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#1 2019-08-31 10:13:29

Oldfart1939
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Registered: 2016-11-26
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Musk announces upgraded Starship 2.0

I like the fact that Elon "thinks big!" This article was posted in Business Insider:
https://www.businessinsider.com/elon-mu … ter-2019-8

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#2 2019-08-31 10:41:47

RobertDyck
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Re: Musk announces upgraded Starship 2.0

Well, he certainly thinks big. I still think it would be better to build a dedicated ship to go from Earth orbit to Mars orbit and back. Use aerocapture at both planets. Heat shield made of Nextel 440 fabric, which is the fabric that NASA's Ames Research Center selected for advanced thermal blankets called DurAFRSI. That's a synthetic ceramic fabric. Carbon fibre can withstand more heat, but carbon fibre is not as durable so not as reusable. Elon's design requires on-orbit refuelling anyway. And a dedicated in-space ship could use rotation for artificial gravity. Think of a wheel behind a giant fabric umbrella heat shield. Robert Zubrin's idea of a tether connecting a habitat to the spent upper stage is perfect for a small craft such as Mars Direct, but for a colonization ship that's 8 times the habitable volume of Starship? Make that a wheel.

For on-orbit refuelling, he could use the first Starship to ferry passengers from Earth to the interplanetary ship. And the original Starship fuel tanker could refuel it as well. On Mars, leave an original Starship to act as Mars shuttle. So no need for Starship 2, instead a dedicated in-space ship.

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#3 2019-08-31 11:02:37

Oldfart1939
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Re: Musk announces upgraded Starship 2.0

My initial thought was this Starship 2.0 could be a single load to orbit tanker, capable of a "one-stop refuelling" for Starship 1.0. Instead of 6-8 individual launches, one big load and be done with it.

Last edited by Oldfart1939 (2019-08-31 11:13:34)

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#4 2019-08-31 11:39:17

RobertDyck
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Re: Musk announces upgraded Starship 2.0

Math: For the ship to have Mars gravity (38% Earth) with a spin rate of 3 RPM, the radius to the floor must be 38.3838 metres. The formula from "The Case for Mars" 1996 soft cover edition, page 123: F=(0.0011)W²R where F is centrifugal force in Earth gravities, W is spin rate in RPM, R is length of the spin arm in metres.

That makes the diameter 76.7676 metres. Circumference = πD (Pi * Diameter) = 241.1728 metres (791.25 feet). If the ring width is 14 metres (45.93 feet) then floor area is 3,376.419 m² (36,343 square feet). If ceiling is 2.4 metres (8 feet), then volume is 7,850 m³. Starship is said to have 9 m diameter and 1,000 m³ volume.

::Edit::
Found an image of "Hermes" from the movie "The Martian". The image shows the ring from edge to the hub, with a woman standing in a window. The woman is actress Jessica Castain, her ankles and feet are below the window. She is 5' 4" tall, so subtracting 8" for her feet below the window, that's 4' 8" showing. That makes the radius from centre of rotation to outer hull of the ring module 17.8 metres. You realize the ring for the colonial transport described above is twice that diameter? And it's a solid ring, not 4 disconnected modules? And the ship described above is the same volume as Elon's Starship two?!?!?
MV5BMjIwMzM4Njg3Nl5BMl5BanBnXkFtZTgwOTQ1NTI5NTE@._V1_.jpg
martian_20thCenturyFox.jpg

Last edited by RobertDyck (2019-08-31 17:36:48)

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#5 2019-08-31 11:47:31

RobertDyck
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Re: Musk announces upgraded Starship 2.0

Oldfart1939, that might be. This raises the issue of on-orbit propellant transfer. The SpaceX first design showed the tanker beside the ship. This would require a propellant bladder. Apollo used synthetic rubber for thruster quad propellant tanks. The bladder separated propellant from pressurant (helium), so only propellant came out. For LOX/LCH4 you could use PCTFE film instead. It doesn't become brittle until -240°C, so colder than either densified LOX or densified LCH4. The film can be thinner than rubber so lighter. Later depictions of Starship showed the tanker but-end to but-end with the ship, with the tanker applying light acceleration to cause propellant to settle to the tank bottom. This requires propellant and alters the orbit. Wouldn't a bladder work better?

