GDB wrote:

On a more positive and relevant note, SpaceX has done a test of a reworked FTS, at Boca China.
As for the second site at KSC, well that’s NASA territory so the Starship complex under construction there will have to comply with what they deem acceptable, as it is an an early stage this should be easier.

That’s a huge positive, and I think them trying to launch out of NASA/USAF turf will be an added benefit to the program.

Regardless of test launch result, having a skyscraper size flying bomb out of control without a reliable way to self destruct it is about one of the worst results you can get.

mxaxai wrote:

Avatar2go wrote:

None of this alters the fact that Shuttle was a step in the progression of increasing access and decreasing cost. Nor does it lend any significance to the comparison of Shuttle to Falcon, programs separated by 30 years and vastly different designs and goals.

Of course.

What's the 'Of Course'?

That F9 came after the shuttle. Yep.

That the Shuttle was "a step in the progression of increasing access and decreasing costs". That's not obvious. The current low-cost, high access launchers do not seem to use any obvious Shuttle technology, and the SLS is not clearly increasing access or decreasing costs.

If someone in a non-condecending tone wants to explain how the Shuttle helped improve current technology, I'm interested. Especially if they can explain how that improvement was worth any significant fraction of the $200B spent.

(The SLS might some day increase manned_access_past_LEO, but it will have to launch people there first. It's been 13 year, so they must be getting close!)

Avatar2go wrote:

flyingturtle wrote:

(some stuff)

I can only presume you didn't read, or didn't understand, any of my statements. And therefore are repeating your own beliefs in complete oblivion to the facts I presented, which you have not refuted nor offered any evidence to the contrary.

Therefore I will consider this a matter of your belief and opinion, to which you are entitled, and which is unresponsive to facts and evidence.

Avatar2go ...

Lots of what you write is super informative. I just read your posts on the T-7A and liked them. Posts like that are good. But as someone who often enjoys reading what you write .. maybe less of this please. (Tone can be hard on the internet .. I'm trying to be super polite here.)

kitplane01 wrote:

That the Shuttle was "a step in the progression of increasing access and decreasing costs". That's not obvious. The current low-cost, high access launchers do not seem to use any obvious Shuttle technology, and the SLS is not clearly increasing access or decreasing costs.

I agree 100%

Quotes from the SLS budget section.

However, at the rate that it flew, the final cost was $1.64 billion per Space Shuttle launch

Ultimately, Europa Clipper was rebooked to launch on a Falcon Heavy for a contract price of $178 million

https://en.m.wikipedia.org/wiki/Space_L ... nd_Artemis

Besides developing some cool heat tiles the Space shuttle was definitely a failure. It did not lower the cost to space. It did not improve access to space. It was more expensive per kg than previous launch system.

Falcon heavy can put more payload into orbit than the space shuttle. Falcon 9 using crew dragon can put astronauts into space like the space shuttle. You could launch two flights for a fraction of a single space shuttle launch. The launch cost is probably less than 10% per kg or per astronaut.

In terms of Artemis it is not a step forward. Boeing has a contract for 8 upper stages at $800 million each for example. Cost per kg into Lunar orbit would be 10 times maybe even 20 times the cost of Falcon Heavy.

Of course the Orion capsule is too heavy to fit on a Falcon Heavy but that is besides the point. A system could be developed for any sized heavy launch vehicle. NASA putting the Falcon Heavy design and scaling it up to the size they wanted would be far superior to anything they have come up with.

Please be sure to discuss the topic. Off topic comments will be removed.

✈️ atcsundevil

Tim Dodd, a.k.a. Everyday Astronaut, discussing something much brought up, not least in the general media at times, the comparison between the Soviet N-1 and the Superheavy/Starship, are the large number of engines a fatal flaw?
https://www.youtube.com/watch?v=AgqZMK22LEk&t=20s

He acknowledges his skin in the game, from access Musk gave him and his selection on Dear Moon, nonetheless a detailed look at both rockets and is there really any comparison?

No comparison. There is a reason why only 4 engined passenger airliners were allowed to fly long distance over water for many decades.

At the opposite extreme take a 3 engine starship. If one engine fails 5 seconds after launch the entire pad gets destroyed. The rocket cant climb at 66% power. Once you get to around 9 engines suddenly the mission can still be completed with a single engine out.

So operating less than 9 rocket engines would be like a single engine passenger airliner. No redundancy. 9-18 engines would be like a twin engine passenger airliner. 18-27 rockets would be like a trijet. 27+ is like a safe four engines passenger plane.

I'd say 20 engines is the minimum number of engines needed for a system that can reach airline safety levels. So 33 isn't such a crazy number.

