Re: OT interesting find

On Nov 28, 12:21 pm, Ad absurdum per aspera <jtch...@xxxxxxxxx> wrote:
OTOH they aren't a serious challenge to the absolute land speed record
of Mach 8.5.http://en.wikipedia.org/wiki/Land_speed_record_for_railed_vehicles
Your link says unmanned! well Mach 50 is easy.

Actually, barring some calculations that would give me a headache on a
nice Saturday morning, I guess that Mach 50 is ludicrous per se for
propelling a macroscopic object through any reasonable value of
"atmosphere." Orbital re-entry occurs at about half that (and of
course the spacecraft must be heat-shielded in one way or
another). Light-gas guns can be used to simulate astronomical
impacts (e.g., meteorite impact cratering, debris encountered in
orbit, etc.) but I think the barrel and target chamber are usually
pumped down to at least rough vacuum.

Yes.
Joe, I think you'll get a laff out of this link
(cycle down to Pascal B, see 53 km/sec),

http://nuclearweaponarchive.org/Usa/Tests/Plumbob.html

((Lauel and Hardy test an A-bomb:-)), that was what I was thinking,
when I wrote 'Mach 50'.

Pondering the Space Shuttle's mission profiles -- "max Q" on the way
up and braking on the way down -- gives some interesting insight into
speed, altitude, pressure, etc. So does what happens when meteors of
various sizes and speeds enter the atmosphere (e.g.,http://tinyurl.com/meteorspeed).

The unmanned rocket-sled test at Holloman was quite an engineering
feat in its own right, as detailed onhttp://www.rdecom.army.mil/rdemagazine/200401/itl_amrdec_roadrunner.html
(executive summary: this wasn't even your ordinary rocket-sled track,
let alone your ordinary train.)

As for Stapp's rocket sled work, the point was not how fast he was
going but how quickly he stopped (with a side interest in what happens
when you step outside at slightly supersonic speeds). I mean no
deprecation of him whatsoever -- from everything I've read, his
aeromedical science was pioneering, influential, and above-and-beyond
brave -- but neither sheer speed nor manned control of the vehicle was
the main issue.

Moving an F104 at 800 mph at 4 ' altitude, should probably be
done 1st with an FBW inertial guidance system to keep on or near
the ball (surface of earth), remotely controlled then, with
confidence,
put a humanoid in it.
Greater minds prevail, but I think human reaction times of 0.4 secs
might be a bit slow compared to a FBW needed in that test.

Cheers,
--Joe

Cheers back to ya.
Ken
.

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