Andrew M emailed me with a strange factoid.
Apparently a Nimitz-class aircraft carrier weighs about 102,000 tons and generally cruises using about 260,000 horsepower. Horsepower is a difficult thing to measure when you’re talking about a nuclear reactor that’s pushing a bunch of turbines and rotating several (4) propeller shafts. No matter how you slice it, though, that’s a hell of a lot of horsepower and it’s pushing a lot of tonnage and about 6,000 people and food and water and ass-kicking stuff at a fairly high speed.
Apparently each of the engines of an SR-71 outputs about 160,000 horsepower. So the SR-71, during a speed run, is putting out more horsepower than a Nimitz-class aircraft carrier.
As Andrew observed, “pushing things through air gets difficult as your speed goes up.
I still believe that the Saturn V’s F-1 engines are the king of horsepower – a bit more than 3,000,000 horsepower each and the rocket had 5. It was also bigger and faster than an SR-71. So, there’s that. I wonder if an F-1 engine could get a Nimitz-class aircraft carrier to water-plane? Briefly. I believe I read somewhere that you could water-ski behind an aircraft carrier; they are ridiculously fast for something that big.
Time is a factor to consider. As Andrew pointed out, an SR-71 needs to refuel frequently, but a Nimitz-class aircraft carrier’s fuel supply is rated at 90 years. And let’s not talk about the F-1, the great gas-guzzler.
And, just in case you haven’t heard this story before, it’s a tale of SR-71 awesomeness.
A Boeing 747 at cruise speed is loafing along on 19,000hp of thrust. The in-cabin entertainment system of an SR-71 probably made more horsepower than that! If they had one, that is.
Back in 1997 when we were prepping for the V-One IPO roadshow, the investment bankers brought in a motivational speaker/speech coach for the management team. It was a horrible waste of time for all of us. The only part I remember was when the guy was talking about The Power of Marketing and Branding and said (in that tone that one uses when one is being very clever) “Do any of you know what Rolls Royce makes?”
Without opening my eyes I muttered, “Jet engines.”
Obviously he expected us to say “cars.” Memo to motivational speakers: know your audience.
I suppose SR-71s make carbon dioxide.
Remember the story about how the tooling for SR-71s was destroyed at the order of a congressman from a district where Raytheon was making satellite systems? That gets brought up now and then when someone asks “why don’t we resurrect the SR-71?!” The same can be said about the F-1 engine. But the situation is more complicated – entire manufacturing processes don’t exist in the same way, anymore. First off, nobody can weld like the welders who hand-welded the oxygen feed-pipe on the F-1. It takes a lifetime of welding to learn how to weld like that; we’d have to gestate a welding cult. The same goes for the machinists who made SR-71s. Nobody uses those methods to make things anymore because, adjusted for inflation, they’d be insanely expensive fine art. We could use modern CAD, composite ceramics, and CNC to make a new version of an SR-71 but it would behave differently. For one thing, it would probably be made of carbon/carbon like the leading edge of a space shuttle’s wing. That would be easier to form using today’s technology than to resurrect the titanium fabrication process used in the SR-71’s airframe. Synthetic diamond is cheaper than training a captive generation of fabricators. The wing-edge tiles on a shuttle cost about $250,000 apiece. So the new SR-71 would cost about half as much as an F-35. Just kidding about that last bit.
This is a pretty cool video: an SR-71 pilot does a walkthrough of the monstrous, unique, incredible engine of the blackbird.
But how did it work? If I understand correctly, it was a blend of a ramjet and a scramjet and a whole lot of inspired engineering. It must have been quite a thing for a bunch of people to sit down and design something like this using slide rules and paper blueprints.
Burt Rutan did a talk many years ago about how it is unlikely humans will bother to build anything like an SR-71 ever again. It’s just not a problem we have to try to solve anymore. He drew a chart that was sort of like the opposite of Ray Kurzweil’s “singularity” chart, arguing that we got really good at airplanes, built SR-71s, and since then the progress has all been directed toward efficiency. It’s an interesting meditation on what “good” means.
2000 knots is 2300 mph.