That diameter came from 4.15m being the largest rail-transportable diameter possible when the UR-500 was built. Limiting the diameters of all of its payloads. As you said, flying the pieces over for final assembly at the launch site is possible, it simply comes with increased difficulty.
That diameter came from 4.15m being the largest rail-transportable diameter possible when the UR-500 was built. Limiting the diameters of all of its payloads. As you said, flying the pieces over for final assembly at the launch site is possible, it simply comes with increased difficulty.
To be fair, there might be a different constraint from other directions. the 3.5m was specifically from the factory in the Ukraine.
Actually. Energia Booster/Zenit 1st stages were 3.92m in diameter, which, IIRC, allowed them to be transported to the Plesetsk Launch Site in Russia - OTL, the launch facilities for Zenit were never completed there, only at Baikonur Cosmodrone.
3.9. Yes, of course. That's what my own blasted post said. I thought 'I should go back and double check that number. No, I'm sure it's 3.5.' Gah. Idiot.
A thought. Once Part 1 of Eyes Turned Skywards is finished. Do you have any intent to place it in the Finished Timelines and Scenarios Section? Or are you planning on putting it all there once the entire TL is completed?
Over 28,000 views now. Almost at the 30,000 mark.
Over 28,000 views now. Almost at the 30,000 mark.
Yes, we do. The major thing is catching errors and a few minor retcons, so any help trawling through the thread looking for things that might need mods would be appreciated (feel free to send any of those by PM).
Speaking of modifications and retcons, after thinking about it, it occurred to me that the automated systems of the Aardvark avionics are likely also largely present in the Block III avionics due to the commonality between their SM systems (radar, comms, computers). Thus, converting the Block III+ for a mostly-automated approach and docking is mostly a human factors issue as opposed to a technical one. Likely they'd add a camera relay from the front of MM to the pilot's positions which would let the pilot have override authority if the automated system fails during a docking. A spotting window from the front of the MM could allow another crew member to provide guidance in the event of a failure of both systems. It's not a great system in that case, but with the computer not fully working and the camera relay out...that's an abort by mission rules, I suspect, even if they had direct visuals from the capsule. Thus, the spotter at the MM window in that case would mostly be helping the pilot get safely clear of proximity of the station.
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Has any manned program OTL ever considered a main mission profile use of the Abort system so as not to waste that considerable launch mass if not needed for the emergency function?
Here for instance the Block III+ Apollo escape tower masses 3.5 tonnes, or over a seventh the total stack mass of the system, rather dwarfing the propellent of the SM. Yet the only use we get out of it is to whisk the CM away (at some very high acceleration) should an abort during early launch become necessary. I understand that the earlier one disposes of mass during a launch, the less harm it does to the on-orbit delivered mass. And that an escape tower by American design anyway would be a solid fuel engine that has rather low ISP and can't be throttled or shut down, so the lower propellent mass of the storable liquid propellents of the SM represents a comparable delta-V.
It seems that the TKS tower is retained on a routine mission right until Earth return, so I guess they use it during part of the deorbit. (Or conceivably it is routinely discarded at that point, once the orbital maneuvering engines are doing their final burn smoothly, and was only kept around in case they'd fail at that point).
I guess they would decisively dispose of the utility module by deorbiting it too then separating the entry capsule and fining up its entry profile so as to enter well away from the rest, which burns up and is thus prevented from becoming space junk. It seems they could save some propellent mass and use it for payload by using the escape engine to start the deorbit of the whole ship; the extra mass would ballast the thrust and keep it from subjecting the return capsule and cosmonauts to the hard emergency acceleration it is designed to give for its primary function. Thus they save the emergency reserve capability until the last possible moment, it's always available as a fallback in any contingency and they get value out of it to compensate somewhat for the (necessary!) penalty of covering an emergency they devoutly (in a Marxist-Leninist dialectical materialist way of course! After placating the leshy-gremlins!) hope never happens.
Clearly Apollo III+ can't do that because the dang tower is in the way on orbit; they have to pull out of the stack, turn and dock with the MM much as Lunar Block II had to do with the LM. So they can't retain it all the way to return, but they could include a routine firing on the way up, either supplementary thrust once the final orbital launch stage starts firing reliably (best to use it when the mass is maximal I'd think) or alternatively as a planned final injection stage (higher acceleration and a bit risky if it is the escape tower that somehow fails, and less efficient in delta-V, but of course if the final velocity change was necessary to achieve stable orbit the CM alone should be able to manage an abort reentry if the thing misfires.)
