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Zeppi
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 8:39 pm

Yeah, that was a hefty impact!
 
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flyingturtle
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 8:40 pm

At least the launch pad is now clear

...and SN10 is living in fear.


In other news, Michael Bay is out... there will be Elon Musk films...
Last edited by flyingturtle on Tue Feb 02, 2021 8:50 pm, edited 1 time in total.
Reading accident reports is what calms me down
 
meecrob
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 8:43 pm

You can see a chunk fly off at engine re-light from the engine section.
 
Okie
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 9:37 pm

casinterest wrote:
Looks like only one engine relit. The explosion probably made cleanup a bit easier in terms of size, harder in terms of debris field


That is the design to land using one engine.
You don't use a 20 megaton thermonuclear device to toast a marshmallow. :hot:

There is just not much weight left after you have used up 98% of your fuel load. There is not enough turn down ratio on a raptor to need more than one engine to land.

The problems are elsewhere.

Okie
 
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casinterest
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 9:45 pm

Okie wrote:
casinterest wrote:
Looks like only one engine relit. The explosion probably made cleanup a bit easier in terms of size, harder in terms of debris field


That is the design to land using one engine.
You don't use a 20 megaton thermonuclear device to toast a marshmallow. :hot:

There is just not much weight left after you have used up 98% of your fuel load. There is not enough turn down ratio on a raptor to need more than one engine to land.

The problems are elsewhere.

Okie



I don't think so. SN8 failed because the 2nd engine failed after lighting. The 2nd engine failed to light on SN9 as seen in the spacex stream.
https://youtu.be/_zZ7fIkpBgs?t=697

They may have problems elsewhere as well, but to steady this rocket on the flip, they need two engines.

//edit.-----One engine to land is fine, and we see that it does hover at altitude with one, but one engine can't slow and steady the flip.
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
Okie
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 10:03 pm

casinterest wrote:
I don't think so. SN8 failed because the 2nd engine failed after lighting. The 2nd engine failed to light on SN9 as seen in the spacex stream.
https://youtu.be/_zZ7fIkpBgs?t=697

They may have problems elsewhere as well, but to steady this rocket on the flip, they need two engines.

//edit.-----One engine to land is fine, and we see that it does hover at altitude with one, but one engine can't slow and steady the flip.


If you look closely in the clip you will see a propellant fire near the top of the failed engine shortly after the failure to reignite during the descent. I noticed a bit of flame early in the launch dancing around near the top of the engine compartment on the assent. Most likely due to a propellant pump turbine failure.

Okie
 
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casinterest
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 10:23 pm

Okie wrote:
casinterest wrote:
I don't think so. SN8 failed because the 2nd engine failed after lighting. The 2nd engine failed to light on SN9 as seen in the spacex stream.
https://youtu.be/_zZ7fIkpBgs?t=697

They may have problems elsewhere as well, but to steady this rocket on the flip, they need two engines.

//edit.-----One engine to land is fine, and we see that it does hover at altitude with one, but one engine can't slow and steady the flip.


If you look closely in the clip you will see a propellant fire near the top of the failed engine shortly after the failure to reignite during the descent. I noticed a bit of flame early in the launch dancing around near the top of the engine compartment on the assent. Most likely due to a propellant pump turbine failure.

Okie


I thought the little flames were ok as that was just fumes from the fuel, but perhaps SN9 never got any of the modifications that will go into future rockets to prevent the header tank pressure issue.
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
mxaxai
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 10:35 pm

meecrob wrote:
You can see a chunk fly off at engine re-light from the engine section.

I think that that's just some insulation foil from the ancillary parts that surround the engine. It doesn't look structural and seems to come from the outer part of the cylinder, not the center where the engines are.
There are at least three parts that are lost; one at T+06:20, one at T+06:23 and one at T+06:24 (though that one might remain partially attached). They all look like foil.

Comparing this to SN8: It takes SN8 and SN9 about 4 seconds to flip, i. e. about the same, but it takes SN8 about 11 seconds from engine re-light to impact while SN9 does it in 8 seconds.
It could be that SN9 started the maneuver later, or had a higher terminal velocity, or had more fuel remaining, which didn't leave enough time to stabilize the rocket and stop.

