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Why No Streched 707?  
User currently offlineSEPilot From United States of America, joined Dec 2006, 6910 posts, RR: 46
Posted (7 years 8 months 2 days 15 hours ago) and read 4944 times:

I asked this question on another topic but received no answer, so I'll ask it here. The DC-8 acheived extraordinary life because it was stretched; I think I read somewhere that the reason the 707 was not stretched was that the tail configuration was such that stretching it would have caused the tail to strike the runway on takeoff. Does anyone have any info on this?


The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
32 replies: All unread, showing first 25:
 
User currently offlineDtwclipper From , joined Dec 1969, posts, RR:
Reply 1, posted (7 years 8 months 2 days 14 hours ago) and read 4909 times:

From what I have read, the biggest drawback was the landing gear structure. It was comparatively short and would have had to be completely redesigned to stretch the aircraft.

User currently offlineSEPilot From United States of America, joined Dec 2006, 6910 posts, RR: 46
Reply 2, posted (7 years 8 months 2 days 14 hours ago) and read 4905 times:

Quoting Dtwclipper (Reply 1):
From what I have read, the biggest drawback was the landing gear structure. It was comparatively short and would have had to be completely redesigned to stretch the aircraft.

Thanks; that makes sense.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineTjwgrr From United States of America, joined Mar 2000, 2444 posts, RR: 2
Reply 3, posted (7 years 8 months 2 days 13 hours ago) and read 4799 times:

Not to the extent that the DC-8 was stretched, but the 707 was stretched... called the -300/-400 series.

Quoting SEPilot (Thread starter):
The DC-8 acheived extraordinary life

Technically not a 707, but lots of these still around:


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User currently offlineSparkingWave From South Korea, joined Jun 2005, 671 posts, RR: 0
Reply 4, posted (7 years 8 months 2 days 13 hours ago) and read 4791 times:

There wasn't a stretched 707 because Boeing decided to go for a bigger plane altogether, the 747, to satisfy the projected increases in passenger demand for the 1970s.

The 707 basically came out in 1959, and the 747 got the go ahead in 1967, less than 10 years later.

SparkingWave ~~~



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User currently offlinePictues From Canada, joined Nov 2004, 246 posts, RR: 0
Reply 5, posted (7 years 8 months 2 days 13 hours ago) and read 4774 times:

the landing gear and the Tail would have needed re-designing, just look at the tail of the non-stretched DC-8's they look too big for the size of aircraft, Douglas did that in mind of future stretches of the aircraft

User currently offlineRedFlyer From United States of America, joined Feb 2005, 4329 posts, RR: 28
Reply 6, posted (7 years 8 months 2 days 12 hours ago) and read 4737 times:

Quoting SEPilot (Thread starter):
I think I read somewhere that the reason the 707 was not stretched

The 707-300 series was in fact 8 feet longer than the original 707. But as others have pointed out, the landing gear and tail configuration probably kept it from being stretched further. That and the fact that, as SparkingWave has mentioned, Boeing went for something completely different and bigger in the form of the 747.



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User currently offlineFrancoBlanco From , joined Dec 1969, posts, RR:
Reply 7, posted (7 years 8 months 2 days 12 hours ago) and read 4736 times:

Boeing decided to abandon the 707 program in favor of the 747. A larger 707 could have killed off some orders for the 707.
Douglas had no plans for a widebody as an answer to the 747, so they stretched the DC-8. A bit later, Douglas realised that it was indeed necessary to build a widebody, too, so they came up with the DC-10.

In the end, Boeing was much more successful. Even with the stretched versions, the production of the Dc-8 ended in 1972 after 556 units produced.
Including all military versions, 1010 707s were built until 1983. Furthermore, about 750 units of the 747 classic were built, compared to 446 DC-10s.

The 707 definately had the potential to be stretched. The redesigns of the landing gear etc. were feasible, there was simply no demand for it with the 747 in mind.

Sebastian


User currently offlineTjwgrr From United States of America, joined Mar 2000, 2444 posts, RR: 2
Reply 8, posted (7 years 8 months 2 days 12 hours ago) and read 4708 times:

707-600

Would have looked good:


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Direct KNOBS, maintain 2700' until established on the localizer, cleared ILS runway 26 left approach.
User currently offlineN501US From United States of America, joined May 2005, 220 posts, RR: 0
Reply 9, posted (7 years 8 months 2 days 12 hours ago) and read 4704 times:
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I am just adding a few thoughts to those mentioned in regards to 747. Although it did not have the seating capacity, the 727-200 with its 3 engines filled a niche for domestic US carriers. The DC10 and L1011 seating capacities were close to what a 707 stretch would be. Plus the planning, design, and subsequent delivery of 757s probably diminished the desire to stretch the 707, too.


