Propulsion Performance - Revision history

https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?action=history&feed=atom&title=Propulsion_Performance Propulsion Performance - Revision history 2026-05-02T13:54:35Z Revision history for this page on the wiki MediaWiki 1.41.1 https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=2933&oldid=prev Tshhmon at 21:49, 23 April 2024 2024-04-23T21:49:26Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:49, 23 April 2024</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l95">Line 95:</td> <td colspan="2" class="diff-lineno">Line 95:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Just what physically corresponds to that 'characteristic velocity' we call Isp is different in different propulsion systems -- but for performance purposes, it doesn't matter. Whether it be fuel in an airbreathing engine, propellant in a rocket, or reaction mass being expelled from some other energy supply onboard, if you're using something up to get your propulsion, Isp defines how much propulsion you get for each unit of consumed mass.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Just what physically corresponds to that 'characteristic velocity' we call Isp is different in different propulsion systems -- but for performance purposes, it doesn't matter. Whether it be fuel in an airbreathing engine, propellant in a rocket, or reaction mass being expelled from some other energy supply onboard, if you're using something up to get your propulsion, Isp defines how much propulsion you get for each unit of consumed mass.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[Category:<del style="font-weight: bold; text-decoration: none;">Spacecraft </del>& Infrastructure‏‎]][[Category:Propulsion]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[Category:<ins style="font-weight: bold; text-decoration: none;">Transportation </ins>& Infrastructure‏‎]][[Category:Propulsion<ins style="font-weight: bold; text-decoration: none;">]][[Category:Transportation</ins>]]</div></td></tr> </table>

Tshhmon https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=2530&oldid=prev Tshhmon at 19:21, 4 April 2024 2024-04-04T19:21:00Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:21, 4 April 2024</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l95">Line 95:</td> <td colspan="2" class="diff-lineno">Line 95:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Just what physically corresponds to that 'characteristic velocity' we call Isp is different in different propulsion systems -- but for performance purposes, it doesn't matter. Whether it be fuel in an airbreathing engine, propellant in a rocket, or reaction mass being expelled from some other energy supply onboard, if you're using something up to get your propulsion, Isp defines how much propulsion you get for each unit of consumed mass.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Just what physically corresponds to that 'characteristic velocity' we call Isp is different in different propulsion systems -- but for performance purposes, it doesn't matter. Whether it be fuel in an airbreathing engine, propellant in a rocket, or reaction mass being expelled from some other energy supply onboard, if you're using something up to get your propulsion, Isp defines how much propulsion you get for each unit of consumed mass.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Spacecraft & Infrastructure‏‎]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Spacecraft & Infrastructure‏‎<ins style="font-weight: bold; text-decoration: none;">]][[Category:Propulsion</ins>]]</div></td></tr> </table>

Tshhmon https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=1540&oldid=prev Lwcamp at 19:17, 26 August 2022 2022-08-26T19:17:25Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:17, 26 August 2022</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l94">Line 94:</td> <td colspan="2" class="diff-lineno">Line 94:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Just what physically corresponds to that 'characteristic velocity' we call Isp is different in different propulsion systems -- but for performance purposes, it doesn't matter. Whether it be fuel in an airbreathing engine, propellant in a rocket, or reaction mass being expelled from some other energy supply onboard, if you're using something up to get your propulsion, Isp defines how much propulsion you get for each unit of consumed mass.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Just what physically corresponds to that 'characteristic velocity' we call Isp is different in different propulsion systems -- but for performance purposes, it doesn't matter. Whether it be fuel in an airbreathing engine, propellant in a rocket, or reaction mass being expelled from some other energy supply onboard, if you're using something up to get your propulsion, Isp defines how much propulsion you get for each unit of consumed mass.</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[Category:Spacecraft & Infrastructure‏‎]]</ins></div></td></tr> </table>

