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  #11  
Old 06-17-2015, 09:20 PM
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luke strawwalker luke strawwalker is offline
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Quote:
Originally Posted by Bill
"LANDING PAD (BALSA WOOD OR EQUIV)" Space age building material indeed.

Interesting off-center escape tower...the capsule must have very unbalanced mass distribution...


Bill


Yeah, that was the Convair design-- very strange looking indeed compared to the North American Apollo we know... This was back in the earliest planning stages of Apollo, studies and designs done before the Moon landing goal was announced. The plan for Apollo at that time was merely to loop AROUND the Moon, not land on it. At the time, the guidance and navigation problem was still looming VERY large-- nobody really thought it possible to navigate with the kind of accuracy necessary to hit the "reentry corridor" with enough accuracy for a blunt-body spacecraft, and there were a lot of concerns about shock-wave radiative heating and other not-well-understood hypersonic reentry effects that could burn a capsule up. The thought was that steep-angle heat shields would be necessary for lunar return velocities due to these hypersonic aero-effects and navigation uncertainties. Heck there were even LENTICULAR (disk-shaped, basically) designs for Apollo that were TRULY bizarre...

By the time the decisions on contractors was to be made, research had proven that navigation and corridor control was possible even at lunar distances (minor changes in velocity of a foot or two per second were all that was required at lunar distances for accuracy in hitting the corridor, whereas mid-course or late-course corrections required tens of feet per second of delta-v or even hundreds of feet of delta-v in the case of late corrections just prior to reentry, which of course greatly influenced the mass budget of the spacecraft, as a lot more fuel was required for trajectory/speed adjustments later in the trajectory than making minor "tweaks" to get on target at the beginning of the trajectory. NASA had also proved that it could track spacecraft accurately at lunar distances and adjust the course necessary to put the spacecraft where it needed to be to hit the Moon or go into lunar orbit, etc. and could do the same with a manned spacecraft about to set a trajectory for return to Earth, so the navigation problems were largely put to rest. At the same time, high speed reentries had proven that the perceived problems with high-speed reentries were not as bad as previously assumed, and that the "radiative heating" from hypersonic shock waves was not as severe as some thought, so that issue was put to rest, eliminating the need for steep-sided heat shields for the command module. Accuracy in hitting the window meant that lenticular and other irregular or high lift/drag ratio spacecraft designs were not required to "fly" the vehicle through reentry (and keep it from skipping out of the atmosphere or burning up coming in too steep) and so those designs were put aside.

That left the basic low-spherical-section blunt body heat shield, only with steeper side wall angles and no "forebody" like that on Mercury and Gemini (the cylindrical section at the front of the capsule) which Max Faget preferred for the Apollo design, and which North American and the other contractors were going to have to follow for their basic designs. All the more fanciful and interesting designs of the early days were discarded for the simpler, more straightforward and conservative design NASA preferred and that had worked well for Mercury and Gemini and stayed within their experience base.

Later! OL JR
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  #12  
Old 06-18-2015, 07:35 AM
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Very interesting information !
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Old 06-18-2015, 10:05 AM
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Originally Posted by ghrocketman
Very interesting information !


Glad you're enjoying it...

I just read one of my space books where they were interviewing Max Faget, among other space program leaders and luminaries... sort of an anthology from the NASA History Series... He talked a lot about the various committees and the pre-Kennedy lunar plans, and the evolution of the design of the Apollo shape and the various proposals and problems they were worried about and trying to address... and found most of them were needless worries once they got more experience and better test data...

Later! OL JR
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Old 06-18-2015, 03:37 PM
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Quote:
Originally Posted by luke strawwalker
...

Enjoy! OL JR

link to document i bad. Do you have a link to the NASA site?
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  #15  
Old 06-18-2015, 10:05 PM
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Originally Posted by Sunward
link to document i bad. Do you have a link to the NASA site?


No, sorry, I don't... try googling the title and see what that gets you...

I didn't post a link to the document... I downloaded tons of them over the years and sift through them periodically for stuff that might be "summarizable" and of interest to fellow rocketeers... this one could make an interesting FF scale model...

