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*To*: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)*Subject*: Re: more physics (short)*From*: kgstar@most.fw.hac.com (Kelly Starks x7066 MS 10-39)*Date*: Mon, 3 Jun 1996 08:07:55 -0500*Cc*: KellySt@aol.com, kgstar@most.fw.hac.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, DotarSojat@aol.com, neill@foda.math.usu.edu, 101765.2200@compuserve.com, MLEN3097@Mercury.GC.PeachNet.EDU

At 6:37 PM 6/2/96, Timothy van der Linden wrote: >>I went over the Bussard paper and found 14E6 as the upper exaust vel for p >>+ 11B. Which obviously isn't what I'm getting. Eiather I miscalculated >>the watts per Kg (I sent my equations for that in another letter) or I >>misread Bussards paper. (I suppose I could write him.) I'ld hate to write >>off about 15% of spec impulse if I didn't need to. (See table below.) > >>If you know how to get the exaust speed from Mev numbers let me know. I'm >>sure those numbers from the papers are correct. > >Watch carefully: > >The reaction as found in my tables book: > >H + 11B --> 3 4He + 8.7 MeV > >Let's assume energy conversion is 100% and ALL reaction products will be >accelerated in the 100% effective lineac. > >First turn MeV in to Joules: > >8.7 MeV = 8.7E6 * 1.602E-19 = 1.394E-12 Joule > >Then determine the weight of the particles in kg: > >H + 11B is approx 12 u (u=atomic mass unit) > >12 u = 12 * 1.661E-27 = 1.993E-26 Kg > >Thus the energy per kg is: > >1.394E-12 / 1.993E-26 = 6.995E13 J/Kg So we used the same numbers (thou in a different order) and got about the same number. One suprize, I had that the mass of Protons and neutrons as about 1.673 E-27 kg, where you have 1.661E-27. Is that a typo? We came up with the same velocity, which seems odd if we were using a different constant. Eiather way (unless Rex has an alternate opinion) it looks like the lower numbers I just computed are the ones to use. <Sigh> > >(Don't use much more significant numbers, if you do use them you need to >define some things more accurate and cannot simply think that 11 H weighs as >much as 11B.) > >Using E=0.5 m v^2 I still get v=11.8E6 m/s, so I really wonder how Bussard >can get a higher velocity, unless he dumps some of the reaction mass instead >of accelerating it. No the numbers were not based on an engineering output. That was supposed to be the direct output from the reactions. Could be I misread something and the 14E6 number was for something else (though I can't see what). >>I was working up the following table of the fuel mass ratios needed to get >>to or from certain speeds given the exaust velocities. >> >>NEW numbers >> >>Fuel --> Exhaust >>Vexh 75E6m/s 100 E6m/s 125 E6m/s 150 E6m/s >> >>p + 11B --> 3 4He >> 11,800,000 m/s 576.0 4,790.0 39,900 332,000 >> >>6Li + 6Li --> 3 4He >> (Combined) >> 17,800,000 m/s 67.6 275.0 1,120 4,570 >> >>3He + 3He --> 4He + 2 p >> 20,300,000 M/s 42.5 138.0 472 1,620 >> >>De + 3He --> 4He + p >> 26,500,000 m/s 16.9 43.5 112 287 > >Of course ;) I get completly different numbers (at least for higher Vend) > > 674 2,680 82,000 1,200,000 > 73 181 1,728 10,000 > 44 97 708 3,377 > 18 34 154 509 > >I assume this time relativistics is the origin (for 0.5c gamma=1.15 which >means its not almost equal to 1 anymore) for our differences ?? Why are you geting larger (often much larger) numbers for 75E6m/s, 125 E6m/s, and 150 E6m/s, but smaller for 100 E6m/s? Also the deltas don't seem even. Hum. I suppose I should rerun my numbers with relativistic equations. With our luck I'll come up with a third set of numbers. Your probably right about my non-relativistic numbers geting soft a .5c thou. I normally wouldn't have pushed them that far. But De + 3He was looking suprizingly good. >>Amazing how touchy the fuel ratios are to changes in exaust vel/specific >>impulse. Look at the difference between 6Li + 6Li and 3He + 3He! ;) > >Well yes, that is because of the energy per kilogram of fuel. Which is 3 >times higher for 3He + 3He. (This is what my "magic" number f says) > > >Timothy Pity you gave no way to use you magic number. (Like the value for given fuels?) Also the F number table didn't give the numbers for the fuels, which naturally didn't have even F numbers. Kelly ---------------------------------------------------------------------- Kelly Starks Internet: kgstar@most.fw.hac.com Sr. Systems Engineer Magnavox Electronic Systems Company (Magnavox URL: http://www.fw.hac.com/external.html) ----------------------------------------------------------------------

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