Ares-1 Orbital Insertion, Trajectory

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kyle_baron

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<p>Ares-1 has a payload problem.&nbsp; With the Orion capsule, and SM, there is between 1,000-2,000 lbs. left for payload.&nbsp; My question is:&nbsp; Can increasing the orbital trajectory from 52 Deg. to 72 Deg. increase the payload capacity of Orion?&nbsp; For reference, Apollo was at 32 Deg.&nbsp; The reason is, that the "Stick" would pass through the lower dense atmosphere, sooner.</p><p>Advantages:</p><p>1.&nbsp; Increased payload capacity (I think).</p><p>2.&nbsp; Less structural stress on the "Stick".</p><p>At a height of 83 mi.&nbsp;the thrusters on the Service Module of Orion, can make the velocity change, for orbital insertion.&nbsp; This is because it is small, light, and traveling at high speed, through practically no atmosphere.</p><p>Disadvantages:</p><p>1.&nbsp; Increased G-load on the astronauts.</p><p>2.&nbsp; Down range issues with the SRB recovery, and 2nd stage falling closer to Florida's coast.</p><p>Astronauts will have to wear G-suits like fighter pilots do.&nbsp; Is that what those orange jump suits are for?&nbsp; Also, astronauts could be seated on air matress seats, custom built by Select Comfort:</p><p>http://en.wikipedia.org/wiki/Sleep_number_bed</p><p>These air matress can handle 1,000 lbs. of force.</p><p>As for the down range issues, the 2nd stage could simply be blown up, after the tank is empty and ejected.&nbsp; This would be similar to the safety measures, used on the shuttle SRB's.</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ares-1 has a payload problem.&nbsp; With the Orion capsule, and SM, there is between 1,000-2,000 lbs. left for payload.&nbsp; My question is:&nbsp; Can increasing the orbital trajectory from 52 Deg. to 72 Deg. increase the payload capacity of Orion?&nbsp; For reference, Apollo was at 32 Deg.&nbsp; The reason is, that the "Stick" would pass through the lower dense atmosphere, sooner.Advantages:1.&nbsp; Increased payload capacity (I think).2.&nbsp; Less structural stress on the "Stick".At a height of 83 mi.&nbsp;the thrusters on the Service Module of Orion, can make the velocity change, for orbital insertion.&nbsp; This is because it is small, light, and traveling at high speed, through practically no atmosphere.Disadvantages:1.&nbsp; Increased G-load on the astronauts.2.&nbsp; Down range issues with the SRB recovery, and 2nd stage falling closer to Florida's coast.Astronauts will have to wear G-suits like fighter pilots do.&nbsp; Is that what those orange jump suits are for?&nbsp; Also, astronauts could be seated on air matress seats, custom built by Select Comfort:http://en.wikipedia.org/wiki/Sleep_number_bedThese air matress can handle 1,000 lbs. of force.As for the down range issues, the 2nd stage could simply be blown up, after the tank is empty and ejected.&nbsp; This would be similar to the safety measures, used on the shuttle SRB's.&nbsp;&nbsp;&nbsp;&nbsp; <br />Posted by kyle_baron</DIV></p><p>I am not sure of the specifics here, but normally trajectories are determined using an optimization code that takes into account the facor that you have noted and the various constraints imposed by safety and other considerations.&nbsp; Generally speaking optimal payloads occur with trajectories that go as nearly straight up as&nbsp;is feasible.&nbsp; I would imagine that all of this has already been taken into account.<br /></p> <div class="Discussion_UserSignature"> </div>
 
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3488

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'><font color="#ff0000">I am not sure of the specifics here, but normally trajectories are determined using an optimization code that takes into account the facor that you have noted and the various constraints imposed by safety and other considerations.&nbsp; Generally speaking optimal payloads occur with trajectories that go as nearly straight up as&nbsp;is feasible.&nbsp; I would imagine that all of this has already been taken into account. <br />Posted by DrRocket</font></DIV></p><p><strong><font size="2">I agree DrRocket. </font></strong></p><p><strong><font size="2">This surely would have been one of the very first things thought off?</font></strong></p><p><strong><font size="2">Andrew Brown.<br /></font></strong></p> <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>
 
