Poll

What diameter do you think the Mini-ITS will have?

3.7 m (12 ft) like Falcon 9
0 (0%)
5 m (16.4 ft) like Delta IV
3 (2.8%)
8.4 m (27.6 ft) like the Shuttle ET
50 (46.3%)
10.1 m (33.0 ft) like the Saturn V
45 (41.7%)
12.2 m (40 ft) like the Falcon Heavy width
3 (2.8%)
Even bigger!
3 (2.8%)
None, it won't be built at all.
4 (3.7%)

Total Members Voted: 108

Voting closed: 08/20/2017 03:09 PM


Author Topic: POLL: Mini-ITS Diameter  (Read 4943 times)

Online QuantumG

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POLL: Mini-ITS Diameter
« on: 07/21/2017 12:47 AM »
Vote and explain your reasoning below. I know this is a contentious question, but let's try to keep chatter to a minimum.
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Online QuantumG

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Re: POLL: Mini-ITS Diameter
« Reply #1 on: 07/21/2017 12:52 AM »
I voted for 8.4 (or close enough) as I really do think SpaceX will try to make the Mini-ITS cores in Hawthorne and road transport them to a nearby port. That puts a limit on how big they can be, and the transport of the Shuttle External Tank to the Science Center is the best example of moving something that big. If they build the cores somewhere else they could do something wider, in which case I'd go for 12 m as they already have Falcon Heavy handling hardware at the launch pads. Hard to imagine anything wider than that!
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Offline Rebel44

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Re: POLL: Mini-ITS Diameter
« Reply #2 on: 07/21/2017 01:03 AM »
IMO: 9-10 meters (voted 10 meters) - which is around maximum that can be manufactured in Hawthorne and still get to port.
« Last Edit: 07/21/2017 01:04 AM by Rebel44 »

Offline tesla

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Re: POLL: Mini-ITS Diameter
« Reply #3 on: 07/21/2017 01:08 AM »
Even bigger, because that's what it takes to land 100+ people on Mars at once.  ;)

Online QuantumG

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Re: POLL: Mini-ITS Diameter
« Reply #4 on: 07/21/2017 01:15 AM »
Well, the original ITS proposal was only 12 m diameter. The spacecraft was to hammer-head to 17 m, but that's not the core diameter :)
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Offline spacenut

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Re: POLL: Mini-ITS Diameter
« Reply #5 on: 07/21/2017 02:02 AM »
I voted 10m because of Hawthorn maximum building height.  I would prefer a short squat 12m that could be stretched and more engines added at some point in the future with a new launch pad somewhere. 

10m same as Saturn, but with 10-12m lbs thrust to launch from the cape flame trenches.  Since it is going to be resuable booster it would probably only match Saturn V LEO capabilities or about 100+ tons, since the ITS has to land, and the booster has to land. 

They would probably have to build a huge supply of F9/FH cores before switching to the ITS booster and spacecraft.  Also get re-usability mastered before manufacturing. 

Also, won't they have to have 3 prototypes?  One for crew, one for cargo, and one for a tanker?  Or can they be made modular?  Lots of questions. 

If they go with 8.4, they could make it at Mchloud facility in Louisiana using same tooling as SLS unless SLS is steel instead of aluminum.  But, 8.4 limits the number of engines they can add and stretching it with improved engines would make 8.4 look like the F9 on steroids.  Therefore I think wider is better for future ability to stretch the core and handle the ITS.

Offline IanThePineapple

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Re: POLL: Mini-ITS Diameter
« Reply #6 on: 07/21/2017 02:06 AM »
I'm guessing Shuttle ET width, as it will be much larger than Falcon to help gain experience with larger diameter tanks, but not so large that they would need massive infrastructure modifications.
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Offline savuporo

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Re: POLL: Mini-ITS Diameter
« Reply #7 on: 07/21/2017 02:06 AM »
10.1 because that will exactly equal to how many months it will take to announce something new.
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Offline 2552

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Re: POLL: Mini-ITS Diameter
« Reply #8 on: 07/21/2017 02:27 AM »
5 to 6 meters, with 7 to 9 Raptors. With the plan to use it for Earth-Moon system missions as well as Mars missions, a smaller vehicle that is reused more (especially the spaceship) makes sense to me, and could possibly replace F9/FH.

Edit: 5 to 6 meters if still using linerless carbon fiber tankage, 6 to 7 meters if aluminum-lithium.
« Last Edit: 07/21/2017 07:45 AM by 2552 »

Offline envy887

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Re: POLL: Mini-ITS Diameter
« Reply #9 on: 07/21/2017 02:28 AM »
9 or 10 meters and squat, stretch it and add engines later. Could eventually reach 250 tonnes reusable.