This ought to enhance the mass to orbit on a smooth mission somewhat, and get some value out of what we otherwise (in the God-fearing USA, with straight Judeo-Christian piety) pray is so much useless mass.
I'm following three decent alt-space timelines lately and I forget if the escape system has already been used once by Americans in this timeline, or if that's just in "Sputniks." After the OTL Shuttle disasters I'd never suggest there shouldn't be some sort of escape system, but I do wonder why OTL no one ever actually implemented using them in a routine successful mission like this, since they ain't cheap in launch mass terms.
Here for instance the Block III+ Apollo escape tower masses 3.5 tonnes, or over a seventh the total stack mass of the system, rather dwarfing the propellent of the SM. Yet the only use we get out of it is to whisk the CM away (at some very high acceleration) should an abort during early launch become necessary. I understand that the earlier one disposes of mass during a launch, the less harm it does to the on-orbit delivered mass. And that an escape tower by American design anyway would be a solid fuel engine that has rather low ISP and can't be throttled or shut down, so the lower propellent mass of the storable liquid propellents of the SM represents a comparable delta-V.
It seems that the TKS tower is retained on a routine mission right until Earth return, so I guess they use it during part of the deorbit. (Or conceivably it is routinely discarded at that point, once the orbital maneuvering engines are doing their final burn smoothly, and was only kept around in case they'd fail at that point).
I guess they would decisively dispose of the utility module by deorbiting it too then separating the entry capsule and fining up its entry profile so as to enter well away from the rest, which burns up and is thus prevented from becoming space junk. It seems they could save some propellent mass and use it for payload by using the escape engine to start the deorbit of the whole ship; the extra mass would ballast the thrust and keep it from subjecting the return capsule and cosmonauts to the hard emergency acceleration it is designed to give for its primary function. Thus they save the emergency reserve capability until the last possible moment, it's always available as a fallback in any contingency and they get value out of it to compensate somewhat for the (necessary!) penalty of covering an emergency they devoutly (in a Marxist-Leninist dialectical materialist way of course! After placating the leshy-gremlins!) hope never happens.
Clearly Apollo III+ can't do that because the dang tower is in the way on orbit; they have to pull out of the stack, turn and dock with the MM much as Lunar Block II had to do with the LM. So they can't retain it all the way to return, but they could include a routine firing on the way up, either supplementary thrust once the final orbital launch stage starts firing reliably (best to use it when the mass is maximal I'd think) or alternatively as a planned final injection stage (higher acceleration and a bit risky if it is the escape tower that somehow fails, and less efficient in delta-V, but of course if the final velocity change was necessary to achieve stable orbit the CM alone should be able to manage an abort reentry if the thing misfires.)
This ought to enhance the mass to orbit on a smooth mission somewhat, and get some value out of what we otherwise (in the God-fearing USA, with straight Judeo-Christian piety) pray is so much useless mass.
I'm following three decent alt-space timelines lately and I forget if the escape system has already been used once by Americans in this timeline, or if that's just in "Sputniks." After the OTL Shuttle disasters I'd never suggest there shouldn't be some sort of escape system, but I do wonder why OTL no one ever actually implemented using them in a routine successful mission like this, since they ain't cheap in launch mass terms.
Don't forget that the LES is designed to pull away the capsule from a malfunctioning LV at very high G-Forces - up to 17G IIRC. This means it exerts a significant strain on the stack if used in the manner you propose, and may force the capsule, SM, and payload fairing to be strengthened according - all of which impose a mass penalty that is almost certain to wipe out the payload gains and may even reduce total payload possible to a given orbit.
All of which means the odds of it happening are effectively 0.
All of which means the odds of it happening are effectively 0.
Well, if CM masses 5 tonnes, to pull it at 17 G's requires 85 tonnes of thrust (850 kilonewtons). Just guessing that half a ton of the escape tower is structural and the rest propellant, that's another 10 percent at burnout, call it 920 kiloNewtons. If these guesstimates of mine of the ratio of propellant to structure are correct, then at firing it's 920 KN hauling 8.5 tonnes which means about 11.2 G's initially, 108 m/sec^2. Adding in the whole Apollo III+ stack 20.3 tonnes mass to haul the initial acceleration of the stack is 4.62 Gs which I believe is more than the peak design push from below, the big difference is that the joints that I suppose are designed to simply break (or the pulling stress triggers reliable explosive bolts) in the original design are now bearing 3/4 the force of 690 KN, in tension instead of compression. But that's not a lot more than the structure had to bear in compression being pushed from below anyway, and materials that are strong enough in compression tend to be more than strong enough in tension, by and large.
