“You know the part in ‘High Flight’ poem where it talks about putting out your hand to touch the face of God? Well, when we were ‘at speed and altitude’ in the SR we had to slow down and descend in order to do that,” Gil Bertelson, former SR-71 Blackbird driver
The following story appears in John Altson book The Black Line.
The poem reads as follows:
Oh! I have slipped the surly bonds of Earth
And danced the skies on laughter-silvered wings;
Sunward I’ve climbed, and joined the tumbling mirth
Of sun-split clouds, — and done a hundred things
You have not dreamed of — wheeled and soared and swung
High in the sunlit silence. Hov’ring there,
I’ve chased the shouting wind along, and flung
My eager craft through footless halls of air… .
Up, up the long, delirious burning blue
I’ve topped the wind-swept heights with easy grace
Where never lark, or ever eagle flew —
And, while with silent, lifting mind I’ve trod
The high untrespassed sanctity of space,
Put out my hand, and touched the face of God.
Former SR-71 Blackbird driver Gil Bertelson’s response to the queries was, “I can’t give you exact numbers, but I can give you something to relate to … you know the part in “High Flight” where it talks about putting out your hand to touch the face of God? Well, when we were “at speed and altitude” in the SR we had to slow down and descend in order to do that.”
The Limiting Factor for the SR-71
Believe it or not according Bertelson (who passed away on Dec. 7, 2017), the limiting factor in the speed of the SR-71 was what was known as CIT — Compressor Inlet Temperature. The maximum allowable CIT was 427 degrees Centigrade. Above that temperature, the engines would begin to burn up. On a “standard lay” (temperature wise), the outside air temperature at the SR-71’s operating altitudes would be minus 56 degrees Centigrade. On one of those “standard temperature” days, the CIT would reach the limiting 427 degrees as the aircraft was accelerated to Mach 3.2. If the outside air temperature was warmer than standard (say minus 52 degrees), the CIT would reach 427 degrees prior to reaching Mach 3.2. Conversely, if the outside air were colder than standard (say minus 60 degrees), the 427-degree CIT would be reached at a higher Mach number. There were occasions, especially when flying out of Okinawa, where the outside air temperature was considerably warmer than standard. If it was warm enough, missions might have to be aborted due to fuel considerations. The airplane was not as fuel efficient in warm air as it was in cold air.
Gil remembers one mission flown over the Barents and Arctic Seas when the outside air temperature was showing minus 90 degrees Centigrade, or 34 degrees colder than standard. Due to that extremely cold air, the airplane reached 90,000 feet and the slowest speed he could maintain was 3.15 Mach. Turn starting points and bank angles had to be manually adjusted to avoid getting too close to the Soviet Union’s land mass. When they rendezvoused with the tankers for their next in-flight refueling, he and Frank Stampf (his Reconnaissance Systems Officer or RSO) had 12,000 pounds (nearly 2,000 gallons) more fuel on board than the flight plan called for. Those J-58 engines loved cold air.
Gil also remembers one mission that was flown in the late afternoon into evening. There were several in-flight refuelings and several climbs around 85,000 feet. Due to the route of the mission, on two occasions they actually climbed out of darkness heading to the West and caught up with the sun to witness sunrises in the West. So, on that particular day he got to witness three sunrises — one in the East as the day began and then two in the West as he was outracing the sun.
The Black Line is available to order here.
Photo credit: Lockheed Martin, U.S. Air Force
Artwork courtesy of AircraftProfilePrints.com