However, I believe there's something wrong with the no. 2 engine. Fuel pump failure, perhaps, or a burst pipe?
We see the first engine ignite and throttle up at T+06:18 and the second engine ignite at T+06:19, then throttle up at T+06:20. Less than a second later, the second engine's exhaust is a dirty brown and much more diffuse compared to the clean, tight exhaust of the first engine. There's a lot of excess fuel being burnt outside of the rocket. By T+06:23, clearly only the no. 1 engine remains operating. Impact is at T+06:26.
Now compare SN8, where the second engine remains on for nearly 8 seconds, a period that contains the entire flip. There are no orange flames, only the clearly defined violet exhaust, except briefly during engine shutdown.
 
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Nomadd
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 11:18 pm

casinterest wrote:
Looks like only one engine relit. The explosion probably made cleanup a bit easier in terms of size, harder in terms of debris field.

There are advantages to that. It gives me more parts to make stuff. This use to be one of SN8's COPVs.
Image
Image
Last edited by Nomadd on Tue Feb 02, 2021 11:32 pm, edited 4 times in total.
 
fsnuffer
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 11:21 pm

mxaxai wrote:
meecrob wrote:
However, I believe there's something wrong with the no. 2 engine. Fuel pump failure, perhaps, or a burst pipe?


Perhaps the flip has an affect sloshing the fuel around.
 
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Nomadd
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 11:25 pm

Okie wrote:
casinterest wrote:
Looks like only one engine relit. The explosion probably made cleanup a bit easier in terms of size, harder in terms of debris field

That is the design to land using one engine.
You don't use a 20 megaton thermonuclear device to toast a marshmallow. :hot:
There is just not much weight left after you have used up 98% of your fuel load. There is not enough turn down ratio on a raptor to need more than one engine to land.
The problems are elsewhere.
Okie

It's suppose to use two engines for the flip right up until it's vertical and steady. You could see both of them scissoring on SN8.
 
ZaphodHarkonnen
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Re: SpaceX - Tests, Launches, Developments - 2021

Tue Feb 02, 2021 11:30 pm

fsnuffer wrote:
mxaxai wrote:
meecrob wrote:
However, I believe there's something wrong with the no. 2 engine. Fuel pump failure, perhaps, or a burst pipe?


Perhaps the flip has an affect sloshing the fuel around.


The header tanks exist to try and deal with that. But yeah, something went wrong and engine failed to light. I expect we'll find out why in the next few days.
 
mxaxai
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 1:22 am

ZaphodHarkonnen wrote:
fsnuffer wrote:
mxaxai wrote:


Perhaps the flip has an affect sloshing the fuel around.


The header tanks exist to try and deal with that. But yeah, something went wrong and engine failed to light. I expect we'll find out why in the next few days.

I don't think it merely failed to light. We see it burn bright, for a second or so. Of course it could be the opposite of SN8, i. e. rather than the methane running out, there wasn't enough O2 supplied, which would shut the engine down. But the way the engine fails looks quite different from SN8, I think they made the necessary changes to not repeat that test.
 
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Nomadd
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 4:10 am

It looks like they're going to try and launch two Starlink missions 4 hours apart. 18 first at 0119 EST on pad 40 and 17 on 39A at 0536 EST Feb 4.
 
aumaverick
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 1:46 pm

Why did SN9's body (1/4 up from base) and nose cone appear to be frosted during the flight? Was there a leak somewhere causing the steel to freeze?
I'm just here so I won't get fined. - Marshawn Lynch
 
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casinterest
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 1:51 pm

aumaverick wrote:
Why did SN9's body (1/4 up from base) and nose cone appear to be frosted during the flight? Was there a leak somewhere causing the steel to freeze?


That is the frozen fuel condensation freezing on the outside. You can see it on the pad as well. There isn't much insulation on starship right now.

Image

https://space.stackexchange.com/questio ... he-vehicle

All the rockets form ice on the pads with the low temperature liquid fuels.
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
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Francoflier
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 2:28 pm

Nomadd wrote:
It looks like they're going to try and launch two Starlink missions 4 hours apart. 18 first at 0119 EST on pad 40 and 17 on 39A at 0536 EST Feb 4.


