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Starship / Super Heavy

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Re: Starship / Super Heavy

#211

Post by dempseye »

ehnto wrote: post #200
sgt wrote: post #167

Earlier quoted context omitted.

Feet, not feets.

Not foot?

I never noticed this, but after thinking about it for a few minutes it seems that in standard usage there is a difference between attributive adjectives and predicative adjectives.

As an attributive adjective, "foot" is indeed correct, e.g. "a 130 foot yacht."

As a predicative adjective, "feet" is correct, e.g. "the yacht was 130 feet long."

Occasionally, in certain regional variations, you may hear "foot" used in the second case: "the yacht was 130 foot long."

Re: Starship / Super Heavy

#212

Post by baq »

sneak wrote: post #46
zaroth wrote: post #3

The FAA recently updated this page as part of the new Environmental Assessment at Boca Chica which is required before SpaceX can be approved for orbital flights. Their current approval is good for testing (vertical) flights of Starship and Superheavy, but does not currently permit orbital flight from Boca Chica as I understand it. They are currently in a public comment period thru Jan 22.

What's the environmental impact delta between a 12km launch and landing and an orbital launch and landing? I can't imagine the difference to the ground environment is that significant.

the noise. 30ish (28?) raptors will make a lot of it.

and if it explodes on the pad... 1kt TNT equivalent? that's a tactical nuke.

Re: Starship / Super Heavy

#213

Post by baq »

childintime wrote: post #202
zaroth wrote: post #65

Earlier quoted context omitted.

Sounds levels in particular will be extreme at launch (as in, deadly even outside the blast radius). And there's a lot more fuel that could potentially explode over populated areas on the way into orbit. For this reason, I think the intent is for Superheavy launches to be mainly done far out at sea. But Boca is needed in the interim for testing purposes.

> Sounds levels in particular will be extreme at launch (as in, deadly even outside the blast radius) Though that's generally true, Everyday Astronaut watched the SN8 launch up "close" and reported the sound was (relatively) mild. Indeed the raptors sounded differently, with less of the violent "cracking up". There may be a bit of a surprise coming here.

three engines, throttled.

the full stack will have 30ish, full throttle, perhaps even above 100% current. the sound is going to break rocks apart. i wonder what the suppression system will look like.

Re: Starship / Super Heavy

#214

Post by inglor_cz »

mabbo wrote: post #9

> The fully integrated Starship/Super Heavy launch vehicle will be approximately 400 feet tall and 30 feet in diameter. For reference, the Saturn V rocket from the Apollo program was 363 feet tall. It was 33 ft wide at the first stage, while Starship is 30 ft wide all the way to the top. It's just massive. And it's fully reusable. What a game changer.

I live on a partly forested hill that towers about 250 ft over the river valley where the railway is. When I go to the railway station and wait for a train, the hill is really dominant on the near horizon.

And whenever I realize that the full Starship + SuperHeavy stack is going to be much taller than that hill, I am just speechless. That is one big freaking rocket, one big trampoline for mankind, so to say.

Re: Starship / Super Heavy

#215

Post by Denvercoder9 »

beaner wrote: post #168
randallsquared wrote: post #132

Earlier quoted context omitted.

I believe it requires a refuel in orbit to get to the moon. So, two missions, but still super impressive.

Genuine question, how will tankers get into space? If most of the ship's size is already dedicated to fuel that's burnt, that seems to leave little left for fuel payload. I also assume fuel payload would be much heavier than other types of payload, requiring more ship fuel to launch it, further taking up space. It seems like for every full refill you could provide in space it'd take an additional 3-4 ships just to ge…

The tyranny of the rocket equation, combined with Earth's deep gravity well, and the higher efficiency of rocket engines in vacuum makes it seem much worse than it is.

E.g. for a lunar mission: it takes 9.4 km/s Δv to get to low Earth orbit (LEO), but only 5.5 km/s Δv to get from there to the Moon [1]. Raptor (the engine used on Starship) has an exhaust velocity of 3.2 km/s on Earth, and 3.7 km/s in vacuum [2]. Plugging those numbers in the rocket equation, to get to LEO you need about 19x your payload mass in fuel. However, to get from LEO to the moon surface, you only need 4x your payload mass in fuel. So while a tanker can indeed only bring a small fraction of its launch mass as fuel to orbit, once you're in orbit you don't need that much fuel to get to the moon.

