Date: Tue, 11 Aug 92 05:14:14 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #097 To: Space Digest Readers Precedence: bulk Space Digest Tue, 11 Aug 92 Volume 15 : Issue 097 Today's Topics: Effective Temperatures Home made rockets (2 msgs) Navier Stokes Equations Optus I-B/Long March launch scheduled 2300Z 13 Aug SPS Star Trek (anti-)realism (2 msgs) Tethers Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 11 Aug 92 06:15:51 GMT From: Richard Pulley Subject: Effective Temperatures Newsgroups: sci.space I am trying to write a computer program which acts as a combined star atlas & database. I am using a database with information about each star's B-V value and spectral class (e.g II A4). I have the following table for computing effective temperatures for a star: static float EffT[SIZES][SPECS] = { // spec B0 B5 A0 A5 F0 F5 G0 G5 K0 K5 M0 M5 M9 Sizes {22000,14200,9000,8000,6900,6100,5400,4700,4000,3300,2800,2000,1900}, //Ia {24000,14500,9100,8100,7000,6300,5600,4850,4100,3500,2900,2200,2000}, //Ib {25000,15100,9300,8200,7100,6400,5700,5000,4300,3650,3100,2400,2100}, //II {26000,15200,9500,8300,7200,6500,5800,5100,4500,3800,3400,2650,2200}, //III {27000,15400,9700,8400,7300,6600,5900,5200,4700,3950,3450,2725,2250}, //IV {28000,15500,9900,8500,7400,6700,6000,5500,4900,4100,3500,2800,2300}, //V {29000,15600,10100,8600,7500,6800,6100,5600,5000,4200,3600,2900,2400} //VI }; Does anyone have similar information on type O stars, and white dwarfs? Is there a simple formula for this table?? -- Richard =====================| richardp@otc.otca.oz.au |===================== : ___________________________ ;__. : : (612) |\ /| _/ | |\ : | \ / | _/ \__| \. _____:___________ | \___________________/ | / \ / ___________ \ | Richard Pulley | ,! \ \_ / \ _/ | OTC R & D | \ ! . ! 287-3182 ! | 231 Elizabeth St, | \ ___^. +=======/ \___________/ | Sydney 2001 | \__/ \__/ (02) |_________________________| .. 0 ========================================================================= ------------------------------ Date: 11 Aug 1992 04:44:02 GMT From: "David M.V. Utidjian" Subject: Home made rockets Newsgroups: sci.space This sort of discussion turns up on rec.pyrotechnics occasionally..... o You can try and discourage people from experimenting with homemade fuels. It will only work for a few of them. o You can tell them what to definitely NOT try. (Potassium Chlorate) The pros NEVER use Potassium Chlorate... for safety reasons. o There are allways going to be some that are going to try it some of them are a bit dumb, some a bit careless, all are extremely lucky... no amount of statistics or commomn sense will stop them. o Back in the fifties and early sixties they tried to form clubs for this kind of thing. They recognized that kids would try to build them anyway. Then came Estes, and they said buy em'. o There are currently available reloadable engines up to, I think, 20,480 Newton-seconds Specific Impulse! and as small as 20 N-s. Why bother with anything else... these reloadables are much more efficient than anything an individual is likely to make, and MUCH cheaper. o Right now us people in HPR (High Powered Rocketry) are having the DOT review the rules for transport of reloadables. We DO NOT need any negative publicity at the moment, or in the future. The original poster is just **** out of luck. I do not remember where he is located. There are quite a few people in the US, Australia, New Zealand and the UK that are into amateur rocketry. These groups have been around for a while. Check rec.models.rockets and rec.pyrotechnics if you want to get in touch with them. David Utidjian ------------------------------ Date: Tue, 11 Aug 1992 06:27:40 GMT From: Scott Fisher Subject: Home made rockets Newsgroups: sci.space roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >Potassium or sodium chlorate was what the little brother of a friend of a >friend tried as an oxidizer. It detonated while he was assembling it, and >punched so many holes through his intestine that he died horribly of >infection within a few days. Whichever one he used, I think it has a >pretty poor reputation for stability in amateur use. When I was a "little kid" 14 :-) A friend and I were making rocket fuel out of sulphur and pool chlorine (if I remember correctly). Anyhow on packing the rocket POOOOM! I was knocked off my feet and my friend spent 2 weeks in hospital with severe chemical burns to his cornea and face and mechanical injury to his stomach. I remember him standing there with his clothes hanging off him (just like in the cartoons) with his hair frazzled. He survived. I survived. Just :-) Moral...I leave anything like that to the proffesionals now. Lucky the accident didn't happen with the "real" explosives we were playing with earlier that day. (We were blowing up an old farm truck with fertilizer and diesel mix left over from dam making). Regards Scott. _______________________________________________________________________________ Scott Fisher [scott@psy.uwa.oz.au] PH: Aus [61] Perth (09) Local (380 3272). _--_|\ N Department of Psychology / \ W + E University of Western Australia. Perth --> *_.