[ERPS] Re: ERPS-list Digest, Vol 20, Issue 1

Gentlefolk, Sorry I missed it. I had Thrusday on my mind and checked email too late. --Best, Gerald ___ ERPS-list mailing list ERPS-list@lists.erps.org http://lists.erps.org/mailman/listinfo/erps-list

[ERPS] Apollo Hardware Location2

Gentlefolk, We know something more about the fate of the remains of the Apollo 13 LM because it had an RTG attached to it. --Best, Gerald From: http://www.seds.org/spaceviews/cassini/rtg.html "The Apollo 13 lunar module still had its RTG attached when it burned up over the Pacific Ocean u

[ERPS] Apollo hardware locations

Gentlefolk, This is from: http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_tables.html --Best, Gerald (View this in a non-proportional font such as Monaco 9) Impact Sites of Apollo LM Ascent and SIVB Stages Impa

[ERPS] Re: Orbital Mechanics

In a message dated 04/12/31 12:00:12, [EMAIL PROTECTED] writes: << So what's the required delta-V for a "minimal mothball orbit-raising mission" - i.e., boost it to an orbital altitude such that the orbit won't decay any time soon, and it can safely be powered down and allowed to "go passive"

[ERPS] Orbital Mechanics

Dear Ejay Hir and all, I've a somewhat better view of Bate, Mueller, and White, than Henryâ probably because I'm so used to it and haven't seen the other texts Henry mentions, though I should look at Chobotov. I was acquainted with Vladimir Chobotov back when he worked for Aerospace Corp., I w

[ERPS] Thursday Meeting

Gentlefolk and Julie, esp. Apologies, but I won't be able to attend the meeting tonight. Gayle reminds me that we have Opera tickets. See you in two weeks. --Best, Gerald ___ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/lis

[ERPS] Spaceship One Altitude

In a message dated 04/10/04 12:00:44, [EMAIL PROTECTED] writes: << Unofficial altitude was 368,000 feet. >> 112.2 km, significantly over the X-prize minimum! --Best, Gerald ___ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/lis

[ERPS] Re: Moon rocks.

<< "...irreplaceable national resources..." >> Gentlefolk, Eventually moon rocks should be a very replaceable resource--literally dirt cheap. It's only a matter of when. Keep the faith. ;-) As I understand, neither an individual nor a government can claim an entire astronomical body, but cla

[ERPS] ERPS/Worldcon

Gentlefolk, Please bring any publicity material which you would like me to take to the World Science Fiction convention to the next meeting (26 Aug). Thanks. --Best, Gerald ___ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/lis

[ERPS] Re: Tip nozzle paradox

Apologies for not changing the title on my last post on this. <> Okay, in an "ideal" drag=free system, thrust increases with centrifugal force as chamber pressure, etc., increase. The specific kinetic energy of the propellant in the inertial frame must increase as it flows to the tip engines,

[ERPS] Re: ERPS-list Digest, Vol 10, Issue 16

<< Now from momentum considerations you can show that the tip speed should be equal to the exhaust velocity- in this case ~200 m/s >> I may be missing part of this scenario, but there seems no reason for rotor tip speed to equal exhaust velocity. I would think rotor tip speed would increase un

[ERPS] Re: Multiple engines

Gentlefolk, If memory serves, in some Russian multiple nozzle designs, the engines are all mounted rigidly on a single frame along with the pump and the whole assembly is gimballed. This would have the advantages of robustness and simplicity. --Best, Gerald

[ERPS] ERPS BayCon Party

Gentlefolk, Due to various conflicts, the Heinlein society will need Sunday night, and CONTACT Saturday night. The revised schedule will now have room 257 available to ERPS on FRIDAY night 28 May. CONTACT will provide plates, dishes, etc., but we'll need a couple ERPS people to set up and b

[ERPS] BayCon Party Room

Gentlefolk, As some of you are aware, I volunteered to secure a party room to be used one night eacy for CONTACT, ERPS, and the Heinlein Society at BayCon (28-31 May 04) I've received confirmation that we do, indeed, have a room for Friday, Saturday, and Sunday night; it will be room #257. Be

[ERPS] Plume Shadow Photography

Gentlefolk, Suggest a fairly bright monochromatic source if you can find one; index of refraction variations bend different wavelengths by different angles. The light should be some distance from the plume and the shadowboard should be as near as practical. It may help to be able to vary the

[ERPS] Re: ATFE...