Do we know why Starlink 17 keeps getting delayed? It was originally scheduled to go up on the 29th...
Though 2 launches a few hours apart would be pretty nice.


Musk has been conspicuously silent about Snine's flight. He's usually a bit more loquacious after their tests, even when they go slightly awry. I think they were expecting a better showing.

Also: it's always seemed strange to me that they built the landing pad so close to the launching pads and cryogenic tank farm... I suppose they're somewhat confident about their accuracy, but it wouldn't have taken much for Snine to take out a bunch of expensive hardware, not to mention its little brother which SpaceX seemingly had no qualms about bringing right to the frontline jut before the test.
In fact, given the amount of shrapnel flying past, I'd be surprised if they don't have to patch up SN10 in a few places. What was the hurry? :confused:
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
Heinkel
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 2:34 pm

Looks like in the current state, that missile is a death trap. Far, far away from being certifiable for human transport.
 
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Tugger
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 2:45 pm

Heinkel wrote:
Looks like in the current state, that missile is a death trap. Far, far away from being certifiable for human transport.

As intended.

The current batch is being iterated for the development of engines and flight and landing processes. Once completed they can move from there and look at launching space hardware, but while doing this there is no need at all to add the massive expense required for human transport. That will only happen once the aforementioned items are understood and reliably repeatable launches and landings are taking place.

Tugg
I don’t know that I am unafraid to be myself, but it is hard to be somebody else. - W. Shatner
There are many kinds of sentences that we think state facts about the world but that are really just expressions of our attitudes. - F. Ramsey
 
Heinkel
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 3:02 pm

Tugger wrote:
Heinkel wrote:
Looks like in the current state, that missile is a death trap. Far, far away from being certifiable for human transport.

As intended.

The current batch is being iterated for the development of engines and flight and landing processes. Once completed they can move from there and look at launching space hardware, but while doing this there is no need at all to add the massive expense required for human transport. That will only happen once the aforementioned items are understood and reliably repeatable launches and landings are taking place.

Tugg


So as Wernher von Braun said some decades ago: Test, test, test...
 
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casinterest
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 4:19 pm

Heinkel wrote:
Tugger wrote:
Heinkel wrote:
Looks like in the current state, that missile is a death trap. Far, far away from being certifiable for human transport.

As intended.

The current batch is being iterated for the development of engines and flight and landing processes. Once completed they can move from there and look at launching space hardware, but while doing this there is no need at all to add the massive expense required for human transport. That will only happen once the aforementioned items are understood and reliably repeatable launches and landings are taking place.

Tugg


So as Wernher von Braun said some decades ago: Test, test, test...



At least we are getting some spectacular crash footage for future montages.
https://www.youtube.com/watch?v=Ep8XJanoFgw
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
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Tugger
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 5:26 pm

Someone needs to do a side-by-side video of the two flip-transitions and landings. To show the differences between SN8 and SN9. That "from below" view is pretty awesome.

Tugg
I don’t know that I am unafraid to be myself, but it is hard to be somebody else. - W. Shatner
There are many kinds of sentences that we think state facts about the world but that are really just expressions of our attitudes. - F. Ramsey
 
mxaxai
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 5:37 pm

casinterest wrote:
aumaverick wrote:
Why did SN9's body (1/4 up from base) and nose cone appear to be frosted during the flight? Was there a leak somewhere causing the steel to freeze?


All the rockets form ice on the pads with the low temperature liquid fuels.

The white cloud after impact shows that the LO2 header tank was not empty, in my opinion. Since O2 does not burn without a fuel, spilled O2 only makes the water vapor in the air condense (or freeze) and form clouds. The distance between the LO2 header tank and the methane tank ensured that the methane did not mix much with the header tank's O2 after disintegration.
 
FGITD
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 5:46 pm

Nomadd wrote:
It looks like they're going to try and launch two Starlink missions 4 hours apart. 18 first at 0119 EST on pad 40 and 17 on 39A at 0536 EST Feb 4.


Apparently it will be the narrowest gap between launches in the US since Gemini 12. I wonder how far apart the drone ships will be.

