Really big rockets

ftlwright · 2007-01-25 17:56:33

GCN is correct; the issue is that you are dealing with a serial system rather than a parallel system. To simplify this slightly, if you were calculate for the reliability of the rocket stack (keep in mind this is just the rocket component) you have .9995^49 = .9758 = 97.58% Now keep in mind for most aerospacee systems, 98.5% reliability is typically the lowest you are allowed. Of course, the Russians were forced to use large clusters of rockets due to engineering and materials limitations, but if they had the ability to use larger rockets they would have.

Michael Bloxham · 2007-05-29 05:22:34

I dunno. 97.5% reliability sounds pretty good to me. Especially when you consider how achievable such a huge launcher may be.

I have a question: For any given rocket (lets say 100 tonnes payload), if its equivalent was built and launched from the surface of Mars, how much more payload could it lift to Mars orbit?

GCNRevenger · 2007-05-29 08:12:15

A more than 1-in-50 chance is a bad thing

Antius · 2007-05-29 09:13:09

The Sea Dragon Big Dumb Booster idea may very well be the way to go. Large, but simple pressure-fed engines, with ablative liners, may end up being cheaper per unit of payload lifted than much smaller, high performance engines, which are really only suitable for ballistic missiles.

I have often wondered why NASA has not given more attention to the Big Dumb Booster concept. The shuttle has demonstrated that the technological requiremnets of a reusable vehicle almost automatically make it an expensive vehicle.

Instead, we want rockets rather like coke-cans, which we can use once and then throw away. This sort of design philosophy does not lend itself to complex, turbo-pump rockets made from ultra-expensive alloys. Ultimately I think, even a very large rocket could be extremely simple in design, with only a handful of moving parts (valves on the propellant lines, tank pressurisation equipment and a valve within the engine). Once the design is finalised, the whole thing could be constructyed in a ship yard from carbon steels or aluminium, very cheaply.

GCNRevenger · 2007-05-29 12:55:53

This is largely since SeaDragon is too big, that its such a massive rocket its utility it limited, and its large size would probably hurt its economics versus multiple smaller rockets.

Furthermore, SeaDragon only "works" if its big, that if you make a rocket the same way only smaller, it rapidly loses payload because of its heavy dumb construction with low performance engines.

Michael Bloxham · 2007-05-30 06:03:01

Yeah thanks for the extra discussion, but I was really hoping to know how much effect the lower Mars gravity has on payload. Thanks.

noosfractal · 2007-05-30 06:20:11

It depends on the specific impulse of the propulsion system, but for CH4/O2 it's about 400% to low orbit and 600% to escape. This is a bit misleading because while methane will probably be the Martian fuel of choice for some time to come, terrestrial manufacturing has a wider range of choices, e.g., nuclear-based options.

See Zubrin's ...

The Economic Viability of Mars Colonization
http://www.cbqc.net/mars/docs/m_econom.pdf

Michael Bloxham · 2007-05-31 22:38:00

So if we created a replica of the Saturn V, or the Ares V, and launched it from mars into mars orbit, it would lift about 5 times as much, or 130*5 = 650 tonnes?

noosfractal · 2007-06-01 05:45:38

That's for a 3000 tonne rocket using kerosene & Saturn V engines. You wouldn't actually use the same stages, 'cause they're designed for Earth's gravity well.

Michael Bloxham · 2007-06-04 09:32:10

I understand now why they might call Mars the 'gateway to the stars'.

Returning back to the Paris rocket; I just thought of a method that could be used to launch it (the following applies to the Paris VII configuration):

Imagine that the triangular space between each tank is filled with solid metal (bare with me for a sec) from the top to bottom. Six of these strucutres will act to connect the tanks together, and they also reinforce the whole launch vehicle. Now imagine that these metal structures are bored from the top down along half their length. The bottom half is similarly bored upwards, but with a slightly reduced bore diameter, until the tubes are connected. The smaller bore at the bottom is then machined with a set of grooves, similar to an internal screw thread. However, once this is done, opposite sides of the grooved bore are machined so that they are flush with the bore of the top tube (i.e. the top bore is extended through the grooved bore in two lines) so that half of the grooved area is removed.