Lwcamp https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=822&oldid=prev ROCKETGUY at 18:16, 6 December 2021 2021-12-06T18:16:13Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 11:16, 6 December 2021</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l68">Line 68:</td> <td colspan="2" class="diff-lineno">Line 68:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Psp = acceleration * (Relevant Velocity)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Psp = acceleration * (Relevant Velocity)</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>This is '''not''' the most common way of talking about this concept; each type of propulsion system has its own vocabulary. However the parameter usually appears in some form or another -- rocket people talk about "thrust to weight" ratio, and nuclear-electric people talk about "alpha" which is the inverse of specific power (kg/W). <del style="font-weight: bold; text-decoration: none;">This </del>emerged in study on <del style="font-weight: bold; text-decoration: none;">how to compare dissimilar propulsion systems </del><ref>Millis, Marc G., Jeff Greason, and Rhonda Stevenson. Breakthrough Propulsion Study: Assessing Interstellar Flight Challenges and Prospects. No. HQ-E-DAA-TN60290. 2018. </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>This is '''not''' the most common way of talking about this concept; each type of propulsion system has its own vocabulary. However the parameter usually appears in some form or another -- rocket people talk about "thrust to weight" ratio, and nuclear-electric people talk about "alpha" which is the inverse of specific power (kg/W). <ins style="font-weight: bold; text-decoration: none;">The use of Psp as a way to compare dissimiliar propulsion systems </ins>emerged in <ins style="font-weight: bold; text-decoration: none;">a </ins>study on <ins style="font-weight: bold; text-decoration: none;">that subject.</ins><ref>Millis, Marc G., Jeff Greason, and Rhonda Stevenson. Breakthrough Propulsion Study: Assessing Interstellar Flight Challenges and Prospects. No. HQ-E-DAA-TN60290. 2018. </div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> retrieved from https://ntrs.nasa.gov/api/citations/20180006480/downloads/20180006480.pdf </ref> as a metric that could apply to all of them.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> retrieved from https://ntrs.nasa.gov/api/citations/20180006480/downloads/20180006480.pdf </ref> as a metric that could apply to all of them.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> </table>

ROCKETGUY https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=821&oldid=prev ROCKETGUY at 18:10, 6 December 2021 2021-12-06T18:10:35Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 11:10, 6 December 2021</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l24">Line 24:</td> <td colspan="2" class="diff-lineno">Line 24:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is (<math>10^{12}</math> m) / (<math>10^4</math> m/s), or <math>1 \cdot 10^8</math> seconds. (1 year is 3.<del style="font-weight: bold; text-decoration: none;">16E7 </del>seconds, or very close to pi<del style="font-weight: bold; text-decoration: none;">*1e7 </del>seconds), so the trip takes about 3.16 years (<del style="font-weight: bold; text-decoration: none;">1E8</del>/3.<del style="font-weight: bold; text-decoration: none;">16E7 </del>= 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is (<math>10^{12}</math> m) / (<math>10^4</math> m/s), or <math>1 \cdot 10^8</math> seconds. (1 year is <ins style="font-weight: bold; text-decoration: none;"><math></ins>3.<ins style="font-weight: bold; text-decoration: none;">16 \cdot 10^7</math> </ins>seconds, or very close to <ins style="font-weight: bold; text-decoration: none;"><math>\</ins>pi <ins style="font-weight: bold; text-decoration: none;">\cdot 10^7</math> </ins>seconds), so the trip takes about 3.16 years (<ins style="font-weight: bold; text-decoration: none;"><math>1 \cdot 10^8</math></ins>/<ins style="font-weight: bold; text-decoration: none;"><math></ins>3.<ins style="font-weight: bold; text-decoration: none;">16 \cdot 10^7</math> </ins>= 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td></tr> <tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l36">Line 36:</td> <td colspan="2" class="diff-lineno">Line 36:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>minimum_acceleration = (peak velocity)^2 / (voyage distance)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>minimum_acceleration = (peak velocity)^2 / (voyage distance)</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>And in this case, the trip takes just twice as long as it would for the same peak velocity but an instantaneous impulse. For the example given, that is an acceleration of 0.0001 m/s^2 (<del style="font-weight: bold; text-decoration: none;">1E</del>-4 m/s^2), and you get velocity and distance curves like this:</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>And in this case, the trip takes just twice as long as it would for the same peak velocity but an instantaneous impulse. For the example given, that is an acceleration of 0.0001 m/s^2 (<ins style="font-weight: bold; text-decoration: none;"><math>1 \cdot 10^{</ins>-4<ins style="font-weight: bold; text-decoration: none;">}</math> </ins>m/s^2), and you get velocity and distance curves like this:</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_brachistochrone.jpg]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_brachistochrone.jpg]]</div></td></tr> </table>