Gentlefolk, For a do-it-yourself antiaircraft rocket, the guidance system would seem to be an order of magnitude or two more difficult to concoct than the rocket motor. This suggest that it would be far more productive for ATFE to keep track of laser gyros and IR focal plane arrays than worryi

[ERPS] reusable capsule

Gentlefolk, << NASA's not used to thinking in those terms, but there's no particular reason why capsules can't be reusable...>> NASA isn't the only game in town. http://www.spacedaily.com/news/shuttle-03r2.html the U.S. first reused a space capsule 36 years ago! The capsule used on Gemini 2, an

[ERPS] Silicon Hiatus

Gentlefolk, I talked to some of you earlier about doing something for SiliCon. We are told now that the next Silicon will be in Oct. 2004, not 2003. --Best, Gerald ___ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/e

[ERPS] Re: Casualties/Launch

Gentlefolk, << the chances of going bang goes down with launch experience, not up! >> For initial experimental operations, yes, but this learning curve can peak early. With long term routine operations, there's a tendency for complacency to set in, pressure to cut corners to save money (until

[ERPS] Casualties/Launch

Gentlefolk <<...less mass == [presumably] less chance of casualties per launch, even if that means you launch more often to launch the same total mass>> My thought is that this is scenario dependent, both on the technology and the insurance pool arrangements. As a military guy, I'm aware tha

[ERPS] HTHL vs VTVL

Gentlefolk, With a GLOW of around 200 tons and a mass ratio of 20+, my feeling is that an orbital vehicle is an entirely different thing than a fighter or an X-prize vehicle in the HTHL discussion. If a single vehicle, I don't think you're wheels up at anything like 70 m/s; the wings to do tha

[ERPS] Re: Columbia rescue mission

<> I didn't realize Atlantis was that close. Using it was clearly the best option, and using an updated tank, not really that risky, all things considered. This begins to look very dark indeed. --Best, Gerald ___ ERPS-list mailing list [EMAIL PROT

[ERPS] Columbia rescue mission?

<> One of the most frequent errors I encountered in space operations was the knee-jerk reaction that something wasn't practical or couldn't be done because the equipment "wasn't designed for that." The people making those kinds of objections cost many valuable hours spent in meetings with high

[ERPS] Columbia rescue mission?

<> Not necessarily. Numerous launchers, including several ICBMs could deliver payloads to the Columbia's orbit in a pinch to extend its mission. Eventually, another shuttle could have been readied, or a Russian launch site been moved south for a rescue mission. A lot of Apollo 13 type engin

[ERPS] Gas Core

<> Hmm, it would seem the first instance (unavoidable) would at least preclude worrying about the second...;-) --Best, Gerald ___ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list

[ERPS] Gas Core/Nerva

<< The last time this [Gas Core nuclear] was seriously worked on -- I heard a talk by Steve Howe (of LANL) in 1996 -- they weren't sure which was best, although they seemed to be favoring a concept with a toroidal core. >> Well, something in '96 updates me on this subject ;-) I didn't realize

[ERPS] Gas Core/Nerva

Gentlefolk, I'm afraid I've been kicking around the advanced propulsion community too long and assume everyone's heard of everything, sorry. The gas core nuclear concept was essentially a radially symmetric drum. A uranium-bearing gas (Uranium hexafluoride, in my memory, but perhaps Henry has

[ERPS] Solar/laser thermal rocket performance

Gentlefolk, At the AF rocket lab at Edwards AFB, almost 20 years ago, we were building a rhenium tube heat exchanger for a solar thermal rocket, expecting to get 9 to 10 km/s exhaust velocity (=isp) with hydrogen. If memory serves, results approximating that were achieved in testing a few years

[ERPS] Lunar impact conf.