SN9 seemed to go relatively well. While the most discussed and exciting part is the explosion/landing, I get the impression that it’s not really the flight aspect being fully tested at the moment. It seems more like the launch and in flight maneuvering is what they’re really looking into, followed by how everything reacts to being flipped and then flipped back over. I think everyone was a little spoiled by just how close sn8 looked to landing, when that wasn’t expected at all. Personally I’d wager a few more SNs will come down sn9 style in the near future, before finally managing anything closer to sn8 again.

At any rate, roll on sn10! Gotta love the pace at which they test, no 15 month investigations etc etc
 
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casinterest
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 6:41 pm

mxaxai wrote:
casinterest wrote:
aumaverick wrote:
Why did SN9's body (1/4 up from base) and nose cone appear to be frosted during the flight? Was there a leak somewhere causing the steel to freeze?


All the rockets form ice on the pads with the low temperature liquid fuels.

The white cloud after impact shows that the LO2 header tank was not empty, in my opinion. Since O2 does not burn without a fuel, spilled O2 only makes the water vapor in the air condense (or freeze) and form clouds. The distance between the LO2 header tank and the methane tank ensured that the methane did not mix much with the header tank's O2 after disintegration.



No one ever said the tanks were empty, but they were rather close to it. The crash is probably either a lighting issue on engine 2 or a fuel feed issue caused by the header tank, or the fuel pump.
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
mxaxai
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 8:14 pm

casinterest wrote:
No one ever said the tanks were empty, but they were rather close to it. The crash is probably either a lighting issue on engine 2 or a fuel feed issue caused by the header tank, or the fuel pump.

I don't disagree.
 
ThePointblank
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 8:43 pm

casinterest wrote:
mxaxai wrote:
casinterest wrote:

All the rockets form ice on the pads with the low temperature liquid fuels.

The white cloud after impact shows that the LO2 header tank was not empty, in my opinion. Since O2 does not burn without a fuel, spilled O2 only makes the water vapor in the air condense (or freeze) and form clouds. The distance between the LO2 header tank and the methane tank ensured that the methane did not mix much with the header tank's O2 after disintegration.



No one ever said the tanks were empty, but they were rather close to it. The crash is probably either a lighting issue on engine 2 or a fuel feed issue caused by the header tank, or the fuel pump.


If you look at the video, during the flip and descent, engine 2 spits out something and fails to light. Possible engine malfunction?
Last edited by ThePointblank on Wed Feb 03, 2021 8:44 pm, edited 1 time in total.
 
GDB
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 8:43 pm

 
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casinterest
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 8:52 pm

ThePointblank wrote:
If you look at the video, during the flip and descent, engine 2 spits out something and fails to light. Possible engine malfunction?


GDB wrote:


Scott may be onto something with the idea that there was a void in the line, it may have destroyed part of the pump. I initially though that was ice, but those do look like parts breaking .

I like the "hey SN10....don't do that" :
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
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Nomadd
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Re: SpaceX - Tests, Launches, Developments - 2021

Wed Feb 03, 2021 9:25 pm

They've always known that modelling the fuel flow while this thing is flipping around and lighting engines would be the biggest unknown. Nobody has ever done anything like it before. The first DIV Heavy failed because of a simple elbow. Getting fuel to all the right places at needed pressures with no gas bubbles during all the acrobatics is about a hundred times as complicated.
 
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Francoflier
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Re: SpaceX - Tests, Launches, Developments - 2021

Thu Feb 04, 2021 6:48 am

Starlink launch #17 keeps getting delayed, scheduled for tomorrow now, which means that Starlink L18 launched just now ahead of it...
Another nominal mission with B1060 back on the barge after its 5th duty. The space mind-control devices are on their way to bring Musk's plan for World domination closer to fruition.

I wonder what's going on with the other rocket, since it's obviously not a weather delay... L17 is using B1049, the oldest Block 5 booster still alive, so I hope they're not encountering issues with it.

