Author Topic: MCT Speculation and Discussion Thread 4  (Read 625771 times)

Offline nadreck

Re: MCT Speculation and Discussion Thread 4
« Reply #1480 on: 01/26/2016 11:51 PM »
Maybe a poll forecasting Musk's coming out of the closet date?

How about a poll with the top ten BFS/BFR designs and mission architectures?

Who compiles the 1000 page pdf document detailing these?
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline The Amazing Catstronaut

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Re: MCT Speculation and Discussion Thread 4
« Reply #1481 on: 01/26/2016 11:54 PM »
Musk already dropped a date for when he wants to reveal the architecture: September 26-30.
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Offline philw1776

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Re: MCT Speculation and Discussion Thread 4
« Reply #1482 on: 01/27/2016 12:37 AM »
Musk already dropped a date for when he wants to reveal the architecture: September 26-30.

Great!  Let's hope he makes this date.  So much for the Big Reveal coming up Real Soon Now. :)

I think it's wise to hold off (Dammit!) because it's best done after a successful FH launch which hopefully will occur by then, although I'm concerned.  And it's best to thoroughly vet the major architecture points and sleep on them.  Also returning several cores and seeing what if any changes a BFR launcher would need.

No real point on a Poll for the date now. I of course was picking September.  :)
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Offline DJPledger

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Re: MCT Speculation and Discussion Thread 4
« Reply #1483 on: 01/27/2016 08:29 AM »
Musk already dropped a date for when he wants to reveal the architecture: September 26-30.
Hopefully all the speculation on BFR/MCT system will end then.

Offline nadreck

Re: MCT Speculation and Discussion Thread 4
« Reply #1484 on: 01/27/2016 01:29 PM »
Musk already dropped a date for when he wants to reveal the architecture: September 26-30.
Hopefully all the speculation on BFR/MCT system will end then.

You mean just like all speculation on the Falcon 9, Dragon 2, and Falcon Heavy have stopped?
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline BSenna

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Re: MCT Speculation and Discussion Thread 4
« Reply #1485 on: 01/27/2016 02:58 PM »
Maybe a poll forecasting Musk's coming out of the closet date?

How about a poll with the top ten BFS/BFR designs and mission architectures?

Who compiles the 1000 page pdf document detailing these?

Maybe only the main features. Could be an spreadsheet with the info, data or ilustration of each part of the mission. Then, it woud be an Y or N for each point when the architecture is revealed.

Offline BSenna

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Re: MCT Speculation and Discussion Thread 4
« Reply #1486 on: 01/27/2016 03:16 PM »
Yes, BSenna. You and I are thinking alike.

I do not have a specific concept of the MCT design; I just react to new info as I discover it. I have some experience as a engineering project manager but my principle role now is "Idea Man." But as a team player I am ready to change my concepts when a better idea is presented. So if you and I were to work together, you should take the lead on what the MCT design is likely to be.

My arena would be an idea about a structure that the MCT architecture will require: an in-space propellant depot. If interested, it has 3 threads on this forum so far, starting with this:
http://forum.nasaspaceflight.com/index.php?topic=38146.0

I took a look at the propellant depot project and it looks great, very refined. But unfortunately is too much for my technical limitations, so, I didn't undestood it completely, but I trust on you guys!

I could start a 3d model, but my habilities are really limited. I have some doubts:

I assume that the MCTs which will trasport the fuel to LEO are of a similar size and mass of the crewed MCT, so, they're not full of fuel when reach the depot, right? If It's the case, would there be any advantage on leaving only a smaler fuel tank on each of these missions and returning to land to fly again on the same role, thus reducing the total fleet of MCT-SIIs) and also reducing the total mass of the complete transit to mars vehicle? Or The rockets on these MCTs are also necessary to throw the complete vehicle to Mars?

Once on Mars, just the crewd MCT would land, refuel and return to meet the rest of the vehicle?

Then, all 7 MCTs would land on Earth for refurbishing?
« Last Edit: 01/27/2016 03:17 PM by BSenna »

Offline The Amazing Catstronaut

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Re: MCT Speculation and Discussion Thread 4
« Reply #1487 on: 01/27/2016 05:37 PM »


You mean just like all speculation on the Falcon 9, Dragon 2, and Falcon Heavy have stopped?

