Talk:Pratt & Whitney J58

Re-do my edits of Jan 2013

I was never really happy with the stuff I did so will now improve on it. At the same time I'll compartmentalise and verify the other stuff.Pieter1963 (talk) 01:35, 26 March 2014 (UTC)

This article relies on references to primary sources - flagged in 2014

Unless someone can be specific about the primary sources and why they are not acceptable for this particular article I will delete the header.Pieter1963 (talk) 13:49, 26 March 2014 (UTC)

Specification of J58-P-4

According to Jack Connors book the J58-P-4 was a non-afterburning version for the A3J. He says the correct designation for the Blackbird application was JT11D-20 so it's the specs for this one that are more relevant. I will modify.Pieter1963 (talk) 13:59, 26 March 2014 (UTC)

Ref JC book again, I will delete reference 21 as a source of reliable information since it uses the incorrect designation for the SR-71 engine as well as the wrong airflow (450lb/s). This questions validity of sfcs also. If the specs are really meant for the J58-P-4 they are also incorrect eg doesn't have afterburning.Pieter1963 (talk) 20:14, 20 May 2014 (UTC)

Under Variants, the article now has : "JT11D-20 (J58-P-4) Production version for the SR-71." - Does that need correcting ? - Rod57 (talk) 09:59, 30 June 2023 (UTC)

... at high speed, sent air from after the first four rows of compressors straight to the afterburner section, making it a type of turboramjet

This is a very popular statement but begs the question "In what way?" What happens at high speed (M3.2?)that makes it like a turboramjet? It appears insightful but leaves the inquisitive reader hanging with no explanation.Pieter1963 (talk) 03:21, 16 January 2015 (UTC)

moved cite 3 to powerplant section, deleted cite 4 as both statements on this topic are incorrect. Replaced previous statement with explanation using credible sources. Have not linked to turboramjet as the example given there is a very unique paper-only study which I don't think is helpful since the J58 is equally unique and will be explained in detail with its own section.Pieter1963 (talk) 23:21, 16 January 2015 (UTC)

Citations required

A request for additional citations needs to refer to specific sentences. Please provide same. Cheers.Pieter1963 (talk) 18:18, 10 December 2018 (UTC)

Note that there are several paragraphs in the article that do not have a citation at the end or have no citations at all. -Fnlayson (talk) 18:43, 10 December 2018 (UTC)

All sections now seem to have citations so am removing the global notice. There is one para (Intake) with no citation eg for the M 0.4, so I put a cn on just that. - Rod57 (talk) 11:24, 1 May 2020 (UTC)

Loosely connected section

"The afterburning turbojet at Mach 3 and the J58 as a turboramjet" section seems poorly connected to the rest of the article. To me the first 2 paragraphs now do not show a clear connection to the J58. The last two paragraphs on the original J58 seems like background and as such should be combined with earlier info in the article instead of being repeated later, imo. Regards, -Fnlayson (talk) 15:01, 13 December 2018 (UTC)

I've deleted the section and relocated a small part of it. Further comments welcome.Pieter1963 (talk) 16:50, 14 December 2018 (UTC)

Thanks. I didn't mean for so much to be deleted, but whatever you think is appropriate. -Fnlayson (talk) 19:47, 14 December 2018 (UTC)

What was the designation of the version with the 6 bypass tubes

The section Re-design for Mach 3.2 does not seem to give the designation of the modified engine (with the 6 bypass tubes) - and the minimal Variants section does not help. - Rod57 (talk) 11:49, 1 May 2020 (UTC)

JT11-20 / J58-1. There were earlier versions of the JT11/J58 designed for Mach 3 dash capability, but which could only do so for up to 15 minutes. The JT11-20 was the redesign for Mach 3.2 cruise. The JT11D-20 was apparently the production version, though my source is unclear on that. (Pratt used the letters A-D for various stages of development and production. Later the D came to mean a turbofan version of a turbojet design, as with the JT3D and JT8D.) I'll see if I can add a few more details to the article, with sources. - BilCat (talk) 20:11, 1 May 2020 (UTC)

Connor's book says the tubed engine is JT11D-20. Dr. Bob Abernethy, tube inventor/patent holder, says it's a JT11-D20 (see his "Never Told Tales of P&W" cited in article). Bob's boss, Bill Brown, in his "J58/SR-71 Propulsion Integration" paper says it's the JT11-D20.

BB also says that the engine prior to that, which completed 700 hours testing, would have a dash capability up to Mach 3 for several seconds. This appears to have been optimistic because I presume they didn't have a good model of it at the time, ie BA's first job was to create a computer program to calculate the performance of the J58 for the Lockheed studies and he found it would never get to Mach 3, ref surging/no thrust from turbomachine/ melted afterburner at Mach 2.5 (again see NTT of P&W).Pieter1963 (talk) 20:12, 14 June 2020 (UTC)

Did the J58 generate electrical power for the aircraft

Did the J58 generate electrical power for the aircraft ? If so, was the generator part of the engine, or driven mechanically ? - Rod57 (talk) 10:08, 30 June 2023 (UTC)

According to the SR-71 flight manual each engine drove a 60 kVA generator through a constant speed drive (which would be part of the accessory drive). A fairly common arrangement, I believe the B-52 used bleed air turbines to drive generators (prone to exploding in early models). In my experience of engine changes (Lightning, F-4 Phantom, Buccaneer) any accessories like generators and hydraulic pumps would be removed and transferred to the replacement engine. Nimbus (Cumulus nimbus floats by) 14:23, 30 June 2023 (UTC)

https://www.cia.gov/readingroom/print/1953380 This link has a more readable pdf attachment concerning the remote gearbox, originally to be a Lockheed design responsibility but swapped with the ejector nozzle which was originally P&W as part of the engine. So P&W did the gearbox and the nozzle became part of the airframe structure. After alot of gearbox mount and drive shaft wear it was found that the gearbox moved 4 inches relative to the engine which was fixed with a drive shaft with double universal joints.Pieter1963 (talk) 17:14, 19 August 2023 (UTC)