Flight Path Angle-Math Question

Status
Not open for further replies.
K

kyle_baron

Guest
I would like to know the STS-124 Discovery flight path angle, right before SRB seperation.&nbsp; I thought I could figure it out (I didn't) with the 2 pieces of information:&nbsp; 22mi. high and 23mi. down range.&nbsp; Use&nbsp;Pythagorean theorem to find the hypotenuse.&nbsp; Make a right triangle out of it, and use&nbsp; a trigonometric function (like cosine).&nbsp; The answer should be around 45 Deg. (I would think).&nbsp; Can anyone tell me the correct formula, and/or answer?&nbsp; Thanks. <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

C

Cygnus_2112

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I would like to know the STS-124 Discovery flight path angle, right before SRB seperation.&nbsp; I thought I could figure it out (I didn't) with the 2 pieces of information:&nbsp; 22mi. high and 23mi. down range.&nbsp; Use&nbsp;Pythagorean theorem to find the hypotenuse.&nbsp; Make a right triangle out of it, and use&nbsp; a trigonometric function (like cosine).&nbsp; The answer should be around 45 Deg. (I would think).&nbsp; Can anyone tell me the correct formula, and/or answer?&nbsp; Thanks. <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>That isn't the "flight path angle" &nbsp; Flight path angle is the attitude of the vehicle in relation to the horizon&nbsp;</p>

S

shuttle_guy

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;That isn't the "flight path angle" &nbsp; Flight path angle is the attitude of the vehicle in relation to the horizon&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>Yes, I think that is what he was talking about. </p> <div class="Discussion_UserSignature"> </div>

C

Cygnus_2112

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I would like to know the STS-124 Discovery flight path angle, right before SRB seperation.&nbsp; I thought I could figure it out (I didn't) with the 2 pieces of information:&nbsp; 22mi. high and 23mi. down range.&nbsp; Use&nbsp;Pythagorean theorem to find the hypotenuse.&nbsp; Make a right triangle out of it, and use&nbsp; a trigonometric function (like cosine).&nbsp; The answer should be around 45 Deg. (I would think).&nbsp; Can anyone tell me the correct formula, and/or answer?&nbsp; Thanks. <br /> Posted by kyle_baron</DIV></p><p>Yes, at that point (if you have the right data), the shuttle has gone as high as it has gone downrange and that would be a 45 angle from the launch site.&nbsp; </p><p>&nbsp;</p><p>If you are trying to translate this to Ares I, it won't work.&nbsp; Ares I will have different requirements and&nbsp; would have steeper trajectory angle*</p><p>&nbsp;</p><p>* I belive that is the term you are looking for&nbsp;</p>

M

MeteorWayne

Guest
Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Yes, at that point (if you have the right data), the shuttle has gone as high as it has gone downrange and that would be a 45 angle from the launch site.&nbsp; &nbsp;If you are trying to translate this to Ares I, it won't work.&nbsp; Ares I will have different requirements and&nbsp; would have steeper trajectory angle*&nbsp;* I belive that is the term you are looking for&nbsp; <br />Posted by Cygnus_2112</DIV><br /><br />However, that is the cumulative angle, not the angle at the time. All launch vehicles go nearly straight up (to get above as much of the atmosphere as possibe) before tilting over (to gain orbital velocity), so the current thrust angle does not maych the angle since launch.&nbsp; <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

