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Lockheed XJ37 turbojet engine

Steve Pace

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The proposed 5,000lb thrust Lockheed XJ37 axial-flow turbojet engine was ahead of its time. Two of them were to propel the proposed Lockheed L-133 interceptor pursuit. Lockheed eventually sold the engine to Menasco (I think?) but I don't know what happened to it after that.
 

aim9xray

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I had the chance this last weekend to visit the Planes of Fame Museum at Chino, California. In the "early jets" hangar, I found an example of the L-1000 / XJ37 engine. In the 60-odd years since it's creation, the engine has suffered some "hangar rash" (dents and dings); in addition it appears that almost all of the external tubing and wiring is missing (if it was there to begin with - this may have been an engineering mockup from the beginning).

Several features are noteworthy - the large number of fuel injectors is unusual to say the least. Note also the ejector exhaust that draws outside air into the tailpipe for added thrust and to create a boundary layer of cooling air to protect the tailpipe stricture.
 

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KJ_Lesnick

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aim9xray


I had the chance this last weekend to visit the Planes of Fame Museum at Chino, California. In the "early jets" hangar, I found an example of the L-1000 / XJ37 engine.


Several features are noteworthy
Almost everything on that engine was noteworthy: It had a twin-spool compressor of which the LP and HP had sixteen stages apiece; the compressor lacked discs as would normally be seen -- the blades were mounted to a drum. The first four stages actually were hydraulically clutched, and inter-cooling was located between the HP and LP spools. Though earlier models had a can-annular configuration, this model had an annular configuration.


Note also the ejector exhaust that draws outside air into the tailpipe for added thrust and to create a boundary layer of cooling air to protect the tailpipe stricture.
The exhaust was used to pull turbulent air from the top and bottom of the wing which form particularly at high subsonic speed (it was designed to go supersonic at least in a dive). Such airflow would provide cooking for the tailpipe which had an afterburner by 1940-1941.


the large number of fuel injectors is unusual to say the least.
How many fuel injectors did it have?
 

aim9xray

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KJ_Lesnick said:
the large number of fuel injectors is unusual to say the least.
How many fuel injectors did it have?

With reference to the photo above (titled "L-1000 Fuel Injection"), count the number of "pigtails" leading from the manifold to the fuel injectors. Multiply by two (to account for those hidden on the other side) and report back.

When you do, we can discuss why the descriptions on Wikipedia are sadly and grossly out of sync with the actual hardware that was produced.
 

aim9xray

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Great! One question answered. I was counting 24-25 visible, so we are in the ballpark.

OK, then - lets start at the front of the engine. Wikipedia stated that there were 16 stages of low pressure compressor and 16 stages of high pressure compressor with intercooling between them. (Nevermind the "four stages hydraulically clutched").

Looking at the photos of the hardware (and from general turbojet knowledge), I don't think that is so. What would lead me to me to that opinion?

(And while we are looking at the front of the engine, why do you think that the front frame has some 90 degree plumbing fittings attached?)
 

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aim9xray


Great! One question answered.
Understood...


OK, then - lets start at the front of the engine. Wikipedia stated that there were 16 stages of low pressure compressor and 16 stages of high pressure compressor with intercooling between them. (Nevermind the "four stages hydraulically clutched").
Understood...

Looking at the photos of the hardware (and from general turbojet knowledge), I don't think that is so. What would lead me to me to that opinion?
I'm unsure... maybe the compressor looks too short to stuff that many stages of compressors in there?

(And while we are looking at the front of the engine, why do you think that the front frame has some 90 degree plumbing fittings attached?)
I'm not sure though you'd typically use plumbing fittings in a jet to pump in fuel or oil for lubrication...
 

tartle

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Busy editing book at moment so will look at this engine later...in meantime from the Tardis-like tea chest....
tbc
 

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tartle

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Has anyone got access to SAE papers... apparently this has some stuff on Menasco (for Lockheed) gas turbines:
Rinek, L., "Menasco Aircraft Engines: Air Racing Paragon of the 1930s," SAE Technical Paper 965598, 1996
 

aim9xray

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KJ_Lesnick said:
OK, then - lets start at the front of the engine. Wikipedia stated that there were 16 stages of low pressure compressor and 16 stages of high pressure compressor with intercooling between them. (Nevermind the "four stages hydraulically clutched"). Looking at the photos of the hardware (and from general turbojet knowledge), I don't think that is so. What would lead me to me to that opinion?
I'm unsure... maybe the compressor looks too short to stuff that many stages of compressors in there?
That's a good observation. The best way to get to ground truth would be to split the case and count the stages, but I don't think that Mr. Maloney would let us do that to his exhibit. Let's attack this by analogy. What was the state of the art at the time and for some years after? Go find the number of compressor stages for the following engines and report back. (also note thrust and compression ratio)
- Avon
- Sapphire
- J30
- J34
- J35
- J40
- J47
- J79

