Starship V4

[redneck]

This goes back a while but what is the source of the "too large" subthread?

Is there any statement or indication that it's possibly too large?

For my part it is the lack of market outside of SpaceX for huge monolithic payloads at this time. Also the constant height increase in Starship/Superheavy looks like a negative factor, requiring constant engine upgrades as well. It seems to me that a nimble competitor can grab a lot of the non-SpaceX market share if they can field a vehicle that is easier on the regulatory front as well as a bit cheaper to operate. As far as I know, an economical 50 to payload vehicle could service most of the available payloads. 

Just as an illustration of a thought. The "obsolescent" Merlin has a vacuum Isp and T/W that isn't far from that of the cutting edge Raptor. A copycat Merlin incorporating lessons since the design was mostly frozen at SpaceX should be dirt cheap to build in quantity. Two of them could run an inexpensive expendable upper stage to deliver 50 tons. Booster just being equivalent to an F9 with more engines. Get the price low enough and it could capture a lot of the non-SpaceX market.

[spacenut]

Sorry, but I did read some where that any larger planes and the runways weren't long enough to handle them.  They have had larger flying wing type planes on the drawing boards.  Then, the runways aren't wide enough.  I've read they design the planes to fit the existing runways.  I do think larger planes could be built.  It is not impossible.  I was saying the airports and runways can't handle anything larger.  I will try to find this article.  The A380 can only land at about 400 commercial airports out of 4,000 in the world which is 10% according to Google AI.  It is also limited by taxiway width.  It was designed as large as possible to meet the existing larger airports.  Also, the large double plane that is used to air launch rockets is even larger and requires a special airport to operate out of.  Not impossible to build larger planes, just nowhere to take off and land.  Same with larger rockets.  Infrastructure is always going to be the limiting factor for an 18m rocket especially away from people, buildings and homes. 

As far as Starship V4, To get the thrust, it seems that the 300 bar thrust per Raptor and 35 engines on the bottom could get the thrust shown.  Then it would be 5,400 bar at least on the Starship.  That is huge.  Then, they could make a 3 core heavy version of the Superheavy booster.  Then landing the center core somewhere downstream that would have to be shipped back.  A wider Starship might then be built to offer larger payloads to orbit.  Then the cost to launch would probably increase.  Single stick rockets seem to be cheaper for reuse. 

[OTV Booster]

V3 is clearly last year "Starship 2" (size, raptor 3 usage in both stages, integrated strut based hot stage ring, gridfins with actuators inside LCH4 tank all match) and V2 is intermediate version that probably wasn't in plan last year and V3 is currently under construction. The overall design of Starship 2/V3 has not changed radically, which we'll see in the near future if it's because the design is good or because the lack of real world testing data due to recent failures

TL;DR: Timeline just slipped, but you are so eager to make shit up

Good that you're resorting to profanity to project baseless accusations onto whomever points out SpaceX's own designators and capabilities (documented in countless outlets since last year's announcement of multiple Starship versions, including this very site), based on vibes and a cursory look at the rendering. Thanks for your contribution.

Catching up on this discussion but I gotta comment.


There is some truth (verifiable facts) in what you say. That's a good basis for expressing scepticism. Unfortunately you project EVERYTHING in as negative a light as possible and either ignore counterpoints or are dismissive of them. This undermines your veracity.


You sound something like this: Naw, they'll never land a booster. Well ok, but they'll never reuse one. Yeah ok, but they'll never make it economically useful.


Figures don't lie but liars can figure. Then there's Elon numbers...

[Oersted]

The A380 can only land at about 400 commercial airports out of 4,000 in the world which is 10% according to Google AI.

Good thing you got AI to help check out the math...  :-)

[JH]

The Airbus A380 and the Russian AN-225 can only land on about 5% of the worlds runways.

Apologies for being pedantic but this should be either the Soviet An-225 or the Ukrainian An-225. It was developed by the Antonov Design Bureau, which is headquartered in Kyiv, and it was operated by a Ukrainian company following the collapse of the Soviet Union. Until Russia destroyed it, of course.

[meekGee]

This goes back a while but what is the source of the "too large" subthread?

Is there any statement or indication that it's possibly too large?

For my part it is the lack of market outside of SpaceX for huge monolithic payloads at this time. Also the constant height increase in Starship/Superheavy looks like a negative factor, requiring constant engine upgrades as well. It seems to me that a nimble competitor can grab a lot of the non-SpaceX market share if they can field a vehicle that is easier on the regulatory front as well as a bit cheaper to operate. As far as I know, an economical 50 to payload vehicle could service most of the available payloads. 

