Path: utzoo!utgpu!cunews!mitel!testeng1!stanfiel From: stanfiel@testeng1.misemi (Chris Stanfield) Newsgroups: sci.space.shuttle Subject: Re: Lost Apollo 12? Message-ID: <4457@testeng1.misemi> Date: 17 Sep 90 19:45:50 GMT References: <36975@ut-emx> <6331@castle.ed.ac.uk> <1990Sep14.170238.1944@zoo.toronto.edu> Reply-To: stanfiel@testeng1.UUCP () Organization: Mitel CAE Services Lines: 29 In article <1990Sep14.170238.1944@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <6331@castle.ed.ac.uk> tjc@castle.ed.ac.uk (A J Cunningham) writes: >> I'm curious to know why an aircraft can take a lightning strike >>with no damage due to the Faraday Cage effect and Apollo 12 nearly had >>to be aborted. Is this where the trail of ionised gas is significant? > >Faraday cages are not magic; having a zillion amps flowing along the >outside of your vehicle can wreak havoc on internal electronics even >if it doesn't get inside. Aircraft don't always survive lightning >strikes. To add to this problem, almost all of an aircraft's cabling runs just under the aircraft's skin, so it is exposed to all of the eddy currents induced in the aircraft skin by the lightning strike. NASA (I think) has been flying a couple of experimental aircraft (sorry - can't remember the type) to observe lightning strike effects. The mods include removing all of the paint and taking extra care to ensure that the aircraft skin is electrically contiguous at all seams, etc. The latter is not the normal case, although all components *are* bonded together electrically. NASA then get the test pilots to fly these aircraft through lightning storms and observe and record the effects on the aircraft and its systems - must be a fun job! Actually, it may have been that the prime job of the flights was to observe lightning, but I can't remember now, and I can't find the article. I will try and look again, if anyone is interested. Chris Stanfield, Mitel Corporation: E-mail to:- uunet!mitel!testeng1!stanfiel (613) 592 2122 Ext.4960 We do not inherit the world from our parents - we borrow it from our children.