The Apollo missions to the Moon weren’t the pinnacle of human engineering… the design of the Lockheed Martin SR-71 Blackbird, was. Sure, Apollo might be the pinnacle of human triumph, but as far as engineering went, it wasn’t nearly as difficult as other projects being worked on at the same time. Landing on the Moon was a massive engineering challenge, but most of the engineering was to build a craft as light as possible and use minimal resources to accomplish the task. It didn’t have to handle the sort of intense dynamics that the SR-71 needed to handle.
For me, the SR-71 Blackbird is sex. I look at that beauty, nicknamed ‘the sled’, and begin to drool. As an Aerospace Engineering student and member of the Air Force… it could be dangerous to leave me near one, alone. Most people who don’t fully understand that masterpiece can’t and won’t be able to appreciate it for what it’s worth.
Oh boy, where do I start with this gem. The Blackbird was the first aircraft to be mostly made of titanium, over 80%, actually. This alone was incredible because of the rarity and cost for such a large amount of titanium. Ironically, it was covertly obtained from the USSR… which I liken to a way for us to say, ”gotcha!”. Later, many of the hours of flight would involve constant reconnaissance over Russia.
This titanium was used because it was light, strong and very heat resistant. Because the aircraft was to be designed to fly at speeds greater than Mach 3, three times faster than the speed of sound (761 mph at sea level), the very impact of air on the Blackbird was going to cause the surface to reach temperatures close to 2,000 degrees F. In fact, the intense heat to be encountered while flying caused the Blackbird to expand several inches. So the complete jet, from nose to tail had to be designed so that all parts would fit very loosely together so that when it expanded, everything would tighten up and nothing would crack. JP-7 jet fuel would actual leak all over the taxiway and runway until the sled got up to speed, and once it did, it would slow down because it would need to refuel in-flight after leaking so much. Also, a lot of the surfaces on the SR-71 aren’t smooth, they are actually corrugated so that when there was expansion, there would be no compromise of structural integrity.
Now, onto the jet engines. There were 2 on the SR-71 Blackbird, but technically, there were 4… why? Well, that’s because they were essentially the first Ramjet ever made and they stuck a Turbojet inside the ramjet. It was a hybrid. Ramjets only work at very high speeds because it involves extreme compression and ignition of fast moving air. The spike you see on the front of the J58 engines was actually the beginning of the ramjet and the turbojet was tucked inside. The turbojet would run the aircraft at sub-sonic speeds, but once it got up to speed, the majority of power would be from the ramjet. Flaps would seal inside the engine to initiate the ramjet and the intense vibration in the cockpit would deftly seize and it was almost as if she was gliding… just at Mach 3+.
The cone on the front of the aircraft was also maneuverable. It would retract as the speed increased so that it could utilize the sonic shockwave on the front of the Blackbird to aid in thrusting the engine when the ramjet was being utilized. Essentially, the J58 engines had no top speed. The speed was limited to the heat expansion of the aircraft. You’ll read stories later about pilots constantly pushing the envelope past the “max” speed in order to outrun enemy missiles.
The JP7 jet fuel had to be redesigned for this aircraft because it had to operate at extremely high altitude and high velocity. So the engine would need an assist to start or ignite the afterburner. The only way to do this was with triethylborane, TEB. It was extremely dangerous but did the job. Not only did it have this assisted chemical start, but the SR-71 utilized 2 V8 engines to start each jet when sitting on the tarmac.
So, all of the above are just a few things of the many that were practically invented to use on this aircraft. Everything worked in perfect harmony, never to be matched again… even 60 years later. The service ceiling was well above 80,000 ft and flights were recorded at over Mach 3.5, even when the max speed was said to be Mach3.2. She had early stealth capability, even though it wasn’t needed thanks to her unmatchable altitude and speed. How can the enemy catch this… not to mention it’s uncanny ability to take high quality photos at that speed and altitude…
The SR-71 Blackbird flew from Los Angeles to Washington DC in slightly over 60 minutes. That’s 2,300 miles, which means the Blackbird had an AVERAGE speed of 2,300 mph!!! She could fly 1 mile in just over 1 second, HOLY COW!!!
Only 93 pilots have ever been in control of the sled, which is fewer than those who have piloted the Space Shuttle. “On a typical training mission, 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” (Brian Shul, Pilot).
Brian Shul, sled pilot, also recalls a rather hilarious story in his book, Sled Driver: Flying the World’s Fastest Jet… “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.”
“In another famous SR-71 story, Los Angeles Center reported receiving a request for clearance to FL 60 (60,000 ft). The incredulous controller, with some disdain in his voice, asked “How do you plan to get up to 60,000 feet? The pilot (obviously a sled driver), responded, “We don’t plan to go up to it, we plan to go down to it.” He was cleared…”
Now, my word count is well over 1200, yet I could keep going. There might be more posts in the future that detail exact specifics of the aircraft, but this is a brief overview. The SR-71 Blackbird is an absolute engineering masterpiece, the best one in my opinion. Would I kill someone to fly it, my morals would say no but it’s an interesting thought. I don’t think I’d be cleared to fly her anyway, seeings how my only experience is in propeller driven craft… as apposed to ‘faster than bullet speed’ ramjet thrust.
If you want to read a segment out of his book, since it’s rare and $600, check out this bit, it’s incredibly entertaining and aw-inspiring… http://www.freerepublic.com/focus/f-vetscor/1981814/posts
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- SR-71 Blackbird Communication to Tower (econrates.com)
