Author Topic: 9m ITS Development Updates and Discussion Thread  (Read 62383 times)

Online spacenut

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #260 on: 07/28/2017 09:53 PM »
That is what I was also thinking too, 8 around 1 with 12 on the outside ring = 21, or 6 around 1 with 12 on the outside.  I was just thinking he might want to get this operational ASAP. 

It would be cool if he could make a composite upper stage with a sub-scale Raptor and have it reusable.  Raptor + composites would gain a lot of payload, then some would be negated by recovery shielding, unless there was enough fuel so slow it way down from orbital velocity and still land. 

Offline livingjw

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #261 on: 07/29/2017 12:59 AM »
Ideals are much greater than that.

The specific strength of aluminum lithium is about 200MPa/(g/cc). The specific strength of the best available carbon fiber, Toray T1100G (which is very hard to get, by the way), is 3900MPa/(g/cc). That's at the fiber level. If you make a unidirectional composite, it's closer to 2000GPa/(g/cc), still a factor of 10 better. Of course, that's with tensile-dominated structures. Quasi isotropic is less, more like 500-700MPa/(g/cc), but if you're very clever with design, you can utilize unidirectional properties.

So the >30% weight reduction is /after/ "non-ideals."

You have tension in two directions. It cannot be unidirectional.

John

Online lamontagne

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #262 on: 07/29/2017 01:25 AM »
Ideals are much greater than that.

The specific strength of aluminum lithium is about 200MPa/(g/cc). The specific strength of the best available carbon fiber, Toray T1100G (which is very hard to get, by the way), is 3900MPa/(g/cc). That's at the fiber level. If you make a unidirectional composite, it's closer to 2000GPa/(g/cc), still a factor of 10 better. Of course, that's with tensile-dominated structures. Quasi isotropic is less, more like 500-700MPa/(g/cc), but if you're very clever with design, you can utilize unidirectional properties.

So the >30% weight reduction is /after/ "non-ideals."

You have tension in two directions. It cannot be unidirectional.

John
I think what was meant is that it is stronger in one direction than the other.  Perpendicularly.  In composites with oriented fibers, it is stronger in the directions of the fibers.

Offline Robotbeat

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #263 on: 07/29/2017 01:40 AM »
Ideals are much greater than that.

The specific strength of aluminum lithium is about 200MPa/(g/cc). The specific strength of the best available carbon fiber, Toray T1100G (which is very hard to get, by the way), is 3900MPa/(g/cc). That's at the fiber level. If you make a unidirectional composite, it's closer to 2000GPa/(g/cc), still a factor of 10 better. Of course, that's with tensile-dominated structures. Quasi isotropic is less, more like 500-700MPa/(g/cc), but if you're very clever with design, you can utilize unidirectional properties.

So the >30% weight reduction is /after/ "non-ideals."

You have tension in two directions. It cannot be unidirectional.

John
For pressure vessels, there is an ideal wrap angle that takes that into account. It is much better than quasi.
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Online lamontagne

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #264 on: 07/29/2017 03:59 AM »
The original 12m, a 9m cargo with large doors, Dragon and Orion.

Is the 9m core to carry a smaller spaceship as well?  There is a fair amount of space in the nose cone.

ML

Offline Norm38

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #265 on: 07/29/2017 02:10 PM »
Did you make that?  I'd love to see the 9m compared to the shuttle.

Online lamontagne

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #266 on: 07/29/2017 03:40 PM »
Did you make that?  I'd love to see the 9m compared to the shuttle.

Yes, here it is.  I checked the wingspan, all seems correct.

Online lamontagne

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #267 on: 07/29/2017 03:53 PM »
This is not as pretty but clearer.

The very wide shape of the 9m ITS spaceship might require new type ofmultiple satellite holders?

Offline robert_d

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #268 on: 07/29/2017 03:55 PM »
So, starting at the lower engine count (19) what would be the approximate length of the 9M first stage? Can we assume a common bulkhead? If it could fit within Pegasus, SpaceX could just lease it for the first few years of development. AND if 12 meters proves too large, they could think about a 9 meter core version that could handle three Falcon 9 side boosters.   

Offline Barrie

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #269 on: 07/29/2017 04:13 PM »
The very wide shape of the 9m ITS spaceship might require new type ofmultiple satellite holders?

You mean an active dispenser, some kind of carousel which moves sets of satellites into a dispensing position under the door opening?

Online lamontagne

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #270 on: 07/29/2017 04:19 PM »
So, starting at the lower engine count (19) what would be the approximate length of the 9M first stage? Can we assume a common bulkhead? If it could fit within Pegasus, SpaceX could just lease it for the first few years of development. AND if 12 meters proves too large, they could think about a 9 meter core version that could handle three Falcon 9 side boosters.   
The length of the fist stage is payload specific.  The longer the length the higher the payload.  This was made for the 10m version that was discussed earlier.

Online lamontagne

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #271 on: 07/29/2017 04:20 PM »
The very wide shape of the 9m ITS spaceship might require new type ofmultiple satellite holders?

You mean an active dispenser, some kind of carousel which moves sets of satellites into a dispensing position under the door opening?
Yes, a variation on the existing multiple satellite carrier, I suppose.

