The 41-year-old Lockheed Blackbird is still the fastest aircraft ever built, and nothing out there today is even close to catching it.

The Lockheed SR-71 Blackbird reconnaissance plane (aka The Sled or Habu -Japanese name given by the locals in Okinawa for its similarity to a viper-) still holds until today, the world speed record for a fixed-wing aircraft.

That occurred back on the 28th of July 1976 as Capt. Robert Helt broke the altitude record in straight and level flight at 85,069 feet (25,929 mts. or 16.1 miles up) and set the speed at 1,906 knots or 3.3 Mach (2,193 mph or 3,529 km/h). Other pilots said they hit speeds of 3.6 Mach and touched altitudes of 100,000 feet, but Helt would hold the official numbers (astronauts, by the way, can only get their wings at 264,000 feet (80,467 mts. or 50 miles up). Lockheed had to set the limits between 3.3 and 3.5 Mach, after that they were concerned it could break apart or start to melt. The external surfaces would be exposed to temperatures of 260 °C , the exterior quartz windscreens would be subjected to temperatures of 316 °C during missions (the interior part of the windows registered 120 °C).  

The SR-71 structure was 85% Titanium, the rest were materials that at the time were unheard of “reinforced polymer carbon fibres”, components that nowadays have replaced between 60-80% of what would have been the aluminium used on the B787’s or A350’s. Only 32 were ever made.

At secretive Skunkworks (the Lockheed and Lockheed Martin Advanced Development Projects group in Palmdale, California) the engineers majour apprehension was how to confront the high temperatures the aircraft would be submitted to, for the laws of aerodynamics and thermodynamics changed dramatically at such altitudes and speeds. In the end, the skin of the aircraft would be corrugated (in order for it to expand as speeds and temperatures were heightened, concurrently increasing its resistance). After fuelling the SR-71 for flight, it was common and somewhat intimidating to see how the aircraft would bleed JP-7 fuel from just about every joint onto the floor below itself, it was a most unwelcoming and threatening sight for anyone close to the aircraft, let alone the concerns of the pilot strapped into it. This subtle rainfall of flammable fluids was inevitable for the panels of the aircraft and the fuel sealing systems had to be loosely fit so that they could expand (and fit in place) later in flight as the aircraft heated up as it reached speeds 3 times the speed of sound.     

The SR-71 flew unarmed other than with a set of cameras, because no missiles could reach her, nor could any other aircraft catch up with her whilst blasting at Mach 3, it was only vulnerable during take off’s and landings, which were never close to where the missions took her (Vietnam, Laos, Cambodia, Korea, Libya, Egypt, Cuba - overflying Cuba was a couple of minutes -, Iraq amongst others, and yes, the USSR -even if this was never fully recognised-). The logistical support to keep an SR-71 operative was daunting, it constantly needed airborne refuelling and very specialised technical support on the ground, it was common for the Habu’s to return from missions with rivets missing, bended panels, deformed air intakes, and turnarounds for single aircraft could take months. It was hard to calculate an operating cost of an SR-71 (depending on the support needed: aerial refuelling, specialised ground support, spares, ad-hoc communications centres, etc.) numbers vary from 37 to 50 thousand USD (1970’s dollars) per hour of flight.

Operational capabilities came to a close at the end of 1989. The squadron would remain in place until the mid-90’s on operational stand-by, but in the end, the advances in satellite imaging would eventually ground and then kill the Blackbird. NASA would pick up a few for research purposes, but the Habu’s glory days were over.

The recollection of events that Major Shul shares during a routine training flight belting over the Arizona–California lower stratosphere are far more entertaining than what I have written above. This story has been around for quite some time now, it is very well written and you can even flavour the moment, it’s worth sharing again, enjoy. M

The King of Speed by Major USAF (r) Brian Shul

There were a lot of things we couldn't do in an SR-71, but we were the fastest guys on the block and loved reminding our fellow aviators of this fact. People often asked us if, because of this fact, it was fun to fly the jet. Fun would not be the first word I would use to describe flying this plane. Intense, maybe. Even cerebral. But there was one day in our Sled experience when we would have to say that it was pure fun to be the fastest guys out there, at least for a moment.

It occurred when Walt and I were flying our final training sortie. We needed 100 hours in the jet to complete our training and attain Mission Ready status. Somewhere over Colorado we had passed the century mark. We had made the turn in Arizona and the jet was performing flawlessly.

My gauges were wired in the front seat and we were starting to feel pretty good about ourselves, not only because we would soon be flying real missions but because we had gained a great deal of confidence in the plane in the past ten months. Ripping across the barren deserts 80,000 feet below us, I could already see the coast of California from the Arizona border. I was, finally, after many humbling months of simulators and study, ahead of the jet.

