SuperHeavy+Starship have the thermal energy of the Hiroshima bomb.

kbd512 · 2023-04-20 10:45:06

SpaceX is discovering what works and what doesn't by actually testing real rockets. Thus far, they have made progress much faster than SLS, which costs a half billion dollars per flight, only one can be constructed per year, and SLS has been under development for longer than the Saturn V program existed from start to finish (the time when nobody knew how to build an interplanetary rocket, including the engineers who actually built it). Saturn V had plenty of F-1 and J-2 engine ka-booms, but they were all on engine test stands.

There are two valid ways of approaching rocket engineering:
1. You can attempt to tweak everything about the engines and vehicle until you think it's perfect and give the false perception that everything worked perfectly from Day 1.
Or...
2. You can build and blow-up multiple low cost rockets. So long as you never repeat the same mistake twice, and make all of your mistakes before you start flying crews, SpaceX has proven this to be the fastest and lowest cost method for designing reliable launch vehicles.

NASA lost two Space Shuttles, probably thinking both times that their engineers had it all figured out. Well, they obviously didn't and spent obscene amounts of money proving that they didn't. Calling it a management decision when all the decision making happened inside Mission Control is very trite and very wrong.

We will never colonize Mars with STS and SLS. The goal behind those vehicles was to spend lots of money on giant rockets. Mission accomplished on that front. They utterly failed to produce anything capable of being used to colonize another planet. Each launch of SLS cost more than the entire development and hardware budget for all hardware built for and development work on Starship. After we launch dozens of Starships and lose a few of them during the testing process, we can move forward with a well-proven and reliable launch vehicle that also happens to be reusable and much cheaper than the only existing alternative.

I'm a little taken aback by this zero-defect mentality which seems to think there's always more money to be thrown into some aspect of something which someone thinks is an overriding consideration, more important than all others.

The part everyone thought would be hardest, getting the booster with 33 engines to complete a full burn duration, went about as well as it possibly could. Nothing exploded. The entire vehicle did a couple of backflips in the air and still held together until range control pulled the plug. The stage separation was clearly a stumbling block, but SpaceX will fix it the way they've fixed every other problem that's come up. How is the mere fact that they made it this far not proof-positive of that much? How many other companies have built and launched a rocket twice as powerful as a Saturn V, mostly on their own dime except for engine development money that the USAF gives to everyone, only to say to themselves, "That stage separation problem is just too hard to overcome. Let's give up now." The naysayers will do their best impression of horses, because that's what they do. Meanwhile, SpaceX has some problems to resolve before their next flight. Breaking some eggs is the first step to making an omelette. This first omelette was clearly over-done, but it still looked a lot like an omelette. The next one will be better. Every master chef requires lots of practice to become good at what they do.

Unlike the Soviets or Chinese or now our own government-backed space agency, who are all deathly afraid of failure and act as if it's the end of the world, the rest of us know that only failure actually teaches you something. SpaceX learned something today, no doubt, and can apply it to their next launch.

GW Johnson · 2023-04-20 11:16:11

I finally got to see some video of this event. It was clear early in the ascent that about half a dozen first stage engines were dark. Then as stage separation approached (per the announcer), I saw the start of some bright flashes at the base of the first stage, and as it began to spin I saw some plumes of fire going in unexpected lateral directions. There was very definitely something going wrong with getting a full-duration burn with 33 engines.

In addition I noticed something starting in the first flip around that probably few others noticed: the first and second stages were misaligned by a few degrees. Visually, this bend at the staging location was 5-10 degrees. Misalign parts that are supposed to separate, and they probably won't. They get jammed tight as things bend that are not supposed to bend.

A speculation only: thrust misalignments due to multiple lost engines let the vehicle get too much AOA on it during or near max q, bending the second stage out of alignment with the first, due to large air loads along the side of the vehicle (that aren't supposed to be there). That stopped the stage separation, causing the spin and the explosion. Maybe range safety blew it up, maybe it exploded spontaneously (rockets spinning sideways often did explode spontaneously in the 1960's).

Something you all ought to understand: spinning the rocket end-for-end to separate the stages is pure ignorant bullshit. The vehicle needs to stay utterly straight to the wind stream (significant since they were only just past 100,000 feet at around Mach 2 going up). You separate, applying positive thrust with some sort of thruster to the second stage, and ideally some sort of negative thrust on the first stage. Once they separate, then you light the main engines on the second stage, and with a reusable first stage, that separation distance at second stage ignition needs to be a vehicle length or more. Otherwise your second stage rocket plumes burn holes in the first stage you wish to recover.

