Can we ever fly faster than sound?

Personally, I’m skeptical that humans will ever fly faster than the speed of sound. But I have my doubts that humans can fly at all. I mean, really, our arms make terrible wings, and trying to flap that fast is sure to sprain a shoulder or two.

Lucky for me, someone wrote an article in the October 1944 issue of Popular Science taking a stance I can get on board with. Quite simply, the author says man cannot fly faster than the speed of sound. Reports to the contrary are, rather unsurprisingly, wrong. The entire Mach speed nomenclature exists merely to simplify detailing speeds which we *CAN* reach in these flying human death chambers.

Trust me – this is an article worth reading in full – either my cut and paste whack-job with commentary or the original article linked above.

Can We Ever Fly Faster Than Sound?

A seemingly impassable barrier blocks the way to higher plane speeds. Can we hurdle it? Our aviation editor gives his views.



DESPITE glowing newspaper reports, man cannot now fly at the speed of sound. In fact it is doubtful, according to the best authorities, that man has ever closely approached sonic speed (764 m.p.h, at sea level and 664 m.p.h, at 40,000 feet), let alone attain or exceed it. Speeds of over 500 m.p.h, in level flight are a serious challenge to design and power-plant engineers. Even in a terminal-velocity dive (straight down with all stops open), it is doubtful that any pilot has attained the speed of sound.

There are two reasons for our inability to hit the speed of sound with present-day aircraft: First, the lack of power; and, second, a little gadget called a Mach (pronounced mock) number. The second reason is the more important, for it is responsible for the first, and so, let’s delve into this Mach business.

It is merely for convenience that there is such a thing as a Mach number. It represents the relation of any speed to the speed of sound. For example a Mach number of .5 means that the speed so described is 50 percent of the speed of sound.

. . .

Compressibility is that point at which an object begins to make waves in the medium through which it is passing. A boat moves ahead slowly through the water, and no waves appear. It moves faster, and waves begin to stream around it, caused by the hull pushing ahead too fast for the water to part, let the hull pass, and then flow together behind it. There is a critical speed for every object, at which these waves appear.

My instinct says that compressibility is going to cause us troubles in our attempts to fly faster than the speed of sound. I don’t think we can make the nose of the plane and the leading edge of the wings “sharp” enough to cut through the air. But back to the article:

Instead of flowing smoothly around the part, the air is smacked against it with such force that waves of compressed and rarefied air in alternate bands are formed at the point of impact. When an object is traveling at the speed of sound, which is also the speed of a compression wave, it is easy to see what this can mean. It is like a football player who cuts ahead of his interference and is tackled. He keeps his feet and tries to drag the tackier along with him. This takes power. Making waves takes power, too, whether in a boat or in the parts of a plane. In fact, it takes such power that a plane can reach a point where it can not go any faster without a staggering increase in power.

. . .

It is not attaining: the speed of sound that causes trouble, but the compression waves and resulting turbulence when the air particles have to slow down again after the airfoil has passed. The air passing over the curve of the front of the airfoil starts off at great speed which almost instantly reaches sonic velocity and then runs smack into the slow-speed air in great turbulence behind the wing section. The result is a shock wave at the slow-down point.

. . .

So far, supersonic speeds are relatively unknown except in propeller tips and bullets. Bullets, of course, can fly at supersonic speeds, but only for a matter of seconds. They can stand these turbulences, because they are solid structures, perfectly streamlined, and driven by the energy of an outside and left-behind power—gunpowder in explosion. Were it not for the fact that projectiles are primarily designed for penetration rather than for velocity, their shape might indeed be altered for even more speed. In fact, false streamlined noses have been added to certain types of long-range shells to give them higher velocity and added wallop.

. . .

So far, we have very cagily ducked the main problem in connection with supersonic flying. That is the matter of control of such an aircraft. The matter of control is a mighty ticklish one at speeds where the slightest movement of any part of the whole produces fantastic pressures and loads as well as more shock waves. Flying at supersonic speeds in straight, level flight is one thing, but maneuvering at these speeds is quite another. It is possible that pressure-changing devices, such as spoilers, will have to be incorporated in the design. It may be that jet impulses will have to be utilized to nudge the aircraft onto another course with gentle pushes against the airflow. No one knows at the present time.

So even if we could figure out how to build an aircraft with the strength and structural design to allow faster-than-sound travel, it would probably be unpossible to steer.

Oh, and one more thing:

The writer asked one authority what would be the effect on the human body of bailing out at supersonic speeds. The written reply was the one word “AWFUL!” underlined several times.

That’s right. Don’t even think of jumping out of a plane if we do ever figure this faster-than-sound travel in the future. It would probably detroyify you in a gajillion tiny pieces and blastinize your parts all over the world.

[tags]Faster-than-sound flight, Flying, Modern Mechanix[/tags]