Some ATL US Space Program questions, with pictures.

Ok, so my 30 ish ton OSS, with an identical (Or less) fuel load for the OMS, but no SSME as it doesn't have them, and then the 50-70 tons for the sheathing...
You do have SSME, they're your main ascent engines. They're just not mounted on the OSS. They're still mounted to the stack somewhere which means they're coming out of the mass that reaches orbit. If they're not included in the mass of the OSS, then you need both the 12 tons of engine themselves and a 10-or-so-ton thrust structure to mount them to the vehicle. If they're in the OSS, then that makes the OSS heavier by 12-18 tons.
I really want to include the "Sheathing" thing in my ATL, mainly for coolness factor, something like, "I thought of this" kinda thing.
To be honest, by the time you add it up, I'm not sure what this "sheathing" method gets you over directly using the ET itself. Once you've finished days of EVA to pull the ET out of the sheath, you basically have exactly the same thing: an empty pressurized can with some foam on it and leftover mounts for the SRBs and Shuttle. Why spend an extra 40-60 metric tons duplicating what you could get from an ET workshop? That design has enough problems on its own that its not worth borrowing more trouble with the sheathing idea by adding more dead weight to the stack.
 
Also consider: With the sheathing method, it becomes necessary to carry the ET up to orbit since it's hard to jettison it from inside the can. That actually eats up something like 20-30 tonnes from the orbital payload.

What may be more fruitful to consider is a specialized version of the ET, that uses a different sort of foam and has an external metal skin for better survival in space. Maybe even pre-install things like airlocks, if they don't undermine the function of the tanks as tanks...

fasquardon
 
Also consider: With the sheathing method, it becomes necessary to carry the ET up to orbit since it's hard to jettison it from inside the can. That actually eats up something like 20-30 tonnes from the orbital payload.
The numbers I've seen say that you get MORE payload taking the ET to orbit and using LH2 all the way up.
 
Yea, I was planning to take the ET to orbit, or rather, I put the SSME on the bottom, and changed my ET to a Liquid Fueled Rocket, so it kinda has to goto orbit, as my OSS only has OMS.
 
Yea, I was planning to take the ET to orbit, or rather, I put the SSME on the bottom, and changed my ET to a Liquid Fueled Rocket, so it kinda has to goto orbit, as my OSS only has OMS.

Well, if you are re-designing the ET to be a liquid fueled rocket, you'll need to make big structural changes anyway. So maybe in this ATL, they make new shell for the LH2 and LOX tanks both structurally able to perform as a rocket stage AND able to be a better basis for a wet workshop.

The numbers I've seen say that you get MORE payload taking the ET to orbit and using LH2 all the way up.

Really? Got a reference for that? Because I'd love to see the math for it.

fasquardon
 
Really? Got a reference for that? Because I'd love to see the math for it.

fasquardon
Hmmm....
I've found a couple of links that talk about a mass penalty for taking the ET all the way into orbit - but they assume using the OMS system to circularize the orbit. What I am vaguely remembering from decades ago is a proposal that would use ET fuel (rather than OMS) to circularize orbits. Since the Orbiter (iirc) masses more than the tank does, the extra delta-v of LH2 over hypergolics improved total payload to orbit.

Can I find a link? No, not now at least.
 
I've been doing some work on a rewrite of 'Seeing Further' and decided to go with a near OTL STS shuttle (save for a pair of jet engines in the wing roots for more cross range), and needed an HLV for a Mars mission (nuclear). So I've done some math and design for an SLS lite, by merely sticking the STS engines to the bottom of the external tank and add the payload on top.

wCE2291.png

Shuttle parts are from the NASA 3D model repository.
:p

Now I ask you--why not take the thing on the right, and use it for every launch? If you want to send up cargo, send up cargo. If you want to send up people who of course require at least the option of safe return to Earth, make a space bus of some kind, one that mounted up there on top, in addition to advantages e of pi listed, also can more possibly have some kind of escape system. If you need to retrieve something from orbit--not done all that often OTL--make a reentry shell of some kind to launch empty (or with a bit of cargo to make up the maximum launch weight rattling around inside) and stuff the down mass into that when the cargo is stowed. It shouldn't generally be necessary to have crew accompany the down-mass carrier if the down mass comes from a space station. If it is a question of going out to some defective satellite in an isolated orbit and hauling it down, it might be necessary to provide some crew to do the stevedore work, but this just means that 1) a means of this crew escaping a launch gone bad needs to be provided and 2) more mass for general habitability, and mission related equipment.

So here I'm listing 5 or 6 different types of payload. One is unmanned payload as such. OTL the STS designers promised prospective customers for launch that the Orbiter would provide services for the various payloads that would allow them to simplify construction. Also, the limited G-load aimed at in the design (under 3.5 Gs in all circumstances) would ease it as well, so if we want to meet those promises, we need to design the launcher accordingly--it costs in gravity loss hence a bigger system than if we ignored that G limit and shoved stuff into space with peak Gs around 6-8. (This is one reason the Soviets could launch big payloads in the multi-ton range with the relatively modest R-7 rocket base--that system put pretty high G loads on, as did/does Proton). Anyway in addition to modest G loads STS promised cargo support, and the way I envision an STS variant that would be dramatically more economical would involve the payload package, whatever it is, being placed initially in a very low orbit, so some of our total initial mass has to be devoted to fuel and engines to move the the package up to the desired orbit. This is relatively modest, but I've been thinking an all up rule of thumb is that only about 60 percent of the package can be actual revenue payload, on the terms STS promised anyway. We can kick that up near 100 percent by telling the customers their payloads are their business, all STS promises to do is deliver them to that initial low orbit and they have to make their own way from there. But assume for the moment NASA promises the coddling, then a "cargo" load still involves a vehicle bus massing some 10 tons for every 15 tons of revenue payload carried. This is a vehicle, and it is going to cost.

