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Flightline Friday: Flying the SR-71 at greater than Mach 3.5 February 13, 2015

Posted by Tantumblogo in Admin, awesomeness, Flightline Friday, fun, history, non squitur, silliness, Society, technology.
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It’s been a more or less open secret in defense circles for decades that the Air Force has constantly under-rated the performance of both the U-2 and the763wsr71 SR-71.  The U-2 was capable of flying far higher than the officially published figure of 70,000 ft (even if the increasing weight of the sensors it carries has limited that capability somewhat in the past 10-20 years, the TR-1 model could exceed 90,0000 ft), and the maximum speed and altitude of the SR-71 was known to exceed the official “Mach 3 at 70,000 ft.”  In fact, depending very much on the ambient temperature and density at altitude, the SR-71 could easily exceed Mach 3.5 and was capable of flying so fast it could literally tear itself apart.  Pilots had to carefully monitor sensors that told them things like inlet spike temperature, leading temperature, etc.  But when conditions were right, when the air was sufficiently cold at altitude and the bird operating just right, going over Mach 3.5 (2300 mph) was quite possible, and occurred with a fair degree of regularity.  Likewise, altitudes routinely exceeded 80,000 ft (in fact, this was pretty much SOP) while 90,000 ft was topped regularly.  And that in level flight, if an SR-71 was ever “zoomed” (not advised), with all speed they were carrying, they could have probably gone over 150,000 ft, while also likely dying for the privilege as the always temperamental “Habu” departed controlled flight at that extreme altitude.

Below are some anecdotes from an SR-71 pilot are below, via Gizmodo.  They make for fascinating reading to a geek like me.

We trained for a year, flying out of Beale AFB in California , Kadena Airbase in Okinawa, and RAF Mildenhall in England . On a typical training htvhsamqfpusm7qqi3qrmission, we would take off near Sacramento, refuel over Nevada, accelerate into Montana, obtain high Mach over Colorado, turn right over New Mexico, speed across the Los Angeles Basin, run up the West Coast, turn right at Seattle, then return to Beale. Total flight time: two hours and 40 minutes.

One day, high above Arizona , we were monitoring the radio traffic of all the mortal airplanes below us. First, a Cessna pilot asked the air traffic controllers to check his ground speed. ‘Ninety knots,’ ATC replied. A twin Bonanza soon made the same request. ‘One-twenty on the ground,’ was the reply. To our surprise, a navy F-18 came over the radio with a ground speed check. I knew exactly what he was doing. Of course, he had a ground speed indicator in his cockpit, but he wanted to let all the bug-smashers in the valley know what real speed was ‘Dusty 52, we show you at 620 on the ground,’ ATC responded. The situation was too ripe. I heard the click of Walter’s mike button in the rear seat. In his most innocent voice, Walter startled the controller by asking for a ground speed check from 81,000 feet, clearly above controlled airspace. In a cool, professional voice, the controller replied, ‘ Aspen 20, I show you at 1,982 knots on the ground.’ We did not hear another transmission on that frequency all the way to the coast. [Three things – since this was a training flight, they were almost certainly headed west when they got the ground speed reading from the ground controllers, meaning they were flying against the prevailing west-to-east jet stream to the extent it even exists at that altitude.  Jets can frequently pick up 100 kts or more ground speed by flying with the jet stream, but these guys were going against it.  Two, land-based radar estimation of ground speed is accurate to within a few knots. Three, 1982 knots means 2302 mph, or right at Mach 3.5.  And that’s against the wind.]

vypkdhe3wtk2m4sypp4j……..One moonless night, while flying a routine training mission over the Pacific, I wondered what the sky would look like from 84,000 feet if the cockpit lighting were dark. While heading home on a straight course, I slowly turned down all of the lighting, reducing the glare and revealing the night sky. Within seconds, I turned the lights back up, fearful that the jet would know and somehow punish me. But my desire to see the sky overruled my caution, I dimmed the lighting again. To my amazement, I saw a bright light outside my window. As my eyes adjusted to the view, I realized that the brilliance was the broad expanse of the Milky Way, now a gleaming stripe across the sky. Where dark spaces in the sky had usually existed, there were now dense clusters of sparkling stars Shooting stars flashed across the canvas every few seconds. It was like a fireworks display with no sound. I knew I had to get my eyes back on the instruments, and reluctantly I brought my attention back inside. To my surprise, with the cockpit lighting still off, I could see every gauge, lit by starlight. In the plane’s mirrors, I could see the eerie shine of my gold spacesuit incandescently illuminated in a celestial glow. I stole one last glance out the window. Despite our speed, we seemed still before the heavens, humbled in the radiance of a much greater power…….