Just as an illustration of a thought. The "obsolescent" Merlin has a vacuum Isp and T/W that isn't far from that of the cutting edge Raptor. A copycat Merlin incorporating lessons since the design was mostly frozen at SpaceX should be dirt cheap to build in quantity. Two of them could run an inexpensive expendable upper stage to deliver 50 tons. Booster just being equivalent to an F9 with more engines. Get the price low enough and it could capture a lot of the non-SpaceX market.

Well we're all agreed that for a specific engine thrust density, the height of the rocket is pre-determined.

So if you're worried about aspect ratio, a wider rocket is better, no?

In other words, for a given engine thrust density and a given aspect ratio, the ideal diameter is a simple calculation.

If Starship is getting too tall, they should go to 12...

Also 12 m is at the border where axial spin might work for low-g during transit.

But - none of this is v4, or any "v" of the current Starship.

[Greg Hullender]

Then, they could make a 3 core heavy version of the Superheavy booster.  Then landing the center core somewhere downstream that would have to be shipped back.  A wider Starship might then be built to offer larger payloads to orbit.  Then the cost to launch would probably increase.  Single stick rockets seem to be cheaper for reuse. 

I think the only reason for a three-core SH would be for fuel tankers, and that only if it pencils out as cheaper than multiple launches of the single-core versions.

[ZachF]

Starship is built at the launch site. Doesn't seem that outlandish.

But I think 9m is going to be plenty for decades. V4 and optimizing it into a workhorse is going to be insanely good. Starship will eventually have more launch payload capacity than any airplane, so I'm not sure 18m is even useful unless you want to launch entire pre-assembled apartment buildings to Mars or something.

What an 18m starship would be good for is bulk propellant transportation. It'd only take 1 of them to fully fuel a 9m Starship to go to mars.

[Vultur]

This goes back a while but what is the source of the "too large" subthread?

Is there any statement or indication that it's possibly too large?

For my part it is the lack of market outside of SpaceX for huge monolithic payloads at this time. Also the constant height increase in Starship/Superheavy looks like a negative factor, requiring constant engine upgrades as well.

I think the cause and effect is the other way: Raptor performance keeps improving, so why not make the rocket taller?

Merlin improved a lot over its development too, to the point that current Merlin is almost a totally different thing from Falcon 1-era Merlin.

It seems to me that a nimble competitor can grab a lot of the non-SpaceX market share if they can field a vehicle that is easier on the regulatory front as well as a bit cheaper to operate. As far as I know, an economical 50 to payload vehicle could service most of the available payloads. 

Maybe, but two difficulties -
1. It's not clear that there are any "nimble" competitors, not comparing to SpaceX development speeds. Rocket Lab maybe - but Neutron is a F9 competitor not a Starship one. And new rockets spool up slowly; Starship will likely have a higher flight rate than Neutron basically permanently. Also, as for regulatory difficulties, SpaceX has a head start - so even if a smaller rocket could be approved faster start to finish that wouldn't let it reach market sooner.

2. I'm not sure how important commercial customer payloads even are for Starship; Starlink v3 alone probably justifies it economically, and then there's NASA HLS.

Just as an illustration of a thought. The "obsolescent" Merlin has a vacuum Isp and T/W that isn't far from that of the cutting edge Raptor. A copycat Merlin incorporating lessons since the design was mostly frozen at SpaceX should be dirt cheap to build in quantity. Two of them could run an inexpensive expendable upper stage to deliver 50 tons. Booster just being equivalent to an F9 with more engines. Get the price low enough and it could capture a lot of the non-SpaceX market.

This could work, maybe. If Starship fails to ever be rapidly reusable.

But if rapid reusability does work, it'll be vastly cheaper even if "suboptimally" sized - probably before a new development starting today could even launch, much less have a launch rate sufficient to take up much market share.

At that point, any vehicle like this is competing for the "we don't want to use SpaceX because we're competitors/to maintain redundancy" market against New Glenn (already flown) and Vulcan (already flown) and Neutron (which will fly way before any new development). ULA arguably has an advantage for government payloads and New Glenn for Kuiper; that doesn't leave all that much. I'm not sure that there's even enough of that market for all three of those to survive long-term.

[volker2020]

I have to admit, I had a totally different take on this width discussion.

The height of the rocket is mostly defined by the m² per engine * thrust, being able to handle the load of the fuel/oxygen.
So basically just a question to bring gravitational loss and maximum g load into the right proportion.

The radius is independent of that and and basically requires less hull, less thermal protection per m³ load.

But the main reason to build wider rockets is the production. To make the rocket slimmer the hull material gets less capable of handling stress while not under low pressure, and the production margins get smaller and smaller, up to the point where have to overbuild them.

Some say, that no one need that much capacity to space. That was the main reason many thought that re usage was unnecessary and  financial unsound. And if Space-X hadn't take matters into there own hands and started with Starlink, these people most likely would still say that.

