Aeronautics Industry Aeronautics Industry    FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Dyna-Soar/Atlas-Centaur Goto page Previous  1, 2, 3, 4, 5  Next          Aeronautics Industry Forum Index -> Aeronautics Industry View previous topic :: View next topic   Author Message Henry Spencer Guest Posted: Sat May 05, 2007 9:22 am    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn In article <1178144941.717578.46950@n59g2000hsh.googlegroups.com>, Neil Gerace <geracen@webace.com.au> wrote: Quote: IIRC the reason there is no ejection seat on Mercury is because there is no convenient place to put roof panels that can be blown out before the seat fires. There are such places in Gemini but not in Apollo. Is this correct? No, I'm afraid not. Mercury could have been designed with such an escape hatch, had there been a reason for it. But the combination of a booster which could potentially have a fairly high explosive yield, and (tentative inference from reading between the lines) the fact that the escape system was an add-on rather than something designed in from the start, made it impractical. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net Back to top   Ads Advertising Sponsor Henry Spencer Guest Posted: Sat May 05, 2007 9:32 am    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn In article <1178214672.376599.232330@n76g2000hsh.googlegroups.com>, John <pelchat@charter.net> wrote: Quote: One thing that I remember reading was that in the early days of Gemini design, some people hated the experiences they were having with Mercury's automatic failure detection systems that would have fired the escape tower. When Titan presented them with a less severe failure mode, they chose seats because the actuation of the seats would be controlled soley by the occupants of the seats. Except, those are actually two independent issues. There's nothing about an escape tower that requires that its operation be automated. Indeed, Apollo started with an entirely-manual escape tower, and reluctantly added a *little bit* of automation, late in development, when it became clear that there were a couple of failure cases where disaster could strike very quickly. And it's conceivable to have automated ejection seats -- indeed, there is some small element of this in sequenced-ejection systems where the vehicle commander firing his seat fires all the others too. Mercury's automated escape system definitely was a can of worms that people had no desire to repeat. But that wasn't an argument for seats or against towers. The real motive for the seats seems to have been a combination of (a) it was convenient, for Gemini's admitted plans like land touchdown, to have escape available for landing as well as takeoff, and (b) for some of the *un*admitted plans, like lunar Gemini missions, there was a strong desire to make the spacecraft as light as possible, and the seats weighed less than a tower (even after discounting the tower for the fact that it would be shed during ascent). -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net Back to top   Ads Advertising Sponsor Henry Spencer Guest Posted: Sat May 05, 2007 9:32 am    Post subject: Re: Dyna-Soar/Atlas-Centaur In article <133m1v4jbt9br70@corp.supernews.com>, Pat Flannery <flanner@daktel.com> wrote: Quote: No, the original four-engine Centaur concept used pressure-fed engines Turbopump or gas pressurization? "Pressure-fed" means no pumps. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net Back to top   Ads Advertising Sponsor Guest Posted: Sat May 05, 2007 2:48 pm    Post subject: Re: Dyna-Soar/Atlas-Centaur On Sat, 21 Apr 2007 20:39:07 -0500, Pat Flannery <flanner@daktel.com> wrote: Quote: Dyna-Soar on a Atlas-Centaur: http://renax.club.fr/sharkit/altlas-centaur/altlas-centaur.htm Krafft Ehricke would've approved: http://www.geocities.com/atlas_missile/other_missions.htm Pat To accommodate the Model 814-1047-1 and its updated replacement, the Model 814-1050-1, thicker skin gages would provide the necessary booster fuselage stiffness, while the Atlas's ICBM half-stage feature was totally eliminated. Atlas fuel tank capacity and helium pressures were increased, thus generating increased power to 172,000 pounds of thrust. -- Does this section from the article Pat quoted mean that the two boosters would NOT be staged after about 130 seconds? Back to top   Ads Advertising Sponsor Pat Flannery Guest Posted: Mon May 07, 2007 5:56 am    Post subject: Re: Dyna-Soar/Atlas-Centaur Henry Spencer wrote: Quote: Turbopump or gas pressurization? "Pressure-fed" means no pumps. Okay... I was tired when I typed that. ;-) That's not going to help the mass fraction of the stage at all, particularly give the