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#1851 2024-06-07 12:16:01

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 18,066

Re: Starship is Go...

For GW Johnson ... someone in the forum reported recently that the engine outages were planned.

Please keep a watch for more detailed reports, and let us know what you find out.

It would make sense to plan to launch with an engine out, and this is as good a time as any to find out.

The same would seem advisable for the return to the chopsticks, although I would ** think ** there would be lots more engines to choose from.

On the ** other ** hand, there may be a small number of engines assigned the special duty of dancing a pole on it's point.

The ability to adjust the angle of thrust rapidly is (or would seem to be) a requirement for that application.

Hopefully SpaceX will publish a few more details.

(th)

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#1852 2024-06-07 14:07:03

kbd512
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Registered: 2015-01-02
Posts: 7,590

Re: Starship is Go...

GW,

I watched at least a half dozen videos of IFT-4 that day, but the callout was only on one of the videos, so maybe it was not intentional.  It was made by a guy narrating the launch, though.  I've heard that same voice narrate multiple Falcon 9 launches and I've seen his face a few times before during the launch coverage.  However, I do not recall if he works for NASA, SpaceX, or someone else.  He's an older guy, in his 50s at least, partly bald, was wearing glasses on the launches I recall.  He's covered the SpaceX crewed launches before, so he could be a NASA employee.  I can't remember his name, but I do remember his voice, because I've heard it before multiple times during previous launches.

Is it possible that Super Heavy's engine-out was not anticipated and he doesn't know what he's talking about?

That is entirely possible.  All I remember is him calling it out on one of the live feeds.  I don't have definitive proof in the form of telemetry data to prove it was a commanded engine shutdown.  It seemed entirely plausible that operation of that singular engine was terminated on command to test a worst case engine-out.  Regardless of what was intended, we now know that a single engine-out can be handled, even if it happens at the worst possible time (mere seconds after liftoff when the vehicle is heaviest).

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#1853 2024-06-07 14:33:02

Void
Member
Registered: 2011-12-29
Posts: 7,354

Re: Starship is Go...

I think I recall the mention of an intentional engine out for the Super Heavy.

I will say something I think I observed about the flap which was in view.

Flap Control at 85 km, 26,719 speed.
Peak Heating at 71 km, 25,832 speed.
End of temperature rise at 68 km, 24,000 speed.
Particles Apparent at 68 km, 22,263 speed.
Increased Pressures at 62 km, 20, 287 speed.
Burning Through seems to start at 55 km, 14,738 speed.

I am wondering if a sort of cutting torch effect was occurring when the burn though became apparent.
Pressures were increasing, so perhaps more Oxygen, and then also the residual heat and real time heat from compression.

The metal being a fuel.

So, heat, Oxidizer, and exposed metal as a fuel, I presume.

It only looked that way to me, it may not be true.

There was talk of a loss of a tile, but I don't know when that occurred.  Elon Musk said he was surprised that the Stainless Steel held up so well.

I have thought as a first resort that perhaps the thruster method of navigation might allow the insertion of a gas into the hinge.  But I don't know if that would help or hurt.

One question might be if you could combine the thruster method with the flaps.  Granted, if it is hot exhaust, then it is only marginally better than the plasma.

But rocket exhaust has been used as a heat shielding method in a very limited way, by the Falcon 9 1st stage, I believe.  It would certainly be good if you could use a cold gas, but that may not be practical.

Anyway, don't get hung up on what I said, I want a best solution that may not be what I have suggested.  And it is not certain if a cutting torch effect was in fact what was happening.

Pardon me, if necessary,

Done

Last edited by Void (2024-06-07 14:48:21)


Done.

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#1854 2024-06-07 19:37:25

Void
Member
Registered: 2011-12-29
Posts: 7,354

Re: Starship is Go...

I haven't been commanded to silence yet and have found a bit more information so I will say some more, hopefully it can be tolerated.