(And while we are looking at the front of the engine, why do you think that the front frame has some 90 degree plumbing fittings attached?)
I'm not sure though you'd typically use plumbing fittings in a jet to pump in fuel or oil for lubrication...
Well, I was being a bit generic in my description. To be technical, those would be "AN" standard aviation fluid fittings - but why do you think that they would pump a fluid through the engine front frame? (Hint: take a close look at Tartle's photo.)
 

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aim9xray


That's a good observation. The best way to get to ground truth would be to split the case and count the stages, but I don't think that Mr. Maloney would let us do that to his exhibit.
Curators get so bent out of shape over that... *laughs*


Let's attack this by analogy. What was the state of the art at the time and for some years after?
During the early 1940's there weren't many axial flow engines out there. These engines would include the BMW 003 (1940), Jumo 004 (1940), (possibly the HeS 8 and 11), the Metropolitan F.2/4 Beryl (1941), the Metropolitan Vickers F.3 (Turbofan technically).


There are certainly others that were run...


Go find the number of compressor stages for the following engines and report back. (also note thrust and compression ratio)
Wilco...


Avon: 15-stage axial; 12,690 lb thrust; 7.45:1 (PR)
Sapphire/J-65: 13-stage axial; 7,239 lbf; 7:1 (PR)
J30: 6-stage axial; 1,600 lbf; 3:1
J34: 11-stage axial; 3,400 lbf; 4.35:1
J35: 11-stage axial; 5,600 lbf; 5.5:1
J40: 10-stage axial; 7,500 lbf; 5.2:1
J47: 12-stage axial; 5,800 lbf; 5.5:1
J79: 17-stage axial; 11,905 lbf; 13.5:1

Well, I was being a bit generic in my description. To be technical, those would be "AN" standard aviation fluid fittings - but why do you think that they would pump a fluid through the engine front frame? (Hint: take a close look at Tartle's photo.)
The tubing flows through a structure in the middle of the engine which might be the intercooler that was mentioned; it then flows through to the afterburner in three locations which appear to include the fuel injectors and two other spots.
 

tartle

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It might be worth plotting them onto this graph to get a feel for the technology maturity of these engines. It is from 'Aeronautical Research in Germany' by Hirschel, Prem and Madelung.
 

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KJ_Lesnick

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Tartle


It might be worth plotting them onto this graph to get a feel for the technology maturity of these engines. It is from 'Aeronautical Research in Germany' by Hirschel, Prem and Madelung.
32 stages goes right off the chart, it would appear you'd have around 20:1...
 

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It seems the two 16 stage spool configuration is a figment of someone's artistic sketchings. A single 16-stage machine seems to be what was built!
 

robunos

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tartle said:
It seems the two 16 stage spool configuration is a figment of someone's artistic sketchings. A single 16-stage machine seems to be what was built!

Just a thought, do you think that they may have been counting the rotors and stators separately? 16 rows of rotors and 16 rows of stators makes 32...

cheers,
Robin.
 

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A couple of pages from two of Nathan Price's Lockheed patents.
They are of the right time to be accurate in the description of compressor etc, so should help us understand the photos in thread.
 

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aim9xray

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He's not dead, he's resting!
 

Sherman Tank

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Is there any solid information available on why development of the XJ37 sputtered out after what seems to have been a promising start? After being passed off to Menasco development kept going until 1953, but there's almost nothing describing any results obtained. Has anyone written this story up somewhere?
 

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Is there any solid information available on why development of the XJ37 sputtered out after what seems to have been a promising start? After being passed off to Menasco development kept going until 1953, but there's almost nothing describing any results obtained. Has anyone written this story up somewhere?
"By the time it was developed enough for production use, other engines, often British-derived, had surpassed it in performance. The design was later converted to a turboprop, the T35 and still later sold to Wright Aeronautical, where it saw some interest for use on what would become the B-52 Stratofortress, before that design moved to jet power. The J37 and T35 were built to the extent of a number of testbed examples but never entered production." That is straight from Wikipedia, dont know how reliable that info is.
 

aim9xray

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I'd rate that as unlikely, J37 was axial flow and T35 was centrifugal flow.
 

Jargo

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Most sources state that the J37 was just killed off in the 1950's, so that might be the true answer.
 

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