Starship is Go...

SpaceNut · 2020-12-08 20:22:03

GW this does not look good with the venting...

Elon Musk, who founded SpaceX in 2002, had previously estimated a 2-in-3 chance that the test flight would fail. Musk said last week that a "lot of things need to go right" for the prototype, called Starship serial no. 8, or SN8, to land intact.

This is also the first time I am seeing this artwork of the total rocket assembly

tahanson43206 · 2020-12-09 08:06:43

The news as of this morning is that the engines shut down in the last seconds of the count down.

The report indicated that SpaceX is (provisionally) thinking of trying again today (Wednesday).

(th)

Void · 2020-12-09 17:12:17

Actually they just did it, as I am sure other people know.

It looked pretty good, although the engines shut down one at a time towards the apex. That may have been by plan, I don't know.

The drop and also the orientation to land looked very good, but they did RUD on landing. It seemed very close though, they almost seem to have landed it.

I am sure the data obtained will be very useful for SN9.

https://www.bing.com/videos/search?q=Sp … M%3DHDRSC3

Of course, as we might expect, the news media will focus on the final crash, and not the level of success.

This is a bit better I think.
https://www.bing.com/videos/search?q=SN … M%3DHDRSC3

Done.

Last edited by Void (2020-12-09 17:18:38)

Void · 2020-12-09 18:24:46

I believe I read that Elon Musk indicated that the fuel header tank pressure was low, so I guess that might be an item they will try to address in the future.

Have to admit I am fairly excited about this. It is an improvement. When I was the most sick, lately I lost interest in Mars and females. I seem to be recovering. Insanity returns

Done.

Last edited by Void (2020-12-09 18:25:09)

RobertDyck · 2020-12-09 19:25:16

Would have been nice if it landed in once piece. Remember, this is supposed to carry passengers. They got Falcon 9 to land in once piece. Starhopper landed successfully several times. To be blunt, I expected this one to as well. As long as everything else worked, landing was supposed to be something they got to work already.

louis · 2020-12-09 19:26:54

No I hadn't seen it!

I think maybe that's the most awesome rocket flight I've ever seen! OK, it fouled up at the end but that used to happen
to F9s all the time and they got it fixed eventually.

Thanks!

Void wrote:

Actually they just did it, as I am sure other people know.
It looked pretty good, although the engines shut down one at a time towards the apex. That may have been by plan, I don't know.
The drop and also the orientation to land looked very good, but they did RUD on landing. It seemed very close though, they almost seem to have landed it.
I am sure the data obtained will be very useful for SN9.
https://www.bing.com/videos/search?q=Sp … M%3DHDRSC3
Of course, as we might expect, the news media will focus on the final crash, and not the level of success.
This is a bit better I think.
https://www.bing.com/videos/search?q=SN … M%3DHDRSC3
Done.

SpaceNut · 2020-12-09 19:35:32

Thanks Void for the video links as I watched them on the cellphone and it worked real well.

The first engine that went out banged the others heavily causing damage as it continued to leak fuel all the way to the peak of the ships trip upward. With flame catching to the internal matting a few times. The second engine seemed to shutoff as required with the final one stopping just prior to the nose tail spin for the glide which looked quite good but the camera shows one fin stable while the other is walking about quite a bit.

You could see that the flame as it rose upward contained excess fuel along the way after the first engine went out.

When the engines come back on it seems like it waited way to long as it took quite a bit of time to get it back to the nose up orientation leaving less time for the final descent to the ground which seemed to be to quick as it landed real hard.

GW Johnson · 2020-12-09 20:01:05

Well, look at what they accomplished.

The flight was supposed to demonstrate controlled 3 engine-or-fewer flight to an altitude. It did that rather well, shutting down to 2 then 1 engines on the way up! Remember, it CANNOT fly at a full fuel load! There is only 6 MN thrust available from 3 engines, maximum. My sense was that they launched at something between 1.1 to 1.2 thrust/weight ratio, but I could easily be wrong about that detail. But if I am right, they launched a 120 metric ton airframe with 0 payload and somewhere around 412 tons of payload on board, out of a 1200 ton tank capacity. There should be something like 10-20 tons of propellant still on board for the touchdown, at the apogee shutdown.

