Manhole Covers in Space

Strange Horizons ^ | 6/27/2009 | By Debbie Moorhouse

[SES1066]

OK, who wants to be the proposer of this to the Discover Channel’s Mythbuster Show? I wonder what kind of clearance and site would be needed for this one? Guarantee that the police explosives range ain’t going to cut this mustard!

[Dusty Road]

LOL that's what I was thinking it could be miles away. I know I can use a Number 5 Green bag charge behind a 212 lb 8 inch projectile and land it about 22 miles away.

[Dusty Road]

And that's at 1850 fps, nowhere near the velocities they're claiming would be behind the plate. Considering the aerodynamics’s of a flat steel plate weighing 3000 pounds going at unimaginable velocity's I suspect it immediately crumpled into a rather taco type shape and landed somewhere within 50 to 100 miles of the initial site. Somewhere out in the Nevada Desert is a 3000 lb taco shell. That's if it wasn't completely destroyed by the intense caused by the velocity vrs resistance and the intense heat of the blast itself.

[Bender2]

Bump for me to search for a story I heard about three steel balls being fired into orbit from a WAC Corporal on top of a captured V-2 to create an experimental two-stage research rocket. Eight of these vehicles, known as RTV-G-4 Bumper, were used for tests between 1948 and 1950.

BTW as I have had lots of strange love over the years... could sonof possibly be mine????

[SampleMan]

Its true. I saw the stills several years ago along with the high speed photography timer. Extrapolation showed that the manhole cover achieved escape velocity.

The cover was on top of an air shaft and was propelled by the compressed air from the blast.

[reagan_fanatic]

If a manhole cover falls in the desert, does it make a sound?

[big'ol_freeper]

Might have well been blasted into space, you won't find any of these in the possession of GOP members of Congress.

[TXnMA]

I agree that the metal plate could not have reached 6X escape velocity -- based on available energy input..

Even so, the plate's maximum velocity would have been at "launch" -- in the densest part of the atmosphere. IOW, it would have been a "meteor in reverse", and would have vaporized before it exited the atmosphere...

[UCANSEE2]

But I would also expect a hurtling disc would have rapidly begun to fly like a Frisbee, and that would ease its passage through the air.

The chance that this 'disc' would maintain a completely 'flat', or 'face on' trajectory, is zero.

[Tijeras_Slim]

If it came down somebody would have reported it.

Even today there's a whole lotta nothing out there.

[UCANSEE2]

You do know they didn’t fire this manhole cover into space, just yesterday?

How many of those seismic stations were in place the day this nuclear cannon was fired?

[UCANSEE2]

Extrapolation showed that the manhole cover achieved escape velocity.

Extrapolation ... isn't that what got us the current Global Warming Theory???

[SampleMan]

Extrapolation ... isn't that what got us the current Global Warming Theory???

I think that was more "Invention" than extrapolation. In any event the physics of extrapolating velocity from known data points is very exact in this case.

[houeto]

I just KNEW this would be one of your posts! I was wrong.

[Pan_Yan]

[JoeProBono]

SORRY!!

[SevenofNine]

Can we arranged Maury Povitch do DNA test on you Bender and him

[just a dude]

At low speeds, a plasma forming around the object would reduce its drag coefficient. Simple fluid mechanics don't apply anymore.

But:

H. Julian Allen and A. J. Eggers, Jr. of the National Advisory Committee for Aeronautics (NACA) made the counterintuitive discovery in 1951 that a blunt shape (high drag) made the most effective heat shield. From simple engineering principles, Allen and Eggers showed that the heat load experienced by an entry vehicle was inversely proportional to the drag coefficient, i.e. the greater the drag, the less the heat load. Through making the reentry vehicle blunt, air can't "get out of the way" quickly enough, and acts as an air cushion to push the shock wave and heated shock layer forward (away from the vehicle). Since most of the hot gases are no longer in direct contact with the vehicle, the heat energy would stay in the shocked gas and simply move around the vehicle to later dissipate into the atmosphere.

An initial velocity of 67,000 m/s generates about the same temperature in Kelvin, 67,000K. But this is a peak shock layer temperature. That's on the leading side. If the object is tumbling or not, then the alee side is subjected to very low pressures which effectively freeze chemical reactions. Thus cooling the object...

Given the initial impact from the nuclear soup emerging from the shaft, the disk would probably be deformed into a conical/dome shape...

In 1 or 2 seconds there wouldn't be enough time for anything to happen, other than slamming into Leary's orbiting head. But then again it wasn't up there at the time - lol

Interesting stuff to think about.

[UCANSEE2]

In any event the physics of extrapolating velocity from known data points is very exact in this case.

OK. Exactly how fast was it going, and how far did it go?

[SampleMan]

OK. Exactly how fast was it going, and how far did it go?

Initial speed was ~ 25,000 mph, and it is still flying through space. It did not go into orbit, it left the Earth's gravitational field.