Flight Path Angle-Math Question

Cygnus_2112 · Jun 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> The shuttle path for example will appear slightly different on a direct insertion OMS burn mission than it would for a two oms burn mission.   Posted by qso1</DIV> Not really.  that only affects the end condtion.  Most of the trajectory is the same.

qso1 · Jun 7, 2008

I've seen direct insertion and standard shuttle missions at launch and there is a noticeable difference in the climbout. And your probably right, it may not mean anything but right now, I want to see some actual NASA trajectory data that shows exactly how this works before reaching any further conclusions.  <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

Cygnus_2112 · Jun 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I've seen direct insertion and standard shuttle missions at launch and there is a noticeable difference in the climbout. And your probably right, it may not mean anything but right now, I want to see some actual NASA trajectory data that shows exactly how this works before reaching any further conclusions.  Posted by qso1</DIV> The only thing one would be able to discern from watching a launch is the inclination.  For the shuttle, the trajectory from launch to SRB sep is exactly the same

qso1 · Jun 7, 2008

I agree there, I eyeball the inclination from watching and I did say what I saw may not mean anything. I said that because I'm mainly working off my memory which isn't so hot anyway, I need to verify it graphically with NASA documents.I'm sure you probably know this already but nothing is exactly the same. I just would like to go ahead and see a NASA trajectory schematic of some kind to see where we all are right, wrong, or pretty close. Unfortunately, it appears there is no easy way to get such a schematic.I also wanted to see it in a form similar to what I would do if I made a graphic of one based on all the numbers I would need.  <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

kyle_baron · Jun 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> Unfortunately, it appears there is no easy way to get such a schematic.I also wanted to see it in a form similar to what I would do if I made a graphic of one based on all the numbers I would need.  Posted by qso1</DIV> These are some of the numbers I got from the "You Tube" video of STS-124:Altitude:  Down Range:5            8.5 22          23  (45 Deg. Trajectory before SRB seperation)37          50  (after SRB seperation)52          10062          170 It would appear that after SRB seperation, the trajectory angle flattens out considerably. <div class="Discussion_UserSignature"> </div>

Cygnus_2112 · Jun 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>  It would appear that after SRB seperation, the trajectory angle flattens out considerably. Posted by kyle_baron</DIV>That is true for most orbital launches regardless of vehicle.  Altitude is easy to achieve, velocity is the hard part

qso1 · Jun 7, 2008

It would appear that after SRB seperation, the trajectory angle flattens out considerably. Posted by kyle_baronThe only thing thats still a little bit of a mystery is the 45 degree angle going to 22 degrees by the time the SRBs separate but other than that. The data is fairly close to what I imagines and like Cygnus2112 says...all LVs are about the same with regard to ascent profiles.  <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

MeteorWayne · Jun 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>It would appear that after SRB seperation, the trajectory angle flattens out considerably. Posted by kyle_baronThe only thing thats still a little bit of a mystery is the 45 degree angle going to 22 degrees by the time the SRBs separate but other than that. The data is fairly close to what I imagines and like Cygnus2112 says...all LVs are about the same with regard to ascent profiles.  Posted by qso1</DIV> It's really not a mystery. the idea is to get through the atmosphere ASAP. From what I would imagine, you go up quick then tilt over more and more as you go along (height vs velocity. IIRC, Max Q (dynamic pressure ) is about 70 seconds in ("go at throttleup") after that you can work on gaining velocity. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

qso1 · Jun 7, 2008

It's really not a mystery. the idea is to get through the atmosphere ASAP. From what I would imagine, you go up quick then tilt over more and more as you go along (height vs velocity. IIRC, Max Q (dynamic pressure ) is about 70 seconds in ("go at throttleup") after that you can work on gaining velocity. Posted by MeteorWayneMystery was a bad choice of words on my part and I understand all what you mentioned but you would actually get above the atmosphere faster if you were at a higher climbout angle. If you pitch down sooner, relative to the horizon...your increasing your forward ground track and remaining in the atmosphere that much longer I would think.I graphed it out and the yellow track shows that the higher pitch angle reaches higher altitude faster than the lower (White) pitch angle trajectory. The numbers given simply indicate the shuttle does not have to go quite as high as I thought previously before pitching to the 20 some odd degrees it needs to be at for SRB sep. <img src="http://sitelife.space.com/ver1.0/Content/images/store/11/5/eb9c6ae0-84a4-44d8-85fd-954cab2e0c81.Medium.jpg" alt="" />   <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

kyle_baron · Jun 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> Replying to:<div class="Discussion_PostQuote">  It would appear that after SRB seperation, the trajectory angle flattens out considerably. Posted by kyle_baron</div> That is true for most orbital launches regardless of vehicle.  Altitude is easy to achieve, velocity is the hard part Posted by Cygnus_2112</DIV> Ok, but will it be true for Ares I which will have to accomodate additional payload?  Why wouldn't the steeper trajectory work better with more payload? <div class="Discussion_UserSignature"> </div>

