[Mariner]

1.0 is a BC equivalent of a bullet in free space.
it does not slow down in one mile. or 1,000 miles.

of course, 1.0 is not the BC of the glider.

But .8 is not out of the realm of plausibility. Long, heavy and precisely machined. In the thin stratosphere it can be hypersonic for quite a distance.

Put that in your ballistic calculator and let us know the precise result?

[Magnum44]

I think your definition is not consistent with the folks at Hornady. I see one calculator that lets you go to BC 1.2, though again, I have never seen anything I am reloading at better than .6 or .7

From Wiki:

Almost all rounds have a ballistic coefficient of less than 1.0, but large rounds like the 50 BMG can exceed this normal BC. The higher the number, the less drag the projectile will experience. But a higher ballistic coefficient doesn't necessarily mean it is a better bullet.

My point was that even using highly optimistic numbers, a glider is not much value as a missile.

Please feel free to do your own homework and post. I am not here to be the answer guy to everyones questions.

[Kevmo]

The trick is to make it long, thin, and have control of the boundary layer.

100 years ago, Oscar Schrenk and Ludwig Prandtl showed that supersonic control of the boundary layer would yield 8x increase in lift coefficient.

To put it in terms of velocity:
The drag due to uncontrolled turbulent layer viscosity boundary layer in supersonic (let alone hypersonic) craft went up with the CUBE of velocity.

You wanna increase 2X velocity? You need 2^3 more power to overcome drag. You want 3x, you need (3x)^3 which is 27X more power to overcome drag. You want 4X velocity, —> (4X)^3 is 64X more power to overcome the drag.

Folks started talkin’ about a “sound barrier”.

The trick was to control the boundary layer so that not so much drag builds up, in such a way that (2x)^3 was more like 2.5X more power, and 3X ^3 was more like 3.8 X more power, and (4x)^3 was more like 5.5X more power. Eminently doable in 1945 Boundary Layer Control technology.

It was germans who focused on suction for boundary layer control in the 1920’s and 1930’s. They almost came to fruition by the end of the war but.... the Allies won the war.

2 years later you see Suction Boundary Layer Control experimental aircraft all over US air bases across the nation. Some of them even crash.