Pratt & Whitney J58 (JT11D-20)

sferrin

sferrin

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Does anybody know if this article was ever completed?

J-58 page pdf

aerostories, des avions et des hommes.<br>aerostories, planes and people.
aerostories.free.fr

Looks like parts 2&3 are missing from the English version and part 3 doesn't appear to be available in French either.
 
A significant portion of the SR-71's J-58 engine thrust was provided by turbine bypass air that was dumped into the afterburner. (See diagram.) Question: Could the same principle be used with a non-afterburning turbofan or turbojet engine? The idea would be to take excess intake air and channel it into the non-afterburning exhaust stream. The intended effect would be to increase the mass of the exhaust, thereby increasing thrust. Please be kind. I am not an engineer.

Bronc
 

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sferrin said:
That's how non-afterburning turbofans work. ;)
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Well, I'm talking about air that doesn't pass through the turbofan at all. I'm talking about excess intake air that bypasses the engine completely and is channeled into the exhaust. It would be a "double bypass" engine. The J-58 worked like a ramjet in this way, but I'm just talking about high-speed intake air that is channeled all the way back and dumped into the exhaust.

Bronc
 
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Broncazonk said:
Well, I'm talking about air that doesn't pass through the turbofan at all. I'm talking about excess intake air that bypasses the engine completely and is channeled into the exhaust. It would be a "double bypass" engine. The J-58 worked like a ramjet in this way, but I'm just talking about high-speed intake air that is channelled all the way back and dumped into the exhaust.
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The afterburner, the spike and the velocity of the aircraft are crucial to generating thrust. In effect the J58 acts as a ramjet at high speeds with little air going through the turbine: air is compressed by the intake shape and its velocity and then accelerated via heating in the afterburner stage.

The bypass air of a turbo fan provides thrust because it has been accelerated by the mechanical effect of the fan like a propeller. If you are bypassing air outside the engine all together it may provide some jet effect if it has been compressed by the intake but it’s very unlikely to be higher than the drag caused by the additional size of the intake. So it won’t be generating any thrust.
 
Abraham Gubler said:
If you are bypassing air outside the engine all together it may provide some jet effect if it has been compressed by the intake but it’s very unlikely to be higher than the drag caused by the additional size of the intake. So it won’t be generating any thrust.
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IIRC they did something like this on the XF8U-3 but it had an ejector that that air got dumped into along with the engine exhaust.
 
sferrin said:
IIRC they did something like this on the XF8U-3 but it had an ejector that that air got dumped into along with the engine exhaust.
Click to expand...

Well, something was going on, because the Crusader III was an ass-kicker all the way around, it was ugly, but an ass kicker in every direction.

@LowObservable: Thank you for that link, very interesting reading. I love reading recollections like that.

Bronc
 
Broncazonk said:
sferrin said:
IIRC they did something like this on the XF8U-3 but it had an ejector that that air got dumped into along with the engine exhaust.
Click to expand...

Well, something was going on, because the Crusader III was an ass-kicker all the way around, it was ugly, but an ass kicker in every direction.

@LowObservable: Thank you for that link, very interesting reading. I love reading recollections like that.

Bronc
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Interesting tidbit about the Crusader III: In Tommy Thomason's excellent tome on the a/c, the subject of the oft heard claim that the ship would actually have done Mach 3 notes that that assumed a different engine in the bird--the J58.
 
F-14D said:
Broncazonk said:
sferrin said:
IIRC they did something like this on the XF8U-3 but it had an ejector that that air got dumped into along with the engine exhaust.
Click to expand...

Well, something was going on, because the Crusader III was an ass-kicker all the way around, it was ugly, but an ass kicker in every direction.

@LowObservable: Thank you for that link, very interesting reading. I love reading recollections like that.

Bronc
Click to expand...

Interesting tidbit about the Crusader III: In Tommy Thomason's excellent tome on the a/c, the subject of the oft heard claim that the ship would actually have done Mach 3 notes that that assumed a different engine in the bird--the J58.
Click to expand...

Yeah, but even with the right version of the J75 it would still haul ass. (That's a great book BTW.)
 
If excess intake / inlet air could be ducted all the way back and dumped into the exhaust stream in the manner of the pdf... The only difference is the location of the intake.