qso1 · Jun 7, 2008

Ok, but will it be true for Ares I which will have to accomodate additional payload?  Why wouldn't the steeper trajectory work better with more payload? Posted by kyle_baronMakes sense to me but until we can see detail data from NASA, I doubt anyone can know for certain what Ares ascent parameters will be. I did a book years ago (Never able to pub it) that featured a section on the shuttle RTLS and at SRB sep, I have the shuttle at probably 45 degrees pitch down.Thats was when I did my search for detail data to confirm what I thought might be the actual angle. I had to guess and did essentially the same thing you did when trying to figure out what the pitch angle should be. Nice thing about 3D illustration is the ability to scale...even distances in hundreds of miles.The image was scaled as to downrange distance and altitude. The shuttle is pitched down which can be easily done and to tenths of a degree if one wants. <img src="http://sitelife.space.com/ver1.0/Content/images/store/5/5/1530e8f1-d814-440f-a59c-5eb76c6e0198.Medium.jpg" alt="" />   <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

Cygnus_2112 · Jun 8, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> Ok, but will it be true for Ares I which will have to accomodate additional payload?  Why wouldn't the steeper trajectory work better with more payload? Posted by kyle_baron</DIV> Can't answer that.  There are many other factors which will determine the trajectory.

kyle_baron · Jun 8, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> Replying to:<div class="Discussion_PostQuote"> Ok, but will it be true for Ares I which will have to accomodate additional payload?  Why wouldn't the steeper trajectory work better with more payload? Posted by kyle_baron</div>  Can't answer that.  There are many other factors which will determine the trajectory.   </DIV> Oh, come on now, why play it safe?  Why not speculate?  <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" />  At what trajectories do you think Ares I should be at, before and after SRB seperation?  Say G-Loads on the astronauts aren't a problem, and down range issues (we blow up the 2nd stage) isn't an issue.    <div class="Discussion_UserSignature"> </div>

kyle_baron · Jun 8, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>The image was scaled as to downrange distance and altitude. The shuttle is pitched down which can be easily done and to tenths of a degree if one wants.   Posted by qso1</DIV> I LOVE those images, keep'em comming.   This latest one is very interesting, from LEO, I assume. <div class="Discussion_UserSignature"> </div>

qso1 · Jun 9, 2008

I LOVE those images, keep'em comming.   This latest one is very interesting, from LEO, I assume. Posted by kyle_baronThanks, glad you liked the images. The latest one would be from the vantage point of a camera near the shuttle during SRB sep if you could have a free flying camera go along for the ascent.  <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

stanwhite · Jun 11, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I LOVE those images, keep'em comming.   This latest one is very interesting, from LEO, I assume. Posted by kyle_baronThanks, glad you liked the images. The latest one would be from the vantage point of a camera near the shuttle during SRB sep if you could have a free flying camera go along for the ascent.  Posted by qso1</DIV>Here is a similar math question, one that it seems NASA has never addressed. What are the advantages of launching at a mountaintop space pad? 1) 30% less air resistance2) MaxQ is less a limit, if any3) The rocket plume is better, a big plus for TSTOHere is some background  http://www.g2mil.com/high.htm

Cygnus_2112 · Jun 11, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Here is a similar math question, one that it seems NASA has never addressed. What are the advantages of launching at a mountaintop space pad? 1) 30% less air resistance2) MaxQ is less a limit, if any3) The rocket plume is better, a big plus for TSTOHere is some background  http://www.g2mil.com/high.htm Posted by stanwhite</DIV> They have been answered by the fact there isn't a mountain top pad1.  No US mountains on the coastlines2.  Logistics of building and maintaining a facility on a mountain 3.  problems of getting a large vehicle to the mountain top The link is nothing but a kook site

qso1 · Jun 12, 2008

Here is a similar math question, one that it seems NASA has never addressed. What are the advantages of launching at a mountaintop space pad? 1) 30% less air resistance2) MaxQ is less a limit, if any3) The rocket plume is better, a big plus for TSTOHere is some background  http://www.g2mil.com/high.htm Posted by stanwhiteI would expect that there would be an advantage if the mountain is high enough. Problem is, as the previous post mentions, the really high mountains are logistically difficult to provide support for. Problem one being range safety. Range safety was the primary reason for selection of Cape Canaveral in the early days of rocket launching when White Sands missile range had been outgrown. White Sands was a desert location for the most part but they had to relocate when missiles exceeded the range safety limitations.Mauna Kea in Hawaii would be an ideal candidate but much of that high altitude real estate goes for observatories. Hawaii would probably be pushing the edge of practical logistical support also. TSTO would probably benefit if a system like Rutans becomes available and practical in time.This because the carrier aircraft would operate no differently from a range safety standpoint than commercial airlines  <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

