GE4 Turbojet (Boeing 2207 SST)

What portions or components of the J93 went into the GE4? For the longest time I think the GE4 held the record for jet engine thrust until the modern high-bypass ration turbofans came along.
 
GE4/J5P
Type: Single-shaft axial turbojet with afterburner.

Intake: Annular, comprising front structural frame with eight radial struts supporting compressor front bearing housing.

Compressor: Nine-stage axial single-shaft unit with variable incidence inlet guide vanes and stator vanes, giving large stall margin for inlet distortion tolerance. Front and rear groups of stators are individually actuated for starting airflow control and for high airflow capability at supersonic speeds. Rotor construction is combined drum-and-disc with thin-section centreless discs. No 1 disc is overhung on forward conical extension shaft supported by compressor front roller bearing. Rearward conical extension shaft attached to periphery of No 9 disc is supported by centre main ball thrust bearing. Thin-section air tube located on front and rear conical shafts, passes through disc centres. Compressor delivery diffuser is integral with mid-section structural frame supporting centre main bearing. All stator vanes carried on inner and outer swivel bearings, with inner support rings sealing against rotor inter-disc drums. For reduced weight, rotor blades in stages 1 to 4 are hollow diffusion-bonded titanium alloy, and stage 5 to 9 electro-chemically drilled superalloy. Pressure ratio 12-5:1, mass flow 633 lb/sec (287 kg/sec).

Combustor: Fully annular design of moderately high heat release rate with primary air annulus having multiple axial swirl cups.

Turbine: Two-stage axial unit with air-cooled cast alloy nozzle guide vanes and rotor blades. Thin-section centreless discs with arched inter-stage spacers. Rotor blades have dovetail root fittings and second stage blades are tip-shrouded. Forward conical extension shaft attached to periphery of stage 1 disc locates with compressor rear conical shaft at centre main ball thrust bearing. Rearward tubular shaft extension from stage 2 disc located in rear main roller bearing. Stage 2 nozzle guide vanes cantilever mounted from outer end, with seal onto interdisc spacer at inner end.

Exhaust System: Annular exhaust duct from turbine with rear structural frame, with radial/tangential struts, supporting curved centre cone and turbine rear bearing. Turbine entry temperature at T-O, in excess of 2,000°F (1,366°K).

Afterburner: Conventional system with four V-gutter flame stabilisers mounted on radial struts in exhaust duct. Two-stage fuel injection enables thrust modulation over full augmentor temperature range. Annular thermal shield protects duct wall between combustion zone and variable nozzle. Fuel supply manifold encased in external annulus around exhaust duct.

Exhaust Nozzle and Thrust Reverser: Two-stage nozzle with integral thrust reverser. Comprises variable area primary nozzle positioned by hydraulic actuators which also "overtravel" to act as reverser blocker. Long-section secondary shroud includes tertiary air inlet doors which open for low speed operation and can be selectively locked open for reverser operation. Secondary nozzle provides guided expansion of exhaust gases and is pressure-positioned for optimum area ratio. For reverse thrust, primary nozzle translates rearwards to expose thrust reverser ducts (tertiary air inlet doors), closing to form a block, thus directing gases forward through the ducts. Provision also for noise suppression.

Fuel Systems: Hydromechanical primary engine and afterburner fuel control systems.

Accessories: All engine controls and accessories housed in sealed compartment under front of engine cooled by normal circulation of fuel to protect from high temperature environment at supersonic cruise. Accessory drive is via bevel gear box in nose cone, driven-ofF front of compressor. Drive shafts for accessories and airframe purposes pass through front frame radial struts.

Dimensions:
Max diameter (over exhaust nozzle) 89.5 in (2,280 mm)
Length overall 308 in (7,823 mm)
Weight, dry: (Dependent on specific installational features) 11,300 lb (5,100 kg)
Performance Ratings: Max augmented T-O
67,000 lb (30, 390kg) st at 5,200 rpm Max augmented T-O
50,500 lb (22,900 kg) st at 5,200 rpm Max flight conditions
Mach 2.7 at 82,000 ft (24,994 m)
Cruise at Mach 2.7 and 65,000 ft (19,812 m) 15,000 lb (6,804 kg)
Specific Fuel Consumption:
At cruise rating 1.50 lb/lb/hr (1.50 kg/kg/hr)
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Flying Review International, Dec 1969
 
Just a question : was this engine tested ? This would mean that something of the american SST existed for REAL...
 
This engine saw lots of ground testing but was never, to the best of my knowledge, flight tested. I'm really not certain how they could have flight tested it in the supersonic region, anyway. The flight tests of the J93 utilized a pod that just barely fit under the B-58 carrying it and the GE4 was a larger engine.
 