My personal opinion is, that if you make access to space cheep enough, there will be enterprises willing to use that fact to their advantage. A lot of things, that make absolutely no sense, taken the current prices, will become something, that could become sound for some risk takers, and will become common sense for others, once proven. So maybe there seem to be no market for a 18m rocket. But if that reduces the price of space transport to the right amount, I see no reason, why it won't happen.

[Twark_Main]

This goes back a while but what is the source of the "too large" subthread?

Is there any statement or indication that it's possibly too large?

It was a standalone statement at a point in a discussion that effectively said:  "Bigger is always better" +/- or something to that effect

Yes, that was me.  Rockets want to be as big as possible, +/-.

Someone upthread mentioned that details matter and I agree.  So the analogies to aircraft aren't necessarily apt.  I find the analogies to container ships more interesting in that they always want to be bigger too.  But that analogy is imperfect also.

Just like Bible verses, you can always choose an appropriate analogy to match your desired (and again asserted without a shred of evidence) conclusion. 

[catdlr]

Extra wide was a concept in the past

https://forum.nasaspaceflight.com/index.php?topic=58473.msg2588490#msg2588490

https://forum.nasaspaceflight.com/index.php?topic=58473.msg2588491#msg2588491

https://forum.nasaspaceflight.com/index.php?topic=58473.msg2588493#msg2588493

https://forum.nasaspaceflight.com/index.php?topic=58473.msg2573447#msg2573447

[Twark_Main]

This goes back a while but what is the source of the "too large" subthread?

Is there any statement or indication that it's possibly too large?

For my part it is the lack of market outside of SpaceX for huge monolithic payloads at this time. Also the constant height increase in Starship/Superheavy looks like a negative factor, requiring constant engine upgrades as well. It seems to me that a nimble competitor can grab a lot of the non-SpaceX market share if they can field a vehicle that is easier on the regulatory front as well as a bit cheaper to operate. As far as I know, an economical 50 to payload vehicle could service most of the available payloads.

Regulatory is the "fixed cost" here. It's almost as hard to get a small vehicle certified, so you might as well go big.

I'm curious what you had in mind for "easier on the regulatory front."  Why would an unproven company have an easier time?

Just as an illustration of a thought. The "obsolescent" Merlin has a vacuum Isp and T/W that isn't far from that of the cutting edge Raptor. A copycat Merlin incorporating lessons since the design was mostly frozen at SpaceX should be dirt cheap to build in quantity.

What lessons are those?

Specifically, what lessons give such a big advantage that they overcome the SpaceX home court advantage of... having already developed and built and scaled F9? 

Two of them could run an inexpensive expendable upper stage to deliver 50 tons. Booster just being equivalent to an F9 with more engines. Get the price low enough and it could capture a lot of the non-SpaceX market.

Again, you have all your work ahead of you to show that "F9 except more engines" is actually cheaper than Original Recipe F9.



Funny how one NSF member is arguing that it's obvious that larger vehicles are more economical, and another member is arguing that it's obvious that a smaller vehicle will be more economical.   This goes to show the conclusion is far from foregone, let alone "obvious."

[OTV Booster]

FWIW, constantly changing the rocket’s name and version is a good way to make it tough for people to keep track* of which promise aligned with what version of what ship.

V2 had a bad string of failures… well now that’s V1.5! See? No SS V2 failures!

* tough enough that it requires the effort of many people across multiple sites and social media platforms to keep track

Naw, Elon is 'naming' challenged. It's been a constant since the F9.


It is no good treating as cynical villainy things that merely exhibit the incapacity of our minds to live consistently.
   - H. G. Wells

[Starship Trooper]

If Starship is getting too tall, they should go to 12...
Also 12 m is at the border where axial spin might work for low-g during transit.

The whole subject of using spin for artificial gravity is quite interesting and not simple.  A little 'gravity' might be better than none for some purposes, establishing up/down orientation, dropped things would end up on the 'floor', pour drinks into a glass etc.  However for maintaining muscle mass and bone density you would want a significant fraction of Earth gravity.

Then there is the the issue of how much angular velocity, rpm, people can tolerate without having vertigo.  Most people can tolerate a few rpm for awhile.  But, for a long term home-like environment like a cylinder habitat, 1 rpm is considered to be the desired upper limit.

Here's the rub, to get 1g at 1 rpm you need a rotational diameter of almost 1800 metres, so 12 metres is nothing.  The better solution is to link a pair of starships up with a 1800 metre tether and spin them up to 1 rpm.  You get comfy 1g all the way to Mars.  Or, if you are considering that the crew will be on Mars for years, you can use a 700 metre tether to generate Mars gravity.  But wide Starships don't really add anything.

[Twark_Main]

If Starship is getting too tall, they should go to 12...
Also 12 m is at the border where axial spin might work for low-g during transit.

