US Supersonic Transport (SST) Program 1960-1971

[KJ_Lesnick]

Blackkite,

I'm not trying to sound dumb here, but those images look to me just like the B2707-100? Is there a length difference (like the canarded version)?


Kendra Lesnick

 

[Caravellarella]

Dear Kendra, I believe the two images show the first iteration of the Boeing 2707-100; the version with a more swept-back tailfin (with a vertical trailing edge) and the six-abreast seating in the area-ruled forward fuselage. I understand the second iteration went to seven-abreast twin-aisle seating in a wider area-ruled forward fuselage, and this is the pre-canard version available as a very basic 1/200 kit from Revell.

Terry (Caravellarella).

 

[KJ_Lesnick]

Okay, so the 7-abreast wide-body without canards is actually a -200? Is it the same length as the later canarded -200?


Kendra Lesnick

 

[Caravellarella]

Dear Kendra, to the best of my knowledge the canarded Boeing 2707-200 was longer, and the canards were requried to make a the longer aircraft more controllable. There is another post on Secretprojects which describes the design evolution in detail, but I cannot find it for the moment. Please ignore my captions on the 2 images I've posted as they may be wrong.

The two non-canarded versions appear to be very similar except for the shape of the tail-fin and the width of the area-ruled forward fuselage.

Terry (Caravellarella)

 

[Skybolt]

The last throngs of the -200 are very complex, and not all the configuration were made public (outside Boeing-FAA I mean). Before discarding the canard, they tried with a different one, of an arrow shape and nearer the wings (to reduce the bending force on the fuselage), and this was named -201. Then they discarded the canard altogether and returned to a T-tail shorter fuselage configuration with engines under the trailing edge of the wing. But at this stage the work for an entirely new configuration had already began in earnest. BTW, the internal model number was changed too, from 733 to 969.

 

[blackkite]

KJ_Lesnic,Skybolt,Caravellarella From Japanese AVIATION JOURNAL magazine in September 1984, full scale mock-up of Boeing 2707 was completed in September 1966 same as the phase ⅡC closing day. According to this book,B2707 had some types they were B2707,B2707-100,B2707-200,B2707-201. Full scale mock-up was may be B2707 or B2707-100,but I don't know the difference between B2707 and B2702-100. Overall length of B2707 was 306ft(93.27m) and B2707-200 was 318ft(96.93m).

 

[flateric]

Domo Arigato Gozaimasu, Blackkite!
This is really a treasure chart. Wish I could read Japanese...interesting if English-language analogue exist.

 

[blackkite]

Flateric I am very glad that you really enjoy this chart. I will try to make english version of this chart but it take little long time. Please wait. Or some one already have this original chart and will post.

 

[Skybolt]

Er, I have, but mine is Boeing's proprietary... Moreover, the Japanese one has been reworked to make it more compact, leaving out some models. The original one is more than a meter long. Let me think about it.

 

[blackkite]

Skybolt I imagined that you sure have it. Blackie

 

[Skybolt]

Yep, the hint to a -201 "betrayed me"...

 

[KJ_Lesnick]

I'm reading the document. In one area it lists the plane's weight as 635,000 lbs. In the others it lists it as around 750,000 lbs?

I would assume the plane's weight would have been 750,000 lbs if I'm not mistaken.

I'm wondering how the hell can the plane end up so heavy as it was so much smaller than the original designs, and it used honeycomb skin and sine-web spar construction which all save a lot of weight off of the design?


Kendra Lensick

 

[blackkite]

KJ_Lesnic Yes I confirm 750,000lb(340,193kg,max taxi weight) for B2707-300 production model in some Japanese magazines. Very heavy.

 

[KJ_Lesnick]

Did Boeing contemplate another swing-wing design between the B2707-200 and the final fixed-wing 2707-300? Because I would almost swear in a book (could be wrong) that I saw a design that at least appeared to have side-mounted intakes like an F-4 or a Tu-22M2 with swing-wings and stuff (I'm not 100% sure though)

Kendra Lesnick
(If I'm wrong, than what AM I remembering?)

