From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.0 required=5.0 tests=BAYES_40 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,1dd28d5040ded1f8 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-05-25 15:07:52 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!bloom-beacon.mit.edu!nycmny1-snh1.gtei.net!news.gtei.net!news-out.visi.com!hermes.visi.com!nnxp1.twtelecom.net!news-east.rr.com!chnws02.ne.ipsvc.net!cyclone.ne.ipsvc.net!24.128.8.70!typhoon.ne.ipsvc.net.POSTED!not-for-mail Message-ID: <3CF00B8C.907@attbi.com> From: "Robert I. Eachus" Organization: Eachus Associates User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:0.9.4.1) Gecko/20020314 Netscape6/6.2.2 X-Accept-Language: en,pdf MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Announce: Grace project site operational References: <3CD88FBD.4070706@telepath.com> <3CD91E31.1060004@telepath.com> <3CD94E63.3050607@mail.com> <4519e058.0205081400.58283a90@posting.google.com> <3CDA85F3.A3F7D318@despammed.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Date: Sat, 25 May 2002 22:03:40 GMT NNTP-Posting-Host: 24.61.239.24 X-Complaints-To: abuse@attbi.com X-Trace: typhoon.ne.ipsvc.net 1022364220 24.61.239.24 (Sat, 25 May 2002 18:03:40 EDT) NNTP-Posting-Date: Sat, 25 May 2002 18:03:40 EDT Xref: archiver1.google.com comp.lang.ada:24800 Date: 2002-05-25T22:03:40+00:00 List-Id: Wes Groleau wrote: > I didn't believe it when I read how he took > "one -10" (a drop in temperature of ten degrees) > and turned it into "the other -10" (ten degrees > below freezing). The worst case resulted in the Apollo fire that killed three astronauts. Two tests were combined. One that required operation in 3 psi oxygen, and another that required pressurization of the command module to 3 psi (above the surrounding pressure) for leak testing. The medical doctor who signed off on the combined test did so because all of the medical documentation read 3 psi oxygen, which is about the partial pressure of oxygen in the atmosphere. Forget for a moment that pressurizing the capsule with 18 psi oxygen made it a bomb, ask your doctor what would happen to your lungs on 18 psi oxygen, 0% CO2, 0% H2O, 0% N2, for that matter 0% anything else. In scuba diving, the partial pressure of O2 can get that high in "technical" diving (below 150 feet), but the usual for technical diving is to use a helium/oxygen mix, and keep the oxygen partial pressure to reasonable levels. "Oxygen tents" in hospitals seldom go above 7 or 8 psi oxygen partial pressure, in other words a 50/50 mix of oxygen and air. Mountain climbers use pure oxygen above around 20,000 feet, but again the absolute O2 pressure is below 3 or 4 psi. One of the changes made subsequent to the Apollo fire was to a 50/50 He/O2 mix. This allowed the command capsule to be filled with the mix at atmospheric pressure before launch, then reduce to 5 psi (2.5 psi O2 pp) on orbit. Incidently I always thought that the most frightening part of the early spacecraft flights was taking off in a container with a hole in it to let the air out and hoping that the hole would close properly. Once the rockets stopped firing you could do something about it, but you would probably be out of oxygen by then. This is one of the things the Space Shuttle fixed--no venting required during the boost phase. Along with a max-Q where you could do something other than holding on until the shaking stopped. Yes, the astronauts are strapped in, but I mean it literally. In Mercury, Gemini, and Apollo, if you didn't hold on to keep your hands from uncontrollably banging around at max-Q, you could damage your hands--and the spacecraft. Add the pogo effect, see Apollo 6, and you were just glad to survive the ride. (The pogo effect resulted from resonances between the Saturn I structure and the pipes bringing fuel to the engines. This resulted in the momentary g-forces banging back and forth between 0 and 10 gs or so. On Apollo 6 it was so bad that parts of the lunar module adapter, which contained the LM and connected the command/service module to the Saturn booster fell off. The cure was to fill parts of the Saturn with helium before launch to change the resonant frequencies.)