Boeing 7X7 aircraft

[Triton]

Model of Boeing 767 (7X7 Model 751) located in the Boeing Archives Bellevue, Washington.

In 1970, Boeing's twin-aisle 747 became the first wide-body jetliner to enter service. Two years later, the manufacturer began a development study, code-named 7X7, for a new wide-body aircraft intended to replace the 707 and other narrow-body jets. The aircraft would provide twin-aisle seating, but in a smaller fuselage than the existing 747, McDonnell Douglas DC-10, and Lockheed L-1011 TriStar wide-bodies. Development costs were to be shared with Italian corporation Aeritalia in Boeing's first major international joint venture. The initial 7X7 was conceived as a short take-off and landing airliner intended for short-distance flights, but customers were unenthusiastic about the concept, leading to its redefinition as a mid-size, transcontinental-range airliner. At this stage the proposed aircraft featured two or three engines, with possible configurations including over-wing engines and a T-tail. By 1976, a twinjet layout, similar to the one which had debuted on the Airbus A300, became the baseline configuration. The decision to use two engines reflected increased industry confidence in the reliability and economics of new-generation jet powerplants. While airline requirements for new wide-body aircraft remained ambiguous, the 7X7 was generally focused on mid-size, high-density markets. As such, it was intended to transport large numbers of passengers between major cities.[8] Advancements in civil aerospace technology, including high-bypass-ratio turbofan engines, new flight deck systems, aerodynamic improvements, and lighter construction materials were to be applied to the 7X7. Many of these features were also included in a parallel development effort for a new mid-size narrow-body airliner, code-named 7N7, which would become the 757.[9] Work on both proposals accelerated as a result of the airline industry upturn in the late 1970s. In January 1978, Boeing announced a major extension of its Everett factory—which was then dedicated to the manufacture of the 747—to accommodate its new wide-body family. The manufacturer also signed a risk-sharing agreement with the Civil Transport Development Corporation (CTDC), a consortium of Japanese aerospace companies, to share production responsibilities. By mid-1978, the new jetliner had received the 767 designation, and three variants were planned: a 767-100 with 180 seats, a 767-200 with 210 seats, and a trijet 767MR/LR version with 200 seats intended for intercontinental routes. The 767MR/LR was subsequently renamed 777 for differentiation purposes. The 767 was officially launched on July 14, 1978, when United Airlines ordered 30 of the 767-200 variant, followed by 50 more 767-200 orders from American Airlines and Delta Air Lines later that year. The 767-100 was ultimately not offered for sale, as its capacity was too close to the 757's seating, while the 777 trijet was eventually dropped in favor of standardizing around the twinjet configuration. In the late 1970s, operating cost replaced capacity as the primary factor in airliner purchases. In many ways the introduction of the Airbus A300 wide-body twin jet in 1972 hastened this development. As a result, the 767's design process emphasized fuel efficiency from the outset. Boeing targeted a 20 to 30 percent cost saving over earlier aircraft, mainly through new engine and wing technology. As development progressed, engineers used computer aided design for over one-third of the 767's design drawings, and performed 26,000 hours of wind tunnel tests. Design work occurred concurrently with the 757 twinjet, leading Boeing to treat both as almost one program to reduce risk and cost. Both aircraft would ultimately receive common design features, including shared avionics, flight management systems, instruments, and handling characteristics. Combined development costs were estimated at $3.5 to $4 billion. Early 767 customers were given the choice of Pratt & Whitney JT9D or General Electric CF6 turbofans, marking the first time that Boeing had offered more than one engine option at the launch of a new airliner. Both jet engine models had a maximum output of over 48,000 lbf (210 kN) of thrust. The engines were mounted approximately one-third the length of the wing from the fuselage, similar to previous wide-body trijets. The larger wings were designed using an aft-loaded shape which distributed lift more evenly across their surface span than any of the manufacturer's previous aircraft. The wings provided higher-altitude cruise performance, added fuel capacity, and expansion room for future stretched variants. The initial 767-200 would be capable of operating routes up to 3,850 nautical miles (4,430 mi) in length, surpassing a design target for sufficient range to fly across North America or across the northern Atlantic. The width of the 767's fuselage was set midway between the 707 and the 747 at 15 feet 6 inches wide. While it was narrower than previous wide-body designs, seven abreast seating with two aisles could be fitted, and the reduced width produced less aerodynamic drag. The adoption of a conventional tail design also allowed the rear fuselage to be tapered over a shorter section, providing for parallel aisles along the full length of the passenger cabin, and eliminating irregular seat rows toward the rear of the aircraft. However, the fuselage was not wide enough to accommodate two standard LD3 wide-body unit load devices side-by-side. As a result, a smaller container, the LD2, was created specifically for the 767. The original two-crew 767 glass cockpit features six CRT displays. The 767 was the first Boeing wide-body to be designed with a two-crew digital glass cockpit. Cathode ray tube (CRT) color displays and new electronics replaced the role of the flight engineer by enabling the pilot and co-pilot to monitor aircraft systems directly. Despite the promise of reduced crew costs, United Airlines initially demanded a conventional three-person cockpit, citing concerns about the risks associated with introducing a new aircraft. The carrier maintained this position until July 1981, when a U.S. presidential task force determined that a crew of two was safe for operating wide-body jets. The 767's two-crew cockpit was also applied to the 757, allowing pilots to operate both aircraft after a short conversion course, and adding incentive for airlines to purchase both types. As of August 2011, the 767 has received 1,057 orders from 71 customers, of which 1,007 have been delivered, and 837 are in service. The most popular variant is the 767-300ER, with 552 delivered, and Delta Air Lines is the largest operator, with 94 aircraft. Competitors have included the Airbus A300, A310, and A330-200, while a successor, the 787 Dreamliner, entered service in October 2011. Also of note, Boeing was experimenting with new house colors which eventually became the classic white fuselage with red and blue cheatlines of the 1980s and 1990s. Courtesy: Wikipedia

