<div class="quoteheader"><div class="topslice_quote"><a href="https://elliquiy.com/forums/index.php?topic=148593.msg7046254#msg7046254">Quote from: mia h on 10-10-2012, 00:34:31</a></div></div><blockquote class="bbc_standard_quote">Might not be a deliberate error, but your calculation is still out.<br/><br/>If it takes 7kg of fuel to carry to lift 10kg of cargo, you don't have to worry about lifting all of the fuel into orbit as you use it up as you go, so half way up you've only got 3.5kg of fuel to carry :P<br/></blockquote><div class="quotefooter"><div class="botslice_quote"></div></div><br/>Actually, no,<br/><br/>If it takes 7kg of fuel to lift 10kg, then half way up you have probably got about 7Kg, because you don't burn the extra fuel until you run out of the normal fuel load! The engines burn the fuel at the same rate regardless, but due to the extra mass there is more inertia and thus the same force applied produces less acceleration. Thus the engines need to burn longer to achieve escape velocity, thus requiring more fuel.<br/><br/>However, the maths is totally beyond me, so I oversimplified for the purpose of the RP.<br/><br/>And Blinkin, you are missing one important fact... I did the calculation<em>backwards</em>! I started with the amount of fuel required to get the ship into orbit (an arbitrary figure), not the thrust of the engines or anything. I then invented an arbitrary value fior the overall mass of the shuttle and crew, divided one by the other and came up with a value required in fuel to get each kg of the shuttle into orbit.<br/><br/>That value cannot be divided by half, nor by anything else, to give a value required to get the shuttle half way into orbit. To obtain that value would require the use of integral calculus, which I don't feel like doing. In fact I'm not even sure I could.<br/><br/>The Saturn V rockets used in the Moon landings had bigger engines in the lower stages which burned the fuel faster and thus produced more thrust. This shuttle has one set of engines. Now, I'm not saying that they couldn't be throttled back to save fuel, but doing so wouldn't actually save fuel because the reduction in thrust would simply reduce the acceleration which would increase the time taken to reach escape velocity which would increase the amount of fuel required....<br/><br/>The other difference is that this shuttle takes off from a runway, rather than vertically, and thus the acceleration needs to build more slowly.<br/><br/>However, both of those facts are irrelevant, as the simplification hangs on the fact that "The shuttle takes this much fuel to reach orbit". That fact takes into account the fact that less fuel is required as the shuttle gets lighter.<br/><br/>Sorry and all that. Please don't make me regret posting what I did?