And if 4.6 G's is pushing it (and it gets harder as the 3 tons of propellent burn out) well, that's why I suggested firing shortly after the final stage burns out.
I see that actually the escape system is only there for first stage burnout, not to be used even during second stage burn, so actually the total mass I'm proposing to haul with it includes the fully fueled second stage too, which means the incremental acceleration it provides this whole stack is pretty low, and brief. Very little of the 920 KN tension gets absorbed by accelerating the upper stack masses, true, essentially all of it has to pass down some sort of tension-bearing members through the orbital stack to the top of the second stage. The second stage gets relieved of mass essentially but should be structurally fine, it's the orbital stack that has this extra strain which however relieves (and more than relieves!) the thrust from below. And mostly then lowers but does not by any means fully offset the compressive strain on the second stage.
Redesigning so the structure works well in both modes is a challenge but I don't think it would add a whole lot of mass, because of the efficiency of materials in handling tension loads. Redesigning so that separation of the CM happens very reliably in an abort but equally reliably does not happen in a routine launch is trickier; also I should worry about how the exhaust backwash affects the stack below.
I usually learn when I ask these outre questions that the way things were done OTL is probably for the best. Still, it seems a glaring waste to me!
And would have seemed like less of one on an OTL (and TTL) Lunar Saturn V stack for a full-on lunar mission. It's the paring down of Apollo Block III that makes the extravagance of launching 3.5 tonnes we hope not to need stand out.
Shevek, I think I've explained this before, but in the 60s the goal was generally to get the job done at all. Using tricks like the ones you describe tend to be more characteristic of systems that have been in use a while, or successors to systems that have long experience histories. In the 60s, neither was true, and most of the towers that have been used were designed then (Mercury, Apollo, Soyuz). TKS I think may have had some planned use for the tower--certainly it was retained all the way to orbit for some purpose, but I'm not precisely sure what.
Of more recent abort systems, I can cite several that do plan to use the abort reserves in some way on a nominal missions, but at least two make use of liquid-fueled systems (which are simply more versatile, at the cost of being a bit more complex). CST-100 plans to use the same propellant tanks for orbital maneuvering and abort, simply using two different sets of thrusters--one very high-power, the other much lower. In an abort, the big thrusters use the fuel to pull the capsule to safety, then landing in the ocean on parachutes. Dragon pulls a similar trick, with two thruster sets--Draco and SuperDraco. However, they plan to do things a little differently--instead of simply using maneuvering fuel in the abort, they plan on adding more fuel, and use the high-power engines for powered terminal descent and landing. I know SNC uses a hybrid abort motor, but I'm not sure if they have plans to use it in a nominal flight for other things--a hybrid at least has some of the ability of a liquid to be used in several shorter burns instead of one longer one. In that sense, Orion's old-style solid-powered tower-based abort system is a bit of a throwback, and it's one of the things about the design where I think Dragon or CST-100 is superior.
Simply put, many modern systems do have at least some plan for using the abort system in a nominal flight, but it generally needs a liquid-fuel abort system and more experience than was available. However, NASA is not really taking advantage of that on the Block III due to the funding situation--the extra few hundred kg that could be obtained by redesigning the abort system or finding another use for it on a nominal flight isn't worth the time delay. As a similar incremental upgrade, Block III+ inherits that same system. In order to find a better use for it, you'd really want a pusher liquid-fueled abort system, and that'd mean an entire new SM and lots of development work.
Of more recent abort systems, I can cite several that do plan to use the abort reserves in some way on a nominal missions, but at least two make use of liquid-fueled systems (which are simply more versatile, at the cost of being a bit more complex). CST-100 plans to use the same propellant tanks for orbital maneuvering and abort, simply using two different sets of thrusters--one very high-power, the other much lower. In an abort, the big thrusters use the fuel to pull the capsule to safety, then landing in the ocean on parachutes. Dragon pulls a similar trick, with two thruster sets--Draco and SuperDraco. However, they plan to do things a little differently--instead of simply using maneuvering fuel in the abort, they plan on adding more fuel, and use the high-power engines for powered terminal descent and landing. I know SNC uses a hybrid abort motor, but I'm not sure if they have plans to use it in a nominal flight for other things--a hybrid at least has some of the ability of a liquid to be used in several shorter burns instead of one longer one. In that sense, Orion's old-style solid-powered tower-based abort system is a bit of a throwback, and it's one of the things about the design where I think Dragon or CST-100 is superior.