But hey, if you read the Shuttle Decision book it is clear that NASA required work for all their subdivisions; designing a disposable cargo bus and then tailoring it for each launch keeps Marshall and perhaps JPL or Ames busy!

Then, assuming we have a space station, we have need for the station bus; this is a system to deliver some large number of people. If we are working with 120 tons, we will be delivering a hell of a lot of people to what must be some gigantic space station! The trouble here is that it is irresponsible to design a crewed spacecraft that does not have survivable abort contingencies covering the entire launch. Escape from an exploding stack requires substantial delta-V and in the early stages, requires it to be applied very fast, within a second or so, to get adequate distance separation from the disaster in progress. Then it has to land somehow. If we are looking at 8-12 people, it can be done. Several hundred, and no.

It probably makes a lot more sense to limit the size of a pure human transport bus to something realistic launch escape systems can handle and use any extra capacity (out of a 120 tons it would be a lot) for cargo as usual. Presumably this is all cargo destined for the same space station so that works out well. The crewed ship sits on top, the cargo, to be sacrificed in an emergency situation, is below.

Which tells us how missions typical of STS OTL would be designed. A people bus ship with full abort capability and spartan survival conditions rides ahead of a crew expanded habitably/workshop module. We can design the latter to be a disposable cargo with no provision for return to Earth (except in the form of sending it to destruction in the atmosphere for disposal) or we can integrate the core crew bus into a larger landable craft for reuse. This flexible concept again keeps design teams busy for individual missions.
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Anyway, your cargo launcher version sacrifices the main engines, being attached to a non-returnable tank. My proposal is to do your thing on the right (on a different scale probably, though I'd sure hope to work up to yours, and beyond!) but put the engines in some kind of capsule to allow them to return. I think that an SSME can be contained in a structure all up less than 15 tons, perhaps as little as 12--10 would be pushing it I'd admit. And we can approach solving this problem from several directions. Some sort of Gemini or Apollo type capsule that folds its upper cone side like petals of a flower around the exhaust bell of an SSME would be a compact structure that still could allow the 11 degrees gimbaling of the engines STS required, and we'd just design different size tanks to bolt them on to for different sized missions. More elegant, if perhaps heavier, would be to make some sort of space plane or lifting body for each engine and then they could perhaps fly back to runway or pond landings at the launch site after a once-around orbit.

If this system were implemented, you would have to deduct somewhere between 30 and 60 tons from payload for a 3-engine system, probably closer to 36-45 tons. But the engines would go on being reused.

Or of course if you could return the tank too, with engines attached, the reusability would be greater but probably the payload penalty higher.

In addition to matching the reusability of the OTL Shuttle while allowing delivery of larger payloads, this approach allows tailoring of different size of launch vehicle. Unless the greater economy going with greater payloads raises demand tremendously over OTL, causing the "space rush" Shuttle Decision planners assumed would happen, 120 tons to LEO, even with 40 deducted to leave 80, is a bloody huge payload for one launch--enough for a whole Skylab, anyway most of one. There won't be a market for that kind of launch very often! But you can downscale, make a 2 engine or 1 engine tank, order smaller SRBs, and launch on scales the market is more responsive to. Such small scales are also more appropriate for a manned craft; something with all the habitability of Orbiter but carrying no main launch engines and no internal cargo for delivery elsewhere, only stuff to be used on the ship on the mission, would be much lighter. Two SSMEs, or even just one, should be adequate to orbit that. We'd only need the heavy version for grand projects--or if space emigration really takes off!

At which point I'd strongly urge NASA to look into developing launch loops or something comparable

The Wet/Dry workshop concept was developed during the 1950s to use existing rockets that had expanded their fuels as stations by opening up the tanks, meaning that they were 'wet' during ascent. A dry workshop is 'Dry' during ascent, the best example is Skylab....Though it (Shadow Master's one-shot use of SSMEs attached to the tank}makes using the external tanks as wet workshops a tad harder. :p

Well, a big wet lab is something you'd want to develop into something grand over the years, and it could use some engines to move it. Or those engines can be detached and installed on some deeper space vehicle.

So what would we call a structure that is lofted as an "outer hull" for the ET or payload. ...
I think e of pi makes it clear enough how problematic this sheath thing is. One possible justification for it would be that one is going for "wet lab" structures on a grand scale, as with the tank-based space station concept. And so, smuggling an outer one-layer "tank" outside the real tank to orbit gets you two tanks. But of course not for the price of one! The thing (assuming we base all this on standard OTL STS sizes) would mass another 30+ tons altogether, so it is two for the price of 2. It is payload, it comes out of your payload budget. If your payload budget is really 120 tons, it is a small price to pay--if what you want is another great big tank. Or big structural panels I guess. Based on STS of OTL, with returnable engine module(s) you are not going to have 120 tons and it makes a bigger hit. I daresay the extra sheath will improve the insulation properties of the tank a bit, and might justify a lighter load of foam insulation, which saves some trouble when you unpack it--you are obliged to prevent the foam from becoming space junk, a layered design might allow elegant detachment and stowage of the stuff.
Also, such a notional “Bigger than OTL ET”, could be fitted with a scaled up return capsule for larger objects to be returned in a cost effective manner to Earth. Did someone mention SSME’s?

Me, me, me mention SSME and returning them! I think the idea of reusing the SSMEs is central to the whole idea of calling something a "reusable" space launch system in the first place. Which is why I urge designing a system to return them all after launch immediately. In early days, when launches are infrequent, it would be essential to incorporate the engines into their capsule system from the get-go so this idea of carrying a separate return module to unship and pack the engines into in orbit is redundant--then. If we get a high volume of launches shifting over to it might save weight and thus further enhance payloads. But I'm not at all sure it would work out to be a lot lighter than integral engine/capsule with immediate and simple detach and return process. The latter sure does save a lot of astronaut or robot tug work in orbit, which is at a premium! If we have a great big space station with hundreds or thousands of residents, the labor cost question shifts in favor of doing work in orbit of course.