Now, round steel columns will be fitted within each tube.
The lower half of each column will be thinner than the top, encased in insulating concrete, while the top half of the steel column will be machined with a matching array of grooves. These grooves will again be machined in a similar manner, so that they interlock with the inside of the lower tube, but can slide freely within it if they are turned a quarter-turn. A smaller section at the bottom of the column will also be machined with these grooves.

At the very top of each column will be a piston which can slide freely within the upper half of the tube and seals against it. Once the columns are fitted by lowering them through the top of the tube (with the column turned a quarter-turn so that it can slide all the way in), a cap is fitted to the top of each tube to seal it. This then creates an air-tight cylinder from which the column can act as a piston.

For additional support, another six tube and column assemblies can be mounted around the periphery of the launch vehicle. Now, at this point I should point out that these tubes will probably not be made out of solid metal, but rather some sort of lighter-weight design will be used.

This is how the vehicle might be assembled in the VAB:

First, a few tube-and-column assemblies are mounted upright onto the MLP platform. For each column, there will be a short bore with interlocking grooves bored into the MLP platform directly beneath it. This is so the bottom section of each column can be lowered into it, and when quarter-turned, they will lock with the MLP. Once a few tube-and-column assemblies are affixed to the MLP, the huge tanks (complete with engines) can be brought in one at a time and bolted to the tube-and-column assemblies. Thus the columns will act as supports as each tank is added, keeping their engines off the ground.

Once all 12 tube-and-column assemblies, and all 7 tanks (including payload), are affixed together, the completed launch vehicle can be rolled out of the VAB using the existing crawler-transporters.

Now heres where it all comes together:

Once the vehicle reaches its designated launch site, the crawler transporter stops, and compressed air is pumped into the top of each tube. At this point, the columns are still locked within the tube and the MLP, but once sufficient pressure is built up to support the dry weight of the launch vehicle on air pressure alone, each column is turned a quarter-turn, unlocking them. Air continues to be pumped so that the vehicle is eventually lifted right into the air; so far that the piston at the top of the column is at the bottom of the upper (smooth-bored) tube. At this point, the columns are again turned a quarter-turn, locking them to both the MLP and the launch vehicle.

All of the vehicles 49 engines are now so far up in the air (maybe 40 meters above the surface of the MLP) that there will be no need for blast diversion channels or any sort of permanent launch pad structure (although a traditional launch tower will probably be maintained for crew loading, systems monitoring, fuel management, and the like).

With all 12 columns locked to the MLP and vehicle, the fuel tanks can now be filled in preperation for lift-off. All 49 engines can then be tested for a few seconds while the columns hold the vehicle down. If all engines are go, all 12 columns are quickly quarter-turned (perhaps explosively); instantly releasing them from the launch vehicle.

To aid their quick release, the grooves may be helically cut at a 45-degree angle: perhaps clockwise at the bottom and anticlockwise at the top, so that when they are turned, the acceleration of the vehicle provides some of the force needed to turn them, and also so that the columns remain anchored to the MLP when they are unlocked from their tubes. Also, the pistons at the top of each column will be designed to safely shear off when the launch vehicle is released.

The four first-stage tanks will each bring with them 2 tube assemblies, and 2 extra engines (in addition to their own 7 engines), when they are spent and released. The two second stage tanks will shed the remaining 4 tube assemblies, so that the middle tank carries no additional mass to orbit.

publiusr · 2007-06-23 12:44:05

Sea Dragon is the way to go. With President Hillary--there won't be any sub orders. But a Sea Dragon SPS combo would give Electric Boat orders.

We just have to tell here than EELVs are made in Alabama--a red state, and that Sea Dragon Ares V are Blue state rockets...

Michael Bloxham · 2007-07-26 00:00:32

I'm voting for Barrack.

Hang on a mo... That 2.5%... is that the chance that one engine out of 49 will fail? That wouldn't be so bad; I reckon you could probably design the rocket to accomodate this sort of failure. Afterall, thats only a decrease of 1/49th of thrust, or roughly a 2% loss. The rocket could probably just burn for a little longer in compensation without incurring too much of a performance penalty. Furthermore, the remaining engines could just be throttled-up to 102% thrust each (or whatever is required to make up for the ~2% loss). No biggie. Unless you're talking catastrophic failure... but engine monitoring systems seem to be pretty good these days and should shut it down before it explodes...

Antius · 2007-07-31 07:06:21

Sea Dragon is the way to go. With President Hillary--there won't be any sub orders. But a Sea Dragon SPS combo would give Electric Boat orders.
We just have to tell here than EELVs are made in Alabama--a red state, and that Sea Dragon Ares V are Blue state rockets...

