Does physics limit how big you can make a rocket, or is it theoretically possible to launch the Empire State Building into orbit (assuming no limitation on how strong you can make the structure of the rocket doing so)? Thanks.

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Everything I need to know I learned through Googling.

I suspect that the limit would be how much propellant you can make from the materials on the planet. I suspect that it would be hard for it to be taller than about ten miles, but it could be very squat, and have a diameter of many miles.

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That's an awfully big assumption, on the order of "Assume the chickens are spherical". Given infinitely strong Unobtanium, I don't think there is a limit. Given real-world materials, of course there are limits. Too tall an object will collapse under its own weight. Too broad an object, and applying an even force to its underside becomes a problem -- all many square miles of anitoseb's "squat rocket's" underside will have to be covered with rocket nozzles.

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Fiction has to be plausible. Reality is under no such constraint.

Well yes, and they will all have to start at the same time. Definitely an engineering and price obstacle, but still possible.

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If you distribute "small" Saturn V rockets across the continental USA, all "connected" to their neighbors with spools of steel wire, then are they collectively one really big rocket?

What’s the Biggest Rocket possible?



-- Jeff, in Minneapolis

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http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Scott Lowther over at www.up-ship.com has great info. I think Sea Dragon and Nexus are the next two LV we should make after Ares V.

Well, the answer is that..... 'If you assemble this rocket in space (LEO)
then, there is not much of a limit to how big you can build.'
There are practical and engineering issues, of course, but you don't have many of the structural problems of collapsing under it's own weight on the launch pad.

Dan

I expect that somewhere in the Mass of Pallas area you'd run into some trouble with self-gravitation being awfully hard to work around.

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Hi, You make an excellent point. If, for instance, we assembled a ship with 2 cubic miles of water in it for different purpose, and a lot of fuel etc etc
it gets a little unwieldly.

Water would a very good propellant for a large nuclear rocket.

Oh-- Two cubic miles is way, way, way smaller than Pallas. You can
think lots bigger than two cubic miles if gravity is the major concern.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Specific impulse is way too small, resulting in a large amount of mass and a small amount of impulse.

Liquid hydrogen is the fuel of choice in a nuclear thermal rocket.

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

Mugs,

Where are you going to get enough liquid hydrogen in Space to propel a
spacecraft containing two cubic miles of water as payload? It does no
good to have an efficient rocket that has no fuel.

The source of water propellant for your nuclear rocket would be a comet.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Do you mean through fusion? How can water be a propellant?

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As above, so below

A nuclear reactor heats the water to superheated steam and squirts it
out the back. Water is the propellant, but not the fuel. That used to
trip me up a lot. Might do so again.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Why are you pushing around two cubic miles of water?

This is the first time this restriction has been mentioned in this thread!

Therefore, I reject this and reassert the fact that greater efficiency is achieved by using fuels with greater specfic impulse, which is had with fuels of less mass and greater escape velocities.

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

I don't know. All danscope said was, "for different purpose".

But I would guess that if you are building habitats in Space or on
waterless bodies, you would want two cubic miles of water. Hence,
a possible need for a large rocket capable of moving it.

Yes, naturlich. The subject only just came up.

Greater escape velocities? Do you mean exhaust velocities? Larger
Isp gives more efficient propulsion systems, in terms of fuel usage and
total vehicle mass, but it doesn't necessarily give more efficient or
cost-effective transportation systems. If you will permit me to fix a
glaring typo that I just discovered, what I said was:
I didn't say that water would be the best propellant to maximize the
size of a rocket.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

While nuclear materials are chemicals, I don't think nuclear rockets is what the OP had in mind when he wrote chemical rockets.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

It was just a comment in reply to danscope's remark about two cubic miles
of water. I didn't mean to imply that it was a response to the original question.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

If you are going into interstellar space, a large water supply may serve you well, both for propulsion, radiation shielding, life support and other purposes.
If some of it is frozen, it would lend rigidity to the structure.
It remains hypothetical in the extreme, but... the op tests our imagination,
and exercises the mind.
Best regards,

Dan

I think that two cubic miles of water for a manned interstellar expedition
would be a very, very good idea-- if you have the propulsion to move it.
It's the sort of thing you can always find a good use for.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

2 cubic miles of water equals 2.2x10^12 gallons. That's 314 gallons for everyone on the planet. Eventually we may see habitats reaching that size, but they'll have to get there on their own, as there's not enough lift on the planet to move anything more than a tiny fraction of us off-planet.