ROCKETGUY https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=820&oldid=prev ROCKETGUY at 18:07, 6 December 2021 2021-12-06T18:07:01Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 11:07, 6 December 2021</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l24">Line 24:</td> <td colspan="2" class="diff-lineno">Line 24:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is <math>10^{12}</math> m / <math>10^4</math> m/s, or <math>1 \cdot 10^8</math> seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is <ins style="font-weight: bold; text-decoration: none;">(</ins><math>10^{12}</math> m<ins style="font-weight: bold; text-decoration: none;">) </ins>/ <ins style="font-weight: bold; text-decoration: none;">(</ins><math>10^4</math> m/s<ins style="font-weight: bold; text-decoration: none;">)</ins>, or <math>1 \cdot 10^8</math> seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td></tr> </table>

ROCKETGUY https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=819&oldid=prev ROCKETGUY at 18:06, 6 December 2021 2021-12-06T18:06:04Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 11:06, 6 December 2021</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l9">Line 9:</td> <td colspan="2" class="diff-lineno">Line 9:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The simplest case is a trip which is out in space, far enough away from planets and stars that the effect of gravity can be ignored. Even inside a Solar system, this comes pretty close for very fast trips because gravity doesn’t have a lot of time to affect the course. When your cruise velocity is more than about 1.5 times the local escape velocity from the Sun, and the start and end point are on the same side of the Sun rather than crossing near the Sun during the trip, the straight-line approximation works fairly well.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The simplest case is a trip which is out in space, far enough away from planets and stars that the effect of gravity can be ignored. Even inside a Solar system, this comes pretty close for very fast trips because gravity doesn’t have a lot of time to affect the course. When your cruise velocity is more than about 1.5 times the local escape velocity from the Sun, and the start and end point are on the same side of the Sun rather than crossing near the Sun during the trip, the straight-line approximation works fairly well.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>We will work everything in metric units (SI), meters, kilograms, and seconds. One of the challenges in explaining propulsion is that it is easy to get tangled up in the units. That requires familiarity with [[scientific notation]], '((NOTE: do we want to typeset scientific notation or use computer notation, 1.2E23 and so on? Typesetting is a pain but more formal, we should probably make that style decision for use throughout))'. Distances in spaceflight are usually measured in kilometers (1000 meters), miles (1609 meters), nautical miles (1852 meters), astronomical units (AU) (<math>1.5 \cdot 10^11</math> meters), light years (ly) (<math>9.5 \cdot 10^15</math> meters), or parsecs (pc) (<math>3.1 \cdot 10^16</math> meters). Though not in common use, a useful metric unit for interstellar distances is the Petameter (Pm), <math>1 \cdot 10^15</math> neters; a light year is then 9.5 Pm.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>We will work everything in metric units (SI), meters, kilograms, and seconds. One of the challenges in explaining propulsion is that it is easy to get tangled up in the units. That requires familiarity with [[scientific notation]], '((NOTE: do we want to typeset scientific notation or use computer notation, 1.2E23 and so on? Typesetting is a pain but more formal, we should probably make that style decision for use throughout))'. Distances in spaceflight are usually measured in kilometers (1000 meters), miles (1609 meters), nautical miles (1852 meters), astronomical units (AU) (<math>1.5 \cdot 10^<ins style="font-weight: bold; text-decoration: none;">{</ins>11<ins style="font-weight: bold; text-decoration: none;">}</ins></math> meters), light years (ly) (<math>9.5 \cdot 10^<ins style="font-weight: bold; text-decoration: none;">{</ins>15<ins style="font-weight: bold; text-decoration: none;">}</ins></math> meters), or parsecs (pc) (<math>3.1 \cdot 10^<ins style="font-weight: bold; text-decoration: none;">{</ins>16<ins style="font-weight: bold; text-decoration: none;">}</ins></math> meters). Though not in common use, a useful metric unit for interstellar distances is the Petameter (Pm), <math>1 \cdot 10^<ins style="font-weight: bold; text-decoration: none;">{</ins>15<ins style="font-weight: bold; text-decoration: none;">}</ins></math> neters; a light year is then 9.5 Pm.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Consider a trip of about 6.6 AU … a little further than the closest distance from Earth to Jupiter, a little closer than Earth to Saturn. That’s <del style="font-weight: bold; text-decoration: none;">1E12 </del>meters. We’ll want to go there and come to a stop, rather than just passing.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Consider a trip of about 6.6 AU … a little further than the closest distance from Earth to Jupiter, a little closer than Earth to Saturn. That’s <ins style="font-weight: bold; text-decoration: none;"><math>1 \cdot 10^{12}</math> </ins>meters. We’ll want to go there and come to a stop, rather than just passing.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A few terms: velocity is the rate of change of distance (meters/second), and acceleration is the rate of change of velocity (meters/second^2).</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A few terms: velocity is the rate of change of distance (meters/second), and acceleration is the rate of change of velocity (meters/second^2).</div></td></tr> <tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l24">Line 24:</td> <td colspan="2" class="diff-lineno">Line 24:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is <math>10^12</math> m / <math>10^4</math> m/s, or <math>1 \cdot 10^8</math> seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is <math>10^<ins style="font-weight: bold; text-decoration: none;">{</ins>12<ins style="font-weight: bold; text-decoration: none;">}</ins></math> m / <math>10^4</math> m/s, or <math>1 \cdot 10^8</math> seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td></tr> </table>

