Date: Thu, 25 Jul 1991 14:09-EDT From: space-tech-request@cs.cmu.edu To: "~/st/lists/stdigest" Subject: Space-tech Digest #83 Contents: Kevin Driscoll GPS and Launcher Guidance Kevin Driscoll Ramjets Vince Cate Re: Ramjets Philip Fraering Sloshing propellant help needed Paul Dietz Hybrid rocket at MIT: "Project Olympus" Steve Hayhurst Radio Telescopes Joe Seanor Radio Astronomy ------------------------------------------------------------ Date: Wed, 29 May 91 18:30:36 CDT From: Kevin Driscoll To: space-tech@cs.cmu.edu Subject: GPS and Launcher Guidance We (Honeywell SRC) are working on several GPS/INS integrated navigation systems using both RLGs and FOGs. One which may be of interest to this group is the GGP which we are teamed with TI to make a GPS/FOG guidance system for DARPA (see AW&ST Feb 25, page 58). Specifications: 20 meter CEP worldwide (while jammed), 1 nmi/hr, $15K per unit in production, 35 watts, 300 cu in (shoe box size). Plans are for aircraft flight test in 1992, Minuteman missile test 1993, and then improvements to 0.5 nmi/hr and 100 cu in package. > I wonder how cheaply one could make a guidance system for a launcher. When GPS/INS guidance systems go into volume production for tactical missiles, smart bombs, and even cannon shells, they could get very cheap. There has been talk of building a GPS receiver using just 2 chips that fit inside the antenna. The wire coming from the antenna would contain digital position information. Our GG1308 RLGs are just 0.8 inches on a side. It is possible to build a 3 axis rate and acceleration sensor assembly the size of a golf ball. Add a few cu in for a processor and you have an GPS/INS small enough for these "high" volume applications. Volume is a major contributor to lower prices. Of course, it will be a few years before this type of volume is seen. > Isn't it possible to calibrate gyros for their drift rates? Or is it > impossible to predict the drift? This would have the effect of decreasing > the drift rate. > > I know that a lot of work has been done in the field of estimation of > state and error propagation--perhaps this could be moved from the system > level down to the component level. Kalman filters are already used to estimate and compensate for several sources of inertial sensor error. A new use is to feed raw information from skewed redundant sensors (such as our HEXAD RLG INS for the Boeing 777) into one Kalman filters to try "average out" the biases. The idea is to use the same redundancy for fault tolerance and for increased accuracy. ----- Kevin R. Driscoll, Senior Principal Scientist (612) 782-7263 FAX: -7438 DOMAIN: driscoll@SRC.Honeywell.com UUCP: {any smart host}!srcsip!driscoll POST: Honeywell M/S MN65-2500; 3660 Technology Drive; Mpls, MN 55418-1006 ------------------------------ Date: Wed, 29 May 91 18:41:37 CDT From: Kevin Driscoll To: space-tech@cs.cmu.edu Subject: Ramjets >> It might be necessary to use a normal jet engine to get the Pegasus up >> to the speed that a ramjet could work at since most seem to want to be >> going about Mach 1.5 to start. > Sounds like you're reinventing the space plane, sort of, with multiple > stages and unmanned. It's a good idea, but when a stage gets fairly > simple it's cheaper not to resue it, because the checking between > flights cost more in labor than you save in material. I have no idea if > a jet powered first stage falls under this heading, but I bet the rocket > stage does. How about diving the Pegasus after launch to get the speed and avoid adding extra hardware? Wouldn't the fuel used to regain the altitude be less than the weight of different engines or another stage plus their fuel? ----- Kevin R. Driscoll, Senior Principal Scientist (612) 782-7263 FAX: -7438 DOMAIN: driscoll@SRC.Honeywell.com UUCP: {any smart host}!srcsip!driscoll POST: Honeywell M/S MN65-2500; 3660 Technology Drive; Mpls, MN 55418-1006 ------------------------------ Date: Wed, 29 May 1991 20:49-EDT From: Vincent.Cate@FURMINT.NECTAR.CS.CMU.EDU To: space-tech@cs.cmu.edu Subject: Re: Ramjets It seems that the terminal velocity is less than the speed of sound. With air resistance being proportional to the velocity cubed and all, this is not hard to believe. Also note that the X-15 etc were not just dropped, they needed rockets to get going faster than sound. At some height (where the air is thin enough) this could work. I am not sure how