The positive second stage low thrust during separation provides both separation distance and propellant ullage acceleration for lighting the second stage main engines. You need it because of ignition ullage requirements in free fall, and to prevent the first stage from getting sucked back into a collision with the second stage by the drag "shadow" of its wake. In racing, that effect is called "drafting".

If you add a little deceleration thrust with attitude thrusters on the first stage, you increase the probability of a successful separation (avoiding "drafting") while in supersonic airflow, and you increase the separation distance between them more rapidly. The first stage then flips around to do its burn-back burn, AFTER separation is complete and the second stage has ignited and moved safely away.

SpaceX knows all this; learning this the hard way with Falcon-1 at their outset, almost bankrupted them. They did not have these problems with Falcon-9 and so far with Falcon-Heavy. To see this happening again with Starship/Superheavy suggests "something else" went wrong to cause it.

My speculation is that too many engine-outs (and possible explosions or bell ruptures ) induced side forces that caused vehicle AOA too large relative to the slipstream, in turn causing causing the vehicle to bend and jam at the stage separation zone, before staging ever began. If I was SpaceX, I would look there first.

GWJ

Last edited by GW Johnson (2023-04-20 11:20:52)

Void · 2023-04-20 12:33:31

I recall the landing of Falcon 9 1st stage, the effort to get it done. Many failures. I recall that many people got frustrated, but they got there big time in the end. We just don't seem to see them crash anymore.

Internal Server Error again!

Patience and learning are needed. I consider everything to be big luck here. More engine failures in an asymmetrical pattern and the thing might have failed on the pad in some manner. Probably blowing up the pad I might guess.

I note the truth of what you provide for knowledge Dr. Johnson, but I am rather in the same thinking of kdb512.

Lots of patience needed. Lots of teething ahead. Lots of Elon Time I would imagine.

But in Elon Time things eventually get done.

Last edited by Void (2023-04-20 12:39:43)

Void · 2023-04-20 12:41:45

Done

RobertDyck · 2023-04-20 12:45:42

At 16 seconds after lift-off, showing 3 engines not burning.

At 1 minute and 17 seconds after lift-off, showing a high-resolution telescope image of the rocket confirming 5 engines not burning. (or is it 6) Note telescope image is reversed left-right from diagram. (Or is it rotated?)

At 1 minute and 42 seconds after lift-off, showing 6 engines not burning.

At 3 minutes and 59 seconds after lift-off. It shows the 6th engine to fail had re-lit. However, this shows range safety had activated self-destruct. "It blow'd up real good!"

Void · 2023-04-20 19:14:31

I saw an article that indicated Hydraulic failures as well for the steering, perhaps.

Not sure they are going to keep hydraulics, but go electric?

But perhaps it was a cascade problem where an asymetical engine failure pushed the steering too far?

Then that damaged the 2nd stage separation?

But of course I don't know. Maybe they were all parallel problems.

Done.

Last edited by Void (2023-04-20 19:16:13)

SpaceNut · 2023-04-20 19:20:46

The end over end tumble was strange to see as it appeared that the coupling between the staged did bend a bit. It was sort of sad to see the number of engines that failed as well and how soon after liftoff that it happened. Even in engine tests we did see the engine or engines going out.
Since there is only a black box one can only hole that there is data to help in getting the rocket fixed.

Void · 2023-04-20 19:37:11

Stage '0' was apparently really ripped up, so I am guessing they will want to address that somehow. (That is the launch pad).

I can't find a picture of it but I saw one that looked like it dug a deep hole, and messed up the launch mount.

https://news.yahoo.com/powerful-blast-s … 00340.html
Picture Quote: 7da145b88746b0eac387b545ebc1f788

So.......OOPS!

Done.

Last edited by Void (2023-04-20 19:45:13)

RobertDyck · 2023-04-21 03:58:33

YouTube: Analysis SpaceX's Stage Zero HUGE DAMAGED "33 engines DESTROYED the pad"...
Launch pad damaged. There was concrete beneath the launch pad before launch. There's a crater there now. May I please suggest a thrust diverter, just like launch complex 34, used for Saturn 1 and Saturn 1B rockets?

I visited KFC in year 2000. I took the "Then and Now" tour. This included a mini-bus that took us to the launch pad for Mercury, the block house for Gemini, and launch complex 34 for Saturn 1 and Saturn 1B. We were able to walk under the launch pad and read the memorial plaque. What I read says you're not allowed to do that now.

tahanson43206 · 2023-04-21 06:10:27

For RobertDyck re #34

Thanks for this update, and for your recollections of visiting KFC in 2000!