It's worth noting that "wet workshops" have never panned out. It turns out that the difficulty and expense of re-fitting the tanks (which require long hours of EVA work by highly, highly paid astronauts who only get to the work site by being lofted into space on billion-dollar rockets.

It has been far cheaper in practice to launch whole dry workshops that are pre-built on Earth by mere high paid workers who don't need to go on an EVA to work inside the construction site and can commute to work in a $9000 car.

Powerful arguments to be sure. It depends though on how much investment we are making for our station, how long we want it to last, whether it will grow into something really really grandiose or if all we want is something like Skylab or a Salyut. In the latter case, of course it is not worthwhile to devote a lot of the limited ration of manned visits to actually building the thing!

But suppose Skylab had been designed with an eye for operating for a decade or more, with a plan to evacuate waste for disposal and ongoing launches to deliver not only crew but a stream of upgrading equipment along with the supplies. Skylab was launched with a variation of the Saturn V that used the second stage to fully reach orbit. Which means that at Main Engine Cut-off, the "spent" Saturn second stage was in orbit along with the Skylab itself. Now suppose that at some modest sacrifice of Skylab's initial capabilities, a tunnel and equipment and reserve air supplies were provided for the first crews to cut into the upper fuel tank (which has been opened to vacuum to vent out any residual hydrogen) and start fitting it out with more stuff? And we have an ongoing supply of upgraded S-1B type rockets and modified Apollo SMs that are lighter, so every mission carries cargo--mostly supplies but also additional stuff to fit the hydrogen tank out with. Gradually we work our way to exploiting the oxygen tank as well. To keep orbit, firing even just one of the J-2 engines even briefly is probably overkill, so those engines are pretty much useless, but compared to the larger stage mass the five of them don't mass all that much so we can afford the dead weight. Or if it is problem, pre-design the attachments with explosive bolts and blow them off, each (or ganged together somehow) with a small deorbiter solid engine to drop them into the atmosphere at a chosen moment.

Doubling up Skylab like this has costs to be sure; we have to invest more to get more. But the crew aren't doing EVAs, they are working inside an air-filled shirtsleeve environment. It isn't 2 for 1, but close to it; we start out with less than 1 considering that we have to dedicate some of Skylab's "dry" mass to refitting the tank from the get-go, but with a dozen missions or so we work it up to nearly 2 as we keep attaching stuff to the tank interior. Conceivably the plan could be to make this version of Skylab the core of a permanent space station, and then the spent stages come in very handy indeed.

Imagine what might be if every module of ISS that was brought up by STS came accompanied by the ET from the launch bringing that component! It would take some extra investment to use each tank but clearly it can pay off.

Since my post to your thread explaining how I attributed 150 tons of orbital capacity to STS (and admitting I was off by 10 or maybe more tons) got lost in various shenanigans, let me say right now--I was counting the mass of the fuel tank, for purposes of comparing to Saturn V lift capability.

Generally we don't want it, certainly not with a space program as constrained as OTL. But if a superior approach to launch logistics might enable a "space rush" compared to OTL, and feedback causes a much grander program, we will find these "disposal" items more useful than they are on our current scale of operations. Labor in space will become relatively less costly and justify more projects like this.
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I think the main issue with wrapping the station walls around the ET for launch is it then begs the question of how the SRBs attach and how the orbiter attaches.

fasquardon
Remember Shadow Master is proposing an in-line launch system. The solids remain and the problem you point out remains with them, but the main hydrogen engines are on the tail of the stack, not sidesaddle. (Where I think they belong!)
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Also consider: With the sheathing method, it becomes necessary to carry the ET up to orbit since it's hard to jettison it from inside the can. That actually eats up something like 20-30 tonnes from the orbital payload....

I seem to have missed quoting the person down thread--bahmaut IIRC--who corrects you on this. The STS launch mode, OTL, required the tankage to be quite adequate to put the mass of the tank as well as Orbiter into orbit; it was then necessary to choose an elliptical orbit the SSME burn put the whole thing into that would dump the Tank into the atmosphere. This meant of course the Orbiter also was at that point on a collision course with the atmosphere!

But, I can't stress this enough, not because the delta-V generated by that point was not adequate to achieve full orbit, as was the case with the second stage of the 3 stage Apollo Lunar version. No, the STS as designed could have put every Orbiter/tank combination into LEO. Lower LEO than the Orbiter generally went to, but high enough that the combo would stay in orbit for a considerable time before decaying. To then deliver a tank massing at least 27 tons on to a high orbit where it would be stable would be a major chore to be sure. But by sacrificing the payload in the cargo bay, it could be done--if necessary, by using some of that volume and mass capacity for supplemental OMS fuel, which might require a redesign never done but certainly could be doable.

Let's see here--say we are in a 100 km orbit initially-that's lower I think than the combination could reach on SSME burn alone, but let's go with it a moment. We can't stay there long, atmospheric drag on the tank would be significant, but let's say we don't dally around; as soon as the orbit is verified, we wait to phase orbits for transfer to let us say ISS. This means we launched to a 52 degree inclination, and are lighter than usual unfortunately, but too bad. We have a full 10 ton load of OMS hypergolic fuel. The Orbiter masses 120 tons, the tank masses 27, all up 147. We need to go from a 100 km orbit to one averaging around 413 km altitude, that's a 313 km ascent, call it equivalent of 300 bearing in mind we are above Earth's surface some distance and the gravity field has fallen off a bit. Roughly speaking, we need to add half the necessary energy to achieve a transfer orbit, then the other half up there to circularize and rendezvous. We need about 94 m/sec delta-V immediately and then another burn of that amount later. The ISP of the OMS was 316 sec so we'd need to use about 8.6 tons of propellant to haul the tank along with the Orbiter to the station. That leaves darn little to deorbit the Orbiter, so it seems safe to say we need some extra out of the payload mass. But not a tremendous amount I'd think; a few tons would do it.