I was beginning to feel a bit sorry for Walter in the back seat. There he was, with no really good view of the incredible sights before us, tasked with monitoring four different radios. This was good practice for him for when we began flying real missions, when a priority transmission from headquarters could be vital. It had been difficult, too, for me to relinquish control of the radios, as during my entire flying career I had controlled my own transmissions. But it was part of the division of duties in this plane and I had adjusted to it. I still insisted on talking on the radio while we were on the ground, however. Walt was so good at many things, but he couldn't match my expertise at sounding smooth on the radios, a skill that had been honed sharply with years in fighter squadrons where the slightest radio miscue was grounds for beheading. He understood that and allowed me that luxury. Just to get a sense of what Walt had to contend with, I pulled the radio toggle switches and monitored the frequencies along with him. The predominant radio chatter was from Los Angeles Centre, far below us, controlling daily traffic in their sector. While they had us on their scope (albeit briefly), we were in uncontrolled airspace and normally would not talk to them unless we needed to descend into their airspace.

We listened as the shaky voice of a lone Cessna pilot asked Centre for a readout of his ground speed.

Centre replied: "November Charlie 175, I'm showing you at ninety knots on the ground."

Now the thing to understand about Centre controllers, was that whether they were talking to a rookie pilot in a Cessna, or to Air Force One, they always spoke in the exact same, calm, deep, professional, tone that made one feel important. I referred to it as the "Houston Centre Voice." I have always felt that after years of seeing documentaries on this country's space program and listening to the calm and distinct voice of the Houston Centre Controllers, that all other controllers since then wanted to sound like that... and that they basically did. And it didn't matter what sector of the country we would be flying in, it always seemed like the same guy was talking. Over the years that tone of voice had become somewhat of a comforting sound to pilots everywhere. Conversely, over the years, pilots always wanted to ensure that, when transmitting, they sounded like Chuck Yeager, or at least like John Wayne. Better to die than sound bad on the radios.

Just moments after the Cessna's inquiry, a Twin Beech piped up on frequency, in a rather superior tone, asking for his ground speed.

 "Ahhhh, Twin Beach: I have you at one hundred and twenty-five knots of ground speed."

Boy, I thought, the Beechcraft really must think he is dazzling his Cessna brethren.

Then out of the blue, a Navy F-18 pilot out of NAS Lemoore came up on frequency. You knew right away it was a Navy jock because he sounded very cool on the radios.

"Centre, Dusty 52 ground speed check."

Before Centre could reply, I'm thinking to myself, hey, Dusty 52 has a ground speed indicator in that million-dollar cockpit, so why is he asking Centre for a readout ? Then I got it ----- ol' Dusty here is making sure that every bug smasher from Mount Whitney to the Mojave knows what true speed is. He's the fastest dude in the valley today, and he just wants everyone to know how much fun he is having in his new Hornet.

And the reply, always with that same, calm, voice, with more distinct alliteration than emotion:

"Dusty 52, Centre, we have you at 620 on the ground."

And I thought to myself, is this a ripe situation, or what? As my hand instinctively reached for the mic button, I had to remind myself that Walt was in control of the radios. Still, I thought, it must be done -- in mere seconds we'll be out of the sector and the opportunity will be lost. That Hornet must die, and die now.

I thought about all of our Sim training and how important it was that we developed well as a crew and knew that to jump in on the radios now would destroy the integrity of all that we had worked toward becoming. I was torn. Somewhere, 13 miles above Arizona, there was a pilot screaming inside his space helmet.

Then, I heard it. The click of the mic button from the back seat. That was the very moment that I knew Walter and I had become a crew. Very professionally, and with no emotion, Walter spoke:

"Los Angeles Centre, Aspen 20, can you give us a ground speed check?"

There was no hesitation, and the reply came as if was an everyday request:

"Aspen 20, I show you at one thousand eight hundred and forty-two knots, across the ground."

I think it was the forty-two knots that I liked the best, so accurate and proud was Centre to deliver that information without hesitation, and you just knew he was smiling. But the precise point at which I knew that Walt and I were going to be really good friends for a long time was when he keyed the mic once again to say, in his most fighter-pilot-like voice:

 "Ah, Centre, much thanks. We're showing closer to nineteen hundred on the money."

For a moment, Walter was a God. And we finally heard a little crack in the armor of the Houston Centre Voice, when L.A. came back with

"Roger that Aspen, your equipment is probably more accurate than ours. You boys have a good one."

It all had lasted for just moments, but in that short, memorable sprint across the southwest, the Navy had been flamed, all mortal airplanes on freq were forced to bow before the King of Speed, and more importantly, Walter and I had crossed the threshold of being a crew. A fine day's work.

We never heard another transmission on that frequency all the way to the coast. For just one day, it truly was fun being the fastest guys out there.