If for instance SpaceX made a raptor with 3 times the power to allow for only 9 engines on the lower stage that same engine could not be used on the upper stage. The upper stage while landing, the single big engine would not be able to throttle down low enough to hover. This is what determined the size of raptor in the first place. The upper stage empty is only around 100t. A single raptor 2 has 230t of thrust. So the engine has to throttle down to around 50% to get into a hover.

https://en.m.wikipedia.org/wiki/SpaceX_Raptor

SpaceX wanted to concentrate on one engine and mass producing it to get economies of scale. Maybe once they are making multiple engines per day and they have dozens of operational starships they might consider making Super Raptor engines for the lower stage only.

GDB wrote:

Tim Dodd, a.k.a. Everyday Astronaut, discussing something much brought up, not least in the general media at times, the comparison between the Soviet N-1 and the Superheavy/Starship, are the large number of engines a fatal flaw?
https://www.youtube.com/watch?v=AgqZMK22LEk&t=20s

He acknowledges his skin in the game, from access Musk gave him and his selection on Dear Moon, nonetheless a detailed look at both rockets and is there really any comparison?

No real comparison. A separation of 40 years in technology and design. N1 struggled from an inability to simultaneously and stably control that many engines. It's very possible with computer control today, to solve that problem.

The only significant similarity, is the force and energy developed by that many engines, which remains a challenge for launch facilities, as we saw in the Starship launch.

Avatar2go wrote:

GDB wrote:

Tim Dodd, a.k.a. Everyday Astronaut, discussing something much brought up, not least in the general media at times, the comparison between the Soviet N-1 and the Superheavy/Starship, are the large number of engines a fatal flaw?
https://www.youtube.com/watch?v=AgqZMK22LEk&t=20s

He acknowledges his skin in the game, from access Musk gave him and his selection on Dear Moon, nonetheless a detailed look at both rockets and is there really any comparison?

No real comparison. A separation of 40 years in technology and design. N1 struggled from an inability to simultaneously and stably control that many engines. It's very possible with computer control today, to solve that problem.

The only significant similarity, is the force and energy developed by that many engines, which remains a challenge for launch facilities, as we saw in the Starship launch.

Which he explained.
If you really want a deep look on the N-1, it’s part in the Moon race, how the internal and external politics, affected it and the whole of the Soviet space effort, from funding to hostility from the military, the constant changing of plans and priorities, I highly recommend ‘The Soviet Moon Race With Apollo’ by Asim A Siddiqi, it was published in 2000 which though a long time ago, there was much greater access in the years writing it and many of the protagonists were still alive or had left extensive diaries.
So this video isn’t for me, just an answer to a oft quoted comparison.

According to Jim Free at the AESB meeting, NASA has met with the FAA to emphasize the importance of launch cadence to the Artemis program, and the large number of Starship launches that lay ahead, to meet the Artemis milestones. FAA is still in the midst of the mishap investigation with SpaceX.

Free said they are on the same page. FAA has said they will do all they can to commit resources and process the next launch permit in a timely fashion. NASA is also looking beyond that to a multiple launch permit.

Free’s concern is when Starship HLS will be ready. The first orbital launch attempt of Starship failed in April, severely damaging the launch pad in the process and creating a massive cloud of debris that covered not only a nearby town, but protected wildlife refuges. Environmentalists are suing the FAA for inadequate environmental reviews before approving the launch. The FAA regulates the commercial space launch industry and U.S. commercial space launches require an FAA license.

Free said NASA has been talking to the FAA and “I think we’re in sync now,” but they are looking at just the next launch license, not NASA’s big picture of everything that has to happen before Starship HLS is ready for Artemis III.

https://spacepolicyonline.com/news/star ... t-artemis/

Avatar2go wrote:

No real comparison. A separation of 40 years in technology and design. N1 struggled from an inability to simultaneously and stably control that many engines. It's very possible with computer control today, to solve that problem.

I think there is a real comparison. The multiple rocket engines design was the Achilles heel of the N1 and is the Achilles heel of Starship.

A 33 engines rocket has a very complex fuel system to feed that many engines from one fuel tank and one oxidizer tank. And all these many engines have to work together in very close proximity, fixed to a structure, which is built as light as possible.

This causes lots of vibrations and interferences between the engines. Modern computer control helps but doesn't solve all these fundamental problems.

And simply from a statistical point of view, a 33 engine rocket has a 6.6 times higher probablity of an engine failure than a rocket with five rocket engines only. And the 33 engines design is not fail safe. Given the close proximity of the 33 engines, one single exploded rocket engine can ruin your whole day.

On Starship's last flight, the failure of six engines (18%) caused the end of the mission. That is like a four engined aircraft, which can't fly anymore, if one engine fails.

Wernher von Braun did very well, when he used just five rocket engines on the Saturn V.

Heinkel wrote:

I think there is a real comparison. The multiple rocket engines design was the Achilles heel of the N1 and is the Achilles heel of Starship.