Simply put, many modern systems do have at least some plan for using the abort system in a nominal flight, but it generally needs a liquid-fuel abort system and more experience than was available. However, NASA is not really taking advantage of that on the Block III due to the funding situation--the extra few hundred kg that could be obtained by redesigning the abort system or finding another use for it on a nominal flight isn't worth the time delay. As a similar incremental upgrade, Block III+ inherits that same system. In order to find a better use for it, you'd really want a pusher liquid-fueled abort system, and that'd mean an entire new SM and lots of development work.
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no, in fact the TKS VA jettison it's escape tower during launch, (that the long cylinder on top of capsule)
because design of TKS spacecraft, the retrorocket and it's RCS (called BSO module) are direct behind the escape tower before parachute compartment.
on fotos you see the BSO module as short cylinder with 4 small rocket engine, on top of cone contain the parachute
All right, I'm calling "Uncle!" on this notion of not wasting the escape tower.
I was thinking about arguing for replacing the tower with beefed-up service module engines, as it seems that with solid fuel ISPs in the ballpark of 250 or so (I could not get figures for the ISP of the OTL Apollo escape tower main rocket, nor even a breakdown of how much of the overall mass of the tower system was propellent--I've been guessing between 1.5 and 2 tonnes--anyway the thrust varies with atmospheric conditions by a factor of 25 percent) versus something over 300 for the storable propellent of the SM, we could get the same delta-V with 2/3 the propellent mass. However I can only guess how massive an engine would be needed to match the thrust of the solid rocket; the specified burn time for the Apollo system as deployed OTL was just 4 seconds. (I haven't been able to square Dathi's mentioned 17 Gs, presumably at burnout with maximum thrust, with the mass of the CM, which in Block II was 5.5 tonnes, either). Say this for solid engines, the thrust-to-mass ratios are impressive! A liquid-fuel engine capable of delivering 890 kiloNewtons of thrust would be somewhere between 500 kg and several tonnes mass, considerably bigger than the OTL Block II SM engine, let alone the scaled-down Block III. I gave up when I couldn't think of an elegant way to mount an "auxiliary" SM engine whose thrust dwarfs the standard engine, and burns through a full load of Block III SM propellant and then some in just a few seconds, nor how to jettison the thing when no longer needed.
And the problem of assuring clean escape for abort versus assuring the thing stays attached while firing for boost assist is a bugger too. I'm thinking, clamps of some kind that are loose until first stage burnout, but that's more weight. (I don't think the mass of structural reinforcements to take the thrust is a problem as such, but making it swing in smoothly like that may be).
I suppose, since the escape tower is discarded after first stage burnout, I should simply think of the 3.5 tonne mass as part of the first stage unfueled structure; then it doesn't look so bad.
And unless I'm misreading different definitions of what is and is not part of an "escape tower," the way NASA defined it in the 60s OTL anyway the Block I/II versions massed 4.2 tonnes, so the Block III/III+ version at 3.5 tonnes has been pared down anyway, by 700 kilograms. Presumably it is more efficient, either using a higher-performance solid propellant or saving a lot of mass on the non-propellant structure, since the CM itself is not notably lighter. (Or is it?)
I was thinking about arguing for replacing the tower with beefed-up service module engines, as it seems that with solid fuel ISPs in the ballpark of 250 or so (I could not get figures for the ISP of the OTL Apollo escape tower main rocket, nor even a breakdown of how much of the overall mass of the tower system was propellent--I've been guessing between 1.5 and 2 tonnes--anyway the thrust varies with atmospheric conditions by a factor of 25 percent) versus something over 300 for the storable propellent of the SM, we could get the same delta-V with 2/3 the propellent mass. However I can only guess how massive an engine would be needed to match the thrust of the solid rocket; the specified burn time for the Apollo system as deployed OTL was just 4 seconds. (I haven't been able to square Dathi's mentioned 17 Gs, presumably at burnout with maximum thrust, with the mass of the CM, which in Block II was 5.5 tonnes, either). Say this for solid engines, the thrust-to-mass ratios are impressive! A liquid-fuel engine capable of delivering 890 kiloNewtons of thrust would be somewhere between 500 kg and several tonnes mass, considerably bigger than the OTL Block II SM engine, let alone the scaled-down Block III. I gave up when I couldn't think of an elegant way to mount an "auxiliary" SM engine whose thrust dwarfs the standard engine, and burns through a full load of Block III SM propellant and then some in just a few seconds, nor how to jettison the thing when no longer needed.
