Forum designs new rocket to replace the SLS

[Bill Phil]

1 hour ago, ZooNamedGames said:

Like the Saturn V which was designed to carry a "lunar lander" (S-5 designed with the LM still early development) and like it, we can take the liberty of assuming it will be ready when we are.

It is not our responsibility to make sure it is, but if again it prevents you from focusing on the rocket; just remember: the payload is a 70,000lb lump of steel.

You mean... kilograms? As far as I can tell SLS is designed for 70 metric tons to LEO, although it's not a LEO launcher.

[ZooNamedGames]

1 minute ago, Bill Phil said:

You mean... kilograms? As far as I can tell SLS is designed for 70 metric tons to LEO, although it's not a LEO launcher.

Whichever the measurement was, yes. I couldn't remember so I went with what I thought it was. The point being that it's a heavy lump of steel massing just under what the booster should be able to haul into LEO.

[Bill Phil]

1 minute ago, ZooNamedGames said:

Whichever the measurement was, yes. I couldn't remember so I went with what I thought it was. The point being that it's a heavy lump of steel massing just under what the booster should be able to haul into LEO.

No harm no foul.

[tater]

A 35 MT lump of steel is not a payload (early SLS will be 70 MT, not 35). If the goal is interplanetary spacecraft, volume matters. The principle selling point of SLS becomes 140 MT at 8.4m diameter, not just the mass. New Glenn will do that kind of diameter, though a smaller mass. Can the payload be assembled on orbit? Then is the HLV more or less expensive then 2 launches, etc?

The bottom line is that you need the payload first. You can arbitrarily decide you need 8m, then you can find out later that 9m would be better, but you planned the LV before the payload, so you're hosed.

10 hours ago, DDE said:

OK, why hasn't anyone mentioned the Rombus?

To jump back on my Russian high horse, I do wonder what such a vehicle would come out looking like if it used tripropellant motors, with the drop tanks carrying kerolox while the center stage is hydrolox.

450 MT to LEO. Now we're talking. It's also mostly reusable, though those drop tanks are likely a non-trivial expense.

[ZooNamedGames]

7 minutes ago, tater said:

A 35 MT lump of steel is not a payload (early SLS will be 70 MT, not 35). If the goal is interplanetary spacecraft, volume matters. The principle selling point of SLS becomes 140 MT at 8.4m diameter, not just the mass. New Glenn will do that kind of diameter, though a smaller mass. Can the payload be assembled on orbit? Then is the HLV more or less expensive then 2 launches, etc?

The bottom line is that you need the payload first. You can arbitrarily decide you need 8m, then you can find out later that 9m would be better, but you planned the LV before the payload, so you're hosed.

Regardless; that lump of steel is our payload. Congress decides they want NASA to put a 70t lump of steel into orbit.

More payloads will come and they have to adjust to our size.

[SpaceEnthusiast23]

On ‎2017‎-‎05‎-‎20 at 1:51 PM, ZooNamedGames said:

Possibly, but reusability limits range. The idea is we're sacrificing reuse for range.

Plus... am I the only one who thinks that Elon's solution to increased payload mass is just a bit too Kerbalish? In that he goes for the asparagus staging route... I mean it works but it is a bit Kerbal.

Maybe because he plays ksp?

[ZooNamedGames]

6 minutes ago, SpaceEnthusiast23 said:

Maybe because he plays ksp?

Shouldn't come out in your multimillion dollar rockets  

[magnemoe]

2 hours ago, ZooNamedGames said:

Regardless; that lump of steel is our payload. Congress decides they want NASA to put a 70t lump of steel into orbit.

More payloads will come and they have to adjust to our size.

Still an larger diameter payload is pretty fair, and yes its an downside with the falcon superheavy idea, it would be weird with an 8 meter fairing. 
 

[DDE]

5 hours ago, tater said:

though those drop tanks are likely a non-trivial expense.

They are parachute-equipped.

[KSK]

On ‎20‎/‎05‎/‎2017 at 6:51 PM, ZooNamedGames said:

Plus... am I the only one who thinks that Elon's solution to increased payload mass is just a bit too Kerbalish? In that he goes for the asparagus staging route... I mean it works but it is a bit Kerbal.

Depends if you define 'kerbalish' as 'hur hur, moar boosterz and strutz' or not. Besides, SpaceX have abandoned propellant cross-feed as far as I recall, at least for the near future. Leaving them with good old fashioned strap-on boosters, which are a tried and tested way of launching more payload mass.

[kerbiloid]

Rombus tanks look very impractical.