Lemme try to post the summary again... the studies themselves are FAR to large to post directly...

Later! OL JR

PS... it's a simple .txt file, open with any "notepad" program on your computer or "works" or whatever...
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  #16  
Old 11-05-2021, 01:19 AM
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Here are two "new" (to me) solid propellant Nova papers that I found this week:

http://www.gravityassist.com/IAF1/Ref.%201-47.pdf

https://www.airforcemag.com/PDF/Mag...1/1061solid.pdf

Also, the June and July 1963 issues of ANALOG Science Fact & Fiction ran a two-part article about Nova-size solid (June) and liquid (July) propellant launch vehicles. (I discovered this series by accident after receiving a copy of the June 1963 issue, which contained an illustrated story called "The Trouble with Telstar" (you can see it *here* https://www.gutenberg.org/files/306...9-h/30679-h.htm ), which involved a Saturn I-launched Dyna-Soar [which was an actual design proposal; that was why the Block II Saturn I vehicles had four large first stage fins--there was also a proposal for a Rogallo wing-recovered, reusable Saturn I first stage, illustrations of which I've seen in books from that period].) In other words, the equivalent of today's mostly-reusable Falcon 9/Dragon vehicle was proposed in the early 1960s, and the Dyna-Soar (X-20) was capable of achieving a large re-entry cross-range.
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  #17  
Old 11-05-2021, 01:17 PM
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75 feet in diameter, with 40 million pounds of thrust . . . Imagine viewing a night launch from Titusville . . . That would have been INTENSE !

Dave F.
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  #18  
Old 11-05-2021, 01:46 PM
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Quote:
Originally Posted by Ez2cDave
75 feet in diameter, with 40 million pounds of thrust . . . Imagine viewing a night launch from Titusville . . . That would have been INTENSE !

Dave F.
You can say that again--in the event of unannounced launches (military ones, say), a photocell detector or a seismometer could be used to alert "bird-watchers" of their liftoffs! Also:

Reusability isn’t necessarily the best way to go in order to have affordable space transportation, especially where heavy-lift launch vehicles are concerned; very cheap and simple expendable (discard-able)--*or* recoverable, but recycle-able-- large rockets could have the lowest payload cost per pound (or kilogram) in orbit. Both methods could also be combined, especially with very large solid propellant SLVs; the first stage (or stages), made with maraging steel motor cases, could be recovered and recycled, while the upper stages (where wound glass, carbon, or Kevlar fiber filament/resin motor cases' lighter weight would be particularly beneficial) could be discarded. Now:

The late Arthur Schnitt of The Aerospace Corporation (the aerospace engineering and policy think tank, rather like the RAND Corporation) developed the MCD (Minimum-Cost Design) design philosophy for launch vehicles and spacecraft. Instead of striving for maximum performance and minimum size & mass (the paradigm used for designing U.S. ballistic missiles and their derived launch vehicles), MCD trades cost on an equal basis during the design process. As a result:

MCD launch vehicles (and spacecraft) are larger and heavier than their maximum performance/minimum mass counterparts, but they are much cheaper, and require no specialty alloys or other materials for their production. (Indeed, in the late 1960s and early 1970s, Boeing [which actually built a prototype MCD first stage, minus engines] and the other launch vehicle contractors were gung-ho for MCD launch vehicles...*until* they realized that ordinary metal-working firms and ship builders could beat them at their own game, producing the simple pintle-injector, pressure-fed rocket engines and “double-bubble tankage” stage airframes [or simple, maraging steel-cased solid motor stages].) TRW built and static-fired a 250,000 pounds thrust pressure-fed, pintle-injector LOX/RP-1 MCD rocket engine (all of whose production, except the injector, they contracted out to a local, non-aerospace metal-working shop).

