J58 Last Run


The evening of Thursday, September 12, 2002 was probably the last time a Pratt & Whitney J58 will fill the night sky at Edwards with noise and light.

To experience a J58 in full burner close up and personal is hard to describe. Picture a gigantic blow torch, 40 inches in diameter, putting out a blue-yellow-orange flame over 50 feet long. Imagine standing 30 feet from this, feeling the vibration and heat. You wear both foam plugs and earmuffs. Your ears still ring afterward, because the sound is conducted through your body. The back half of the engine transforms from dull gray to bright orange, seemingly transparent. The flame has little three-dimensional diamond shaped shock patterns about every two feet. I lost count at 13. It is both frightening and beautiful, an amazing demonstration of perfectly controlled power. And to think - this was done with 1950s technology.

A Pratt & Whitney J58 in the test stand at Edwards AFB preparing for the last run of this great engine. Note the beefy cables and steel rods to tie this giant down.  

 

Two J58s powered the SR-71 Blackbird. Individually, they have more horsepower than the Queen Mary. On a typical flight at Mach 3.2 and 80,000 feet, two engines would burn in excess of 100,000 pounds of fuel in a little over one hour.

J58 in Full Afterburner. Note how the whole aft section is glowing with the heat. Note also the shock diamonds.

 

 

NASA was the last organization to operate SR-71s. With the end of any flying of the aircraft, NASA was slowly disposing of the associated assets. Examples can be found in various museums around the country, having had their wings cut off for transportation and then tacked back on for display.

NASA still had something like 40-50 engines, most of them in flyable storage condition. One NASA center asked for three of the engines for testing purposes, so we had to prepare them for shipment and ensure that they were functioning. We also had promised the base commander that we would dispose of the remaining stock of JP-7, the exotic fuel that was specially formulated to withstand both the very cold environment at 80,000 feet and the very hot environment of the engine nacelle.

The best way to dispose of this fuel is to -- BURN IT. We also had to ensure that the triethylborane (TEB) was purged from the engine. TEB, which ignites upon contact with air, is used to start the engine and light the afterburners. Each engine carries enough TEB for any combination of at least 16 starts or lights.

J58 burning off the remaining TEB (triethylborane) in the lines. The JP-7 fuel is so inert that it must be kindled by use of TEB, which ignites spontaneously on contact with oxygen. Each J58 on the SR-71 carries sufficient TEB for any combination of at least 16 starts or afterburner lights.

 

Amazingly, NASA was able to assemble a team that still knew how to do this - most of them were still working for Pratt & Whitney at Edwards AFB. The former top sergeant of the detachment that worked the SRs for most of his AF career worked for NASA. Also amazing is that of the four engines removed from their shipping containers, three worked liked the day they were made (the forth had a broken line).

After the run, everyone stayed for cake donated by the P&W folks. The guys who ran the test stand posed for photos in front of the engine. There were actually some tears shed. These guys loved that program!

J58 Running Hot. This was probably the last time an SR-71 engine will be run at Edwards. The noise and heat were incredible!  

 


 

Images of a P&W J58 on display in Palmdale, California, next to the entrance of AF plant 42.

Contributed by Robert Nocera