…….With the Libyan coast fast approaching now, Walt asks me for the third time, if I think the jet will get to the speed and altitude we want in time. I tell him yes. I know he is concerned. He is dealing with the data; that’s what engineers do, and I am glad he is. But I have my hands on the stick and throttles and can feel the heart of a thoroughbred, running now with the power and perfection she was designed to possess. I also talk to her. Like the

Ol' 960

Ol’ 960

combat veteran she is, the jet senses the target area and seems to prepare herself.

For the first time in two days, the inlet door closes flush and all vibration is gone. We’ve become so used to the constant buzzing that the jet sounds quiet now in comparison. The Mach correspondingly increases slightly and the jet is flying in that confidently smooth and steady style we have so often seen at these speeds. We reach our target altitude and speed, with five miles to spare. Entering the target area, in response to the jet’s new-found vitality, Walt says, ‘That’s amazing’ and with my left hand pushing two throttles farther forward, I think to myself that there is much they don’t teach in engineering school.

Out my left window, Libya looks like one huge sandbox. A featureless brown terrain stretches all the way to the horizon. There is no sign of any activity. Then Walt tells me that he is getting lots of electronic signals, and they are not the friendly kind. The jet is performing perfectly now, flying better than she has in weeks. She seems to know where she is. She likes the high Mach, as we penetrate deeper into Libyan airspace. Leaving the footprint of our sonic boom across Benghazi , I sit motionless, with stilled hands on throttles and the pitch control, my eyes glued to the gauges.

Only the Mach indicator is moving, steadily increasing in hundredths, in a rhythmic consistency similar to the long distance runner who has caught his second wind and picked up the pace. The jet was made for this kind of performance and she wasn’t about to let an errant inlet door make her miss rf3z44d552foerwoguixthe show. With the power of forty locomotives, we puncture the quiet African sky and continue farther south across a bleak landscape.

Walt continues to update me with numerous reactions he sees on the DEF panel. He is receiving missile tracking signals. With each mile we traverse, every two seconds, I become more uncomfortable driving deeper into this barren and hostile land. I am glad the DEF panel is not in the front seat. It would be a big distraction now, seeing the lights flashing. In contrast, my cockpit is ‘quiet’ as the jet purrs and relishes her new-found strength, continuing to slowly accelerate.

The spikes are full aft now, tucked twenty-six inches deep into the nacelles. With all inlet doors tightly shut, at 3.24 Mach, the J-58s are more like ramjets now, gulping 100,000 cubic feet of air per second. We are a roaring express now, and as we roll through the enemy’s backyard, I hope our speed continues to defeat the missile radars below. We are approaching a turn, and this is good. It will only make it more difficult for any launched missile to solve the solution for hitting our aircraft.

I push the speed up at Walt’s request. The jet does not skip a beat, nothing fluctuates, and the cameras have a rock steady platform. Walt received missile launch signals. Before he can say anything else, my left hand instinctively moves the throttles yet farther forward. My eyes are glued to temperature gauges now, as I know the jet will willingly go to speeds that can harm her. The temps are relatively cool and from all the warm temps we’ve encountered thus far, this surprises me but then, it really doesn’t surprise me. Mach 3.31 and Walt is quiet for the moment.

Yes, the pilots had to wear full pressure suits, like astronauts, and the suit saved at least one pilot's life

Yes, the pilots had to wear full pressure suits, like astronauts, and the suit saved at least one pilot’s life

I move my gloved finder across the small silver wheel on the autopilot panel which controls the aircraft’s pitch. With the deft feel known to Swiss watchmakers, surgeons, and ‘dinosaurs’ (old- time pilots who not only fly an airplane but ‘feel it’), I rotate the pitch wheel somewhere between one-sixteenth and one-eighth inch location, a position which yields the 500-foot-per-minute climb I desire. The jet raises her nose one-sixth of a degree and knows, I’ll push her higher as she goes faster. The Mach continues to rise, but during this segment of our route, I am in no mood to pull throttles back.