Bronc
 
Broncazonk said:
If excess intake / inlet air could be ducted all the way back and dumped into the exhaust stream in the manner of the pdf... The only difference is the location of the intake.

Bronc
Click to expand...
There is no "excess" intake/inlet air for most engines.
 
How hot are the exposed metal parts of the engines on the T-50? I'm thinking that the planned for, but not yet attached, T-50 ducting (pictured) have two purposes: to reduce the IR signature of the exhaust and to increase the mass / thrust of the exhaust. I was thinking along similar lines, but by bringing intake air all the way back around both engines to do it. (I don't know much about this stuff, I just like to think about it a lot.)

Bronc
 

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To clear up some aerostories designations , eg incorrect J58-P-4 for A-12, the 3 designations for applications for this engine according to Jack Connors "The Engines of P&W":

J58-P-2 proposed Navy fighter
JT11D-20 A-12, SR-71
J58-P-4 A3J cancelled 1962
 
According to Skunkworks:
Gusto, Oxcart and Archangel were the three aircraft configurations that developed into the A-12; P&W were involved from the start and it was intended that the J58 would be used...this had been sponsored originally by the Navy as a conventional, but very advanced, turbojet engine providing extraordinarily high thrust with the ability to operate at speeds up to Mach 3. By the time the A-12 came along the J-58 had become increasingly difficult and expensive to develop. Also several of the aircraft for which the engine was intended , including the F8U-3 had ceased to exist. By 1959 the engine was an orphan!
On Jan 30 1060 Lockheed received official funding for 12 A-12 and P&W received the go-ahead to build 3 test bed engines and 3 for the first flights in early '61.
As originally conceived the engine was to use conventional ram compression at supersonic speeds to augment the compressor's moderate compression ratio. With its conventional afterburner and con-di nozzle the J58 was intended to have a thrust of up to 45,000 lb static sea level.
The more radical approach to the A-12's Mach 3 cruising speed led to a major redesign of the J58. The new configuration had air bypassed from the fourth-stage of the h-p compressor section and dumped into the afterburner duct creating a highly efficient ramjet effect augmenting hte thrust generated by conventional means.
The engine and aircraft build programmes slipped by more than a year as problems revealed themselves ... how obtain titanium of sufficient quality and then shape it into an aircraft; how to make the engine behave!
Lockheed made the decision to use the J75 engine for the first flights and doing everything possible to raise take-off thrust...water injection, higher TET and rpm. Even this engine needed compressor disc redesign before it was suitable for the A-12 first flights; the second A-12 to fly was a trainer version with J75s;the third had one J58 and one J75! The J58 was down on thrust up on sfc the control was erratic with thrust jumps occurring for no reason... also it had difficulty performing above 75,000 ft. Another year of development and CIA funds put this right!
Peter Law of AEHS has written on this engine ..here are some snippets attached.
 

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Jack Connors "The Engines of P&W"... ref the Navy J58 redesign for the CIA A-12 spy plane.

Quote by Jack McDermott, J58 Program Manager
"It was neither an Air Force nor Navy engine and to disguise the customer we gave it the company designation JT11-20. However most people called it the J58."

Note: Air Force engines odd J's eg J47 Sabre, J57 Voodoo
Navy evens eg J52 Skyhawk

and the inevitable exceptions eg J57 Skywarrior, Crusader
 
From Skunkworks...
and dumped into the afterburner duct creating a highly efficient ramjet effect augmenting hte thrust generated by conventional means.
Click to expand...

The J58, a much-misunderstood engine, as shown by both both assertions in above quote being incorrect.

The true uniqueness in the way this engine operated is only to be found in statements in the definitive paper on the propulsion system, see below, and in Peter Law's presentation fig17 which shows a gas generator epr at cruise of less than one (0.9).

http://arc.aiaa.org/doi/abs/10.2514/3.60402 "F-12 Series Aircraft Propulsion System Performance and Development" by David Campbell.
"My sidekick in propulsion, David Campbell, a brilliant aerotherodynamicist, who dropped dead from a massive coronary at only twent-six" Quote from Ben Rich in his book "Skunk Works".
 