An over-water launch (such as from the oil platforms considered briefly) would offer a natural "thrust diverter".

However, the launch pad would need to be designed to permit flow of hot gases through the deck to the natural energy absorber below.

I note that animations of Starship launches need to be adjusted to account for the excavation of concrete from the launch tower.

(th)

Calliban · 2023-04-21 08:21:28

Concrete would have been vulnerable to cracking, due to the enormous temperature gradient introduced by the rocket backwash. The fractured surface would have had very little shear strength against the dynamic pressure of the exhaust. A thrust diverter would have solved the problem. Steel plate connected to sunken bolts might have worked. But given the existence of a 50 year old engineered solution (the diverter), why did SpaceX not use it?

tahanson43206 · 2023-04-21 10:06:42

For Calliban re #36

This is just a guess on my part, but I suspect that the offshore launch platform was the preferred location for permanent facilities, and the Boca Chica site was such a hassle it may have been seen as a short term solution.

Perhaps in future recollections of the early years of Starship, we may be given insight into decisions made by the engineers (and management) of the time.

Here's another guess .... Elon may have chosen to keep the "olden days" approaches off premises, due to the risk of contamination of modern engineering.

The "olden days" folks are still alive and receiving ample salary, in other companies.

(th)

RGClark · 2023-04-21 12:27:03

GW Johnson wrote:

…
Something you all ought to understand: spinning the rocket end-for-end to separate the stages is pure ignorant bullshit. The vehicle needs to stay utterly straight to the wind stream (significant since they were only just past 100,000 feet at around Mach 2 going up). You separate, applying positive thrust with some sort of thruster to the second stage, and ideally some sort of negative thrust on the first stage. Once they separate, then you light the main engines on the second stage, and with a reusable first stage, that separation distance at second stage ignition needs to be a vehicle length or more. Otherwise your second stage rocket plumes burn holes in the first stage you wish to recover.
…
GWJ

What they’re discussing at SpaceX right now, “Ok, whose bright idea was it not to have a stage separation mechanism?”

This article discusses the decision not to have a stage separation mechanism:

https://www.teslarati.com/spacex-starsh … -extremes/

An unfortunate decision because if the stages did separate there might not have been any need to send the destruct signal. Plus, you would have gotten far more data by seeing what the Starship upper stage could do.

Bob Clark

RGClark · 2023-04-21 12:36:29

RobertDyck wrote:

YouTube: Analysis SpaceX's Stage Zero HUGE DAMAGED "33 engines DESTROYED the pad"...
Launch pad damaged. There was concrete beneath the launch pad before launch. There's a crater there now. May I please suggest a thrust diverter, just like launch complex 34, used for Saturn 1 and Saturn 1B rockets?
https://upload.wikimedia.org/wikipedia/ … ectors.jpg
I visited KFC in year 2000. I took the "Then and Now" tour. This included a mini-bus that took us to the launch pad for Mercury, the block house for Gemini, and launch complex 34 for Saturn 1 and Saturn 1B. We were able to walk under the launch pad and read the memorial plaque. What I read says you're not allowed to do that now.
…

Reading discussions on various forums online, there is universal agreement that not having a flame diverter was a mistake. With the amount of concrete thrown up it was lucky there was not catastrophic damage to the rocket. Damage beneath the launch pad was extensive:

FuPvv2mXgAIJgui?format=jpg&name=900x900

Bob Clark

Last edited by RGClark (2023-04-21 12:37:01)

GW Johnson · 2023-04-21 16:13:49

I actually suspect that there was "catastrophic damage" done to some of the first stage engines by debris kicked up from launch pad damage, which was considerable. Did no one else see the odd fire plumes coming out at angles up to almost 90 degrees while the thing was spinning? And the little flashes of fire that suggested small explosions? I saw them. Those suggest damaged or partly-missing engine bells.

At short range, the blast force of a rocket exhaust is numerically equal to its thrust. The area it is imposed upon is about the same as the base area of the rocket vehicle. For 17 million lb of thrust on a circle 30 feet in diameter, that's just about 24,000 psf = ~170 psi blast pressure. Now double or triple that for the transients of ignition, and double or triple it again for uneven distribution effects. ~1500 psi.
Considering thermal shock effects too, that's way beyond what any concrete can take as a rapid transient.

Some of those chunks of shattered concrete were flung outward as debris, you can see that in the videos. Which means some of it was flung upward, and some of that must have hit those engines. It is inevitable. Cracked and leaking bells are going to wash adjacent engines with leaked hot gas plumes. That will play merry hell with wiring and with plumbing.

