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Author Topic: SpaceX News  (Read 49251 times)

WLJ

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Re: SpaceX News
« Reply #175 on: February 02, 2021, 05:47:00 PM »

Only for your personal skydiving needs.

Just playing on the fact you left out the word drogue   :laugh:
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AZRedhawk44

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Re: SpaceX News
« Reply #176 on: February 02, 2021, 06:12:32 PM »

I'm just saying to help slow it down a bit to gain a couple of seconds or so of time to sort things out and not to land the thing with. Drogue parachutes are a bit different from normal parachutes

A drogue chute would have zero effect on this thing.  It's about 125 metric tons.  You could use one of those M1 Abrams parachutes that kicks a heavy vehicle out of a C130 on a runway, it wouldn't be worth having.  In fact, a chute on the nose, even if it could hold up to the stresses and contribute in a meaningful way, would probably exacerbate the problem here.

The problem is partially the speed, but it's more around the over-correction of orientation due to Thrust Vector Control controlling the maneuver rather than Reaction Control System doing it.

The current RCS on these things is pitiful.  It's cold nitrogen compressed gas.  It's not nearly  enough to spin a steel building 90 degrees in a handful of seconds, and then stop that spin once perfectly vertical.

So what they're doing instead is using the Raptors.  When you light those things while it's horizontal, you get a bunch of horizontal velocity while you try and rotate its attitude.  That has to be negated.  What we see is the rocket rotate about 120 degrees, the TVC overcompensates in the opposite direction and cancels the horizontal velocity, then tries to come back to vertical again.

The center of rotation is closer to the nose fins while it does this.  You have to compensate for the angular momentum of nearly the whole ship, plus gravity, all at once.

SpaceX has a goal of putting hot-gas thrusters on this thing.  Tiny little methane/oxygen rocket engines similar to Raptor but much lower thrust.  Still way higher thrust than cold nitrogen though.  Using those will allow the center of rotation to move lower on the vehicle, rely on TVC of the main Raptors less, and reduce complication of the landing burn calculations.  And it would also hopefully avoid the over-correction issue entirely.  You can't avoid it if you're using your main propulsion engines to rotate the whole craft 90 degrees.

One other problem they're having is maintaining proper fuel pressure.  During ascent this thing sucks fuel from the main tanks, right above the engines.  But at the landing maneuver, fuel feed is shifted to alternate smaller tanks.  One is in the nosecone and the other is nested inside the main tank (can't remember which is O2 or CH4 and it really isn't relevant to the problem).  There is less slosh during the horizontal-to-vertical maneuver if a tank is full, and these landing tanks are tiny compared to the launch tanks.  The Raptor engine is supposed to be able to autogenously pressurize these fuel tanks with a little bit of exhaust, to keep the fuel supply steady.  That's not working quite as expected, so they are augmenting that with COPV canisters filled with nitrogen or helium or something, to boost gas pressure in the landing tanks. 

Parachutes are just not the answer to this problem.  A parachute of the scale to have any impact on this vehicle would weigh more than several seconds of fuel to burn to impart more authority to the landing maneuver.
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230RN

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Re: SpaceX News
« Reply #177 on: February 02, 2021, 06:17:38 PM »

How about pop-out and retractable panels of the actual rocket skin?  Rapid deployment, stable aero characteristics, not much extra mass for the trip (just the additional deployment and retraction mechanics) since the skin is part of the ship's normal carry load. Just a little extra drag on the trip down.  Only major problem I foresee is hinging the panel since they're part of the curved surfaces of the skin.

Merely suggestive of what I'm getting at:

   

Don't take that literally, it's just food for thought.  We could call them drag panels (not drogue panels.)

Should I send this idea to SpaceX?

Is it patentable?

Terry, 230RN
« Last Edit: February 02, 2021, 06:34:51 PM by 230RN »

WLJ

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Re: SpaceX News
« Reply #178 on: February 02, 2021, 09:43:51 PM »

Looks like Musk may have more to worry about now

DOJ Targets Elon Musk’s SpaceX For Allegedly Preferring To Hire U.S. Citizens
https://www.dailywire.com/news/doj-targets-elon-musks-spacex-for-allegedly-preferring-to-hire-u-s-citizens?utm_source=facebook&utm_medium=social&utm_campaign=mjk

And the drogue chute idea was just that an idea
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AZRedhawk44

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Re: SpaceX News
« Reply #179 on: February 02, 2021, 09:48:20 PM »

Looks like Musk may have more to worry about now

DOJ Targets Elon Musk’s SpaceX For Allegedly Preferring To Hire U.S. Citizens
https://www.dailywire.com/news/doj-targets-elon-musks-spacex-for-allegedly-preferring-to-hire-u-s-citizens?utm_source=facebook&utm_medium=social&utm_campaign=mjk

And the drogue chute idea was just that an idea

They probably just don't want to *expletive deleted*ck with any HR schisms regarding ITAR.

And, foreign nationals are more likely to be a security risk.  SpaceX doesn't do patents.  They rely entirely on internal security for their IP protection.
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Boomhauer

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Re: SpaceX News
« Reply #180 on: February 02, 2021, 09:52:32 PM »

Looks like Musk may have more to worry about now

DOJ Targets Elon Musk’s SpaceX For Allegedly Preferring To Hire U.S. Citizens
https://www.dailywire.com/news/doj-targets-elon-musks-spacex-for-allegedly-preferring-to-hire-u-s-citizens?utm_source=facebook&utm_medium=social&utm_campaign=mjk

And the drogue chute idea was just that an idea

And so it begins


Guess who also prefers to hire US citizens? The entire *expletive deleted*ing US government. In fact if you don’t already work for the government it’s damn near impossible to get on with them. If you go on USAjobs.gov you will see most of the positions require previous federal service, US citizenship, and have other preferential qualifications.

