Author Topic: MCT Speculation and Discussion Thread 4  (Read 611001 times)

Offline malu5531

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Re: MCT Speculation and Discussion Thread 4
« Reply #2940 on: 09/27/2016 11:33 PM »
I guessed 36 engines, did not see anybody guessing more, so if we use The Price Is Right rules....

Matthew

My guess was 46

Online matthewkantar

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Re: MCT Speculation and Discussion Thread 4
« Reply #2941 on: 09/27/2016 11:41 PM »
I guessed 36 engines, did not see anybody guessing more, so if we use The Price Is Right rules....

Matthew

My guess was 46

Must have missed that. Are you familiar with The Price Is Right over there in Sweden?

Matthew

Offline Impaler

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Re: MCT Speculation and Discussion Thread 4
« Reply #2942 on: 09/28/2016 12:03 AM »
I grew up watching the Price is Right, it's an American produced show or at least my version was, did you have a locally produced version in Sweden as it seems that you would have to use local prices and currency for the audience to be able to have a sense of the prices.  On the other hand if I could watch the show at 8 years old with no idea what anything costs then I guess it could be watched internationally so long as it was dubbed.

Still I'm inclined to give malu5531 the engine count trophy via being only 4 engines off rather then 6 engines off, I think the default assumption is closest with both over and under being equal rather then Price is Right rules as GORDAP didn't specify any rules.

Offline malu5531

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Re: MCT Speculation and Discussion Thread 4
« Reply #2943 on: 09/28/2016 12:13 AM »
I guessed 36 engines, did not see anybody guessing more, so if we use The Price Is Right rules....

Matthew

My guess was 46

Must have missed that. Are you familiar with The Price Is Right over there in Sweden?


I'm sorry, I'm not familiar with that.

I also did quite good on S1 thrust:


My best guess

4 - 120 MN SL thrust


Actual was 127.8 MN SL thrust

Offline malu5531

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Re: MCT Speculation and Discussion Thread 4
« Reply #2944 on: 09/28/2016 12:20 AM »
For those with L2, my guess was based on these calculations I did a while ago, with the goal of figuring out what design it would take to build an MCT according to rumoured specs at that time.

Offline CJ

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Re: MCT Speculation and Discussion Thread 4
« Reply #2945 on: 09/28/2016 01:02 AM »
I'm thrilled by the Musk presentation. However, I'm worried by what I didn't see.

Two MCT concerns in particular I have; heat and power. How, exactly, will they preserve the subcooled LOX and methane needed for landing during interplanetary cruise (80 to 115 days)? And also, how will they handle the heat generated on MCT by the 100 people aboard, plus life support, plus lighting, etc? On ISS, cooling is very complex, and if I'm remembering correctly, the cooling system (ammonia based) outmasses the solar arrays.

Also, regarding solar arrays for power... what we see in the demo looks like an area on par with the ISS arrays, so how does one get sufficient power from that area to handle life support, etc, for 100 people? And that's without considering the diminished sunlight at Mars.

One guess I have regarding mass fractions, etc, is that refueling won't be done in LEO, but in an elliptical orbit - lower delta/v needed for the TMI burn that way, thus reducing the mass fraction issue. 


Offline Lars-J

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Re: MCT Speculation and Discussion Thread 4
« Reply #2946 on: 09/28/2016 01:09 AM »
I'm thrilled by the Musk presentation. However, I'm worried by what I didn't see.

Two MCT concerns in particular I have; heat and power. How, exactly, will they preserve the subcooled LOX and methane needed for landing during interplanetary cruise (80 to 115 days)? And also, how will they handle the heat generated on MCT by the 100 people aboard, plus life support, plus lighting, etc? On ISS, cooling is very complex, and if I'm remembering correctly, the cooling system (ammonia based) outmasses the solar arrays.

Also, regarding solar arrays for power... what we see in the demo looks like an area on par with the ISS arrays, so how does one get sufficient power from that area to handle life support, etc, for 100 people? And that's without considering the diminished sunlight at Mars.

One guess I have regarding mass fractions, etc, is that refueling won't be done in LEO, but in an elliptical orbit - lower delta/v needed for the TMI burn that way, thus reducing the mass fraction issue.

If you expected *that* level of engineering detail, you were never going to be satisfied.

Offline envy887

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Re: MCT Speculation and Discussion Thread 4
« Reply #2947 on: 09/28/2016 01:12 AM »
...
One guess I have regarding mass fractions, etc, is that refueling won't be done in LEO, but in an elliptical orbit - lower delta/v needed for the TMI burn that way, thus reducing the mass fraction issue.

What mass fraction issue? The number quoted was 450 tonnes to the Mars surface, assuming LEO transfer. The mass fraction through TMI appears to be no issue at all.

Online launchwatcher

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Re: MCT Speculation and Discussion Thread 4
« Reply #2948 on: 09/28/2016 02:04 AM »
Must have missed that. Are you familiar with The Price Is Right over there in Sweden?
I'm sorry, I'm not familiar with that.
The phrase used on the show was "closest without going over" (in other words, the largest guess which is equal to or below the target value).