Gentlefolk, I've extracted this from a JPL media release. 20 Feb O2. <> ___ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list

[ERPS] Re: ERPS-list digest, Vol 1 #609 - 7 msgs

<< you will have to evaporate a smaller mass of water ... total system masses close enough to be a wash. >> <<< $0.25 clink!!! >>> ___ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list

[ERPS] Laser rocket

Gentlefolk, << ...how efficient can you absorb laser light and turn it into heat >> One also needs to turn the heat into vehicle kinetic energy. The light to heat efficiency should actually be much higher than with transmission and spillover losses the main worries; say around 70%. Heat to v

[ERPS] RLV ballpark economics

Gentlefolk, << That puts launch costs between $25/lb and $100/lb to LEO. Anyone think that's feasible?>> I've seen curves that run down to those kinds of costs at large mission models. I think you start to get in that ballpark when the cost of the fuel becomes significant with respect to the

[ERPS] Turnaround operations

Gentlefolk, Brainstorming Since the vehicle is unlikely to have shuttle-like cross range, it should be designed to fly from where it lands. I think a mobile service vehicle is a necessity. Since by definition, the engine thrust support structure (TSS) must take something like 1.5 times t

[ERPS] Turnaround Crew

Gentlefolk, One imagines that, like most other thing, turnaround time would be subject to cost-benefit trades, design, and experience. There will likely be a somewhat soft physical limit in how rapidly one can push fuel and oxidizer into the vehicle, but by the standards of an operational

[ERPS] Re-entry Configuration

Gentlefolk, This is possibly an old topic, but I'd like to hear what people think. If one assumes that that vertical takeoff, base-first reentry, and vertical landing is the simplest and lightest way to make an SSTO, what's the best way of dealing with the engines on reentry. Several possibili

[ERPS] Turnaround Crew

Gentlefolk, I concur with Henry, big trunaround crews aren't needed, even with lox. However, the system has to be carefully designed to minimize the amount of labor needed for turnaround. One of the really neat things about DCX is that its powered landing system was the same one that gets it

[ERPS] How to avoid NASA pitfalls.

Gentlefolk, << How exactly on scaling up could ERPS avoid NASA's pitfalls? >> My thoughts are KIS and small and focus on demonstrating a fully reusable Earth to LEO system. Avoid all secondary agendas by not taking or soliciting any money other than no-strings-attached grants and donations.

[ERPS] Comparative Risk

Gentlefolk, I think number of fatalities per mission is the fairest comparison. If endurance is to be considered, it should be per hours in space, not miles covered. Another reason to dislike wings is that they are big targets for space junk. The closer to spherical your spacecraft can be,

[ERPS] Tire

Gentlefolk, Does anyone care to estimate what the burst pressure was on the tire and how hot it would have had to get to exceed it, noting that the burst pressure at high temperature is likely lower than at normal operating temperature. --Best, Gerald _

[ERPS] Re: Columbia

Gentlefolk, With the caveat that it's still early in the investigation, I've taken a stab at anticipating some of what might eventually be done in response to the disaster. Some of these, I realize, will be a politically unpalatable goring of sacred cows within NASA and perhaps wishful thinking

[ERPS] G. Harry Stine

Gentlefolk, << Other than that, I always read his articles in Analog (or was it Galaxy?). >> It was Analog. He did the "Alternate View" column, alternating with John Cramer. --Best, Gerald ___ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps

[ERPS] Columbia

Gentlefolk, --People watching NBC this morning heard Buzz Aldrin read some lyrics from Jordin Kare's "Fire in the Sky." --Wings are dead weight on spacecraft and the shuttle's Mass/Area is still too high. --Concerning big ice chunk damage from launching when it's too cold. If this turns out to

[ERPS] Monatomic Hydrogen

Gentlefolk, For your information, here is a table based on some of Dr. Bob Frisbee's (yes, he's related to the Frisbee Pie Plate company family which used to throw the pie plates that evolved into the toy) work at JPL. Bob Frisbee is still doing his thing at JPL. I added to the table and incl

[ERPS] Fwd: Vandenberg Rocket Launch This Evening

Gentlefolk, This news came via the Antelopve Valley Astronomy Club. --Ad Astra, Gerald --- Begin Message --- Vandenberg launch this evening - Look west around sunset. - Tom Delta 2 Jan. 12, 2003 4:45 to 5:30 p.m. PST A commercial Boeing Delta 2 is to carry NASA's Ice, Cloud and land Elevation Sa

