SpaceX News

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

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Diogenes
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Re: SpaceX News

Postby Diogenes » Tue Sep 18, 2018 9:14 pm

‘What all the wise men promised has not happened, and what all the damned fools said would happen has come to pass.’
— Lord Melbourne —

Skipjack
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Re: SpaceX News

Postby Skipjack » Tue Sep 18, 2018 10:22 pm

It is not just aesthetics. The new design has a much larger leg span, which means that the rocket will be more stable when landed on unprepared ground. The new design also increases the ground clearance a lot. That helps prevent damage from debris. The aesthetics part comes in for the 3rd "leg", which indeed just looks better that way. Probably made little difference in dry mass compared to other possible shapes with the same leg span.

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Re: SpaceX News

Postby Maui » Tue Sep 18, 2018 11:55 pm

Did the previous designs actually address legs? My recollection is that there was talk that it would "snap into" docking connector on the pad on Earth. I think it may have been glossed over how legs would work without such a pad/dock available. Based on yesterday's info from Musk, it sounds like they previously planned on having significantly sized legs that weren't part of the renders.

EDIT: I guess I was wrong about that:
Image

EDIT2: ...but in the context of the Q&A, I thought Musk made it pretty clear that all fins were added primarily for aesthetics. Clearly they could have made any separate legs as big as needed for stability without coupling them with fins. His answer seemed to concede as much.

TDPerk
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Re: SpaceX News

Postby TDPerk » Wed Sep 19, 2018 12:08 am

molon labe
montani semper liberi
para fides paternae patria

Maui
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Re: SpaceX News

Postby Maui » Wed Sep 19, 2018 2:15 am

Perk, the question was why further design changes were made, and Musk's response was to describe why fins were added (for aesthetics). He said that added risk, but did not go on to describe how that design might reduce risk in any other way. The only part where reduced risk was mentioned was in regard to the new engine config which allows for multi-engine loss contingencies.

Perhaps what you say about de-complicating aeroshell is true, but as far as I am aware, Musk did not make that point. I assume that's conjecture on your part? While I don't know that I buy that conjecture (loss of function of fin during re-entry would doom landing) Slipjack has conjecture about increased clearance that I do buy. Still, fins would not be needed for increased leg length, only longer legs.

Giorgio
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Re: SpaceX News

Postby Giorgio » Wed Sep 19, 2018 10:23 am

A society of dogmas is a dead society.

Skipjack
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Re: SpaceX News

Postby Skipjack » Wed Sep 19, 2018 6:13 pm


Giorgio
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Re: SpaceX News

Postby Giorgio » Thu Sep 20, 2018 10:25 am

A society of dogmas is a dead society.

TDPerk
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Re: SpaceX News

Postby TDPerk » Thu Sep 20, 2018 1:41 pm

Also the fins have the depth to house a truss carrying the load of the now vertically deployed legs to the fuselage, although carbon fiber has such a high stiffness it may be incorporated into the skin of the fins instead of being a frank truss structure. Can you imagine the complication of hanging trusswork into a hypersonic airstream? Which the use of fins entirely avoids.

Bottom line is, in mentally inserting the word "overall" in front of "risk", Maui is in danger of having contracted pathological skepticism.

He shouldn't do that.

No one should.
molon labe

montani semper liberi

para fides paternae patria

Maui
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Re: SpaceX News

Postby Maui » Fri Sep 21, 2018 5:54 pm

Pathological skepticism is great! I think everyone could use more skepticism.

I am comforted that you all are not concerned by this design change, though no one has really addressed how such a large surface area can be reliably/safely actuated at hypersonic speeds.

As an aside, why would separate legs mean hanging trusswork? Existing F9 extendable legs would certainly be the better model if separate legs were to be used, yes?

paperburn1
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Re: SpaceX News

Postby paperburn1 » Fri Sep 21, 2018 6:27 pm

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

Giorgio
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Re: SpaceX News

Postby Giorgio » Fri Sep 21, 2018 8:05 pm

A society of dogmas is a dead society.

Skipjack
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Re: SpaceX News

Postby Skipjack » Fri Sep 21, 2018 9:23 pm


TDPerk
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Re: SpaceX News

Postby TDPerk » Sat Sep 22, 2018 2:43 am

molon labe

montani semper liberi

para fides paternae patria

Giorgio
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Re: SpaceX News

Postby Giorgio » Sat Sep 22, 2018 9:29 am

A society of dogmas is a dead society.


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