People will stop suggesting completely alternative architectures and instead speculate about architecture upgrades. That will cut some of the 'Dastardly and Muttley in Their Flying Machines/Catch that pigeon' proposals.
« Last Edit: 01/27/2016 05:38 PM by The Amazing Catstronaut »
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Offline nadreck

Re: MCT Speculation and Discussion Thread 4
« Reply #1488 on: 01/27/2016 05:55 PM »


You mean just like all speculation on the Falcon 9, Dragon 2, and Falcon Heavy have stopped?

People will stop suggesting completely alternative architectures and instead speculate about architecture upgrades. That will cut some of the 'Dastardly and Muttley in Their Flying Machines/Catch that pigeon' proposals.

Excuse my cynicism but even before the USAF award to develop a raptor or raptor variant for FH and F9 upper stage use it had been discussed for a long time here along with potential F9 or FH new reusable US.  So I fully expect that whatever Musk announces in September some variants in both overall architecture (including depot/refuelling, upper stage types, dependencies on site preparation at Mars, Mars ISRU and depots, SEP on BFS, BFS return to Earth surface, LEO, LM-1/2, etc) and specific details (BFS engine arrangement, TPS, BFB recovery, BFS ECLSS, BFS cargo arrangemnt etc) will still get debated well outside guidelines of where SpaceX says it will be going.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline Ionmars

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Re: MCT Speculation and Discussion Thread 4
« Reply #1489 on: 01/27/2016 09:32 PM »
Excuse my cynicism but even before the USAF award to develop a raptor or raptor variant for FH and F9 upper stage use it had been discussed for a long time here along with potential F9 or FH new reusable US.  So I fully expect that whatever Musk announces in September some variants in both overall architecture (including depot/refuelling, upper stage types, dependencies on site preparation at Mars, Mars ISRU and depots, SEP on BFS, BFS return to Earth surface, LEO, LM-1/2, etc) and specific details (BFS engine arrangement, TPS, BFB recovery, BFS ECLSS, BFS cargo arrangemnt etc) will still get debated well outside guidelines of where SpaceX says it will be going.
The end of speculation lies just beyond Andromeda Galaxy.
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Offline Ionmars

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Re: MCT Speculation and Discussion Thread 4
« Reply #1490 on: 01/27/2016 11:10 PM »
I took a look at the propellant depot project and it looks great, very refined. But unfortunately is too much for my technical limitations, so, I didn't undestood it completely, but I trust on you guys!

I could start a 3d model, but my habilities are really limited. I have some doubts:

I assume that the MCTs which will trasport the fuel to LEO are of a similar size and mass of the crewed MCT, so, they're not full of fuel when reach the depot, right? If It's the case, would there be any advantage on leaving only a smaler fuel tank on each of these missions and returning to land to fly again on the same role, thus reducing the total fleet of MCT-SIIs) and also reducing the total mass of the complete transit to mars vehicle? Or The rockets on these MCTs are also necessary to throw the complete vehicle to Mars?

Once on Mars, just the crewd MCT would land, refuel and return to meet the rest of the vehicle?

Then, all 7 MCTs would land on Earth for refurbishing?
Here's the way I see the Depot working:

The first half dozen or so trips to Mars will carry cargo to set up habitats, ISRU machinery, and remote-contolled equipment. These preliminary forays will prepare a base for humans who will arrive later. A cargo MCT launching from Earth will be heavily loaded; it will use up essentially all its fuel just to get to the depot in orbit. It will require a refill before proceeding any further.
 
We will have a tanker variant of MCT, which has the same basic outer shell as a cargo or passenger version, but will be hollowed out as a big fuel carrier. The volume that would otherwise be cargo volume will be devoted to big fuel tanks. This could be just an expansion of the the main tanks that extend into the the cargo space. Its principle function will be to haul fuel from Earth to the depot, probably about 250 tonnes of CH4 and LOX in each trip. . Three or four loads of fuel must be transferred to the cargo-MCT before it can proceed to Mars.

We could just make a series of trips to the waiting cargo ship and sequentially fill it up. But having a depot allows us to fill up multiple cargo ships and launch as a fleet to Mars. This is the stated intent of SpaceX.

