Payload to LEO?

[captainkoloth]

For weeks this has been driving me nuts: where can I go to calculate the performance of a launch vehicle? People always say, "Well, this launcher will give you 30 tons to LEO, change the engine to an RS-68 and you;'ll get 32 tons..." How can I calculate this? Is there a program I can get hold of?

 

[MeteorWayne]

Welcome to SDC!<br />No there's really no one place, AFAIK. Dozens of threads have addressed this issue here in Missions and Launches. But it's been pretty much launcher by launcher.<br />Perhaps spacester will pop in and tell us what sources he uses for his calculations <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>

 

[gunsandrockets]

This Delta-V calculator can help<br /><br />http://www.strout.net/info/science/delta-v/intro.html?varA=33&varB=25&varC=3.5&vexOrIsp=&varResult=1.18

 

[spacester]

Hey I appreciate the mention, but two things.<br /><br />First, it's best to just rely on a chart, the variables are just too many to summarize in a post. Someone here finally posted a good chart of payloads to LEO. Hopefully they'll show up.<br /><br />Secondly, I have declared a moratorium on my further significant contributions on these boards until at least somebody stands with me against the two so-called gentlemen here who continue to prevent rational and honest discourse. <br /><br />I can't take it any more, screw it.<br /><br />stevehw33 can eat my shorts. <br /><br />If you folks would rather have his contributions than mine, you can have him.<br /><br />ATM, I am referring to this thread:<br /><br />http://uplink.space.com/showthreaded.php?Cat=&Board=humanbio&Number=611138&page=0&view=collapsed&sb=5&o=0&vc=1<br /><br />As much as I am addicted to this place, I'm no longer interested in making any real effort to contribute at a place where that crap goes entirely unchecked. This is an old familiar pattern with this guy and if no one but me is willing to stand up to his crap, you guys can have him, and if you want answers to these questions, then you can just come over to my place to get them.<br /><br /><img src="/images/icons/tongue.gif" /><br /><br /><img src="/images/icons/mad.gif" /><br /><br />The mid term election is over, so this place no longer serves my purposes if I can't even talk about a subject such as spin-gravity without going it alone against that pitiful waste of intellect. <img src="/images/icons/mad.gif" /> <img src="/images/icons/mad.gif" /><br /><br />I've posted links on this subject for years and years and years here and not one of you people can stand with me? Screw it. I'm going to post this before I lose it entirely. Back tomorrow. <div class="Discussion_UserSignature"> </div>

 

[scottb50]

I for one comprehend what you have been saying and agree 100%. I suppose some people see these types of boards as only being good for argument, whether or not they have any idea what they are arguing about they seem to go to extremes just to get a rise out of someone.<br /><br />I appreciate someone pointing out errors and offering corrections when they know the facts because the basic idea may be valid but there is a better, or another, approach to the same solution. There is a big difference between constructive critisism and argument for the sake of argument.<br /><br />The thread you reference is a good example. Most of the 20 problems are more theory than fact to begin with and the only way to quantify them is to test them. <div class="Discussion_UserSignature"> </div>

 

[rfoshaug]

Spacester,<br /><br />At your link there's an image of an owl. Nice image, but no links, no info, nothing space related.<br /><br />I also think it's unfair of you to hijack this post to vent your frustration.<br /><br />As for the question by the original poster, I'd also like to see how these calculations are made.<br /><br /><img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>

 

[j05h]

Spacester- you've got to learn to ignore him or filter out his flames. Every forum has someone like Steve, sometimes they grow up, sometimes they remain flamers. There is a place for hard criticism here, but he does often cross that line into outright provocation. He doesn't hang out as much in Missions & Launches or the Biz/Tech board. <br /><br />To the original poster: If you are up to learning the math (I read it and wasn't, but learned a lot), please consider getting "Rocket Propulsion Elements" by Sutton. It covers all types of rockets from a theoretical/numbers standpoint.<br /><br />josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[spacester]

