Author Topic: Shuttle Q&A Part 5  (Read 1542527 times)

Offline MCC Tech

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Re: Shuttle Q&A Part 5
« Reply #540 on: 09/03/2009 12:27 am »
Quote
Quote by elmarko: 
Actually, that's a request for L2, potentially. Is there any kind of documentation about the DVIS system? I'd be really interested, as someone who sometimes deals with audio routing and the like (we have radio studios at my university job).

DVIS is one of the systems I work on.   I'll see if I can find a keyset users manual tonight and get it scanned for L2.

Offline elmarko

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Re: Shuttle Q&A Part 5
« Reply #541 on: 09/03/2009 08:47 am »
You're wonderful, thank you so much!

Is there any kind of orientation training manual kind of thing for new users, or do they just get given the manual?

Offline Danny Dot

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Re: Shuttle Q&A Part 5
« Reply #542 on: 09/03/2009 11:14 pm »
I have quantified the effect of increased alpha on heating, but I think we should move the discussion and leave this thread for shorter Q&As.

http://forum.nasaspaceflight.com/index.php?topic=8080.msg471678#msg471678

Danny Deger
« Last Edit: 09/03/2009 11:55 pm by Danny Dot »
Danny Deger

Offline Jorge

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Re: Shuttle Q&A Part 5
« Reply #543 on: 09/04/2009 12:39 am »
You're wonderful, thank you so much!

Is there any kind of orientation training manual kind of thing for new users, or do they just get given the manual?

I don't recall even getting the manual. DVIS is one of those things you learn by having a senior sit next to you and show you how to use it. It has some fancy features but 90% of what a flight controller will ever use it for can be learned in ten minutes.
JRF

Offline Danny Dot

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Re: Shuttle Q&A Part 5
« Reply #544 on: 09/04/2009 03:16 am »
You're wonderful, thank you so much!

Is there any kind of orientation training manual kind of thing for new users, or do they just get given the manual?

I don't recall even getting the manual. DVIS is one of those things you learn by having a senior sit next to you and show you how to use it. It has some fancy features but 90% of what a flight controller will ever use it for can be learned in ten minutes.

I agree.  It is well designed and has an intuitive interface.  My dishwasher on the other hand....

Danny Deger
Danny Deger

Offline oxford750

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Re: Shuttle Q&A Part 5
« Reply #545 on: 09/05/2009 01:56 am »
It's really hard to visualise it.

I don't suppose anyone fancies a crack at drawing a diagram or something, because to me all I can think of is the orbiter banking past 90 degrees and then after 90 the white stuff is facing the ground...


It is actually very easy to visualize. Take a foam orbiter toy. Shove a stick into the belly at a 40 degree angle below the nose. That is the relative wind vector. It is also the X axis of the stability axis frame. That is the key. The bank is performed about stability axes, not body axes.

Now orient the toy so that you're looking down the stick at the belly. You're seeing the orbiter from the relative wind point of view. As long as the relative wind is aligned with the stick, the proper angle of attack (alpha) of 40 and sideslip angle (beta) of zero are maintained.

Now rotate the orbiter toy about the stick so that the belly is on top and the nose is pointed 40 degrees down. That's a prebank of 180. But the relative wind is still looking at the black belly, not the white tiles.

That's the key. When you perform a "roll" during entry you are rolling about the stability axes (the stick) and not the body axes (the nose). If you rolled 180 about the body axes you'd wind up with the top (white tiles) facing the wind. But a roll about stability axes always keeps the black side facing the wind.

Jorge, I have read this explaianation over and over and still can't picture it.  where can I find a drawing of this?

Even stick figures will help as I am not a member of L2.

Thanks
Oxford750

Offline oxford750

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Re: Shuttle Q&A Part 5
« Reply #546 on: 09/05/2009 02:19 am »
To whom it may concern:

How can the (small compared to ISS) shuttle, or even the russian segment, for that matter, boost the orbit of the ISS?  I mean don't you need MORE more thrusters spread out along the truss on both sides (like the shuttle) to boost the mass of ISS.

Thanks
Oxford750

Offline Jorge

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Re: Shuttle Q&A Part 5
« Reply #547 on: 09/05/2009 02:20 am »
It's really hard to visualise it.

I don't suppose anyone fancies a crack at drawing a diagram or something, because to me all I can think of is the orbiter banking past 90 degrees and then after 90 the white stuff is facing the ground...


