensions.
 
aeroweanie
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RE: Did The DC-7 Have Any Influences...

Thu Aug 30, 2007 2:28 pm

Surprisingly, legend has it that the DC-7 had an influence on the 367-80 and 707. The story is that Boeing didn't know how high to place the aircraft on the landing gear, so they matched the door sill height of the DC-7. This resulted in a fairly short landing gear that made the 707 hard to stretch later on, due to take-off rotation angle limitations to avoid tail strike. On the other hand Douglas didn't follow the DC-7's sill height and opted for taller gear. As result, the DC-8 was easier to stretch. This resulted in the -61 and -63, which couldn't be matched by Boeing with the 707. If the McDonnell family hadn't lost their courage and shut down DC-8 production in 1972, these aircraft would have carried the DC-8 past the break even point.

When I get some time, I'll have to check if this is true...
 
411A
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RE: Did The DC-7 Have Any Influences...

Thu Aug 30, 2007 7:59 pm

Quoting Viscount724 (Reply 3):
It always amazed me that the original DC-4/C-54 wing could be used on significantly heavier DC-6 and DC-7 variants. I'm sure it was reinforced for the later models but the wing area was still the same except for the -7C due to the wing-root extensions.

It should not be all that surprising, as the DC-4 was designed from the beginning to be stretched.
The fuselage cross section was constant (unlike the Constellation) and the wing design selected was very efficient, for the time.
However, altho the wings look the same, there are slight variations.
Besides internal structural improvements to cater for the increases in weight, the wing wash out was changed, as well.

I know all this because a very close relative was the engineering project manager, DC-6/DC-7.
 
Viscount724
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RE: Did The DC-7 Have Any Influences...

Fri Aug 31, 2007 8:48 am

Quoting 411A (Reply 5):
Quoting Viscount724 (Reply 3):
It always amazed me that the original DC-4/C-54 wing could be used on significantly heavier DC-6 and DC-7 variants. I'm sure it was reinforced for the later models but the wing area was still the same except for the -7C due to the wing-root extensions.

It should not be all that surprising, as the DC-4 was designed from the beginning to be stretched.

Thanks for the further info. I expect part of it was also the traditional Douglas practice of building them like the proverbial tank.
 
SEPilot
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RE: Did The DC-7 Have Any Influences...

Fri Aug 31, 2007 9:08 am

Quoting AeroWeanie (Reply 4):
The story is that Boeing didn't know how high to place the aircraft on the landing gear, so they matched the door sill height of the DC-7.

It's amazing how such minor details have such far-reaching implications. Consider that if the 707 had been able to match the DC-8 stretch for stretch, the 747 might have never been developed. Juan Trippe was the driving force behind the 747, and he had been disappointed with the DC-8, and so was not interested in the stretched ones. If Boeing had been able to stretch the 707 Bill Allen might have told Trippe that that was all they could do, since they both were expecting the SST to make all existing aircraft obsolete in any case. But since that was not possible Allen agreed to build an all-new plane, and the rest is history. Funny how things work out.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
ImperialEagle
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RE: Did The DC-7 Have Any Influences...

Fri Aug 31, 2007 11:05 am

If the -7's had a strong influence it was all about speed----at least in the beginning. I know when I was young, to fly on a -7 was to ride in a hot-rod----at least the airline's PR people wanted us to think that. When the L-188's came along they pretty much trashed that idea. Oh yeah, a -7 could cruise at 400 mph, but you'd have to change-out all four engines when you were through.

When the jets were first proposed, the airlines and airframe manufacturers alike had a lot of concern over the transition the cockpit crews would have. Well, a lot of concern about just about every aspect of jet operation. Many of the airlines were adament about not changing things too drastically untill the pilots could adjust to the new flying techniques the jets would demand of them. So some airlines would demand the DC-8 had to land and take-off in about the same runway length as a -7C. Or that the landing approach had to be flown at a flight deck angle (nose-down) like the contemporary heavy recips did. (Convair didn't go along with all of this because they took the attitude that the jets were such a new ball game, it would be baptism-by-fire for everyone! The Convair Jets were already "flared" at the outer-marker and that didn't slow 'em down too much either!) I think it was Rickenbaker of Eastern that demanded the -8's land at the same speed as the -7's.

I don't think the -7's, in particular, had that much influence----IMO the airlines were just trying to fall on the conservative side when it came to such a radical departure from the "normal" piston types they had grown familiar with, which in those days were the DC-4/6/7 series by a wide margin.
"If everything seems under control, you're just not going fast enough!"

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