Thank you for the support, Scott. I'd better just leave it at that.<br /><br />rfoshaug, I am not trying to hijack the thread. Am I not allowed any slack in recompense for the hours I've spent here over the years providing answers to questions like this? Nuthin? Fine then.<br /><br />What browser are you using? I've verified the code for all modern browsers, checked it on mobile, checked it in a text reader. And all you see is a single image? No text at all? The link is to be found with the text 'llovingo's Rummy Mash'<br /><br />No, there is no space related stuff there yet. Am I breaking the rules or something? I thought I would host a fellow member's file as requested, I suppose that makes me a bad person somehow? This place blows my mind these days.<br /><br />To see the calcs, you can hope someone else here will start doing it or you can wait til I get my site up in January. I'm just about done with this one-way relationship.<br /> <div class="Discussion_UserSignature"> </div>

 

[spacester]

JO5H, I could learn to ignore him if I didn't feel like I'm the only one willing to stand up to his BS. He does stay away from M&L and B&T and IMO it's because he knows I'll be all over him if he screws around in my two favorites. But why should I not be allowed to participate in the other forums? On a subject dear to my heart where he spews garbage information? Why am I all alone in this? grrrrrrrrrrrrrrrrrrrrrr Is there no one else here interested in preserving actual intellectual integrity as opposed to the mere appearance of such? grrrrrrrrrrrrrrr<br /><br />The mods here sure as heck are no help in these things.<br />*<br />And with that, other than further replies, I won't further sully this fine thread.<br /><br />I'm going to give it another 24 hrs to try to chill out. The more I write the angrier I get. <div class="Discussion_UserSignature"> </div>

 

[rocketman5000]

firefox jumbles your page. It loaded fine with IE however when I copied and pasted the text

 

[bitbanger]

"What browser are you using? I've verified the code for all modern browsers, checked it on mobile, checked it in a text reader. And all you see is a single image? No text at all? The link is to be found with the text 'llovingo's Rummy Mash'"<br /><br />I'm using Firefox 2.0 and the CSS positioning is all messed up. The text boxes are overlapping and all pushed up to the top of the page.<br />

 

[spacester]

Thanks! I was told that it was good to go on Firefox. Obviously I need to install the browser myself and get my page fixed. Thank you very much for the feedback, looks like the sneak preview idea turned out to be useful after all.<br /><br />I'm calm today <img src="/images/icons/wink.gif" /> <br /><br />edit: I fixed it, FF doesn't support 'display: inline' which is what I was demo-ing in that top section . . . please try again . . . <div class="Discussion_UserSignature"> </div>

 

[edkyle98]

Try searching for "rocket equation", which will sites like the following.<br /><br />http://exploration.grc.nasa.gov/education/rocket/index.html<br />http://exploration.grc.nasa.gov/education/rocket/rktpow.html<br />http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node96.html<br /><br />You need enough information about a given launch vehicle to be able to use the rocket equation, which is:<br /><br />Delta-V (meters/sec) = 9.805 * ISP * ln(Mass Initial/Mass Final)<br /><br />where ISP is the average specific impulse in seconds of the rocket engine and "ln(Mass Initial/Mass Final)" is the natural logarithm of the mass ratio. The mass ratio is the ratio of the mass of a fully loaded stage to the mass of the stage at burnout. Note that the burnout mass is not equal to the dry mass for a liquid fueled stage. Burnout mass usually includes up to 1% residual propellants, which can have a substantial effect on the calculation. <br /><br />For a staged rocket, you have to run the equation for each stage of flight, taking the total mass of all of the stages and payload mass involved into account during each step, and then add up the total delta-v. <br /><br />To reach low earth orbit from Cape Canaveral, a launch vehicle needs to produce about 9,200-9,300 m/s of ideal delta-v. The precise number is uncertain because each launch vehicle has different gravity and drag losses (usually 1,500 - 2,000 m/s) that must be overcome. The LEO altitude also matters. <br /><br />From Kourou, the required delta-v would be about 60 m/s less than the Cape, due to the faster rotation of the Earth's surface at that lower latitude. From Baikonur, it would be about 115 m/s more than the Cape, since Baikonur is at a high