 

[Skybolt]

Boeing contemplated more than 150 designs between 2707-201 and -300, using the Model 969-XXX internal numbering. I have only a few, and no-one has side-engines, but it could be. No-one of the "finalists" to the -300 place had side engines, though, and AFAIK no of the early 733-XXX had. BTW, internal designation of 2707-300 was 733-633.

 

[Caravellarella]

Dear Boys and Girls, have any of you ever seen proper technical drawings for the proposed 2707-300 derivatives. I know that Boeing planned to offer an original smaller 2707-300 prototype-sized production variant as a sort of long-range "2707-300SP". There was also an all-six abreast seating version and a high capacity transatlantic all-seven abreast wide bodied version.

I recall reading in an old edition of Jane's that the 2707-300 design facilitated major alterations to fuselage width and length because the fuselage was attached to the top of the wing surface and existing nose and tail-cone/empennage structures could therefore be grafted onto new fuselage cross-sections.

I cannot identify any subsequent model designations to cover such variants; 2707-400? 2707-300B?

Skybolt's attachment shows some of the schemes on pages 10-1 to 10-5......

http://www.emotionreports.com/downloads/pdfs/boeing.pdf

Terry (Caravellarella).

 

[fireflash]

Hi there ,I apologise if this is not the right place to show this but I have just built a model of the 2707-100 as provided by Revell.This particular design has a different tail/ lower fin arrangement than the mock up as dislayed by Boeing and was a further development of the machine. It was made for a special interest group who asked me to build it as a prototype.The markings are custom made as the originals were unusable. I have 12 different models of this aircraft including the smaller Monogram 2707-200 with carnards ( which was slightly longer). Hope this is of use to you

Andy

 

[KJ_Lesnick]

Beautiful!

 

[blackkite]

This model clearly shows the demerit of this configulation. When engines installed to the main wing, some portion of wing root bending moment due to lift is cancelled by the weight of engines.

 

[blackkite]

But when engines installed to the horizontal tail stabilizer, this merit disappeared. And the distance between center of gravity and horizontal stabilizer is shortened and trim drag become large. And longitudinal moment of inertia become large, low speed controlability is poor and card is needed. This is the reason why B2707-200's weight increased.

 

[flateric]

But you must admit it looks damn great=) -300 wasn't so sexy...

 

[blackkite]

Flateric Yes I think B2707-300 is very fascinating same as L2000-7. FAA was wrong.

 

[Skybolt]

The reason for having the engines in a so rearward position was to avoid exhaust impingement of the tail surfaces. Some Boeing designer wanted to go for a T-tail and relocate the engines under the wing, but the chief-aerodynamicist of Boeing opposed due the "deep stall" problem. Naturally, it is very improbable that an SST would ever enter a situation in which a deep stall would occur, and moreover the control-systems was so sophisticated for the time (computer control) that it could have been designed to avoid any occurrence of deep stall altogether . But the "powers that were" decided otherwise, and the VG configuration time-bomb started clicking.

 

[blackkite]

SKybolt I ever saw the picture of very large NASA's wind tunnel test model which had T-tail and engines mounted to VG wing. This shape might be nice candidete for SST. I will check my hard disk. I also understand Boeing's chief aerodymanicist's worry. One of the objective of NASA's model was to research deep stall characteristic of this shape. To install podded engins to the wing was one of the Boeing's great invention same as finite element analysis method for structural analysis. In 1967, I was a junior high school boy, I shocked very much to know that FAA chose B2707-200. In Japan, including very famous aerospace enginnering scientist, we believed that FAA chose L2000 because A-12 already achieved mach 3 supersonic cruise. I could not understand why FAA chose such a complex and risky design. Simple is the best.

