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SpaceX Starship Program / Re: SpaceX Raptor engine - General Thread 4
« Last post by niwax on Today at 08:24 am »
"almost" I'm considering 1km at sonic speed as almost sea level because it takes less than 3s to be under the water at that speed

My intention wasn't to steer this topic off topic, just to point out the fact that flight profile of the booster was so much off that conditions where engines tried to start were also completely off and it may as well be expected that they failed to start at those conditions

Unless my quick calculation is wrong, slowing from sonic to zero within 1km is merely ~4G. So very far from "almost hit the water" for a rocket and pretty much bang on for a landing burn.
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I see 5 pages of discussion about attitude control

And noone even thought about gyro-torquers?

https://link.springer.com/article/10.1134/S2075108722010060

Starship is too large for reaction wheels to be of much use (edit: unless you turn starship into an orbital telescope, then you'd need them for pointing accuracy)  but considering its non-negligible power reserves (tesla batteries) and payload capacity, I would suggest the reaction-wheels bigger cousin: Gyro-torquers.

AFAIK the ISS uses similar devices for attitude fine control.

This should be more than enough for

- Attitude fine control for docking
- Offsetting unwanted torques from thrusters and vents
- Radial propellant settling (for example for ship to ship transfer)

It would not be sufficient for attitude control when under thrust (but Raptor gimbaling can do that) and during reentry (Flaps should be able to do that)

One would still need some thrusters for propellant settling prior to main engine re-light, since then props need to be at the bottom of the tank, but  I think SpaceX already combined engine-prechill and ullage-thrusters


SpaceX will need that anyway for long coast phases (Mars transfer) since propellant evaporation during those flights is kept near zero and main tanks might be vented to vacuum for insulation - and you don't want to have a second RCS system that can run out of propellant or have issues with oxidizer creeping past seals and the like.

But even if you have an RCS system, having the torque-wheels for redundancy would be a great idea.
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Other US Launchers / Re: US Launch Schedule
« Last post by Salo on Today at 08:08 am »
https://spacepolicyonline.com/news/nasa-delays-next-artemis-missions-to-2025-and-2026/
Quote
SpaceX’s contract with NASA requires an uncrewed Starship HLS landing on the Moon before the Artemis III mission. That was another delay announced today. Instead of launching this year, SpaceX Vice President of Customer Operations and Integration Jessica Jensen said at the media telecon that it will be in 2025. The contract only requires SpaceX to land on the Moon, not lift off, but Jensen said the test was “an uncrewed landing on the Moon and then ascending off the surface.”
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Polls Section / Re: SpaceX Starship IFT-4 : When will it launch?
« Last post by rfdesigner on Today at 07:42 am »
My question is: how much does extra time does a flight that triggers a mishap investigation actually take?

Obviously none of us know quantitatively, but my guess is the impact is pretty minor.  I remember when we were in flight test and a test failed (obviously not a mishap), and the customer insisted on a root cause analysis, many of the design team chafed at "grounding" a jet.  But, in the end, we got a good product to the customer that they understood, and we understood better.

I'd suggest to those that are impatient, to look at the investigations as probably being the fastest path to a fully functional, operational, Starship.

Agreed.  "fail fast" is all about accepting you can't know everthing from design reviews, computer simulations and partial system tests.  So SpaceX test with early prototypes doing the real thing, to find out what really was necessary, and what really isn't.  The best time to incorporate the lessons learnt from those tests is right at the beginning of the project..   in the event you're mid way through a project and you don't have a time machine, the next best point is now.  Taking an extra month to act on ALL the lessons learnt is well worth it.
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June is the most optimistic prediction, I suppose.  :)
SpaceX needs to solve the difficult problems with Starship and SH landing.

only needs to solve raptor relight for next flight.
Landing is optional on both booster and ship.
Realy? Is it officially?
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Other US Launchers / Re: US Launch Schedule
« Last post by Salo on Today at 06:34 am »
https://twitter.com/jeff_foust/status/1769855034609615227
Quote
Jeff Foust @jeff_foust
The FAA's Kelvin Coleman says at the #payloadspacecapitol event this evening that he didn't see any major issues with last week's Starship launch, but SpaceX still needs to carry out a mishap investigation. SpaceX, he says, is aiming for 6-9 more Starship launches this year.

~ one launch per month.
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Rocket Lab / Re: Rocket Lab launch schedule
« Last post by Salo on Today at 06:18 am »
https://twitter.com/NatReconOfc/status/1769816107198599657
Quote
NRO @NatReconOfc
LAUNCH UPDATE: WELCOME TO LAUNCH WEEK!

We’re targeting no earlier than 2:40 a.m. EDT, March 21 to launch #NROL123 on a @RocketLab
 #Electron rocket from @NASAWallops
 at @Virginia_Space
 Mid-Atlantic Regional Spaceport.

Follow along this week to get ready for the launch!
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Other US Launchers / Re: US Launch Schedule
« Last post by Salo on Today at 06:18 am »
https://twitter.com/NatReconOfc/status/1769816107198599657
Quote
NRO @NatReconOfc
LAUNCH UPDATE: WELCOME TO LAUNCH WEEK!

We’re targeting no earlier than 2:40 a.m. EDT, March 21 to launch #NROL123 on a @RocketLab
 #Electron rocket from @NASAWallops
 at @Virginia_Space
 Mid-Atlantic Regional Spaceport.

Follow along this week to get ready for the launch!
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Other US Launchers / Re: US Launch Schedule
« Last post by Salo on Today at 06:00 am »
https://twitter.com/planet4589/status/1769913752298918147
Quote
Jonathan McDowell @planet4589
LAUNCH at 0228 UTC Mar 19 of 22 more Group 7 Starlink sats from Vandenberg Space Force Base, California
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Other US Launchers / Re: US Launch Schedule
« Last post by Salo on Today at 05:57 am »
Quote
SpaceX is targeting Monday, March 18 for a Falcon 9 launch of 22 Starlink satellites to low-Earth orbit from Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base in California. Liftoff is targeted for 7:28 p.m. PT, with backup opportunities available until 11:10 p.m. PT. If needed, additional opportunities are also available on Tuesday, March 19 starting at 7:38 p.m. PT.

A live webcast of this mission will begin on X @SpaceX about five minutes prior to liftoff. Watch live.

This is the 10th flight for the first stage booster supporting this mission, which previously launched SDA-0A, SARah-2, and seven Starlink missions. (=B1075-10) Following stage separation, the first stage will land on the Of Course I Still Love You droneship, which will be stationed in the Pacific Ocean.

https://www.spacex.com/launches/mission/?missionId=sl-7-16
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