Offline RedLineTrain

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Re: POLL: Mini-ITS Diameter
« Reply #10 on: 07/21/2017 02:33 AM »
I voted 10 meters because the item to look at for max width at Hawthorne is probably the Shuttle Orbiter rather than the External Tank.  Mini-ITS will probably be stubby -- perhaps shorter than the External Tank.
« Last Edit: 07/21/2017 02:35 AM by RedLineTrain »

Online QuantumG

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Re: POLL: Mini-ITS Diameter
« Reply #11 on: 07/21/2017 02:37 AM »
23.79 m (78.06 ft) diameter would be one heck of a core ;)

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Offline RedLineTrain

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Re: POLL: Mini-ITS Diameter
« Reply #12 on: 07/21/2017 02:45 AM »
They cut down a lot of trees to move the orbiter.  I doubt L.A. would be so understanding for a mere Mini-ITS.  So something less than the orbiter, something more than the External Tank.

Or whatever... ;)

Offline KelvinZero

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Re: POLL: Mini-ITS Diameter
« Reply #13 on: 07/21/2017 03:13 AM »
I voted 10m because of Hawthorn maximum building height.  I would prefer a short squat 12m that could be stretched and more engines added at some point in the future with a new launch pad somewhere.
I sort of wish I had voted 12m now. No one has voted it at this point. Short squat 12m is always the outcome that was coolest to me.

I just went 10m because I really have no information, except 10m is the value already thrown around for other projects by other companies, so I assume it can be handled without special provision for SpaceX.

One reason to argue for 12m is that they already made a 12m tank. And in my opinion SpaceX actually thinks very very carefully about things like existing markets. Elon is a showman who welcomes Fanboys painting him as Noah building a massive boat in the middle of dry land with no possible purpose, but there is no reason for him to explain to his competitors ahead of time how he intends to out compete them right now and tomorrow and all the years between here and there.
« Last Edit: 07/21/2017 03:26 AM by KelvinZero »

Offline Lar

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Re: POLL: Mini-ITS Diameter
« Reply #14 on: 07/21/2017 03:35 AM »
Saturn diameter feels right to me so that's what I voted. I think it could be taken out of Hawthorne but not easily. So I expect them  not to build any, or many, there.
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Offline RonM

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Re: POLL: Mini-ITS Diameter
« Reply #15 on: 07/21/2017 05:00 AM »
I voted for 8.4 (or close enough) as I really do think SpaceX will try to make the Mini-ITS cores in Hawthorne and road transport them to a nearby port. That puts a limit on how big they can be, and the transport of the Shuttle External Tank to the Science Center is the best example of moving something that big.

I agree. It would be a hassle to move something that large from Hawthorne to the port, but since the mini-ITS will be reusable, SpaceX only needs to build a few of them.

Online MATTBLAK

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Re: POLL: Mini-ITS Diameter
« Reply #16 on: 07/21/2017 05:16 AM »
I chose 8.4 meters because there's lots of precedent for transporting around stages/fuel tanks of that size. Elon could hire or buy a barge of the same class and type that used to transport the Shuttle E.T.s - though with a housing customised to protect it from the elements as it goes.
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Re: POLL: Mini-ITS Diameter
« Reply #17 on: 07/21/2017 05:20 AM »
5 to 6 meters, with 7 to 9 Raptors. With the plan to use it for Earth-Moon system missions as well as Mars missions, a smaller vehicle that is reused more (especially the spaceship) makes sense to me, and could possibly replace F9/FH.
That size of vehicle would be a reasonable match for Zubrin's 'Mars Direct' ships. Some of the similar technologies and concepts will be used, too.
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Offline RocketmanUS

Re: POLL: Mini-ITS Diameter
« Reply #18 on: 07/21/2017 05:46 AM »
Voted 8.4 m

Figure could fit at least 18 engines. Enough power for 2nd stage reuse or mini BFS.
Good enough for crewed Mars exploration missions.
Not to big and not to small. Could launch from LC-39A or LC-39B
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Offline jongoff

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Re: POLL: Mini-ITS Diameter
« Reply #19 on: 07/21/2017 06:48 AM »
I voted 8.4m diameter for a few reasons:

1- My guess is that the mini-BFR/ITS is shooting for replacing Falcon Heavy, which would suggest a similar or slightly higher prop loading (Methane and Raptor is more efficient, but you don't have as many stages, which is less efficient).

2- LOX/Methane is significantly lower density than LOX/CH4, which also suggests a bigger diameter.

3- If they're trying to do Falcon Heavy payload in a single-stick design, with a LOX/Methane upper stage, they probably need to go bigger than 5m because Vulcan is LOX/Methane with a LOX/LH2 upper stage, and is still sub FH capacity. Which kind of implies either a really tall vehicle or a wider one--my gut suggests wider. Sure this isn't perfect because Raptor in theory is shooting for higher performance than BE-4, but I'm skeptical that SpaceX could get a FH class vehicle crammed into a 5 or 5.4m diameter body.

4- If you keep the stack height similar to Falcon Heavy (which is already pretty tall), tripling the propellant, and going to ~2/3 the density gets you pretty close to 8m diameter.

5- And as others have pointed out there is some precedent for 8.4m diameter tanks being shipped around in that area.

10m or bigger could also be possible, but 8.4m is already pretty big, and my super crude, I'm too lazy to do anything more sophisticated BOTEs suggest 8.4m is big enough to do the job.

That's my $.02 at 12:48am, FWIW, YMMV, etc

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