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

321–330 of 413 posts

Re: Starship's Third Flight Test [video]

#321

Post by dzhiurgis »

dotancohen wrote: post #239
TMWNN wrote: post #153

Earlier quoted context omitted.

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.

You are launching 8x more payload vs ~15 reuses of Falcon9

Re: Starship's Third Flight Test [video]

#322

Post by elihu »

tempaway444641 wrote: post #221
simfoo wrote: post #54

1000 km/h booster impact at sea, call that a "soft landing/splash down". Poor fishies :)

It does look like it came down rather fast. Engines only partially re-lit. About 34min in this video https://www.youtube.com/watch?v=NWM1NQ1tZEU&t=2112s

I think that's the ascent burn. It doesn't look like the engines re-lit at all for the descent. (I imagine they aren't supposed to light until they're a lot closer to the ground than they were when the video was lost.)

Re: Starship's Third Flight Test [video]

#323

Post by HeyLaughingBoy »

kristianp wrote: post #318
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.

Maybe the words "success" and "failure" are too difficult to shoehorn into describing these tests, especially with the first two tests. "Great progress" is a good intermediate.

When you write a test case, you define what "Passed" means. If this test flight overall meets SpaceX's definition of "Passed", then it was a success, regardless of what anyone else thinks it should mean.

Re: Starship's Third Flight Test [video]

#325

Post by hnbad »

Hamuko wrote: post #119
atonse wrote: post #83

Earlier quoted context omitted.

Twitter was a video platform before Musk took over. They were doing Thursday night football (NFL) and other things. Looking at the SpaceX feed, they seem to be using whatever tech they got from the Periscope acquisition (at least the servers were still pscp.tv).

Twitter was not a video platform – it had (some) video features. Very different. And people always considered Twitter videos to absolutely suck.

That hasn't really changed though. He's just decided to manifest "Twitter is a video platform" into existence. The controls are still total ass though.

Re: Starship's Third Flight Test [video]

#326

Post by grecy »

avmich wrote: post #305
mgiampapa wrote: post #288

Earlier quoted context omitted.

Passenger rating isn't even in the cards for Starship for a long time. You ride to LEO on a Falcon-9 with a proven track record for the foreseeable future.

"Foreseeable" is roughly "five years"? Starship HLS (Human Landing System) is currently planned to land on the Moon, with people, in 2026. It may very well slip a year, two or three - but landing on the Moon this decade still seems quite possible. Or you consider "passengers" different enough than "crew"?

Interesting Asterix on that is the humans will only be on Starship from Lunar orbit down to the moon surface and then back to lunar orbit again.

No humans aboard during Starship launch, transit to and from the moon or re-entry.

(For completeness, humans will do all that other stuff aboard SLS and Orion. Starship literally only ferries them down the moon and back up again)

Re: Starship's Third Flight Test [video]

#327

Post by grecy »

perihelions wrote: post #187
grecy wrote: post #163

Earlier quoted context omitted.

That is really cool. For those of us that are space nerds but don't have the depth of understanding, do you mind walking us through the calculation above?

I apologize I don't have a good explanation of it at hand! It's a form of the vis-viva equation [0] that's basically a restatement of conservation of energy. It derives the (scalar) speed of an object in a 2-body orbit, at any position within that orbit, as a simple function of their separation distance. In the form I'm using, I'm using standard parameters of an elliptical orbit: the periapsis (the closest approach t…

No apology needed, thankyou very much!

Re: Starship's Third Flight Test [video]

#328

Post by ericbarrett »

exDM69 wrote: post #242
dotancohen wrote: post #235

Earlier quoted context omitted.

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.

No, most rocket engines have quite limited amount of throttle capability and run near maximum thrust until cutoff. The rocket yaws and pitches in the first seconds of flight while the vehicle is still subsonic, then flies a gravity turn trajectory at zero angle of attack (facing the direction of travel) at near maximum thrust. Any errors accumulated during early part of the flight will be corrected by adjusting the t…

MechJeb + Realism Overhaul offers a "Primer Vector Guidance" ascent controller that (I think) is based on the space shuttle's Powered Explicit Guidance. It's definitely designed to work with more realistic spacecraft; it can ullage with RCS, doesn't need to throttle, etc.

Re: Starship's Third Flight Test [video]

#329

Post by was_a_dev »

pfdietz wrote: post #320

It got much farther than IFT-2, and exposed new problems, which is the purpose of a test flight. This seems like a success. Things will only be bad if some problem is exposed that doesn't look solvable.

I'm happy they have some data with respect to re-entry. It would have been nice to see the vehicle survive for longer, but there's something to go forward with.

Re: Starship's Third Flight Test [video]

#330

Post by pclmulqdq »

HeyLaughingBoy wrote: post #323
kristianp wrote: post #318

Earlier quoted context omitted.

Maybe the words "success" and "failure" are too difficult to shoehorn into describing these tests, especially with the first two tests. "Great progress" is a good intermediate.

When you write a test case, you define what "Passed" means. If this test flight overall meets SpaceX's definition of "Passed", then it was a success, regardless of what anyone else thinks it should mean.

If your test case for left pad passes when it outputs a string of the right length, your boss is going to judge whether it's a good test case. Since this is all being done on federal grant money, it's legitimate to have higher expectations. This test was good, though - the previous two were disappointing.
Post reply on HN