Shuttle Questions Q & A (Part 4)

[elmarko]

hooooves - 30/11/2007  3:58 AM

Viewing/Listening HELP please!  I'm traveling down for my second launch this upcoming week and would love to listen live to the countdown as I view.  Using scanner or radio does anyone know if there is a non-delayed broadcast?  Last launch (116) would have been have been much more enjoyable if i weren't listening to a 10sec delay.  MUCH THANKS!

Scanner eh? Maybe try some of the NASA UHF/VHF frequencies. A lot of the radio traffic is digital now, but there are still some analogue frequencies in use.

[Zpoxy]

Jim - 28/11/2007  10:17 AM

Susan27 - 28/11/2007  10:15 AM

to the startracker: where is it at the pic above? Is it the small circle left of window 8?

in front of 3

There are two star trackers. The second one looks to the left of the orbiter (-Y). In the picture it is the dark spot below the letter "S" in "Startracker". Hope that helps.

[Susan27]

Hi,

I am interested in the different instrument-panels and their installed instruments on the shuttle`s flightdeck.

Do you therefor know if there are graphics, drawings of the instrument-panels available (online) combined with an explanation which instrument is situated where?

Thanks so much!

Kind regards

Susan

[Jim]

There is the SCOM on L2

[mkirk]

Susan27 - 30/11/2007  8:59 AM

Hi,

I am interested in the different instrument-panels and their installed instruments on the shuttle`s flightdeck.

Do you therefor know if there are graphics, drawings of the instrument-panels available (online) combined with an explanation which instrument is situated where?

Thanks so much!

Kind regards

Susan

There are several, the first one that comes to my mind is an older copy of part of (section 2) the SCOM (shuttle crew operations manual) which is available at this link:

http://www.shuttlepresskit.com/STS-105/scom.htm

This site is broken down by subsystem, at the back of each chapter are the CRT and Panel displays that are relevant to that particular system.  This will not only show you what the displays look like but give you a little info on how they work.

Although this version is a few years old it is acurate for the most part.  Chris has more recent Documentation in his L2 section.

Mark Kirkman

[Lee Jay]

I've wondered about this for a while, but the 122 thread is kicking me to ask.

If the Shuttle were to have to land at one of the emergency end of mission landing sites, how would the approach (including the HAC) and landing be guided?  They have a seemingly endless series of guidance systems and methods for KSC and Edwards (inertial, GPS, microwave, ground radar, visual, optical...it seems to go on and on), but I'm guessing many of the normal systems aren't available at all the various sites around the world, so what would be used in both day and night conditions?

[Susan27]

Hi,

I have a question concerning the SSME O2 purge (the "steam" coming out) prior launch at LC39A:

Do you know until what time in countdown-sequence (T minus...?) this purge is performed?

Many thanks!

[Jim]

Lee Jay - 30/11/2007  9:57 PM

I've wondered about this for a while, but the 122 thread is kicking me to ask.

If the Shuttle were to have to land at one of the emergency end of mission landing sites, how would the approach (including the HAC) and landing be guided?  They have a seemingly endless series of guidance systems and methods for KSC and Edwards (inertial, GPS, microwave, ground radar, visual, optical...it seems to go on and on), but I'm guessing many of the normal systems aren't available at all the various sites around the world, so what would be used in both day and night conditions?

The landing would be guided the same way.

Inertial guidance, GPS and air data are onboard the shuttle.

JSC makes the calls based of the telemetry from those systems

TACAN is at most ELS sites but GPS has taken over

MSBLS are at the TAL and EOM sites but that is for final approach

ground radar, visual, optical aren't used to guide the orbiter.


Mark Kirkman will correct me if I have made an error

[Jim]

Susan27 - 1/12/2007  6:46 AM

Hi,

I have a question concerning the SSME O2 purge (the "steam" coming out) prior launch at LC39A:

Do you know until what time in countdown-sequence (T minus...?) this purge is performed?

Many thanks!

Didn't get the right answers here?

http://orbit.m6.net/Forum/default.aspx?g=posts&m=172716

[mkirk]

Susan27 - 1/12/2007  5:46 AM

Hi,

I have a question concerning the SSME O2 purge (the "steam" coming out) prior launch at LC39A:

Do you know until what time in countdown-sequence (T minus...?) this purge is performed?

Many thanks!

I think you are referring to the oxygen coming out of the bottom of the main engine nozzles; this is oxygen that is draining from the turbopumps and is exiting via the drain lines.  This O2 is not to be confused with the nitrogen purge sequences that you here about.  The O2 is flowing through parts of the engines to help thermally condition them for the start sequence.  Hydrogen is also flowing through other parts of the engine for the same purpose.
The O2 will continue to vent out of the line drains from tanking until SSME start.

Mark Kirkman

[Jim]

mkirk - 1/12/2007  10:25 AM

Susan27 - 1/12/2007  5:46 AM

Hi,

I have a question concerning the SSME O2 purge (the "steam" coming out) prior launch at LC39A:

Do you know until what time in countdown-sequence (T minus...?) this purge is performed?

Many thanks!

I think you are referring to the oxygen coming out of the bottom of the main engine nozzles; this is oxygen that is draining from the turbopumps and is exiting via the drain lines.  This O2 is not to be confused with the nitrogen purge sequences that you here about.  The O2 is flowing through parts of the engines to help thermally condition them for the start sequence.  Hydrogen is also flowing through other parts of the engine for the same purpose.
The O2 will continue to vent out of the line drains from tanking until SSME start.