Source:
http://airchive.com/html/museums/boeing-archives-bellevue-washington-usa/boeing-767-7x7model-751-development-models/19107

 

[Triton]

Model of Boeing 777 tri-jet located in the Boeing Archives Bellevue, Washington.

The color livery on this Boeing 777 tri-jet model dates back to the late 1970s when the 767 and 757 were being developed. This model has very little to do with the final 777 program of the 1990s. The 777 as we know it actually began development in 1986 with a formal "go" in 1990.

Source:
http://airchive.com/html/museums/boeing-archives-bellevue-washington-usa/boeing-777-tri-jet-model-late-1970s/19115

 

[robunos]

In reply#34, above, in the images '19104', and '19052', the 7N7 model,
in addition to having the 'standard Boeing nose' appears to have a
tail end lifted straight from the 737...


cheers,
Robin.

 

[taildragger]

It's interesting that Boeing's thinking on how to arrange a trijet's #2 engine seemed to evolve. From the design freeze of the 727-100 (~1961) through the 7X7 trijet studies leading to the 767 (~1980), they seemed to favor a S-duct with a buried engine. By the time of 777 studies (~1990), the straight-through arrangement seemed to have prevailed. As far as I know, neither arrangement has a clear advantage in isolation and is closely inter-related to other aspects of the overall airplane configuration. Wonder what changed?

 

[taildragger]

The ease of re-engining was a consideration in 1975 also and I don't see why Boeing's thinking would have changed in that regard. I'm skeptical that a straight-thru arrangement makes this easier anyway. The DC-10 arrangement requires loads from the vertical fin to be carried around the engine/duct by very compact structures which would seem costly to rearrange. The L-1011 configuration doesn't require that these loads be so concentrated and probably allows for easier rearrangement even though it would take place within the fuselage.
As I understand it, the advantages of the L-1011 arrangement are:
- the rudder will tend to be closer to the rolling axis, reducing the rolling moment from rudder movement and simplifying control
- the engine is closer to the rolling axis, reducing roll inertia. This allows the wing engines to move outboard resulting in:
-- better span loading and so a lighter wing structure.
-- more room for inboard flaps so the flap pitching moment can be better balanced
-- more freedom in placement of the forward passenger doors
Also, the safety advantages of a podded engine are mitigated by the DC-10 arrangement since it's "strut" is part of the airframe's primary structure. McD mitigated it further by planting a pump serving all 3 hydraulic systems in the shrapnel plane of the #2 engine - but that was dumb engineering, not inherent to the configuration.