[ERPS] Variable ISP for liftoff

Gentlefolk, Robert H. Goddard has a 1930's patent for what we would call a turbo-fan driven by rocket exhaust to "dilute" ISP for lift-off. It's on display (as of three or four years ago) in a cabinet by the entrance to the Goddard Museum at Roswell NM (essentially, the workshop where he built

[ERPS] Speed of gravity

Gentlefolk, Ditto to most of what Henry and Ian said, though there is still some legitimate physics being done on non-geometrical interpretations of the general relativity equations in efforts to create a self-consistent mathematical theory embracing both relativity and quantum mechanics. Don'

[ERPS] Apollo 17 memory correction.

Gentlefolk, It is scary how a memory that seemed accurate a couple of days ago, becomes uncertain the next day and seems wrong today. Today, I think the name of the head of the Vela Hotel office in the STC back in the early 70's was something more like "Wyoma" or "Wynona" Klare, not Norma, and

[ERPS] Apollo 17

Gentlefolk, Thirty years ago, I had just began work as the "Interrange Operations Officer" in the Network Control division of the AF Satellite Test Center (the "STC," the big blue cube on highway 101). Part of my duties involved overseeing the transmission of orbital elements of the VELA HOTEL

[ERPS] Vibrations

<< It's got a full tank of nitrogen and/or peroxide between it and the engine; hard to see how valve chatter pressure waves would survive undamped through all that gas/liquid. Also wouldn't the chatter be above several Hz? >> To damp, something has to absorb energy. If there's nothing in the

[ERPS] Vibration testing

Gentlefolk, If you have the time and money, you build a hanger queen and vibrate that a couple of times worse than you think the flight article will see. Then, if anything comes loose, you redesign it, or its assembly procedures, inspections or all of those so it won't come loose on the flight

[ERPS] Oxide Catalysts

Gentlefolk, A quick web search came up with this intriguing snippet from Paul Sabatier's 1912 Nobel Prize lecture: At a temperature of between 250° and 300°C powdered copper very conveniently brings about dehydrogenation of primary alcohols into aldehydes and of secondary alcoh

[ERPS] SiliCon (SF convention in Foster City this weekend)

I have a room on the "party floor" Friday, Saturday & Sunday (dead dog time). If ERPS would like to share munchie expenses, I'll share space. For prosepctive attendees, the room rate is "only" $79/night and, as I understand, is still available. There were problems with the hotel website ma

[ERPS] Antimatter...

Gentlefolk, I'm not familiar with the Mars mission application, but the idea of using antiprotons to trigger fission/fusion reactions for nuclear pulse propulsion originated (as far as I know) with Dr. Gerald Smith, then of Penn State, who was part of the Air Force effort I helped manage in th

[ERPS] Re: Units

Gentlefolk, For what it's worth, and understanding that some parts still have to be ordered in English measure, I lean toward following the AIAA's lead and keeping everything else in SI units. It seems to be borrowing trouble not to do so. --Best, Gerald __

[ERPS] Plan of Attack

Gentlefolk, On choosing which problem to attack first, I think one wants to score the problems with respect to potential impact on the overall project goal, then multiply that by the liklihood of achieving a solution with existing resources (not quite the inverse of "difficulty," but close), t

[ERPS] Re: optical encounter missions

<< An extra 1km/s near Earth translates to nearly 5km/s >> 5 km/s hyperbolic excess velocity is none too little. We're lucky if we see the things coming before closest approach at all. A day or two, not a week, is about what we'd get. --Best, Gerald ___

Re: [ERPS] optical encounter missions

<< If you're talking about a flyby as the asteroid passes -- so the probe just needs to be in the right near-Earth place at the right time -- then a reasonable rule of thumb is to take an orbital delta-V and add 3km/s. Henry Spencer >> D

