SpaceX News

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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kunkmiester
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Re: SpaceX News

Post by kunkmiester »

I'm not finding anything on lunar payload mass. I remember reading somewhere it was similar to gto, is that right? I know it's less than leo, but more than Mars.

It also sounds like the Roadster was put in it's trajectory from just the two stages? Makes me think you would get some mass efficiency by designing a lander incorporating it, so a cargo lander would use the second stage engine to land. Not sure if that would really boost payload, but I'm wondering, if you had a rover load, say construction equipment, doing it like this how much payload would you actually have? Particularly using a raptor engine.

I'm figuring a heavy could deliver at least a dozen construction rovers at least to the moon, so if you can keep mass and cost under control, while my original numbers were pretty crazy, you should still be able to do it for much less.

The other issue is regulation, I just realized the FAA/NASA is probably going to do something stupid like insist on a palletized/containerized rover be 100%certified even if it can't have any effect on the launch.
Evil is evil, no matter how small

krenshala
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Re: SpaceX News

Post by krenshala »

kunkmiester wrote:It also sounds like the Roadster was put in it's trajectory from just the two stages?
Yes. The second stage did a burn about six hours after launch to push the roadster into a larger heliocentric orbit. The target was to put the apoapsis at Mars orbit, but with the fuel it had it ended up reaching beyond there into the belt (not quite to Ceres orbit).
kunkmiester wrote:I'm not finding anything on lunar payload mass. I remember reading somewhere it was similar to gto, is that right? I know it's less than leo, but more than Mars.

... I'm figuring a heavy could deliver at least a dozen construction rovers at least to the moon, so if you can keep mass and cost under control, while my original numbers were pretty crazy, you should still be able to do it for much less.
Δv needed to reach your destination never changes (well, other than by the path you decide to take; e.g., Hohman Transfer takes less than a direct burn).

For geo-synchronous Earth orbit, you need ~9.4km/s (surface to LEO) + ~2.44km/s for the GTO burn + ~1.47km/s to acheive geo-synch orbit. Thats ~13.31km/s (one way) from launch to GEO. For landing on Luna, you need ~9.4km/s + ~3.12km/s for TLI + ~0.82km/s for lunar capture/low-orbit insertion, for ~13.34km/s to reach low-lunar orbit. It takes another ~1.73km/s to land on from low-lunar orbit. So, for the same Δv to reach GEO, you can reach a lunar orbit just a bit higher than 100km (what the chart I'm using has for "low lunar orbit").

For Mars, its ~9.4km/s to LEO + ~3.6km/s for Mars-Transfer + ~5.71km/s for Mars capture and reach low orbit (~200km). Some, possibly a significant amount, of that ~5.7km/s can be done with aerobraking at Mars instead of fuel usage -- depends on how you design the ship. Once at low Mars orbit, its another ~3.8km/s to land. Total Δv requirement Earth-to-Mars surface-to-surface: ~22.51km/s (not counting aerobraking savings on arrival). Plane changes due to inclination will add some to that, but not that much compared to the rest, down to a possible zero m/s added if you time your trip right (depart at the relative ascending or descending node and burn into the correct inclination).

How much payload you get depends on how much mass in the second stage needs to be used for fuel (talking about FH, here). The SpaceX website lists 26.7 metric tons to GTO (so some of that is fuel to achieve geo-synch orbit once at the correct altitude), and 63.8 metric tons to LEO. Plugging the mass differences between the two should give you the Δv of the second stage. Its probably at least 20 metric tons of payload to the lunar surface.

Skipjack
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Re: SpaceX News

Post by Skipjack »

Another boring launch. That is now number 50...

ladajo
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Re: SpaceX News

Post by ladajo »

I haven't seen any pics, however I bet it was pretty. Too bad they couldn't get the barge out for recovery. Report I saw said the landing zone was forecasted for 26-28 foot seas. That could've been cool. Fair enough, I always enjoyed a good storm at sea over the years... so maybe I am biased. :)
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
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paperburn1
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Re: SpaceX News

Post by paperburn1 »

I liked storms as well, mainly because it terrified and thrilled me at the same time. (Cue obligatory sea story) There I was standing watch with my parrot strapped to my shoulder by ten feet of flight line when I spied though my watch glass a white whale, yes that white whale, my neminess... ...and that's how I got this tattoo :lol: :lol:
I am not a nuclear physicist, but play one on the internet.

Maui
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Re: SpaceX News

Post by Maui »

Skipjack wrote:Another boring launch. That is now number 50...
I was just noticing they have 5 (!) lined up for April. Looks like they're trying hard to have the next 50 done in a year.

paperburn1
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Re: SpaceX News

Post by paperburn1 »

This could be a game changer.
http://www.newsweek.com/air-molecules-t ... tes-834320
Using air as a propellant
I am not a nuclear physicist, but play one on the internet.

Skipjack
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Re: SpaceX News

Post by Skipjack »

Maui wrote:
Skipjack wrote:Another boring launch. That is now number 50...
I was just noticing they have 5 (!) lined up for April. Looks like they're trying hard to have the next 50 done in a year.
I believe Shotwell said they are trying to have 30 launches this year. At 60 million a launch, they will have 1.8 billion is turnover this year.
Of course profits will be lower, but I assume still somewhere around one billion, maybe even better with block 5 and fairing reuse. Not bad!
The real big profits will come with their internet constellation, though. Of course that will almost require BFR/BFS, at least for the second stage of the constellation. Launching thousands of satellites (small as they may be) with FH and F9 alone does not sound practical.

Skipjack
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Re: SpaceX News

Post by Skipjack »

paperburn1 wrote:This could be a game changer.
http://www.newsweek.com/air-molecules-t ... tes-834320
Using air as a propellant
Not the only electric propulsion system that can do that. MSNW's ELF could do that years ago.

paperburn1
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Re: SpaceX News

Post by paperburn1 »

I am not a nuclear physicist, but play one on the internet.

Skipjack
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Re: SpaceX News

Post by Skipjack »

Yeah, they are throwing away older model cores now, because they don't have room to store them anymore. A nice problem to have, I guess ;)

ladajo
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Re: SpaceX News

Post by ladajo »

As I wait to wait today's launch of CRS-14, I am wondering why they are not recovering the recycle flights to pick apart for use stresses of multiple flights. It would seem to be a potential wealth of knowledge they could carry forward regarding engineering and material costs.

Standing by for another "yawn". :)

Although, this one is a push of a pre-flown Dragon & Booster, a first I think. A fully recycled mission.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

ladajo
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Re: SpaceX News

Post by ladajo »

And... Yawn...
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

Maui
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Re: SpaceX News

Post by Maui »

ladajo wrote:As I wait to wait today's launch of CRS-14, I am wondering why they are not recovering the recycle flights to pick apart for use stresses of multiple flights. It would seem to be a potential wealth of knowledge they could carry forward regarding engineering and material costs.
I was thinking the same thing. I wonder if there’s basically two categories of parts: ones that show any kind of measurable wear, and those that don’t. Maybe after so many cores (including some that have been recovered twice) that there’s not any good reason to think there will be wear they haven’t already seen.

paperburn1
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Re: SpaceX News

Post by paperburn1 »

It is my understanding that Block 3 and Block 4 was only intended to fly twice and data beyond that point was not nearly as valuable as the data they are getting for the "edge of the Flight profile" landing they are getting from this testing and performance evaluation.


EDIT : Hint 3 engines is all it would take to land a BFR. Edge of flight profiles with Falcon use three engines, you do the math.
I am not a nuclear physicist, but play one on the internet.

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