 

[gtg947h]

- the rudder will tend to be closer to the rolling axis, reducing the rolling moment from rudder movement and simplifying control
- the engine is closer to the rolling axis, reducing roll inertia. This allows the wing engines to move outboard resulting in:

Not really. Yes, you do get a small decrease in rolling moment from the rudder, but you also get to use a larger rudder and vertical tail. That is what lets you move the engines further out on the wing--you have more available yaw authority to handle an engine-out case. You can also (hopefully) use a single rudder panel, instead of the DC-10/MD-11 double-hinged one.

 

[Triton]

Photo of Boeing 757 model concept from 1978 found on eBay.

Source:
http://www.ebay.com/itm/1978-Boeing-757-artist-rendering-Press-Photo-/190704750762?pt=Art_Photo_Images&hash=item2c66e390aa

 

[Triton]

http://www.ebay.com/itm/1975-Boeing-7X7-Model-of-Proposed-7x7-Airliner-Press-Photo-/190704408759?pt=Art_Photo_Images&hash=item2c66de58b7
http://www.ebay.com/itm/1978-Boeing-767-typical-designs-studied-by-Boeing-Press-Photo-/200794607864?pt=Art_Photo_Images&hash=item2ec04a90f8
http://www.ebay.com/itm/2012-Boeing-7N7-Press-Photo-/190704373498?pt=Art_Photo_Images&hash=item2c66ddcefa
http://www.ebay.com/itm/1977-Boeing-7X7-Latest-Configuration-Model-Press-Photo-/190704407251?pt=Art_Photo_Images&hash=item2c66de52d3

 

[Triton]

Boeing 767-100 T-tail concept model photo found on ebay.

Source:
http://www.ebay.com/itm/2012-Airline-Boeing-767-Press-Photo-/271107713147?pt=Art_Photo_Images&hash=item3f1f47687b

 

[Triton]

Boeing 757 T-tail concept model in Eastern Airlines livery photo dated Sep, 1, 1978 found on ebay.

Source:
http://www.ebay.com/itm/1978-Airplane-Boeing-757-Press-Photo-/350649705439?pt=Art_Photo_Images&hash=item51a459e3df

 

[Triton]

Boeing 7X7 trijet concept model photo circa 1975 found on ebay.

Source:
http://www.ebay.com/itm/1975-Boeing-Aircraft-Co-iiaa-range-airliner-Wire-Photo-/390464917330?pt=Art_Photo_Images&hash=item5ae985cf52

 

[hesham]

Hi,


anther picture to its Model.

 

[uk 75]

Somewhere I have a picture of a model of the T tail in British Airways colours. Darned if I can find it. The lads at the British Airways Museum may still have the model in their collection.

 

[Triton]

Source:
http://airchive.com/html/museums/boeing-archives-bellevue-washington-usa/boeing-7x7-tri-jet-model-at-boeing-corporate-archives/29394

 

[hesham]

Hi,

here is the early concept for Boeing-777.

Civilni letadla 2

 

[hesham]

.. and there were twin- and four engined variants, too:
( from Aviation Week 1973 )

And from the same source;

http://archive.aviationweek.com/image/spread/19730416/13/2
http://archive.aviationweek.com/image/spread/19771107/23/2

 

[Triton]

Model of early 757 concept with T-tail from Boeing Images.

Source:
http://www.boeingimages.com/archive/Early-757-Concept-Model-with-T-Tail-2F3XC5OIYZR.html
http://www.boeingimages.com/archive/757-Concept-Model-2F3XC5OEUA8.html

 

[hesham]

Early Boeing-757 concept,a strange one;

http://www.boeingimages.com/C.aspx?VP3=SearchResult&VBID=2JRSN2PU5712WX#/SearchResult&VBID=2JRSN2PU5712WX&PN=4

 

[Yellow Palace]

Typo for 747, i could believe. It looks a lot like the Boeing CX-HLS contender. Possibly a typo?

 

[hesham]

Typo for 747, i could believe. It looks a lot like the Boeing CX-HLS contender. Possibly a typo?

No,read that on its tail "757".

 

[DWG]

I've just enlarged the image and I'm not convinced that's even a number between the 7s, it's certainly not identifiable as either 4 or 5. It could as easily be a * or other placeholder.

As already noted, it looks very much like the Boeing CX-HLS, but in a civil, double deck format, which very likely puts it pre-747.

