Skylon

SpaceX Discussion Thread

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7 minutes ago, DunnoAnyThing said:

BTW any chance anyone in this forum *might* get a ride?

(Just a wish, you know)

There's a chance. Just not a very good one.

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11 minutes ago, DunnoAnyThing said:

BTW any chance anyone in this forum *might* get a ride?

(Just a wish, you know)

am a musician and have written about the Moon...

Still, with no spaceship completed and no guarantee that this system will even work in flight, at this point I'm skeptical to sign up for this particular flight. I think I would prefer to fly on a later mission, one where I am building and learning things for people to use and build upon in the far future, rather than one where my mission is simply to get people excited about space in the present. 

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Given that we are space geeks and are generally creative, and come from non-poor countries, most of us are probably in the top 0.1% of the people considered for this mission. If only a quarter of that top 0.1% want to go, that's still about 2 million people. There are eight available seats, so any one of us has a 1 in 250,000 chance of making it in. There are about 300 users online right now, and assuming that 3 times that are active but 1/3 are candidates, that's a 300/250,000 chance for a forumer to be on the mission is 1 in 833, or about 0.1%.

And 0.1% is waaaaaay better than no chance, although I wouldn't bet on it.

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I wont be surprised if elon builds a medium f rocket before the big f***ing rocket. The tech has simply not be tested yet.

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On 14 September 2018 at 10:42 AM, sh1pman said:

It's on their official twitter though. Previously their artist renderings were accurate.

Here's a TLDR of my thoughts: I like the new design, I don't like that they changed the design while the first one is already under construction.

On 14 September 2018 at 12:28 PM, RedKraken said:

And where are the landing gear? in the fins? back to 3 again?

I think the fins ARE the landing gear.

 

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Just now, ChrisSpace said:

Here's a TLDR of my thoughts: I like the new design, I don't like that they changed the design while the first one is already under construction.

Not a big deal, a tank is a tank. The  changes only change what gets attached to the tank. Besides, it’s presumably the BFGrasshopper tank

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Umm, I just re-watched the presentation and...

First of all, payload capacity has dropped from 150 to 100 metric tons. I really hope the cost will scale down too.

Second, the travel time to the moon is just... two days? How much extra Dv is that taking up compared to a normal 4-ish day travel time?

Third, who's going to update wikipedia?

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20 minutes ago, ChrisSpace said:

Umm, I just re-watched the presentation and...

First of all, payload capacity has dropped from 150 to 100 metric tons. I really hope the cost will scale down too.

Second, the travel time to the moon is just... two days? How much extra Dv is that taking up compared to a normal 4-ish day travel time?

Third, who's going to update wikipedia?

Apollo 8 reached peri-Mün 69 hours into the mission, including time in a parking orbit, sounds about right.

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19 minutes ago, ChrisSpace said:

Umm, I just re-watched the presentation and...

First of all, payload capacity has dropped from 150 to 100 metric tons. I really hope the cost will scale down too.

Second, the travel time to the moon is just... two days? How much extra Dv is that taking up compared to a normal 4-ish day travel time?

Third, who's going to update wikipedia?

1. This is probably mostly because of the lack of vacuum raptors, we might see the payload jump back up on Block II or if the engines are changed again. Since it's effectively the same rocket but with less efficient nozzles I don't expect cost to scale down. Also these numbers may have been for the crew version (and the cabin has been extended). We have yet to see numbers for the updated cargo and tanker variants.

2. Apollo made it in ~3 according to random googling, 2 shouldn't be that difficult, a small increase in Delta-V at the start of the burn can decrease the travel time non linearly since the top of the orbit takes the most time, and by encountering the moon before the top you're effectively eliminating the top. Ish. An extreme example of time reduction is New Horizons which passed the Moon's orbit in <9 hours although this will obviously not be the same profile any standard lunar mission would take. In short, not much extra Delta-V. If I remember I could do some tests in RSS tomorrow.

3. Not me!

54 minutes ago, ChrisSpace said:

Here's a TLDR of my thoughts: I like the new design, I don't like that they changed the design while the first one is already under construction.

I think the fins ARE the landing gear.

 

I believe the gear extends from the fins, but you may be right.

56 minutes ago, Xd the great said:

I wont be surprised if elon builds a medium f rocket before the big f***ing rocket. The tech has simply not be tested yet.

I doubt it. This is already the MFR, down from the 12m ITS. A separate version at this point would probably not have a huge advantage IMO.

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22 minutes ago, Ultimate Steve said:

1. This is probably mostly because of the lack of vacuum raptors, we might see the payload jump back up on Block II or if the engines are changed again. Since it's effectively the same rocket but with less efficient nozzles I don't expect cost to scale down. Also these numbers may have been for the crew version (and the cabin has been extended). We have yet to see numbers for the updated cargo and tanker variants.