So no, as others have pointed out, depending on just how high an orbit the SSMEs alone can reach for a 52 degree inclination, and how much delta-V was actually lost with each launch by going for the swan dive maneuver to control disposal of the tank, we might actually come out ahead, anyway all it costs is well under 5 tons or so of payload. At worst.

This is why I felt justified in counting the tank mass as mass delivered to orbit. And I admit to being off by maybe 10 tons, so it is really 150 tons in these terms--not 160. But not no measly 120 either!

STS delivered comparable, and superior, total mass to orbit versus Saturn V, and massed nearly a third less on the pad...2050 tons versus 2850.

It is superior technology, well worth developing.

Although I will admit the only reason for the SSMEs to be so damn cutting edge with a 200 atmosphere chamber pressure was to enable a hydrogen engine to operate at all efficiently at sea level launch. And ground-lighting was only necessary because there was no suitable abort mode for the Orbiter crew. Develop an alternate in-line approach with the hydrogen burning upper stage only lighting well up in altitude, and we can get by pretty well with an engine like the J-2S, with a modest 30 atmosphere chamber pressure! improve its ISP a bit and we could have something practically as good as SSME at a lower price in every way--easier to make reusable, or vice versa cheap enough to dispose of.

But I suppose the hydrogen-burning technology of SSME helps explain how come STS seems something like 50 percent more effective than even the mighty Saturn.

The inefficiencies come from demanding a payload a Saturn 1B could have delivered be nannied into orbit by a spaceplane it takes Saturn V power to lift there. By decoupling the engines from the spaceplane we can make it much lighter, leaving capacity for much more cargo. Eliminating the spaceplane completely greatly increases it. With such economies at work we can consider developing the means to bring back the essential engines--which being air-lit, can be much lighter and thus easier to recover, if we haven't decided to just dispose of them instead.

The right Shuttle Decision, in retrospect, it seems to me, was to focus on developing a flyback booster equivalent or somewhat superior to the capability of the Saturn 1B booster, to enable a reusable stage of the same launch capacity as the disposable Saturn 1B second stage to loft something like 20 tons of cargo on a single disposable upper stage using a J-2S engine. And then gradually come to grips with the question of how to get the upper stage engine back home too, maybe with the tankage as well. Meanwhile reusable manned spacecraft will be a side development.

Had they gone that way, it might be a long time before they work up to a 120 ton payload to orbit capacity but when they do, it will be on a well tested basis.
 
Hmmm....
I've found a couple of links that talk about a mass penalty for taking the ET all the way into orbit - but they assume using the OMS system to circularize the orbit. What I am vaguely remembering from decades ago is a proposal that would use ET fuel (rather than OMS) to circularize orbits. Since the Orbiter (iirc) masses more than the tank does, the extra delta-v of LH2 over hypergolics improved total payload to orbit.

Can I find a link? No, not now at least.

See toward the end of my comment 47 below yours. My impression as I said there is that actually every STS launch ever done took a penalty to avoid putting the tank into orbit--higher Orbiter payloads would have been realized with more direct approaches to the desired target orbit on SSME power than were taken. The point was to make sure the spent tank did not become space junk and so the combination was put onto a swan dive orbit with perigee low enough to guarantee the destruction of the tank immediately. More efficient orbits would have left the tanks bumbling around until their orbits decayed at unpredictable times and places, posing navigational hazards in the meantime.

Thus an aggressive program to use the tanks rather than discard them might actually raise payloads other than the tank itself.

I don't have any links either but for years I've seen complaints (or cheerful comments) about the swan dive maneuver, books about the Shuttle boasting that the Orbiter does a dive in order to augment the OMS performance, etc.
 
The Orbiter masses 120 tons, the tank masses 27, all up 147.

Where are you getting these numbers? The most massive orbiter (Columbia) was 80739 kg without payload. The highest mass numbers I have ever seen quoted for the orbiter+payload is 100 tonnes (and those numbers are always used in circumstances where one would not expect the author to give exact numbers). In circumstances where I would expect precision, the mass the shuttle could get to its normal target orbits is generally in the ballpark of 70-90 tonnes (for orbiter+payload), depending on the height and inclination of the orbit.

So you are making the shuttle 20-50 tonnes more capable than it actually was!

fasquardon
 
Well, look at the launch masses all up. From this site I have pretty much every STS launch being in the range 2046-2055 tons. The lightest and heaviest are on the first page so look at the lightest first, the Shuttle "baseline"--Columbia, first launch. We have 1179.5 tons of SRB, external tank at 754.53 tons, subtract these from 2046 and we have 111.97 tons left over--this must be the mass of Columbia on the stack at launch. Nothing gets consumed during launch in Columbia, not until it separates from the tank. If I am not wrong that the tank and Orbiter can be put into orbit without using the OMS, I am justified in saying Columbia, as configured for first launch, could arrive in orbit with tank massing 35 tons for a total of 146.97.

Looking at the next column, SSME Phase 1, we have 2055 tons gross pad mass, and 756.49 tons for the full tank, and 1176.6 for the boosters, so 121.91 for the Orbiter. The tank now only masses 32.24 tons so we get 154.15 to orbit--note that the tank had about 5 more tons of propellant in it.