It is actually very easy to visualize. Take a foam orbiter toy. Shove a stick into the belly at a 40 degree angle below the nose. That is the relative wind vector. It is also the X axis of the stability axis frame. That is the key. The bank is performed about stability axes, not body axes.

Now orient the toy so that you're looking down the stick at the belly. You're seeing the orbiter from the relative wind point of view. As long as the relative wind is aligned with the stick, the proper angle of attack (alpha) of 40 and sideslip angle (beta) of zero are maintained.

Now rotate the orbiter toy about the stick so that the belly is on top and the nose is pointed 40 degrees down. That's a prebank of 180. But the relative wind is still looking at the black belly, not the white tiles.

That's the key. When you perform a "roll" during entry you are rolling about the stability axes (the stick) and not the body axes (the nose). If you rolled 180 about the body axes you'd wind up with the top (white tiles) facing the wind. But a roll about stability axes always keeps the black side facing the wind.

Jorge, I have read this explaianation over and over and still can't picture it.  where can I find a drawing of this?

Even stick figures will help as I am not a member of L2.

Thanks
Oxford750

Here is a drawing from the Entry DAP Workbook.

JRF

Offline AlexInOklahoma

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Re: Shuttle Q&A Part 5
« Reply #548 on: 09/05/2009 02:26 am »
Ok - stick figures it is  :-)  And I am not positive that I got this right, but I will try.  In my pic, the upper Orbiter is with bottom towards ground and travelling to the 'left' of pic...arrow indicates direction of air/wind that Orbiter is 'seeing' upon its surfaces/wings. (angle0of-attack of wings is approximate but should give general idea)

Lower pic is after Orbiter 'rolls' 180 over onto its 'belly', so to speak.  However, notice how its the 'bottom' that is striking the 'wind'?  Yes, the top is facing downwards, but nothing else has changed for the most part, particularly the angle-of-attack of the wings -v- airflow.  Its a position kind of like when an airplane is about to touchdown on landing (if that helps?)...

I realize my terms are not standard, but trying to 'dumb it down' (no offense to anyone!).  Jorge's explanation got me FINALLY picturing all this in my head, and I am (used to be anyways) a licensed pilot, LOL!  Thanks, Jorge..seriously, it helped me more than you may realize!

Anyways, hope that helps, and I truly hope that I am showing things correctly...  not too shabby for a quick Paint sketch, 'eh?

Alex

Edit - Jorge beat me to the pic...and I like his pic much better  :-)
« Last Edit: 09/05/2009 02:28 am by AlexInOklahoma »

Offline Danny Dot

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Re: Shuttle Q&A Part 5
« Reply #549 on: 09/05/2009 03:23 am »
Ok - stick figures it is  :-)  And I am not positive that I got this right, but I will try.  In my pic, the upper Orbiter is with bottom towards ground and travelling to the 'left' of pic...arrow indicates direction of air/wind that Orbiter is 'seeing' upon its surfaces/wings. (angle0of-attack of wings is approximate but should give general idea)

Lower pic is after Orbiter 'rolls' 180 over onto its 'belly', so to speak.  However, notice how its the 'bottom' that is striking the 'wind'?  Yes, the top is facing downwards, but nothing else has changed for the most part, particularly the angle-of-attack of the wings -v- airflow.  Its a position kind of like when an airplane is about to touchdown on landing (if that helps?)...

I realize my terms are not standard, but trying to 'dumb it down' (no offense to anyone!).  Jorge's explanation got me FINALLY picturing all this in my head, and I am (used to be anyways) a licensed pilot, LOL!  Thanks, Jorge..seriously, it helped me more than you may realize!

Anyways, hope that helps, and I truly hope that I am showing things correctly...  not too shabby for a quick Paint sketch, 'eh?

Alex

Edit - Jorge beat me to the pic...and I like his pic much better  :-)

You got it perfectly -- including the terms. 

And I like your picture better  :)

On boosting station.  I don't know the details, but you can boost with a small single thruster through the center of gravity it you burn it a long time.