Offline Lar

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Re: MCT Speculation and Discussion Thread 4
« Reply #2949 on: 09/28/2016 02:37 AM »
Might be fun for folks to go back and edit their prediction lists to show how they did (me? not that great)
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline envy887

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Re: MCT Speculation and Discussion Thread 4
« Reply #2950 on: 09/28/2016 02:45 AM »
My prediction was almost exactly half the size and performance, I thought the 15 mlfb designs were oversized. 8)

I did correctly predict that the Raptor vacuum nozzle would be under 4m in diameter though (it's 3.85).

Offline ZachF

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Re: MCT Speculation and Discussion Thread 4
« Reply #2951 on: 09/28/2016 03:03 AM »
Here is my rough MSPaint size comparison between the ICT and some space stations/craft.

Offline Stan-1967

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Re: MCT Speculation and Discussion Thread 4
« Reply #2952 on: 09/28/2016 03:21 AM »
Here is my rough MSPaint size comparison between the ICT and some space stations/craft.

Can you do the IST/MCT sitting on the deck of the ASDS?   :o

Offline envy887

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Re: MCT Speculation and Discussion Thread 4
« Reply #2953 on: 09/28/2016 03:27 AM »
Here is my rough MSPaint size comparison between the ICT and some space stations/craft.

Can you do the IST/MCT sitting on the deck of the ASDS?   :o

Footprint should be just about as big as the F9 S1.

Offline Lars-J

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Re: MCT Speculation and Discussion Thread 4
« Reply #2954 on: 09/28/2016 03:44 AM »
Might be fun for folks to go back and edit their prediction lists to show how they did (me? not that great)

I don't know if I ever made real "prediction checkbox list", but I have made several posts with the following predictions that came true:
 - spacecraft as integrated 2nd stage
 - biconic/side entry
 - powered by multiple raptors instead of a single one (although I was off on the count, I expected 5)
 - no launch abort capsule (abort the whole thing)

The booster was roughly what I expected, but bigger and lacking landing gear.

Offline watermod

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Re: MCT Speculation and Discussion Thread 4
« Reply #2955 on: 09/28/2016 04:08 AM »
I would like to see the first ITS going to MARs with both a ground side fuel/oxidizer plant, 10 or 12 GPS stats and a large number of Elon's internet communications sats.   (Just like those in the planned 4000 node system for Earth) A few observation sats like Digital Globe uses too would be nice in the payload.
That way when the actual astronauts and colonists come there would be fuel, communication, accurate ground positioning and accurate imaging that could be down loaded to folks on Mars or provided to those orbiting Mars.

Another nice addition on another craft would be a nice sized spaced power system to broadcast power to the colony site on the ground.   If not that then a large mylar film mirror to concentrate sunlight for the ground based solar system.   It could provide localized heating for melting ice too.

Offline Ludus

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Re: MCT Speculation and Discussion Thread 4
« Reply #2956 on: 09/28/2016 04:21 AM »
Any idea how cargo gets loaded/unloaded?

If it's going to deliver 450T of cargo some of it will have to be loaded in orbit just like it has to take on propellant, that's a lot more than it can take to NEO reusable.

I'm curious about the pure cargo variant which I'd assume would have big bay doors a bit like the shuttle.
I'd expect more to be built of that than either the Heart of Gold class or the Tanker based on the notions that there will be 10X the need for cargo over passengers and a Tanker has such a fast potential turn around by comparison that you don't need too many.
« Last Edit: 09/28/2016 04:25 AM by Ludus »

Offline Helodriver

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Re: MCT Speculation and Discussion Thread 4
« Reply #2957 on: 09/28/2016 04:22 AM »
My one BFR speculation was dead on.  Helodriver predicts the future (again)   ;)



A good look at those enormous rainbirds in that photo. Assuming the yellow railing is 4' high, I get a quick-and dirty estimate of the rainbirds at 57'. :o That seems ridiculously big.

Could they be backed off from the rocket far enough that that actually makes sense? Or am I way off on the height?

Pure speculation - These are  oversized for an F9 family vehicle but are right sized for a larger follow on vehicle. 39A is the eventual BFR launch site.

Offline Impaler

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Re: MCT Speculation and Discussion Thread 4
« Reply #2958 on: 09/28/2016 04:31 AM »
Might be fun for folks to go back and edit their prediction lists to show how they did (me? not that great)

I don't know if I ever made real "prediction checkbox list", but I have made several posts with the following predictions that came true:
 - spacecraft as integrated 2nd stage
 - biconic/side entry
 - powered by multiple raptors instead of a single one (although I was off on the count, I expected 5)
 - no launch abort capsule (abort the whole thing)

The booster was roughly what I expected, but bigger and lacking landing gear.

To be precise the BFS we were shown is cylindrical with a rounded nose and thick fins that look to hold the landing gear, not bi-conic which would involve the vehicle widening all the way down to the base, the fins can give a false sense that's whats happening but the cut-away is clear the central body is cylindrical.

That said both cylindrical and bi-conic were combined on the questionnaire and the entry profile is indeed horizontal which was the more important distinction.

Offline ZachF

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Re: MCT Speculation and Discussion Thread 4
« Reply #2959 on: 09/28/2016 04:41 AM »
The ITS concept video is pretty popular on Facebook, already has over 1m views...

(at least 15 of those are mine, lol  :D )

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