Great SR-71 Story - How slow could it fly?

Homerboy

Lifer
Mar 1, 2000
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http://foxtrotalpha.jalopnik.com/the-sr-71-blackbirds-most-spectacular-flyover-was-also-1719654907


The SR-71 Blackbird's Most Spectacular Flyover Was Also Its Slowest
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Tyler Rogoway
Filed to: BLACKBIRDS 7/23/15 10:23am
The SR-71 Blackbird's Most Spectacular Flyover Was Also Its Slowest

One of the most legendary stories related to the SR-71 Blackbird has nothing to do with how fast or how high it could fly. Quite the opposite really, it has to do with how slow and low it flew, somewhat accidentally, the results of which was probably one of the most spectacular visual and audible moments in aviation history to behold.

The story comes from retired U.S. Air Force Maj. Brian Shul, and it was posted by our friends over at Sierra Hotel Aeronautics who generously allowed us to share it here. Here’s Shul on the Blackbird’s speed:

“As a former SR-71 pilot, and a professional keynote speaker, the question I’m most often asked is ‘How fast would that SR-71 fly?’ I can be assured of hearing that question several times at any event I attend. It’s an interesting question, given the aircraft’s proclivity for speed, but there really isn’t one number to give, as the jet would always give you a little more speed if you wanted it to. It was common to see 35 miles a minute.

Because we flew a programmed Mach number on most missions, and never wanted to harm the plane in any way, we never let it run out to any limits of temperature or speed.. Thus, each SR-71 pilot had his own individual ‘high’ speed that he saw at some point on some mission. I saw mine over Libya when Khadafy fired two missiles my way, and max power was in order. Let’s just say that the plane truly loved speed and effortlessly took us to Mach numbers we hadn’t previously seen.

So it was with great surprise, when at the end of one of my presentations, someone asked, ‘What was the slowest you ever flew the Blackbird?’ This was a first. After giving it some thought, I was reminded of a story that I had never shared before, and I relayed the following.

I was flying the SR-71 out of RAF Mildenhall, England, with my back-seater, Walt Watson; we were returning from a mission over Europe and the Iron Curtain when we received a radio transmission from home base. As we scooted across Denmark in three minutes, we learned that a small RAF base in the English countryside had requested an SR-71 fly-past. The air cadet commander there was a former Blackbird pilot, and thought it would be a motivating moment for the young lads to see the mighty SR-71 perform a low approach. No problem, we were happy to do it. After a quick aerial refuelling over the North Sea, we proceeded to find the small airfield.

Walter had a myriad of sophisticated navigation equipment in the back seat, and began to vector me toward the field. Descending to subsonic speeds, we found ourselves over a densely wooded area in a slight haze. Like most former WWII British airfields, the one we were looking for had a small tower and little surrounding infrastructure. Walter told me we were close and that I should be able to see the field, but I saw nothing. Nothing but trees as far as I could see in the haze. We got a little lower, and I pulled the throttles back from 325 knots we were at. With the gear up, anything under 275 was just uncomfortable. Walt said we were practically over the field-yet; there was nothing in my windscreen. I banked the jet and started a gentle circling maneuver in hopes of picking up anything that looked like a field. Meanwhile, below, the cadet commander had taken the cadets up on the catwalk of the tower in order to get a prime view of the fly-past. It was a quiet, still day with no wind and partial gray overcast. Walter continued to give me indications that the field should be below us but in the overcast and haze, I couldn’t see it. The longer we continued to peer out the window and circle, the slower we got. With our power back, the awaiting cadets heard nothing. I must have had good instructors in my flying career, as something told me I better cross-check the gauges. As I noticed the airspeed indicator slide below 160 knots, my heart stopped and my adrenalin-filled left hand pushed two throttles full forward. At this point we weren’t really flying, but were falling in a slight bank. Just at the moment that both afterburners lit with a thunderous roar of flame (and what a joyous feeling that was) the aircraft fell into full view of the shocked observers on the tower. Shattering the still quiet of that morning, they now had 107 feet of fire-breathing titanium in their face as the plane levelled and accelerated, in full burner, on the tower side of the infield, closer than expected, maintaining what could only be described as some sort of ultimate knife-edge pass.

