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SpaceX launches Starship v3 rocket

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Re: SpaceX launches Starship v3 rocket

#221

Post by jdranczewski »

glzone1 wrote: post #112

Does anyone know how important hot staging is? It seems to give the booster a real kick - what's that do to turbo's and fuel movement? You've got hot exhaust onto cold cryo fuel tank header? You've got to carry more mass in terms of protection for the tank? Is doing MECO and then push and then get 100 yards apart or something before second stage / ship engines kick on a big enough penalty to justify all the extra com…

They were originally planning to not do hot staging, aiming instead for a somewhat funny approach where they spin the ship and booster slightly so they are passively separated by centrifugal forces. A bunch of things went wrong in the first test flight, so this was never attempted, and they switched to the "simpler" hot staging in flight 2.

Re: SpaceX launches Starship v3 rocket

#222

Post by dmix »

ls612 wrote: post #193
throwaway85825 wrote: post #166

Earlier quoted context omitted.

The F-35 is designed to be able to break into and defeat modern air defense networks. The gripen is a much less capable non expeditonary platform designed to maximize asymmetric losses if sweden is invaded. As a small country sweden has to follow a porcupine strategy to deter invasion. Presently the actual comparable to the F-35 is attritable drones, which is why every mid-size and major power is developing them.

The Russians have been trying to use attritable drones for years to break down the Ukrainian IADS and have not yet succeeded. Meanwhile the Israeli F35 fleet with no direct American support was able to crack open Iran’s air defenses at the start of the Twelve Day War with relative ease.

Israel used long range air launched ballistic missiles (ROCKS) and cruise missiles, mostly from F15s, to degrade Iran's ancient radar network and S300s (which allegedly weren't moved around much). That was before the invasion, so Iran didn't have much long range radar coverage when the war started.

Re: SpaceX launches Starship v3 rocket

#223

Post by laughing_man »

fooblaster wrote: post #183
laughing_man wrote: post #158

Earlier quoted context omitted.

All what tiles breaking and needing repair? There was remarkably little visible damage this time around compared with previous flights. There's no materials science breakthrough needed -- the shuttle used ceramic tiles successfully its entire service life. What's needed is engineering work, and that's what SpaceX has been doing.

You know a whole the size of a quarter can wreck the entire spacecraft and make it effectively throw away? Also, you'd want to use this many times. Making a system robust while not requiring months of refurbishment is really really hard.

I doubt that. It's made of stainless steel. If it gets home safely they can patch it.

Re: SpaceX launches Starship v3 rocket

#224

Post by dredmorbius »

itishappy wrote: post #99
dylan604 wrote: post #70

Earlier quoted context omitted.

“Like a rocket” is a phrase for a reason

Eh, they've left some performance on the table: > Sprint accelerated at 100 g, reaching a speed of Mach 10 (12,000 km/h; 7,600 mph) in 5 seconds. Such a high velocity at relatively low altitudes created skin temperatures up to 6,200 °F (3,400 °C), requiring an ablative shield to dissipate the heat. The high temperature caused a plasma to form around the missile, requiring extremely powerful radio signals to reach it…

Then there's HIBEX, which hit 400g acceleration.

(Via a Wikipedia rabbit-hole thanks to your comment.)

https://en.wikipedia.org/wiki/Hardpoint_(missile_defense)>

Re: SpaceX launches Starship v3 rocket

#225

Post by murderfs »

kibwen wrote: post #186
s1artibartfast wrote: post #177

Earlier quoted context omitted.

In short, the more stages the better to discard mass once it isnt necessary, and the larger to the better to improve the ratio of (ship+payload) to fuel. Here is a decent summary. https://gemini.google.com/share/121466b300c1

This is only true to an extent. Yes, a larger rocket means a better mass:payload ratio, but a larger rocket also means more mass in absolute terms, and more mass means more fuel, and more fuel means more mass, and more mass means more fuel, and more fuel means more mass, and so on. This is "the tyranny of the rocket equation", and it places an upper bound on the size of rockets that need to carry their own fuel for a…

> This is why, for example, despite the existence of jumbo jets (which have a better mass:payload ration than smaller planes), most passenger flights are not on jumbo jets, because there's just not enough demand on most routes.

Airlines used to use a hub and spoke model where it would make sense to have larger planes between hubs and smaller ones to get to and from the hubs, but consumers strongly preferred direct routing, so it didn't work out. For orbital payloads, most payloads probably do not mind too much if it takes a month or more to boost/deboost themselves to their intended orbits.

Re: SpaceX launches Starship v3 rocket

#226

Post by hgoel »

zoogeny wrote: post #192
hgoel wrote: post #123

Earlier quoted context omitted.

The argument for the IPO was to fund their space datacenters project, if Musk could afford to ignore the stock price, that wouldn't be needed.

At this point in time, Musk can afford to ignore the stock price since he will retain sufficient shares (with 10x voting rights if I am understanding correctly) to outvote any board. However, some projections I have seen suggest even the public raise won't be enough for the entire vision (which includes LEO data centers AND trips to the Moon and Mars). That means he will either have to find the revenue or eventually…

That's the thing, why does everyone seem convinced that the guy who has been making up pie in the sky projects and breaking his promises, won't find himself wanting more money?

Have IPOs ever been about just a one time cash infusion?

Re: SpaceX launches Starship v3 rocket

#227

Post by palata »

fc417fc802 wrote: post #79
jmyeet wrote: post #46

It's worth remembering that, according to SpaceX's own filings, they've spent >$15 billion on the Starship program thus far with more to come. And SpaceX is burning cash still, particularly because Elon Musk bailed out his own bad decisions with Twitter and xAI with SpaceX stock, basically. Flight 12 was a relative success. Some engines failed to light but that's an unintended good test. Rockets are typically designe…

> At this point, the entire SpaceX project is a bet on telecommunications services, specifically direct-to-satellite handheld Internet. That's the only market that will recoup the program costs. I seriously doubt that. Just for example, mining a single asteroid has the potential to flood the market for any number of metals. I don't pretend to know how expensive it would be to achieve that in practice; my point is tha…

Are you saying "I don't know how expensive it would be to achieve that, but it won't prevent me from mentioning it as an economically viable option"?

Re: SpaceX launches Starship v3 rocket

#228

Post by sysworld »

maxlin wrote: post #194
SV_BubbleTime wrote: post #105

Earlier quoted context omitted.

So crazy that the NBC video didn’t include that! It’s still not as bad as NASA skipping the good view of the live separation.

Better to always watch from the official source, the only one that is in 4k too AFAIK https://x.com/SpaceX/status/2057843818859209147

Thank you!! I started watching on NBC and there video quality is potato.

Re: SpaceX launches Starship v3 rocket

#229

Post by robocat »

xiphias2 wrote: post #198
hgoel wrote: post #92

Earlier quoted context omitted.

Shame they're risking that ability with the IPO. We've seen how irrational and ignorant stock traders are from other publicly traded space companies. Even scrubbed launches cause the price to dip.

Elon negotiated with Nasdaq to automatically accept it in Nasdaq 100 index after 15 days, so the stock traders don't really matter.

Can you point me to a source that actually says that Elon influenced the Nasdaq?

The whole thing stinks, and we can create stories since some incentives are obvious.

Stock traders do matter since 30% of stock is aimed at retail (very unusual % - what is the norm?)

More info here: https://www.youtube.com/watch?v=-X6YzlY_8tM (sorry, video)

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