Mark Kirkman

And the O2 venting starts sometime during or right after tanking, I believe

[Lee Jay]

Jim - 1/12/2007  7:57 AM
MSBLS are at the TAL and EOM sites but that is for final approach

Really?  There was a huge list of sites in the other thread.  They're all equipped?  Is MSBLS the same as a normal runway localizer?

[Jim]

Lee Jay - 1/12/2007  11:14 AM

Jim - 1/12/2007  7:57 AM
MSBLS are at the TAL and EOM sites but that is for final approach

Really?  There was a huge list of sites in the other thread.  They're all equipped?  Is MSBLS the same as a normal runway localizer?

EOM is end of mission
ELS is emergency landing site.  I didn't say the ELS sites have MSBLS

[mkirk]

Lee Jay - 1/12/2007  10:14 AM

Jim - 1/12/2007  7:57 AM
MSBLS are at the TAL and EOM sites but that is for final approach

Really?  There was a huge list of sites in the other thread.  They're all equipped?  Is MSBLS the same as a normal runway localizer?

Take a look at the landing site table on pages 7-8 to 7-10 of the Space Shuttle Ascent Checklist at this site or in L2:

http://www.nasa.gov/centers/johnson/news/flightdatafiles/index.html

These are the 45 sites nominally “onboard the orbiter” although all of the other sites listed in the thread you refer to can be loaded if necessary.  Picking space shuttle landing sites for a given emergency will always be a tradeoff in terms of capability and the selection of a given site will largely be determined by the nature of the emergency and systems status of the orbiter.

As you can see from the table the three primary CONUS sites (Kennedy, Edwards, and Northrup) as well as the three primary TAL sites (Zaragoza, Moron, and Istres) are fully capable in terms of MLS, TACAN, and Preferred Runway length.

Selecting any of the other sites would result in risk tradeoffs.  For instance if a site without MLS was chosen then per the Flight Rules you would require higher weather minimums (ceiling, visibility, etc).

The orbiter is capable of getting to any runway by use of various Navaids (such as IMUs,TACAN, except for Endeavour which had all of the TACAN receivers replaced by GPS, GPS, MLS, Air Data, Radar Altimeter, etc) which are all processed by onboard GPC NAV (general purpose computer, navigation).

Mark Kirkman

[Lee Jay]

Thanks guys, I'm starting to get it.

So simplifying (probably over-simplifying), nav to the HAC and around the HAC would be accomplished on-board by IMUs and GPS.  Final approach would use the MLS if it's available, otherwise the Commander or Pilot would fly the final approach visually, thus the need for a higher ceiling and better visibility.  Is that correct?

[mkirk]

Lee Jay - 1/12/2007  11:25 AM

Thanks guys, I'm starting to get it.

So simplifying (probably over-simplifying), nav to the HAC and around the HAC would be accomplished on-board by IMUs and GPS.  Final approach would use the MLS if it's available, otherwise the Commander or Pilot would fly the final approach visually, thus the need for a higher ceiling and better visibility.  Is that correct?

Well not quite, for example the IMUs are being processed by NAV continuosly.  Maybe this chart that I attached will help illustrate what is happening.  Just think of the GPS - which is not on this chart - as being fuctionally the same as the TACAN within the NAV scheme, although GPS has proven to be far more precise.  Also DRAG H (listed in the first column, is basically an atmospheric drag model).

For some additional reading I would recommend the SCOM link I posted earlier in this thread.  Here it is again:

http://www.shuttlepresskit.com/STS-105/scom.htm

Look at the back of the GNC chapter under the Operations Description for Entry.


Mark Kirkman

[elmarko]

That's cool, Mark. What's the "Mach Jump" referring to?

[mkirk]

elmarko - 1/12/2007  12:03 PM

That's cool, Mark. What's the "Mach Jump" referring to?

This is the region of flight (Mach 1.6 to 1.1) where transients in the air data (sensed by probes that are deployed on the left and right of the orbiter's nose) can occur as aerodynamic shock waves pass over the probes.

Mark Kirkman

[Lee Jay]

Okay, thanks for the chart.  I think one of my misunderstandings was that I thought the HAC was formulated from ground sources, not from the on-board NAV.  I got this apparently-erroneous idea from the ground calls that they are on at the 180 etc.  It seems that if the crew has the same info as the ground that these calls wouldn't be necessary.  Thanks for clearing that up.

On final approach the HUD shows glide slope target and when to flare and so on.  I thought that stuff came from the microwave landing system like a normal airport localizer.  If MLS isn't there, this chart shows it would be replaced by TACAN or, now, GPS.  Would the HUD be driven the same way by these systems during final approach, or would that last 5000 feet be flown visually without benefit of the HUD glide slope and flare information?

[MKremer]

Lee Jay - 1/12/2007  12:54 PM

Okay, thanks for the chart.  I think one of my misunderstandings was that I thought the HAC was formulated from ground sources, not from the on-board NAV.  I got this apparently-erroneous idea from the ground calls that they are on at the 180 etc.  It seems that if the crew has the same info as the ground that these calls wouldn't be necessary.  Thanks for clearing that up.

It's like the "go at throttle up" call during ascent - done after the actual occurance, but just to let the crew know all the orbiter data the ground is monitoring was still looking good at that point.