I often thought that Sea Dragon would have provided a much cheaper and altogether safer way of producing the international space station. The whole station could have been produced enpiece in a workshop on earth and launched into orbit in a single shot. Surely, this would have been much cheaper than the painstaking process of having to assemble the station in orbit, requiring dozens of shuttle launches.

What a waste of time and money the ISS was.

dicktice · 2007-07-31 13:30:28

Ain't 20/20 hind vision grand?

Michael Bloxham · 2007-08-02 05:52:05

Okay, I really want to develop the PARIS concept further. Can anyone help me? Any suggestions? Reference material? Rocket performance calculators, etc?

cjchandler · 2007-08-05 18:45:31

Paris, is a really big rocket, using current technology, right? I'm not sure there's a market for that right now. We can get big things into space, the space shuttle weighs about 100 tons, and the new ares V will be able to have that much payload too, so unless you need something really large sent up in one piece, it'd be cheaper to build it in sections, then the flight rate can be higher and you can at least have the benifits of mass production for the tanks and whatnot. Some thing worth investigating however, we can make fantastic rocket engines- like the SSME, but they cost way too much to be used on a comercial rocket, though they are very efficent, and we can make dirt cheap rocket engines, like the ones in bottle rockets for fireworks, but though cheap they are too inefficent to be used on a comercial rocket, so there must be a certian cost per engine effecency that is the best, but maybe some one has already done this? Seems to mee that maybe current rockets use too effecent of engines.

Michael Bloxham · 2007-08-05 22:06:31

Alright, scratch the whole Paris launcher thingie... What would a clean-slate big dumb launcher look like?

Michael Bloxham · 2007-08-05 22:45:16

Here's something on the russian RLA-150, the design predecessor to the Energia, from Astronautix:

http://www.astronautix.com/lvs/rla150.htm

The RLA cluster method would allow the modules to be built in the factory and thoroughly tested individually without risking the entire launch vehicle.

The modules had a gross mass of about 800 tonnes kgf each, were six metres in diameter and about thirty metres long.

The RLA-150 had a gross lift-off mass 6,000 tonnes, payload to low earth orbit 250 tonnes with six modules as the first stage, and the RLA-120 core.

Glushko insisted that a permanent lunar base and Mars expeditions in the 1980's were achievable. What was needed was a reliable heavy lift launch vehicle, and the RLA approach would achieve this.

The members of the VPK met the proposal with considerable scepticism. The final decision was that the plan had to be reworked. Brezhnev, Keldysh, and Ustinov would insist in the reformulation that the Lox/LH2 technology and capabilities of the US space shuttle had to be duplicated. The end result would be the Energia launch vehicle and Buran space shuttle, with which neither the military or the Soviet engineering community was happy.

I hate the shuttle.

cjchandler · 2007-08-06 07:41:42

Well, my pet big dumb launcher is probably way too dumb but here it is, no moving parts on the main propulsion system- a mix of plastic (hydrocarbons) and high test hydrogen peroxide frozen solid, (~4 C) in a basalt fiber fabic tube. No epoxy, just a layer of plastic underneath the basalt fiber fabric sewn shape. The fuel, and during flight the pressure would keep the shape. One engine a the bottom made of basalt fiber (working temp ~1000 C) and some ablative cooling. For directional control you have a hydrogen peroxide/ propane stage (vaper pressure so no pumps) on top of that with four nozzels that can rotate 90 degrees from straight down to sidways. Then they don't have to throtel and can be used together as the abort system and upper stage. Tow the whole thing in the ocean past the 200 km limit with a tug boat to avoid launch pad costs and pesky regulators.

I do like the idea of a of small tanks clustered, but since I'm counting on a burn through of the pressure wall of the first stage, you'd probably need liquid fueled rockets.

Michael Bloxham · 2007-08-06 11:22:43

What about clustering simple solid rockets, or even hybrid rockets (like the one used in Burt Rutans SpaceShipOne)? Maybe something like OTRAG but with far bigger rockets, and in smaller clusters. Maybe reusable too.