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#6 2019-08-31 11:51:05

louis
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Re: Musk announces upgraded Starship 2.0

Beat you to that on another thread! smile

Here is the video link I included:


https://www.youtube.com/watch?v=t5kj1Bx1YrQ


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#7 2019-08-31 12:27:32

louis
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Re: Musk announces upgraded Starship 2.0

This seems like a bit of overkill to me...

I remain of the view that, for at least a few decades, we won't be in the era of mass colonisation on Mars.  We are probably talking about bases with up to a max of 10,000 people during the first 50 years. Would there really be a need for a Starship 2.0? You might be talking about a max transfer of maybe 4,000 people every two years - perhaps 50 return Starships, requiring 250 LEO fuelling launches over two months, just under 3 a day.

I can see problems with launching such a massive craft as the Starship 2.0 from mainland USA.  How big will mass be in relation to Saturn V - 4 or 5 times bigger? What sort of noise will that make? I think there might be environmental issues.

Maybe in 30-50 years you would need something like  Starship 2.0. But one would hope by then that we have alternative transport systems which don't deploy such "traumatic" propulsion systems.

One thing I am wondering - could you use a  Starship 2.0 for direct transport to Mars at any time you chose (with proportionally smaller payload and more propellant). If so, that might well be Musk's aim, as I can see that would be a huge advance for Mars colonisation.

Last edited by louis (2019-08-31 15:06:44)


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#8 2019-08-31 15:20:35

Oldfart1939
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Re: Musk announces upgraded Starship 2.0

I somehow think this may be a "rocket too far," in his planning. Maybe as a follow-up after successes on his Starship 1.0 design?

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#9 2019-08-31 17:27:45

SpaceNut
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Re: Musk announces upgraded Starship 2.0

The increase in mass would mean for the current direction for starship is we can not keep making it taller so going wider is the answer and its also the answer for mars thin atmospher as well. The plus for the larger diameter is not spininning or tumbling end over end to create artifical gravity but a spiral instead can be done.

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#10 2019-09-01 12:39:00

Calliban
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Re: Musk announces upgraded Starship 2.0

Correct me if I'm wrong here.  There would appear to be fundamental limits to the height of a rocket vehicle.  Ultimately, engine pressure would need to be proportional to height, as increasing height means more mass per unit of cross sectional area, and hence, the need for higher engine pressure to enact enough force to allow acceleration without intolerable gravity losses.  Higher engine pressure means higher pumping power and higher rates of heat transfer within the combustion chamber, throat and engine cone.  I'm not sure at what point engine pressure would become a limiting factor, but doubling rocket height would appear to be less straight forward than doubling diameter.


Interested in space science, engineering and technology.

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#11 2019-09-01 15:05:32

Oldfart1939
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Re: Musk announces upgraded Starship 2.0

I think you are confusing engine pressure with total thrust required to move such a mass. This is NOT the issue at hand.

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#12 2019-09-01 17:50:15

SpaceNut
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Re: Musk announces upgraded Starship 2.0

Pumps are used to create the greater level of fuel flow for the engines and the tanks can also be pressurized as well to make it happen.
More engine are used to get a higher level of thrust but that comes with the mass penalty of needing a greater level of fuel for the length of the burn time needed.

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#13 2019-09-09 07:33:31

elderflower
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Re: Musk announces upgraded Starship 2.0

Pumps require a certain amount of pressure at the feed inlet from the tank. This is known as net positive suction head. It isn't likely to be an issue on a planet at launch (it will have been designed in). and definitely not whilst there is motor thrust. However, when there is freefall there is no pressure available to push the liquid out of the tank and into the pump. So the tank must be pressurised or thrusters must be fired to settle the liquid in the tank or conceivably artificial gravity could be employed if you don't want to run the engine, just transfer fluids from one tank or vehicle to another.

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#14 2019-09-09 18:34:21

SpaceNut
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Re: Musk announces upgraded Starship 2.0

From article

"finished rocket may stand about 387 feet (118 meters) tall and 60 feet (18 meters) in diameter." overall size eightfold, enabling even more ambitious trips to Mars. The same calculation on the next-generation Starship — assuming its height also doubles, to about 775 feet (236 meters) — gives an approximate volume of 60 million liters.

5d321b89a209d313df35e046-960-658.png

The higher mass of the second stage will mean reinforcing the first stage to carry that extra mass of the much larger second stage. Even  when trying to convert as much as one can to composite there are going to be issues....