I understand that new starships will likely have flaps more to the leeward side and that may help some.

Also, I understand that the hinged flaps have some seals that apparently failed at least on one flap.

So, my thinking goes to a "Gland" fluid to the hinge compartment.

In the mines we used "Gland-Water".  On starship, you would use a "Gland-Gas".
https://www.maric.com/wp-content/upload … l-V919.pdf
Quote:

Gland water is a term used in the mining industry to refer to the sealing or packing water supplied to the glands of centrifugal pumps fitted with conventional gland-packing type sealing arrangements1. It is used in conjunction with Gland Packing and most common in Warman Pumps2. The gland water is supplied at a pressure higher than the chamber pressure into a lantern ring. The gland water lubricates the packing to the shaft and keeps the slurry away2. Leakage to atmosphere is gland water2.

I know that a gas is used to orient the ship prior to the flaps taking over.  This was cold gas thrusters before.  But now I think they are trying to use exhaust.  Of course, this may be hotter than wanted, I am not sure.  Perhaps there is a way to sink the heat of the gas into ship structure prior to pressurizing the hinge compartment with it.

The intent would be to keep the plasma and then hot oxidize air out, to prevent chemical reactions, and perhaps to reduce heating.

I have thought of the thrusters being in companionship with the flaps, so that the flaps could deflect the outgassing to an advantage, but I would also fear to make tiles come off with that action.

Anyway, the good news about flight #4 was that it may be possible to land a starship or ditch it in the ocean, even if there are flap problems.

In the case of the landing then a repair of the flaps might be the major need to bring it back to service.

I make these suggestions with good intent. 

But I am even more happy is someone comes up with a better plan.

Done

Last edited by Void (2024-06-07 19:47:42)


Done.

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#1855 2024-06-08 08:57:10

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,300

Re: Starship is Go...

Normal engines out during the flight path is expected to be done to save fuel and capability for the unexpected. But not normal is when an engine fails such as the 1 did on the BFR stage. One can only turn on normal off engines when you have extra engines to do so which could be done on the starship during the landing if required.

Seems that based on the heat getting into the wing would call for design changes and other testing flights.

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#1856 2024-06-08 09:43:14

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,609
Website

Re: Starship is Go...

My observations in post 1850 above have an error.  Seeing the video again,  I found the error. 

Superheavy booster post-staging:  the boostback burn was indeed 13 of 13 intended engines.  The engine-out showed up in the landing burn.  Initially the landing burn showed 12 of an intended 13 engines,  cut back to 3 of an intended 3 for the actual touchdown. 

Superheavy booster ascent:  showed 32 of 33 intended engines,  right off the launch pad.  No changes.

Starship upper stage:  no changes. 

That's 2 different engines seen out on Superheavy,  and none on Starship.  Whether one of those was planned,  I do not know.  But I would rather doubt that 2 were planned. 

Bear in mind that the 3 vacuum engines aboard Starship do NOT gimbal.  Only the 3 sea level engines in the center gimbal,  and by a large degree,  for thrust vectoring.  They have to,  to make the flip.

On Superheavy,  the outer ring of 20 engines,  and the middle ring of 10 engines,  do not gimbal.  Only the three center engines gimbal,  and by a large degree,  for thrust vectoring.  They have to,  in order to make the powered flip at staging.

The vulnerability here is the 3 gimballing engines on each of the stages.  What if 1 fails?  Can it still adequately thrust vector?  Is there still enough thrust to settle propellants in the Superheavy?  Is there enough acceleration in the Starship to touchdown without massive impact on only 2? Same goes for Superheavy.  SpaceX does seem to be using last-second maneuvers in their descent plans. 

GW

Last edited by GW Johnson (2024-06-08 09:50:17)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#1857 2024-06-08 10:48:24

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,609
Website

Re: Starship is Go...