Talking about the Boeing 7*7 development projects as though the middle number or letter is significant or fixed risks confusion. A project, or elements of a project, can start out in one weight class and market segment and end up in another entirely, with the name/designator changing as it goes. Look at the Sonic Cruiser and its evolution into the 787 as a very clear example. Boeing set out to make one aircraft, realised the airlines weren't on board with the concept, and jumped horses to something quite different midstream. For another example, Boeing's adoption of FBW was planned for 7J7 (short-haul, light twin), but ended up on the 777 (long-haul, big twin) instead, and got there via 757RT (which was an iron bird rig - RT = Rig Test). Wiki claims Bendix was the 7J7 FCS contractor, but 757RT and 777 FCS were GEC Avionics/BAE Systems Rochester and grew out of our 7J7 proposals (I joined the project fairly early in 757RT, but recall one of our technical gurus briefly discussing the evolution from 7J7 with me - though I think that might have been later on when we were both working on Typhoon).

And when 777 initial development wrapped up we all assumed we'd be moving straight on to a 777-derived 747 reworking/rewinging/re-FCS-ing, but Boeing never did settle on what they actually wanted to do with 747 and ended up stumbling into Sonic Cruiser instead. Boeing seemed to be absolutely certain that whatever Airbus market analysis were following was wrong, while not having a lot of confidence in their analysis of what they should do themselves.

If Boeing still have a model number system hidden behind the 7*7 then that would be a much clearer system for identifying projects, but if not then we really need to be tagging them as "1978 short haul narrowbody proposal" or "1992 747 rewinging with 777 technology" or whatever, not just 7*7.

 

[GeorgeA]

Slide is from the Boeing archives so the "757" tag seems quasi-official. They were a lot looser with designations in those days, witness the two or three Douglas/McD-D uses of "DC-10".

 

[hesham]

Sorry I sent it twice;

here is the solution;

http://www.secretprojects.co.uk/forum/index.php/topic,523.150.html

 

[Orionblamblam]

Nope, that is indeed a 757 (seven FIVE seven). I'm looking at some scans now... dating from August 1965, this series of 757 was clearly an early stab at what became the 747, but featured a range of design options. One, the 757-1104, featured *three* full decks.

Another one, 757-1111/1112 (domestic & international) is the passenger version of the (Boeing) C-5A, with a total of 674 passengers.

The illustration looks closest to the 757-3150, June 1965. Two full decks, one partial 747-like upper deck.

 

[hesham]

My dears,

it was not related to the later airliner series,but in Boeing sequence,that was the real
Boeing Model-757 appearance,this meant there was Model-756 before it,but the recently
one,it only followed the series (Model 707,717,727,737,747 & 757),can you understand
me ?.

 

[hesham]

From JAWA 1978;

 

[hesham]

From L+K 4/1975.

 

[hesham]

From Krila 6/1978.

 

[Cy-27]

To compliment posts #27, #47, #50 and #57 about the Boeing 7x7/757 twin engine, high-tail variant, please find attached a some images of this 757 type.

These are taken from a Boeing Preliminary Design briefing document dating from 1978 (Ref PD78).

The document stresses a great deal of commonality with 727 parts, stating that this version is a derivative of the 727-200. This aircraft would have a choice of three powerplants Rolls-Royce RB211-535, General Electric CF6-32 or Pratt & Whitney JT10D. Accomodation would be between 177-195 passengers.

Comparing the layout in Triton's post #27 (https://www.secretprojects.co.uk/threads/boeing-7x7-aircraft.3241/#post-67892) I think these images may be the same Boeing 757 Concept 227 mentioned there and in the Philip Birtles publication.

 

[jrlucariny]

View: https://youtu.be/0-GGlB6odsc

 

[Bill S]

LTV was in line for the subcontract work building the tail assemblies for the upcoming 757-767 series, there are a few artist concepts/models photos that made their way to the company. I just came across this T-tailed 757 in Texas International colors.

 

[publiusr]

T-tails improve the looks of twinjets, if nothing else. I don't remember any having them.

 

[Scott Kenny]

A small team kludged together a concept with cropped CFM56s on weird pylons, and a flattened inlet to get around the vacuum-cleaner problem. And we all knew it wouldn't amount to anything, because the only airline that bought it at first was some hayseed Texas outfit called Southwest...

The next time I'm in Seattle, I need to see if I can get some caricature stickers that Boeing makes. I really liked the 737 version, despite working on 727s.

T-tails improve the looks of twinjets, if nothing else. I don't remember any having them.

You need T tails when you have engines on the sides of the fuselage, like MD80s. You don't need T tails when your engines are on the wings.