*OH-TEE* Space Shuttle 'S-Turs' *OH-TEE*

[PRB]

Ok, who knows the answer to this?
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
While watching the NASA TV coverage of the Space Shuttle’s landing at Edwards AFB, I noticed they don’t call those energy-dissipating maneuvers “s-turns” anymore, but “roll and roll reversals.” This is interesting and seems to makes sense…
<o></o>
If you were to draw a line on a map tracing the course of the ship during these “s-turns”, would the line describe an “S”, or would it be straight? Meaning, is the ship really doing s-turns, in the manner that P-51Ds did to stay with the B-17s over Europe? I’m thinking now that what’s really happening is that the ship, zorching into the thin air at 300,000 feet and 15,000 knots, is absolutely incapable of making “A”, “B”, or “C” turns, to say nothing of “S” turns! I’m guessing that what’s really happening is that the ship alternately presents a left wing down, then a right wing down, VERY high AOA profile to the airflow during this period of entry. In other words, the ship is “flying” belly first into the “wind”, first with the left wing down, then the right, the switching from left to right being accomplished by “reversing the roll” at various times. And during this whole time, the ships velocity vector is, more or less, a straight line.
<o></o>
But that’s just a guess, more or less.
<o></o>
And how many of these “roll reversals” is actually done during the entry? From watching today, it seemed like just two, one to the left, and one to the right. By the time they were done with the second one they were over Edwards. Of course I’m relying of that NASA TV commentator dude for most of this…

 

[BananaBob]

I watched it too, always try to watch them, people take them for granted until a crash and then they forget about them again. It's cool that they traveled over 5 million miles with all the orbits and the mere fact that there are projectiles up there traveling much faster than bullets scattered everywhere, man they are heroes and there are untold benefits to be gained by their research. :ernae:

 

[CodyValkyrie]

I couldn't tell you the actual flight path, but these roll reversals are made simply to slow the aircraft down and are completely automated based on mission data entered into the aircraft and by ground control, all depending on the location of entry, etc. The pilots usually are incapable of flying them manually, however should a major system failure occur, they DO have the ability to make manual inputs.

I'm willing to bet if you asked the guys over at Space Shuttle Simulator 2007 forums, they could answer you better. My experience with the Space Shuttle comes from my work over there, so nothing concrete.

 

[Cazzie]

Wouldn't miss a shuttle launch or landing if I could help it.

Heck, I get excited watching GA take-off and land.

Caz

 

[Lateral-G]

They are 'esses' but probably wouldn't be noticed to much on a ground track plot unless you had a real tight zoom on it. I don't think the cross track range is a lot. Basically, as you know, making a turn causes you to lose speed/energy and since it takes so many miles to get your speed down when gliding and the shuttle has limited miles to travel from entry to touchdown the only way to increase this needed distance is to make those 'S' turns. You're trading the longitudinal distance for lateral (or cross track) distance.

You might ask why not just de-orbit further out? You could but then you'd spend more time in heat generating re-entry. They want to get through re-entry as quick as possible and into the atmosphere. You have a higher energy rate, true, but you can bleed that off with aerodynamic manuevering.

-G-