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KosmicHero

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I am not sure of the specifics here, but normally trajectories are determined using an optimization code that takes into account the facor that you have noted and the various constraints imposed by safety and other considerations.&nbsp; Generally speaking optimal payloads occur with trajectories that go as nearly straight up as&nbsp;is feasible.&nbsp; I would imagine that all of this has already been taken into account. <br />Posted by DrRocket</DIV><br /><br />The program is called POST (Program for the Optimization of Simulated Trajectories).&nbsp; It's a FORTRAN program developed by NASA and is a pain to use. <div class="Discussion_UserSignature"> kosmichero.wordpress.com </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The program is called POST (Program for the Optimization of Simulated Trajectories).&nbsp; It's a FORTRAN program developed by NASA and is a pain to use. <br />Posted by KosmicHero</DIV></p><p>Post 6-D is one such code.<br /></p> <div class="Discussion_UserSignature"> </div>
 
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chode

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ares-1 has a payload problem.&nbsp; With the Orion capsule, and SM, there is between 1,000-2,000 lbs. left for payload.&nbsp; My question is:&nbsp; Can increasing the orbital trajectory from 52 Deg. to 72 Deg. increase the payload capacity of Orion?&nbsp; For reference, Apollo was at 32 Deg.&nbsp;&nbsp; <br />Posted by kyle_baron</DIV></p><p>Those numbers you quoted are orbital inclinations, which have nothing to do with the angle that the vehicle has during ascent. The orbital inclination is the angle&nbsp;of the orbit of the spacecraft relative to the equator. The ISS is at 52 degrees, so that is what the CEV needs to be able to get to. Apollo was about 32 because that put it in the best orbit to get to the Moon. As has already been suggested, the problem of how your rocket points during its ascent to achieve maximum payload or performance is solved by an optimization program, which I'm sure the designers at NASA use routinely.</p><p>&nbsp;</p><p>Regards</p>
 