Q

qso1

Guest
<p><font color="#800080">I would like to know the STS-124 Discovery flight path angle, right before SRB seperation.&nbsp; I thought I could figure it out (I didn't) with the 2 pieces of information:&nbsp; 22mi. high and 23mi. down range.&nbsp; Use&nbsp;Pythagorean theorem to find the hypotenuse.&nbsp; Make a right triangle out of it, and use&nbsp; a trigonometric function (like cosine).&nbsp; The answer should be around 45 Deg. (I would think).&nbsp; Can anyone tell me the correct formula, and/or answer?&nbsp; Thanks. Posted by kyle_baron</font></p><p>I've not seen any reliable graphics showing the shuttles ascent trajectory and have had to formulate my own based on the altitude and down range distance at SRB sep. I get approx 45 degree angle. The thrust vector would have to be at about this angle to be at this altitude and distance.</p><p>I graphed this out and found the shuttle would have to begin the pitch down to 45 degrees fairly early in flight to maintain that pitch at SRB sep. The reason, looking at my graph you'll notice a square at the top left corner with 20 on either side. 20 miles up and 20 miles downrange for simplicity.</p><p>Any vehicle following this trajectory would follow a 45 degree angle but would also have to be launched at that angle.</p><p>What appears to actually happen is that the vehicle begins to tilt just after the 120 degree verticle axial roll so that it will be at 45 degrees give or take several degrees when it reaches the altitude and downrange distance for SRB sep. The red line in the chart shows what is probably closest to an actual ascent profile.</p>Liftoff, roll, climbout, and gradual pitchdown occur nearly vertically within the first five to eight miles of ascent. Anyone who has ever witnessed a shuttle launch knows the vehicle does not sharply pitch down very soon. But by SRB sep, it is apparent from the ground that a 45 degree pitchdown (+/- 10 deg altitude and downrange distant dependant) has occured.<br /> <img src="http://sitelife.space.com/ver1.0/Content/images/store/6/13/56684df4-aba2-440b-8dc1-0c929084c6e6.Medium.jpg" alt="" /> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

K

kimmern123

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I would like to know the STS-124 Discovery flight path angle, right before SRB seperation.&nbsp; I thought I could figure it out (I didn't) with the 2 pieces of information:&nbsp; 22mi. high and 23mi. down range.&nbsp; Use&nbsp;Pythagorean theorem to find the hypotenuse.&nbsp; Make a right triangle out of it, and use&nbsp; a trigonometric function (like cosine).&nbsp; The answer should be around 45 Deg. (I would think).&nbsp; Can anyone tell me the correct formula, and/or answer?&nbsp; Thanks. Posted by kyle_baronI've not seen any reliable graphics showing the shuttles ascent trajectory and have had to formulate my own based on the altitude and down range distance at SRB sep. I get approx 45 degree angle. The thrust vector would have to be at about this angle to be at this altitude and distance.I graphed this out and found the shuttle would have to begin the pitch down to 45 degrees fairly early in flight to maintain that pitch at SRB sep. The reason, looking at my graph you'll notice a square at the top left corner with 20 on either side. 20 miles up and 20 miles downrange for simplicity.Any vehicle following this trajectory would follow a 45 degree angle but would also have to be launched at that angle.What appears to actually happen is that the vehicle begins to tilt just after the 120 degree verticle axial roll so that it will be at 45 degrees give or take several degrees when it reaches the altitude and downrange distance for SRB sep. The red line in the chart shows what is probably closest to an actual ascent profile.Liftoff, roll, climbout, and gradual pitchdown occur nearly vertically within the first five to eight miles of ascent. Anyone who has ever witnessed a shuttle launch knows the vehicle does not sharply pitch down very soon. But by SRB sep, it is apparent from the ground that a 45 degree pitchdown (+/- 10 deg altitude and downrange distant dependant) has occured. <br /> Posted by qso1</DIV></p><p>&nbsp;</p><p>At SRB-burnout the vehicle's attitude&nbsp;relative&nbsp;to&nbsp;the horizon (theta-angle) is actually not&nbsp;more than around 18-20&nbsp;degrees pitch up +/-&nbsp;a couple of&nbsp;degrees.&nbsp;</p>

Q

qso1

Guest
<p><font color="#800080">At SRB-burnout the vehicle's attitude&nbsp;relative&nbsp;to&nbsp;the horizon (theta-angle) is actually not&nbsp;more than around 18-20&nbsp;degrees pitch up +/-&nbsp;a couple of&nbsp;degrees. Posted by kimmern123</font></p><p>I can see that being possible if I understood your theta angle correctly. Much of the climbout would be at 45 degrees but at SRB sep...the angle would be steeper by my calcs which are opposite of your. My pitch down angle is based on the shuttle being at 0 degrees at liftoff...totally vertical. Shuttle angle 90 degrees when its payload bay lengthwise is exactly parallel to the horizon.</p><p>In fact, while working on the chart...I had an angle of 60 degrees and rejected it. And to translate your numbers...they would correspond to 68-70 degrees (Shuttle PLB length nearly aligned with earths surface) again, if I understood you correctly.</p><p><br /> <img src="http://sitelife.space.com/ver1.0/Content/images/store/11/5/2bd11d55-fd01-4ea0-a5e4-51d61cd426b6.Medium.jpg" alt="" /><br />&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