Edit:
Here's more light on why the FAA was miffed after SN8's launch:
https://spacenews.com/spacex-violated-l ... n8-launch/

SN9's fireworks display will likely not make the FAA any less stingy with the launch permits...
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
memphiX
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Re: SpaceX - Tests, Launches, Developments - 2021

Thu Feb 04, 2021 2:53 pm

May be they should try to flip it at 3 km or higher next time? Do they have anti-slosh baffles in the tanks?
 
meecrob
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Re: SpaceX - Tests, Launches, Developments - 2021

Thu Feb 04, 2021 3:39 pm

memphiX wrote:
May be they should try to flip it at 3 km or higher next time? Do they have anti-slosh baffles in the tanks?


I've seen this sentiment here and at many other sites, and one has to remember that this is a test program. That means that they have set goals and are developing their hardware to meet those goals. They do NOT just "fly what they got" and alter their goals to fit the prototype vehicle's limitations. Their goal is to be fuel efficient, which means a late flip. Unless they hit a wall somewhere, they are going to develop the fuel system/engines rather than modify the descent profile.
 
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casinterest
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Re: SpaceX - Tests, Launches, Developments - 2021

Thu Feb 04, 2021 5:58 pm

Nomadd wrote:
They've always known that modelling the fuel flow while this thing is flipping around and lighting engines would be the biggest unknown. Nobody has ever done anything like it before. The first DIV Heavy failed because of a simple elbow. Getting fuel to all the right places at needed pressures with no gas bubbles during all the acrobatics is about a hundred times as complicated.



I went back and looked at the feed. It could be cameras, but I think at this point. Engine 2 was undergoing RUD.

https://youtu.be/_zZ7fIkpBgs?t=708

You may have to pause it to see,
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
Okie
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Re: SpaceX - Tests, Launches, Developments - 2021

Thu Feb 04, 2021 8:12 pm

If we consider SN9 had two Raptor failures on test fire and one in flight that is looking at 60% failure rate.

They have stepped up the Raptors output continuously since inception. While I have no idea what output rating they were using on SN9, the concept that they have taken from 200bar chamber pressure to 300bar and now 330 bar may be a half step too far.

Francoflier wrote:
SN9's fireworks display will likely not make the FAA any less stingy with the launch permits...


My thought is that Musk will maybe repurpose either Ensco 8500 or Ensco 8501 semi-submersible drilling rigs (aka Deimos and Phobos) to a test pad to avoid FAA scrutiny instead of his original launch platform plans for the Mars launch vehicles. Not sure he could modify one that quickly but gets FAA out of the picture for surface areas around the launch.

Okie
 
texl1649
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Re: SpaceX - Tests, Launches, Developments - 2021

Thu Feb 04, 2021 10:43 pm

Okie wrote:
If we consider SN9 had two Raptor failures on test fire and one in flight that is looking at 60% failure rate.

They have stepped up the Raptors output continuously since inception. While I have no idea what output rating they were using on SN9, the concept that they have taken from 200bar chamber pressure to 300bar and now 330 bar may be a half step too far.

Francoflier wrote:
SN9's fireworks display will likely not make the FAA any less stingy with the launch permits...


My thought is that Musk will maybe repurpose either Ensco 8500 or Ensco 8501 semi-submersible drilling rigs (aka Deimos and Phobos) to a test pad to avoid FAA scrutiny instead of his original launch platform plans for the Mars launch vehicles. Not sure he could modify one that quickly but gets FAA out of the picture for surface areas around the launch.

Okie


Modifying a half billion dollar rig to float out to sea with a starship (or starship super heavy) on it isn’t going to be cheap or fast. It will take time and will happen in plain view of drones/cameras. The cheaper/faster answer is to use hydrogolics for now to steer the starship into vertical and then light the raptors, but this would mean a temporary design that has to then be changed once mature for Martian exploration (manned).

Frankly, it seems like starship is finally running on a tight budget. Why else put SN10 on the pad for launch/landing (making it appear rushed), light only 2 engines (needing both to work perfectly within a second or 2), press so much for the timeline from FAA etc. I think we are seeing some indications of financial stress, but hope not.
 