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keermalec

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ares-1 has a payload problem.&nbsp; With the Orion capsule, and SM, there is between 1,000-2,000 lbs. left for payload.&nbsp; My question is:&nbsp; Can increasing the orbital trajectory from 52 Deg. to 72 Deg. increase the payload capacity of Orion?&nbsp; For reference, Apollo was at 32 Deg.&nbsp; The reason is, that the "Stick" would pass through the lower dense atmosphere, sooner.Advantages:1.&nbsp; Increased payload capacity (I think).2.&nbsp; Less structural stress on the "Stick".At a height of 83 mi.&nbsp;the thrusters on the Service Module of Orion, can make the velocity change, for orbital insertion.&nbsp; This is because it is small, light, and traveling at high speed, through practically no atmosphere.Disadvantages:1.&nbsp; Increased G-load on the astronauts.2.&nbsp; Down range issues with the SRB recovery, and 2nd stage falling closer to Florida's coast.Astronauts will have to wear G-suits like fighter pilots do.&nbsp; Is that what those orange jump suits are for?&nbsp; Also, astronauts could be seated on air matress seats, custom built by Select Comfort:http://en.wikipedia.org/wiki/Sleep_number_bedThese air matress can handle 1,000 lbs. of force.As for the down range issues, the 2nd stage could simply be blown up, after the tank is empty and ejected.&nbsp; This would be similar to the safety measures, used on the shuttle SRB's.&nbsp;&nbsp;&nbsp;&nbsp; <br />Posted by kyle_baron</DIV></p><p>Anyone correct me if I am wrong, but my understanding is that minimal energy orbital inclination is determined by the latitude of the launch point. For example, when launching from Cape Canaveral, the optimal orbital inclination is 28&deg;. Any other orbital inclination would require additional propellant to make a plane change. Therefore inclining the orbit will not make you save mass, quite the contrary. Also, the higher the latitude of the launch point, the less&nbsp;one takes advantage of the Earth's 0.5 km/s rotational velocity, thus requiring still more propellant.</p><p>Launching the Ares V from the equator onto a 0&deg; orbital plane will maximize payload mass.</p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ares-1 has a payload problem.&nbsp; With the Orion capsule, and SM, there is between 1,000-2,000 lbs. left for payload.&nbsp; My question is:&nbsp; Can increasing the orbital trajectory from 52 Deg. to 72 Deg. increase the payload capacity of Orion?&nbsp; For reference, Apollo was at 32 Deg.&nbsp; The reason is, that the "Stick" would pass through the lower dense atmosphere, sooner.Advantages:1.&nbsp; Increased payload capacity (I think).2.&nbsp; Less structural stress on the "Stick".At a height of 83 mi.&nbsp;the thrusters on the Service Module of Orion, can make the velocity change, for orbital insertion.&nbsp; This is because it is small, light, and traveling at high speed, through practically no atmosphere.Disadvantages:1.&nbsp; Increased G-load on the astronauts.2.&nbsp; Down range issues with the SRB recovery, and 2nd stage falling closer to Florida's coast.Astronauts will have to wear G-suits like fighter pilots do.&nbsp; Is that what those orange jump suits are for?&nbsp; Also, astronauts could be seated on air matress seats, custom built by Select Comfort:http://en.wikipedia.org/wiki/Sleep_number_bedThese air matress can handle 1,000 lbs. of force.As for the down range issues, the 2nd stage could simply be blown up, after the tank is empty and ejected.&nbsp; This would be similar to the safety measures, used on the shuttle SRB's.&nbsp;&nbsp;&nbsp;&nbsp; <br /> Posted by kyle_baron</DIV></p><p>&nbsp;The " orbital trajectory" of 52 Deg is the inclination, not the flight path angle.&nbsp; Inclination is the angle wrt the equator.&nbsp; the ISS is at 51.6 degrees inclination.&nbsp; Increasing the inclination reduces performance. Lunar missions will fly due east from KSC, which provides the minimum inclination of 28.5 degrees from that site</p><p>&nbsp;Flight path angle is variable and is driven by many factors: range safety, aeroloads, thermal loads, g loads, antenna angles, etc, all which affect performance.&nbsp; The Ares trajectory already optimizes these factors to get the highest performance </p>
 