And the problem of assuring clean escape for abort versus assuring the thing stays attached while firing for boost assist is a bugger too. I'm thinking, clamps of some kind that are loose until first stage burnout, but that's more weight. (I don't think the mass of structural reinforcements to take the thrust is a problem as such, but making it swing in smoothly like that may be).
I suppose, since the escape tower is discarded after first stage burnout, I should simply think of the 3.5 tonne mass as part of the first stage unfueled structure; then it doesn't look so bad.
And unless I'm misreading different definitions of what is and is not part of an "escape tower," the way NASA defined it in the 60s OTL anyway the Block I/II versions massed 4.2 tonnes, so the Block III/III+ version at 3.5 tonnes has been pared down anyway, by 700 kilograms. Presumably it is more efficient, either using a higher-performance solid propellant or saving a lot of mass on the non-propellant structure, since the CM itself is not notably lighter. (Or is it?)
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Oh. I couldn't see your post when I was writing the last one; I'll delete the question there about the TKS escape system forthwith! Thanks!
About the discussion on Transport and diameter limitation of Soviets rockets
Most Soviet rocket are transported by rail what limit the diameter on 4.15 mø
exception are N1 and Energia
the N1 was assembled near launchpad
this facility was reused for Energia assembly in 1980s
http://photofind.com/wp-content/main/2010_05/Buran-9.jpg
transport of Energia rocket, the Soviet union went new way, they used aircraft
Most Soviet rocket are transported by rail what limit the diameter on 4.15 mø
exception are N1 and Energia
the N1 was assembled near launchpad
this facility was reused for Energia assembly in 1980s
http://photofind.com/wp-content/main/2010_05/Buran-9.jpg
transport of Energia rocket, the Soviet union went new way, they used aircraft
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It's not so bad that you're interested in the notion of using the abort system for some other role during a nominal mission, instead of essentially wasting it. It's just that the system (not just the abort system but the entire vehicle) really needs to have been designed to do that from the start.
Indeed. Step one is to fit more than one engine instead of one massive one, but it's still a lot of mass. The 8 SuperDracos for SpaceX's Dragon probably mass about 800 kg (8 engines, each with a rated 67 kN, and a T/W of maybe 40). You're accepting a lot of mass penalty, so in the end it may be close to a wash in useful payload once you consider the extra fuel you need for any given orbital manuever. The main advantage comes in a reusable capsule like Dragon, where you can then bring the engines home for the next flight (hopefully unfired!) or use them for a precision-guided landing on land (though this requires serious throttling). I'm amazed at all the hardware SpaceX is planning to cram into the Dragon service areas what with the abort system on top of the existing Draco manuevring systems--consider that each SuperDraco has the same thrust as the Apollo CSM (though it has a much smaller nozzle due to optimization for sea-level use). I've given some thought to interesting other uses for the SuperDraco once Falcon Heavy comes online OTL, but...that's not really relevant here.
Slightly after, actually. I probably should have said after 2nd stage ingnition--once that's done, the major catastrohpic failure events are behind you.I suppose, since the escape tower is discarded after first stage burnout, I should simply think of the 3.5 tonne mass as part of the first stage unfueled structure; then it doesn't look so bad.
Mostly it's a reduction in impulse required to get to a safe distance from the Saturn 1C if it lets go compared to the rather larger danger zone from a Saturn V. If they were to ever put a manned capsule on the Saturn H02 or H03 (or anything other than the M02, really), they'd need to likely give the tower another look.
Hmm. Thank you for shedding light on that, Michel. I'm leaning slightly towards air-transported 6m stages, though this means a fair amount of flights. There were two VM-Ts OTL, so that may be sufficient. A 6m core would make the Herakles and Atlas versions roughly 17m when assembled, thus they'd be about the same width as the N1, allowing them to use the same assembly facility there as Energia/buran did OTL. This core diameter also has implications for the MOK core module--it can use the 6m diameter that was being studied for the OTL MOK/OS-1 design, which is convenient for me (I like being able to crib from OTL, it makes me feel less like I'm going out on a limb and picking numbers out of thin air).
