Skylon

SpaceX Discussion Thread

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2 hours ago, sh1pman said:

It’s not always possible to land a booster like SpaceX does. If you have a single powerful engine like RD-180 that can’t throttle down that deeply, or even be restarted, then recovering just the engine is your best option, still better than no reuse.

True, for the short term. But is an interim design worth it when they should be coming up with an engine, either new or existing, that is small enough to be clustered and that can be restarted (or have that capability added). Oh, and throttleable 

Or take some existing restartable large engines and cluster them under a new bigS rocket airframe *coughSLScough*

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4 minutes ago, StrandedonEarth said:

True, for the short term. But is an interim design worth it when they should be coming up with an engine, either new or existing, that is small enough to be clustered and that can be restarted (or have that capability added). Oh, and throttleable 

Or take some existing restartable large engines and cluster them under a new bigS rocket airframe *coughSLScough*

Yea, except SLS is going to use these high-tech, super expensive, restartable engines... on expendable launches. Without restarting them. This I don’t really understand. Still, I like the second option more. Bigger is always better, especially in case of rockets. Something about square-cube law, if I remember correctly.

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42 minutes ago, sh1pman said:

Yea, except SLS is going to use these high-tech, super expensive, restartable engines... on expendable launches. Without restarting them. This I don’t really understand. Still, I like the second option more. Bigger is always better, especially in case of rockets. Something about square-cube law, if I remember correctly.

AFAIK, the RS-25 is not restartable 

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3 hours ago, Ultimate Steve said:

It's official now!

xH947zb.jpg

Real crew access arms have a distinct lack of windows and unenclosed walkways.

26578523.jpg

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Shiny AND futuristic :D With entire tower refurbished the launchpad will look glorious - like a part of a proper spaceport.

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8 hours ago, StrandedonEarth said:

AFAIK, the RS-25 is not restartable 

Shuttle engines weren’t restartable? My bad then, I thought they were. How did they circularize then, with OMS?

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6 minutes ago, sh1pman said:

Shuttle engines weren’t restartable? My bad then, I thought they were. How did they circularize then, with OMS?

Yes, the RS-25 was never designed to be restarted during a mission, only after refurbishment between missions. The OMS was used for all major maneuvers after launch.

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6 hours ago, Scotius said:

Shiny AND futuristic :D With entire tower refurbished the launchpad will look glorious - like a part of a proper spaceport.

I suspect the arm to be used for bfr missions too.

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1 hour ago, Xd the great said:

I suspect the arm to be used for bfr missions too.

No.

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2 hours ago, Xd the great said:

I suspect the arm to be used for bfr missions too.

Different heights, so not unless they mount it on an elevator. It should probably be wider to be able to load/unload 100 passengers in a reasonable time 

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Spoiler
41 minutes ago, StrandedonEarth said:

load/unload 100 passengers in a reasonable time 

Inflatable traps.
SISO: "Slide in. Slide out."

 

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2 hours ago, StrandedonEarth said:

Different heights, so not unless they mount it on an elevator. It should probably be wider to be able to load/unload 100 passengers in a reasonable time 

100 pax is regional airliner size. They are typically boarded and unboarded through a single, narrow one person at a time sized door. This happens in a reasonable time thousands of times every day. That access arm will not be the limiting factor for boarding time regardless of the destination and attire (casual or space suit).

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On 8/12/2018 at 7:51 AM, sevenperforce said:

Unrelated: would a Falcon Heavy have been able to deliver Parker Solar Probe with the same performance as the DIVH last night? 

My guess is that it would have had to expend at least its core.

 

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Cool. Now... What exactly is PSP's 3rd stage C3 performance?

Edited by Wjolcz

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7 minutes ago, Wjolcz said:

Cool. Now... What exactly is PSP's 3rd stage C3 performance?

I’m a little fuzzy on the details, but C3 is basically a measurement of the available oomph from a launcher to do a thing. 

 

So, according to that chart, could an expendable FH have sent the probe on its way without the solid kick stage, then?

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17 minutes ago, Wjolcz said:

Cool. Now... What exactly is PSP's 3rd stage C3 performance?

Wiki lists the 3rd stage as a Star 48BV (V is for Vendetta Vectoring) and according to the old Orbital ATK motor catalog, that motor has 292.1s ISP, and 4774 lb and 305.5 lb loaded and burnt out weights.

...calculating...

3557 m/s

Edit:

Because I'm looking at the spec sheet and said spec sheet lists thrust, the acceleration at burn out is almost 9 g's!

Edited by Racescort666
MOAR BOOSTERS!!!!!!

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1 hour ago, Racescort666 said:

Wiki lists the 3rd stage as a Star 48BV (V is for Vendetta Vectoring) and according to the old Orbital ATK motor catalog, that motor has 292.1s ISP, and 4774 lb and 305.5 lb loaded and burnt out weights.

...calculating...

3557 m/s

Edit:

Because I'm looking at the spec sheet and said spec sheet lists thrust, the acceleration at burn out is almost 9 g's!

You included the mass of the PSP in that, right?

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12 hours ago, NSEP said:

Clever.

So with one test spaceship supposedly partially constructed, they are certain it is at least marginally possible to get people up there in 6 years. Interesting.

What I wonder is whether the first colonists will stay there for two years or four, or even more. If everybody comes home on the first transfer, the base will be empty for several months*.

*What do we use instead of "months" for Mars? It's only really a relevant time unit on Earth. Maybe they could divide the calendar year into quarters for seasons, then divide those into equal thirds cut to the nearest sol for "months". 

Anyways, I really like the big push to get lots and lots of people to Mars once this system is operational. That will really help get a permanent colony.

 

We also should be able to grow fruits and vegetables in space, and insects would be good too.

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25 minutes ago, cubinator said:

*What do we use instead of "months" for Mars? It's only really a relevant time unit on Earth. Maybe they could divide the calendar year into quarters for seasons, then divide those into equal thirds cut to the nearest sol for "months".

In Kim Stanley Robinson's Mars books, his colonists used a calendar based on the number of degrees away from Northern hemisphere equinox. They also divided the year into 24 months labeled 1Jan, 1Feb, ... 1Dec, 2Jan, ... 2Dec.

http://www.kimstanleyrobinson.info/content/martian-calendar

Edited by mikegarrison

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Just define the martian year as 668 martian days, divide into 4 167 sol seasons. The year is closer to 669 sols, but it doesn't divide as nicely, so you just need more frequent leap years. Months are almost entirely unnecessary, and seasons are only needed to make it easy to get an idea of the temperature. All farming is going to be high tech from the start, so the month-based rules of thumb on planting and growing won't be used.

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