For the final block of 27 missions using SSME Block II the corresponding figures are 2050.78 all up, 753.03 for the full tank, 1178.2 for the boosters, and the tank masses 26.92 tons dry with the propellent maximized at 726.11 tons. This implies the Orbiter is 119.55 tons all up, and the total load capable to put into orbit is 146.48.

So it appears that more often than not that total I set such store by was indeed under 150 tons, but never under 146. The Orbiters, by inference, all massed at least 112 tons and almost always within a ton or two of 120. This is of course a total of "dry" weight without engines (a bizarre statistic to list, but that's how NASA and Janes liked to list it) the engines, OMS fuel, consumables, supplies, equipment for crew, payload, and the crew themselves. Some places cite 10 tons for OMS fuel but note how Norbert Brügge makes allowances for up to 21.65.

It is a fact that with the "swan dive" tank disposal strategy orbit it was always necessary for Orbiter to maneuver to get into its target orbit, but unless I am much mistaken this was not energetically necessary--all Orbiter launches resulted in the entire 146-154 tons being in an orbit with plenty of energy to be sustainable, it's just that a lower angular momentum was aimed for to bring the perigee low--the apogee if I am not mistaken was more than twice as high as a very low but many-days at least orbit.

The Orbiter's reentry mass was indeed restricted to just under 100 tons per Janes. With a nearly 15 tons down payload included in that, we see very little margin over dry weight with three engines installed for non-cargo. Perhaps "down mass" includes crew, undumped consumables, etc as well as whatever is in the cargo bay? I know they always landed with some reserve OMS propellant too (I believe there was some thought it would enable a go-around in case of a bad landing approach--not sure how well the OMS would fire at sea level though).

Believe me when trying to respond to your earlier query about my insanely high figures for mass to orbit, I tore my hair out trying to pin down just what the nominal mass of an Orbiter on the launch stack was supposed to be all up. Years ago I got the 120 ton figure stuck in my head, and behold the biggest outlier is Columbia--before they stopped painting the fuel tank and lightened the boosters. (After Challenger apparently each booster gained another ton of dry mass, due I suppose to improving the seals). It took a while before it occurred to me to take these convenient all-up mass figures Brügge supplied and subtract the well-known and not very variable SRB and tank masses.
 
It took a while before it occurred to me to take these convenient all-up mass figures Brügge supplied and subtract the well-known and not very variable SRB and tank masses.

So where does Brügge get his numbers from?

I'm a bit dubious the shuttle+payload was quite so heavy because it is so out of line with what any of the shuttle-c variants were expected to do. Getting payload up to 120 tonnes took serious re-engineering, like new main engines, bigger SRB, a new in-line configuration or a combination of all the above.

Heck, even when you include the mass of the payload shroud and the engine pod, most shuttle-c type proposals weren't lifting 120 tonnes.

120 tonnes is also well out of line with any quoted mass for the orbiter I've seen, but I haven't been able to find any references about exactly what is included in the orbiter masses in my source material.

fasquardon
 
So where does Brügge get his numbers from?

I'm a bit dubious the shuttle+payload was quite so heavy because it is so out of line with what any of the shuttle-c variants were expected to do. Getting payload up to 120 tonnes took serious re-engineering, like new main engines, bigger SRB, a new in-line configuration or a combination of all the above.

Well one thing to remember is that the Shuttle was at about 63 miles (~100.8Km) when the ET was depleted and separated, and used it's own OMS to raise itself into its working Orbit.

IIRC the maximum mass of the STS Shuttles was about 123,000 Kg so using some onboard propellant to reach its designated orbit isn't unreasonable to assume.

Shuttle-C and the likes I've not seen adding such an OMS in so the payload would have to be sent directly into the desired orbit, which will cut into peak payload which is the main payload and however much of the payload shroud remains, plus the ET itself. Amounts to a fair deal IMHO.

I could be wrong, but this does seem to make sense to me.
 
I think that the numbers were 120 tones, if we count the fuel, propellant, shuttle, payload, and the ET all together, but that may or may not be correct.

So, if we are going to be using Apollo-esque return vehicles for splash down, OTL sized ones are less than 13' in diameter, and hold 3 people. Here, if we kept them to the size of the OTL shuttle (not that we would need to) what would we get? 15-20' maybe? But what about the 27.6' diameter of the LR? How many people can that safely return? And if it could hold 1 or more engines {SSME or LRME ITTL}, would that cover the returnable loads?

Also, if we JUST want to lift 1 or more RV's into orbit, what is the minimum lift vehicle? A single SRB with a mini LR, with a single RV atop it?

Now for some other questions:
Assuming that an ATL has the goal of an ever increased US presence in space, and that construction jobs are also going to be performed on a continous and increasing basis, what kind of "Construction equipment and tools" are we likely to see, and what effect will they have on improving the speed with which work can be done?

When do we have the capability to loft "Power modules" to keep orbital garages up and running, even if no crew are present? When can we start construction of orbital wharehouses, for storing fuel and supplies, for outward missions?
 
Now I ask you--why not take the thing on the right, and use it for every launch? If you want to send up cargo, send up cargo. If you want to send up people who of course require at least the option of safe return to Earth, make a space bus of some kind, one that mounted up there on top, in addition to advantages e of pi listed, also can more possibly have some kind of escape system. If you need to retrieve something from orbit--not done all that often OTL--make a reentry shell of some kind to launch empty (or with a bit of cargo to make up the maximum launch weight rattling around inside) and stuff the down mass into that when the cargo is stowed. It shouldn't generally be necessary to have crew accompany the down-mass carrier if the down mass comes from a space station. If it is a question of going out to some defective satellite in an isolated orbit and hauling it down, it might be necessary to provide some crew to do the stevedore work, but this just means that 1) a means of this crew escaping a launch gone bad needs to be provided and 2) more mass for general habitability, and mission related equipment.