Quickly reaching the field boundary, we proceeded back to Mildenhall without incident. We didn’t say a word for those next 14 minutes. After landing, our commander greeted us, and we were both certain he was reaching for our wings. Instead, he heartily shook our hands and said the commander had told him it was the greatest SR-71 fly-past he had ever seen, especially how we had surprised them with such a precise maneuver that could only be described as breathtaking. He said that some of the cadet’s hats were blown off and the sight of the plan form of the plane in full afterburner dropping right in front of them was unbelievable. Walt and I both understood the concept of ‘breathtaking’ very well that morning and sheepishly replied that they were just excited to see our low approach.

As we retired to the equipment room to change from space suits to flight suits, we just sat there-we hadn’t spoken a word since ‘the pass.’ Finally, Walter looked at me and said, ‘One hundred fifty-six knots. What did you see?’ Trying to find my voice, I stammered, ‘One hundred fifty-two.’ We sat in silence for a moment. Then Walt said, ‘Don’t ever do that to me again!’ And I never did.

A year later, Walter and I were having lunch in the Mildenhall Officer’s club, and overheard an officer talking to some cadets about an SR-71 fly-past that he had seen one day. Of course, by now the story included kids falling off the tower and screaming as the heat of the jet singed their eyebrows. Noticing our HABU patches, as we stood there with lunch trays in our hands, he asked us to verify to the cadets that such a thing had occurred. Walt just shook his head and said, ‘It was probably just a routine low approach; they’re pretty impressive in that plane.’

Impressive indeed.”

Thanks again to Sierra Hotel Aeronautics. They make the coolest aviation related apparel and gear out there. I love their stuff, make sure to check them out.
 

Fritzo

Lifer
Jan 3, 2001
41,920
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I thought the SR-71 HAD to fly fast so it's skin would heat up enough to seal the fuel tank. It leaked all over the place during takeoff.
 

JoeBleed

Golden Member
Jun 27, 2000
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this is one of those stories i'd love to be witness to both aspects of pilot and cadet on the tower. just awesome.
 

alien42

Lifer
Nov 28, 2004
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I thought the SR-71 HAD to fly fast so it's skin would heat up enough to seal the fuel tank. It leaked all over the place during takeoff.

it does, but i am sure it takes some time sitting on the tarmac to cool off enough to start leaking again.
 

Genx87

Lifer
Apr 8, 2002
41,091
513
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Listening to F-16s on a near daily basis using their afterburners to go vertical. I can only imagine how loud an SR-71 with full afterburner.
 

PokerGuy

Lifer
Jul 2, 2005
13,650
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I'm guessing that day there were underwear changes required for the cadets who saw the plane from the tower/field as well as for the two pilots!

Thanks for sharing.
 

K7SN

Senior member
Jun 21, 2015
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I have a couple A-12 stories (One from 1963) and know where one A-12 plowed into the ground but someone cleaned up most pieces parts before I could ride my motorcycle to the crash site without getting arrested or shot. They say the RS-71 (yeah that's one of the names it was called before Johnson's feud with Goldwater) holds the speed record but the A-12 flew faster and higher. If I could find it I have a photo of the tarmac at the ranch with A-12s and SR-71s lined up. I had it along with an early same view picture of a bunch of U-2s. Sure glad all that is declassified and I took them home when Lockheed Martin closed our office and told me to work from home.
 

BUTCH1

Lifer
Jul 15, 2000
20,433
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Truly a "cool story bro", @152 knots that baby had to have been close to a stall event.
 

Blackjack200

Lifer
May 28, 2007
15,995
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They would have been falling rapidly. Usually if you're at stall speed, you need to apply power and nose down, but the rules are different when you have 70,000 pounds of thrust.
 

Blackjack200

Lifer
May 28, 2007
15,995
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it does, but i am sure it takes some time sitting on the tarmac to cool off enough to start leaking again.

So did they pump the excess fuel back out of the bird when it was done with a mission? I know that when it was fuelled up the JP-7 was freezing cold so it could be circulated as coolant before being sent to the engine.
 