Okie
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Re: SpaceX - Tests, Launches, Developments - 2021

Thu Feb 04, 2021 11:44 pm

texl1649 wrote:
Modifying a half billion dollar rig to float out to sea with a starship (or starship super heavy) on it isn’t going to be cheap or fast. It will take time and will happen in plain view of drones/cameras. The cheaper/faster answer is to use hydrogolics for now to steer the starship into vertical and then light the raptors, but this would mean a temporary design that has to then be changed once mature for Martian exploration (manned)


Musk paid only $3.5M each for those two semi-submersibles that left the construction site 10yrs ago for $300M each. I really don't think it would take very long to modify for temporary use. Obviously longer for the desired use. Those were 25,750kw rigs.

I think you mean hypergolics but they bring a major environment issue for humans especially if released around a crash site. That is nasty stuff.

texl1649 wrote:
Frankly, it seems like starship is finally running on a tight budget. Why else put SN10 on the pad for launch/landing (making it appear rushed), light only 2 engines (needing both to work perfectly within a second or 2), press so much for the timeline from FAA etc. I think we are seeing some indications of financial stress, but hope not.


I think you are used to government pace vs private.
I will have to agree that SN10 is on the pad without engines and no affirmative cause of SN9 failure. It may have to go back to assembly for modifications.

Okie
 
iamlucky13
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Re: SpaceX - Tests, Launches, Developments - 2021

Thu Feb 04, 2021 11:56 pm

meecrob wrote:
memphiX wrote:
May be they should try to flip it at 3 km or higher next time? Do they have anti-slosh baffles in the tanks?


I've seen this sentiment here and at many other sites, and one has to remember that this is a test program. That means that they have set goals and are developing their hardware to meet those goals. They do NOT just "fly what they got" and alter their goals to fit the prototype vehicle's limitations. Their goal is to be fuel efficient, which means a late flip. Unless they hit a wall somewhere, they are going to develop the fuel system/engines rather than modify the descent profile.


A test program does not need to accomplish everything at once. I was surprised they planned from the start to have minimal margin for landing, even if it wasn't a primary test goal.They could start with using their fins or RCS to re-orient so that drag settles the ullage like on Falcon, or just use old-school ullage motors. With the Grasshoppers, they tried progressively more difficult tests, and saved some of the highest risk tests until they'd accomplished a litany of other tests. I have to think they could have gotten a lot more productive use out of both SN8 and SN9 if they had the opportunity to fly them multiple times. Then test horizontal restarts with no engine-out margin once all the lower risk tests are complete.

Francoflier wrote:
SN9's fireworks display will likely not make the FAA any less stingy with the launch permits...


Nor should it. Their rocket failures have had generally contained effects so far, but it's not guaranteed that every test failure will result in minimal deviation from the planned trajectory. Since we're talking about a barrel of flammable liquid the size of a small skyscraper being flung miles into the sky only a couple miles from people's homes, the scale of what should be considered reasonably conceivable risks is pretty big.

I could not believe his tweet criticizing the FAA last week. First of all, it was off-base. There's no shortage of requirements for experimental flights of uncertified commercial aircraft. And I think most of us whose jobs are tied to commercial aviation know that we don't get to set deadlines for the FAA. We can also all guess how well open contempt for our regulator would go over. If they are stalling unreasonably, concerns should first be raised directly with the agency, and escalated within, then move to the courts. That is both the respectful and the effective way to deal with such problems.

Secondly, he was complaining about a couple days of delay while they review plans for a launch similar to one that ended badly last time. I think it's great that Musk is fine with the business risks of test failures, but his impatience with safety review requirements is puerile and concerning.

Third, the suggestion that space launch vehicle flights, especially test flights involving return to land are ready for a more laissez-faire regulatory era stands in rather stark contrast the 100 meter diameter fireball he followed the comment up with.

I'm really enjoying watching SpaceX try difficult things and gradually figure out how to make them work, and I give Musk credit for enabling them to do that, but he really needs to cut out the rhetoric and grow up.
 
FGITD
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 3:53 am

Few interesting tweets from Musk today.

Apparently the Falcon 9 landing very early this morning was done in heavier seas and high winds. Impressively it still pretty much landed on the mark. I never really considered that the high use boosters could be used (if the situation presents itself) to test the outer edge of the landing envelope.