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#15 2019-09-09 19:47:19

louis
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From: UK
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Re: Musk announces upgraded Starship 2.0

Is that diagram right?  Because, if so, Saturn V must have had a diameter greater than 18 metres - which I very much doubt. Looks like the Starship/SuperHeavy Mark I has just been stretched.

SpaceNut wrote:

From article

"finished rocket may stand about 387 feet (118 meters) tall and 60 feet (18 meters) in diameter." overall size eightfold, enabling even more ambitious trips to Mars. The same calculation on the next-generation Starship — assuming its height also doubles, to about 775 feet (236 meters) — gives an approximate volume of 60 million liters.

https://amp.businessinsider.com/images/ … 60-658.png

The higher mass of the second stage will mean reinforcing the first stage to carry that extra mass of the much larger second stage. Even  when trying to convert as much as one can to composite there are going to be issues....


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#16 2019-09-09 20:23:15

Oldfart1939
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Re: Musk announces upgraded Starship 2.0

I suspect the drawings of Starship I  represent 9 meters in diameter, not 18. Relative sizes seem correct. Saturn V would be dwarfed by Starship 2.0.

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#17 2019-09-09 20:36:19

louis
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Re: Musk announces upgraded Starship 2.0

The diagram has a figure for "Starship Mk 1" and then "Starship".  There is no "Starship 1".

SpaceNut's quote says "finished rocket may stand about 387 feet (118 meters) tall and 60 feet (18 meters) in diameter."

The only figure with the 387 feet designation is the "Starship".  So it is the Starship which is claimed to be 18 metres in diameter but if you look at the next figure you will see the Saturn V diameter is GREATER than that of the Starship. Did the Saturn V have a diameter of more than 18 metres? Er - no.


Oldfart1939 wrote:

I suspect the drawings of Starship I  represent 9 meters in diameter, not 18. Relative sizes seem correct. Saturn V would be dwarfed by Starship 2.0.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#18 2019-09-09 21:33:46

SpaceNut
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Re: Musk announces upgraded Starship 2.0

https://en.wikipedia.org/wiki/Saturn_V

First stage – S-IC
Length    138.0 ft (42.1 m)
Diameter    33.0 ft (10.1 m)

Second stage – S-II
Length    81.5 ft (24.8 m)
Diameter    33.0 ft (10.1 m)

Super_heavy-lift_launch_vehicles.png

Saturn V payload is indicated as 140t for a hieght of 110.6m

https://en.wikipedia.org/wiki/SpaceX_Starship

Mk 1 and Mk2 are Two orbital prototype ships With 3 raptor engines.

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#19 2019-09-11 20:18:22

kbd512
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Re: Musk announces upgraded Starship 2.0

I happen to agree with Robert that if we ever have a launch vehicle with a 1,000t payload, then a purpose-built in-space-only spacecraft is a better design than something that must function as a reusable rocket upper stage.  There are just too many conflicting design requirements for one vehicle to function optimally in all environments.  Vertically landing a rocket powered vehicle 2/3rds the length of an A380 fuselage, 3 times the A380's fuselage diameter, and likely close to the A380's maximum takeoff weight, on an unimproved surface is just crazy talk.  Even if you can somehow make that work under the right conditions, it still flies in the face of what we know about the stability of such a craft without excessively heavy and large support structures.  There has to be a reason why we don't already do that here on Earth for military purposes and it probably relates to the impracticality of such a vehicle.

I'd much rather have a 10,000t ship that stays in orbit than a 1000t ship that tries to launch from the surface of two different planets with wildly varying atmospheres and land vertically without a steel reinforced concrete launch pad.  There's no practical reason why we can't use shorter and wider orbital ferries that exhibit fewer stability problems, especially on the moon or Mars.  ISS weighs 450t and the Saturn V was 2,950t, so a 10,000t interplanetary transport ship is roughly equivalent to 3 Saturn V's.  Given a ship of that weight class we should be able to make it quite durable, with a useful service life measured in decades.

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#20 2019-09-11 20:29:49

SpaceNut
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Re: Musk announces upgraded Starship 2.0

Which also makes the current BFR starship combo just as silly for that same reasons as one design does not fit both....
design a throwawy second stage with the payload being the transit vehicle for all others to dock to.
Launch a special second stage expendable with earth departure stage booster to attach to the ship.