There is now some sort of on-the-surface camera footage of the Superheavy landing.  The bigger short burst of tailpipe flame is 12 of 13 intended engines.  It is obscured by cloud,  then visible again on 3 engines vectoring to touchdown.  There is clearly a fire going on in the engine bay,  with that subsonic plume of flame bending upwards with the slipstream.  Odds are that fire is associated with the engine that was out in the middle ring of 10.  Landing in the water is what put that fire out.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#1858 2024-06-08 13:46:15

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 18,066

Re: Starship is Go...

For GW Johnson re engine out ...

Greg Stanley included confirmation of engines out during launch and landing in one of his slides.

Dr. Stanley is speaking now if anyone tunes into northhoustonspace.org

(th)

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#1859 2024-06-08 17:19:14

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,419

Re: Starship is Go...

Here's the available video of the landing of super heavy.

https://www.youtube.com/watch?v=tMz8GxU … WL&index=2

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#1860 2024-06-10 16:22:25

Void
Member
Registered: 2011-12-29
Posts: 7,354

Re: Starship is Go...

Well, I like the content of this Video: https://www.youtube.com/watch?v=uxkYTEK5NCU
Quote:

SpaceX Is Adding Another Heat Shield Layer To Starship

TheSpaceBucket
40.7K subscribers

My feeling is that could go long way towards making the device usable, even for humans eventually.

If an Ablative layer, under the tile layer, could be stable during repeated reheating to a low level that could be workable.

I also think that eventually with space infrastructure, some repairs to ships in orbit may become possible to increase success rates for return from orbit.

The video also seems to have the opinion that perhaps only one flap was damaged.  It also sounds like Elon Musk indicates that they are rather confident about also improving the flap methods.

Done

Last edited by Void (2024-06-10 16:27:29)


Done.

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#1861 2024-06-11 09:11:33

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,609
Website

Re: Starship is Go...

I followed the link and all I saw was a series of commercial ads,  not anything to do with Starship. 

Void,  I think that may be the wrong link.  Check it out and correct it,  if it is.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#1862 2024-06-11 09:31:09

Void
Member
Registered: 2011-12-29
Posts: 7,354

Re: Starship is Go...

Well, the internet/computers can be weird.

I just started the video on my phone, and am now running it on my computer in the background.

The video indicates that the new heat shield system tiles should be twice as strong.  Also they are going to put an ablative underlayer that may save the day if a tile is cracked or breaks off.

They apparently also have plans to improve the flaps, but no particular description of how to do that.  I think the worked sealed was used at some point.  I have seen 2 or 3 different videos about this.

I would think that if they had some damage from falling back to the ablative, perhaps the metal would be reduced in needed quality.  But I might speculate that some kind of ugly patch might make that Starship usable for an expendable use.  Also, in such a case perhaps the heat shield and flaps could be removed as it would no longer be trusted.

But that is just my thinking.

I would trust a 2nd use on an undamaged Starship more than a first use.

I suppose over time they might classify ships of the basis of wear and tear, and types of patching.

Again, just my opinion.

Hope the link will work for you now.

https://www.youtube.com/watch?v=uxkYTEK5NCU

Done

Last edited by Void (2024-06-11 09:40:03)


Done.

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#1863 2024-06-11 12:25:40

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,609
Website

Re: Starship is Go...

Void:

I used both links,  and they both worked correctly this time!  I have no clue what happened the first time I used the first link you posted.  All I did was click on the link.  It took me to some gal's ad for an unproven weight loss technique that had something to do with coffee.  Followed immediately by another ad that I simply did not watch.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#1864 2024-06-12 12:40:29

Void
Member
Registered: 2011-12-29
Posts: 7,354

Re: Starship is Go...

Here is some more talking which might be useful: https://www.youtube.com/watch?v=moV420fEzTY
Quote:

STARSHIP Insights Everyone Missed! W/ Scott Walter

Dr. Know-it-all Knows it all
80.8K subscribers

Says that on launch engine failure did not occur but lighting it was aborted for some reason.