They get spread along the rocket path in several (4? say, 4) places and should be gathered and brought back.
If they splash — they need 4 flotillas with heavy ships across the ocean.
If they land — they do it hardly, otherwise nobody would design a rocket or wing landing.

Anyway, the last tanks are being dropped at near-suborbital speed and must withstand much greater heat and dynamic stress. 
So, either more than a half of the tank set would be overweighted (to make the tanks interchangeable), or they should use several types of tanks on every rocket at once.

And it requires several tens engines, thus 2 x tens of pipelines which makes it looks like an intestine (or like N-1). Mass efficiency and reliability drop tears together.

***

On the other hand, its payload is ~500 t, like of Convair Nexus, Boeing project and any Big Dumb Booster (aka BDB).
ISS — 500 t, Mir — 250 t, Skylab — 90 t.
If instead of a bunch of cans make one big can (to launch it with one rocket), its mass should be, say, 1.5 times less — because shorter pipes and cables, one hull instead of 20, etc.
So, one BDB could launch all those three at once. 

But why need one more ISS/Mir? All primitive experiments already have been repeatedly done in the old 15-20 t modules. 
Zero-G is bad for health, plants grow bad, animals grow bad. It's already known and unlikely needs to be re-proved again and again. 
It's known that a human can withstand zero-G for 1.5-2 years if wants very much, but it's obvious that except Mars flight it matters nothing: Jupiter needs either very fast ship, or artificial gravity. 

To check how badly do the plants grow in low-G you don't need a lunar base with baobabs and bananas. 
A one more 20-t centrifuge module with wheat, rice and soy. (Like the one which was cancelled).

Lunar ground looks trivial and containing nothing to be really needed to mine. 
So, lunar geological studies are significant to understand the Earth/Moon origin, but unlikely one should wait a lunar golden rush.
Thus, small avatarbots and orbital gamma-lasers look more effective than Luna-City.
Large lunar telescope is also a steampunk idea in cyberpunk epoch.

Also even ISS and Mir suffer from the lack of energy (and ISS is already almost flat to give solar panels more space).
So, any 500-t payload just must be nuke-powered.

So, until thermonuke engines appear and an interplanetary flight will take a month, there will be just nothing 500-t to put in on orbit regularly.
Maybe 20 launches total will reach all thinkable purposes for a 500-t payload chemical rocket. Even a 100-t (Saturn V, Energy) were unemployed.

Imho, the only meaningful way to build 100-t chemical rockets is something like UR-700 design, when it's built just by the same technology like the most common rocket - 20-t.
(So, which one you need - that one you make, without bothering with "will it be required in future?")

***

Though, Big Dumb Booster designs look like a half measure. Two-component fuel, tens (or chimerical super-large one) engines.
While their design just cries about one nuke inside a hydrogen tank. Mono-prop, cooled by hydrogen, with the fuel as an anti-neutron protection.
Probably, Big Dumb Boosters will be an intermediate design when chemical engines get gone, while thermonukes yet aren't enough stable.
Then there will be an epoch when such Nukexus will be delivering fission-powered ships to the orbit. And of course, it will drop nothing.

[RCgothic]

Might be worth establishing a list of things we know we can't throw out. E.g:

Vehicle Assembly Building. 125m max height (doors minus mobile platform). Max width 22m.

Michoud Assembly Facility. Max core 10m dia.

[tater]

 

[KAL 9000]

The Saturn Multibody from the Eyes Turned Skywards alternate history beats the SLS hands-down.

[tater]

Any modern design should incorporate either reuse, or extreme cost reduction, IMO. New Glenn is on track to move close to SLS territory (much lower mass to LEO, but similar volumes), and should that LV be successful, the New Armstrong will by definition be an SLS-class vehicle (since it will be able to put a craft on the Moon and return crew, which means ~140 MT in LEO). Given the goals of BO, plus their design strategy (large and robust for reuse) I would argue that any NA LV will actually exceed this. With the sort of resources poured into SLS, ITS could be a thing, or perhaps a better architecture based upon elements of ITS.

[sevenperforce]

As a means of repurposing Shuttle hardware and personnel, the original DIRECT/Jupiter HLV was a great idea. It just didn't have a payload, which meant development crawled and crawled. By now, there's little or no advantage to repurposing Shuttle hardware, and SLS has evolved to use fewer and fewer actual Shuttle parts. IIRC, the early flights may not actually reuse mothballed RD-25s at all.

An aluminum-lithium monocoque-body eight-meter Raptor-derived Falcon X with ten Raptors on the booster and two Raptor Vacs on the upper stage, flying expendable, would be able to deliver 125 tonnes to LEO with a ten-meter-wide fairing. A three-core expendable variant would be able to deliver a whopping 292 tonnes to LEO. And that, for cheaper than a single SLS launch.