I seem to recall that at one stage the XB70 was proposed as a possible supersonic tesbed for this engine.

I think there is reference to this in the excellent Tony Landis book on the XB70, I think the idea was to replace several of the YJ93's on one side with a single GE4?

One thing I do find extraordinary about this engine is that it appears to have disappeared without a trace, I find it hard to believe that such a powerful engine simply found no application whatsoever!

A few years ago there were some allegations on the FAS website regarding the alleged "Brilliant Buzzard" project where it was speculated that the powerplant could well have been the GE4.

While on the subject of SST powerplants, does anyone have any info whatsoever on P&W's loser to the GE4?
 
Maybe using a concorde as testbed ? ::)
I'm asking if it would have been possible fitting the enigne on a B-58, not on the J-93 pod but maybe on a wing pylon (deleting the two J-79 on the same side). Something dangerous to fly, that's sure!
 
Overkiller said:
While on the subject of SST powerplants, does anyone have any info whatsoever on P&W's loser to the GE4?
Click to expand...

Pratt & Whitney's engine was the JFT20, an afterburning two-spool turbofan that shared technology with the JFT22 (F100/F401) that developed from the experimental JTF16 engine. When the SST mockup was in a museum in Kissimee, Florida, they had a JTF20 engine there on loan from P&W.
 
Couple of pics from the test stand.
 

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elmayerle said:
This engine saw lots of ground testing but was never, to the best of my knowledge, flight tested. I'm really not certain how they could have flight tested it in the supersonic region, anyway. The flight tests of the J93 utilized a pod that just barely fit under the B-58 carrying it and the GE4 was a larger engine.
Click to expand...

Though the B-58 did get the pod fitted and pictures where captured , it never was fired up, never tested with the B-58
 
Overkiller said:
While on the subject of SST powerplants, does anyone have any info whatsoever on P&W's loser to the GE4?
Click to expand...

The JTF-17A -- it was a twin-spool, low-bypass duct-burning turbofan (bypass ratio: 1.3 to 1). It's dry thrust output seemed to point to figures around 39,000 lbf (I have heard claims of figures as high as 53,000 lbf dry, but any reliable sources about the SST program do not indicate these figures indicating that, most likely, the 53,000 lbf figure is not reliable or accurate) with afterburning thrust on the order of 61,000 lbf. The engine had no inlet guide-vane, and from what I remember had a 3-stage fan, a 6-stage HP compressor, and an annular combustion chamber.


elmayerle said:
Pratt & Whitney's engine was the JFT20, an afterburning two-spool turbofan that shared technology with the JFT22 (F100/F401) that developed from the experimental JTF16 engine. When the SST mockup was in a museum in Kissimee, Florida, they had a JTF20 engine there on loan from P&W.
Click to expand...

Pratt and Whitney's contender was the JTF-17A -- I have never heard of the JTF-20 being used for P&W competitor to the GE-4?


Kendra Lesnick
 
Another one.
 

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Sentinel Chicken,

I can tell you the air-cooling scheme seems to have been incorporated, the hollow-turbine blades with holes drilled in the back of the first (turbine) stage as well, as well as variable-guide-vanes. The engine also has an annular combustion-chamber like the J-93.

It also has characteristics from the GE-1 (which I actually know very little about, other than it had 14-stages, which I read in one of Bill Gunston's engine books) as well.


Kendra Lesnick
 
overscan,

I found a STINET link which sheds some light on the nozzle-design and sound-suppression technology to be incorporated into it's configuration
URL: http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD=AD907109
 
Overkiller said:
I seem to recall that at one stage the XB70 was proposed as a possible supersonic tesbed for this engine.

I think there is reference to this in the excellent Tony Landis book on the XB70, I think the idea was to replace several of the YJ93's on one side with a single GE4?

One thing I do find extraordinary about this engine is that it appears to have disappeared without a trace, I find it hard to believe that such a powerful engine simply found no application whatsoever!

A few years ago there were some allegations on the FAS website regarding the alleged "Brilliant Buzzard" project where it was speculated that the powerplant could well have been the GE4.

While on the subject of SST powerplants, does anyone have any info whatsoever on P&W's loser to the GE4?
Click to expand...

Four years later... ;)

B-52 projected testbed for GE4
books.google.fr

Aviation Week & Space Technology

A February or March issue is called Annual inventory of aerospace power (title varies slightly).
books.google.fr

XB-70 testbed for GE4
books.google.fr

XB-70 Valkyrie

Though production of the XB-70 Valkyrie was limited to just two prototypes, it remains one of the most incredible aircraft ever built. Conceived at the height of the Cold War, the XB-70 was envisioned as long-range, high-altitude bomber capable of Mach 3 at a time when fighter aircraft one-tenth...
books.google.fr

No in flight test bed for GE4
books.google.fr

Aviation Week & Space Technology

A February or March issue is called Annual inventory of aerospace power (title varies slightly).
books.google.fr

google books is quite useful :)
 
I believe the National Air and Space museum had one in their storage facility at Garber. Maybe we'll see it one day when they move everything to the new hangar at Udvar-Hazy.
 