The whole subject of using spin for artificial gravity is quite interesting and not simple.  A little 'gravity' might be better than none for some purposes, establishing up/down orientation, dropped things would end up on the 'floor', pour drinks into a glass etc.  However for maintaining muscle mass and bone density you would want a significant fraction of Earth gravity.

Then there is the the issue of how much angular velocity, rpm, people can tolerate without having vertigo.  Most people can tolerate a few rpm for awhile.  But, for a long term home-like environment like a cylinder habitat, 1 rpm is considered to be the desired upper limit.

Here's the rub, to get 1g at 1 rpm you need a rotational diameter of almost 1800 metres, so 12 metres is nothing.  The better solution is to link a pair of starships up with a 1800 metre tether and spin them up to 1 rpm.  You get comfy 1g all the way to Mars.  Or, if you are considering that the crew will be on Mars for years, you can use a 700 metre tether to generate Mars gravity.  But wide Starships don't really add anything.

They said "low-g" not 1 g, and 1 RPM is an old and highly conservative number.

[Starship Trooper]

If Starship is getting too tall, they should go to 12...
Also 12 m is at the border where axial spin might work for low-g during transit.

The whole subject of using spin for artificial gravity is quite interesting and not simple.  A little 'gravity' might be better than none for some purposes, establishing up/down orientation, dropped things would end up on the 'floor', pour drinks into a glass etc.  However for maintaining muscle mass and bone density you would want a significant fraction of Earth gravity.

Then there is the the issue of how much angular velocity, rpm, people can tolerate without having vertigo.  Most people can tolerate a few rpm for awhile.  But, for a long term home-like environment like a cylinder habitat, 1 rpm is considered to be the desired upper limit.

Here's the rub, to get 1g at 1 rpm you need a rotational diameter of almost 1800 metres, so 12 metres is nothing.  The better solution is to link a pair of starships up with a 1800 metre tether and spin them up to 1 rpm.  You get comfy 1g all the way to Mars.  Or, if you are considering that the crew will be on Mars for years, you can use a 700 metre tether to generate Mars gravity.  But wide Starships don't really add anything.

They said "low-g" not 1 g, and 1 RPM is an old and highly conservative number.

Ok:
Starship Radius = 6 metres
Choose your RPM, and the evidence that it is tolerable long term by most people
(Note, for a 6 metre radius cylinder a standing short person's head would experience the acceleration of a 4.5 metre radius)
Calculate the Centrifugal Acceleration at the feet for your RPM, and what utility it would have other than the minor benefits I listed above.

[Metalskin]

FWIW, constantly changing the rocket’s name and version is a good way to make it tough for people to keep track* of which promise aligned with what version of what ship.

V2 had a bad string of failures… well now that’s V1.5! See? No SS V2 failures!

* tough enough that it requires the effort of many people across multiple sites and social media platforms to keep track

Naw, Elon is 'naming' challenged. It's been a constant since the F9.


It is no good treating as cynical villainy things that merely exhibit the incapacity of our minds to live consistently.
   - H. G. Wells

To be honest, how I see the version changes over time is something I've seen a lot in agile software development.  Bascially reaction to change, what is released changes, which changes the way what is released is called. I don't know if this is why Elon is "'naming' challenged", but considering his background, maybe ¯\_(ツ)_/¯

[spacenut]

There was Sea Dragon concept 75' in diameter (about 23-24m) in diameter, that would be towed out to sea and set vertical to launch directly from the ocean.  It was to deliver 550 tons to LEO.  It was two stage, with reuse of the large first stage with second stage expendable.  NASA was interested, but budget cuts cancelled the idea.  It was to be built at a navy shipyard.  It was to have one large pressure fed engine and made from steel. 

Very large rockets are possible, but would require sea launch and possibly built and navy shipyards.  Something to consider in the future. 

I would think the largest rocket currently that might be built is a 12m Starship/Superheavy with one more ring of engines inside the outer 2m.  Probably 50+ engines on the booster.  Raptor 3 may be maxing out on what it can do at about 300 ton thrust.  New infrastructure would have to be built to even handle 12m.  Then you have a maximum height, thicker material to hold the fuel/lox.  Is the trade off worth it?  Or would newer engines with more thrust be needed, thus more development cost.  I don't see larger rockets by SpaceX for at least another 10 years or so. 

[redneck]

Regulatory is the "fixed cost" here. It's almost as hard to get a small vehicle certified, so you might as well go big.

I'm curious what you had in mind for "easier on the regulatory front."  Why would an unproven company have an easier time?

It seems to me that building a new facility for a Starship class vehicle will have more hurdles than building a facility for a somewhat larger Falcon class. Unproven company though is a sticking point. So many of the legacy players should have been blazing the trail that SpaceX is doing. Too extensively discussed already to rehash. Probably some combination of legacy and SpaceX alumni if it happens.