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How long does it take to the space shuttle to change its orientation while operating out of the Earth's atmosphere, either by turning or rolling? I.e. what is the average/maximum rotation speed? What is its maximum acceleration while performing these maneuvers?

What is the technical limit given by mass and thrusters' power? What about limits dictated by crew safety or other similar concerns?

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  • $\begingroup$ in atmosphere (alierons, rudder) or in space (RCS)? With the tank and SRBs still attached, or orbiter alone? $\endgroup$ – SF. Mar 24 '16 at 13:20
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    $\begingroup$ In addition to @SF. 's question. are you asking about the max possible rate, the max rate that was actually used, the rates that were normally used, or what. The digital autopilot was highly configurable. $\endgroup$ – Organic Marble Mar 24 '16 at 15:22
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    $\begingroup$ Nobody wants to, but it did happen news.google.com/… $\endgroup$ – Organic Marble Mar 24 '16 at 16:39
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    $\begingroup$ One basic thing to remember is that if high angular rates are achieved during attitude changing maneuvers, it comes at the cost of propellant consumption. In general, the slower the angular rate used, the less propellant consumption - the limiting case being a minimum duration vernier jet impulse to get moving, then one to arrest said motion as the desired attitude is achieved. Relatively rapid angular rates were used right after external tank separation. $\endgroup$ – Digger Mar 25 '16 at 15:52
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    $\begingroup$ @OrganicMarble Yes, alarmingly high rotational rates were seen on at least one other mission. On STS-87, an attempt to grapple the free-flying SPARTAN payload failed. While the crew was attempting to get Columbia into position to attempt another grapple, rotational rates reached a high enough level such that Mission Control had to call them off the attempt. Source? Bar talk. $\endgroup$ – Digger Mar 25 '16 at 16:03
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I can answer the "average" part. Here's a table from my usual go-to source for openly available Shuttle details, the Shuttle Crew Operations Manual, page 1009.

enter image description here

In this table, "PRCS" refers to the large Primary Reaction System jets, and "YRCS" is a typo for the smaller Vernier Reaction System jets. "NORM" and "LOW" are different settings on the Digital Autopilot. "FWD" and "AFT" refer to the different RCS pods in the Orbiter.

(The RCS system was divided up in two ways - a forward pod in the nose in front of the crew cabin, and aft pods located to the left and right of the vertical tail. Within each system, there were Primary thrusters (~900 lbs thrust) and Vernier thrusters (~25 lbs thrust). Each pod had an independent propellant system. The two aft pods could be interconnected, or cross-fed to the Orbital Manuevering System engines. There was no interconnect to the forward pod.)

So much for accelerations. For rates, everything depended on the Digital Autopilot settings, which were extremely flexible and reconfigurable, and therefore highly complex. The settings could be pre-loaded or changed by the crew in flight. Rotation rates and deadbands varied widely depending on mission phase, payload operations etc. Here are a few examples from the same source:

A7/VERN – Used for attitude hold (1 deg attitude deadband, 0.016 deg/sec rotation rate)

B7/PRI – Used for maneuvers (2 deg attitude deadband, 0.5 deg/sec rotation rate)

(page 1144)

Re: the A7 and B7 nomenclature:

Each planned DAP configuration is given a reference number. In general, the A configurations have larger deadbands and slower maneuvering rates than the B configurations. The wider deadbands of the A configurations are used to minimize fuel usage, while the tighter deadbands of the B configurations allow greater precision in executing maneuvers or holding attitude.

(page 520)

For some more detailed DAP settings, here are the tables for the last Shuttle mission, from the STS-135 Orbit Ops Flight Supplement. (starts on page 34)

enter image description here enter image description here enter image description here enter image description here

Here's a brief writeup on the Orbital DAP. There's much more at the source.

The rotation rates and dead bands, translation rate and certain other DAP options can be changed by the flight crew during the orbit phase using the DAP CRT display. The flight crew can load the DAP with these options in two ways: one option set may be accessed by depressing the DAP A push button on the orbital DAP panel, the other by depressing the DAP B push button. For convenience, each planned DAP configuration is given a number and is referred to by that number and the DAP used to access it. Typically, the DAP A configurations will have larger dead bands and higher rates than the DAP B configurations. The wide dead bands are used to minimize fuel usage, while the tight dead bands allow greater precision in executing maneuvers or in holding attitude.

The RCS DAP can operate in both an automatic and a manual rotation mode, depending on whether the flight crew selects the auto or man push button light indicators on the orbital DAP panel. The manual mode is also accessed when the RHC is moved out of its detent (neutral) position. In both the automatic and manual modes, the rotation rate is controlled by the selection of DAP A or B and the information loaded in the DAP config display. In addition, in automatic, the DAP determines the required attitude to be achieved from universal pointing and then computes the RCS jet fire commands necessary to achieve these requirements within the current set of dead bands. In the manual rotation mode, the RCS DAP converts flight crew inputs with any of the three RHCs to RCS jet fire commands, depending on whether pulse, disc rate or accel is selected on the orbital DAP panel. Simply, when pulse is selected, a single burst of jet fire is produced with each RHC deflection. The resultant rotational rate is specified on the DAP config display. When disc rate is selected, jet firings continue to be made as long as the RHC is out of detent in order to maintain the rotational rate specified on the DAP config display. When accel is selected, continuous jet firings are made as long as the RHC is out of detent.

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    $\begingroup$ "Page 1009"? Now that is a thorough search... Very good answer, let's see if others pop up before accepting it $\endgroup$ – Marco Bolis Mar 25 '16 at 6:23
  • $\begingroup$ Can you find anything on rates? $\endgroup$ – Russell Borogove Mar 25 '16 at 12:36
  • $\begingroup$ @RussellBorogove I added some rate info. That's where it really gets complex but I tried to explain most of the terminology. Let me know if it needs more. $\endgroup$ – Organic Marble Mar 25 '16 at 12:59
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The flight computers limited the rates in all directions allowed, however it was possible to disable those limits. This was automatically done for 2 and 3-engine out scenarios. I suspect the limits were set by K-Load pre-processing. There were not hard limits as numbers typed into the code.

The shuttle is a rate control system. Rates of roll, pitch and yaw are requested/introduced, unlike with other aircraft which use deflection-based controls. If you introduce a roll in 1 direction, to stop, you must introduce the exact same force in the opposite direction. The pilots learn to fly the shuttle with this in mind. Even in atmosphere, it is still a rate-control system. They do not pull back on the stick for very long. They pulse the stick to introduce and counteract those rate inputs.

Source: I wrote or reviewed the code that disabled the rate limits on 2/3-EO flight regimes.

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  • $\begingroup$ If there is enough time to do a certain roll, pitch or yaw maneuver in some minutes, doing it in some seconds only would be a waste of maneuver porpellants reserves. $\endgroup$ – Uwe Mar 6 '17 at 20:37

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