space ship one makes the target

"Paul Sengupta" wrote in message
...
"Tony Cox" wrote in message
ink.net...
Assuming the mode C is properly calibrated, that is.

How do you measure altitude at 328k feet? Surely a standard
barometric device isn't going to work?

Paul



Ground based radar? Inertial telemetry? GPS?

Good question...

Jay B in AZ

"Tony Cox" wrote in message
ink.net...
"Paul Sengupta" wrote in message
How do you measure altitude at 328k feet? Surely a standard
barometric device isn't going to work?

Paul

Below about 50 milliBar, people use a Pirani Gauge, which is
essentially a broken light bulb -- the wire gets hotter &
changes electrical resistance as there is less air to cool the
wire. 50mBar is around 75K ft.

Lower than about 10-2 milliBar, Ion gauges are the way to
go. They are like broken vacuum tubes.

Ah, thanks!

Paul

"Paul Sengupta"
wrote:

How do you measure altitude at 328k feet? Surely a standard
barometric device isn't going to work?

I set my Tivo to record the CNN coverage and Dick Rutan
mentioned that there were two tracking stations monitoring
the flight that could verify altitude to about "this far"
and he held his hands about 2 feet apart. I "think" he said
they were optical tracking stations. I presume there's
another form of on-board altimeter for measuring low
pressure or perhaps a radar altimeter.
Todd Pattist
(Remove DONTSPAMME from address to email reply.)
___
Make a commitment to learn something from every flight.
Share what you learn.

As I recall, Dick said something about Edwards and China Lake both tracking it
on radar. At best, that might give you a hundred meter accuracy.

A radar altimeter at 63 miles is a hell of a feat AND subject to severe angle
errors. I'd probably rely on GPS. As Dick indicated, two feet is about the
resolution you can get with a regular old GPS (unenhanced). That is my bet.

Jim


Todd Pattist
shared these priceless pearls of wisdom:

-I set my Tivo to record the CNN coverage and Dick Rutan
-mentioned that there were two tracking stations monitoring
-the flight that could verify altitude to about "this far"
-and he held his hands about 2 feet apart. I "think" he said
-they were optical tracking stations. I presume there's
-another form of on-board altimeter for measuring low
-pressure or perhaps a radar altimeter.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

"Jay Beckman" writes:

How do you measure altitude at 328k feet? Surely a standard
barometric device isn't going to work?

Ground based radar? Inertial telemetry? GPS?

Regardless, they'd better make damn sure that they get it right
otherwise someone is likely to run around telling the crowd how
long "to impact"...
http://www.avweb.com/newswire/10_24b.../187440-1.html

(Also...how does "inertial telemetery" determine altitude?!)

--kyler

Jim Weir wrote:

As I recall, Dick said something about Edwards and China Lake both tracking it
on radar. At best, that might give you a hundred meter accuracy.

Do you recall him holding his hands apart? I have to admit,
my attention was distracted right about then, so I can't
recall exactly what he said.

A radar altimeter at 63 miles is a hell of a feat AND subject to severe angle
errors.

I took a class in the early '70's on radar mapping of Venus
and the moon from ground based radar dishes. The basic
technique says you send out a spherical wave, and the
leading edge of your return wave is the closest point to
you. I don't have any info on radar altimeters, but
shouldn't they be reasonably self aligning if you get the
point below into your beam? I recognize that might be hard
for a craft in free-fall, but if it's not tumbling and the
beam width isn't too narrow ... of course, now you've got
power and detection problems at wide beam and 63 miles. :-)

I'd probably rely on GPS. As Dick indicated, two feet is about the
resolution you can get with a regular old GPS (unenhanced). That is my bet.

Makes sense. Cheaper too.

Todd Pattist
(Remove DONTSPAMME from address to email reply.)
___
Make a commitment to learn something from every flight.
Share what you learn.

I'm sure if they were smart enough to figure out how to get up there,
they were also smart enough to figure out how far up they got.

"Jay Beckman" wrote in message
news:_tZBc.7933$5t2.5921@fed1read01...
"Paul Sengupta" wrote in message
...
"Tony Cox" wrote in message
ink.net...
Assuming the mode C is properly calibrated, that is.

How do you measure altitude at 328k feet? Surely a standard
barometric device isn't going to work?

Paul



Ground based radar? Inertial telemetry? GPS?

Good question...

Jay B in AZ

Rutan answered it with "...these data come from the inertial nav
system."

"Dave Stadt" wrote in message news:SlKBc.745

We have the first astronaut of a civilian funded spacecraft.

I do believe civilians have funded every penny of the US space program.

Hey, kids, do you know how to spell PEDANTIC? I knewityoucould.


-c

"Dave Stadt" wrote in message news:PCVBc.149

I do believe that is wrong. Military personnel pay federal taxes, so
not every penny came from civilians.

And military pay comes from??????

Trolls.

I'm tired of my tax money going to FAA services going to trolls instead of
humans, so could you kindly not fly?

-c