K

kimmern123

Guest
That looks correct <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" />

M

MeteorWayne

Guest
Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That looks correct <br />Posted by kimmern123</DIV><br /><br />Sure would be nice to have some real numbers to work with, instead of speculation.... <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

Q

qso1

Guest
<p>If you find any, let me know. NASA has never to my knowledge published a detailed and scaled shuttle or any other LV trajectory for that matter. One of the things I go by here is the visuals. What can be seen from the ground and what NASA SRB separation graphics show. Of course, ground observation has not been that effective at precisely determining the shuttles angle at SRB sep.</p><p>But in general, I think its safe to say the shuttle is pitched down substantially when the SRBs drop off. And that there is still some pitching to do to be at the proper attitude for OMS 1. Or direct insertion. Maybe SG or DrRocket knows where to getv detailed info.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

Q

qso1

Guest
<p><font color="#800080">That looks correct Posted by kimmern123</font></p><p>Did you by chance, see this on some official NASA documents? I would think that 18-20 degree pitch down would be applicaple to the two oms burn orbital insertion while higher angles could be utilized on direct ascent trajectories. Like MW says, were basically speculating, maybe we can see if our speculations are right.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I would like to know the STS-124 Discovery flight path angle, right before SRB seperation.&nbsp; I thought I could figure it out (I didn't) with the 2 pieces of information:&nbsp; 22mi. high and 23mi. down range.&nbsp; Use&nbsp;Pythagorean theorem to find the hypotenuse.&nbsp; Make a right triangle out of it, and use&nbsp; a trigonometric function (like cosine).&nbsp; The answer should be around 45 Deg. (I would think).&nbsp; Can anyone tell me the correct formula, and/or answer?&nbsp; Thanks. <br />Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>Thanks everyone!&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" />&nbsp; Nice graphics qso1.&nbsp; Ok Jim, Trajectory Angle it is.&nbsp; But, I still would like to know the math functions involved.</p><p>&nbsp;</p><p>The Lift-off anouncer gives time, altitude, and down range data.&nbsp; I would think that an accurate graph could be made before, and after SRB seperation, for the trajectory angles, involved.</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

Q

qso1

Guest
<p><font color="#800080">Thanks everyone!&nbsp; &nbsp; Nice graphics qso1.&nbsp; Ok Jim, Trajectory Angle it is.&nbsp; But, I still would like to know the math functions involved.&nbsp;The Lift-off anouncer gives time, altitude, and down range data.&nbsp; I would think that an accurate graph could be made before, and after SRB seperation, for the trajectory angles, involved. Posted by kyle_baron</font></p><p>Thanks, glad you liked the graphics. I'm sure NASA has an accurate graph of the trajectories of each shuttle mission. Its probably just one of those things that the PR people dont think the general public would care to see.The PR folks maybe thinking the public will be sufficiently informed with simpler graphics. Whatever it is, I'd like to see some detailed graphics myself.</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

S

SpaceKiwi

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'><font color="#3366ff">If you find any, let me know. NASA has never to my knowledge published a detailed and scaled shuttle or any other LV trajectory for that matter. <br /></font><strong>Posted by qso1</strong></DIV></p><p>&nbsp;</p><p>Hi Guys, I haven't had a chance to read the following document properly, but you may find it pertinent to your discussion.&nbsp; As best I can see it describes the environment at SRB sep, with a focus on the design and performance of the sep motors.&nbsp; I'm assuming there's some data in there outlining the basic vehicle profile at SRB sep.&nbsp; Anyway, here is the link ... it's a pdf file</p><p>http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760006102_1976006102.pdf</p><p>&nbsp;</p><p>SK&nbsp; <img src="http://sitelife.space.com/ver1.0/Content/images/store/6/11/f6cb650e-25bf-4057-8b61-787938bf4537.Medium.gif" alt="" /></p> <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