low density of the LH2, and resulting large stage tankage size, to be pressurized. On the drawing of the Atlas/proto-Centaur* there are cylindrical housings above the engine bells of the motors that look too large to be simple combustion chambers, so I assumed that was where turbopumps were housed: http://www.geocities.com/atlas_missile/images/Atlas_Orbital_System.gif * If it is a proto-Centaur; the page doesn't say anything about the details of the upper stage, and I haven't had any luck tracking its details down yet. Pat Back to top   Ads Advertising Sponsor Pat Flannery Guest Posted: Mon May 07, 2007 9:19 am    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn Henry Spencer wrote: Quote: No, I'm afraid not. Mercury could have been designed with such an escape hatch, had there been a reason for it. But the combination of a booster which could potentially have a fairly high explosive yield, and (tentative inference from reading between the lines) the fact that the escape system was an add-on rather than something designed in from the start, made it impractical. Don't forget the weight factor; on Mercury every ounce counted due to the limited lifting capability of the Atlas. I'm still fond of the idea of the dual-use LES/retro concept - to some extent Gemini used that idea if it had to separate while above the majority of the atmosphere. (I'll have to check this, but I think Vostok may have had a way of separating from its upper stage via firing its liquid-fueled retro in the same way...lower than that, and you counted on the ejection seat, which had a walloping big pair of RATO bottles on it to blow you free from the fireball. Looking at the size of them, they appear to be able to get the seat going at around a couple of hundred MPH sideways by the end of their burn). I always got a kick out of the fact that Mercury and Sputnik 3 weighed almost exactly the same. If the Soviets had thought things through and went for a minimalist capsule rather than the dual-use Vostok/Zenit design, they might have been able to have a man in orbit in the 1958-59 time-frame. That would have _really_ shook us up. IIRC, the Mercuries did have a parachute carried for the astronaut to don in case the main chute failed, although the general consensus was that you weren't going to have the time to put it on and crawl out the hatch before the capsule hit the water. Pat Back to top   Ads Advertising Sponsor Pat Flannery Guest Posted: Mon May 07, 2007 9:48 am    Post subject: Re: Dyna-Soar/Atlas-Centaur BigRIJoe@yahoo.com wrote: Quote: Does this section from the article Pat quoted mean that the two boosters would NOT be staged after about 130 seconds? We've gone into this before; it's an interesting concept, because you could save a lot of weight on the Atlas by eliminating the equipment required for staging the outer two engines. If your going to do this, you might want to replace the central motor with the same type as the outer ones, as you don't need to use it to get into orbit, but just want maximum thrust at liftoff to carry a second stage to fairly high altitude and velocity. You could put a very big second stage on it by having that liftoff thrust. ....._big_ tanked Centaur, probably with four RL10s. The first stage would work in a very similar way to the Shuttle's SRBs, or the Saturn V first stage. Considering that out-of-control Atlas' showed pretty high structural strength under aerodynamic loads, maybe you could pull it off by increasing the gage of the skin of the Atlas and upping the pressurization value while on the pad to support the weight of the big new upper stage. Pat Back to top   Ads Advertising Sponsor Henry Spencer Guest Posted: Thu May 10, 2007 6:50 am    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn In article <133tdotcbcu1qff@corp.supernews.com>, Pat Flannery <flanner@daktel.com> wrote: Quote: If the Soviets had thought things through and went for a minimalist capsule rather than the dual-use Vostok/Zenit design, they might have been able to have a man in orbit in the 1958-59 time-frame. That would have _really_ shook us up. Despite the Russians' Cold War reputation as evil scum careless of human life, they were in fact quite cautious with their cosmonauts. The US took chances that the Russians would never have dreamed of, e.g. manning the third Saturn V after multiple serious problems on the second. (Korolev's rule was no manned flights until there were two clean, safe, successful unmanned tests in a row.) This was part and parcel of something that the West definitely did not understand very well until recently: even in its heyday, the Russian space program never had the sort of sky-high priority that the US space program