AeroFranz said:
I believe the National Air and Space museum had one in their storage facility at Garber. Maybe we'll see it one day when they move everything to the new hangar at Udvar-Hazy.
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They did...and I think it's now on display.
 
This is a re-post from within a seperate SST thread we have on U.S. SST's. I'm not sure if you want a seperate thread for the PW engine, since you also have this thread listed as Boeing 2707 SST.

GE 2707 Airframe Engine Technical Agreement

PW 2707 Airframe Engine Technical Agreement

The GE pdf is a bit tough to read, because all of the text is double imaged. Maybe someone here knows of a clean copy. There looks to be some good engine data in these. I've been doing some research, trying to find some engine decks or the most jet engine data I can find. I'm not sure this goes here. If we start digging into this more, maybe we should have a separate section for propulsion?

Anyway, enjoy.
 
Sundog said:
This is a re-post from within a seperate SST thread we have on U.S. SST's. I'm not sure if you want a seperate thread for the PW engine, since you also have this thread listed as Boeing 2707 SST.
Click to expand...

Probably a very good idea Sundog; the existing SST topic is disparate, nonsensical and confusing beyond belief......

Terry (Caravellarella)
 
I just stumbled upon it on youtube one day. Thought for sure I'd posted it before here. ???
 
Aeroengineer1 said:
I can confirm that this engine still exists. It was not scrapped out. It is a massive engine.
Click to expand...

That's an understatement. :) The XB-70's J93 already was a monster, but the GE4... was a much scaled-up variant.
And its 70 000 pounds of afterburning thrust was merely a beginning.
Look at this page: short list of variants.

75 000 pounds of thrust with the afterburner removed... geez. GE4s could have lifted cathedrals out of Earth solid ground.

Turbojet with afterburner:
GE4 Block 1: Hinged primary nozzle and cascade thrust reverser,
GE4/J5 Block 2: Hinged primary nozzle and cascade TR,
GE4/J5P Prototype: Leaf-type primary nozzle and blocker door TR.
GE4/J6G Production Design: Leaf-type primary nozzle and blocker door TR.
The thrust reverser of the latter 2 used the variable segments of the primary nozzle as reverser blockers.
Click to expand...
The above variants had lost favor due to noise considerations shortly before B2707-300 project cancellation. There were 2 more development proposals:

Turbojet without afterburner:
GE4/J6H Tentative Design: Favored by program directors, greater simplicity and the need for less new design and development work.

Turbofan with limited afterburner for acceleration to cruise speed:
GE4/J7A Tentative design: "Leaky fan" with a bypass ratio of 0.3.
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GE4/J6G: 70,000 lb. (turbojet with AB)
GE4/J6H: 75,000 lb.* (dry turbojet)
GE4/J7A: 75,000 lb.* (turbofan)
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* The 2 tentative designs need some further explanation:
Both tentative designs were intended to produce the same maximum 108 perceived noise in decibles (epndb.) in takeoff sideline noise as called for in FAR 36 for new subsonic jet aircraft of that era.

A suppressor would be used with both engines, and improvements in these as well as low-speed lift improvements to the aircraft design helped to reach the 108 epndb. level.

To produce the noise reduction from the 124 epndb. level anticipated in the earlier prototype/production designs, both engines would be used on takeoff at less than full thrust. Thus, according to preliminary projections at the time, each engine would take off using about 55,000 lb. of thrust of the 75,000 lb. available for a 298 passenger aircraft.

Key to the quieter engine performance was the much greater airflow expected from both of the 2 new engines. Tentative engine data indicated a maximum takeoff airflow of 815 lb./sec. This was greater than optimum in order to reduce noise. The turbojet/afterburning prototype engine GE4/J5P, by contrast had a takeoff airflow of 633 lb./sec.

Accompanying the increased airflow, as part of the noise reduction measures, was a decrease in exhaust velocity from 3,500 ft./sec. in the prototype with full afterburner on takeoff to a range of 2,000-2,500 ft./sec. for the tentative new designs. For both the proposed fan and dry turbojet engines, the first stage compressor inlet diameter would be increased from 60.6 to 68.7 in.

