John C. Evans discusses the development of the P&W J-58 engine used in the A-12 and SR-71 Aircraft

Pratt & Whitney Aircraft J-58 (JT11D-20) Characteristics’.
Maximum Thrust           34,000 Lb
Military Thrust              23,900 Lb
Weight                         6,250 Lb
Length                         215.940 In
Maximum Diameter      55.43 In
Sea Level Air Flow        326 Lb/Sec
Compression Ratio       8.5:1
Total Pressure Ratio    2,93:1
Bleed Bypass Ratio      20-40% (above Mn 2.0 Only)
Pratt & Whitney Aircraft J-58 (JT11D-20) Engine Milestones.
Program Milestones (Firsts)
1st Engine Rated for Continuous Military Operation (Military Thrust equal to 23,900 LbFn).
1st Engine Rated for Continuous Afterburning Operation (Afterburning Operation Duty Cycle limited to 5 Minutes of previous Turbojet Engines.
1st Use of Fuel as Engine Hydraulic Fluid (Necessary for Heat Rejection).
1st Use of Directionally Solidified Turbine Airfoils.
1st Dual Cycle Production Engine (Turbojet & Hi-Bypass Turbojet), Afterburning Turbo-Jet below Mn=2.0 and Hi-Bypass (20-40%) Turbojet above Mn=2.0.  Bypass air used to increase engine airflow and to cool Turbine & Afterburner sections.
1st Application of Variable Orifice Afterburner Spray-bars.
Production Quantities (Total 171 Engines)
Experimental       11 (XD-1 thru XD-11)
Development      10 (FX111 thru FX120)
Prototype            51 (P648201 thru P648251)
Production          99 (P648301 thru P648399)
As unique as the P&WA J-58 Engines were, the truly amazing thing is what the Lockheed Martin A-12 (and subsequent Blackbirds) were able to accomplish when fitted with two J-58 Engines.
Lockheed Martin A-12 CIA Oxcart Aircraft Milestones.
Maximum Speed          Mach 3.2+
Maximum Altitude        85,000 Feet MSL+
Maximum Range          2,500 Miles+ (A-12, YF12A, & M21 without Inflight Refueling).
3,500 Miles + (SR-71 without Inflight Refueling)
 With Inflight Refueling Limited to onboard CO2 (to inert Aircraft Fuel Tanks eliminating Oxygen and possibility of Fire/Explosion) and Pilot endurance.
Everything had to be invented.
During Mach=3.2+ flight the real enemies are heat buildup from air friction, and the massive heat generated by the PWA J-58 Engines.
         The Aircraft structures were built using Beta Titanium and some High Temperature Plastics/Quartz.
         The Engines were almost all high Chrome Nickel Alloys (with the exception of the engine Inlet Case, 1st Stage Stator, and 1st Stage Blades that were Titanium Alloys.
         Engine Fuel JP-7 (PWA 523)
         Engine Lubricating Oil (PWA 524)
         Engine Hydraulic Oil (Use JP-7 Engine Fuel) and Engine/Aircraft method of heat rejection to prevent overheating/Coking of fluid)
         Aircraft Inlet Spikes (to condition Engine Inlet Air) and Nacelles Cooling Airflow (to increase thrust and prevent structure overheating and failure)


John C. Evans, Biography

10/28/1935    I was born in Clawson, Oakland, Michigan a small suburb just six miles north of Detroit, Michigan.

1940 – 1953   I attended Kinder-Garden, Grade School, and High School in Clawson, Michigan.

1/1954              I moved to Royal Oak, Michigan just prior enlisting in the United States Air Force.

2/26/1954      I enlisted in the United States Air force in Detroit, was sent to Sampson AFB, NY for basic training, and then sent to Amarillo AFB Texas for Medium Bomber Training.

10/1954         After Tech School I had two weeks leave and then was sent to Pine Castle AFB, Florida arriving in November 1954, just south of Orlando FL, as my first duty station.  Later my Squadron moved to our permanent duty station at Homestead, Florida just south of Miami.  In 1956 and 1957 I was deployed TD (Temporary Duty) to French Morocco for a total of 5 months and 9 days.

10/29/1957    I separated from the United States Air Force with an “early out” for military downsizing.

10/1957 – 8/1958   Worked for Newsome and Holmes Tile Company located in Conway, FL as a Helper/Apprentice.

8/26/1958 – 11/15/1968   I was hired by Pratt & Whitney Aircraft Research & Development located in the Florida Everglades just 16 miles NW of West Palm Beach, FL as a Jet Assembler.  I would work on the JT11D-20 program for just over 10 years.  I was later to learn that this engine was designated as the J-58 and would power the Lockheed Martin Blackbird family of aircraft.

12/2/1958 – 2/1/2001      I was hired by Airesearch Mfg. Co. of California as a Laboratory Technician.  During my employment the company would go through several name changes and mergers.   On April 1, 1984 I transferred to Garrett Phoenix, AZ and continued my employment for a total of just over 32 years. These name changes were, Allied Signal Cos., GTEC, GED, and Honeywell.  I retired from Honeywell as an Engineering Specialist, Controls, on 2/1/2001.  From joining the USAF until my retirement from Honeywell I have worked in Aviation for an uninterrupted career of 47 years.

1993 – Present      I keep busy with volunteer work.  Some of my volunteer work is, Maricopa County Sheriff’s volunteer Posse as a Firearms Instructor & Weapons Inspector (1993-2002), volunteer Joe Foss Institute (WWII Medial of Honor), and volunteer Veterans History Project.  In addition I am a current member or both the Roadrunners Internationale <> and the Blackbird Association <>.

I also am the Curator of the “ATF3 Online Museum” at

I have recently been interviewed by both Steve Kates aka DrSky & <>, and his brother Joe Kates CEO of <>.

I currently live in Tempe, Maricopa, Arizona 10 miles SE of Phoenix AZ.

Mechanic P&WA JT11D-20 (J-58) 8/1958-11/1968

Member: Roadrunners Internationale <>

Member: Blackbird Association <>
Member: American Legion <>
Member: AzCDL <>
Volunteer Veteran, Joe Foss Institute, since 2009 <>
Volunteer Veterans History Project, since 2010 <>
Curator: ATF3 Online Museum <>


Dave Budd

Hi..I'm Dave. Webmaster here at Photorecon. The boss also laughs and says I'm the Chief Photographer. I live in Las Vegas and I cover most of the West Coast events with Joe. I do most of the upkeep of the site.

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