Date: Thu, 22 Jun 2000 08:08:06 +0200 From: Olaf Hoyer <ohoyer@fbwi.fh-wilhelmshaven.de> To: Brian Handy <handy@isass0.solar.isas.ac.jp> Cc: freebsd-hardware@FreeBSD.ORG Subject: Re: Hardware in space? Message-ID: <4.1.20000622075529.00979b80@mail.rz.fh-wilhelmshaven.de> In-Reply-To: <Pine.OSF.4.05.10006220859440.4383-100000@isass0.solar.isas .ac.jp> References: <4.1.20000621233928.026e05c0@mail.rz.fh-wilhelmshaven.de>
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-- While getting too cold probably isn't an issue, COOLING certainly is. >As a few people have alluded to, cooling in space becomes an issue because >there's no air. This will be a problem much earlier, because we'll >evacuate the payload several hours before launch. If there's a delay, the >package could wind up sitting on the launch rail for a few days under >vacuum. I've worried about blowing the top off the CPU from the heat. I >imagine it'll probably have to be heat-sunk to the chassis in some manner. >Someone mentioned using a 486; that's not such a bad idea. Mostly I'm >just grabbing data from the RS-232 ports and stuffing it to disk, so I'll >probably wind up doing some experimentation to see just what I'll need. > Hi! Well, the question is: Which parts _do_ need cooling? Most parts of a notebook are designed to run quite cool, also due to lower power consumption. Also a Flash disk also runs quite cool, no need for extra cooling. The only source of heat I can imagine would be the CPU. (At least of the computer used therefore) So using some low-power version like a 486 or an IDT C6/Winchip will help decreasing emitted heat. I ran a Winchip C6 (old one) at 50x2 = 100 MHz in a desktop system without even a heatsink (yes, bare CPU, no heatsink or fan) for some weeks under load, no probs. The Winchip only consumes half of the power than a similar (MHz) Intel Pentium MMX or AMD K6. (At 200 MHz, the IDT eats 10 Watts, Intel/AMD ~20 Watts) In my experience, if the system is intended to run only for some minutes, the CPU even at full pace hasn't enough time to overheat. Even if you need cooling, there's another idea. Basically, you need to transport the heat=energy away from the chip. On earth, you may take air as transport and dissolver. But why no liquid cooling? Simply fix some small tank (about some fluid ounces/millilitres) on top of the CPU, and fill it with water or alcohol. It shall absorb some of the energy emitted by the CPU due to contact. No big need for circulating it to the outer parts of the rocket, as it is only for some limited time. Basically you can calculate the energy needing to be absorbed... Modern CPUs have some known power consumption, so you can calculate the absorbed energy.. Regards Olaf Hoyer -------- Olaf Hoyer www.nightfire.de mailto:Olaf.Hoyer@nightfire.de FreeBSD- Turning PC's into workstations ICQ:22838075 Liebe und Hass sind nicht blind, aber geblendet vom Feuer, dass sie selber mit sich tragen. (Nietzsche) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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