Starship Orbital Test Flight tomorrow morning! (17/4/23)

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Hans Gruber

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Dec 23, 2006
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I consider the launch a success. It did a few flips in the sky and flew up like a roman candle before terminating the flight/rocket in the sky. There is still work to be done but I thought everything went well until the very end.

This is supposed to be more powerful than the Saturn 5 rocket. It didn't look like it. They probably launched with reduced power.
 

Number1

Diamond Member
Feb 24, 2006
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Looks like 6 engines failed. right away.
You can also see the rocket tilt and slide at liftoff. A crater has formed under the launch mount and there was massive amount of debrie flying, some even damaging a van kilometers away.
You can see anomalies in the trust flames as the rocket goes up. Hydraulics that control the gimbling might have failed.
Some of the tanks in the farm have been damaged and are leaking.

It's a wonder it did not just blow! LOL
Fun day
 

[DHT]Osiris

Lifer
Dec 15, 2015
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This is supposed to be more powerful than the Saturn 5 rocket. It didn't look like it. They probably launched with reduced power.
Something I learned from my extensive experience with KSP is that having absolute bonkers power at the launch pad isn't necessarily better. You want the oomph when you clear a fair percentage of the atmosphere so you don't get bogged down.

I'm guessing the first stage on this thing can clear the atmosphere with 80% fuel or less, use the remainder to get the orbit extended, dump the first stage, then use the second stage to clear the Delta v divide to Mars or the belt.
 

Brovane

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Dec 18, 2001
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Something I learned from my extensive experience with KSP is that having absolute bonkers power at the launch pad isn't necessarily better. You want the oomph when you clear a fair percentage of the atmosphere so you don't get bogged down.

I'm guessing the first stage on this thing can clear the atmosphere with 80% fuel or less, use the remainder to get the orbit extended, dump the first stage, then use the second stage to clear the Delta v divide to Mars or the belt.

It is a trade off, you want to launch with something like 1.25-1.5 times you mass in thrust to minimize gravity losses. You want to get as quickly as possible into the upper atmosphere without adding to much mass for additional thrust. With Starship today they lost something like 4-5 engines basically soon after launch and they were a lot closer to 1.25 times or even less on thrust to mass which is why it appeared to be gaining velocity slowly. That was my first indication that something was off, was how slowly the velocity was creeping up. In general liquid powered launch vehicles have lower thrust to mass ratios as compared to vehicles with solids which have a lot of thrust but low ISP (Efficiency) which gives thrust for a shorter amount of time. Checkout these Minotaur launch and compare it to a Falcon-9 leaving the pad.
That rocket really moved quickly off the pad.
 
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crashtech

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Jan 4, 2013
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I watched the launch and thought of the term "successful failure," in that although not all objectives were achieved, much useful data were no doubt collected. It's an expensive way to collect data, to be sure.
 

Hans Gruber

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Dec 23, 2006
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The media is saying they hit the self destruct button after the rocket tumbled a few times. I call that a success for the 1st launch attempt.
 

[DHT]Osiris

Lifer
Dec 15, 2015
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It is a trade off, you want to launch with something like 1.25-1.5 times you mass in thrust to minimize gravity losses. You want to get as quickly as possible into the upper atmosphere without adding to much mass for additional thrust. With Starship today they lost something like 4-5 engines basically soon after launch and they were a lot closer to 1.25 times or even less on thrust to mass which is why it appeared to be gaining velocity slowly. That was my first indication that something was off, was how slowly the velocity was creeping up. In general liquid powered launch vehicles have lower thrust to mass ratios as compared to vehicles with solids which have a lot of thrust but low ISP (Efficiency) which gives thrust for a shorter amount of time. Checkout these Minotaur launch and compare it to a Falcon-9 leaving the pad.
That rocket really moved quickly off the pad.
Right, I just meant you don't want 3x-10x at sea level because you're burning a shitload of fuel and going nowhere any faster. The flight profile for big rockets at 0' is basically identical, the magic happens at 100k+
 

Brovane

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Dec 18, 2001
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Right, I just meant you don't want 3x-10x at sea level because you're burning a shitload of fuel and going nowhere any faster. The flight profile for big rockets at 0' is basically identical, the magic happens at 100k+

Yup, there is a zone you want to stay at, especially if you have astronauts onboard. I remember reading in Michael Collins biography he talked about how much more gentle the Saturn-V was on G-load as compared to the Titan II which had been designed as ICBM and you had 6+ G's. Collins called the Saturn-V gentle because it maxed out at 4G right before staging on the 1st stage. If you look at rocket's trajectory they basically start bending over once you get above 100,000 feet and don't go straight up anymore. At that point it is more about gaining velocity to reach the speed required for orbit than just gaining altitude.

Interesting analysis of the Starship flight. I didn't realize that SpaceX throttled the engines at liftoff so much at liftoff.

Starship Flight Analysis: What went wrong with Starship?
 
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spacejamz

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Photo credit: John Kraus
342041395_1918101235222502_5330001237901229244_n.jpg
 

skyking

Lifer
Nov 21, 2001
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@Brovane thanks for the video. Very informative.
I watched the telemetry at the end replay, and it reached a maximum altitude of 39 km and then flipped it's way on down to 29 km and self destruction.
Cool to have all that and the velocity.
Since everything is kerflooey, it is probably pointless to speculate about FOD taking out those initial engines. The way the crater was excavated It seems like as good a theory as any.
 
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Racan

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Sep 22, 2012
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Interesting post from nasaspaceflight forum

I've waited for several days for the air to clear and more info to become available, but it's time say something.

Frankly, Elon had good people helping him do this for many years. They successfully built him west coast and east coast launchpads. He decided they weren't moving fast enough / were being too "traditional" for Starship and let them go two years ago. I know one very senior engineer manager for him who was pushing for a more traditional flame trench/divertor at BC who Elon got tired of hearing from and fired. This is the result...this one's on Elon, personally, IMHO. People in SpaceX repeatedly warned him the risks of damage from the concrete. The tweet several months ago was his belated acknowledgement that they were probably right, but it was too late at that point, he was committed to the current flat pad at that point.
 

Amused

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Apr 14, 2001
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It boggles my mind that SpaceX didn't design a dampening system on the launch pad. It's like they completely ignored the lessons NASA learned 60 plus years ago.
 

sdifox

No Lifer
Sep 30, 2005
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Elon: See? They have to repair the flame trenches every time they launch. So I am just going to skip building them.
 
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Number1

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Feb 24, 2006
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Wow, the launch pad destroyed, debris flying everywhere, failing engines, starship tilting and sliding as it clears the launch pad, explosions and flames coming out of the side of the booster on ascent, loss of hydraulics and I am certainly missing a few.

It's amazing this thing still managed to fly. It's going to be a safe rocket once perfected.

Who TF designed that launchpad?

Scott Manley with his analysis. "Rapid Unplanned Digging"

 
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MrSquished

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Jan 14, 2013
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Musk's biggest success is when he has enough people around him to mitigate the damage he does by being the egomaniac narcissist he is.
 

Number1

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Feb 24, 2006
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Musk's biggest success is when he has enough people around him to mitigate the damage he does by being the egomaniac narcissist he is.
And after several iterations, he gets it right. As a matter of fact, he surpasses anything that was done before.
Like it or not.
 
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K1052

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Aug 21, 2003
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Seeing all the damage to the pad and other launch infra seems plausible that debris could have damaged the first stage engines.

Musk has a fairly amazing talent for self inflicted wounds.