Consider that Boeing is running its 787 manufacturing hauling bits around the world with only 4 Dreamlifters, I can't imagine that 2 transports would have problems shuttling rocket parts.
In any case, converting a couple more transports should be trivial if they were needed.
I was going by information online about what the practice was for Apollo OTL; they said it was ejected at first stage burnout or shortly after.
And that the escape mode for a second stage failure abort was to fire the SM, which influenced my thinking about fixing up the SM to be able to handle the escape at any stage; you need a bit more propellant and much more powerful engines to match the impulse the escape tower offered. As you say for the Block III Apollos you figured they wouldn't have to be separated as far to survive an exploding first stage, so we don't have to quite match it. But we do need pretty much all the thrust unless it is acceptable in the worst case to accelerate more slowly, which I would never assume without seeing the math all worked out.
I guess that between the second stage having a lot less propellant in it and a possible second stage explosion happening in much thinner atmosphere, the radius of critical damage from blast and debris would be lower.
Of course, your Block III SM engine has been downsized to better suit its function as an orbital maneuvering engine, with no nonsense about being a lunar ascent engine, so it would be less adequate, so I guess you might want to keep the tower around until second stage burnout, or anyway until the propellent mass has been depleted a lot (and the rocket has risen into even thinner air).
But the longer we keep it around, the more impact it has on mass to orbit.
Goodyear submitted a proposal to NASA in the late 1950s for bundling together two of their largest blimp hulls (which were the biggest blimps ever to fly yet) for an aerostatic transport system. I despaired of finding information on it on the Internet; I read about it in the book Skyships: A History of the Airship in the United States Navy, by William Althoff (Pacifica Press, 1990). I scanned the image below from page 252.
To give an idea of scale, a ZPG-3W was (all units in American customary, I can't take the time to convert every one of them to metric!)
1,516,300 cubic feet gas volume
403.4 feet long
designed to cruise at 45 knots (though a -3W, or perhaps a somewhat smaller -2W, holds the unofficial speed record for a blimp or any kind of airship, at 80+ knots).
I don't have useful lift figures in Althoff, but extrapolating from the WWII "M" ships (the biggest blimps ever built until the ZPGs) I figure about 15 tonnes of useful lift was available from each.
Here there are two ganged together, so at least 30 tonnes available. Bearing in mind the Mike ships I am extrapolating from were older tech and included some wartime gear not necessary for this transporter.
NASA did take the proposal somewhat seriously. The main questions about using a purpose-designed LTA hauler of some kind versus making an airplane big enough to carry stages as large as you might want would be, first of all how monstrous a stage might one wish to haul? Would it push the state of the art of big airframes too far for an airplane? Second, NASA was interested in the blimp as a low-vibration, gentle, yet fast (relative to a barge) and pretty direct mode of transport. But if the experience they had later with the "Guppy" planes that hauled upper stages around OTL was good enough, if the vibrations and accelerations of winged airborne transport posed no threat, then I guess planes would tend to win out, provided they can operate from fields near enough to factory and final assembly area at the launch base so that available transports (whether off the shelf or purpose made) can haul them. Airships need some sort of landing field too of course, if only a mast and a big circle cleared for it to weathervane into the wind when grounded, but I think if one contrives to have all the lift necessary available as static lift, that landing zone can be much closer to the factory and vehicle assembly building door. Still, something has to wrangle the stage the last few hundred meters; it may be no hardship to make the same vehicle have to crawl with it a kilometer or two instead to a runway.
Well, anyway I hope someone enjoys the picture. The caption didn't scan well so I will retype it here:
William Althoff said:
You have a good point about the need to retain the tower longer in the burn since the SM engine is not powerful and thus impacts the ability to use it in an abort. As you say, this likely means it needs to stay almost all the way to orbit--luckily, this is already accounted for in the numbers above since I basically designed this to be okay even if the tower had to be carried all the way to LEO.
Nifty image. A few things:
(1) The Vulkan first stage is roughly 43,000 kg dry.
(2) Conveniently, we actually know what the Russians did faced with this problem OTL: first, they looked at a larger version of the An-124, which became the An-225 with addition of H-tail in place of the conventional tail, a lengthened fuselage, and longer wings. Oh, and another pair of engines. When that was taking too long, they looked at the M-4 bomber and said, "That'll do in the meantime." With some slight tail mods and some increased thrust, they produced the VM-T in only 3 years from concept to first flight. Capacity was apparently sufficient for carrying the Vulkan 1st stage, as the VM-T could carry the 82-ton Buran shuttle.
