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*To*: KellySt@aol.com, kgstar@most.magec.com, stevev@efn.org, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, David@InterWorld.com, lparker@destin.gulfnet.com, bmansur@oc.edu*Subject*: Re: New idea Laser launcher/scoop systems*From*: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)*Date*: Fri, 08 Mar 1996 16:32:22 +0100

Reply to Kelly and Steve, worring about ratios >Actually, now that I think about it there is a dangerous likely flaw in >this fuel launcher idea. > >Remember a while back when I ran the numbers on fuel-to-payload ratios >for different fuel types? Remember that hydrogen came out at _minimum_ >to need 1,000,000 units of hydrogen to one unit of payload to reach even >low relativistic speeds. It's a long time ago already, so I dug up you formula: / 2 \ ArcTanh[v]/a | r Sqrt[1 - a ] | f = | ---------------- | \ r + a / f = fraction of mass that can be payload r = reaction mass velocity (in lightspeed) v = final spacecraft velocity (in lightspeed) a = acceleration (in lightspeed --> 10 becomes 10/c) Using a small r (0.081c) gives ratios of about f=1/45 which seems reasonable compared to your 1:1,000,000. All this is for v=0.3c For v=0.2 this ratio is down to 1:12, and for v=0.4 it is 1:180 With my own formulas I come to the same conclusion, some time ago I tried to convince Kelly that with a 1:16 ratio we could come quite far. Tim

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