Walt’s voice pierces the quiet of my cockpit with the news of more missile launch signals. The gravity of Walter’s voice tells me that he believes the signals to be a more valid threat than the others. Within seconds he tells me to ‘push it up’ and I firmly press both throttles against their stops. For the next few seconds, I will let the jet go as fast as she wants. A final turn is coming up and we both know that if we can hit that turn at this speed, we most likely will defeat any missiles. We are not there yet, though, and I’m wondering if Walt will call for a defensive turn off our course.

With no words spoken, I sense Walter is thinking in concert with me about maintaining our programmed course. To keep from worrying, I glance outside, wondering if I’ll be able to visually pick up a missile aimed at us. Odd are the thoughts that wander through one’s mind in times like these. I found myself recalling the words of former SR-71 pilots who were fired upon while flying missions over North Vietnam They said the few errant missile detonations they were able to observe from the cockpit looked like implosions rather than explosions. This was due to the great speed at which the jet was hurling away from the exploding missile.

960 with an afterburner blowout.  This could be very dangerous due to the asymmetric thrust.

960 with an afterburner blowout. This could be very dangerous due to the asymmetric thrust.

I see nothing outside except the endless expanse of a steel blue sky and the broad patch of tan earth far below. I have only had my eyes out of the cockpit for seconds, but it seems like many minutes since I have last checked the gauges inside. Returning my attention inward, I glance first at the miles counter telling me how many more to go, until we can start our turn Then I note the Mach, and passing beyond 3.45, I realize that Walter and I have attained new personal records. The Mach continues to increase. The ride is incredibly smooth. [This baby was born to run.  This is aircraft 61-7960, which is the aircraft in most of the photos]

There seems to be a confirmed trust now, between me and the jet; she will not hesitate to deliver whatever speed we need, and I can count on no problems with the inlets. Walt and I are ultimately depending on the jet now – more so than normal – and she seems to know it. The cooler outside temperatures have awakened the spirit born into her years ago, when men dedicated to excellence took the time npbhhpcrxqb0fnc1cx2iand care to build her well. With spikes and doors as tight as they can get, we are racing against the time it could take a missile to reach our altitude.

It is a race this jet will not let us lose. The Mach eases to 3.5 as we crest 80,000 feet. We are a bullet now – except faster. We hit the turn, and I feel some relief as our nose swings away from a country we have seen quite enough of. Screaming past Tripoli , our phenomenal speed continues to rise, and the screaming Sled pummels the enemy one more time, laying down a parting sonic boom. In seconds, we can see nothing but the expansive blue of the Mediterranean . I realize that I still have my left hand full-forward and we’re continuing to rocket along in maximum afterburner.

The TDI now shows us Mach numbers, not only new to our experience but flat out scary. Walt says the DEF panel is now quiet, and I know it is time to reduce our incredible speed. I pull the throttles to the min ‘burner range and the jet still doesn’t want to slow down. Normally the Mach would be affected immediately, when making such a large throttle movement, but for just a few moments old 960 just sat out there at the high Mach, she seemed to love and like the proud Sled she was, only began to slow when we were well out of danger.

I loved that jet.

———–End Quote———–

Now that’s a story.

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The sad fate of 960:

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Comments

1. Tradical - February 13, 2015

I worked for a defense contractor when the SR was retired. In our library we had a ‘retirement’ vhs that was worth the watch.

What an piece of engineering and art!

2. ForThoseILove - February 13, 2015

Reblogged this on 4ThoseILove.

3. H-town - February 14, 2015

Badass

4. Marc - February 14, 2015

Despite the fact that I work for a competitor of Lockheed, I still think that is an awesome machine. The “-B” is on display at the Kalamazoo MI AIR ZOO and my oldest boy is fascinated by it. He can’t wait to see it again!


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