(3) Stages are a bit more durable than you'd think. Launch, after all, is not a particularly gentle or low-vibration condition, and they have to survive that (even with the damping difference made by the fuel, it's still a pretty rocking ride). Almost nothing an aircraft could dish out in transit short of crashing would be worse than LV conditions.
So in short, as OTL it looks better for the Russians to modify versions of existing aircraft (a well-proven technology they have lots of experience with) for what is likely to be a one-off airframe type instead of a massive new program for a cargolifter blimp. They are, after all, building a rocket program, not a cargolift airline. Anything that looks like the latter is mostly driven by the needs of the program, tempered by the logistical and financial realities. A blimp might have some interesting advantages. OTL, that's never been enough for anyone to finish one purely fo the massive airlift role, and with their focus on the ned to move rockets as opposed to nifty tech, the Russians will almost certainly follow what they did OTL.
It's irrelevant to your timeline, with its POD half a decade after the Navy LTA program was shut down. Actually we'd need a timeline with the POD in the 1950s. The Russians have not done much with LTA. I was actually thinking of an American application. I just put it out there in case anyone (this timeline, or ESA, or Sputniks, or anyone else who wants to step into the ring) wanted to move big rocket stages around and was finding that airplanes couldn't handle the job.
I was thinking of someone remembering Goodyear's proposal (or in some 1950s POD timeline, its actual implementation for rockets considered big at that time) and thinking, aha, we need something like this but bigger!
"Blimps" might not cut it. Full disclosure--some years after this 1959 proposal, one of the Navy's ZPG-3Ws crashed off Massachusetts. There's some controversy about just what happened; in the enquiries afterward Goodyear blamed pilot error while the survivors of the crew said the fabric of the upper hull ripped open. The -3Ws were really pushing the state of the art. We could probably do a lot better today, with more modern materials. But with these big ships we might prefer to switch back to a rigid airship design. Coming at it with a clean sheet of paper, something about the size of Hindenburg (or the helium-lifted American rigids Akron or Macon, which were nearly as big) could manage a 50 tonne payload, considering weight savings possible with more modern materials.
Just looking at that Goodyear proposal I see it as quick lash-up Mark I at best; you'd think they'd want to at least fair over the gaps between the noses and sterns of the component blimps; from there it seems straightforward to fill that volume with more helium and lift more. There's some aerodynamic advantage to making a broader hull, if one is anticipating a lot of dynamic lift--indeed by the 1950s the Navy blimp operations routinely took off heavy and sometimes still had some excess weight when landing too. The last time I was thinking about this I was assuming a lot of the lift would be dynamic. So actually, if we could trust this thing not to split its seams in flight, it might have been up to hauling a Vulkan stage, as designed then. Nowadays I feel that if one wants an airplane, make an airplane; if one wants an airship, design it around its static lift capabilities, don't make it rely routinely on dynamic lift. A straight airship has the advantage that it has the same lift at any airspeed including zero.
But yes, it seems that, while there might have been some reasonable concern back in 1959 they couldn't manage it, that airplanes work just fine. Everyone who can think seriously about a space program of their own makes airplanes; all the first-rank potential space program nations have firms or their equivalent that have made some really big ones. With an airplane of course tonnage is not the problem, the problem is the volume of the load. That's not a big problem for the airships, that are so huge already anyway. But while it is a problem for planes, it's a problem that by now has been solved. Evidently no one is too worried about landing the load some miles away instead of right at the gates, and to be sure, an airship big enough to haul a 43 tonne Vulkan stage won't dock right at the gates either.
Hey, I'm trying to remember where I saw the proposal for a flat-bed jet transport. It looked like someone had taken a C-5 or the like and just crimped its fuselage down like a tube of toothpaste. The idea is, just load your awkward bulky cargo right onto the back, out in the breeze. Presumably one puts tarps on it and tightens them down real well with straps, but it's OK that there's drag, the engines have enough thrust to overcome it. This might work especially well for rocket stages, which are streamlined already pretty much; you probably don't even need the tarp!
(Your Evolved Apollo stages seem especially well suited to this approach, with their built-in attachment points and structural reinforcements for parallel first stages--just roll then on so one of those panels faces down, and bolt the thing onto the plane using it).