2. Apollo made it in ~3 according to random googling, 2 shouldn't be that difficult, a small increase in Delta-V at the start of the burn can decrease the travel time non linearly since the top of the orbit takes the most time, and by encountering the moon before the top you're effectively eliminating the top. Ish. An extreme example of time reduction is New Horizons which passed the Moon's orbit in <9 hours although this will obviously not be the same profile any standard lunar mission would take. In short, not much extra Delta-V. If I remember I could do some tests in RSS tomorrow.

3. Not me!

I believe the gear extends from the fins, but you may be right.

I doubt it. This is already the MFR, down from the 12m ITS. A separate version at this point would probably not have a huge advantage IMO.

The manned version would want more surface engines as its also the abort system. 
They can drop the rear cargo compartments and add vacuum engines who makes sense for the cargo missions and the refueling ones. you can also make the mars ship different from the manned orbital one. 

Its pretty cheap to reduce travel time over the minimum cost one, tend to do it going to Minmus there reducing it from 9 to 4 days cost less than 200 m/s including the orbital injection who is the expensive part, with an free return trajectory its cheaper. 
 

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1 hour ago, Ultimate Steve said:

We have yet to see numbers for the updated cargo and tanker variants.

...and we don't know anything about those yet, I suppose.

1 hour ago, CatastrophicFailure said:

Apollo 8 reached peri-Mün 69 hours into the mission, including time in a parking orbit, sounds about right.

This is still two-thirds of that, so I don't see why it's worth the inefficiency.

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1 hour ago, ChrisSpace said:

First of all, payload capacity has dropped from 150 to 100 metric tons. I really hope the cost will scale down too.

The reduction was addressed in the answer to the question regarding the use of SL engines.

This reduces the payload because of lower Isp.

It sounded like that number could go up via replacing a few of the bottom cargo pods with vac Raptors.

As Musk said, this allows a simple upgrade path for the vehicle.

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I find it interesting to compare the BFS capabilities with a 747 freighter. They are close enough to be somewhat comparable:

  • 747-8F - 137 metric tons, 858 m^3 cargo volume
  • 747-Dreamlifter - 113 metric tons, 1840 m^3 cargo volume
  • BFS - 100 metric tons, 1000 m^3 cargo/crew volume

It sort of puts the vehicle in perspective for me even if we are comparing aircraft to spacecraft.

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44 minutes ago, ChrisSpace said:

This is still two-thirds of that, so I don't see why it's worth the inefficiency.

You're trading fuel for consumables (water, O2, food, etc), also they mentioned "skimming the moon then going way far away (above both moon and earth)," some free returns do just this, one of the mission plans for Orion, IIRC. Like Musk said, the mission plan isn't even close to being finalized at this point, so that's all subject to change.

 

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2 hours ago, satnet said:
  • 747-8F - 137 metric tons, 858 m^3 cargo volume
  • 747-Dreamlifter - 113 metric tons, 1840 m^3 cargo volume
  • BFS - 100 metric tons, 1000 m^3 cargo/crew volume

2 heavy battle tanks.

2 sperm whales or 2/3 of a blue whale.

Edited by kerbiloid
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New BFS looks like a dolphin 

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The press conference was disappointingly light on technical details.  But that was probably to be expected from a briefing aimed at the mainstream press.  Hopefully more details will be released soon.

Edited by AVaughan
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1 hour ago, Jaff said:

New BFS looks like a dolphin 

Yeah, they are preparing to leave earth.

Thanks for all the fish :-)

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2 minutes ago, Green Baron said:

Thanks for all the fish :-)

So I can have all the fish then !

... for 2 days...

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8 hours ago, DunnoAnyThing said:

BTW any chance anyone in this forum *might* get a ride?

(Just a wish, you know)

Well, Scott Manley's a DJ, Everyday Astronaut's a photographer, and Matt Lowne is a filmmaker (sort of)- I say we stand a pretty good chance!

(Though with all three of them on board, I worry they'll coordinate a landing- they definitely have the skill!)

Edited by Ho Lam Kerman
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1 hour ago, Ho Lam Kerman said:

Well, Scott Manley's a DJ, Everyday Astronaut's a photographer, and Matt Lowne is a filmmaker (sort of)- I say we stand a pretty good chance!

(Though with all three of them on board, I worry they'll coordinate a landing- they definitely have the skill!)

They wont coordinate a landing on the moon. They will fly to Mars, land and refuel using chemistry and come back after years. 

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