ROCKETGUY https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=818&oldid=prev ROCKETGUY at 17:56, 6 December 2021 2021-12-06T17:56:59Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 10:56, 6 December 2021</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l24">Line 24:</td> <td colspan="2" class="diff-lineno">Line 24:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is <math><del style="font-weight: bold; text-decoration: none;">1 \cdot </del>10^12</math> m /<math><del style="font-weight: bold; text-decoration: none;">1 \cdot </del>10^4</math> m/s, or <math>1 \cdot 10^<del style="font-weight: bold; text-decoration: none;">18</del></math> seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is <math>10^12</math> m / <math>10^4</math> m/s, or <math>1 \cdot 10^<ins style="font-weight: bold; text-decoration: none;">8</ins></math> seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td></tr> </table>

ROCKETGUY https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=817&oldid=prev ROCKETGUY at 17:54, 6 December 2021 2021-12-06T17:54:29Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 10:54, 6 December 2021</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l24">Line 24:</td> <td colspan="2" class="diff-lineno">Line 24:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is <math>1 \cdot 10^12</math><del style="font-weight: bold; text-decoration: none;">1E12 </del>m /<math>1 \cdot 10^4</math> m/s, or <math>1 \cdot 10^18</math> seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<math>1 \cdot 10^4</math>) m/s, then the time is <math>1 \cdot 10^12</math> m /<math>1 \cdot 10^4</math> m/s, or <math>1 \cdot 10^18</math> seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td></tr> </table>