I still don't remember where I first saw the idea, but here's the patent. It's a Lockheed design, the year was 1983. So assuming that the aero industry and the military aren't massively butterflied by the early '80s (and it seems that on the whole they aren't) the idea is, um, in the air right about "now" in ETS.
It seems like just the thing--a standard cargo plane for a standard rocket stage cargo! With DoD fingerprints all over it--Reagan ought to love it.
Nothing in the patent or the Wikipedia article on it says anything about the weights but the Wiki article does say it looks about the size of an L-1011, which in its earliest version had a take-off weight of 200 tonnes, a landing weight of 167, and structural weight of 102.
So if the length of the "bed" is long enough for the biggest rocket, it ought to handle the mass just fine, even allowing for degraded performance due to poor streamlining.
I was thinking of someone remembering Goodyear's proposal (or in some 1950s POD timeline, its actual implementation for rockets considered big at that time) and thinking, aha, we need something like this but bigger!
"Blimps" might not cut it. Full disclosure--some years after this 1959 proposal, one of the Navy's ZPG-3Ws crashed off Massachusetts. There's some controversy about just what happened; in the enquiries afterward Goodyear blamed pilot error while the survivors of the crew said the fabric of the upper hull ripped open. The -3Ws were really pushing the state of the art. We could probably do a lot better today, with more modern materials. But with these big ships we might prefer to switch back to a rigid airship design. Coming at it with a clean sheet of paper, something about the size of Hindenburg (or the helium-lifted American rigids Akron or Macon, which were nearly as big) could manage a 50 tonne payload, considering weight savings possible with more modern materials.
Just looking at that Goodyear proposal I see it as quick lash-up Mark I at best; you'd think they'd want to at least fair over the gaps between the noses and sterns of the component blimps; from there it seems straightforward to fill that volume with more helium and lift more. There's some aerodynamic advantage to making a broader hull, if one is anticipating a lot of dynamic lift--indeed by the 1950s the Navy blimp operations routinely took off heavy and sometimes still had some excess weight when landing too. The last time I was thinking about this I was assuming a lot of the lift would be dynamic. So actually, if we could trust this thing not to split its seams in flight, it might have been up to hauling a Vulkan stage, as designed then. Nowadays I feel that if one wants an airplane, make an airplane; if one wants an airship, design it around its static lift capabilities, don't make it rely routinely on dynamic lift. A straight airship has the advantage that it has the same lift at any airspeed including zero.
But yes, it seems that, while there might have been some reasonable concern back in 1959 they couldn't manage it, that airplanes work just fine. Everyone who can think seriously about a space program of their own makes airplanes; all the first-rank potential space program nations have firms or their equivalent that have made some really big ones. With an airplane of course tonnage is not the problem, the problem is the volume of the load. That's not a big problem for the airships, that are so huge already anyway. But while it is a problem for planes, it's a problem that by now has been solved. Evidently no one is too worried about landing the load some miles away instead of right at the gates, and to be sure, an airship big enough to haul a 43 tonne Vulkan stage won't dock right at the gates either.
Hey, I'm trying to remember where I saw the proposal for a flat-bed jet transport. It looked like someone had taken a C-5 or the like and just crimped its fuselage down like a tube of toothpaste. The idea is, just load your awkward bulky cargo right onto the back, out in the breeze. Presumably one puts tarps on it and tightens them down real well with straps, but it's OK that there's drag, the engines have enough thrust to overcome it. This might work especially well for rocket stages, which are streamlined already pretty much; you probably don't even need the tarp!
(Your Evolved Apollo stages seem especially well suited to this approach, with their built-in attachment points and structural reinforcements for parallel first stages--just roll then on so one of those panels faces down, and bolt the thing onto the plane using it).
I still don't remember where I first saw the idea, but here's the patent. It's a Lockheed design, the year was 1983. So assuming that the aero industry and the military aren't massively butterflied by the early '80s (and it seems that on the whole they aren't) the idea is, um, in the air right about "now" in ETS.
It seems like just the thing--a standard cargo plane for a standard rocket stage cargo! With DoD fingerprints all over it--Reagan ought to love it.
Nothing in the patent or the Wikipedia article on it says anything about the weights but the Wiki article does say it looks about the size of an L-1011, which in its earliest version had a take-off weight of 200 tonnes, a landing weight of 167, and structural weight of 102.
So if the length of the "bed" is long enough for the biggest rocket, it ought to handle the mass just fine, even allowing for degraded performance due to poor streamlining.