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#21 2019-09-12 04:01:01

louis
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Re: Musk announces upgraded Starship 2.0

I think that would be the ideal, ultimately...and of course, we could also create Artificial Gravity for the journey to Mars (not least because I think there is a likelihood of increasing concern about pollution and general environmental impact from multiple launches).  Ideally we would probably just use laser/microbeam power to lift people and goods up to orbit, one ton at a time. Or maybe we will find a way to launch to orbit the Virgin Galactic way. 

But in terms of getting to Mars and setting up a base as soon as possible, I think Musk's Starship is the perfect answer and it can multi-task for LEO satellite launches, ISS supply, and Lunar Tourism/Exploration which makes a lot of sense.

kbd512 wrote:

I happen to agree with Robert that if we ever have a launch vehicle with a 1,000t payload, then a purpose-built in-space-only spacecraft is a better design than something that must function as a reusable rocket upper stage.  There are just too many conflicting design requirements for one vehicle to function optimally in all environments.  Vertically landing a rocket powered vehicle 2/3rds the length of an A380 fuselage, 3 times the A380's fuselage diameter, and likely close to the A380's maximum takeoff weight, on an unimproved surface is just crazy talk.  Even if you can somehow make that work under the right conditions, it still flies in the face of what we know about the stability of such a craft without excessively heavy and large support structures.  There has to be a reason why we don't already do that here on Earth for military purposes and it probably relates to the impracticality of such a vehicle.

I'd much rather have a 10,000t ship that stays in orbit than a 1000t ship that tries to launch from the surface of two different planets with wildly varying atmospheres and land vertically without a steel reinforced concrete launch pad.  There's no practical reason why we can't use shorter and wider orbital ferries that exhibit fewer stability problems, especially on the moon or Mars.  ISS weighs 450t and the Saturn V was 2,950t, so a 10,000t interplanetary transport ship is roughly equivalent to 3 Saturn V's.  Given a ship of that weight class we should be able to make it quite durable, with a useful service life measured in decades.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#22 2019-09-12 04:08:40

louis
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Re: Musk announces upgraded Starship 2.0

Don't think anyone had an answer as to whether you could get to Mars more quickly in a Starship 2.0 than in the standard version...any thoughts?


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#23 2019-09-12 14:52:03

elderflower
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Re: Musk announces upgraded Starship 2.0

Most of the launch mass of Saturn V or any other rocket for that matter doesn't make it to LEO never mind escape velocity. A 10000 tonne object would require hundreds of launches of very big rockets just to get it to LEO, where it could be assembled. Then it would have to be fuelled so that it could enter a transfer orbit.  10000 te is a very long way off. Maybe you slipped the decimal point by a digit?

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#24 2019-09-12 19:42:23

kbd512
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Re: Musk announces upgraded Starship 2.0

Elderflower,

No zeros were misplaced.  I meant exactly what I typed.  If we can launch 1,000t to LEO at a crack with this new Starship variant, or even just 500t, then a 10,000t ship represents between 10 and 20 launches.  SpaceX will have to launch at least that many times just to support the first mission, so why not build transports in the same tonnage class as a Flight III Arleigh Burke Destroyer while we're at it?

If we had ships like this, there's no way we wouldn't use them for every last dollar that they're worth.  To my way of thinking, a small fleet of such ships to transit between the planets is worth more money than all the Gold and Platinum in the world.  This is about establishing the space economy.  All economies run off of delivered tonnage.  In all logistics operations, delivered tonnage is what counts.

These ships would run off of pulsed fusion and D-T pellets clad in light metals, mostly mined in space after initial fueling.  The power to initiate fusion would be supplied by small fission reactors, most likely TRIGA type reactors that can deliver GW-class pulses of power to fire the lasers that accelerate and pre-heat the metal-clad D-T pellets at that magical 10km/s through a constant-power electromagnetic field to initiate fusion.  That's already been proven to work quite well here on Earth, just not for generating electrical power.  Since no electrical power whatsoever would be supplied by the fusion reactions, just thrust from the vaporized metal cladding, it's not a problem for our ships.  Each 1cm diameter D-T marble produces about 8kN of thrust.  The pellets have the advantage of not requiring much in the way of pressurization to store and force feed to the "gun" orifice.

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#25 2019-09-12 19:59:00

SpaceNut
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Re: Musk announces upgraded Starship 2.0

Current incantation of starship has a fuel load of 1200t for just a second stage.....

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