So tanker #1 arrives at the depot and docks at a berth. Tanker #2 arrives at the depot and transfers its fuel load to tanker #1, reserving just enough fuel to return to Earth via propulsive landing. These tankers are highly reusable and require little maintenance between flights, like an airplane. Tanker #2 refills at the launch site and launches again to the depot. It again transfers its fuel load to tanker #1 and returns to the launch site. Now tanker # 1 has enough fuel in its tanks to service one cargo MCT. And because we have six berths at the depot, we can perform this procedure three times simultaneously using six tanker MCTs.

Now three cargo ships arrive at the depot and dock beside three refilled tankers. The tankers transfer their fuel loads to the cargo ships and return to Earth.

We have three cargo carriers ready to trek to Mars with full bellies.  :)

Could a Mars pole-vaulter set a new record? Not in a space suit. (smiley)

Offline BSenna

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Re: MCT Speculation and Discussion Thread 4
« Reply #1491 on: 01/28/2016 12:39 AM »
Here's the way I see the Depot working:

The first half dozen or so trips to Mars will carry cargo to set up habitats, ISRU machinery, and remote-contolled equipment. These preliminary forays will prepare a base for humans who will arrive later. A cargo MCT launching from Earth will be heavily loaded; it will use up essentially all its fuel just to get to the depot in orbit. It will require a refill before proceeding any further.
 
We will have a tanker variant of MCT, which has the same basic outer shell as a cargo or passenger version, but will be hollowed out as a big fuel carrier. The volume that would otherwise be cargo volume will be devoted to big fuel tanks. This could be just an expansion of the the main tanks that extend into the the cargo space. Its principle function will be to haul fuel from Earth to the depot, probably about 250 tonnes of CH4 and LOX in each trip. . Three or four loads of fuel must be transferred to the cargo-MCT before it can proceed to Mars.

We could just make a series of trips to the waiting cargo ship and sequentially fill it up. But having a depot allows us to fill up multiple cargo ships and launch as a fleet to Mars. This is the stated intent of SpaceX.

So tanker #1 arrives at the depot and docks at a berth. Tanker #2 arrives at the depot and transfers its fuel load to tanker #1, reserving just enough fuel to return to Earth via propulsive landing. These tankers are highly reusable and require little maintenance between flights, like an airplane. Tanker #2 refills at the launch site and launches again to the depot. It again transfers its fuel load to tanker #1 and returns to the launch site. Now tanker # 1 has enough fuel in its tanks to service one cargo MCT. And because we have six berths at the depot, we can perform this procedure three times simultaneously using six tanker MCTs.

Now three cargo ships arrive at the depot and dock beside three refilled tankers. The tankers transfer their fuel loads to the cargo ships and return to Earth.

We have three cargo carriers ready to trek to Mars with full bellies.  :)

Undesrtood!
« Last Edit: 06/11/2016 04:38 AM by Lar »

Offline Ionmars

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Re: MCT Speculation and Discussion Thread 4
« Reply #1492 on: 01/28/2016 08:39 AM »
Blah,, blah... blah
...
...

Undesrtood!
If you were to do a 3D model of the Depot it would just be a 2D (x,y) skeletal frame that is repeated into the third (z) dimension. Below is a sketch of the forward frame for one berth. The small circle is a "pad" for connecting to the nose of the MCT and the large circle is an imaginary volume representing one berth where one MCT is docked. The frames are connected by beams of a certain length in the z dimension. Then this 3D image is duplicated side-by-side to the right to make 5 additional berths until they join on the left side of the first berth. Voila!
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Offline Stardhingy

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Re: MCT Speculation and Discussion Thread 4
« Reply #1493 on: 01/28/2016 05:54 PM »

We will have a tanker variant of MCT, which has the same basic outer shell as a cargo or passenger version, but will be hollowed out as a big fuel carrier. The volume that would otherwise be cargo volume will be devoted to big fuel tanks. This could be just an expansion of the the main tanks that extend into the the cargo space. Its principle function will be to haul fuel from Earth to the depot, probably about 250 tonnes of CH4 and LOX in each trip. . Three or four loads of fuel must be transferred to the cargo-MCT before it can proceed to Mars.


Cargo density is far lower than fuel density,  so either the tanker is smaller or it has a lot of unused cargo volume.

I don't understand why you would need a depot though. Why not just have the tanker dock with the MCT and transfer propellent?

