From: Mary Shafer <firstname.lastname@example.org>
Subject: Re: F-86, first thru sound barrier.
Date: 15 Oct 1998 10:19:10 -0700
Al Bowers <email@example.com> writes:
> Mary Shafer <firstname.lastname@example.org> writes:
> > S Erik Lindberg <email@example.com> writes:
> > > IMHO, the Budweiser rocket team's claim of having
> > > reached supersonic land vehicle speed is duobtful.
> > I saw it and heard it and some or all of the vehicle had supersonic
> > flow over it because there was indeed a boom. It was loud enough and
> > strong enough for me to have little doubt that the vehicle was above
> > Mach 1. My husband, who is Dryden's Chief Scientist, was right there,
> > too, and he says the same thing.
> Let's go back to the REASON behind the claim. The timing was done
> with a radar. This is the same radar used to verify the FIA records
> that the Blackbird holds for speed over a closed course. In other
> words, data exists from a calibrated instrument that shows the
> Budweiser rocket car did, indeed, exceed the speed of sound.
To be precise, an FPS-16 radar (although I don't remember if it was
ours or AFFTC's) tracking a radar beacon. This stuff is beyond
calibrated, being more like the standard. It's more like the platinum
bar that's the prime standard for the meter (well, before all the
hoo-ha about fractions of wavelengths that aren't real, tangible
metrics), from which all other instruments for determining length are
derived. Every calibrated instrument has a pedigree showing how its
calibration descends from the official standard. The number of
generations from the standard, as well as the associated variance, are
specified. The EDW radar system is used to calibrate all other
measurement systems (pacer aircraft, closed-course, the calibration of
air data systems, etc). Even the laser tracking systems were checked
against the radar.
For such an experiment, all instrumentation would be recalibrated,
too. Probably both before and after the record-setting run, just to
be sure that nothing drifted away from accuracy.
Additionally, the ground speed was measured with an array of
calibrated portable radar "guns" and the surface winds, etc, were
measured using calibrated meteorological instrumentation.
It's not like the Bud team went out and dashed across the lakebed
measuring the elapsed time with the lap timer function on an $3.99
digital watch. Rather, they were supported by what is universally
regarded as the best flight-test instrumentation system available
(other systems are as good, of course, but none are better).
Consider that the FAA, JAA, CAA, and other regulatory bodies accept
the data from this system without question, if you're wondering
whether I'm just supporting the local team, and manufacturers
determine the various takeoff and landing speeds, such as that speed
at which a takeoff can safely be refused, using this data. Every time
you fly in a Boeing or Douglas airliner, your life depends, in part,
on the accuracy of the EDW instrumentation.
Mary Shafer NASA Dryden Flight Research Center, Edwards, CA
SR-71 Flying Qualities Lead Engineer Of course I don't speak for NASA
firstname.lastname@example.org DoD #362 KotFR
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