Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Starship's Third Flight Test [video]

spacex.com

Post reply on HN
Print view View original

231–240 of 413 posts

Re: Starship's Third Flight Test [video]

#231

Post by pixl97 »

cwillu wrote: post #118
elif wrote: post #77

Earlier quoted context omitted.

the instability was due to partial engine relight

It looked to me like there was some major oscillations shortly before the engines relit though.

Yea. If I had to make an uneducated guess I'm thinking one of two things.

1. Starship is leaky. Outgassing and/or leaky valves made attitude control difficult and used up ullage gasses quickly.

2. Thrust control/RCS has programming or physical issues. Saw a lot of ice breaking off places near deorbit, so if you had ice building up and redirecting gas the ship wouldn't perform as the computer expects.

Re: Starship's Third Flight Test [video]

#232

Post by cchance »

xondono wrote: post #127
enraged_camel wrote: post #117

Earlier quoted context omitted.

I think they also successfully demoed in-space fuel transfer.

Fuel transfer with what? That would require things like docking

They used tanks inside the ship to transfer from 1 to another to prove the process, was discussed and called out as success, and talked about many times before the flight

Re: Starship's Third Flight Test [video]

#233

Post by extraduder_ire »

enraged_camel wrote: post #134
xondono wrote: post #127

Earlier quoted context omitted.

Fuel transfer with what? That would require things like docking

They performed an in-ship fuel transfer, from one chamber to another. My understanding is that this is a very important pre-requisite for an actual transfer from one ship to another, because of the need to keep the fuel at cryogenic temperatures during the transfer, which is apparently not easy. Last time it was done was decades ago, but in kilograms. SpaceX just demoed a transfer of tons of fuel.

Bigger problem than keeping it cryogenic is getting it to one side of the tank while in orbit, so the pumps don't run "dry". Harder than just doing an ullage burn first too, because moving that amount of mass around also moves the vehicle.

Re: Starship's Third Flight Test [video]

#234

Post by cchance »

namaria wrote: post #9

I was just watching Spacex official stream and at ignition they switched to Musk hawking cryptocurrency. What just happened?? edit: wild I just realized take off is 50 minutes from now... what had I been watching?? they did a countdown and there was ignition... was that a time wrap? Am I going insane? edit2: @spacex034 is not @spacex... today I learned...

ya theirs a shitload of fake spacex streams with AI generated crypto scams

Re: Starship's Third Flight Test [video]

#235

Post by dotancohen »

exDM69 wrote: post #218
neffo wrote: post #196

Earlier quoted context omitted.

You need a second burn just to enter orbit. You burn at the top of the sub-orbital arc (opposite side of the earth) to enter orbit.

No, that's inefficient and real spacecraft don't do that for typical low earth orbits. Works in Kerbal Space Program, though. Normal orbital insertion is a single burn to orbit (with staging). With the correct initial roll and pitch, the spacecraft follows a perfect gravity turn and ends up in a near circular orbit at main engine cut off.

Do they typically burn softly until near apogee, then put on the power until raising the orbit on the other side to their current altitude? In KSP, I can easily get an orbit on a single burn (with staging) but getting it circular obviously requires adding energy at apogee.

Re: Starship's Third Flight Test [video]

#236

Post by apendleton »

bitcurious wrote: post #217
baq wrote: post #197

Earlier quoted context omitted.

99% chance that they lost attitude control hence couldn't point the business end towards wherever they wanted to. we know they can relight the engine on the booster and we know they can relight for landing burns. no surprise if the next launch has a couple pre-production big starlink birds.

> know they can relight the engine on the booster and we know they can relight for landing burns. Do we know that? Booster crashed into the water at full speed; landing reignition failed.

They did demonstrate this during their Starship-only bellyflop/landing tests a couple of years ago. This wasn't in space, though, obviously, and wasn't after an extended coast period. So... we know they can relight them under at least some circumstances, but whether or not they can under _these_ circumstances is maybe unclear.

Re: Starship's Third Flight Test [video]

#237

Post by dotancohen »

Plasmoid2000ad wrote: post #210
LorenDB wrote: post #203

Earlier quoted context omitted.

On the contrary, they absolutely had attitude control. Otherwise reentry would have seen the ship tumbling out of control and quickly breaking up. Instead, SpaceX was able to begin a controlled reentry in the upright position, indicating nominal orientation performance.

I'm no so sure, it at least looked like it was tumbling before and throughout re-entry. If they had attitude control, I think they would have at least stopped the visible rotation at some point before re-entry? I'm not sure why the ship not immediatly breaking up, but eventually breaking up is proof that they at attitude control - especially against what the live feed showed - rotation.

  > If they had attitude control, I think they would have at least stopped the visible rotation at some point before re-entry?
Maybe they thought the flaps would help stabilize once hitting some atmosphere. In fact, that seemed to happen though not before quite a bit of plasma cooked the unshielded side.

Re: Starship's Third Flight Test [video]

#238

Post by DiggyJohnson »

ajross wrote: post #174
DarmokJalad1701 wrote: post #167

Earlier quoted context omitted.

> They can't leave the Starship up in orbit, and where it reenters needs to be controlled. Why? Plenty of boosters re-enter uncontrolled and burn up all the time.

Stated simply: zero-thrust "orbits" repeat the same trajectory again and again. So if you end your burn in the outer atmosphere near your launch pad, the next time around you will be back in the outer atmosphere (near where the the launch pad "was", ignoring the rotation of the planet). And since there's air there providing resistance, you'll re-enter and crash. Getting to orbit requires at least one more burn near t…

Singe burn to orbit is pretty common though in reality, with the dynamics of staging, engine throttling, and precision insertion capabilities most modern rockets can hit the mark.

Re: Starship's Third Flight Test [video]

#239

Post by dotancohen »

TMWNN wrote: post #153
wongarsu wrote: post #144

Earlier quoted context omitted.

They have a great pipeline for building ships. They want reusability, but for near-term needs like deploying bigger Starlink satellites and their moon lander contract they could probably power through without reentry survival. It would be expensive, but unlike in-orbit refueling not really mission critical

My understanding is that Starship is financially comparable to Falcon 9 on a per-payload basis even if fully expended.

Comparable to Falcon 9? Unlikely - they've got three dozen Raptor engines on that thing, which alone account for the entire cost (not price) of a Falcon 9 flight. Maybe it is comparable to legacy launch providers, such as the Deltas and Atlases. But unlikely comparable to a Falcon 9 launch, even considering the larger payload.

Re: Starship's Third Flight Test [video]

#240

Post by gameshot911 »

DarmokJalad1701 wrote: post #80

The test is essentially a success at this point. Starship can take payload to orbit and open/close the payload doors. The remaining things are icing on the cake. They can refine re-usability while flying payloads.

I'm not sure the payload doors successfully opened and closed. Anyone have more details?
Post reply on HN