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trailrider

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ares-1 has a payload problem.&nbsp; With the Orion capsule, and SM, there is between 1,000-2,000 lbs. left for payload.&nbsp; My question is:&nbsp; Can increasing the orbital trajectory from 52 Deg. to 72 Deg. increase the payload capacity of Orion?&nbsp; For reference, Apollo was at 32 Deg.&nbsp; The reason is, that the "Stick" would pass through the lower dense atmosphere, sooner.Advantages:1.&nbsp; Increased payload capacity (I think).2.&nbsp; Less structural stress on the "Stick".At a height of 83 mi.&nbsp;the thrusters on the Service Module of Orion, can make the velocity change, for orbital insertion.&nbsp; This is because it is small, light, and traveling at high speed, through practically no atmosphere.Disadvantages:1.&nbsp; Increased G-load on the astronauts.2.&nbsp; Down range issues with the SRB recovery, and 2nd stage falling closer to Florida's coast.Astronauts will have to wear G-suits like fighter pilots do.&nbsp; Is that what those orange jump suits are for?&nbsp; Also, astronauts could be seated on air matress seats, custom built by Select Comfort:http://en.wikipedia.org/wiki/Sleep_number_bedThese air matress can handle 1,000 lbs. of force.As for the down range issues, the 2nd stage could simply be blown up, after the tank is empty and ejected.&nbsp; This would be similar to the safety measures, used on the shuttle SRB's.&nbsp;&nbsp;&nbsp;&nbsp; <br />Posted by kyle_baron</DIV></p><p>As has been stated by others, the higher the orbital inclination with respect to the equator, the more performance is required of the booster, compared to a true equitorial orbit.&nbsp; So far as trajectory optimisation is concerned, as others have stated, the shaping is done by computer modelling taking into account thrust-versus-time profiles, staging points, etc.</p><p>The main problem with the Ares I is that it is so underpowered that compromises with safety and capability of the Orion spacecraft have been and will continue to be made!&nbsp; With any luck at all, Congress may wind up requiring NASA to make changes to insure the success of the VSE, and hopefully we can go to a launch vehicle that makes sense, instead of this latter-day Vanguard rocket! :(&nbsp; Like a Jupiter 120/242 series or something!</p><p>Ad Luna! Ad Ares! Ad Astra!<br /></p>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>As has been stated by others, the higher the orbital inclination with respect to the equator, the more performance is required of the booster, compared to a true equitorial orbit.&nbsp; So far as trajectory optimisation is concerned, as others have stated, the shaping is done by computer modelling taking into account thrust-versus-time profiles, staging points, etc.The main problem with the Ares I is that it is so underpowered that compromises with safety and capability of the Orion spacecraft have been and will continue to be made!&nbsp; With any luck at all, Congress may wind up requiring NASA to make changes to insure the success of the VSE, and hopefully we can go to a launch vehicle that makes sense, instead of this latter-day Vanguard rocket! :(&nbsp; Like a Jupiter 120/242 series or something!Ad Luna! Ad Ares! Ad Astra! <br />Posted by trailrider</DIV></p><p>If there really is a problem, has a composite case for the SRBs been considered for this mission ?&nbsp; That option has been considered for the STS and it provides an appreciable additional payload.</p> <div class="Discussion_UserSignature"> </div>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If there really is a problem, has a composite case for the SRBs been considered for this mission ?&nbsp; That option has been considered for the STS and it provides an appreciable additional payload. <br /> Posted by DrRocket</DIV></p><p>&nbsp;Bause that negates the whole reason that Ares I exists. </p><p>Ares I is not designed to use any solid motor.&nbsp; It is designed to shuttle SRB hardware. The Ares I booster* is "safe" since it uses a motor that has more than 200 flights and has proven processes.</p><p>&nbsp;A new liquid booster is safer than a new SRM since it is easier to qualify and it can be shutdown.&nbsp; Therefore anything that doesn't use the existing cases is not viable</p><p>&nbsp;A properly designed and optimized first stage would not use SRMs </p>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Bause that negates the whole reason that Ares I exists. Ares I is not designed to use any solid motor.&nbsp; It is designed to shuttle SRB hardware. The Ares I booster* is "safe" since it uses a motor that has more than 200 flights and has proven processes.&nbsp;A new liquid booster is safer than a new SRM since it is easier to qualify and it can be shutdown.&nbsp; Therefore anything that doesn't use the existing cases is not viable&nbsp;A properly designed and optimized first stage would not use SRMs <br />Posted by Cygnus_2112</DIV></p><p>A graphite composite case for the SRB was designed, qualified, stacked and on the pad at Vandenberg for launch with the shuttle system when the Challenger disaster occurred.&nbsp; It even included the 0-ring capture feature that became part of the RSRM.<br /></p> <div class="Discussion_UserSignature"> </div>
 
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scottb50

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>As has been stated by others, the higher the orbital inclination with respect to the equator, the more performance is required of the booster, compared to a true equitorial orbit.&nbsp; So far as trajectory optimisation is concerned, as others have stated, the shaping is done by computer modelling taking into account thrust-versus-time profiles, staging points, etc.The main problem with the Ares I is that it is so underpowered that compromises with safety and capability of the Orion spacecraft have been and will continue to be made!&nbsp; With any luck at all, Congress may wind up requiring NASA to make changes to insure the success of the VSE, and hopefully we can go to a launch vehicle that makes sense, instead of this latter-day Vanguard rocket! :(&nbsp; Like a Jupiter 120/242 series or something!Ad Luna! Ad Ares! Ad Astra! <br /> Posted by trailrider</DIV></p><p>&nbsp;</p><p>Also the Cape sits well above the equator, that a main reason the French went to South America. It uses a lot more propellant to get to a 0 degree orbit the to an optimal orbit from the Cape. &nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
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scottb50