Fools and thieves are well disguised in the temple and the marketplace.....
User currently offlineBeech19 From United States of America, joined Jul 2006, 936 posts, RR: 4
Reply 10, posted (7 years 8 months 2 days 8 hours ago) and read 4513 times:

Quoting Tjwgrr (Reply 3):
Technically not a 707, but lots of these still around:

Not a 707 at all. Not even close. Different fues, different wing, similar tail but a little different, ect. In fact they basically shared nothing other than a similar look... and many of the KC-135E's had TF33's stolen from 707's.
KC-135's were Dash-80's and came a good time before the 707.



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User currently offlineAirbusA6 From United Kingdom, joined Apr 2005, 2013 posts, RR: 0
Reply 11, posted (7 years 8 months 2 days 2 hours ago) and read 4349 times:

There's a big capacity difference between even a 'stretched' 707 and a 747, one wonders if it could have filled a gap until the launch of the 767 a decade later?


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User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 12, posted (7 years 8 months 2 days 2 hours ago) and read 4331 times:

Quoting Dtwclipper (Reply 1):
From what I have read, the biggest drawback was the landing gear structure. It was comparatively short and would have had to be completely redesigned to stretch the aircraft.

 checkmark  That is correct, the size of the gear was the largest limitation for stretching the 707.


User currently offlinePygmalion From United States of America, joined Jun 2006, 966 posts, RR: 37
Reply 13, posted (7 years 8 months 2 days 1 hour ago) and read 4291 times:

And wheel wells etc. The aircraft has to be high enough off of the ground that when you stretch it, there is enough room to allow rotation and get enough angle of attack on the wing to lift off the runway at a decent rate without tail strikes. The 707 was close enough to the ground that another stretch would have had the tail dragging. The 757 had tall enough gear that it could take a very long stretch, but even then it got a tail skid.

User currently offlineStirling From Italy, joined Jun 2004, 3943 posts, RR: 21
Reply 14, posted (7 years 8 months 2 days ago) and read 4198 times:

Quoting N231YE (Reply 12):
the size of the gear was the largest limitation for stretching the 707.

In addition to a new wing and flap design plus, bigger, stronger engines.
Serious studies to stretch the 707 from the -320/-420 began in earnest in 1965.

-620
Domestic services
27 foot stretch to 180 feet.
Seating capacity increased to 230.
MGTOW 330,000lbs (I know some of you are scratching your heads, as this was the same as the -320/-420)
The -620 would have kept the wings and engines of the -320/-420, severely limiting it's intercontinetal capabilities.

-820
42 foot stretch to 195 feet.
9 foot increase in wingspan to 155 feet.
Seating capacity increased to 275.
MGTOW 410,000lbs.
And then of course the aforementioned landing gear extensions and flap design.

-700
One example built. No examples extant.
(Actually the designation was applied to an existing -320C frame)
Four CFM56 attached.
More economical, quieter, and more powerful....nothing came of a civilian version.
The CFMs were stripped off, JT3Ds attached, and sold to Morrocco in 1992 as the last 707.

Of course, that model lived on in a way as the foundation of the E-3 or E-6....or, retrofits to the KC-135A, which became the KC-135R.

The commentary as to why Boeing did not undertake the 707 upgrades will go on forever within the neophyte world, but the fact remains this:

In 1965, Boeing was busier than a ten-pecker rooster in a hen house.
They delivered 61 707s that year, and 83 the next, next to 727s and assorted birds for the military. The 747 programme was kicking off....
Boeing was the Airbus of it's generation.

Just like Airbus is making a quantam jump from A340 capacity to A380 capacity, ignoring the big whole between the A321 and A332....Boeing was doing the same in 1965, leaving the segment for 175 to 350 seats to McDonnell-Douglas primarily with the stretch -8s, and soon the -10, and to Lockheed with the possessed L1011.

Don't forget, the Convair 880/990 programs weren't dead...yet, at best they acted as a pressure valve to the demand for the less thirsty but slower 707s and DC-8s. (But who doesn't love a HotRod.....Even with kerosene 9 cents a gallon, they were not long for this world.)

But most importantly....the industrial spies were coming back from Europe with crazy talk of this most-unholy thing called an A300!

