From: skunk-works-digest-owner@mail.orst.edu To: skunk-works-digest@mail.orst.edu Subject: Skunk Works Digest V5 #448 Reply-To: skunk-works-digest@mail.orst.edu Errors-To: skunk-works-digest-owner@mail.orst.edu Precedence: bulk Skunk Works Digest Friday, 6 October 1995 Volume 05 : Number 448 In this issue: Re: Skunkstock '95 -- participants Composites, Metals, and Beryllium Titanium, Tungsten & depleted Uranium tungsten See the end of the digest for information on subscribing to the skunk-works or skunk-works-digest mailing lists and on how to retrieve back issues. ---------------------------------------------------------------------- From: Mike Beede Date: Thu, 5 Oct 1995 12:33:52 -0500 Subject: Re: Skunkstock '95 -- participants Say, I never though of posting this before, but remember that SR-71 pilot's manual that's out there for $100? I was at Zenith Books a month ago for one of their sales, and they had three copies for $50 apiece. All the ``damaged'' (e.g., returned) books were 1/2 price. I picked up that Navy airships book for $17, for instance. These were still shrink-wrapped, and seemed to be in perfect shape. Anyway, they have periodic sales (they had a nice car show in conjunction with this one -- they're also Motorbooks -- and all free free free!), so if anyone wants one of these and ever gets to the Osceola WI area (about 45 minutes from St. Paul MN) they might want to stop by. Check if there's a sale first, though -- they don't usually do in-house retail. Mike ------------------------------ From: "Terry Colvin" Date: Thu, 05 Oct 95 11:46:02 EST Subject: Composites, Metals, and Beryllium Forwarded from the SPACE TECH list: Date: 2 Oct 1995 01:06:02 GMT From: "William H. Mook, Jr." Subject: Aurora & Blackbird I believe that as part of the National AeroSpacePlane project Beryllium was looked into as a structural component to separate thermal protection systems from tankage. Advanced Metal Matrix Composites, seem to be a better choice though. Any solid you can make with metal, you can make like a sponge. Now, spongy metal is only about half as strong as solid, depending on how you form it. But, spongy metal weighs 1/10 to 1/100 as much as solid, since its mostly empty weight. So, spongy metal is really strong per unit weight. This is what you want for stuff you build spacecraft out of. As far as endothermic fuels, I do recall reading a lot about Lithium wire being used in experimental ram/rockets. Lithium is a solid, burnt in a hydrogen atmosphere to form lithium hydride. Then the lithium hydride burns in oxygen. One of the problems with a jet engine is that you have to slow the air down to something less than flames propagate. Otherwise, your engine flames out. That's why supersonic combustion ramjets are necessary for attaining orbital speeds. You don't have to slow everything down. One way to achieve supersonic combustion is to eject your propellant at high speeds. When you start thinking along these lines you end up with an external combustion system. Here the shape of the vehicle is such that you eject gaseous lithium hydride into the oncoming air, and it detonates and the expansion waves propel you along. Sort of like squeezing a pumpkin seed between your fingers. Also, to limit the thermal load on your airframe, you might want to consider intermittent combustion, or a pulse type operation. That way you transfer momentum, without giving the plasma much time to transfer heat. Momentum and heat propagate in different ways. So, pulsed thrust is really great. This is different than pulse jets from WWII. The old pulse jets had a resonating combustion chamber and exhaust tube. Vibrating valves in the front of the combustion chamber vibrated in resonance with the exploding pulse. You had pulsed combustion that worked in time with the valves. The valves were little mechanical flaps. But you could do a SCRAMJET the same way, but here the interacting shockwaves form regions of compression withing a combustion chamber, outside the aircraft. At least that's a layman's description of things, without recourse to Hugionot's Equations. - ------------------------------ Date: 2 Oct 1995 18:55:22 GMT From: Robert Alan Zingarelli Subject: Aurora & Blackbird In article <9508298123.AA812388600@CCGATE.HAC.COM>, sranderson@ccgate.hac.com writes: |> >RAND Corporation report RM-1642 and article P-871. Has beryllium |> >been used to any great extent. I understand it was a successful |> >material for missles, but what about planes? |> I'm not a materials fella, but I do know beryllium is very often used in |> satellite structures. I understand that it is also used in missles, |> high-speed aircraft (no specifics), spacecraft (the Shuttle), as well as |> automobiles. Beryllium possesses several desirable properties...light, good |> elasticity, thermal conductor, nonmagnetic, etc. Caution though, Beryllium |> is toxic and should not be worked or handled by the uninitiated. Never |> taste it! Smells great too! [CLUNK] - ------------------------------ Date: 2 Oct 1995 23:28:58 GMT From: Kathleen Zurhellen <102523.416@CompuServe.COM> Subject: Aurora & Blackbird The fact that beryllium costs about $4,000 per kilogram couldn't help. - -- KZ ------------------------------ From: "Terry Colvin" Date: Thu, 05 Oct 95 11:52:04 EST Subject: Titanium, Tungsten & depleted Uranium Forwarded from the SPACE TECH list: Date: 30 Sep 1995 03:11:59 GMT From: Ward Burrows Subject: Hello Aurora, Goodby Blackbird Simon Rowland writes: >OK then. >Titanium has a melting point of 1943 C. >Tungsten has a melting point of 3680 C. >Am I missing something? > Even if only an outer shell was tungsten, or it was a >tungsten/titanium alloy, there's a bonus here... You're missing a mass penalty there. Tungsten is a very strong metal, with the highest melting point of any element, but it is also quite dense! Let me put it this way: You know the armor piercing hypervelocity rounds the military uses? When they can't get (or don't want to use) depleted uranium, they use tungsten instead... the stuff has a higher specific gravity than mercury. An aircraft or spacecraft made of tungsten would be very sturdy, but you'd need fusion drives or something equally potent to get it off the ground. :-) - -Ward. Ward Burrows What's the best way to break up a meeting wardb@alumni.caltech.edu of Werewolves Anonymous? - moon them. ------------------------------ From: Robert.Herndon@Central.Sun.COM (Robert Herndon) Date: Thu, 5 Oct 1995 14:11:24 -0600 Subject: tungsten Another difficulty with Tungsten (Wolfram, for most of the non-U.S. world...) is that unless it's extremely pure, it's non-malleable, non-ductile, and very brittle. And its refractory properties, while desirable for many things, makes it very difficult to work. Beryllium is, I believe, also used in fluorescent light-bulbs. One of the phosphors is beryllium oxide; I have been told that cuts from fluorescent bulbs are particularly nasty because they heal very slowly and poorly due to it. Terry Colvin comments on matrix materials being better than beryllium. Is there any reason not to use beryllium matrices? /r ------------------------------ End of Skunk Works Digest V5 #448 ********************************* To subscribe to skunk-works-digest, send the command: subscribe skunk-works-digest in the body of a message to "majordomo@mail.orst.edu". If you want to subscribe something other than the account the mail is coming from, such as a local redistribution list, then append that address to the "subscribe" command; for example, to subscribe "local-skunk-works": subscribe skunk-works-digest local-skunk-works@your.domain.net To unsubscribe, send mail to the same address, with the command: unsubscribe skunk-works-digest in the body. Administrative requests, problems, and other non-list mail can be sent to either "skunk-works-digest-owner@mail.orst.edu" or, if you don't like to type a lot, "prm@mail.orst.edu A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace all instances of "skunk-works-digest" in the commands above with "skunk-works". Back issues are available for anonymous FTP from mail.orst.edu, in /pub/skunk-works/digest/vNN.nMMM (where "NN" is the volume number, and "MMM" is the issue number).