 

[KJ_Lesnick]

From what I remember, the reason Lockheed lost had to do (at least partially) with the fact that Boeing used it's political connections to ensure its securing the contract. This may have been revenge for the CX-HLS contract in which Lockheed used it's military connections to land the contract, even though Boeing's design was allegedly considered better by many.

KJ_Lesnick

 

[Skybolt]

Regarding the CX-HLS, the decision point was cost. Lockheed won because they underbid both Boeing and Douglas. Regarding the SST, I'm not convinced that the Boeing win was political. Maybe some considerations were given to a "contract balance" between large contractors, but every insider witness I read insist on solid technical grounds for going Boeing, first of all VG. Problem was that even the technically winning proposal wasn't viable from other points of view. The FAA did an extensive technical justification for the choice, and only one author saw and cited it. It stays put in the FAA archives, I think that any comments on the whys of the choice would have to start from that document. Shall see of this in the future.

 

[KJ_Lesnick]

blackkite

Long time ago, I heard that P&W JTF17A had thermal problem. Normally turbo fan engine is surrounded by rather low temperature fan flow but JTF17A had duct burner and engine is surrouned by high temperature combustion gas and engine temperature became high.

Skybolt

The 2000-7a and b had other problems as well. As far as noise, it didn't met the already untenable DC-8 and 707 standard. Moreover, its payload at 4000 miles sunk to 30.000 lbs due to ever increasing demand for reserve fuel. The double-delta had problems at subsonic speeds and the airlines were upset by the need to remain aloft circling waiting for landing on increasingly congested airports. Moreover, the climb rate was lower than the Boeing's one, so the noise footprint problem got even worse. Finally, and this became apparent at the Phase III evaluation, the 2000-7 was weight-wise at the limit, i.e. it had no more room for weight increases, any of those would have required a complete redesign.

(Emphasis mine)

Since the L-2000-7 was at it's limit, and would require a total re-design to enlarge, do you have any idea of what such a redesigned concept would look like (What kind of wings and engines would be used, etc.)?

Regarding compression lift, they didn't apply it simply because (I am oversemplificating, I must admit) there isn't anything like compression lift in the real world... The lift generated by the shockwave is compensated by additional drag. This was proved in the windtunnel at Langley since 1959, and later confirmed in flight testing of the XB-70.

While the shockwave(s) to produce the compression-lift effects would produce some drag along with the lift produced, it is possible to produce proportionately more pressure (in this case lift) than drag (especially with the use of oblique-waves). There are many hypersonic proposals that were built around this principle, and to to the best of my knowledge, the XB-70 had one of the highest L/D ratios of it's day.

P&W risked of being eliminated because they resisted to rise the inlet temperature above 2000 F.

Couldn't they just use some kind of heat-reflector or thermal protection system (a heat-shield), to keep the heat from getting to the core of the engine, and/or use a little bit of air off of the fan-stages to provide air-cooling for the core?

Regarding the CX-HLS, the decision point was cost. Lockheed won because they underbid both Boeing and Douglas. Regarding the SST, I'm not convinced that the Boeing win was political. Maybe some considerations were given to a "contract balance" between large contractors, but every insider witness I read insist on solid technical grounds for going Boeing, first of all VG. Problem was that even the technically winning proposal wasn't viable from other points of view. The FAA did an extensive technical justification for the choice, and only one author saw and cited it. It stays put in the FAA archives, I think that any comments on the whys of the choice would have to start from that document. Shall see of this in the future.

Thank you for clarifying the Lockheed / Boeing CX-HLS issue.


KJ Lesnick

 

[Skybolt]

Lockheed simply stopped to develop the L-2000 design after losing the competition. When they returned to SSTs, in early '70s, they followed a different route, SCAT-15F arrow wing, on input from NASA.
It is not my opinion, it is NASA Langley's, clearly expressed in the report I posted. I oversimplified, naturally, but what emerged was that from the compression-lift as originally envisaged there wasn't much to gain. Waveriding the shockwave is a different concept, from the little of aerodynamic I pretend to know.
P&W, sure they could, but they decided not, and only very late in the competition they accepted to rise the temperature. It is very difficult to judge after-the-fact so complex technical decision, since you don't know what was known then, and what was the options thought feasible.