Also a slightly funnier response, when asked why they didn’t light all 3 engines on sn9 then throttle one down, he simply said “we were too dumb” and seemed to confirm that for sn10 they will try to relight all 3 then shut one down. Definitely an interesting new approach, looking forward to seeing it.

I also don’t put too much stock in the idea that they’re rushing due to finances. I’d say sn10 was out there because it was ready to move outside, and they needed space in the high bay. If damaged they could have either repaired or cannibalize it for whichever sn is earliest in production. Remember these aren’t the NASA style clean room production floors where not even a stray hair is allowed.. They’re literally welding together rockets in what amounts to a big shed. I mean...SN9 fell over and they still launched it.
 
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Francoflier
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 4:16 am

FGITD wrote:
Few interesting tweets from Musk today.

Apparently the Falcon 9 landing very early this morning was done in heavier seas and high winds. Impressively it still pretty much landed on the mark. I never really considered that the high use boosters could be used (if the situation presents itself) to test the outer edge of the landing envelope.

Also a slightly funnier response, when asked why they didn’t light all 3 engines on sn9 then throttle one down, he simply said “we were too dumb” and seemed to confirm that for sn10 they will try to relight all 3 then shut one down. Definitely an interesting new approach, looking forward to seeing it.

I also don’t put too much stock in the idea that they’re rushing due to finances. I’d say sn10 was out there because it was ready to move outside, and they needed space in the high bay. If damaged they could have either repaired or cannibalize it for whichever sn is earliest in production. Remember these aren’t the NASA style clean room production floors where not even a stray hair is allowed.. They’re literally welding together rockets in what amounts to a big shed. I mean...SN9 fell over and they still launched it.


B1060 is not really a 'high use' booster now - at least by SpaceX standard - given it was 'only' its 5th flight and fleet leaders are sitting at 8 and 7, and counting.
I think the conditions were what they were, and rather than delaying the launch, they just went for it to see what happened. I still believe they were reasonably confident as they can't really afford to lose too many boosters given the busy schedule this year.
I also think they would rather have done it with B1049 which should have launched first but, for some reason, keeps getting delayed.

Interestingly, and not happy with acing the landing in very rough seas, B1060 broke the record for booster turnaround time with only 27 days between the last 2 launches... F9 keeps piling on the impressive accomplishments. What a program.


As for SN9, I think the twitter discussion Musk was having with a few enthusiasts was more along the lines of starting all 3 engines for redundancy then, if they all start successfully, immediately shutting down the least healthy/useful one as the Raptor can't be throttled low enough for a 3 engine landing.
That was indeed dumb that they didn't think of that, especially given the issues they've seemingly been having with Raptors lately and since it could probably easily be software-implemented.
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Nomadd
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 6:11 am

If the problem is still clean fuel delivery at acceptable pressures, starting all three would make it worse. They're being unusually quiet about the cause.
 
CRJockey
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 8:14 am

Francoflier wrote:
As for SN9, I think the twitter discussion Musk was having with a few enthusiasts was more along the lines of starting all 3 engines for redundancy then, if they all start successfully, immediately shutting down the least healthy/useful one as the Raptor can't be throttled low enough for a 3 engine landing.
That was indeed dumb that they didn't think of that, especially given the issues they've seemingly been having with Raptors lately and since it could probably easily be software-implemented.


How do I have to imagine the trajectory for a three engine start in the landing sequence? Up again? Stationary? Wobbling?
 
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flyingturtle
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 9:05 am

Another idea would be using a little drogue parachute to help pointing flamey end down...
Reading accident reports is what calms me down
 
tommy1808
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 9:51 am

flyingturtle wrote:
Another idea would be using a little drogue parachute to help pointing flamey end down...


That would be somewhat more difficult on Mars and impossible on the Moon though.

best regards
Thomas
Well, there is prophecy in the bible after all: 2 Timothy 3:1-6
 
mxaxai
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 11:39 am

tommy1808 wrote:
flyingturtle wrote:
Another idea would be using a little drogue parachute to help pointing flamey end down...


That would be somewhat more difficult on Mars and impossible on the Moon though.

best regards
Thomas

Some missiles have a small booster on the nose cone to tip them over after launch. Cold gas thrusters might work too.

