Speed of Saturn V at first staging?

What was the speed of the Saturn V at the first staging? Wikipedia
says 9920 km/hr (2756 m/sec). "How Apollo Flew to the Moon" says
about 8500 km/hr (2361 m/s). This video
http://www.youtube.com/watch?v=F0Yd-GxJ_QM
shows 2770 m/sec.

The ratio of these two figures is very close to the ratio of a
nautical mile to a statute mile (1.15). Could the difference be
because of assuming the wrong kind of mile in a conversion?

I also thought about the velocity relative to space and relative to
the Earth, but the video must be relative to the Cape.
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On Mon, 03 Aug 2009 17:39:46 -0400, Jud McCranie
wrote:

What was the speed of the Saturn V at the first staging? Wikipedia
says 9920 km/hr (2756 m/sec). "How Apollo Flew to the Moon" says
about 8500 km/hr (2361 m/s). This video
http://www.youtube.com/watch?v=F0Yd-GxJ_QM
shows 2770 m/sec.


The Apollo 11 Press Kit says 9,064.5 ft/sec.

Brian

On Mon, 03 Aug 2009 18:20:49 -0500, Brian Thorn
wrote:

The Apollo 11 Press Kit says 9,064.5 ft/sec.

OK, that shouldn't suffer from confusion over the two types of mile.
That is 2763 m/s.
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Jud McCranie wrote:
On Mon, 03 Aug 2009 18:20:49 -0500, Brian Thorn
wrote:

The Apollo 11 Press Kit says 9,064.5 ft/sec.

OK, that shouldn't suffer from confusion over the two types of mile.

One would think, but then we don't know what the press office was fed
and what the original units were do we? I'm thinking Mars Climate
Orbiter may not have been the first unit confusion in NASA.

rick jones
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On Mon, 03 Aug 2009 18:20:49 -0500, Brian Thorn
wrote:

The Apollo 11 Press Kit says 9,064.5 ft/sec.

Is that relative to Earth or relative to space?
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On Tue, 04 Aug 2009 14:11:35 -0400, Jud McCranie
wrote:

Is that relative to Earth or relative to space?

Aparantly relative to space.
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Jud McCranie wrote:
On Tue, 04 Aug 2009 14:11:35 -0400, Jud McCranie
wrote:

Is that relative to Earth or relative to space?

Aparantly relative to space.

Prof. Newton gives you an A.
Prof. Einstein just gave you a D minus.

I'd say that was relative to the launch point, or Earth's surface
if you like.

Google is your friend:

Search inertial absolute reference frames

Or to save time:

http://en.wikipedia.org/wiki/Absolute_space

-and then-

http://en.wikipedia.org/wiki/Inertia...e_of_reference

(See Newton's inertial frame of reference, etc.)

Dave

On Tue, 04 Aug 2009 21:06:02 -0400, David Spain
wrote:

Aparantly relative to space.

Prof. Newton gives you an A.
Prof. Einstein just gave you a D minus.

I'd say that was relative to the launch point, or Earth's surface
if you like.

I found this PDF,
http://www.klabs.org/history/reports...1970023342.pdf
and the velocity in figure 1 starts off at about 405 m/s, which is the
speed of the rotational speed of the Earth at that latitude. So it is
relative to space, not to the Cape.
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Jud McCranie wrote:
On Tue, 04 Aug 2009 21:06:02 -0400, David Spain
wrote:

Aparantly relative to space.
Prof. Newton gives you an A.
Prof. Einstein just gave you a D minus.

I'd say that was relative to the launch point, or Earth's surface
if you like.

I found this PDF,
http://www.klabs.org/history/reports...1970023342.pdf
and the velocity in figure 1 starts off at about 405 m/s, which is the
speed of the rotational speed of the Earth at that latitude. So it is
relative to space, not to the Cape.

Aha, sorry, I was confused by the terminology in use.

Quoting from the referenced paper page 3 paragraph 3:
/quote
A guidance coordinate system (Xv, Yv, Zv)(Figs. 3 and 4) is
established with the origin at the center of the earth and with the Xv
axis lying along the vertical which intersects the calculated cutoff position
of the vehicle. Simplified equations of motion are derived to approximate
the motion over an oblate earth with a realistic gravitational field.
/endquote

In Figures 3 and 4 it says 'space-fixed' coordinate system with it's
origin at the earth's center. So this paper *is* describing it motion relative
to the earth's center, not the launch point. I was confused by the use of
the term 'relative to space', which really meant relative to the space-fixed
co-ordinate system that is relative to the Earth's center.

Assuming you are getting your velocity numbers from this same source or
at least cross-checking them with this source?

Dave

On Tue, 04 Aug 2009 22:35:35 -0400, David Spain
wrote:

to the earth's center, not the launch point. I was confused by the use of
the term 'relative to space', which really meant relative to the space-fixed
co-ordinate system that is relative to the Earth's center.

That is really what I meant but I didn't use the right terms.

Assuming you are getting your velocity numbers from this same source or
at least cross-checking them with this source?

I got the other figures I mentioned from other sources before I found
this. The others just gave the speed at staging, and I couldn't tell
whether it was relative to the Cape or not. The figures vary a
little, different flights, etc. But the data in Figure 1 is consist
ant with some of the others (but not all, e.g. "How Apollo Flew to the
Moon") and is clearly not relative to the Cape.
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