[ERPS] Re: ERPS-list digest, Vol 1 #352 - 6 msgs

Gentlefolk << The positional data you'd get from a flyby is not that helpful -- ground-based radar will do better. >> An exception to this would be if there's a high resolution camera on board. Pictures of the body against the background star field are very useful in astrogation. Such "naviga

[ERPS] Clusters

Gentlefolk << ...while still being able to throttle back sufficiently by shutting down engines. How does/did Atlas accomplish this with only 2 engines ? >> The classic Atlas had three engines, two boosters outboard (later dropped) and a sustainer on the center line. If memory serves, only the

[ERPS] Cute Asteroid

Gentlefolk, <> The high inclination could easily be the result of an Earth encounter. On the other hand, lots of main belt asteroids share that inclination. Spectroscopy should settle the rocket body question. With digital cameras getting so tiny and the NEA catalog getting into shape, I'm

[ERPS] Cute Asteroid

<<> Anyone care to guess what a return delta-v would be? It looks to me to be > miniscule, 100m/s? Certainly under 1km/s I would think.>> <> If by "return delta v," we mean a sample return, this could be quite low. The inclination difference means only that one would have to time the Earth en

Re: [ERPS] Ice

Dear Ian and all, <> I hadn't considered aerodynamic heating melting the surface of the icicle, but a layer of aerogel might take care of that. Anyway, I think that if there were some melting, that there would be enough vapor pressure to keep the mylar tight. It doesn't tear easily at all.

[ERPS] Ice

Gentlefolk, << ...friction with interstellar matter >> Theres not enough of it for any meaningful friction or force. Even over the area of a proposed Bussard ram scoop, the drag is but a few newtons. You'll get spallation and erosion, but no meaningful force even at fairly high Lorentz fac

[ERPS] Re: ERPS-list digest, Vol 1 #328 - 12 msgs

Gentlefolk, << it appears that HTP gets inactive w.r.t. most catalysts when it gets cold >> As most explanations of catalytic processes depend on the reactants being mobile enough to meet on the catalytic surface, this doesn't surprize me. --Best, Gerald __

[ERPS] Propellant papers

Gentlefolk, I've picked up three preprints of possible interest at this week's AIAA/ASME etc Joint Propulsion Conference. Towards Green Propulsion for Spacecraft with ADN-Based Monopropellants Anfio, Gronland, and Bergman. Sweedish Space Corp. An Investigation of a Low-cost HTP/Kerosene

[ERPS] Shuttle tank bottom

<< Anyone know why the main tank has a rounded bottom .vs. cone? My guess was the added mass and difficulty flowing the H2 into the shuttle overwhelmed the potential lower drag. >> Dan and all, My guess would be that it was a matter of minimum structural mass. Tank bottoms want to be rounded.

[ERPS] Drag losses...

Gentlefolk, << even a vague approximation to the shape of the curve is much better than trying to pretend it's flat. >> This is a fundamental for "fuzzy logic" of the sort that keeps video camera fields steady and many other things. Interesting to see it come up in this context. Bef

[ERPS] Re: Drag losses...

Gentlefolk, <<... delta-v 9000 m/sec >> The canonical figure is 10 km/s, despite a paper about ten years ago that fooled me and some others. Schemes to make any significant dent in that have born little fruit. If you accelerate faster to avoid gravity losses, your engines are heavier a

[ERPS] Re: Too Late to Duck

Gentlefolk, I grabbed a graph off the web << http://www.au.af.mil/au/2025/volume3/chap16/v3c16-1.htm#The Threat>> and traced it in ASCII below. If I believe it, a Tunguska-sized body should actually hit us every century or so, about a 1% chance each year. At a miss distance of rmin = 120,000

[ERPS] Re- Crowding in space

Gentlefolk, << Said parameters, IIRC, define the orbit, but not where in the orbit the bird will be at any given moment. Not very useful. >> Actually, the reduced set is very useful to those attempting to fit an observation to an orbit for either orbit determination or recognition purposes.

[ERPS] Flying nukes.

Gentlefolk, The reactor for a nuclear powered aircraft still sits cooling down out in the barrens Idaho National Engineer Laboratory (INEL; it's vast, mostly unpopulated, and is where, among other things, the damaged core of the Three-mile Island plant came to rest). I was told that what kill