Done

Last edited by Void (2024-06-12 12:42:10)


Done.

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#1865 2024-06-13 07:03:01

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,609
Website

Re: Starship is Go...

Nice find,  Spacenut.  That explains what all the talk about a "planned engine out" really was.  They had one that would not light,  and decided to fly without it.  That's where the advantage of so many engines shows up:  1 out of 33 is only a 3% loss of thrust.  That one was in the outer ring of 20. 

The boostback burn used the inner ring of 10 plus the 3 center engines that gimbal.  I saw all 13 burning there. 

It was the landing burn that initially used the same 13,  transitioning to only the center 3 for touchdown.  Only 9 of the inner ring of 10 were lit for that burn (which was the second engine-out),  and one could see subsonic flame out to one side blown back up along the side of the stage as it landed.  Looked rather like a methane-air fire,  most likely a result of the engine that was out.  Probably tried to light and had a failure of some kind,  that damaged plumbing somewhere causing a methane leak. Had oxygen also spilled,  the fire would have been instead an explosion.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#1866 2024-06-13 08:07:29

RGClark
Member
From: Philadelphia, PA
Registered: 2006-07-05
Posts: 744
Website

Re: Starship is Go...

kbd512 wrote:

At $20M per copy, SpaceX can afford to "blow up" 7 Starships and Super Heavy boosters before they reach the cost of a single RS-25E engine for the Space Launch System.  Nominally, SpaceX would not blow up any vehicles, but if that is what they must do to learn and push the hardware to its limits, then I think NASA and the US Air Force are getting their money's worth out of the test program.  Sometimes you have to "break things" to learn what not to do.  The flight testing phase of development is the correct time to intentionally try to break everything.

Actually, Elon has said it cost about $95 million to launch a SuperHeavy/Starship.

  Bob Clark


Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):

      “Anything worth doing is worth doing for a billion dollars.”

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#1867 2024-06-13 08:22:42

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,590

Re: Starship is Go...

RGClark,

I stand corrected.  I thought I heard Elon Musk throw out that number during an interview.  Either way, SpaceX gets an entire rocket launch for $95M.  NASA doesn't get one RS-25 engine for $95M.

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#1868 2024-06-13 18:51:51

Void
Member
Registered: 2011-12-29
Posts: 7,354

Re: Starship is Go...

I think that numbers get better if reusability is established in a better way than was for the Space Shuttle.  But that has at least a couple of years of development I would guess.

Done


Done.

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#1869 2024-06-13 19:50:29

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,300

Re: Starship is Go...

When you count reuse the price for a launch will go down and does not have much to do with the build of the ship as its just man hours and fuel for each flight.
Ship lose will cause the price to rise as those costs are not considered in the launch use costs.

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#1870 2024-06-13 20:14:03

Void
Member
Registered: 2011-12-29
Posts: 7,354

Re: Starship is Go...

It is proposed that Starship reuse will require less effort than for the Falcon 9.  And if they can reuse the 2nd stage eventually, that it how they think they might eventually get to $90/kg or even $9/kg.  And of course, they will have a larger fairing size, which could be a selling point to offer customers.

But we will see what is true.

Done

Last edited by Void (2024-06-13 20:14:17)


Done.

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#1871 2024-06-18 13:35:46

RGClark
Member
From: Philadelphia, PA
Registered: 2006-07-05
Posts: 744
Website

Re: Starship is Go...

Human missions to Mars in doubt after astronaut kidney shrinkage revealed
‘An astronaut could make it to Mars but they might need dialysis on the way back,’ scientist warns
https://www.independent.co.uk/space/mar … 61132.html

Why I favor fast Mars flights. With orbital propellant depots can do a Mars trip in one month:

https://exoscientist.blogspot.com/2015/ … etary.html

  Bob Clark


Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):

      “Anything worth doing is worth doing for a billion dollars.”

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#1872 2024-06-18 21:52:15

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,590

Re: Starship is Go...