Q

qso1

Guest
<p>I'll check it out next chance I get to reboot. I just re-installed my pdf software but have to restart for it to be effective. Thanks for the link. It probably will have data I can translate graphically.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Hi Guys, I haven't had a chance to read the following document properly, but you may find it pertinent to your discussion.&nbsp; As best I can see it describes the environment at SRB sep, with a focus on the design and performance of the sep motors.&nbsp; I'm assuming there's some data in there outlining the basic vehicle profile at SRB sep.&nbsp; Anyway, here is the link ... it's a pdf filehttp://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760006102_1976006102.pdfSK <br />Posted by SpaceKiwi</DIV></p><p>&nbsp;</p><p>Thank you for the link.&nbsp; I'm not really qualified to analyze the data, but from what I learned in this thread:&nbsp; The Flight Path Angle of the SRB's at seperation (approx. 26mi.) is 30 Deg.&nbsp; to the horizon.&nbsp; As opposed to the Trajectory Angle of the Shuttle, at SRB seperation being roughly 45 Deg. to Cape Canaveral.&nbsp; Someone please correct me if I'm wrong.</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

Q

qso1

Guest
<p><font color="#800080">Thank you for the link.&nbsp; I'm not really qualified to analyze the data, but from what I learned in this thread:&nbsp; The Flight Path Angle of the SRB's at seperation (approx. 26mi.) is 30 Deg.&nbsp; to the horizon.&nbsp; As opposed to the Trajectory Angle of the Shuttle, at SRB seperation being roughly 45 Deg. to Cape Canaveral.&nbsp; Someone please correct me if I'm wrong. <br /> Posted by kyle_baron</font></p><p>It'll be awhile before I can check into it but I'll get back to you assuming I figure it out.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

Q

qso1

Guest
<p><font color="#800080">Thank you for the link.&nbsp; I'm not really qualified to analyze the data, but from what I learned in this thread:&nbsp; The Flight Path Angle of the SRB's at seperation (approx. 26mi.) is 30 Deg.&nbsp; to the horizon.&nbsp; As opposed to the Trajectory Angle of the Shuttle, at SRB seperation being roughly 45 Deg. to Cape Canaveral.&nbsp; Someone please correct me if I'm wrong. <br /> Posted by kyle_baron</font></p><p>I've looked at the .pdf file and didn't see anything that really nailed the attitude of the vehicle stack during SRB sep. The closest this document comes is page 19 which on the last few table entries lists latitudes of 28.4891 and so on for the boosters and longitude -80.1250 and so on for the boosters. This latitude and longitude probably reflects the boosters predicted location with respect to KSC which is located at latitude 28&deg;35&prime;06&Prime;N Longitude 80&deg;39&prime;04&Prime;W. Although I dont know why the document shows a negative sign on the longitudinal coords.</p><p>The next line is altitude roughly 140,000 feet (26.5 mi). Then flight path angle of 30 degrees. This would seem to fall between the initial 45 degrees discussed earlier, and the 18-20 degrees shown in my last chart. No mention of how big a difference the angle might be if the insertion is direct or two oms burn.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

K

kimmern123

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Sure would be nice to have some real numbers to work with, instead of speculation.... <br /> Posted by MeteorWayne</DIV></p><p>I asked about&nbsp;the theta angle at SRB-sep over at NASASpaceFlight.com a while ago and got a really extensive answer in one of their Shuttle Q&A-threads. I'll try to dig it up and post a link here.&nbsp;</p>

K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;&nbsp;If you are trying to translate this to Ares I, it won't work.&nbsp;</DIV></p><p>&nbsp;</p><p>I wanted to compare the two vehicles.</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Ares I will have different requirements and&nbsp; would have steeper trajectory angle*&nbsp;* I belive that is the term you are looking for&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>&nbsp;</p><p>Bingo! That's what I wanted to hear.&nbsp; Otherwise, the "Stick" could break in half!<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Thank you for the link.&nbsp; I'm not really qualified to analyze the data, but from what I learned in this thread:&nbsp; The Flight Path Angle of the SRB's at seperation (approx. 26mi.) is 30 Deg.&nbsp; to the horizon.&nbsp; As opposed to the Trajectory Angle of the Shuttle, at SRB seperation being roughly 45 Deg. to Cape Canaveral.&nbsp; Someone please correct me if I'm wrong. <br />Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>Ok, since no one has corrected me, I'm going to take this a step further.&nbsp; Since the Trajectory Angle is roughly 45 Deg. (to the Cape) before SRB seperation, and the Flight Path Angle is 30 Deg. to the ground beneath it;&nbsp; Does this mean that the SRB's thrust vector is NOT ALIGNED with the main engines of the Shuttle?&nbsp; I assume this is because the SSME are gimbled&nbsp; at the 15 Deg. difference?&nbsp; In other words, the Space Shuttle is flying crooked into orbit?<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-undecided.gif" border="0" alt="Undecided" title="Undecided" /><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