 

[KJ_Lesnick]

Skybolt

Lockheed simply stopped to develop the L-2000 design after losing the competition. When they returned to SSTs, in early '70s, they followed a different route, SCAT-15F arrow wing, on input from NASA.

Well, I obviously know that Lockheed gave up after losing ;D.

I was wondering what route the design (L-2000) would have taken had they scaled it up to, say the size of the 2707 or the later HSCT, in either capacity or length with the same design ideology as the L-2000 (high L/D ratio, low-trim-drag etc, good low-speed handling, relative light-weight, simplicity over complexity -- not using variable inlets etc.)?

I know the SCAT-15F and cranked-arrows became a very popular design, but didn't they also suffer serious weight problems?

It is not my opinion, it is NASA Langley's, clearly expressed in the report I posted. I oversimplified, naturally, but what emerged was that from the compression-lift as originally envisaged there wasn't much to gain. Waveriding the shockwave is a different concept, from the little of aerodynamic I pretend to know.

I'm confused. I thought they were all wave-riders, and it didn't matter whether it was a wedge, a cone, or a flared ramp?

P&W, sure they could, but they decided not, and only very late in the competition they accepted to rise the temperature. It is very difficult to judge after-the-fact so complex technical decision, since you don't know what was known then, and what was the options thought feasible.

I guess you're right, most of us see better with 20/20 hind-sight.


Kendra Lensick

 

[Skybolt]

As a pure speculation, probably they'd decided to linearly scale-up the design, ending with something like the early iterations that produced the 2707-300. SCAT-15F: when NASA returned on SSTs with the SCAR program in early '70s the requirements had become even more stringent, and kept tightening with time, being always just ahead of the technological state-of-the-art till the end of '90s in every respect: noise, boom, consumptions, and, newly, emissions, expecially NOx and particulates. And the airplane would have acceptable to the airlines. With those requirements on hand, nobody would have been capable to build a commercially viable SST. Something would have to give (noise, for example), but nothing gave.
No, the phenomenon is apparently similar but not the same. And, BTW, no SST used the compression lift idea. Read the NASA report, it is very interesting. Ditto for the report on the flight test of the XB-70s. Has been recently declassified and is available online (someone posted the URL on the forum some time ago in another thread). The compression lift "theory" was accidentally instrumental in convincing the industry that a Mach 3 commercially viable SST was possible and that Mach 3 performance wasn't limited to military applications.

 

[KJ_Lesnick]

As a pure speculation, probably they'd decided to linearly scale-up the design, ending with something like the early iterations that produced the 2707-300.

I assume they would have went tailless... lower drag supersonic...

No, the phenomenon is apparently similar but not the same. And, BTW, no SST used the compression lift idea.

I'm aware of that


Kendra Lesnick

 

[blackkite]

KJ_Lesnick, Skybolt. How about blended wing body double delta for L2000's redesign same as SR-71 and the Jozef's newest work. Passengers only see the sky but at night flight they see very gorgeous scene. After L2000, LOCKHEED changed their design philosophy for SST from double delta to arrow wing. Arrow wing has very high lift to drug ratio around 10 while B2702-300 is around 7. But low speed performance is poor and must apply active control technology. Please look arrow wing mother model of NASA's beautiful SCAT-15F. I used to read Japanese magazine and found that LH2 fuel SST is feasible. According to LOCKHEED design in 1973, 240 seat,M2.7,range 4200nm LH2 SST's maximun take off weight was 167ton while JP fuel SST's was 340ton. (see my post US SST post 1971) But how do we get LH2 fuel? High temperature gas cooling nuclear reactor or solar panel? Japan already constructed HTGR test reactor which reactor outlet gas temperature is 950 degree centigrade and will be connected H2 generating test plant.