--._/ S Nedlands, 6009. PERTH, W.A. v *** ERROR 144 - REBOOT? is a registered trademark of ENSONIQ Corp *** ------------------------------------------------------------------------------- ------------------------------ Date: Tue, 11 Aug 92 02:56:57 GMT From: Ronald Fedkiw Subject: Navier Stokes Equations Newsgroups: sci.space If anyone knows of a good reference to find either of the following, please let me know... (1) Axisymmetric Compressible Navier Stokes Equations (the incompressible isn't much help) (2) Need some sort of approximation for the size and structure of the boundry layer created when solving (1) or even the 2-D compressible Navier Stokes equations for flow past a blunt body Thanks, Ron -- Ron Fedkiw (rfedkiw@redwood.math.ucla.edu) A plan is made by someone who is sitting and thinking ... while others are doing. ------------------------------ Date: 11 Aug 92 07:30:44 GMT From: "Gregory N. Bond" Subject: Optus I-B/Long March launch scheduled 2300Z 13 Aug Newsgroups: sci.space Launch of the Optus I-B satellite is scheduled for 0900 AEST (+1000) August 14 (2300Z August 13) according to reports in todays papers. The launch will be from Xichang, China on a Long March booster. This will be the second attempted launch, an earlier try on March 22 was aborted just after main engine ignition due to some unspecified problems (from memory, low chamber pressure on one of the strap-ons). Luckily, there was no major fire and the payload was unharmed. Optus I-B is a Hughes-built bird, known until recently as Aussat I-B. It is the first of two new-generation satellites providing direct-broadcast TV and carrier services to Australia. (Actually, the whole thing is a complete WOMBAT(*) and is the booby prize for Optus gaining the licence as the second Australian phone carrier). Greg. ((*) WOMBAT, a large but nearly-blind burrowing mammal of legendary stupidity native to Australia. Also SLA: Waste Of Money, Brains And Time.) -- Gregory Bond Burdett Buckeridge & Young Ltd Melbourne Australia ``USL has never sold long distance. You're going after the wrong men in black hats. (Or, in the case of Plan 9, black space suits)'' - Tom Limoncelli ------------------------------ Date: 11 Aug 92 03:55:35 GMT From: "Frederick A. Ringwald" Subject: SPS Newsgroups: sci.space In article <9208101330.AA01472@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: > -Again, kindly supply numbers and literature references. Otherwise, how > -can I tell if your arguments aren't just anecdotal? > > If they had good solid numbers and the technology all figured out, they'd > probably have built it by now, or completely abandoned the idea. Well...look, for example, at nuclear fission... > According to Steve Willner, if you choose 10.6um (handy because that's what > a CO2 laser put out), then the main absorption is by water vapor, at about > 1% per millimeter equivalent. So it wouldn't heat the upper atmosphere Ah, now this is interesting, and something I hadn't heard before. There is indeed an atmospheric window at 10-12 microns, to let in such a beam; and an invisible beam which doesn't interfere with telecommunications and isn't renowned for its cooking ability will be a lot easier to sell to the public. Can you get me a literature reference? Heating the upper atmosphere (as low as 10,000 feet) may not be much of a problem, as it is quite dry and nearly 100% transparent to this wavelength (cf. Zombeck, M. 1990, Handbook of Space Astronomy & Astrophysics, Ch. 4). We've been doing astronomy at these wavelengths for years: the chief problems are absorption from water vapor (making a need for a high, dry site, such as Hawaii) and thermal background (*not* a problem for a gigawatt laser). The lower atmosphere might, however, run up problems with losses. If you locate the receiver on a high mountain, watch out you don't melt all the snow: it wouldn't look good. Then again, large, tethered balloons might work as power receivers, and obviate a lot of trouble (although incur some transmission loss, but this doesn't seem too bad from 7-10 extra miles of cable). The balloons could be located anywhere the neighbors would allow them, or even offshore. It's beginning to sound convincing, but there *is* this MAJOR issue of cost. What's being done *now* to bring down the cost of space flight and operations? ------------------------------ Date: 11 Aug 92 00:48:23 GMT From: Kenneth Ng Subject: Star Trek (anti-)realism Newsgroups: sci.space In article <1992Aug6.183507.19041@dartvax.dartmouth.edu:, Frederick.A.Ringwald@dartmouth.edu (Frederick A. Ringwald) writes: : In article <1992Aug6.150955.15156@rsd0.rsd.dl.nec.com> : buzz@rsd.dl.nec.com (Buzz McDermott) writes: : > Personally, I like the fact that it took them about 10 minutes to accelerate : > from earth to Sun (for their spring-board acceleration for time travel) : > despite the fact that they were, at one point, going 'warp 8' and then 'off : > the dial'. Isn't 'warp 8' supposed to be equivalent to something like 256 : > times the speed of light? Gosh, the Sun must be further from earth than I : > thought..... : By the way, to have stars streaming by you, you'd have to be going : several parsecs per second - and at that kind of speed, you could cross : the Milky Way in eight hours (work it out yourself). Hmmm, I guess when : they say "real space travel wouldn't look like that, it's just an easy : video effect," they're right! My favorite in science fiction space travel like Star Trek and Star Wars is the asteroid field. Never mind that even crowded fields they are still (in reality) mostly space. -- Kenneth Ng Please reply to kdn5669@hertz.njit.edu for now. Apple and AT&T lawsuits: Just say NO! ------------------------------ Date: 11 Aug 92 06:25:32 GMT From: Scott Stanford Subject: Star Trek (anti-)realism Newsgroups: sci.space In article <1992Aug6.110321.28381@dartvax.dartmouth.edu> Frederick.A.Ringwald@dartmouth.edu (Frederick A. Ringwald) writes: > >2) No real navy would let a 35-year-old command a capital ship, no >matter how good he was (unless there had just been heavy losses in a >war, in which case exploration would not be a high priority). No real navy would let families on its ships, either, such as in the pilot New Generation episode, especially into dangerous regions (where the Big E always seems to be). Scott ------------------------------ Date: Mon, 10 Aug 92 22:00:43 PDT From: Eric_S_Klien@cup.portal.com Subject: Tethers Newsgroups: sci.space Would it be possible to put something in near orbit over Nevada and attach tethers to it so that people could reach the object via elevators? I know it wouldn't be easy, but is there a way to pull this off? Eric Klien ------------------------------ End of Space Digest Volume 15 : Issue 097 ------------------------------