But god forbid SpaceX implement a tenth of that. No no, bad company!
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WLJ

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Re: SpaceX News
« Reply #181 on: February 02, 2021, 10:19:12 PM »

I just drank a toast to SN9, may her sacrifice be not in vain.
Be brave SN10, be brave

Okay, maybe I drank too much of a toast   :laugh:
« Last Edit: February 02, 2021, 11:06:52 PM by WLJ »
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WLJ

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Re: SpaceX News
« Reply #182 on: February 02, 2021, 10:36:46 PM »

This view just gives me the willies about the whole "belly flop" idea. Hopefully they can get this worked out

https://youtu.be/CTwBllaqcME?t=777
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RocketMan

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Re: SpaceX News
« Reply #183 on: February 02, 2021, 10:47:10 PM »

Yep, something flew out of the hind end of the rocket during the engine ignition sequence.  Wonder what it was?
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kgbsquirrel

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Re: SpaceX News
« Reply #184 on: February 03, 2021, 12:21:37 AM »

Yep, something flew out of the hind end of the rocket during the engine ignition sequence.  Wonder what it was?

Something important I'd wager.  :laugh:

WLJ

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Re: SpaceX News
« Reply #185 on: February 03, 2021, 10:26:33 AM »

More on that FAA business
Apparently for SN8's flight back in Dec Musk flipped off the FAA and the FAA didn't take kindly to it.

Quote
Before the December test flight, SpaceX had sought a waiver from the Federal Aviation Administration that would have allowed it “to exceed the maximum public risk allowed by federal safety regulations,” the agency said in a statement Tuesday.

But after that waiver was denied, SpaceX proceeded with the flight, violating its launch license in what aerospace and industry officials said was a potentially reckless move that could have posed serious risk to the public’s safety.

As a result of the violation, the FAA directed Elon Musk’s company to investigate the incident and suspend operations that could affect public safety at its launch site in South Texas.

Ultimately, the investigation ended, the FAA approved the company’s remedies and granted it approval to attempt Tuesday’s test.

SpaceX crashes another Starship in test that was delayed over FAA concerns company violated its test license in December
https://www.washingtonpost.com/technology/2021/02/02/spacex-test-sn9-faa-license/
« Last Edit: February 03, 2021, 11:38:18 AM by WLJ »
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WLJ

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Re: SpaceX News
« Reply #186 on: February 03, 2021, 10:44:45 AM »

Good views and analysis of what happened from Scott Manley

SpaceX Starship Number 9 Makes Perfect* Flight (*except for the landing which was a huge fireball)
https://www.youtube.com/watch?v=zwZl6YV3xYA
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MechAg94

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Re: SpaceX News
« Reply #187 on: February 03, 2021, 11:23:18 AM »

This view just gives me the willies about the whole "belly flop" idea. Hopefully they can get this worked out

https://youtu.be/CTwBllaqcME?t=777
That angle caught my attention also.  Just illustrates how low they allow it to go before going vertical and igniting the engines for landing.  Also illustrates just how big that thing is.
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WLJ

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Re: SpaceX News
« Reply #188 on: February 04, 2021, 11:15:54 AM »

"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us".
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WLJ

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Re: SpaceX News
« Reply #189 on: February 04, 2021, 12:42:43 PM »

"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us".
- Calvin and Hobbes

WLJ

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Re: SpaceX News
« Reply #190 on: February 04, 2021, 01:49:55 PM »

"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us".
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WLJ

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« Last Edit: February 04, 2021, 05:40:09 PM by WLJ »
"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us".
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kgbsquirrel

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Re: SpaceX News
« Reply #192 on: February 04, 2021, 06:02:59 PM »

Wondering if they didn't do the three engine config first go around because of supply limits from the current header tanks.

AZRedhawk44

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Re: SpaceX News
« Reply #193 on: February 04, 2021, 08:23:50 PM »

Wondering if they didn't do the three engine config first go around because of supply limits from the current header tanks.

I think it's just too much blind faith in the Raptor ignition system, and a belief that 3 engines will overpower what they're trying to do.
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kgbsquirrel

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Re: SpaceX News
« Reply #194 on: February 04, 2021, 09:11:00 PM »

I think it's just too much blind faith in the Raptor ignition system, and a belief that 3 engines will overpower what they're trying to do.

Blind faith?  The engine is still in unmanned experimental R&D. Blind faith is was Boeing was doing with 737 that cost actual lives.

WLJ

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Re: SpaceX News
« Reply #195 on: February 04, 2021, 11:02:05 PM »

Things you find on the internet

"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us".
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WLJ

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Re: SpaceX News
« Reply #196 on: February 04, 2021, 11:04:19 PM »

"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us".
- Calvin and Hobbes

kgbsquirrel

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Re: SpaceX News
« Reply #197 on: February 04, 2021, 11:27:23 PM »

Things you find on the internet



Experimental rockets have exceptionally short life expectancies.   =D

dogmush

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Re: SpaceX News
« Reply #198 on: February 05, 2021, 07:05:56 AM »

Worth remembering that this video is only three years old:

https://youtu.be/bvim4rsNHkQ

WLJ

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Re: SpaceX News
« Reply #199 on: February 05, 2021, 12:46:47 PM »

Worth remembering that this video is only three years old:

https://youtu.be/bvim4rsNHkQ

Yep
I need to remember to look up how many rockets NASA has had go boom just on the way up.

SN10 is getting it's Raptors installed https://www.youtube.com/watch?v=Z72Au8Px7mM
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