Yes, sorry - my bad.

Is that a design goal? To make a rocket in space as large as possible? Because the only limit is on materials and prepellant.

Or are we trying to see how large of a rocket we can make here on Earth that'll still make it from Earth to LOE?

If the latter, and we take the carpet approach, we find the same limits.

On the other hand, if we assume we're using the vertical approach, then armed with the strongest materials we have available to us, we could make a 1/2-mile tall tower (if not more) we'd be able to get off the ground, but just barely, before we'd jettison the first stage and light the second.

I think the best approach to ToSeek's question begins with payload. With a requirement to move from, say, KSC to LEO, keep increasing the payload with a conventionalk rocket structure (vertical) until we just can't get there anymore.

Naturally, long before we reach the maximum theoretical size, we exceed the most efficient size given the load, meaning at some point, regardless of load size, it becomes cheaper to distribute the load to two or more rockets than continue to try and build larger ones.

__________________
If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

Physics does not limit the capability to launch heavy payloads, but manufacturing scales and safety issues do.

To get into orbit you need basically to develop sufficient velocity. To keep things relatively simple one can use the ideal rocket equation, which ignores the losses due to gravity and to air resistance, but gets across the basic idea. That equation is

delta V = g Isp ln (initial mass/final mass)

= g Isp ln [(propellant mass + payload mass + inert rocket mass)/(payload mass + inert rocket mass0]

The drivers are thus seen to be the propellant specific impulse (Isp), which is determined by the thermodynamics properties of the chemical species involved and by the mass fraction of the rocket (ratio of propellant mass to the other mass). Generally speaking the mass fraction improves with increasing rocket size, so that is not a big problem.

What does limit the practical size of the rocket is the ability to manufacture it and to provide the necessary launch facilities. There are also issues of explosive safety and range safety that attend increases in scale.

So in principle, you could launch the Empire State Building, but it would require manufacturing infrastructure that does not exist at this time and it would involve the handling of truly massive quantities of explosive material (rocket propellant). An accident with a rocket of that size would be truly impressive -- you might not want to own real estate in Florida at launch time.

Then again.... if you assemble your rocket in LEO as per subassemblies,
you can build a larger rocket with extraordinary charactaristics which could never be launched in one go from Earth.

Dan

It's previously been mentioned that there is no limit in LEO, so that's not the focus (with enough time and effort, we could turn the Moon into a rocket)

The focus involves an Earth to LEO rocket.

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

It is rather difficult to boost the Empire State Building if your rocket is in LEO.

Well, sports fans, When we build large things , we do it in sub assemblies.
We have also learned that if you want to put anything much larger than
Hubble , you may just have to launch components that you can handle.
But, I suppose if you want to experiment with enough SRB's , and you can make a strong enough frame, you can get around 'some' of the problems with building a 'very large' and extraordinary rocket. It's probably cheaper to
build up there.

Dan

That is entirely dependent on the mission.

If your mission is to launch the Empire State Building then having your booster in LEO is not very cost effective. It cannnot do the specified mission.

You're missing the entire thrust of the thread, Dan (pun intended), and it's time to get back on solid ground (pun intende) before we can launch from solid ground to LEO.

You don't launch from LEO to get to LEO... Check the OP, Dan, post numero uno, where the conditions of discussion were set: launch from the ground to Earth's orbit.

As DrRocket said, building your rocket in LEO does nothing to help us get the Empire State Building off the ground.

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

He obviously understood the subject of the thread, guys, thrust included.
Sheesh.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves