On this day in 1947 a Bell X-1 experimental rocket plane exceeded the speed of sound in level flight. Contrary to the legend it wasn’t the first time a plane had gone that fast, nor even the first time it had been done on purpose – which is not quite the same thing.
I’ve read that a P-51 Mustang and some other propeller-driven fighter planes could exceed the speed of sound in a powered dive, but very bad things tended to happen when they did. After WWII, of course, prop warplanes were all obsolete and designers looked to a time when speeds in excess of what conventional airframes could withstand would become routine. The trouble is, they couldn’t design new planes that could take advantage of the available speed because nobody knew for sure what caused those bad things. And that was where the X-1 came in.
It was very small and light – its loaded weight consisted mostly of fuel, which it expended with a wild abandon that would make Al Gore cry. And only one thing about its fuselage design wasn’t a wild-ass guess…
Nobody knew for sure why the most modern aircraft of the period lost stability at speeds in excess of 650 mph. But everybody knew that a .50 BMG bullet remained stable at speeds far in excess of it. And that was the reason for the X-1’s peculiar shape: The designers took advantage of the one thing they knew.
And then some idiot got in, dropped out the bottom of a perfectly good B-29, lit four half-tested little rocket motors, and became very, very famous.
Again contrary to the movie, it wasn’t like Chuck Yeager saw this thing sitting around untended in the desert and casually decided to break the sound barrier with it. The famous flight was the plane’s fiftieth, and that was after a whole lot of tinkering with control surfaces – because it turned out the stability problem didn’t have anything to do with fuselage shape at all.
And now, over half a century later, you still (with very few exceptions) need to either be in the military or be an astronaut if you wish to have your soft body exceed the speed of sound.
Yup. ‘Cause the whole point of the aerospace industry is to a: make cool gadgets for killing people and breaking things, and b: keep the inventory from fleeing the warehouse.
. . . and c: make lotsa money for gummint contractors.
So, what did the stability problem have to do with?
I know, two yearsish late and all, but the stability or lack thereof was due to the pressure wave formed as the aircraft pierced the sound barrier, and all the little waves expressed by every surface of the aircraft interacting and secret science crap like that. If they had left the wings and tail off, then there would have been no interference except from the nose.
So, one way to defeat the shockwaves is to induce the shockwaves further ahead of the aircraft. This is why supersonic aircraft have pointy things on their noses – moves the shockwave further in front of the plane.
Swept wings helps too. F-14 and F-111 swingwings were designed to have pretty straightish wings for low speed travel and raked wings for superdupersonic.
And, yeah the overall surface area of the plane in cross-section from nose to tail does affect the performance of the object going through the air. Thus the dreaded coke-bottle aircraft, where the waist is pinched or reduced to make up the cross-sectional surface area of the wings, engines and dangly stuff.
Such a nerd. Such a nerd
And I was a scribe for a letter-bomb task force where the stamp used was a commemorative X-1 stamp, and some ATF dude called it a ‘bomber’. Stupid me opened my mouth and corrected said Federale. Between that and asking the feminazi Captain in charge of the investigation who the ‘chariman’ was (THAT’S CHAIRPERSON!!) almost got me fired….