I don't think the flip is the difficult part by itself, though. The real challenge is the fuel sloshing around in nearly empty tanks.
 
tommy1808
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 12:02 pm

mxaxai wrote:
tommy1808 wrote:
flyingturtle wrote:
Another idea would be using a little drogue parachute to help pointing flamey end down...


That would be somewhat more difficult on Mars and impossible on the Moon though.

best regards
Thomas

Cold gas thrusters might work too.


i think they already have those, but cold gas is horribly inefficient and once aerodynamic forces are involved that stuff gets heavy.

I don't think the flip is the difficult part by itself, though.


me neither

The real challenge is the fuel sloshing around in nearly empty tanks.


:checkmark:
And providing fuel to the engines without much in the way of gas bubbles disintegrating the turbo pumps ...

best regards
Thomas
Well, there is prophecy in the bible after all: 2 Timothy 3:1-6
 
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flyingturtle
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 12:26 pm

tommy1808 wrote:
flyingturtle wrote:
Another idea would be using a little drogue parachute to help pointing flamey end down...


That would be somewhat more difficult on Mars and impossible on the Moon though.


Oh yes, my idea is pretty stupid. It would only help in earthly testing...
Reading accident reports is what calms me down
 
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casinterest
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 2:10 pm

I wonder if Spacex sees the issue as a software problem instead of hardware. Maybe they are missing something in the timing of the engines and pressure of the system when they are staggering the ignitions.

As for having SN10 on the pad, that was due to the delays in SN9. By all measurements SN11 is getting ready to be stacked up.
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
meecrob
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 2:42 pm

iamlucky13 wrote:
meecrob wrote:
memphiX wrote:
May be they should try to flip it at 3 km or higher next time? Do they have anti-slosh baffles in the tanks?


I've seen this sentiment here and at many other sites, and one has to remember that this is a test program. That means that they have set goals and are developing their hardware to meet those goals. They do NOT just "fly what they got" and alter their goals to fit the prototype vehicle's limitations. Their goal is to be fuel efficient, which means a late flip. Unless they hit a wall somewhere, they are going to develop the fuel system/engines rather than modify the descent profile.


A test program does not need to accomplish everything at once. I was surprised they planned from the start to have minimal margin for landing, even if it wasn't a primary test goal.They could start with using their fins or RCS to re-orient so that drag settles the ullage like on Falcon, or just use old-school ullage motors. With the Grasshoppers, they tried progressively more difficult tests, and saved some of the highest risk tests until they'd accomplished a litany of other tests. I have to think they could have gotten a lot more productive use out of both SN8 and SN9 if they had the opportunity to fly them multiple times. Then test horizontal restarts with no engine-out margin once all the lower risk tests are complete.


This is exactly why I posted my previous reply. Your solution is to alter the flightpath and sequence of events to accommodate for hardware/software that still requires development. This will possibly save some prototype vehicles from crashing at the expense of gaining useless landing information that cannot be used elsewhere because you altered the profile. Clearly SpaceX is approaching this problem from the aspect of "let's just build enough prototypes it doesn't matter if they crash." In general in flight test, you alter the prototype to fit the design criteria, you do not alter the design criteria to fit your prototype, unless there is a change somewhere else, like funding, or timeline.
 
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Tugger
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Re: SpaceX - Tests, Launches, Developments - 2021

Fri Feb 05, 2021 4:57 pm

Nomadd wrote:
If the problem is still clean fuel delivery at acceptable pressures, starting all three would make it worse. They're being unusually quiet about the cause.

.
mxaxai wrote:
I don't think the flip is the difficult part by itself, though. The real challenge is the fuel sloshing around in nearly empty tanks.

.
Put a hinged disk inside the landing tanks with a pressure bladder on one side. When the tanks are full the disk is folded "up", both halves flat together taking little volume with the the deflated bladder in between. When needed inflate the bladder forcing the fuel down toward the delivery tube port and keep inflating as it is used continuing to force the fuel where it is needed and keeping the fuel line full.

I dunno, probably overly simplistic or complex. Just thinking how to ensure the fuel has no empty volume/space in which to slosh around and not be where it needs to be. That the vessels are round at least make a simple hinged disk an idea.

Tugg
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