This was the period when the Iroquois was being sorted and the Gyron was being developed. The technologies developed by the J58 were to have a major impact on the future development of the GT, only 20 odd years after the first flight demos of the invention... that is pushing capabilities of the development teams to the limit.. nobody had done this before so there were no real clues to help. The people that followed could ask "how do I apply that piece of knowledge to my particular challenge?" The J58 team were asking what knowledge do I have to generate in order to solve this particular challenge?".... a much more stressful undertaking, and more exciting.
 
charleybarley said:
Jack Connors "The Engines of P&W"... ref the Navy J58 redesign for the CIA A-12 spy plane.

Quote by Jack McDermott, J58 Program Manager
"It was neither an Air Force nor Navy engine and to disguise the customer we gave it the company designation JT11-20. However most people called it the J58."

Note: Air Force engines odd J's eg J47 Sabre, J57 Voodoo
Navy evens eg J52 Skyhawk

and the inevitable exceptions eg J57 Skywarrior, Crusader
Click to expand...

The difference between odd and even engine designations was done in order to somewhat delink the coordination required of the Air Force and Navy. However, this was in no way (or at least only in a limited way if the production supply did not meet the demand, which may be why the F3H-2 was saddled with the J71) an impediment to one service using an engine developed by the other. A dash number was used to designate an engine configuration for a specific aircraft or a spec change. These dash numbers also followed the odd and even protocol. For example, the J57 for the F-100A was either the J57-P-7 or -39; the J57 for the F8U-1 was the J57-P-4 and the non-afterburning J57 for the A3D was the -6.

In researching the J58 for my F8U-3 monograph, it was difficult to nail down the configuration, even a picture, of the -2 engine proposed for that airplane or the A3J (it's not clear to me that the A3J engine was a -4, although that seems logical if in fact an engine for that installation was defined by a military specification; up until that point, an engine was often referred to by its manufacturer's designation). Most of what is available on the J58 concerned the one designed for the Lockheed A-12, which was a major redesign, aka the P&W JT11D-20A/B, possibly designated the -4. From the previously cited http://aerostories.free.fr/technique/J58/J58_01/page9.html
 

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Cool story about the development of the A-12 engine here:


Never Told Tales of Pratt & Whitney by Dr. Bob Abernethy

Photos, stories, death obituaries, biographies recording legacy of CIA, Air Force, Army men and women work secret atomic, radar, satellite flights in the Nevada desert, Kadena, Okinawa, North Korea, Vietnam
roadrunnersinternationale.com roadrunnersinternationale.com


The patent still calls it the Recover Bleed Air turbojet. By the time Bob Abernethy's boss realized that the wily engineer had filed a patent that gave the engine his own initials, it was too late.


 

The heart of the SR-71 : the J-58 engine. Development

aerostories, des avions et des hommes.<br>aerostories, planes and people.
aerostories.free.fr

Does anyone know where this site obtained some of its more surprising information? I don't mean the sources we all know about ( eg AEHS, manuals, patent, Never told tales, Roadrunners, etc) but more particularly stuff like the altitude stand capability diagram in section 1.3?
 
He is a well known (in France) expert aeronautical author of books like the Putnam books in this country... I guess he has had access to Lockheed and P&W archives or has contact with some of the personnel.... or he has these DVDs!!!
 
Vahe Demirjian said:
I'm not sure why parts 2 and 3 weren't uploaded in English, but it is best to remove this thread from "Postwar Aircraft Projects" because it deals with a jet engine rather than an unbuilt aircraft project.
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I suppose they were originally written in French ( Phillipe Ricco is a French aviation writer),
and only part one was translated.
 
Thank you.
It may be 'basic' to the regulars, but I learned a lot.
 
Pratt & Whitney, From Secret Project Suntan To The J58 That Powered The Blackbird, To Space
 
J-58 photos I took a few years back at Pima Air Museum (Arizona) and March Air Museum (California). The March photos include a rear shot of an installed J-58 in their SR-71. The engine bypass pipes from the compressor stage can seen closeup in a couple of the photos. The compressor face (covered in clear plastic is also shown.
 

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Pratt & Whitney PART 2, From The F100 To The F119 That Powers The F-22 Raptor.
 
This is quite a treasure trove of information, though some links appear to have been lost to history.
 
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I'm wondering if anybody has figures for the dimensions of the J58 such as the overall length, inlet, and nozzle diameters?
 

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