So the rocket went out of control, bent itself to where staging was jammed, and then fell spinning out of control. Surprise! Surprise!

GW

Last edited by GW Johnson (2023-04-21 16:17:25)

Calliban · 2023-04-22 03:23:25

Something I neglected to mention earlier. When reinforced concrete is exposed to fire, it can undergo explosive spalling. When this occurs, scabs of concrete are blasted away from the surface at high velocity. This occurs because concrete is a hydrated material, with relatively poor thermal conductivity. Two processes occur during fire that tend to result in explosive spalling. Firstly, extreme temperature gradients in the concrete lead to shearing stresses parralel to the surface, due to differences in thermal expansion vs depth. This leads to cracking, most typically at the interface with reinforcing rods. Secondly, as the concrete heat up, pore pressure increases due to steam generation. Steam bubbles form in pores between the concrete and reinforcing rods. As cracks grow and pore pressure builds, the surface can fail catastrophically, shooting off scabs of concrete and exposing the reinforcing rods. Rocket exhaust is a lot hotter than a typical building fire, and the concrete is being blasted with hot gas under forced convection. So heat transfer rates will be much higher. So spalling would have been a certainty for any exposed concrete structure.

Spalling would have produced concrete scabs several inches in diameter, fired away from the surfaces at several tens of metres per second. When combined with the the momentum imparted by the rocket backwash, this debris could certainly have damaged the regenerative cooling channels in the engine bells. This is quite an amateur mistake for a company as big and as technically qualified as SpaceX. Civil engineers must have been involved in the design of the launch pad. Spalling is a well understood phenomena. They should have seen it coming. It is embarassing that they didn't. I can only imagine that they were so focused on the design of the rocket, that they neglected the design of the pad.

As an aside, this accident has implications for landing on the surface of Mars. The surface there will be covered in loose debris and there may be ice pockets beneath the surface that explode when subjected to engine heat. Its behaviour under the sort of blast that it will encounter due to rocket exhaust is unknown, but is likely to be similar to what occured during the test flight at Texas. Without a properly engineered pad, the damage to the engines may prevent any subsequent takeoff. This is a problem that needs to be solved before any manned expedition is attempted. Previously, my thinking had focused on fibre reinforced compressed regolith, with a base of heavy stones. But now I wonder if a steel cap is needed.

Last edited by Calliban (2023-04-22 03:37:51)

SpaceNut · 2023-04-22 08:24:36

Seems like they should have just copied what worked for the staging separation since the only means to achieve booster separation for escape for crew safety is for the starship to have that ability as early as it can.
We know that Starship even by itself cannot achieve orbit unless it gets close to the altitude required so anything lower means a sub orbital flight and landing that it has shown that it is capable of.

tahanson43206 · 2023-04-22 09:23:33

For SpaceNut re #42

Your suggestion in this post deserves it's own topic.

When the time comes for passenger certification of Starship, I would expect that the company itself, let alone regulators and insurance companies, will expect to see a reliable escape system for Starship.

Here is something for us all to ponder as we wait for SpaceX to implement a reliable Starship escape system .... How would the Starship control software have known when to escape, in the flight we just witnessed?

If the First Stage is still thrusting, as was definitely the case here, my question is whether Starship could have pulled away from the First Stage even if it wanted to?

(th)

tahanson43206 · 2023-04-22 09:35:16

It should surprise no one that Starship is grounded until further notice...

SpaceX reveals why Starship exploded minutes into launch
615
Julia Musto
Fri, April 21, 2023, 11:26 AM EDT

Following the flight, the Federal Aviation Administration (FAA) has grounded the vehicle.
The agency said it would oversee the mishap investigation of the test mission, noting that "an anomaly occurred during the ascent and prior to stage separation resulting in a loss of the vehicle."

(th)

RGClark · 2023-04-22 10:26:21

I wanted a separate static test stand for all 33 engine engines constructed because I had no confidence all 33 Raptors would burn for the full flight duration. The idea of damage to the pad from the demolished concrete from the thrust was not even on my radar.

But if the full test stand had been constructed, this is another major flaw that would have been picked up beforehand.

Bob Clark

RobertDyck · 2023-04-22 11:36:04

The launch pad could be used as a test stand. Depending on strength of the hold-downs of the launch pad, and strength of the foundation anchoring the launch pad to the ground. SpaceX does static fire tests prior to launch. They need ability to conduct a full-duration test burn.