Danny Deger
« Last Edit: 09/05/2009 01:25 pm by Danny Dot »
Danny Deger

Offline MKremer

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Re: Shuttle Q&A Part 5
« Reply #550 on: 09/05/2009 04:10 am »
To whom it may concern:

How can the (small compared to ISS) shuttle, or even the russian segment, for that matter, boost the orbit of the ISS?  I mean don't you need MORE more thrusters spread out along the truss on both sides (like the shuttle) to boost the mass of ISS.

Thanks
Oxford750

It's not so much the quantity or size of the thrusters as much as where they're located and how much time is needed for the burn.

Note that either the Russian segment or Progress thrusters can used for reboosts (and usually are).


Offline oxford750

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Re: Shuttle Q&A Part 5
« Reply #551 on: 09/05/2009 05:56 am »
Ok - stick figures it is  :-)  And I am not positive that I got this right, but I will try.  In my pic, the upper Orbiter is with bottom towards ground and travelling to the 'left' of pic...arrow indicates direction of air/wind that Orbiter is 'seeing' upon its surfaces/wings. (angle0of-attack of wings is approximate but should give general idea)

Lower pic is after Orbiter 'rolls' 180 over onto its 'belly', so to speak.  However, notice how its the 'bottom' that is striking the 'wind'?  Yes, the top is facing downwards, but nothing else has changed for the most part, particularly the angle-of-attack of the wings -v- airflow.  Its a position kind of like when an airplane is about to touchdown on landing (if that helps?)...

I realize my terms are not standard, but trying to 'dumb it down' (no offense to anyone!).  Jorge's explanation got me FINALLY picturing all this in my head, and I am (used to be anyways) a licensed pilot, LOL!  Thanks, Jorge..seriously, it helped me more than you may realize!

Anyways, hope that helps, and I truly hope that I am showing things correctly...  not too shabby for a quick Paint sketch, 'eh?

Alex

Edit - Jorge beat me to the pic...and I like his pic much better  :-)

Wow I never knew that the shuttle did that to "bleed off speed" or do I have it wrong. After seeing that I realized that I DID have the "right" picture in my mind, I just needed a conformation.

Thanks AlexInOklahoma



















Offline Jorge

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Re: Shuttle Q&A Part 5
« Reply #552 on: 09/05/2009 06:05 am »
Ok - stick figures it is  :-)  And I am not positive that I got this right, but I will try.  In my pic, the upper Orbiter is with bottom towards ground and travelling to the 'left' of pic...arrow indicates direction of air/wind that Orbiter is 'seeing' upon its surfaces/wings. (angle0of-attack of wings is approximate but should give general idea)

Lower pic is after Orbiter 'rolls' 180 over onto its 'belly', so to speak.  However, notice how its the 'bottom' that is striking the 'wind'?  Yes, the top is facing downwards, but nothing else has changed for the most part, particularly the angle-of-attack of the wings -v- airflow.  Its a position kind of like when an airplane is about to touchdown on landing (if that helps?)...

I realize my terms are not standard, but trying to 'dumb it down' (no offense to anyone!).  Jorge's explanation got me FINALLY picturing all this in my head, and I am (used to be anyways) a licensed pilot, LOL!  Thanks, Jorge..seriously, it helped me more than you may realize!

Anyways, hope that helps, and I truly hope that I am showing things correctly...  not too shabby for a quick Paint sketch, 'eh?

Alex

Edit - Jorge beat me to the pic...and I like his pic much better  :-)

Wow I never knew that the shuttle did that to "bleed off speed" or do I have it wrong. After seeing that I realized that I DID have the "right" picture in my mind, I just needed a conformation.

Thanks AlexInOklahoma




















Well, more accurately the orbiter *could* do that if it needed to. To my knowledge, we've never done a prebank of 180. I kinda doubt it's ever gone past 90, actually.
JRF

Offline MKremer

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Re: Shuttle Q&A Part 5
« Reply #553 on: 09/05/2009 06:09 am »

Wow I never knew that the shuttle did that to "bleed off speed" or do I have it wrong. After seeing that I realized that I DID have the "right" picture in my mind, I just needed a conformation.

Thanks AlexInOklahoma

Speed is relative. What the whole reentry profile/trajectory is doing is managing/bleeding off energy all the way to the runway.

What made my lightbulb blink on years ago was changing my focus from just speed to energy - it lets you view the entire sequence from orbit to landing in a much more logical and understandable fashion - the safest way so large amount of orbital energy is dissipated during reentry.