The flight was supposed to demonstrate aerodynamic control into a stable "belly-flop" descent with the tail wings and the canard fins. It did exactly that! Did you notice the variable rake angle of the canards and wings during the descent? That reflects active control, real-time. It was very successful.

The flight was supposed to demonstrate engine relight and thrust vector control to achieve tail-first vertical attitude for landing. It looks to me like it did it, or at least mostly. I dunno how much attitude control is also afforded by attitude control thrusters (likely cold gas). I was a tad concerned by the off-vertical attitude angle in the terminal descent toward touchdown. But all-in-all, it looked like this goal was achieved.

The flight was supposed to demonstrate touchdown at essentially zero speed in a vertical attitude, so that the landing legs would be stressed within limits, and fairly evenly distributed among them. This is where it failed: it was still moving on the order of 30-60 m/s downward at impact, and it was around 5-10 degrees off vertical.

Touchdown weight should have been under 1.2-1.3 MN, so that 1 engine could handle it at 60-65% thrust, and two should handle it at 30-33% thrust. But, they didn't! There is the tweet saying the header tank pressure was low upon touchdown. That might explain low thrust, in turn failing to control descent speed. I'm not at all sure where the off-angle attitude at touchdown derives from. But that literally crumples the landing leg that strikes first.

All-in-all, I think the attitude angle error would have toppled and destroyed the test vehicle, regardless of whether the velocity error was zero or not. But the velocity error simply guaranteed an explosion.

Of the two, the attitude may be the more serious problem to resolve. Although, the early Falcon booster recovery failures are remarkable more for velocity error than attitude angle error. They have a lot of work to do to resolve this.

Net score: 3 of 4 overall goals demonstrated successfully in the very first test of this type. 75% success! I'd say that's really, really good!

Remember, this is EARLY in a test effort that is going to require lots of flights, and likely will produce some more spectacular explosions. Such is the nature of rocket test flight work. Take it from me, I know. I used to do this sort of thing.

GW

Last edited by GW Johnson (2020-12-09 20:03:01)

SpaceNut · 2020-12-09 20:20:14

Nice round up GW and for louis yes they will focus on the landin explosion but thats because they like fireworks....

For those that focus on the landing
SpaceX test rocket soars miles into Texas sky, explodes in landing

For those that focus on the achievement
'Mars, here we come!!': SpaceX's Starship prototype performs never-before-seen 'belly flop' during Texas test launch

What is funny is that we ran the simulators for a mars landing and showed that it was the only way to land the tonnage of the ship plus payloads about a year or better....

SpaceNut · 2020-12-11 20:11:03

Satellite images show the charred remains of SpaceX's Starship rocket prototype, after a successful test launch ended in explosion

BB1bRfqc.img?h=599&w=799&m=6&q=60&o=f&l=f

The blast waves also caused the sn9 to tilt into the wall.

BB1bRiky.img?h=1024&w=768&m=6&q=60&o=f&l=f

louis · 2020-12-11 21:32:12

GW, you give a more technical explanatoon of why this has to be considered a major step forward.

GW Johnson wrote:

Well, look at what they accomplished.
The flight was supposed to demonstrate controlled 3 engine-or-fewer flight to an altitude. It did that rather well, shutting down to 2 then 1 engines on the way up! Remember, it CANNOT fly at a full fuel load! There is only 6 MN thrust available from 3 engines, maximum. My sense was that they launched at something between 1.1 to 1.2 thrust/weight ratio, but I could easily be wrong about that detail. But if I am right, they launched a 120 metric ton airframe with 0 payload and somewhere around 412 tons of payload on board, out of a 1200 ton tank capacity. There should be something like 10-20 tons of propellant still on board for the touchdown, at the apogee shutdown.
The flight was supposed to demonstrate aerodynamic control into a stable "belly-flop" descent with the tail wings and the canard fins. It did exactly that! Did you notice the variable rake angle of the canards and wings during the descent? That reflects active control, real-time. It was very successful.
The flight was supposed to demonstrate engine relight and thrust vector control to achieve tail-first vertical attitude for landing. It looks to me like it did it, or at least mostly. I dunno how much attitude control is also afforded by attitude control thrusters (likely cold gas). I was a tad concerned by the off-vertical attitude angle in the terminal descent toward touchdown. But all-in-all, it looked like this goal was achieved.
The flight was supposed to demonstrate touchdown at essentially zero speed in a vertical attitude, so that the landing legs would be stressed within limits, and fairly evenly distributed among them. This is where it failed: it was still moving on the order of 30-60 m/s downward at impact, and it was around 5-10 degrees off vertical.
Touchdown weight should have been under 1.2-1.3 MN, so that 1 engine could handle it at 60-65% thrust, and two should handle it at 30-33% thrust. But, they didn't! There is the tweet saying the header tank pressure was low upon touchdown. That might explain low thrust, in turn failing to control descent speed. I'm not at all sure where the off-angle attitude at touchdown derives from. But that literally crumples the landing leg that strikes first.
All-in-all, I think the attitude angle error would have toppled and destroyed the test vehicle, regardless of whether the velocity error was zero or not. But the velocity error simply guaranteed an explosion.
Of the two, the attitude may be the more serious problem to resolve. Although, the early Falcon booster recovery failures are remarkable more for velocity error than attitude angle error. They have a lot of work to do to resolve this.
Net score: 3 of 4 overall goals demonstrated successfully in the very first test of this type. 75% success! I'd say that's really, really good!
Remember, this is EARLY in a test effort that is going to require lots of flights, and likely will produce some more spectacular explosions. Such is the nature of rocket test flight work. Take it from me, I know. I used to do this sort of thing.
GW

Oldfart1939 · 2020-12-11 23:43:41

Just another point of interest here: Elon is moving from California to Texas.

Tmcom · 2020-12-12 02:16:31

Oldfart1939 wrote:

Just another point of interest here: Elon is moving from California to Texas.

California is crazy, and Musk doesn't want to get the jab, so is understandably doing a runner.

Haven't heard from M-Albion for a month, but since he lives in California he and his family may have done likewise?

kbd512 · 2020-12-12 02:49:27

It would've been better to recover the vehicle to examine it for signs of stress failures from the maneuvers performed, but the actual test was successful, so I don't understand why everyone's going bananas over what happened to the test vehicle after the test was completed. Test articles are, by nature, throwaway items. NASA's plan is to deep six hardware that's at least a couple of orders of magnitude more expensive after each flight, so SpaceX trashing a cheaply made tin can is a complete non-event. That's part of the reason why development and testing is so darned expensive. Sooner or later, they need to invest in robotic friction stir welding equipment and jigs to produce flight quality propellant tanks.

There does seem to be a certain "method to the madness" (build a test article, then test it to destruction- the only way you truly "know your limits"), yet I think my admonishment about the ultimate solution being proper tank design and construction is, more or less, on target. Anything marginally less than perfect isn't going to orbit, much less coming back in one piece, but rapid reuse is supposed to be the goal. I find SpaceX's "fly it like you stole it" attitude towards testing to be a breath of fresh air. It's more like testing used to be in the 1950s and 1960s and less like confirmation bias of the 1970s onwards, which seems to be the attitude towards testing amongst "old space" and NASA.

GW Johnson · 2020-12-12 12:10:22

I am leaning toward the ascent engine shutdowns having been unintentional, because the reported altitude (near 40 kft) is a lot less than the 60 kft that was talked about before the flight.

I'm not exactly sure, but it looked like only two engines were running to do the thrust-vector pitching from belly-flop to tail-first. And one of them looked like its exhaust plume was smoky. Which is very unusual for the Raptor engine.

It also appeared that only two engines were running during the final touchdown. Those plumes were very smoky, and the flame had gone bright green, instead of the normal bluish-purple far from the exit plane (it's only reddish right near the exit plane). Green in any tailpipe flame often means there are copper-bearing particulates in the exhaust stream. Those burn slow, and they burn bright green like that. Wear particles? Debris from some sort of damage or overheating? Who knows?