It took the Boeing engineers almost 10 years to take the A300 concept seriously. Is there a parallel here to today's enviroment? Hmmmmm.

The British on their own were fiddling with a 200+ seat extenstion of the Trident and VC10 which never went anywhere....that double deck VC10 was especially hideous, proposals flew around airline headquarters at the very same time Boeing was pitching inferior 707 stretches. One anectdote has them waiting in the lobby at BOAC at the very same time....poor bastards.

So there you have it. While easy to slap a sentence to a question and call it an "answer"....it's not always that easy, there are always mitigating factors that have roots in many places, which I find much more interesting!

Edited for grammar.

[Edited 2007-01-24 03:45:59]


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User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 15, posted (7 years 8 months 2 days ago) and read 4180 times:

Quoting Stirling (Reply 14):

Interesting...I never knew that Boeing was designing stretches of the 707 (although the shorter landing gear was a major problem with stretching the 707).

However, one could say that a few of the early 747 concepts did include a "707-like" aircraft, only much different looking.

[Edited 2007-01-24 03:44:59]

User currently offlineDw747400 From United States of America, joined Aug 2001, 1260 posts, RR: 1
Reply 16, posted (7 years 8 months 2 days ago) and read 4175 times:

A major reason for the 747 was the landing gear issues on the 707. Any 707 derivative would have been a major undertaking, so the "low-cost" approach to meet higher capacity needs wasn't as quick and cheap as Boeing would have liked. Combined with pressure to not only make a DC-8 length 707, but something even bigger, the 747 emerged as the best option.

Quoting Beech19 (Reply 10):
KC-135's were Dash-80's and came a good time before the 707.

Well, if you want to get technical there are a lot of difference between the Dash 80 and the KC-135. Nonetheless, KC135s, and 707s all grew out of the same program (Dash 80).



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User currently offlineJasond From Australia, joined Jul 2009, 23 posts, RR: 0
Reply 17, posted (7 years 8 months 1 day 23 hours ago) and read 4103 times:

Quoting RedFlyer (Reply 6):
The 707-300 series was in fact 8 feet longer than the original 707. But as others have pointed out, the landing gear and tail configuration probably kept it from being stretched further. That and the fact that, as SparkingWave has mentioned, Boeing went for something completely different and bigger in the form of the 747.

Agreed, looking at the -300 for example it looks about as stretched as it could realistically be so the landing gear issue is a sound argument. What about the 737 though. I know between the -200 and what we now call the 'classics' involved some design changes but on first appearence not to the landing gear configuration as it applies to the fuselage. Extend that further into the NG world, were the changes to the landing gear so significant to allow a subsequent stretch of the 737 to a -900? Or were there a different set of issues at work here?


User currently offline747400sp From United States of America, joined Aug 2003, 3624 posts, RR: 2
Reply 18, posted (7 years 8 months 1 day 23 hours ago) and read 4095 times:

Quoting Stirling (Reply 14):
-700
One example built. No examples extant.
(Actually the designation was applied to an existing -320C frame)
Four CFM56 attached.
More economical, quieter, and more powerful....nothing came of a civilian version.
The CFMs were stripped off, JT3Ds attached, and sold to Morrocco in 1992 as the last 707.

Of course, that model lived on in a way as the foundation of the E-3 or E-6....or, retrofits to the KC-135A, which became the KC-135R.

There was also the still born E-8B.


User currently offlineBeech19 From United States of America, joined Jul 2006, 936 posts, RR: 4
Reply 19, posted (7 years 8 months 1 day 10 hours ago) and read 3930 times:

Quoting Dw747400 (Reply 16):
Well, if you want to get technical there are a lot of difference between the Dash 80 and the KC-135. Nonetheless, KC135s, and 707s all grew out of the same program (Dash 80).

Far less differences between the Dash-80 and the KC-135 than a Dash-80 and 707 (much larger, heavier ect, 100% different fues, wing ect after it was all said and done.).

The KC-135 ended up being basically a IGW Dash-80. It used the same fues, wings ect, with more powerful engines (slightly).



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User currently offlineSEPilot From United States of America, joined Dec 2006, 6910 posts, RR: 46
Reply 20, posted (7 years 8 months 1 day 10 hours ago) and read 3920 times:

Quoting Beech19 (Reply 19):
The KC-135 ended up being basically a IGW Dash-80. It used the same fues, wings ect, with more powerful engines (slightly).