had then. Korolev & co. rarely had the sort of firm political backing needed to justify taking big risks, even for big gains. They had enough trouble debugging their hardware as it was, and they were pretty much forced to proceed cautiously and systematically. Quote: IIRC, the Mercuries did have a parachute carried for the astronaut to don in case the main chute failed... Don't think I've ever seen any reference to that (and I'm skeptical that there'd be any place to put it -- Mercury was *small*). Mercury did have a reserve chute, yes, but it was a full backup for the main chute. (Gemini didn't need a reserve chute because, in principle, the crew could always eject. And Apollo got its chute redundancy in a different way, using three main chutes and being able to survive one of them failing.) -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net Back to top   Ads Advertising Sponsor Dave Michelson Guest Posted: Thu May 10, 2007 9:58 am    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn Henry Spencer wrote: Quote: IIRC, the Mercuries did have a parachute carried for the astronaut to don in case the main chute failed... Don't think I've ever seen any reference to that (and I'm skeptical that there'd be any place to put it -- Mercury was *small*). Mercury did have a reserve chute, yes, but it was a full backup for the main chute. Among other places, it's mentioned in "This New Ocean". Shepard's personal parachute was somewhat in the way when he used the hand controller. I seem to recall that Curt Newport found Grissom's personal parachute, or portions of it, in Liberty Bell 7. I don't believe that any of the orbital flights carried one, though. -- Dave Michelson davem@ece.ubc.ca Back to top   Ads Advertising Sponsor Pat Flannery Guest Posted: Thu May 10, 2007 3:28 pm    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn Henry Spencer wrote: Quote: Despite the Russians' Cold War reputation as evil scum careless of human life, they were in fact quite cautious with their cosmonauts. Except for the Voskhod flights, with no escape systems. Quote: The US took chances that the Russians would never have dreamed of, e.g. manning the third Saturn V after multiple serious problems on the second. (Korolev's rule was no manned flights until there were two clean, safe, successful unmanned tests in a row.) The manned first Shuttle flight is the one that still shakes me up. _Manned_ all-up testing?! Quote: This was part and parcel of something that the West definitely did not understand very well until recently: even in its heyday, the Russian space program never had the sort of sky-high priority that the US space program had then. Korolev & co. rarely had the sort of firm political backing needed to justify taking big risks, even for big gains. They had enough trouble debugging their hardware as it was, and they were pretty much forced to proceed cautiously and systematically. I wish we could figure out a way to put a dollar value on their whole space program, because I think they spent only about 1/2 as much as we did. Quote: IIRC, the Mercuries did have a parachute carried for the astronaut to don in case the main chute failed... Don't think I've ever seen any reference to that (and I'm skeptical that there'd be any place to put it -- Mercury was *small*). They found Grissom's personal chute inside Liberty Bell 7 when they recovered it: http://en.wikipedia.org/wiki/Mercury-Redstone_4 "Some of the interior aluminum panels showed deterioration but some fabric pieces, including Grissom's personal parachute, were perfectly intact. " At least Shepard's also carried a personal chute: http://history.nasa.gov/SP-4201/ch11-4.htm "He encountered one small problem while using his hand controller: when he moved his hand to yaw, the wrist seal bearing of his suit bumped into his personal parachute. To make the proper displacement, he had to push hard.^" "Later, during postlaunch debriefings, Shepard stated that the decision to carry or eliminate the personal parachute on subsequent flights should be left for the prime pilot. An unidentified astronaut at the debriefing (probably Schirra) exclaimed, "Please!" " So apparently it sits near the hand controller to your right side. I assume you were supposed to clip it to the front of your suit like a skydiver's reserve chute before you climbed out the hatch. Pat Back to top   Ads Advertising Sponsor Pat Flannery Guest Posted: Thu May 10, 2007 3:31 pm    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn Dave Michelson wrote: Quote: I don't believe that any of the orbital flights carried one, though. It was probably cramped enough in there without sticking a chute in; I wonder how long it took to put it on and crawl out the hatch? Pat Back to top   Ads Advertising Sponsor alain245@sympatico.ca Guest Posted: Fri May 11, 2007 4:07 am    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn On May 9, 10:50 pm, h...