In reality the numbers to get to LEO are lower because of staging and the vacuum engines on Starship which can be used in the upper atmosphere, and you also need fuel to get back from the moon, but it probably won't add up to a full Starship.

[1] https://www.reddit.com/r/space/comments/29cxi6/i_made_a_delt... [2] https://en.wikipedia.org/wiki/SpaceX_Raptor [3] https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation

Re: Starship / Super Heavy

#216

Post by inglor_cz »

sgt wrote: post #167
_lbaq wrote: post #158

Earlier quoted context omitted.

400 feet = 121.9 meters, 30 feet = 9.1 meters

Feet, not feets.

"Feets" evokes a vision of Gollum, looking at gleaming Starship and hissing "What a sssstrange fisssssh!"

A nice combination of SF and fantasy in one picture :-)

Re: Starship / Super Heavy

#217

Post by baq »

blackrock wrote: post #141

What are the odds of Starship working? It seems really complex. And that last phase where the ship flips vertical from the bellyflop, looks insane for human passengers inside. How many G’s is that maneuver pulling? SN8 appears 90% successful, but I’m wondering if that remaining 10% is the killer. As they say: You spend 10% of your time, solving 90% of your problem. And then you spend 90% of your time, solving the las…

SN8 was more like 99% successful. it only failed because the fuel mix became a bit too engine-rich. SN9 supposedly has a fix for that.

the biggest risk was the reverse belly flop and that went flawless to everyone's surprise. to quote musk, the crater is in the right place, and it didn't even properly explode anyway - the nose cone was more or less intact :) if the fuel pressure issue really is fixed and SN9 lands on the pad, it'll be a mark of a new age of space industry - and not that long after the previous one set by the same company! the most recent NRO mission flew on a booster used four times previously; fifteen years ago you'd be laughed out of the room for just suggesting the possibility of launching a national security payload on a used rocket.

Re: Starship / Super Heavy

#218

Post by TeMPOraL »

GordonS wrote: post #206
TeMPOraL wrote: post #177

Earlier quoted context omitted.

> While it will be fun to see humans on Mars, the really interesting stuff is further out. Where large lifters like this will really shine is in allowing automated mining factories to be sent to various space rocks in order to allow further, larger projects to be built in place. The way I see it, a lot of interesting things are closer than Mars. There's plenty of space rocks near Earth, that could be nudged into Eart…

> There's plenty of space rocks near Earth, that could be nudged into Earth orbit As a lay person, this sounds kind of dangerous - wouldn't there be a risk of the rock hurtling towards earth and causing a huge impact?

There would be, but it can be minimized. It would take a major mistake (or intentional action) to fail an orbital capture maneuver in such a way the asteroid would hit Earth instead. Most possible failures would just leave it hurtling through space, or orbiting the Earth in a suboptimal way. A correctly executed capture does not, at any point, pass through the state in which asteroid's trajectory would make it hit the planet - so one of the best mitigations would be designing the mission in such a way that engines fail safe, and any kind of deviation from mission parameters leads to engine shutdown.

Of course, the very capability of altering trajectory of asteroids creates risks of its own, similar to the capability of splitting atom.

Re: Starship / Super Heavy

#219

Post by m4rtink »

numpad0 wrote: post #199
iso947 wrote: post #189

Earlier quoted context omitted.

Statistics say you shouldn’t call your reusable ship a word beginning with ‘C’ In 1963 a LES killed someone, in 1983 it saved lives.

> In 1963 a LES killed someone Which manned abort in 1963 is that specifically? Why are you trying to skew discussion into some direction? Note: LES stands for Launch Escape System, usually a small solid rocket that activates in case of a failure during ascent to take the manned capsule away from exploding rocket under it, perhaps equivalent to airbags in a car.

IIRC this is the case when Soyuz LES activated on the pad before an unmanned test flight, killing some of the ground crew.

Re: Starship / Super Heavy

#220

Post by simonh »

iso947 wrote: post #191
SteveNuts wrote: post #84

Earlier quoted context omitted.

Didn't they do this in that movie armageddon? Hopefully space-x doesn't know something we don't.

Yes, two simultaneous shuttle launches from neighbouring pads Watching the two heavy boosters landing on neighbouring pads was similar - except real. It was that shot that made me think “the future is here”

After seeing single boosters land fine I wasn't expecting the dual simultaneous landings to have the emotional effect on me they did, but hot damn!
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