[RCgothic]

I'm still running the numbers, but I reckon Michoud and the VAB should be able to construct a 125m x 10m diameter rocket powered by 10-12 F1Bs with a 36m x 12m fairing and 800t to LEO in two stages.

More with strap on boosters which can be up to 4x 6m diameter.

Don't bother man-rating. Just a big dumb booster.

[sevenperforce]

40 minutes ago, RCgothic said:

I'm still running the numbers, but I reckon Michoud and the VAB should be able to construct a 125m x 10m diameter rocket powered by 10-12 F1Bs with a 36m x 12m fairing and 800t to LEO in two stages.

More with strap on boosters which can be up to 4x 6m diameter.

Don't bother man-rating. Just a big dumb booster.

Yeah, you can pretty much just go arbitrarily high....

The real question is, what's the goal? What are we trying to lift?

[DerekL1963]

On 5/20/2017 at 10:14 AM, ZooNamedGames said:

So, let me know what your designs and concepts would be for a 5 billion dollar rocket.

Paper rockets are always cheaper than real rockets.

[monophonic]

2 hours ago, DerekL1963 said:

Paper rockets are always cheaper than real rockets.

I like your suggestion of building the rocket by gluing 5 billion $1 bills together. Does that count as a composite structure?

[tater]

5 hours ago, monophonic said:

I like your suggestion of building the rocket by gluing 5 billion $1 bills together. Does that count as a composite structure?

You could wrap dollar bills (or hundred $ bills) into a hollow cylinder, then drive an oxidizer down the center and ignite it as a hybrid SRB. This could be used to increase the price of a launch, should it fail to meet SLS standards. Ad astra, per pecunia! 

[magnemoe]

18 hours ago, tater said:

Any modern design should incorporate either reuse, or extreme cost reduction, IMO. New Glenn is on track to move close to SLS territory (much lower mass to LEO, but similar volumes), and should that LV be successful, the New Armstrong will by definition be an SLS-class vehicle (since it will be able to put a craft on the Moon and return crew, which means ~140 MT in LEO). Given the goals of BO, plus their design strategy (large and robust for reuse) I would argue that any NA LV will actually exceed this. With the sort of resources poured into SLS, ITS could be a thing, or perhaps a better architecture based upon elements of ITS.

As you will not use an super heavy rocket often re-usability is not important, neither is cost, reliability is as it will often be used for flagship missions. 
An super heavy lifter can be an fully reusable heavy lifter in disposable mode.
This has the benefit of reduced cost because as an often used system and will reduce cost

[Rakaydos]

35 minutes ago, magnemoe said:

As you will not use an super heavy rocket often re-usability is not important, neither is cost, reliability is as it will often be used for flagship missions.

SLS is currently demonstrating one of the problems with that approach- namely that if your rocket construction rate is slower than your workforce turnover... every rocket is your first rocket, and you have to go through the learning process and dumb mistakes all over agai each time.

[tater]

1 hour ago, magnemoe said:

As you will not use an super heavy rocket often re-usability is not important, neither is cost, reliability is as it will often be used for flagship missions. 
An super heavy lifter can be an fully reusable heavy lifter in disposable mode.
This has the benefit of reduced cost because as an often used system and will reduce cost

The SLS program seems to have fixed costs that amount to a couple billion a year just to keep the lights on. If the launch cadence is below some value, then cost absolutely matters. What function is served by spending so much money for 0 launches per year, exactly? If the cadence is upped to 2+, that means that you need 2+ "flagship" missions per year, and those payloads also involve non-trivial expense. Money is finite, cost matters.

We all know that NASA doesn't have the luxury of defining their own goals, or how much they get, or what it is spent on. There are also different priorities at different centers. Marshall loves SLS, most other centers... not so much.

 

[magnemoe]

17 minutes ago, tater said:

The SLS program seems to have fixed costs that amount to a couple billion a year just to keep the lights on. If the launch cadence is below some value, then cost absolutely matters. What function is served by spending so much money for 0 launches per year, exactly? If the cadence is upped to 2+, that means that you need 2+ "flagship" missions per year, and those payloads also involve non-trivial expense. Money is finite, cost matters.

We all know that NASA doesn't have the luxury of defining their own goals, or how much they get, or what it is spent on. There are also different priorities at different centers. Marshall loves SLS, most other centers... not so much.

Yes, cost obviously matter however the fixed cost will be so high that trying to save money on launches has minimal effect and might even end up loosing money because the increased development cost. You also have payload cost.