stanwhite · Jun 12, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Here is a similar math question, one that it seems NASA has never addressed. What are the advantages of launching at a mountaintop space pad? 1) 30% less air resistance2) MaxQ is less a limit, if any3) The rocket plume is better, a big plus for TSTOHere is some background  http://www.g2mil.com/high.htm Posted by stanwhiteI would expect that there would be an advantage if the mountain is high enough. Problem is, as the previous post mentions, the really high mountains are logistically difficult to provide support for. Problem one being range safety. Range safety was the primary reason for selection of Cape Canaveral in the early days of rocket launching when White Sands missile range had been outgrown. White Sands was a desert location for the most part but they had to relocate when missiles exceeded the range safety limitations.Mauna Kea in Hawaii would be an ideal candidate but much of that high altitude real estate goes for observatories. Hawaii would probably be pushing the edge of practical logistical support also. TSTO would probably benefit if a system like Rutans becomes available and practical in time.This because the carrier aircraft would operate no differently from a range safety standpoint than commercial airlines  Posted by qso1</DIV>I was more interested in the math aspect, since the Russians launch from much higher. Keep in mind that the flatlands at Tonopah are at 6000 feet, and Chlie has a plain at 14,000 feet. I won't discuss the impractical logistics of moving the SRBs from Florida to Utah and back.I realize that some think any website that is not nasa.gov is a "kook" site, but then such persons do not realize that the tallest mountain in the World is in the USA, next to the ocean. Tallest, not highest. May I suggest that you read a website before you demean it with childish insults. You will learn things, if that is possible.Back to the math question, the link poses some general calculations, on such "kooky" things like rocket plumes. Anyone here want to address the math?

qso1 · Jun 12, 2008

I was more interested in the math aspect, since the Russians launch from much higher. Keep in mind that the flatlands at Tonopah are at 6000 feet, and Chlie has a plain at 14,000 feet. I won't discuss the impractical logistics of moving the SRBs from Florida to Utah and back.In that case, I wont discuss the impractical logistics of suggesting mountain launch sites for a system about to be retired. I realize that some think any website that is not nasa.gov is a "kook" site, but then such persons do not realize that the tallest mountain in the World is in the USA, next to the ocean. Tallest, not highest. May I suggest that you read a website before you demean it with childish insults.May I suggest that when you respond to a post, you check what your responding to. I wasn't the one who criticized the website. I think your thinking of Cygnus2112. And if that is the Pacific ocean which it would have to be...then throw practicallity out the window.When you launch from the Pacific side of the coast into a roughly equatorial orbit, you have very little payload to orbit mass advantage as you do when you launch from the Atlantic where the launch vehicle gains an almost 1,000 mph velocity advantage provided by earths rotation. Last I checked, there were no tall...or high mountains on the Atlantic ocean side of U.S. You will learn things, if that is possible.Back to the math question, the link poses some general calculations, on such "kooky" things like rocket plumes. Anyone here want to address the math? Posted by stanwhiteI'm already aware of calculations pertaining to rockets although I'd be the first to admit I'm not the best at actually recalling formulas off the top of my head. I didn't address the actual math for that reason but if your above 30% of the atmosphere when launching from a mountain top, it stands to reason that you will benefit by somewhere around that much.The problem is, tradeoffs. Will the benefits outweigh the logistical costs? For the shuttle, the answer is an obvious no regardless of the logistics of SRB transport simply because the shuttle is a very expensive system to operate anyway. You wont realize much in savings by moving launch operations to a mountain top where you'd have to build processing facilities from the ground up, including one tall enough (Not necessarily VAB tall) to enable stacking of the vehicle.Not to mention the shuttle is about to be retired.As I mentioned in my previous post, mountain launches may be something well worth considering for any company or NASA if they are planning to develop a TSTO. NASA is pretty much out of the cheap access to space business but the private sector is just about to enter that business and if mountain launching proves practical to the company that may wish to incorporate it, then it will be adapted. <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

Cygnus_2112 · Jun 12, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I was more interested in the math aspect, since the Russians launch from much higher. Keep in mind that the flatlands at Tonopah are at 6000 feet, and Chlie has a plain at 14,000 feet. I won't discuss the impractical logistics of moving the SRBs from Florida to Utah and back.I realize that some think any website that is not nasa.gov is a "kook" site, but then such persons do not realize that the tallest mountain in the World is in the USA, next to the ocean. Tallest, not highest. May I suggest that you read a website before you demean it with childish insults. You will learn things, if that is possible.Back to the math question, the link poses some general calculations, on such "kooky" things like rocket plumes. Anyone here want to address the math? Posted by stanwhite</DIV> It has nothing to do with nasa.gov, there are many none NASA websites that a good, just not this one.  I read the website and stand behind my comments.  Baikonur, the Russian space center for manned mission isn't "higher".  It is only about 100 meters above sea level, no real advantage.The plume issue isn't simple math.  It just means a nozzle doesn't have to be designed to operate from sea level to altitube but can be optimized for operation at altitude, which means it can increase the efficiency of the engineAnyways tallest doen't matter, highest doe.

Flight Path Angle-Math Question

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