 

[KJ_Lesnick]

That SCAT-15F design shown is absolutely stunning. I'm wondering why they didn't also add a slight forward-delta (a higher sweep up front, inboard) to the design. I'd figure it would add the best of both worlds. Vortex lift, the forward delta would work nicely at high mach and produce lift up front.

BTW: That LH2 SST seemed pretty damn impressive. Too bad it never got the go-ahead. It might have been completely clean in regards to NOx emissions

 

[Sundog]

Vortex lift, the forward delta would work nicely at high mach and produce lift up front.

1) Vortex lift is at low speeds and high alpha and practically every delta develops it. However, Vortex Flaps would help as well, but they weren't around then, to the best of my knowledge.

2) I'm sure the A.C. is right where Lockheed wanted it, so there would be no need to add to it further up. It's a transport design, not a high alpha fighter. As such, the wing shape is already optimized for cruise.

 

[KJ_Lesnick]

Sundog

1) Vortex lift is at low speeds and high alpha and practically every delta develops it. However, Vortex Flaps would help as well, but they weren't around then, to the best of my knowledge.

That is correct. However having a very highly swept surface to generate a very powerful vortex which is then used to augment the vortices produced by the rest of the wing (double-delta) is more effective than just using a standard delta.

2) I'm sure the A.C. is right where Lockheed wanted it, so there would be no need to add to it further up. It's a transport design, not a high alpha fighter. As such, the wing shape is already optimized for cruise.

The Center of Pressure shifts rearward when you go supersonic. If it's too much, trim-drag goes up. I know the L-2000 got around that problem by having the forward-delta highly-swept and cambered, combined with a twisted rearward-delta which produced disproportionate amounts of lift up front so as the center of lift went back over the rest of the wing, this negated it (trans-sonically trim-deflections were moderate, as you went faster though the deflections progressively dropped as you reached cruise) allowing reasonably low trim-drag.

While this wing has a great deal of twist to it (which may have been used to negate the shift in the C/L), higher leading-edge sweeps allow for the shock-wave to be kept more easily behind the wing's LE, and allow greater use of conical-camber (which is better for both high and low-speed), and higher-sweeps also produce lower-drag.


Kendra Lesnick

 

[Sundog]

The Center of Pressure shifts rearward when you go supersonic. If it's too much, trim-drag goes up. I know the L-2000 got around that problem by having the forward-delta highly-swept and cambered, combined with a twisted rearward-delta which produced disproportionate amounts of lift up front so as the center of lift went back over the rest of the wing, this negated it (trans-sonically trim-deflections were moderate, as you went faster though the deflections progressively dropped as you reached cruise) allowing reasonably low trim-drag.

While this wing has a great deal of twist to it (which may have been used to negate the shift in the C/L), higher leading-edge sweeps allow for the shock-wave to be kept more easily behind the wing's LE, and allow greater use of conical-camber (which is better for both high and low-speed), and higher-sweeps also produce lower-drag.

I saw the numbers for this design when I was back in school in the eighties, it's design was fine just as it is. It turns out Lockheed actually knows what it's doing when it comes to designing aircraft.

The twisting on the wing (L2000) isn't about "disproportinate lift" it's about minimizing cruise drag. Granted, that includes minimizing trim drag as well, but it's also about keeping the flow laminar as much as possible in a conical flow field; which isn't necessarily better at low speeds, especially considering it's an off-design point.

 

[Skybolt]

During the '70s the focus of SST designs migrated from L/D to emissions and noise (both low speed and boom). And since then things have only become more focused on those.

 

[KJ_Lesnick]

Sundog

I saw the numbers for this design when I was back in school in the eighties, it's design was fine just as it is. It turns out Lockheed actually knows what it's doing when it comes to designing aircraft.

What was the L/D ratio anyway at supersonic speed anyway? Over 8.0 to 1?

Of course, I know Lockheed is an excellent aircraft designer. They have made mistakes in the past though and are not perfect.