C

Cygnus_2112

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Ok, since no one has corrected me, I'm going to take this a step further.&nbsp; Since the Trajectory Angle is roughly 45 Deg. (to the Cape) before SRB seperation, and the Flight Path Angle is 30 Deg. to the ground beneath it;&nbsp; Does this mean that the SRB's thrust vector is NOT ALIGNED with the main engines of the Shuttle?&nbsp; I assume this is because the SSME are gimbled&nbsp; at the 15 Deg. difference?&nbsp; In other words, the Space Shuttle is flying crooked into orbit? <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>Correct.&nbsp; The shuttle engines point through the center of mass of the whole vehicle and are not parallel with the SRB nozzles.&nbsp; The SRB's do the same thing but angle is less.&nbsp; The shuttle does fly at a angle of attack (angle between vehicle and air flow) </p><p>&nbsp;But all this is not related to the difference between flight path and your "trajectory angle.</p><p>&nbsp;</p><p>&nbsp;Below are 3 trajectories. &nbsp;</p><p>The one to the far left is representative of the Atlas II with its balloon tanks. &nbsp; It avoided the dense atmosphere to reduce aero loads.&nbsp; It incurred some gravity losses as a result. &nbsp; The The one to the right left is representative of the Delta II with its more sturdy airframe.&nbsp; It reduces gravity losses with a more shallow angle but incurrs higher aero loads. &nbsp; The trajectory in the middle would be the like shuttle's. &nbsp; This is just an over simplication.&nbsp;&nbsp; </p><p>&nbsp;</p><p><br /> <img src="http://sitelife.space.com/ver1.0/Content/images/store/0/0/508be700-f756-4f75-a07b-5d639083ea53.Medium.jpg" alt="" /><br />&nbsp;</p>

K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Correct.&nbsp; The shuttle engines point through the center of mass of the whole vehicle and are not parallel with the SRB nozzles.&nbsp; The SRB's do the same thing but angle is less.&nbsp; The shuttle does fly at a angle of attack (angle between vehicle and air flow) &nbsp;But all this is not related to the difference between flight path and your "trajectory angle.&nbsp;&nbsp;Below are 3 trajectories. &nbsp;The one to the far left is representative of the Atlas II with its balloon tanks. &nbsp; It avoided the dense atmosphere to reduce aero loads.&nbsp; It incurred some gravity losses as a result. &nbsp; The The one to the right left is representative of the Delta II with its more sturdy airframe.&nbsp; It reduces gravity losses with a more shallow angle but incurrs higher aero loads. &nbsp; The trajectory in the middle would be the like shuttle's. &nbsp; This is just an over simplication.&nbsp;&nbsp; &nbsp; &nbsp; <br />Posted by Cygnus_2112</DIV></p><p>&nbsp;</p><p>It seems to me, that the best trajectory angle for the Ares I, would fall between the Atlas II and Shuttle trajectory angles.&nbsp; This is what you&nbsp;implied in a previous post.&nbsp; What are gravity losses?&nbsp; Speed, or acceleration?<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

Q

qso1

Guest
<p><font color="#800080">Correct.&nbsp; The shuttle engines point through the center of mass of the whole vehicle and are not parallel with the SRB nozzles.&nbsp; The SRB's do the same thing but angle is less.&nbsp; The shuttle does fly at a angle of attack (angle between vehicle and air flow) &nbsp;But all this is not related to the difference between flight path and your "trajectory angle.&nbsp;&nbsp;Below are 3 trajectories. &nbsp;The one to the far left is representative of the Atlas II with its balloon tanks. &nbsp; It avoided the dense atmosphere to reduce aero loads.&nbsp; It incurred some gravity losses as a result. &nbsp; The The one to the right left is representative of the Delta II with its more sturdy airframe.&nbsp; It reduces gravity losses with a more shallow angle but incurrs higher aero loads. &nbsp; The trajectory in the middle would be the like shuttle's. &nbsp; This is just an over simplication. Posted by Cygnus_2112</font></p><p>And in keeping with the spirit of keeping it simple, each of the three trajectories shown would have their own smaller variances depending on mission payload requirements. 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. &nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>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.</em></p> </div>

Status
Not open for further replies.