 

Offline oxford750

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Re: Shuttle Q&A Part 5
« Reply #554 on: 09/05/2009 06:20 am »
To whom it may concern:

How can the (small compared to ISS) shuttle, or even the russian segment, for that matter, boost the orbit of the ISS?  I mean don't you need MORE more thrusters spread out along the truss on both sides (like the shuttle) to boost the mass of ISS.

Thanks
Oxford750

It's not so much the quantity or size of the thrusters as much as where they're located and how much time is needed for the burn.

Note that either the Russian segment or Progress thrusters can used for reboosts (and usually are).



Thanks for that answer however the other problem I am having is with the center of gravity. I mean is the shuttle "not" on the "wrong" side of the stations center of gravity as opposed to Directly beneth it, (ie the thusters at the nose and the tail of the shuttle are an equall distance from the "middle" of the payload bay) therefore imparting the station to "roll" and or "yaw" and the same thing with the russain segment ?


Hope I made sense.
Thanks
Oxford750

Offline hop

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Re: Shuttle Q&A Part 5
« Reply #555 on: 09/05/2009 06:56 am »
Thanks for that answer however the other problem I am having is with the center of gravity. I mean is the shuttle "not" on the "wrong" side of the stations center of gravity as opposed to Directly beneth it, (ie the thusters at the nose and the tail of the shuttle are an equall distance from the "middle" of the payload bay) therefore imparting the station to "roll" and or "yaw" and the same thing with the russain segment ?
This probably belongs in ISS Q&A, but anyway... the thrust doesn't have to be exactly through the center of the stacks CG. You can counter the torques with other thrusters, it just burns some additional propellant.

Thrust a long the long axis of the station (i.e. a Progress or ATV docked on the end of Zvezda firing rearward facing engines) is pretty close to the CG, and AFAIK this is the preferred configuration to do reboosts.
« Last Edit: 09/05/2009 06:56 am by hop »

Offline MKremer

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Re: Shuttle Q&A Part 5
« Reply #556 on: 09/05/2009 08:26 am »
This probably belongs in ISS Q&A, but anyway... the thrust doesn't have to be exactly through the center of the stacks CG. You can counter the torques with other thrusters, it just burns some additional propellant.

Thrust a long the long axis of the station (i.e. a Progress or ATV docked on the end of Zvezda firing rearward facing engines) is pretty close to the CG, and AFAIK this is the preferred configuration to do reboosts.

Is it not true that the stack can be re-oriented via CMGs so that the thrust is pretty close to the total CG (or is that what you're saying, with other thrusters or CMGs making up the difference to keep the stack steady)?

Offline Danny Dot

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Re: Shuttle Q&A Part 5
« Reply #557 on: 09/05/2009 01:28 pm »
snip

Well, more accurately the orbiter *could* do that if it needed to. To my knowledge, we've never done a prebank of 180. I kinda doubt it's ever gone past 90, actually.

Correct.  So far it has always entered wings level, but quickly goes to almost 90 to keep from skipping back up into the vacuum of space.

I am proposing it start coming in at 90 in the first place -- 90 degrees prebank.

Danny Deger
Danny Deger

Offline Antares

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Re: Shuttle Q&A Part 5
« Reply #558 on: 09/05/2009 03:57 pm »
where can I find a drawing of this?

Here's a good wiki article, with words describing the axes (no pictures).  There are 3 books listed in the references.  I've seen Roskam's on many, many shelves.
http://en.wikipedia.org/wiki/Stability_derivatives
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline oxford750

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Re: Shuttle Q&A Part 5
« Reply #559 on: 09/05/2009 04:59 pm »
Thanks for that answer however the other problem I am having is with the center of gravity. I mean is the shuttle "not" on the "wrong" side of the stations center of gravity as opposed to Directly beneth it, (ie the thusters at the nose and the tail of the shuttle are an equall distance from the "middle" of the payload bay) therefore imparting the station to "roll" and or "yaw" and the same thing with the russain segment ?
This probably belongs in ISS Q&A, but anyway... the thrust doesn't have to be exactly through the center of the stacks CG. You can counter the torques with other thrusters, it just burns some additional propellant.

Thrust a long the long axis of the station (i.e. a Progress or ATV docked on the end of Zvezda firing rearward facing engines) is pretty close to the CG, and AFAIK this is the preferred configuration to do reboosts.

thanks hop

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