Flight Question What is the maximm theoretical size for a luncher?

[fausto]

I want create a luncher as big as the Empire State Building! I know it's possible in orbiter, but in the reality? Not in terms of costs, but in terms of physical limits? For example, there are involvements about air friction?
How big can be a luncher?

 

[RisingFury]

Anything will fly if you stick a big enough motor on it...

 

[DanHawkridge]

Yes pretty much as long as you have a big enough engine to move the rocket. It gets slightly problematic when the thrust being produced is getting significant enough to actually move the Earth into a different orbit, but at that size/weight the top of the rocket is probably nearing space anyway!

 

[MeDiCS]

And you'd need to develop a whole new class of super-strong, extra-light materials.

 

[Artlav]

And you'd need to develop a whole new class of super-strong, extra-light materials.

Or extra-powerful nukes.
Anything will fly if you put strong enough nuke under it.

Proposed Orion type craft designs allowed up to 6 million tons of payload to orbit capacity.

So, really, the Earth breaking strength is the limit.

 

[SiberianTiger]

It looks like UR-700M was the longest rocket out of the all designs considered in the real world:

 

[Ark]

Theoretically you can go pretty damn big. However, you run into problems when firing your engines means toasting most of the Cape.

 

[SiberianTiger]

Theoretically you can go pretty damn big. However, you run into problems when firing your engines means toasting most of the Cape.

Foremost, the problems begin due to buildup of the acoustic load on the rocket's structure itself with increase of power of the engines (least to say, to the launch complex too - but we at least can make it a single use thing). In other word, the extra-powerful engines are so loud that they are capable to break apart anything.

I'm just wondering, if the problem persists for the 1st stage graded nuclear engines, too?

 

[Andy44]

About the Orion designs: Freeman Dyson and his colleagues were designing nuclear pulse-propelled starships which were hundreds of meters in diameter. They were generation ships for exploring Alpha Centauri. One wonders how these machines were meant to be launched.

 

[Ark]

Foremost, the problems begin due to buildup of the acoustic load on the rocket's structure itself with increase of power of the engines (least to say, to the launch complex too - but we at least can make it a single use thing). In other word, the extra-powerful engines are so loud that they are capable to break apart anything.

I'm just wondering, if the problem persists for the 1st stage graded nuclear engines, too?

Now that would be nuts, watching sound alone rip stuff apart.

 

[Andy44]

The sound of the shuttle's SRBs can blow stuff off the orbiter if they didn't use water sound suppression.

I seem to recall that back in the 1950s there was an experimental turboprop engine installed in an F-84 fighter jet which had very short prop blades whose tips exceeded Mach 1 when the engine was at idle. No ground personell could go anywhere near the aircraft when it was turned up because the godawful noise would cause vomiting and injure internal organs.

Noise is a big deal.

 

[Ark]

To launch REALLY big stuff we'd have to buy remote islands and install launch structures. Places like Midway or Iwo.

 

[kevinvr]

Wouldn't it be easier to build a base and a factory on the moon, ship all the materials there , and launch from there?

 

[Sunhillow]

I seem to recall that back in the 1950s there was an experimental turboprop engine installed in an F-84 fighter jet which had very short prop blades whose tips exceeded Mach 1 when the engine was at idle. No ground personell could go anywhere near the aircraft when it was turned up because the godawful noise would cause vomiting and injure internal organs.
Noise is a big deal.

Things like this are still in air:

the TU-95 strategic bomber, a turboprop driven plane that can reach jet speed. I would really like to hear one of them on full power
The blade tips exceed Mach 1, diameter is over 5,5 m

 

[fausto]

Lunching an enourmus payload from the Moon would not be easier than lunching it from Earth! You have to build appropriate facilities on the Moon and it means risks and problems. The advantages of less gravity to win would be no more convenient, at that point!
Is it wrong?
I suppose that lunchers are similar to ships:
bigger= more efficent
A GREAT facility located in some remote places near the equator woud be the best solution!

 

[Sunhillow]

One problem of very big launchers would be: the lower structure parts have to be robust enough to carry their own weight plus upper stages and payload. And they should stand a reasonable acceleration, unless you don't want to waste fuel for hovering slowly upward.

I guess if only liquid boosters will be used, noise and vibration won't be as bad as with the Shuttle SRBs.

Does anyone know if pogo oscillation is mainly a problem for liquid propelled rockets?

 

[Andy44]

Solids have a type of osillation which is longitudinal but, strictly speaking, is not "pogo", which is a characteristic of fuel slosh affecting the turbopumps, in turn affecting the thrust level, such that as the turbopumps start to spin up or down to compensate they act in phase to reinforce the oscillation. (I think, someone correct me if I'm wrong)

As for the max size of a booster, think of it this way: what's the max size for a skyscraper? Take that and imagine filling it with liquid and thrusting it into space, and you realize you will have to make it smaller to start with. Obviously there are limits based on the limits of the construction materials.

When you say "theoretical" you have to specify what's included in your theory. Using pure rocket science math, there is no theoretical limit. You just add more fuel and more thrust. But if you take materials into account, limits pop up quickly and the problem becomes much more complicated. No one knows for sure how big a building we can build; we're still learning and some people even think a space elevator is possible. Certainly we don't know for sure the exact size limit for a rocket.

 

[DanHawkridge]

Is the pogo ocillation the type that affected the central engine of the Apollo 13 Saturn V flight? I m aware that the movment of the middle engine was stretching the rocket by about 15cm significantly reducing the pump rate onto the J-1 engines. You could just use 1 'large' engine to counteract that but it starts getting rather impossible after a while! I suppose the real question is why would you need it?

 

[Vanguard]

You want a *really* big ship? Build a giant engine... face it's thrust towards the sky... turn it on... that's one big spaceship