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<p>Ares I is not designed to use any solid motor. ...</p><p>&nbsp;</p><p>Ares one is a Shuttle SRB with an upper stage. I think you are referring the the Ares 5, which uses a liquid stage, as well as SRB's.&nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;The " orbital trajectory" of 52 Deg is the inclination, not the flight path angle.&nbsp; Inclination is the angle wrt the equator.&nbsp; the ISS is at 51.6 degrees inclination.&nbsp; Increasing the inclination reduces performance. Lunar missions will fly due east from KSC, which provides the minimum inclination of 28.5 degrees from that site&nbsp;Flight path angle is variable and is driven by many factors: range safety, aeroloads, thermal loads, g loads, antenna angles, etc, all which affect performance.&nbsp; The Ares trajectory already optimizes these factors to get the highest performance <br />Posted by Cygnus_2112</DIV><br /><br />For a good education on Flight paths, watch an Arienne launch. They have a chart that shows altitude and range (i.e.) the path.</p><p>Basically, all orbital launches are roughly striaght up, so you get above as much of the atmosphere as possible, then and only then, does the craft tilt over so that the thrust adds orbital velocity, nit altitude. In fact, the altitude decreases as the thrust is aligned to produce obital velocity...taking advantage of the "going downhill" part of the equation. It's fun and educational to watch. Too bad NASA doesn't display the same data for a SHuttle Launch. I'd love to see it.</p> <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>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>A graphite composite case for the SRB was designed, qualified, stacked and on the pad at Vandenberg for launch with the shuttle system when the Challenger disaster occurred.&nbsp; It even included the 0-ring capture feature that became part of the RSRM. <br /> Posted by DrRocket</DIV></p><p>That is immaterial&nbsp; for this and inccrrect (nonflight versions were stacked) .&nbsp; Those SRM's had no flight history.&nbsp;&nbsp;&nbsp;That is main basis for the selection of the SRB for the Ares I first stage booster. The FWC SRB is basically a new motor and would have&nbsp; low LOC/LOM numbers&nbsp; </p><p>&nbsp;</p>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ares I is not designed to use any solid motor. ...&nbsp;Ares one is a Shuttle SRB with an upper stage. I think you are referring the the Ares 5, which uses a liquid stage, as well as SRB's.&nbsp; <br /> Posted by scottb50</DIV></p><p>You miss understood.&nbsp; Ares I is not designed to use "any ole" solid motor, but one specifc one, the shuttle SRB.&nbsp;</p>
 
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scottb50

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You miss understood.&nbsp; Ares I is not designed to use "any ole" solid motor, but one specifc one, the shuttle SRB.&nbsp; <br /> Posted by Cygnus_2112</DIV></p><p>Oops, your right Ares I is an SRB, Ares5 is a liquid stage with SRB's attached. I get confused easily these days.&nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;The " orbital trajectory" of 52 Deg is the inclination, not the flight path angle.&nbsp; Inclination is the angle wrt the equator.&nbsp; the ISS is at 51.6 degrees inclination.&nbsp; Increasing the inclination reduces performance. Lunar missions will fly due east from KSC, which provides the minimum inclination of 28.5 degrees from that site&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'></p><p>&nbsp;</p><p>Ok, let me see if I have this correct.&nbsp; As the Earth rotates, the orbit of the space station will pass over Florida.&nbsp; That orbit is 52 Deg. with respect to the equator.&nbsp; At this time, the shuttle would launch in the direction (North-west to South-east for example) to intercept this orbit?</p><p>Another question is, the shuttle follows the Earth's rotation, and gains 1,000 mph. for free?&nbsp; How does that work?&nbsp; The 1,000 mph isn't much compared to the 17,000+ mph needed for orbital insertion.&nbsp; That's like getting only 6% additional speed.</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Flight path angle is variable and is driven by many factors: range safety, aeroloads, thermal loads, g loads, antenna angles, etc, all which affect performance.&nbsp; The Ares trajectory already optimizes these factors to get the highest performance <br />Posted by Cygnus_2112</DIV></p><p>&nbsp;</p><p>Now we get to the main problem for payload performance.&nbsp; "Flight path angle is variable".&nbsp; Say, for example, that range safety, and g-loads are taken care of.&nbsp; My question as before is,&nbsp;does taking a higher flight path angle, increase payload&nbsp;capacity, all other things being equal?&nbsp; Dr. Rocket seems to agree with me, I think.&nbsp;<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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trailrider

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You miss understood.&nbsp; Ares I is not designed to use "any ole" solid motor, but one specifc one, the shuttle SRB.&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>But the problem is that the 5-segment SRM is NOT the same as a Shuttle 4-segment SRB.&nbsp; First, they added the fifth segment.&nbsp; This increases (as is intended) the burning area because the propellant burns from the inside of the grain radially outward.&nbsp; By shaping the grain internally, you can control the burning rate as well as the pressure-time profile...up to a point.&nbsp; But increasing the burning area increases the amount of combustion gases flowing down the center of the grain.&nbsp; This increases the pressure, which also increases the burning rate, if you aren't careful.</p><p>But why increase the burning area in the first place? To get more combustion gas mass flowing per unit time (mass flow rate).&nbsp; The idea is to increase the thrust.&nbsp; But thrust and pressure are proportional to the area across the chamber throat, as well as the exit cone diameter (which is usally designed as some compromise of the pressure at sea level and the pressure at altitude).&nbsp; So, okay, this means you have to have a new nozzle design.</p><p>The SRB's and the SRM's use a flexible nozzle for thrust vector control (TVC), with hydraulics packages controlling actuators that push the nozzle "right and left" for yaw control, and "up and down" for pitch control.&nbsp; On the Shuttle, in order to control roll, the <em>two</em> SRB's deflect the nozzles in opposite directions.&nbsp; But with a SINGLE SRM (the Ares I first stage), you don't have any roll control directly, so you have to add a roll thrust setup.&nbsp; This can be (and is what I understand is being considered or actually has been adopted for the Ares I design) done by using a low-thrust rocket motor with a "hammer-headed" nozzle with a valve in the middle.&nbsp; Since a solid rocket motor, which is what has been discussed, can't be turned on and off, it must continue to burn.&nbsp; So the valve is set up so that when you want NO ROLL at all, the valve exhausts through both nozzles.&nbsp; If you want to roll clockwise, the valve shuts off the one nozzle, and visa versa.&nbsp; Neat!&nbsp; Great system!&nbsp; But you have to have two of them, in case the valve sticks or something.&nbsp; So you've added weight to the SRM.&nbsp; You also may need to use a more robust TVC package, adding weight, and requiring recertification.</p><p>Next, you have the problem of the combustion-induced vibrations that have been in the news.&nbsp; How bad that is hasn't been determined, but there are several ways to control the situation, most of which add weight or degrade performance (by reshaping the grain or doing something to the propellant mixture at the "tail-off" period in the burn profile.</p><p>So we've ONLY done a whole bunch of things to the original SRB design to make it an Ares I 1st stage... All that's necessary is to jack up the NASA logo and slip the new SRM under it!&nbsp; And then change the logo decal! (wacko!)</p><p>For Ares V, in addition to using a pair of 5-segment SRM's (which allows us to delete the roll control), we are having to go to a (IIRC) 10m diameter tank, requiring complete retooling of the Michaud facility!</p><p>So in what way are we "utilizing" a maximum of STS hardward and tooling?</p><p>You COULD use a pair of 4-segment Shuttle SRB's on extended ET, with a pair or three of RS-68 engines on the first stage core vehicle, initially WITHOUT an upper stage, and put a lot more payload into orbit, and without modifying the Shuttle launch pad dramatically.&nbsp; Add some upper stages to a 3 engine 1st stage, and you have something capable of going to the Moon.&nbsp; Of course it would take two launches, in stead of the "1-1/2" Ares I/Ares V scenario.&nbsp; I think it's called DIRECT!</p><p>Ad Luna! Ad Ares! Ad Astra!<br /></p>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Now we get to the main problem for payload performance.&nbsp; "Flight path angle is variable".&nbsp; Say, for example, that range safety, and g-loads are taken care of.&nbsp; My question as before is,&nbsp;does taking a higher flight path angle, increase payload&nbsp;capacity, all other things being equal?&nbsp; Dr. Rocket seems to agree with me, I think.&nbsp; <br /> Posted by kyle_baron</DIV></p><p>&nbsp;Not necessarily true.&nbsp; It depends on the thrust profile and mass ratio of the vehicle. If there was no air or mountains, a zero flight path angle would be better. </p>
 
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Cygnus_2112

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> <br /><p>1. Ok, let me see if I have this correct.&nbsp; As the Earth rotates, the orbit of the space station will pass over Florida.&nbsp; That orbit is 52 Deg. with respect to the equator.&nbsp; At this time, the shuttle would launch in the direction (North-west to South-east for example) to intercept this orbit?</p><p>2.&nbsp; Another question is, the shuttle follows the Earth's rotation, and gains 1,000 mph. for free?&nbsp; How does that work?&nbsp; The 1,000 mph isn't much compared to the 17,000+ mph needed for orbital insertion.&nbsp; That's like getting only 6% additional speed.</p><p> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>&nbsp;1. &nbsp;yes, the shuttle launches to a 37 degree azimuth.</p><p>&nbsp;2. &nbsp;It is for free. &nbsp;sitting on the ground, the shuttle already has a inertial velocity. &nbsp;orbital velocity is independent of earth's rotation </p><p>6% is still something&nbsp;</p>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That is immaterial&nbsp; for this and inccrrect (nonflight versions were stacked) .&nbsp; Those SRM's had no flight history.&nbsp;&nbsp;&nbsp;That is main basis for the selection of the SRB for the Ares I first stage booster. The FWC SRB is basically a new motor and would have&nbsp; low LOC/LOM numbers&nbsp; &nbsp; <br />Posted by Cygnus_2112</DIV></p><p>While it is true that the FWC case had no flight history it was scheduled for use on STS-62-A and the design had been tested and qualified for flight.<br /></p> <div class="Discussion_UserSignature"> </div>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>While it is true that the FWC case had no flight history it was scheduled for use on STS-62-A and the design had been tested and qualified for flight. <br /> Posted by DrRocket</DIV></p><p>&nbsp;Which has no bearing on its use for the Ares I first stage booster.&nbsp; The FWC SRB qualifications for the STS are not applicable for Ares I. &nbsp; </p><p>And actually after Challenger, the FWC SRB was "unqualified" for flight, independently of the status of SLC-6.&nbsp; </p>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Which has no bearing on its use for the Ares I first stage booster.&nbsp; The FWC SRB qualifications for the STS are not applicable for Ares I. &nbsp; And actually after Challenger, the FWC SRB was "unqualified" for flight, independently of the status of SLC-6.&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>You seem to be deliberately being picky.&nbsp; The point is that there are technologies available that can be used to increase the capabilities of the SRMs if there is a need to do so.</p><p>During the studies to improve shuttle payload capability for ISS payloads the use of a composite case was again evaluated.&nbsp; It was shown that a composite case could be produced that would duplicate the dynamic "twang" of the steel cases and provide a significant additional payload.&nbsp; Another possibility was the use of a more modern HTPB propellant formulation in place of the PBAN formulation used in the current SRMs.&nbsp; That would provide a little better ISP and also increase performance.&nbsp;&nbsp; It would also permit vacuum mixing of the propellant which would in turn provide better control of voids.</p><p>With any design change the changes would need to be analyzed and tested to qualify them prior to flight, but these changes are well--understood, of known low risk, and use manufacturing technologies that are in place.&nbsp; These technologies are on other large U.S. boosters -- Titan IV B, Delta II, Delta III, Pegasus to name a few.&nbsp; <br /></p> <div class="Discussion_UserSignature"> </div>
 
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