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SpaceX Discussion Thread


Skylon

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5 hours ago, Nightside said:

would guess that the biggest difference is how much control SpaceX thinks they will have in the terminal landing phase. They may be planning on having more throttle control,which would allow for more time to correct translation. This would reduce the need for wide legs. 

Also, Superheavy will never (AFAIK) land on a drone ship, it will always return to a landing pad that’s in exactly the same place, and exactly the same height. One thing that’s made barge landings dicey is the up and down motion of the deck, even if it’s kept level. That’s a harder target to hit when you can’t hover. I would think SH would be able to hover, I don’t recall if it has a center mounted engine, but if it does it should have no trouble hovering on a single (or several) throttled Raptors. 

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On 5/3/2020 at 12:42 AM, sevenperforce said:

You still need full tank volume. dV for single-stage from LEO to the lunar surface and back again is immense.

Moonship will not return to LEO but stay in lunar orbit. It can not aerobrake for one while the tanker can aerobrake back from moon. Moonship still need land from hing moon orbit and get up again. 
However the basic version only need to do this and does not need room for 100 people and an 100 ton payload capacity. Initially crew will arrive in Orion, might use dragon 2 down the line but it will be an 4-7 man crew until Starship fly manned  missions but even then you don't send 100 on an moon landing unless majority is tourists. Nor do you need an huge payload, say 15 ton for 2-3 tesla style rover and an drill rig. The weight savings let you use shorter tanks and make this easier to refuel perhaps saving you from refueling the tanker in ecliptic orbit. 
On the other hand it can easy have falcon 9 style legs. Yes they need shock absorbers but you don't need to fold them up again once you extend them. 

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Watching this, I keep hearing the melody from a JackInTheBox in the back of my head. :/ Something maybe coming at any moment. ANY. MOMENT. Maybe something bad, maybe something good, maybe nothing at all. And the wait is just maddening. 
 

Spoiler

Kinda feels like this...

giphy.gif

I really can’t wait until this is the boring part. :P

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So if they load the propellant will they also do the static fire, or fully load, unload, load again and then static fire?

They need to fully load it anyway, but if something goes horribly wrong when it's fully loaded and firing then it will be a massive fireball. So probably do the static fire with as little prop as possible.

Edited by Wjolcz
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50 minutes ago, Wjolcz said:

So probably do the static fire with as little prop as possible.

Presumably they're taking how long they want to fire the engine for and calculating how much propellant they need for that time.

Though they probably have a bit of excess as usually rocket engines don't like burning to depletion. It does bad things to the preburners and turbopumps and whatnot.

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5 hours ago, Wjolcz said:

So if they load the propellant will they also do the static fire, or fully load, unload, load again and then static fire?

They need to fully load it anyway, but if something goes horribly wrong when it's fully loaded and firing then it will be a massive fireball. So probably do the static fire with as little prop as possible.

As long as the props don't mix before something goes wrong it will only be a deflagration. It would actually be less damaging to have fully-fueled tanks go up in flames than to have even the the autogenous pressurant gas in both tanks mix and then ignite. For the test hop they will need to fly only partly full, but I wager that for the static fire they fill-er-up, if for no other reason than to reduce stresses on whatever hold-downs they may have.

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