Dr Clark,

This is just another "snow day".  We already know what the problem is.  It has little or nothing to do with radiation damage.  Human beings, as well as the bodies of all other living things on Earth, were only ever designed to function with the aid of gravity.  When you take away gravity, a lot of bad things start to happen, because millions of years of evolution took place in a high-gravity environment.  We do not have anything approaching a solution to living without gravity, except... artificial gravity.  Human bodies function best with gravity.  Any long duration mission to another planet should include artificial gravity in its list of requirements.

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#1873 2024-06-19 08:15:00

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,609
Website

Re: Starship is Go...

I quite agree with Kbd512:  just avoid most of the medical troubles and do artificial gravity.  It's fairly incompatible with minimalist vehicle design,  but that is the price you must pay to make the long trips. Partial gee at some level is likely "good enough",  and partial daily exposure to zero-gee is likely not much of a problem.  Too bad the experiments have never been done that could tell us how much gee is enough,  and how much of a day we can be at zero-gee and still be healthy.  You have to have some sort of spinning space station to do them!

Radiation in the form of cosmic rays is a canard often used as an excuse not to go,  but it's just that:  a canard,  a lie.  In the inner solar system near Earth,  it varies between 24 and 60 REM/year,  with the solar cycle.  The astronaut exposure limits were set for many years at 50 REM/year,  25 REM in one month,  and lifetime career limit that was age and gender-dependent,  but peaked at 400 REM over a career. These exposure limits were supposed to allow a 3% increase in late-in-life cancers. 

The real radiation danger is flares and mass ejections from the sun.  Those can be as bad as standing outside in the fallout right after a nearby surface burst atomic explosion.  5000 REM/hour class stuff.   They are only hours long,  and are very directional,  occurring very erratically. There are typically more of them during solar peak activity,  as has been happening recently.  This has even been seen by the instruments on Mars.

To "calibrate" these numbers,  consider that 100 REM over a short interval like an hour will give you serious radiation sickness,  300 REM in a short interval will kill about 50% of those so exposed,  and 500 REM over a short interval is lethal to 100% of those so exposed.

GW

Last edited by GW Johnson (2024-06-19 08:20:47)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#1874 2024-06-19 16:12:32

RGClark
Member
From: Philadelphia, PA
Registered: 2006-07-05
Posts: 744
Website

Re: Starship is Go...

The radiation shielding mass can be quite significant. A rough estimate, 150 tons for a 1,000 cu. m. sized Starship payload section, more than the dry mass of the entire Starship:

http://newmars.com/forums/viewtopic.php … 92#p221992

  Bob Clark


Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):

      “Anything worth doing is worth doing for a billion dollars.”

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#1875 2024-06-20 08:49:17

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,609
Website

Re: Starship is Go...

'Starship" is not configured to provide artificial spin gravity or significant radiation protection,  and probably never will be. 

It will be one of the internal spaces just barely large enough for all aboard to crowd into,  that will be the radiation shelter.  With some lightweight polymer-based fibrous insulation installed thick on the walls of only that space,  plus the added effect of the outer wall of the ship,  that should be enough shielding for all but the most violent of solar events to provide survival,  but not safety.

The outer hull wall in all crew spaces will have to be insulated thermally anyway,  so that's two layers of wall and modest-to-thick thermal insulation that constitute the shielding.  It won't be the recommended 20-25 g/cm^2,  but every little bit helps. 

Bigger solar events probably will lead to serious radiation sickness cases.  That would seem to be inevitable,  but with two insulated walls,  you get the effects of two spacecraft hulls,  not just one,  to protect you. 

"One hull" is not enough:  the really-bad 1972 event between Apollo 16 and Apollo 17 would have killed an Apollo crew in only several hours after the end of the exposure,  with only one thin hull's protection,  and that rather thinly insulated. 

GW

Last edited by GW Johnson (2024-06-20 08:56:25)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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