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bonzaman
4th Aug 2001, 10:56
I understand that every landing of the Space Shuttle is, in effect, a glide approach. I also believe that this power off phase starts from a very high altitude. How is the approach controlled, given variations in wind strenght and drift to ensure an arrival within the required margin?

captain
4th Aug 2001, 13:04
If I understand correctly the shuttle leaves orbit in a calculated window. Passed this window a full orbit has to be performed before a new entry can be made. The shuttle then enters the atmosphere at around Mach 25 over Washington state. During a continuous decellerating descent it becomes controllable with its flight controls at around Mach 7. It overflies the space shuttle landing facility at Kennedy space port at 30,000 ft and Mach 2. On downwind it becomes subsonic, hence the double sonic boom. It turn final at 10,000 ft, following a 'meat ball' type vasi, which is positioned at 1 NM final. Then it switches to a 3 degree glide angle to touch down at 200Kt. Mannually or automatically flown, using actual and predicted wind and temp. information.
SJ

[ 04 August 2001: Message edited by: Switch Jock ]

BEagle
4th Aug 2001, 15:00
After completion of the energy management manoeuvre, the final descent is realtively straightforward. If you ever get to the Johnson Sace Center in Houston, you can have a play on the touchdown simulators for free - use the command bars on the ADI rather than being tempted to 'go visual' early though!

tony draper
4th Aug 2001, 15:22
I recal a very good simulation prog of the Shuttle approach and landing, it was quite a while back and a dos prog, so probably unavailable now.

[ 04 August 2001: Message edited by: tony draper ]

ft
4th Aug 2001, 16:31
The shuttle simulator can be found on the net as downloadable abandonware so make a search if interested. Sorry, don't know where I saw it.

(Edit) You can see a bit more about the PC shuttle sim I was talking about here:
http://www.theunderdogs.org/game.php?name=Shuttle

Of course, don't download it without prior written permission from the copyright holder as abandonware is still a legal grey zone... ;)

For more interesting links,
http://www.hobbyspace.com/Simulators/index.html

seems to be a good place to go.

Cheers,
/ft

[ 04 August 2001: Message edited by: ft ]

RW-1
4th Aug 2001, 16:55
The shuttle flies a controlled energy management profile from deorbit to landing, my likely be the most reasearched vehicle in terms of flight dynamics as to energy/distance/atmospheric conditions.

The shuttle flies towards the selected HAC (Heading alignment cylender) for the runway selected, on the way in during hypersonic flight, launch energy must be dissipated, this is accomplished by a series of S-turns, usually two of them in sequenbce, with up to a 45 deg bank (if one doubts this, watch the MSC shuttle attitude monitors during the re entry sequence).

They have readouts as to the limits of range available, energy state, and the system also projects this information in vertical and horizontal formats, projecting the future position of the shuttle at 40, 40, and 60 seconds (horozontal flight situation disp).

A very highly orchestrated sequence, from de-orbit to landing.

The program in question is called Precision Approach. One can DL a demo here:
http://www.binarystarltd.com/pa_demo.htm

I have the full version on Disk, if there is interest, please email me and I can upload the contents to my website for DL.

As for the rest, geez mon, just paste a link:
http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts_mes.html#mes_deorbit

[ 04 August 2001: Message edited by: RW-1 ]

cudgy_funt
4th Aug 2001, 18:43
There was an article in PilotMagazine not so long ago, where one of the reporters (i forget his name) flew the proper Astronaut Training Sim. Apparantly, the Astronauts follow a HUD command which takes all variables (wind speed, altitude, speed, etc) and providing the PIC follows the command, a perfet landing is assured every time.

BigJETS
4th Aug 2001, 19:51
Interesting.
What exactly makes, or does not make an entry "window"??

411A
4th Aug 2001, 19:53
Surprised that no one mentioned one additional bit of hardware---DLC, yes the same as on the TriStar. :D

RW-1
4th Aug 2001, 22:45
The entry window is just the period of time while on orbit where the OMS burn will provide the proper deceleration to the shuttle's orbit so that the track/altitude will take the orbiter into the atmosphere (entry interface), and to the selected landing site.

BTW the double sonic boom is due too the fact that there are two shock waves on any supersonic traveling object, most know of the bow front, but you also have one from the rear, also trailing back, in the case of the Shuttle, it's speed over land is such that you can hear the two quite distinctly.

[ 04 August 2001: Message edited by: RW-1 ]

bonzaman
5th Aug 2001, 09:52
Thank you all for your replies, and the links. You have really opened up the subject for me.

Dave Incognito
5th Aug 2001, 12:36
Take a look at:
http://www.dfrc.nasa.gov/gallery/photo/index.html

Scroll down to STS - Space Shuttle section, and you will find a whole bunch of great mpegs that you can download. Some of the best ones show the shuttle being launched from the 747 transporter.

How's it Hanging
7th Aug 2001, 14:14
Stayed with a guy once who worked for IBM. Was their Nasa manager from the last Appollo missions through to the first 5 or 6 shuttle missions.
Had some good stuff in his house such as moon rock, shuttle tiles etc.
The pilots actually practise the approach in a specially modified G11, with shuttle instrumentation, HUD, etc on one side and conventional on the other. They go up to 45000' have a set configuration for the aircraft which follows the shuttle profile and fly the approaches.
He had been up a few times with the guys as during the early days they used to go up before the shuttle committed, and fly the proposed approach a few times to see if everything was working.
Also said on the computer side of things that they tried to tell Nasa that the onboard computers needed x amount of time to fire up and cross check and align each other before a launch. It was somethig like 45 minutes. Nasa decided that in their launch sequence they wanted the computers to start doing their stuff at 40 minutes. Thus the delays with some of the early launches because of computer problems. Actually nothing wrong with them, just not enough time. Needless to say the pre launch sequence was changed! :D

Kerosene Kraut
7th Aug 2001, 20:16
There is a very nice Shuttle-Simulator (not only!). Try www.x-plane.com (http://www.x-plane.com)

Multp
8th Aug 2001, 03:23
The T-38 Talon is also used to simulate the Shuttle Approach. Final approach is with gear down, full flap, airbrakes out and engines at idle, target IAS 240 knots, flare at 200ft. Did this once out at Edwards: mind blowing!