Offline Robotbeat

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #272 on: 07/29/2017 04:54 PM »
Did you make that?  I'd love to see the 9m compared to the shuttle.

Yes, here it is.  I checked the wingspan, all seems correct.
I like it.

I am increasingly of the opinion that the most comparable vehicle to BFS is Shuttle. Shuttle used drop tanks and landed horizontally, but otherwise quite similar.
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Offline dror

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #273 on: 07/29/2017 06:21 PM »
Did you make that?  I'd love to see the 9m compared to the shuttle.

Yes, here it is.  I checked the wingspan, all seems correct.
I like it.

I am increasingly of the opinion that the most comparable vehicle to BFS is Shuttle. Shuttle used drop tanks and landed horizontally, but otherwise quite similar.

This cargo variant's nose cone is kind of a useless space. Interestingly, it is similar in shape to Dragon's.
If you trade the nose cone for a capsule in front of the cargo ITSy you get somthing even similar to Shuttle, and with LAS.
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Online jpo234

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #274 on: 07/29/2017 06:28 PM »
If they can get the 9m from the factory to the port.  Ships and barges can get it to the Cape.  If they only made 4 per year, that is only one per quarter.  It could move at night or on a weekend.  They could spend a little to get all overhead utilities out of the way so the transfers would be quicker and neater.  I think they have to go wide to get the 100 tons of cargo to space and not have an overly tall rocket.
Why on earth would they want to make 4 per year? If the booster turns out to be as reusable as Elon hopes, one will last decades.
One booster every few years could slowly build up a sizeable fleet.
« Last Edit: 07/29/2017 06:38 PM by jpo234 »

Online jpo234

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #275 on: 07/29/2017 06:33 PM »


The specific strength of the best available carbon fiber, Toray T1100G (which is very hard to get, by the way), is 3900MPa/(g/cc).

Remember: Toray carbon fiber to carry SpaceX's Mars ambitions

Online AncientU

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #276 on: 07/29/2017 07:07 PM »
If they can get the 9m from the factory to the port.  Ships and barges can get it to the Cape.  If they only made 4 per year, that is only one per quarter.  It could move at night or on a weekend.  They could spend a little to get all overhead utilities out of the way so the transfers would be quicker and neater.  I think they have to go wide to get the 100 tons of cargo to space and not have an overly tall rocket.
Why on earth would they want to make 4 per year? If the booster turns out to be as reusable as Elon hopes, one will last decades.
One booster every few years could slowly build up a sizeable fleet.

I think initial build will be 2-3 vehicles (flight boosters) to have depth for testing and qualification, probably built over a couple years.  After that, a steady pace of 2-4 upgraded boosters per year should build a fleet that can serve multiple launch pads with nominally 3 vehicles each.  Of course, various qualification units, STAs, etc. will come first.

Second stages, fairings, and ITSy spaceships (tankers, cargo, and personnel) will be produced in parallel to support testing, qualification, and early operations.  The September reveal v2.0 may give a path through that qualification process and hopefully show the first qual article(s).
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Offline redliox

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #277 on: 07/29/2017 07:19 PM »
This is not as pretty but clearer.

The very wide shape of the 9m ITS spaceship might require new type ofmultiple satellite holders?

Very impressive rendering.  It certainly shows how even a smaller version of ITS would still have vast potential.  I'm having artist Teamonster do some ITS-based renderings as well involving a slightly smaller version of ITS.

In another thread I started, I spoke about the possibility of a mini-ITS being created as a precursor to ITS itself.  In addition to testing purposes I wondered about how a vehicle scaled smaller at a 4:5 could ease mass requirements.  At 4:5 scale ITS would retain 80% of its dimensions but end up being half mass, which puts it near the cusp of direct Mars missions without the refuel rendezvous.  9 meters is 75%, smaller still (assuming the rest of the vehicle is likewise scaled); the mass of a 3:4 scale vehicle would be just over 42% compared to ~51% of a 4:5.  The nominal mass of a fully-loaded ITS was supposed to be something like 400 mt (450 max and 300 min depending on where you want it to go).  A 3:4 scale, 9 meter diameter ITS would presumably weigh 190 mt (at the heftier end), barring factors like number of engines and their influence on mass for instance.  While the 9 meter diameter would influence manufacturing, the end mass would influence the mission itself.

Can anyone double-check to see if 42% mass for 3:4 scale and 51% for 4:5 scale is about right?
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Offline DJPledger

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #278 on: 07/29/2017 08:38 PM »
So, starting at the lower engine count (19) what would be the approximate length of the 9M first stage? Can we assume a common bulkhead? If it could fit within Pegasus, SpaceX could just lease it for the first few years of development. AND if 12 meters proves too large, they could think about a 9 meter core version that could handle three Falcon 9 side boosters.   
SpaceX sure won't go to multiple core designs again after all the trouble with FH. 9m ITS system will stay single core. If they want a bigger ITS system in the future they will go with a larger dia. core.

Offline redliox

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Re: 9m ITS Development Updates and Discussion Thread
« Reply #279 on: 07/29/2017 09:58 PM »
SpaceX sure won't go to multiple core designs again after all the trouble with FH. 9m ITS system will stay single core. If they want a bigger ITS system in the future they will go with a larger dia. core.

Most likely; Elon is definitely urging caution in regards to FH's maiden flight.
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