A 33 engines rocket has a very complex fuel system to feed that many engines from one fuel tank and one oxidizer tank. And all these many engines have to work together in very close proximity, fixed to a structure, which is built as light as possible.

This causes lots of vibrations and interferences between the engines. Modern computer control helps but doesn't solve all these fundamental problems.

And simply from a statistical point of view, a 33 engine rocket has a 6.6 times higher probablity of an engine failure than a rocket with five rocket engines only. And the 33 engines design is not fail safe. Given the close proximity of the 33 engines, one single exploded rocket engine can ruin your whole day.

On Starship's last flight, the failure of six engines (18%) caused the end of the mission. That is like a four engined aircraft, which can't fly anymore, if one engine fails.

Wernher von Braun did very well, when he used just five rocket engines on the Saturn V.

Agreed that all the N1 challenges remain. I was just pointing out that there is a much better toolbox available today to deal with them. The IFT was not a great test of those systems. So I guess we will see what happens in the next launch.

Along those lines, Elon has tweeted that there will be another 6 to 8 weeks until the pad is ready. Which puts us at around 4 months. I would not be surprised if there is another similar extension in August.

This discussion does make me steal the term from planes and wonder how often failures are "uncontained." I'm not a rocket scientist

ssteve wrote:

This discussion does make me steal the term from planes and wonder how often failures are "uncontained." I'm not a rocket scientist

Do we know if Starship had an uncontained engine failure? I haven't paid much attention of late.

zanl188 wrote:

ssteve wrote:

This discussion does make me steal the term from planes and wonder how often failures are "uncontained." I'm not a rocket scientist

Do we know if Starship had an unconfined engine failure? I haven't paid much attention of late.

I don't think we know anything as of yet, besides what Elon said in the Twitter Spaces meeting. All he really said was that there was not evidence that the Raptors failed due to flying debris from the launch.

zanl188 wrote:

ssteve wrote:

This discussion does make me steal the term from planes and wonder how often failures are "uncontained." I'm not a rocket scientist

Do we know if Starship had an uncontained engine failure? I haven't paid much attention of late.

Well, visible in the lauch video it's clear that 2 adjacent engines on the outer rim failed/shut down early in the climb. The adjacent position of these two can't be coindicental?
I guess it's possible a failure in a common fuel/oxidizer supply caused the outages - I'm not sure how the engines fed.

People badmouthing the N1 need to look a little closer. The 4th try came very close to succeeding and the next probably would have worked if the program hadn't been cacelled.

Nomadd wrote:

People badmouthing the N1 need to look a little closer. The 4th try came very close to succeeding and the next probably would have worked if the program hadn't been cacelled.

Yes, the N-1F was vastly improved.

Nomadd wrote:

People badmouthing the N1 need to look a little closer. The 4th try came very close to succeeding and the next probably would have worked if the program hadn't been cacelled.

That was discussed in the book I mentioned upthread, it cannot be stressed enough how the death of the Chief Designer in 1966, long and bitter personal rivalries and their design offices, great financial restraints, military interference and pressure and technological weaknesses including in the area of engine controls, undermined the N1 and the whole Soviet program.

A memorable three part series the BBC did in 1991, ‘Red Star In Orbit’, interviewed some of those involved, including a Cosmonaut who gave his own assessment on why he and others never made it to the Moon, he cited the US creating a very good central organization, NASA, in contrast to the supposedly centrally planned USSR, where there were multiple plans, for different rockets, programs, objectives from those other designers, who acted as Soviet propaganda would have said the NASA contractors would do.

Imagine if during Apollo other contractors and political interest carried on pushing and sometimes got some funding, for to give an example, the Nova Superbooster, different Command and Landing systems etc?

GDB wrote:

A memorable three part series the BBC did in 1991, ‘Red Star In Orbit’, interviewed some of those involved, including a Cosmonaut who gave his own assessment on why he and others never made it to the Moon, he cited the US creating a very good central organization, NASA, in contrast to the supposedly centrally planned USSR, where there were multiple plans, for different rockets, programs, objectives from those other designers, who acted as Soviet propaganda would have said the NASA contractors would do.

Imagine if during Apollo other contractors and political interest carried on pushing and sometimes got some funding, for to give an example, the Nova Superbooster, different Command and Landing systems etc?

This is a very good point. NASA has focused the nation's public and private resources on specific national goals, that are generally pursued until they are acheived.

And for all the complaining about NASA, they have successfully managed those programs over time. Certainly not perfectly and without issues arising, or lessons learned. But even those issues & lessons are public, and debated in the public domain, not hidden to appear later in program collapse, as occurred in the Soviet Union.