The twisting on the wing (L2000) isn't about "disproportinate lift" it's about minimizing cruise drag. Granted, that includes minimizing trim drag as well, but it's also about keeping the flow laminar as much as possible in a conical flow field; which isn't necessarily better at low speeds, especially considering it's an off-design point.

Well, as a rule of thumb, to minimize trim-drag aerodynamically (which Lockheed preferred) the wing has to either just naturally have a very low shift in the center of pressure, such as a highly-swept wing (or a swing-wing with it's wings all the way back), or the wing has to have means to produce extra lift up front to compensate (ie. a canard, or design the wing in such that it would produce lift at the forward most area of the wing in large amounts whilst supersonic ideally so at cruise the trim-drag levels are low enough to keep the elevon deflections minimum or flush -- a chine/strake as on the exemplifies this).

Laminar flow if possible is an excellent way to reduce drag overall, though, and I suppose the flow being less turbulent would improve the effects of the control-surfaces, requiring lower deflections for the same results.


Skybolt

During the '70s the focus of SST designs migrated from L/D to emissions and noise (both low speed and boom). And since then things have only become more focused on those.

Truthfully, even during the SST program (1963-1971) effort was made to reduce sonic boom (they just weren't very good at it), but I'd have to say that modern supersonic-airliner designs do seem to be far more focused on pollution, sonic-boom, and noise reduction, than L/D ratio.

And while I understand the need to reduce NOx emission, and I could understand the desire to reduce noise over the SST-design and the Concorde levels, (although I think current FAA regs are a bit over the top) but the plane's gotta fly good first!


Kendra Lesnick

 

[Skybolt]

Kendra, in a aircraft enthusiast world, first you fly a project for the sheer beauty of it, then you decide if it is economically or something-else-y worthwhile... we are not in an aircraft enthusiast world, I fear and regret...
Emissions: in a few months, NOx was only part of the problem, were risen fears for particulate, and water vapour and what-ever. As has been recently written, the SST, being economically weak for the airlines, was (is) an easy game for those who want(ed) to flex their PR muscles in shooting down some "big technology" project. As an OT rant, did someone notice in New Scientist a couple of weeks ago the lamentations on the fact that one US Federal Agency has blocked for at least two years a gigantic private project of turning a large expanse of South-Western desert (actually, steppe) in a solar power field on account of endangering the ambient of a desert tortoise ? New Scientist went just a shy from a "Damn the tortoise, full speed ahead"... Contrappasso, so said Dante in the "Divine Comedy"...

 

[KJ_Lesnick]

Kendra, in a aircraft enthusiast world, first you fly a project for the sheer beauty of it, then you decide if it is economically or something-else-y worthwhile... we are not in an aircraft enthusiast world, I fear and regret...
Emissions: in a few months, NOx was only part of the problem, were risen fears for particulate, and water vapour and what-ever. As has been recently written, the SST, being economically weak for the airlines, was (is) an easy game for those who want(ed) to flex their PR muscles in shooting down some "big technology" project. As an OT rant, did someone notice in New Scientist a couple of weeks ago the lamentations on the fact that one US Federal Agency has blocked for at least two years a gigantic private project of turning a large expanse of South-Western desert (actually, steppe) in a solar power field on account of endangering the ambient of a desert tortoise ? New Scientist went just a shy from a "Damn the tortoise, full speed ahead"... Contrappasso, so said Dante in the "Divine Comedy"...

Skybolt... I guess you're right, aircraft building just for the sake of aircraft building, just like doing anything just for the sake of doing is not a good idea.

However, I do not recall spefically saying that I objected to reducing NOx levels (Destroying the ozone layer exposing everybody to large amounts of UV just ain't cool, and while I got a nice tan and have never got a sunburn, even black people can get skin cancer...) -- I just simply said that the plane has to be able to fly well in addition to any other requirement entered into the equation.


KJ_Lesnick