The engine was stored outdoors, with no special protection from the elements (they removed the dust sheets and swept out the remainder of the dust before firings), but it ran with no combustion instability problems (the Apollo Lunar Module’s Ascent Stage—whose engine *had* to work, unfailingly—used a much smaller, TRW-built N2O4/Aerozine-50 pintle-injector rocket engine [surplus examples of which powered Delta second stages in the 1970s]). The Soviet/Russian and Chinese IRBMs and ICBMs, and their derived launch vehicles, were designed using a paradigm similar to MCD, and they are cheaper and easier to manufacture and use than their Western “fine ladies’ watches” counterparts. (The Soviet aircraft designer Andrei Tupolev used that comparison to describe Western aircraft.) “You Americans design aircraft like fine ladies’ watches. Drop watch—watch break. We Russians build aircraft like Mickey Mouse clocks. Drop clock—clock stop. Pick up clock and shake—then clock work.” Also:

The MCD studies and experiments showed that, for first stages, such rockets are cheap enough (and durable enough) that their first stages can either be ocean-recovered via parachutes, or expended; the costs of both are very nearly the same (John London’s book “LEO on the Cheap” [a scan of it is linked-to below] goes into this, and more, in detail). Such rockets—at least their first stages—could be recyclable rather than reusable, with (as with bottles and cans returned for recycling) deposits being paid to bring them in for recycling. (MCD isn’t limited to rockets, either; Dr. Robert W. Bussard—famous for the fusion ramjet starship concept that bears his name—designed a fusion power plant reactor he called the Riggatron, which would use water-cooled, copper-wire wound electromagnets [no exotic metals or alloys]. He designed it to be cheap enough to be either refurbished or scrapped and recycled, after its service life limit was reached [like an incandescent light bulb, with which he compared this attribute of the Riggatron], so that even poor nations could afford to build these fusion reactors. Alas, he didn’t have enough money to build a prototype Riggatron, and the power plant reactor firms weren’t interested in simple, easily-duplicated designs.) Here are the links:

Google links citation list: http://www.google.com/search?ei=a7j...1.acFXNpL FLf8

“Minimum Cost Design for Space Operations” by Arthur Schnitt (of the Aerospace Corporation company & think tank, 1/26/97, by Foyle Publishing): http://www.quarkweb.com/foyle/mcd/MinimumCostDesign.pdf

“Low Cost Launch Vehicle Study” (generated by TRW for NASA, 1969): http://www.oldrocketforum.com/showthread.php?t=10764

“LEO on the Cheap: Methods for Achieving Drastic Reductions in Space Launch Costs” by John R. London III, Lt. Col., USAF (Air University Press, Maxwell AFB, Alabama, October 1994): https://upload.wikimedia.org/wikipe...Oonthecheap.pdf and http://www.dtic.mil/dtic/tr/fulltext/u2/a289106.pdf (page 85, TRW MCD engine, stages ~ page 200 - 210)

“AFFORDABLE SPACECRAFT: Design and Launch Alternatives” (U.S. Congress, Office of Technology Assessment, 1/1990): http://digitalcommons.unl.edu/cgi/v...xt=spacelawdocs

“TRW Pintle Engine Heritage and Performance Characteristics” by Gordon A. Dressler and J. Martin Bauer (AIAA paper 2000-3871) : http://www.rocket-propulsion.info/r...NTLE_ENGINE.pdf

(250 K and 650K pintle engines [no flight failure of a pintle engine])

“Low Cost Booster and High Performance Orbit Injection Propulsion Extended Abstract” by R. L. Sackhelm (TRW Space and Electronics Group): http://ntrs.nasa.gov/archive/nasa/c...19950002764.pdf

“A Review of United States Air Force and Department of Defense Aerospace Propulsion Needs” (Chapter 4, “Rocket Propulsion Systems for Access to Space”), The National Academies Press, 2006: www.nap.edu/read/11780/chapter/6#169

Sci.Space.Policy posting by William Mook, RE: The TRW TR-106 Pintle Injector Engine (including internal links): http://groups.google.com/forum/#!topic/sci.space.policy/AONW-HeTy1U

“The same basic pintle injector geometry has been tested at thrusts of 40,000 and 250,000 lb operating with N2O4/A-50; at 50,000 lb with LOx/RP-1; and at 40,000 and 650,000 lb with LOx/LH2.”
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