@spsystems.net (Henry Spencer) wrote: Quote: And Apollo got its chute redundancy in a different way, using three main chutes and being able to survive one of them failing.) I don't think I like that kind of redundancy. At our skydiving club, there once were two guys who opened their chutes too close to one another. The chutes got tangled together. Fortunetly their reserve chutes worked fine. Alain Fournier Back to top   Ads Advertising Sponsor Henry Spencer Guest Posted: Fri May 11, 2007 7:38 am    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn In article <13460gc9e4vf110@corp.supernews.com>, Pat Flannery <flanner@daktel.com> wrote: Quote: Despite the Russians' Cold War reputation as evil scum careless of human life, they were in fact quite cautious with their cosmonauts. Except for the Voskhod flights, with no escape systems. I'd say they get partial points for that one, because the guy who proposed doing it that way already knew that he was going to be the flight engineer on Voskhod 1...! There were serious suggestions that Apollo did not need an escape system, because it was going to be flying on a purpose-built launcher rather than a converted artillery rocket. It's interesting to consider whether even Mercury would have had one, had Atlas's record not been so bad. Quote: understand very well until recently: even in its heyday, the Russian space program never had the sort of sky-high priority that the US space program had then... I wish we could figure out a way to put a dollar value on their whole space program, because I think they spent only about 1/2 as much as we did. There was an interesting suggestion, at the time, that the fairest way to compare funding was to use the black-market exchange rate. Which gave the Russian manned space program about the same level of total funding as the Smithsonian... an order of magnitude less than the US program. (Granted, this does not count work done to its benefit that didn't show up in its budget... but then, there was no shortage of that in the US either.) -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net Back to top   Ads Advertising Sponsor Henry Spencer Guest Posted: Fri May 11, 2007 7:40 am    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn In article <1178842038.894743.17570@o5g2000hsb.googlegroups.com>, alain245@sympatico.ca <alain245@sympatico.ca> wrote: Quote: And Apollo got its chute redundancy in a different way, using three main chutes and being able to survive one of them failing.) I don't think I like that kind of redundancy. At our skydiving club, there once were two guys who opened their chutes too close to one another. The chutes got tangled together... It's not *quite* the same situation, since the Apollo chutes were fired out (in different directions) by mortars rather than being left to open any way they felt like it. But I would agree that it's a concern. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net Back to top   Ads Advertising Sponsor Fred J. McCall Guest Posted: Fri May 11, 2007 1:46 pm    Post subject: Re: How to leave Dyna-Soar (or MOL) during an Abort WAS: Dyn henry@spsystems.net (Henry Spencer) wrote: :In article <13460gc9e4vf110@corp.supernews.com>, :Pat Flannery <flanner@daktel.com> wrote: :> :>I wish we could figure out a way to put a dollar value on their whole :>space program, because I think they spent only about 1/2 as much as we did. : :There was an interesting suggestion, at the time, that the fairest way to :compare funding was to use the black-market exchange rate. Which gave the :Russian manned space program about the same level of total funding as the :Smithsonian... an order of magnitude less than the US program. (Granted, :this does not count work done to its benefit that didn't show up in its :budget... but then, there was no shortage of that in the US either.) That hardly seems like a reasonable way to measure comparative cost, either. It essentially says that if my currency is worthless internationally then nothing I do internally (where the currency works) costs anything. That strikes me as simply a preposterous notion, given that there are opportunity costs to pursuing the program regardless of whether my internal currency is waste paper or not. One is left wondering what the Soviet military effort would look like using the same 'fair' criteria for measuring it. Pretty small, I would bet... -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. 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