On the fourth day, we get “calling” birds. Turns out, much like the pear tree, this is another misunderstood lyric. The original is talking about colly birds (or collie) which means black. It originates from coal mines so to say something is “coaly” is to say “black“.
Now, there are 31 different species of blackbirds, so I’ll just reach in and pick one at random. Ah yes, here we are… the Lockheed SR-71 Blackbird.
That’s a super-sonic jet. In fact, it’s the world’s fastest and highest flying plane. Way more interesting than most blackbirds. The plane was build for the US military in 1964. It was originally intended as a fighter jet, but they had a serious problem; the Blackbird can literally fly faster than a speeding bullet. It would have just shot itself. However, being able to out-run a missile is an excellent defensive strategy.
The plane can exceed Mach 3, or three times the speed of sound. That’s over 3219 kilometres per hour. It flew from New York to London in less than 2 hours. (The Concorde passenger jet takes about 3 hours at Mach 2)
Travelling that fast brings along some technical trouble. Between the massive engines and the simple friction against the air, the Blackbird would get very hot. We’re talking 1200 degrees Fahrenheit hot. When flying at full speed, the tail end of the plane would glow red hot. With the heat expansion of all the titanium parts, the SR-71 grew an extra foot in length when in flight.
Now, with all this advanced technology, would you believe that the Blackbird leaked fuel terribly. Just sitting on the runway, it would drip about 16 gallons each hour onto the ground. Oddly, this was done on purpose. When sitting around, the fuel tank had holes and gaps in it that allowed the fuel to drip. This goes back to the incredible heat generated from flight. Once it was moving at high speeds all the metal expands, including the fuel tanks, and those gaps are closed right up.
The SR-71 Blackbird served as a very successful reconnaissance plane for the US military from its introduction in 1964 until the program was closed in 1990. These planes were very expensive to run, requiring 450 hours of maintenance and repairs for every 1 hour of flight time. However, three Blackbirds are still being used by NASA for research of high-altitude flight. If it’s not too full of fuel, the Blackbird can actually get into space, at 100,000 feet.
- Source: the SR-71 Blackbird