Now, as a best guess, if they suffered early shutdowns, they would not have burned all the propellant they intended to burn during the flight. That would make them heavy at landing, by multiple tons of unused propellant. And, if you are short on thrust by having one engine out, and at least one of the other two malfunctioning, there is almost no way to zero-out the vertical velocity as you touch down. Plus, this thing was out-of-line vertically by around 5-10 degrees at touchdown.

And, I didn't see any landing legs in any of the photography. Intentional? Unintentional? Who knows?

But as I said in the earlier posting: it was a controlled ascent, and they controlled its peak into the belly flop. It was a well-controlled belly-flop. Even with engines malfunctioning, they got it to the tail-first attitude, more-or-less. Only the touchdown itself failed. Musk said they had troubles with fuel tank pressure in the fuel header tank. And he also said they got lots of good data.

All in all, that's a pretty good first test result, especially for such a highly experimental test of a one-of-a-kind design. Recovering the test article at all would just be the gravy on the steak-and-potatoes.

GW

PS -- Musk is moving to Texas because he is building a Tesla motors plant somewhere around Austin. Plus he has two big test sites in Texas for his Spacex operation. Everything that flies from Canaveral, Vandenburg, or Boca Chica still gets test-fired on the ground at McGregor. I hear it every day. Multiple times a day. My front porch is just about 6 miles line-of-sight from their test stands.

PPS -- Assuming 120 metric tons inert mass, zero payload, and 412 metric tons of propellant, liftoff mass was 532 metric tons, for a weight to be lifted of 5.22 MN. The sea level Raptor is rated at max 2 MN thrust, and can be throttled down to 20%. 3 engines at max thrust setting is 6 MN, of which 6 - 5.22 = 0.78 MN is the net force accelerating the weight upward. That's about 0.15 gees upward, which matches VERY VERY well with the liftoff observations. 491-492 tons of propellant on board, and it would have just sat there, unable to move, at weight equal to or greater than, thrust. This is a sensitive issue, and an engine-out before enough propellant had been burned off would have stopped the ascent entirely.

Last edited by GW Johnson (2020-12-12 12:23:08)

SpaceNut · 2020-12-12 16:19:52

We all love fireworks and thats what we all got when it did not land and its no big deal with a build and launch test premise.

I did not notice and gimbal of the engines for vector changes during the launch and when the engine went out it appeared that they were still thrusting for full altitude since the engines were not throttled back for slowing or for the pitching maneuver to be performed until much later.

Engines for the final approach did not look as if they were throttled up at the end before turning them off on touch down either.

I do agree that it would have been better to be able to examine the ship for stress of launch through its profile but it seems that they need to go back to the engine fuel burn testing as they needed to change out one of the engines just after a fueling test firing...

GW Johnson · 2020-12-12 16:33:19

Well, remember: the Raptor is a new engine with a new propellant choice. It simply does NOT have the long experience base of the Merlin. Not yet.

GW

SpaceNut · 2020-12-12 20:26:11

Full video of Starship’s seven-minute high-altitude test flight

The test flight targeted an altitude of 41,000 feet, or 12.5 kilometers, higher than most commercial airliners fly.
One of the Raptor engines shut down a little more than a minute-and-a-half into the flight, followed by cutoff of a second engine more than three minutes after liftoff. The remaining engine switched off at about T+plus 4 minutes, 40 seconds, and the Starship’s thrusters and control flaps put the rocket in a horizontal “belly flop” orientation for the descent back to the ground.

Embedded video is one that gives a ground view of complete flight.

https://www.youtube.com/watch?v=STGWOEKhrtI
Video tape is 8 hrs long so skip towards the end....this one is the aborted run

Does not appear to be any legs on this unit along the sides so they must be under it

Another thing that is hard to tell is whether its on the leeward side of the ship designed to take the heat of re-entry...

SpaceX Starship nails ‘flip’ maneuver in explosive landing video Starship-SN8-launch-120920-Richard-Angle-10-crop-1024x504.jpg

For unknown reasons, that tank or its associated plumbing were unable to maintain the pressure needed to feed Raptor with enough propellant, resulting in fuel starvation mid-burn. A lack of fuel and surplus of oxygen effectively turned the landing engine into a giant oxygen torch, melting the copper walls of its combustion chamber (hence the green plume). Had the header tank maintained the correct pressure, SN8 would have very likely landed intact (or at least had a much softer landing).