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IndyColtsFan

Lifer
Sep 22, 2007
33,655
687
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I was at the USAF museum last weekend and saw an SR71 for the first time. Damn, that's an impressive plane.
 

garndawg

Member
Feb 29, 2008
88
1
71
152kts = 1.048 X Stall Speed

On edge...sheesh

Another lil comment, Vmc with one engine out was in excess of 200kts. So if you lost an engine below that, bye bye...
 

Ferzerp

Diamond Member
Oct 12, 1999
6,438
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Another lil comment, Vmc with one engine out was in excess of 200kts. So if you lost an engine below that, bye bye...

They also tended to have to restart those engines pretty often didn't they? That was only after it was in ram jet mode though if I remember correctly.
 

dphantom

Diamond Member
Jan 14, 2005
4,763
327
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Remember a story from when I was stationed at ellsworth AFB some time ago about radio chatter between an SR-71 and the control tower. The Sr-71 radioed requesting clearance for 80,000 feet. The response back from the tower was "sure if you can climb that high" or words to that effect.

The SR-71 radioed back "descending to 80,000".

Not sure if apocryphal or not but found it funny at the time. Sr-71 was (is) an amazing piece of technology.
 

Blackjack200

Lifer
May 28, 2007
15,995
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They also tended to have to restart those engines pretty often didn't they? That was only after it was in ram jet mode though if I remember correctly.

From Wikipedia (article on the J58 engine)

The engine's high operating speeds and temperatures required a new jet fuel, JP-7. Its reluctance to be ignited required triethylborane (TEB) to be injected into the engine to ignite it and the afterburner. Above -5 °C, TEB spontaneously ignites in contact with air. Each engine carried a nitrogen-pressurized sealed tank with 600 cm3 (20.7 ounces) of TEB, sufficient for at least 16 starts, restarts, or afterburner lights; this number was one of the limiting factors of SR-71 endurance, as after each air refueling the afterburners had to be reignited.[20] When the pilot moved the throttle from cut-off to idle position, fuel flowed into the engine, and shortly afterwards an approx. 50 cm3 (1.7 ounce) shot of TEB was injected into the combustion chamber, where it spontaneously ignited and lit the fuel with a green flash. In some conditions, however, the TEB flow was obstructed by coking deposits on the injector nozzle, hindering restart attempts. Refilling the TEB tank was a perilous task; the maintenance crew wore silver fire suits.[21] Conversely, the JP-7 fueling was so safe that some aircraft maintenance was permitted during filling. The chemical ignition was chosen instead of a conventional igniter for reliability reasons, and to reduce mechanical complexity. The TEB tank is cooled with fuel flowing around it, and contains a disk that ruptures in case of overpressure, allowing TEB and nitrogen to discharge into the afterburner.

Goddamn, there are so many awesome things about this plane.

Remember a story from when I was stationed at ellsworth AFB some time ago about radio chatter between an SR-71 and the control tower. The Sr-71 radioed requesting clearance for 80,000 feet. The response back from the tower was "sure if you can climb that high" or words to that effect.

The SR-71 radioed back "descending to 80,000".

Not sure if apocryphal or not but found it funny at the time. Sr-71 was (is) an amazing piece of technology.

Nice story! love the SR-71. Maybe my favorite machine of all time.
 

Blitzvogel

Platinum Member
Oct 17, 2010
2,012
23
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Holy christ, so 152 knots while in a "banked" turn? I'm surprised they didn't crash the plane. Technically the plane should produce quite a bit of body based lift thanks to the chines. As alpha increases, lift increases just like a regular wing because of it's relatively flat bottom thanks to the chines but also because of the addition of vortex lift that comes from LERXs and delta wings. I assume vortexs are created at the nose where the chines begin, as well as where the wings begin, and once again where the outboard portions of the wings begin from the engines. 'Gonna need all that lift, even at Mach 3+ to reach those crazy altitudes. As impressive as it was, I appreciate the XB-70 Valkyrie's method for high altitude lift production more though, mostly because it looks cooler :awe:

in-flight.jpg
 
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