So here I'm listing 5 or 6 different types of payload. One is unmanned payload as such. OTL the STS designers promised prospective customers for launch that the Orbiter would provide services for the various payloads that would allow them to simplify construction. Also, the limited G-load aimed at in the design (under 3.5 Gs in all circumstances) would ease it as well, so if we want to meet those promises, we need to design the launcher accordingly--it costs in gravity loss hence a bigger system than if we ignored that G limit and shoved stuff into space with peak Gs around 6-8. (This is one reason the Soviets could launch big payloads in the multi-ton range with the relatively modest R-7 rocket base--that system put pretty high G loads on, as did/does Proton). Anyway in addition to modest G loads STS promised cargo support, and the way I envision an STS variant that would be dramatically more economical would involve the payload package, whatever it is, being placed initially in a very low orbit, so some of our total initial mass has to be devoted to fuel and engines to move the the package up to the desired orbit. This is relatively modest, but I've been thinking an all up rule of thumb is that only about 60 percent of the package can be actual revenue payload, on the terms STS promised anyway. We can kick that up near 100 percent by telling the customers their payloads are their business, all STS promises to do is deliver them to that initial low orbit and they have to make their own way from there. But assume for the moment NASA promises the coddling, then a "cargo" load still involves a vehicle bus massing some 10 tons for every 15 tons of revenue payload carried. This is a vehicle, and it is going to cost.

But hey, if you read the Shuttle Decision book it is clear that NASA required work for all their subdivisions; designing a disposable cargo bus and then tailoring it for each launch keeps Marshall and perhaps JPL or Ames busy!

Then, assuming we have a space station, we have need for the station bus; this is a system to deliver some large number of people. If we are working with 120 tons, we will be delivering a hell of a lot of people to what must be some gigantic space station! The trouble here is that it is irresponsible to design a crewed spacecraft that does not have survivable abort contingencies covering the entire launch. Escape from an exploding stack requires substantial delta-V and in the early stages, requires it to be applied very fast, within a second or so, to get adequate distance separation from the disaster in progress. Then it has to land somehow. If we are looking at 8-12 people, it can be done. Several hundred, and no.

It probably makes a lot more sense to limit the size of a pure human transport bus to something realistic launch escape systems can handle and use any extra capacity (out of a 120 tons it would be a lot) for cargo as usual. Presumably this is all cargo destined for the same space station so that works out well. The crewed ship sits on top, the cargo, to be sacrificed in an emergency situation, is below.

Which tells us how missions typical of STS OTL would be designed. A people bus ship with full abort capability and spartan survival conditions rides ahead of a crew expanded habitably/workshop module. We can design the latter to be a disposable cargo with no provision for return to Earth (except in the form of sending it to destruction in the atmosphere for disposal) or we can integrate the core crew bus into a larger landable craft for reuse. This flexible concept again keeps design teams busy for individual missions.

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Anyway, your cargo launcher version sacrifices the main engines, being attached to a non-returnable tank. My proposal is to do your thing on the right (on a different scale probably, though I'd sure hope to work up to yours, and beyond!) but put the engines in some kind of capsule to allow them to return. I think that an SSME can be contained in a structure all up less than 15 tons, perhaps as little as 12--10 would be pushing it I'd admit. And we can approach solving this problem from several directions. Some sort of Gemini or Apollo type capsule that folds its upper cone side like petals of a flower around the exhaust bell of an SSME would be a compact structure that still could allow the 11 degrees gimbaling of the engines STS required, and we'd just design different size tanks to bolt them on to for different sized missions. More elegant, if perhaps heavier, would be to make some sort of space plane or lifting body for each engine and then they could perhaps fly back to runway or pond landings at the launch site after a once-around orbit.

If this system were implemented, you would have to deduct somewhere between 30 and 60 tons from payload for a 3-engine system, probably closer to 36-45 tons. But the engines would go on being reused.

Or of course if you could return the tank too, with engines attached, the reusability would be greater but probably the payload penalty higher.

In addition to matching the reusability of the OTL Shuttle while allowing delivery of larger payloads, this approach allows tailoring of different size of launch vehicle. Unless the greater economy going with greater payloads raises demand tremendously over OTL, causing the "space rush" Shuttle Decision planners assumed would happen, 120 tons to LEO, even with 40 deducted to leave 80, is a bloody huge payload for one launch--enough for a whole Skylab, anyway most of one. There won't be a market for that kind of launch very often! But you can downscale, make a 2 engine or 1 engine tank, order smaller SRBs, and launch on scales the market is more responsive to. Such small scales are also more appropriate for a manned craft; something with all the habitability of Orbiter but carrying no main launch engines and no internal cargo for delivery elsewhere, only stuff to be used on the ship on the mission, would be much lighter. Two SSMEs, or even just one, should be adequate to orbit that. We'd only need the heavy version for grand projects--or if space emigration really takes off!

At which point I'd strongly urge NASA to look into developing launch loops or something comparable
Politics.

Its a rewrite of my 'Seeing Further', which involves Alien artifacts on Mars. While clearly there, Nixon still has the Space Task Group and people thought that they have years to get to Mars, as the Soviets can't even go to the Moon. So NASA, while waiting for a decision, pitches the Shuttle, as well as using Skylab B as interrim station until the Shuttle can be used to build a bigger space station and eventually a ship to go to Mars. To top it off, the CIA got a bit more worrying data on the Soviet Almaz project and some thing called Polyus and believes that the Space Shuttle is needed. Not to mention all those cushy jobs in various constituancies all over the US having voters work there. An interrim solution to keep Skylab B manned continously is an updated Saturn IC, (similar to that from 'Eyes Towards the Sky') and an Apollo II CMS for LEO use only, until the Shuttle can come online.