high that is though, or how reasonable it is to try to get a big plane to fly that high. If it was only 65,000 feet or something it might be a good way to go. There are a couple big differences between adding ramjets to a Pegasus and building a spaceplane. The Pegasus upgrade could probably be done for less than $20 million and the spaceplane could cost more than $20 billion. The Pegasus upgrade might happen within the next 3 years and the spaceplane could easily be more than 10 years away. Also, most spaceplanes seem to like to take the jet engine and big wings (big enough for a loaded takeoff) into orbit, which reduces payload and increases costs. The German Sanger seems like the most promising design and it will still cost a lot and take a awhile. -- Vince ------------------------------ Date: Fri, 7 Jun 91 10:23:30 -0500 From: Fraering Philip To: space-tech@cs.cmu.edu Subject: Sloshing propellant help needed [I saw this on sci.space (which was a pretty neat trick, since I'm not reading news anymore) and I got permission from the author to post it here. - Phil] I have an application involving the dynamics of a spinning spacecraft (in this case ACTS) undergoing thrust from low- to high-earth orbit. The question concerns energy dissipation during the maneuver caused by sloshing of propellants. I have created a simple math model to describe the dynamics of this system, and I am modeling the sloshing propellants as pendulums. Each pendulum has two degrees of freedom (one responding to thrust, the other to spin transients), and has time-varying mass and length (due to the depletion of propellants). If the spacecraft is assumed to have no center-of-gravity offset of thrust misalignment, and if each propellant tank is depleted at the same rate, then all pendulum DOFs can be treated as having the same response. What I am looking for are references that describe the means of selecting pendulum mass and length, given shape of tank, percentage full, and flight conditions. There has been work done for launch vehicles by the folks at the Southwest Research Institute, but I would like, if possible, to hone down the literature search before it begins. Can anyone help me locate some info on this subject? I would be most grateful, and would be glad to summarize if I get more than one relevant response. Follow-ups directed to sci.engr, due to the technical nature of the subject. RG "talk.politics.space" - its time has come. ------------------------------ Date: Thu, 18 Jul 91 08:23:11 EDT From: dietz@cs.rochester.edu To: space-tech@cs.cmu.edu Subject: Hybrid rocket at MIT: "Project Olympus" This message appeared on the net, so I sent a query, the answer to which follows... > From: larrys@bard (Larry Smilg) > Newsgroups: rec.models.rockets > Subject: large rocket waivers > Keywords: waiver hybrid > Message-ID: <1991Jul17.214743.10399@athena.mit.edu> > Date: 17 Jul 91 21:47:43 GMT > Sender: news@athena.mit.edu (News system) > Reply-To: larrys@bard.mit.edu > Organization: MIT I am working on an MIT Aero/Astro program called Project Olympus. Our goal is to use hybrid rocket technology to design and build a rocket capable of launching a small (5 lb.) payload into orbit. Hybrid engines use gaseous or liqiud oxidizer with a solid fuel charge. Anyway, we want to build a small hybrid rocket and launch it. A while back I remeber seeing that an FAA waiver is needed to launch any rocket weighing more than one pound. How do I obtain one of these waivers? Also, I would be interested in learning of any common model rocket launch sites in the Boston area. Please respond by E-mail with answers OR questions (I love talking about Olympus) to: larrys@bard.mit.edu -- W. Earle - "Oh! What have you got there Leo? Oh my! No! Please... don't! I beseech you Leo! Have mercy!" Leo - (click) "AAAAAAAAAAAARRRRRRGGGGGHHHHHH!!!!!" (twitch) -- Larry Smilg larrys@bard.mit.edu ======================== >From larrys@bard Wed Jul 17 22:24:11 1991 >Received: from BARD.MIT.EDU by cayuga.cs.rochester.edu (5.61/u) id AA03662; Wed, 17 Jul 91 22:23:59 -0400 >Received: by bard (NeXT-1.0 (From Sendmail 5.52)/NeXT-2.0) id AA02045; Wed, 17 Jul 91 22:23:20 EDT >Date: Wed, 17 Jul 91 22:23:20 EDT >From: larrys@bard.MIT.EDU (Larry M. Smilg) >Message-Id: <9107180223.AA02045@bard> >To: dietz@cs.rochester.edu >Subject: Project Olympus Well, here are the answers to your questions: (1) What fuel and