Without considering the huge g-forces, how much payload could a cluster of 7 Shuttle SRB's lift? Consider a reasonably sized H2O2 upper stage, or perhaps even another SRB as the upper stage.

cjchandler · 2007-08-06 19:20:45

I think the SRB could be inproved on with new materials, I mean steel is cheap but if you are reusing it, that isn't such an issue. Basalt fiber and fiberglass cost about 3.00$ a Kg and there are epoxy materials that can handle temperatures up to 1300 c. Another thing to consider is how much staging are you going have to clusters, like all the side boosters falling off together or two by two.

something like this might be good for the upper stage http://www.dunnspace.com/self_pressurized_rockets.htm

I don't really like hybrid rockets as mixing the fuel isn't as easy, but they do have the advantage of being able to turn off. As for calculating the payload- http://en.wikipedia.org/wiki/Rocket_equation is a good start.

Tom Kalbfus · 2007-08-26 07:43:26

What if they just replaced all the windows in Titusville, Cape Canaveral and Cocoa Beach, with heavy duty window panes that can survive the shock of the blast without shattering? It seems like such a trivial concern when your talking about the lifeblood of the local economy. If we can find somewhere else to launch these megaboosters from other than Cape Canaveral then the whole area is out of business. I think Von Braun had an interesting idea of launching these things from Christmas Island or perhaps one of the Hawaiian Islands. Something closer to the equator and away from populated areas would be preferable.

Each SRB segment masses about 150mT. The entire Saturn-V massed about the same as just two *segements* of an SRB.
Four segments (one booster) masses almost the same as the entire Apollo LUT (700mT). The two SRB's used by Shuttle mass MORE than the empty Saturn-V and LUT put together on the MLP - and that doesn't account for the 100mT orbiter, the 30mT External Tank and the typical 15mT payload.
Two SRB's already take the Shuttle stack to the limits of the Crawlers. Two extra segments and a launch tower already necessitate new Crawlers for the Ares-V program. The concrete structure at the Pads is only rated for about 1.5 times the mass of the Shuttle stack when fully fuelled prior to launch, so it could not handle the mass of something that vast.
As for the VAB, its is not the width. The depth of the work platforms do not stretch out anywhere near the new set of SRB's at the far end of the Jupiter-III. What exists now, could only be modified to process half of the vehicle without a ***major*** structural re-build of the main structure inside the 'walls' of the highbays.
And Juptier-III's launch would easily blow out windows all over the cities of Titusville, Cape Canaveral and Cocoa Beach. EPA have already specified that 11m lb thrust would be the maximum allowable at LC-39. J-III is well in excess of that. And if there were a bang on the Pad... Yikes.

Michael Bloxham · 2007-08-29 00:57:30

Yeah, why not?

With current technology, how big can we go?

Is there a limit?

Tom Kalbfus · 2007-09-01 08:40:20

Yeah, why not?
With current technology, how big can we go?
Is there a limit?

That last picture looks like it is built in part out of shuttle external tanks and solid rocket motors. The center rocket looks new however. I assume the rocket motors on the bottom are the equivalent of two Sets of shuttle main engines side by side.

publiusr · 2007-11-09 12:11:18

Quest magazine is to have an issue on Bob Truax--who is in ill health these days

http://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29
http://en.wikipedia.org/wiki/Robert_Truax

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#26 2007-01-25 17:56:33

Re: Really big rockets

#27 2007-05-29 05:22:34

Re: Really big rockets

#28 2007-05-29 08:12:15

Re: Really big rockets

#29 2007-05-29 09:13:09

Re: Really big rockets

#30 2007-05-29 12:55:53

Re: Really big rockets

#31 2007-05-30 06:03:01

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#32 2007-05-30 06:20:11

Re: Really big rockets

#33 2007-05-31 22:38:00

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#34 2007-06-01 05:45:38

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#35 2007-06-04 09:32:10

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#36 2007-06-23 12:44:05

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#37 2007-07-26 00:00:32

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#38 2007-07-31 07:06:21

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#39 2007-07-31 13:30:28

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#40 2007-08-02 05:52:05

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#41 2007-08-05 18:45:31

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#42 2007-08-05 22:06:31

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#43 2007-08-05 22:45:16

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#44 2007-08-06 07:41:42

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#45 2007-08-06 11:22:43

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#46 2007-08-06 19:20:45

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#47 2007-08-26 07:43:26

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#48 2007-08-29 00:57:30

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#49 2007-09-01 08:40:20

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#50 2007-11-09 12:11:18

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