Come the Soviet annoucement to go to Mars until 1992 and panic on The Hill. NASA finds that they need an HLV to get a Mars ship build reasonably FAST. Saturn V is out of the question, plans got lost, facilities scrapped, that kind of thing. The Shuttle is already feature complete and here come Martin Marietta and Aerojet Rocketdyne, who figure that its easy and cheap to expand with a slightly modified External Tank with a cheaper and easier throw-away version of the SSME, named RS-25S (for single use) on the bottom and more structural elements.

Turns out its not cheap when the cost overruns come in, Congress wants the new HLV on top of the Shuttle, as it would result in even more jobs and the Air Force just ordered two of their own shuttles and are developing weapon platform payloads for it to counter the armed Almaz and Polyus! And than someone at Martin Marrietta flows the idea of using the Shuttle external tanks as wet workshops! To be carried into space with a Shuttle, which can instantly install power systems and allow people to set up shot after orbital insertion! Another new variant for the External Tank and more jobs for Martin Marietta!

Its a big political nightmare. Still The STS HLV won't launch very often. The first is launched to put a 50 tonne Simulated Gravity Habitat into orbit to be docked with the Shuttle Tank wet workshop station.
Well, a big wet lab is something you'd want to develop into something grand over the years, and it could use some engines to move it. Or those engines can be detached and installed on some deeper space vehicle.
I don't think that one or more SSME are the right choice to move a station. Perhaps a few RL-10, but not a bit SSME, let alone three. And you'd want something with a higher exhaust velocity for deep space vehicles anyway.
I think e of pi makes it clear enough how problematic this sheath thing is. One possible justification for it would be that one is going for "wet lab" structures on a grand scale, as with the tank-based space station concept. And so, smuggling an outer one-layer "tank" outside the real tank to orbit gets you two tanks. But of course not for the price of one! The thing (assuming we base all this on standard OTL STS sizes) would mass another 30+ tons altogether, so it is two for the price of 2. It is payload, it comes out of your payload budget. If your payload budget is really 120 tons, it is a small price to pay--if what you want is another great big tank. Or big structural panels I guess. Based on STS of OTL, with returnable engine module(s) you are not going to have 120 tons and it makes a bigger hit. I daresay the extra sheath will improve the insulation properties of the tank a bit, and might justify a lighter load of foam insulation, which saves some trouble when you unpack it--you are obliged to prevent the foam from becoming space junk, a layered design might allow elegant detachment and stowage of the stuff.
Perhaps use a polymer based paint for the insulation to keep it in place. The first external tank was painted white, but NASA dropped the paint to get a bit more payload out of a launch. We all know how that worked out for Columbia... >_>
 
I have in mind a POD that would make the ATL US Space Program budget one tied into Constitutional amendments, and the budget can only be as big or bigger year by year, never smaller! And no, it isn't all coming out of the taxpayers pocketbook, at least not directly.

So I repeat my earlier question, and I will attempt to do a hand drawing {I know, I know}, to show some design components features.
Although I don't plan for this, but rather just something a little bit like it, here is an image that I feel bears discussion.
oyweRXFl.jpg

So, in the above image we see the OTL CSM extracting the LM from the Saturn IVB in orbit. While I don't intend the clamshell like opening for the end of my "Sheathing" cylinder, nor do I intend to have it done without proper tools and equipment. A thought occures to me, did I give the impression when I mentioned an EVA, one or more crew members would be outside and providing all the muscle power to get the job done? If so, that may be where the discrepency exists between my take and that of others, as I see the crew more as a ground guide than as a provider of force.

I'll have too make some very crude hand drawnings to show ideas for what I do want to do. Also, I had an idea for a hybrid idea, that I will talk about when I have the drawings posted.
 
Ok, so I said it would be bad, but these hand drawings are much worse than that, lol.
ULrkoxnl.jpg

Anyway, there are several really crappy drawings, any thoughts?
 
Ok, so I said it would be bad, but these hand drawings are much worse than that, lol. Anyway, there are several really crappy drawings, any thoughts?
A terrible drawing that illustrates the concept isn't terrible at all. :) It looks about like I had been imagining. As I've said before, the sleeve really doesn't add anything that spending half the weight on designing the tank core to be an optimized module wall as well as a tank wouldn't accomplish more elegantly and with less EVA. Even with that improvement by eliminating the sleeve's dead weight, you still face the issues of LEO fitting out and hardware transfer that effect every wetlab proposal.
 
Well one thing to remember is that the Shuttle was at about 63 miles (~100.8Km) when the ET was depleted and separated, and used it's own OMS to raise itself into its working Orbit.

IIRC the maximum mass of the STS Shuttles was about 123,000 Kg so using some onboard propellant to reach its designated orbit isn't unreasonable to assume.

Shuttle-C and the likes I've not seen adding such an OMS in so the payload would have to be sent directly into the desired orbit, which will cut into peak payload which is the main payload and however much of the payload shroud remains, plus the ET itself. Amounts to a fair deal IMHO.

I could be wrong, but this does seem to make sense to me.

Hm. Very interesting indeed. Makes me wonder what a Shuttle C with something like a Centaur stage to put the payload into the final orbit would be like.

I have in mind a POD that would make the ATL US Space Program budget one tied into Constitutional amendments, and the budget can only be as big or bigger year by year, never smaller! And no, it isn't all coming out of the taxpayers pocketbook, at least not directly.

Constitutionally mandated funding for space? That's a pretty big change. Did the Soviets beat the US to the moon and then start building a Lunar colony there?

fasquardon
 
I want to introduce the Hybrid sleeve now. Say the LR/ET is 150ish feet long, and 120ish of that is actually inside the sleeve. Now let’s say that the payload is 60 feet long. Instead of two separate sleeves, we now have a single sleeve 180 long (not counting the end lids). Say the payload is in three expandable disks, each 20 tall by the full width of the interior of the sleeve (they could be rings, or donuts or something else), and that when fully expanded, they are 60 tall. We now get the 180 foot long sleeve filled by three dry labs, with no EVA other than that to extract the LR/ET from the bottom of the sleeve, and the swapping of one lid to the bottom from the top. Does this start to sound better and more doable?