oxidizer would you use? We are using Polybutadiene as our fuel. We are not metallizing it at all. Our fuel gets hot enough already, and nozzle throat erosion is a major concern already. Surprisingly, in some tests, we have been getting a whitish BUILDUP on the nozzle. We do add a bit of carbon to make it absorb heat better. Our current test engine is using GOX as the oxidizer. We plan to go to LOX soon. We are just waiting for a few parts so we can completely test the pressurization system with liquid nitrogen soon. The most maddening of those is a 20 cent plastic ball for the flowmeter. It was ordered 2.5 weeks ago!!! (2) Guidance? I'm not exactly sure on the guidance system we will be using. I have heard rumors that we might be trying to use a sun sensor guidance system. I don't know much about that area, but this close to Draper, I'm sure we will come up with something. (3) How do you plan to vector thrust? Our plan for TVC is to gimbal the nozzle - sort of. It will be mounted on flexible rings and use two actuators attached to the nozzle to move the nozzle. This system isn't easy - insulation ad sealing are the two major concerns. (4) How will the oxidizer tank(s) be pressurized? A pressurized helium tank. (5) How are the nozzles to be cooled? Nope. (6) What sort of testing program do you have planned? We've been firing a small (~20 lb. thrust) engine for almost a year now. It uses the PBD and GOX system I described above. Our runs have been five to ten seconds long. We have been getting data on regression rates and port burn shape. The data are encouraging; our regression rate is better than any other previously gotten - I think. Our next step is to test with LOX, which we should be able to do before the end of the summer (If I get that damn ball!). After that, we want to build a ~400 lb thrust motor. That motor would be the approximate size of the engine on our first rocket, which would be a one stage suborbital flight. That rocket we hope to fly in the summer of '93. After that, we will start building the three-stage-to-orbit rocket. Hey, wait, no fair! You didn't answer any of my questions!!! Larry Smilg larrys@bard.mit.edu ============================== Enjoy! I hope Larry did not mind my posting this... Paul ------------------------------ Date: Wed, 17 Jul 91 09:23:00 PAC From: HAYHURST@idui1.csrv.uidaho.edu To: SPACE-TECH@CS.CMU.EDU Subject: RE: RE: Radio Telescopes I hope this didn't already arrive and get distributed; if so SORRY! Victor Limary sent out a note asking about Radio telescopes: ========================================================================= Date: 17 July 1991, 08:35:36 PAC From: HAYHURST at IDUI1 To: VCL at BBX.BASIS.COM Subject: Radio Telescopes Good morning: I don't remember the exact date, but back in approx. 1985-87, ASTRONOMY magazine had an article on cheap radio astronomy. As an example, the author built one telescope on a base of 3' X 5' plywood covered with chicken wire, with 2" X 4" legs. He reported that he could record the Sun, Jupiter, and some of the brighter radio objects in the sky. Check the back issues section. Also, if you want to send me an address, I could (once I have finished unpacking from my move) snail mail you copies of the materials I have collected. Some of it is pretty dated, but might still be useful. Hope this helps... - Steve H. ====================================================================== ? STEVE HAYHURST COLLEGE OF AGRICULTURE UNIV. OF IDAHO, MOSCOW ? ? (208) 885-7160 IDDINGS AGRICULTURAL HAYHURST AT IDUI1.BITNET ? ? COMPUTER APPL. SCIENCE BUILDING IDUI1.CSRV.UIDAHO.EDU.INET ? ? SPECIALIST ROOM 307 129.101.112.1 - IP ADDRESS ? ?======================================================================? ? ---\ \ ? ? \\\ ---(oo )^---^. "COW DISCOVERS METHANE" ? ? >>>>\O/(____)) ? ? /// ----- / /;;/ ? ====================================================================== ------------------------------ Date: Wed, 24 Jul 91 13:33 EDT From: Seanor@DOCKMASTER.NCSC.MIL Subject: Radio Astronomy To: space-tech@CS.CMU.EDU If anyone has information on Radio Astronomy and how to get started in it I would like to know about it. I think this would be a great project for my nephew and I this summer, but of course, I'm talking about CHEAP radio astronomy! Thanks for any help. Joe DOCKMASTER.NCSC.MIL ------------------------------ End of Space-tech Digest #83 *******************