The KC-135 was wider than Dash-80, which had an oval shaped fuselage; the KC-135 was round. Boeing had planned on using the same fuselage as the KC-135 for the 707 but when the DC-8 offered 6 abreast seating and customers started flocking to it they redesigned it and made it what it is now.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineScouseflyer From United Kingdom, joined Apr 2006, 3390 posts, RR: 9
Reply 21, posted (7 years 8 months 1 day 10 hours ago) and read 3917 times:

Quoting Stirling (Reply 14):
The British on their own were fiddling with a 200+ seat extenstion of the Trident and VC10 which never went anywhere....that double deck VC10 was especially hideous, proposals flew around airline headquarters at the very same time Boeing was pitching inferior 707 stretches. One anectdote has them waiting in the lobby at BOAC at the very same time....poor bastards.

Is that in addition to the BAC 3-11 which was killed by the A300?


User currently offlineBeech19 From United States of America, joined Jul 2006, 936 posts, RR: 4
Reply 22, posted (7 years 8 months 1 day 9 hours ago) and read 3866 times:

Quoting SEPilot (Reply 20):
The KC-135 was wider than Dash-80, which had an oval shaped fuselage; the KC-135 was round.

Yes the Dash-80 and KC-135 have different widths but are both oval and the fues's are based off the same design, just increased proportionaty. They increased the height for the -135 and hence received a wider fues but still smaller than the 707's future fues. It was NOT round. Do some reading...

I have personally spent A LOT of time around -135's (55-3120 FISTA and 55-3135 FISTA II before they were retired) and they are oval for sure.
The 707 could NOT compete using the Dash-80 style fues and that is why they needed to build a new fues for the 707 (as you mentioned about the DC-8) as it couldn't compete using a smaller oval one.

Do those look round or oval?

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Trust me... if you ever get to look head on to a -135, do it... they are drastically ovaled actually.



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User currently offlineRikkus67 From Canada, joined Jun 2000, 1647 posts, RR: 1
Reply 23, posted (7 years 8 months 1 day 9 hours ago) and read 3863 times:

Jasond...re: 737 landing gear

Take a look at front-on pictures of a -300 to a -700. You will notice that the engine nacelle is more rounded on the -700. When the NG series came out, Boeing redesigned the wing, and tail...both are noticably larger. Among improvements was the length of the landing gear, to accomodate longer fuselage lengths.


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-300


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-700

note the difference in the landing gear (the -700's is "beefier"), as well as the tail height, and the rounder intake on the -700

back on topic....

When the CFM's were attached to the 707, there must be minimum ground clearance? What I mean to say: Is there a clearance difference between the 707, and the KC135's in regards to CFM engine installation (knowing only the last civil 707 had the CFM's temporarily)....



AC.WA.CP.DL.RW.CO.WG.WJ.WN.KI.FL.SK.ACL.UA.US.F9
User currently offlineStirling From Italy, joined Jun 2004, 3943 posts, RR: 21
Reply 24, posted (7 years 8 months 1 day 9 hours ago) and read 3808 times:

Quoting Rikkus67 (Reply 23):
Is there a clearance difference between the 707, and the KC135's in regards to CFM engine installation

The bottom of the inboard engines of the 707s were about 5 feet from the ground; outboard engines higher.

When the CFM56s were attached the clearance was reduced to around 3 feet....about the same as the 737-300.



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25 A999 : The 707 wing was swept back more than the DC-8's and this limited the amount of stretch possible, as there would be tailstrikes if the fuselage had be
26 Post contains images Scouseflyer : Have you photo-shopped a bigger tail onto that plane as it looks massive
27 SEPilot : You are correct; I had never looked that close; I'm not sure why I thought it was round. I knew the 707 was; I just assumed it for the KC-135. Thanks
28 Post contains links and images Rikkus67 : SEPilot... If you compare front-on shots of the 707,727,737,757... you will notice that the upper lobe on all are the same*, while the lower lobe vari
29 SEPilot : Could it be because it would have raised more issues with certification and pilot type ratings? Thanks for the photos, by the way.
30 JAM747 : The 737-900 looks close to the length of some of the 707s to the point where it looks like a twin 707. I wonder if this will the last stretch of the
31 Viscount724 : Off topic, but it's often overlooked that the longest Boeing narrow-body type prior to the 757 was the 727-200 which is 3 inches longer than the 707-3
32 Jasond : According to Boeing (look under Out of Production Models) they quote the length of the 707-320B as 152 feet 11 inches. Using the same source they quo
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