Let’s assume that the two structures are bolted together with 60 bolts (whether or not there is a secondary system holding them in place or not), we need to unfasten these 60 large bolts. A crewman doing this with a power tool, but otherwise unsupported, is going to take some time to accomplish this task. But now suppose that other equipment and tools, designed to anchor the crewmember, the power tool, the 'bolt-bag' and whatever else, has also been provided, such that the fellow doing the work is able to take one bolt out every 5 minutes. That would be a 5 hour job, and that probably means either swapping out guys, or some serious fatigue.

But what if, in addition to the above, because you are planning to do this extraction on most missions, you also loft parts for a cage or ring, that not only encloses the work area and provides stabilization, but allows the deployment of several powered units that position themselves at say, every tenth bolt (so six total), and the crewman in control can monitor them all at once, and then remove 6 bolts at a time, and only take 1 minute per bolt, then the separation could take place within an hour {thinking here that the actual unbolting is ten minutes, but the positioning and removal of the ring/cage and all the tools and such takes the rest of that time}, then the actual extraction could occur, followed by the swapping of lids, and (if we went with the Hybrid design idea) the expansion of the dry labs into their full sized configuration.

Please don't say you want to actually see this concept, based upon what my other ideas looked like when I tried to draw them.

Constitutionally mandated funding for space? That's a pretty big change. Did the Soviets beat the US to the moon and then start building a Lunar colony there?

fasquardon
No, I just mean that, all the way back when it was first concieved, the ATL US Space program is viewed as a part of a much larger program, and one that, developed as planned, is going to need far more funding than it could reasonably be assumed to be able to get, year by year, and so a means of securing that funding is built into the constitution. I have a name for this program:

HE MAN

And no, it is not a joke, and has nothing to do with childrens entertainment.
 
I want to introduce the Hybrid sleeve now. Say the LR/ET is 150ish feet long, and 120ish of that is actually inside the sleeve. Now let’s say that the payload is 60 feet long. Instead of two separate sleeves, we now have a single sleeve 180 long (not counting the end lids). Say the payload is in three expandable disks, each 20 tall by the full width of the interior of the sleeve (they could be rings, or donuts or something else), and that when fully expanded, they are 60 tall. We now get the 180 foot long sleeve filled by three dry labs, with no EVA other than that to extract the LR/ET from the bottom of the sleeve, and the swapping of one lid to the bottom from the top. Does this start to sound better and more doable?
Not really. You also really don't want to carry the payload fairing to orbit like that, particularly not one that's thick enough to be a module wall. That's easily 20-30 tons out of every mission payload for a payload fairing, which you'd normally ditch about halfway through the burn...subtracted directly from the mission payload. You'd get better use of the volume by sticking a hatch into the ET in a small module with a docking port on it and some compressed air tanks on the top/front end of the LR core. All you need to do when you get to space is dock with the permanent module, blow the compressed air through into the tank, and volume for less added mass by justby bolting a 60 ft long module inside the payload shroud to the LR core and cutting a hole (or opening up a pre-installed hatch) into the tanks of the LR. Even just cutting into the tank gets you 150 ft of your proposed volume in one shot.

But what if, in addition to the above, because you are planning to do this extraction on most missions, you also loft parts for a cage or ring, that not only encloses the work area and provides stabilization, but allows the deployment of several powered units that position themselves at say, every tenth bolt (so six total), and the crewman in control can monitor them all at once, and then remove 6 bolts at a time, and only take 1 minute per bolt, then the separation could take place within an hour {thinking here that the actual unbolting is ten minutes, but the positioning and removal of the ring/cage and all the tools and such takes the rest of that time}, then the actual extraction could occur, followed by the swapping of lids, and (if we went with the Hybrid design idea) the expansion of the dry labs into their full sized configuration.
I doubt it'd be that automated--automation is always a tradeoff of time saved per operation times the number of times the operation is performed. Saving two or three EVAs a few times a year isn't really worth the cost of such expansive single-purpose robotics, and you really would have a lot of trouble making that system anything other than single-purpose if you want to do it all in ten minutes. The equipment wouldn't pay. Large jet engines have their fan cases held to the core by (seriously) about 200 bolts apiece. Those are all installed individually even at rates close to a dozen a week. Granted that's on the ground, but robots (like techs) are also a heck of a lot cheaper down here. The better way is to, whenever possible, design the bolts out of the system. Just using the ET/LR as a wetlab as itself is 83% as much volume as your "hybrid sleeve" concept, requires no bolts or inflatable sections, and saves 30 tons per launch that can be spent on the actual payload or on a support module pre-installed and integrated with the tank by engineers on the ground. It still is such a pain in the butt it's not worth doing unless you have absolutely implausible levels of activity in space and guys standing around doing nothing that need busywork--even one LR/ET wetlab would have more volume than the entire ISS. Moreover, the hardest task will remain installing the racks of computers, power cabling, fans, ducts, air processing, and whatever equipment you're actually proposing the fill this house-sized volume with. It's not worth borrowing trouble to try and get an extra few cubic meters per launch with the sleeve, hybrid or otherwise.

No, I just mean that, all the way back when it was first concieved, the ATL US Space program is viewed as a part of a much larger program, and one that, developed as planned, is going to need far more funding than it could reasonably be assumed to be able to get, year by year, and so a means of securing that funding is built into the constitution.
I hope we found alien ruins on the moon or something, because otherwise that entire program is entirely unjustifiable and really silly.
 
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