ROCKETGUY https://www.galacticlibrary.net/mediawiki-1.41.1/index.php?title=Propulsion_Performance&diff=816&oldid=prev ROCKETGUY at 17:54, 6 December 2021 2021-12-06T17:54:05Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 10:54, 6 December 2021</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l9">Line 9:</td> <td colspan="2" class="diff-lineno">Line 9:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The simplest case is a trip which is out in space, far enough away from planets and stars that the effect of gravity can be ignored. Even inside a Solar system, this comes pretty close for very fast trips because gravity doesn’t have a lot of time to affect the course. When your cruise velocity is more than about 1.5 times the local escape velocity from the Sun, and the start and end point are on the same side of the Sun rather than crossing near the Sun during the trip, the straight-line approximation works fairly well.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The simplest case is a trip which is out in space, far enough away from planets and stars that the effect of gravity can be ignored. Even inside a Solar system, this comes pretty close for very fast trips because gravity doesn’t have a lot of time to affect the course. When your cruise velocity is more than about 1.5 times the local escape velocity from the Sun, and the start and end point are on the same side of the Sun rather than crossing near the Sun during the trip, the straight-line approximation works fairly well.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>We will work everything in metric units (SI), meters, kilograms, and seconds. One of the challenges in explaining propulsion is that it is easy to get tangled up in the units. That requires familiarity with [[scientific notation]], '((NOTE: do we want to typeset scientific notation or use computer notation, 1.2E23 and so on? Typesetting is a pain but more formal, we should probably make that style decision for use throughout))'. Distances in spaceflight are usually measured in kilometers (1000 meters), miles (1609 meters), nautical miles (1852 meters), astronomical units (AU) (1.<del style="font-weight: bold; text-decoration: none;">5E11 </del>meters), light years (ly) (9.<del style="font-weight: bold; text-decoration: none;">5E15 </del>meters), or parsecs (pc) (3.<del style="font-weight: bold; text-decoration: none;">1E16 </del>meters). </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>We will work everything in metric units (SI), meters, kilograms, and seconds. One of the challenges in explaining propulsion is that it is easy to get tangled up in the units. That requires familiarity with [[scientific notation]], '((NOTE: do we want to typeset scientific notation or use computer notation, 1.2E23 and so on? Typesetting is a pain but more formal, we should probably make that style decision for use throughout))'. Distances in spaceflight are usually measured in kilometers (1000 meters), miles (1609 meters), nautical miles (1852 meters), astronomical units (AU) (<ins style="font-weight: bold; text-decoration: none;"><math></ins>1.<ins style="font-weight: bold; text-decoration: none;">5 \cdot 10^11</math> </ins>meters), light years (ly) (<ins style="font-weight: bold; text-decoration: none;"><math></ins>9.<ins style="font-weight: bold; text-decoration: none;">5 \cdot 10^15</math> </ins>meters), or parsecs (pc) (<ins style="font-weight: bold; text-decoration: none;"><math></ins>3.<ins style="font-weight: bold; text-decoration: none;">1 \cdot 10^16</math> </ins>meters)<ins style="font-weight: bold; text-decoration: none;">. Though not in common use, a useful metric unit for interstellar distances is the Petameter (Pm), <math>1 \cdot 10^15</math> neters; a light year is then 9.5 Pm</ins>.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Consider a trip of about 6.6 AU … a little further than the closest distance from Earth to Jupiter, a little closer than Earth to Saturn. That’s 1E12 meters. We’ll want to go there and come to a stop, rather than just passing.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Consider a trip of about 6.6 AU … a little further than the closest distance from Earth to Jupiter, a little closer than Earth to Saturn. That’s 1E12 meters. We’ll want to go there and come to a stop, rather than just passing.</div></td></tr> <tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l24">Line 24:</td> <td colspan="2" class="diff-lineno">Line 24:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>t = d/v</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<del style="font-weight: bold; text-decoration: none;">1E4</del>) m/s, then the time is <del style="font-weight: bold; text-decoration: none;">1E12m </del>/<del style="font-weight: bold; text-decoration: none;">1E4 </del>m/s, or <del style="font-weight: bold; text-decoration: none;">1E8 </del>seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>If the coast velocity is 10000 (<ins style="font-weight: bold; text-decoration: none;"><math>1 \cdot 10^4</math></ins>) m/s, then the time is <ins style="font-weight: bold; text-decoration: none;"><math>1 \cdot 10^12<</ins>/<ins style="font-weight: bold; text-decoration: none;">math>1E12 m /<math>1 \cdot 10^4</math> </ins>m/s, or <ins style="font-weight: bold; text-decoration: none;"><math>1 \cdot 10^18</math> </ins>seconds. (1 year is 3.16E7 seconds, or very close to pi*1e7 seconds), so the trip takes about 3.16 years (1E8/3.16E7 = 3.16). The graphs below are for 0.01 m/s^2 acceleration on that voyage during both acceleration and braking, which, over that distance, is very nearly an instant jump to cruise velocity. Missions where you can neglect the distance and time spent accelerating and decelerating are called 'instantaneous impulse' trajectories.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:V_vs_t_highaccel.jpg]]</div></td></tr> </table>

ROCKETGUY