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Author
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Topic: Saturn V roll maneuver
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paul.i.w
Member Posts: 65
From: UK
Registered: Feb 2006
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posted 02-25-2009 08:19 AM
   
Can someone tell me why the Saturn V performed a roll manoeuvre shortly after lift off? I can see why the yaw manoeuvre, to clear the tower, and the pitch to obtain the correct azimuth. But why the roll?I am sure the answer will be obvious once someone explains it to me patiently! Paul
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jasonelam
Member Posts: 691
From: Monticello, KY USA
Registered: Mar 2007
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posted 02-25-2009 08:25 AM
From the information that I have found, the roll program was designed to help roll the vehicle from a lanuch pad azimuth of 90 degrees to the orbital azimuth of 72 degrees. After the roll program was completed the spacecraft then pitched to arc out along the ground path. The shuttle does the same thing in order to roll from the azimuth of the launch pad to the azimuth of its target orbit. |
Spacepsycho
Member Posts: 819
From: Huntington Beach, Calif.
Registered: Aug 2004
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posted 02-25-2009 09:49 AM
I remember reading something from one of the astronauts who said the roll program was such a large movement, that he thought the spacecraft was tipping over. |
LCDR Scott Schneeweis
New Member Posts:
From:
Registered:
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posted 02-25-2009 09:55 AM
quote:
Originally posted by paul.i.w:
But why the roll?
Keep in mind the correct geometry was required to align the launch vehicle directional (line of sight) telemetry and communications antenna's with the ground...------------------
Scott Schneeweis
http://www.SPACEAHOLIC.com/ |
paul.i.w
Member Posts: 65
From: UK
Registered: Feb 2006
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posted 02-25-2009 10:08 AM
Is there a diagram anywhere describing the 3 axes of the Saturn V (ie a cylinder)? Was there a fixed orientation that the pitch and yaw were relative to?And surely it was the pitch manouevre that changed the azimuth? And I can see how it might be that the roll kept the communications aligned - was that the main reason for the roll? Paul |
art540
Member Posts: 432
From: Orange, California USA
Registered: Sep 2006
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posted 02-25-2009 10:23 AM
Lunar missions require roll to adapt to changing azimuth simply because the moon is a moving body in distance, speed and inclination. In a launch window the azimuth changes and updating is needed if the T-0 is missed. Pitch is the angle to the horizon while roll aligns the pitch axis to the azimuth prior to the pitchover. Sorta like turning your car wheels to the direction you wish to go. |
Proponent
Member Posts: 59
From: London
Registered: Oct 2008
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posted 02-25-2009 11:48 AM
Would abort modes be a factor in determining the appropriate roll angle too? That is, would the direction in which the LES or, at higher altitudes, the SPS, yanks the CM need to be considered? |
paul.i.w
Member Posts: 65
From: UK
Registered: Feb 2006
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posted 02-25-2009 12:42 PM
Thanks for the replies. I think I misunderstood what a roll is in a spacecraft. It is not just the rocket rotating about a fixed longitudinal axis but it is also changing direction – banking to the left or right I suppose? |
LCDR Scott Schneeweis
New Member Posts:
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posted 02-25-2009 12:46 PM
The Astrionics Systems Handbook provides the reference points/axis orientation with respect to Roll/Pitch/Yaw for each stage. If you cant find on line will email a copy. |
paul.i.w
Member Posts: 65
From: UK
Registered: Feb 2006
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posted 02-25-2009 05:15 PM
Thanks for the pointer, Scott, I have managed to locate a copy.Paul |
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