That explains the issue with the engines

Oldfart1939 · 2020-12-13 00:23:04

Elon's move from California to Texas may be related to the personal income tax levied by California, versus that of Texas.

SpaceNut · 2020-12-13 22:21:38

BB1bOToV.img?h=600&w=799&m=6&q=60&o=f&l=f

https://youtu.be/ap-BkkrRg-o

this video is 1:50:00 minutes long so advance it to 1:47:00

The counter starts upward after ignition. Things that I note is a white band around mid way up from the tail that forms as it climbs just around 40 seconds the flame plume color shifts to a more yellow. Then as the engine start to move at only 1:35 into flight the engines start to twist before something that holds them together breaks just prior to the 1 engine going out. They split appart for a few seconds.

At 2:30 the plume changes again from the view of the outside and at 4:30 ish the single engine burps...before shutdown preparing for the glide. There were no legs visible in any of the frames for a landing to happen.

This is a wide angle view unaided
https://youtu.be/amFK58SSphY

Oldfart1939 · 2020-12-14 00:12:14

From all the footage I have seen, it seems that the problem of keeping a reliable fuel supply constantly available is paramount. The engine performance seemed a bit erratic as they began the sequential shutdown during the ascent. But all in all, it was a spectacular demonstration of new hardware in a big test. Kudos to the SpaceX engineering team!

Last edited by Oldfart1939 (2020-12-14 00:13:18)

Tmcom · 2020-12-14 03:22:46

Oldfart1939 wrote:

Elon's move from California to Texas may be related to the personal income tax levied by California, versus that of Texas.

Also the fact that the Mayor of California may make the vaccine mandatory, since he is an idiot, and Musk has publicly stated he won't be getting jabbed.

And he is closer to his megafactory, which may house the industrial complex for mass producing his rocket ships.

SpaceNut · 2020-12-22 18:12:19

post 860 showed sn9 leaning and not all that damaged but its now on its way upright and moving Starship SN9 rolling to launch site – Super Heavy construction ramps up

This multi-flow processing mandate at SpaceX Boca Chica allows for the goal of launching numerous prototype Starships to refine the flight profile, with SN9 still expected to fly to 12.5 km before a likely push to the original goal of between 15 and 20 km with a future Starship – pending the results of the SN9 flight.
A refined pre-launch flow will follow, likely requiring only a single cryo-proof testing run with Liquid Nitrogen, followed by a triple-Raptor Static Fire test.
Pending the results of those tests and the required clearance to proceed toward the launch, SN9 is expected to take to the air either side of the New Year, potentially before 2020 comes to an end.
Although Starship’s achievements in 2020 have been impressive, 2021 promises to be a banner year to develop the first fully and rapidly reusable interplanetary launch system.

other things to expect for changes

SpaceNut · 2020-12-24 16:49:49

Looks like its going to go for orbit....
The FAA released SpaceX's rough plan to fly Starship rockets to orbit from Texas, and the agency wants public input on it by January 22,

So far, SpaceX has launched a number of protoypes for Starship, a steel-skinned rocket ship that stands nearly 49 meters (160 feet) tall, from Boca Chica, a relatively remote strip of beachy land at the southeastern tip of the state.
But now SpaceX hopes to fly a larger, two-stage system called Starship-Super Heavy, which may stand 122 meters (400 feet) tall, weigh nearly 5 million kilograms (11 million pounds), and be capable of flying its upper-stage ship into low-Earth orbit.

BB1cc9Av.img?h=491&w=799&m=6&q=60&o=f&l=f

tahanson43206 · 2020-12-24 18:15:20

For SpaceNut re #874 ...

By any chance, did you catch the post in which a NewMars member (and contributor) reported living a few miles from the Texas SpaceX facility?

I would imagine the launch of the two stage vehicle would be both audible and visible from our member's vantage point, if I am recalling the post correctly.

(th)

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