Offline RocketmanUS

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Re: MCT Speculation and Discussion Thread 4
« Reply #1494 on: 01/28/2016 06:03 PM »

We will have a tanker variant of MCT, which has the same basic outer shell as a cargo or passenger version, but will be hollowed out as a big fuel carrier. The volume that would otherwise be cargo volume will be devoted to big fuel tanks. This could be just an expansion of the the main tanks that extend into the the cargo space. Its principle function will be to haul fuel from Earth to the depot, probably about 250 tonnes of CH4 and LOX in each trip. . Three or four loads of fuel must be transferred to the cargo-MCT before it can proceed to Mars.


Cargo density is far lower than fuel density,  so either the tanker is smaller or it has a lot of unused cargo volume.

I don't understand why you would need a depot though. Why not just have the tanker dock with the MCT and transfer propellent?
TMI burn window. Need time to get the propellants and MCT in orbit before the window opens. Depot would be designed to store the propellants over a long period of time and could be used by other in space craft.

Launch cargo or crew MCT's to depot, fuel, then TMI burn.

With all the propellant in space before the TMI window opens up the MCT's to MArs just need to be launched and refueled at the depot. No waiting around for the propellants and no taking up launches for propellants in the TMI window.

Offline guckyfan

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Re: MCT Speculation and Discussion Thread 4
« Reply #1495 on: 01/28/2016 07:32 PM »
At some launch rate depots will make sense. They make it possible to have a steady launch sequence for tankers throughout the whole period between launch windows.

10 or maybe 20 launches can be done without depots.10 MCT will need a total number of 40 to 50 launches in ~25 weeks. That's only two per week. The numbers are quite arbitrary. Launching cargo MCT and starting to fuel them up might start early. There can be more launches a week. In that case more launches are possible without depots. The thousands of launches anticipated by Elon Musk would certainly need depots for efficiency.

Offline nadreck

Re: MCT Speculation and Discussion Thread 4
« Reply #1496 on: 01/28/2016 07:52 PM »
Another reason for a depot is to reduce risk in a way that might be specifically applicable to manned launches. This would actually be most important during the first few synods with manned flights.  I think it is safe to assume that for the first manned mission using the BFS that two BFS would be launched as simultaneously as possible and rendezvous very shortly after TMI to provide redundancy in ECLSS, and all other systems, and provide for alternative means of ensuring evacuation from the moment of rendezvous until another expedition with manned craft and supplies lands on Mars near them.  Along with the first two manned craft there might be support craft that were deemed important enough to be synchronized on the same path.  Obviously the bulk of cargo going to the first synod will probably be launched before the manned craft with only the most critical going on a route that gets them there as/more quickly as /than the manned craft.

For the craft that rendezvous or at least fly in close formation throughout the journey to Mars, you also reduce the risks to that effort by having ALL the fuel those specific craft need on orbit before you launch those craft.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline BSenna

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Re: MCT Speculation and Discussion Thread 4
« Reply #1497 on: 01/28/2016 09:40 PM »
Blah,, blah... blah
...
...

Undesrtood!
If you were to do a 3D model of the Depot it would just be a 2D (x,y) skeletal frame that is repeated into the third (z) dimension. Below is a sketch of the forward frame for one berth. The small circle is a "pad" for connecting to the nose of the MCT and the large circle is an imaginary volume representing one berth where one MCT is docked. The frames are connected by beams of a certain length in the z dimension. Then this 3D image is duplicated side-by-side to the right to make 5 additional berths until they join on the left side of the first berth. Voila!

Is this?

http://imgur.com/a/KJRna

Offline Ionmars

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Re: MCT Speculation and Discussion Thread 4
« Reply #1498 on: 01/29/2016 01:16 AM »
Pick me up from the floor! Don't tell me you created all those images since my last post. It looks spot on.  :)  :)  :)

Edit: People in my generation will understand "Tinker-Toys" and that is exactly what the framework looks like.
« Last Edit: 01/29/2016 01:24 AM by Ionmars »
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Offline raketa

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Re: MCT Speculation and Discussion Thread 4
« Reply #1499 on: 01/29/2016 04:48 AM »
I think after several cargo mission, first with FH and then MCT. When MCT successfully land on Mars. First crew will arrive without specified return day. There task will be prepare infrastructure and ask for additional resources in  preparation of infrastructure for return trip. Setup ice collection and build and maintain devices to create fuel,build tank for fuel. At the moment finishing task and prepare rocket  for return trip some of the crew will start their trip back to Earth. I think when first crew will arrive there  will be not enough fuel to bring them back, they have to build their "return ticket".

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