RobertDyck · 2023-04-22 11:49:46

Escape system: I wouldn't have designed crew vehicle the way Starship is designed. I would design with a detachable capsule that uses a parachute to land, like New Shepard or Falcon 9 / Dragon. Or a winged orbiter like Shuttle, or lifting body like HL-20 / DreamChaser. All these allow landing without power. A propulsive landing requires high precision. But propulsive landing is the only option on the Moon or Mars. So, Starship is really designed for the Moon or Mars. A radical re-design is not an option, so the only valid alternative is what SpaceNut suggested. Ability for Starship to separate from the SuperHeavy booster at any point in flight. Use Starship as the escape pod. Commercial aircraft do not have parachutes or other escape system; the aircraft either lands or all passengers and crew lose their lives. Starship is designed with this principle. The F-111 Aardvark aircraft was designed with a detachable cockpit pod. Rather than ejection seats and parachutes, the whole pod separates and parachutes down. The reason was to allow escape during supersonic flight. You could think of Starship as the escape pod. Again, conclusion is Starship must be able to separate at any point in flight.

20:20 hindsight. But this is why SpaceX tests early and often. To learn lessons like this.

Steve Stewart · 2023-04-23 06:15:48

Here's some of the latest news on Starship. (Sunday AM 4.23.2023)

Here's what caused the SpaceX Starship explosion and how it's different for Florida

The article states:
"SpaceX did later confirm the rocket's breakup was triggered by FTS."
(Flight Termination System)

Elon Musk Sends Important Message About SpaceX

Calliban · 2023-04-23 14:42:39

A lesson from history: The largely forgotten story of airship R101. Britain's attempt at trans-continental air travel before aeroplanes had sufficient range and reliability to do the job. The Graf Zeppellin had completed the first round-the-world flight in 1928 and routinely carried passengers from Germany to Brazil. Such a long journey was far beyond the capability of any aeroplane of that time. A British airship had completed the first east-west trans-Atlantic flight a few years earlier. It seemed to many that the age of regular transcontinental air travel had arrived.
https://m.youtube.com/watch?v=ZxlV_GGU5YQ

Like Starship, R101 was a new vehicle testing new technological innovations. Corners were cut to meet a political schedule and the ship was flown in spite of known design problems. Technologies were not sufficiently well developed. The diesel engine was an immature technology in 1930, with petrol being far more commonly used. High strength alloy steels were used in the airframe. These had fewer fatigue issues than aluminium alloys, but they made the airframe heavier. Probably the worst design flaw of all was the use of cotton for gas cell envelopes and the outer cover. This lost strength when wet and rotted. This was the direct cause of the accident that killed all but 6 of the men onboard. A gust of wind tore the outer cover and deflated the forward gas cells, causing a loss of lift. As the airship settled on the ground, the weight of the airframe pushed one of the diesel engines into the hull, igniting hydrogen that had leaked out of the damaged gas cells. The accident ended Britain's imperial airship programme. Let us hope that Starship does better than R101.

Last edited by Calliban (2023-04-23 14:53:57)

RGClark · 2023-04-23 18:07:14

Looks like 8 engines out in this frame based on the fact the outer ring should have 20 engines firing, so it’s missing 6, and the inner ring should have 3 engines firing so it’s missing 2, though one of the inner ring engines may be partially firing:

Bob Clark

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#26 2023-04-20 10:45:06

Re: SuperHeavy+Starship have the thermal energy of the Hiroshima bomb.

#27 2023-04-20 11:16:11

Re: SuperHeavy+Starship have the thermal energy of the Hiroshima bomb.

#28 2023-04-20 12:33:31

Re: SuperHeavy+Starship have the thermal energy of the Hiroshima bomb.

#29 2023-04-20 12:41:45

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#30 2023-04-20 12:45:42

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#31 2023-04-20 19:14:31

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#32 2023-04-20 19:20:46

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#33 2023-04-20 19:37:11

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#34 2023-04-21 03:58:33

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#35 2023-04-21 06:10:27

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#36 2023-04-21 08:21:28

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#37 2023-04-21 10:06:42

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#38 2023-04-21 12:27:03

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#39 2023-04-21 12:36:29

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#40 2023-04-21 16:13:49

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#41 2023-04-22 03:23:25

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#42 2023-04-22 08:24:36

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#43 2023-04-22 09:23:33

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#44 2023-04-22 09:35:16

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#45 2023-04-22 10:26:21

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#46 2023-04-22 11:36:04

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#47 2023-04-22 11:49:46

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#48 2023-04-23 06:15:48

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#49 2023-04-23 14:42:39

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#50 2023-04-23 18:07:14

Re: SuperHeavy+Starship have the thermal energy of the Hiroshima bomb.

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