Among the additional complications produced by going to a fan engine would be substitution of a 2-spool design for a single-spool planned for the dry turbojet. Both would rely as much as possible on then existing GE4 technology with changes in the combustor and turbine sections primarily only in dimensions.

Part of the takeoff noise reduction would come from a lower power setting (55,000 lb. per engine instead of the previously planned 63,000 lb.). Part of this reduction was possible through better takeoff and climb lift characteristics from the wing than anticipated, but another factor was that the hot-day FAR balanced field length requirement at maximum takeoff weight was to be extended from 10,200 to 12,400 ft.
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Opportunistic Minnow said:
Apologies if already posted elsewhere but some interesting GE4 details here:

archive.org

NASA Technical Reports Server (NTRS) 19770011052: Proceedings of the SCAR Conference, Part 1 : NASA Technical Reports Server (NTRS) : Free Download, Borrow, and Streaming : Internet Archive

The Supersonic Cruise Aircraft Research (SCAR) team analyzed six major topics: (1) aerodynamics, (2) stability and control, (3) propulsion, (4) environmental...
archive.org
Click to expand...
I haven’t seen those NASA reports posted in the Propulsion forum before. Great reading on the work being done in the early to mid 70s
 
Opportunistic Minnow said:
Apologies if already posted elsewhere but some interesting GE4 details here:

archive.org

NASA Technical Reports Server (NTRS) 19770011052: Proceedings of the SCAR Conference, Part 1 : NASA Technical Reports Server (NTRS) : Free Download, Borrow, and Streaming : Internet Archive

The Supersonic Cruise Aircraft Research (SCAR) team analyzed six major topics: (1) aerodynamics, (2) stability and control, (3) propulsion, (4) environmental...
archive.org
Click to expand...
Thanks for posting!
BTW I am slowly restoring a copy of the J93/GE3 assembly repair manual, father of the GE 4.
 
RareBird said:
Opportunistic Minnow said:
Apologies if already posted elsewhere but some interesting GE4 details here:

archive.org

NASA Technical Reports Server (NTRS) 19770011052: Proceedings of the SCAR Conference, Part 1 : NASA Technical Reports Server (NTRS) : Free Download, Borrow, and Streaming : Internet Archive

The Supersonic Cruise Aircraft Research (SCAR) team analyzed six major topics: (1) aerodynamics, (2) stability and control, (3) propulsion, (4) environmental...
archive.org
Click to expand...
Thanks for posting!
BTW I am slowly restoring a copy of the J93/GE3 assembly repair manual, father of the GE 4.
Click to expand...
My pleasure. Sounds intriguing!
 
One interesting feature of both the YJ93 and GE4 is the use of variable compressor vane at both the front section and rear section of the compressor, mentioned in the engine description early in this thread.

Most engine with variable vanes have them in the front block of the compressor. The geometric narrowing of the compression path is set to match the pressure ratio across the compressor at the design rotor operating point at full power. At slow rotor speeds with a lower pressure ratio, the geometric narrowing result in the airflow having to speed up thru the compressor, reaching Mach 1 and choking the flow in the back end. This results in the air slowing down at the front end, increasing the angle of attack and stalling the front end of the compressor. Starting and low power operation can be greatly impacted in these conditions. Solutions are to open a mid compressor bleed to dump the extra air from the front end of the compressor, variable vanes to reduce the compressor blade angle of attack to reduce flow (essentially making the front on the compressor smaller), or both.

Under high Mach conditions, the inlet air to the compressor becomes very hot. At a constant mechanical rotor speed, the effective (I.e. corrected rotor speed) decreases with the square root of the absolute temperature ratio. This moves the compressor operating point back towards low power operation, reducing the effective thrust of the engine and pushing it towards the front end stall conditions.

The J58 engine in the SR-71 dealt with this issue with variable inlet guide vanes and compressor bleed. The genius addition of the bleed bypass tubes to route the bleed back to the afterburner made sure this bleed air was not wasted and contributed to the thrust of the engine at M3+ conditions.

The GE solution was the variable vanes in the back of the compressor. While the variable vanes in the front made that part of the compressor smaller, the vanes in the back of the compressor opened, effectively making the back end bigger, so all of the air flowed thru the combustor and turbine.

Different ways to address the same high inlet temp compressor conditions, don’t know which was more effective in generating thrust at their respective cruise conditions.
 
Archibald said:
B-52 projected testbed for GE4
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Source:
AVIATION WEEK
SEPTEMBER 12, 1966
-SHORTLINES - AIRLINE OBSERVER -
PAGE: 51
"General Electric Co. will use a B-52 obtained from USAF as a test bed for its GE4 turbojet engine for the U.S. supersonic transport.
The engine will be mounted on the No. 3 pylon in place of the B-52's twin-engine nacelle."
 
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