Avatar2go wrote:

And for all the complaining about NASA, they have successfully managed those programs over time. Certainly not perfectly and without issues arising, or lessons learned. But even those issues & lessons are public, and debated in the public domain, not hidden to appear later in program collapse, as occurred in the Soviet Union.

As I recall Eisenhower did that intentionally and it’s built into NASAs charter.

SpaceX is aiming very high because of Musk. It’s amazing and a bit distressing to imagine where the space industry would be without him.

FAA and SpaceX have filed their motions in the environmental lawsuit, right at the deadline.

Both declined to defend on the basis that the suit is meritless, and asked for summary dismissal.

At least SpaceX did admit that the IFT launch pad was damaged and the launch was a failure. They characterized it as "scattering dust and debris".

FAA response:
https://storage.courtlistener.com/recap ... 3.18.0.pdf

SpaceX response:
https://storage.courtlistener.com/recap ... 3.17.0.pdf

Avatar2go wrote:

At least SpaceX did admit that the IFT launch pad was damaged and the launch was a failure. They characterized it as "scattering dust and debris".

Can you please quote where they said the launch was a failure?

Avatar2go wrote:

There is unconfirmed reporting that SpaceX had ranked destruction of the pad as an unlikely event, in their launch application.

SpaceX was correct. The pad was not destroyed. The pad was only damaged.

Damage - to harm or spoil something

Destroy - to damage something so badly that it cannot be used

https://dictionary.cambridge.org/dictio ... ish/damage
https://dictionary.cambridge.org/dictio ... sh/destroy

Please keep your emotions in control and use appropriate wording.

It's kind of like Apollo 13. The response to the screwup, fixing the pad in less time than the hired anti Musk heads thought was possible, the ship holding together while cartwheeling and FTS charges going off, (not exactly desirable, but impressive) newer, better engines already waiting, clearing the pad and almost making it to staging after everything that went wrong...showed a lot of the best of the company.
The insistance of the person who's been flooding the forum with his posts that they're doing everything wrong when they're achieving more in less time with far less money than his favorite oldspace companies could dream of is plain absurd and not fooling anyone who doesn't want to be fooled.

The launch pad beneath the stool was destroyed during IFT, with large chunks of it being thrown large distances at high velocity, causing damage to the surrounding area and infrastructure, and a large crater being excavated that exposed the foundations of the launch stool. This is undisputed, except for some reason, in this thread.

The launch stool and the tower were only damaged, not destroyed. We don't know the extent of the damage, as SpaceX has released no information. Some damage is to be expected, as ocurred also for the Artemis launch. For Artemis, NASA has detailed the tower repairs, and the pad 39b flame diverter sacrificial coatings and parts always need to be replaced.

Currently we are over 2 months out from IFT, with at least another 2 months to go until the next launch, according to Elon. I mentioned earlier in the thread that it would be 4 to 6 months before the facility would be ready to launch again. My expectations are still around 6 months, but we shall see.

With regard to the launch being a failure, as noted this is the subject of Wikipedia wars, and apparently here as well. It depends on where you set the benchmark for success.

I set the benchmark for the long-stated goal of achieving the SpaceX-prescribed orbital flight plan. Elon continues to also assess success in these terms, stating recently he expects a 60% chance of successfully reaching orbit in the next flight.

Others set the benchmark at the more recently lowered goals of clearing the launch tower and leaving the launch facilities in a state of reuse. In those terms, I would say IFT was a partial success.

IFT did clear the tower, but in only a partially controlled manner, with engines failing steadily during the launch and the climb. It had an uncommanded tilt and lateral translation, and continued to lose thrust control during the climb, causing a tumble and FTS destruction. The FTS also did not work as designed, leading to an extended tumble and large debris.

The pad needs to be entirely rebuilt, but the stool and tower survived, and are being repaired. The solution of the steel plate with high pressure water spray should prevent the destruction of the pad in the next launch. How well it will work in other regards, remains to be seen.

The FTS has been redesigned and undergone ground testing with water-filled tanks. Hopefully it will function correctly if needed in future launches.

The two stage vehicle held together during the tumble, which some have pointed to as being significant to the spin separation strategy. However SpaceX has now abandoned that strategy in favor of hot staging, for future launches.

In my view, any flight that requires FTS is a failure by definition. I'm not aware of any other destructed launch vehicle that was considered a success. But we are unlikely to resolve that question here, so will have to agree to disagree.

Was the launch a failure? Yes, of course it was in that the goals were not achieved. However, we can also be equally certain that valuable information was gleaned and much learned by this failure. Failure is part of the learning process. Too many fall for the slick tongues and bright eyes of billionaires.

Another potential issue is the upcoming August expiration of the Congressional prohibition on FAA rulemaking for commercial spaceflight. Currently the FAA can only consider the safety and risks associated with people on the ground. Commercial passengers need only be advised of the risks by the providers.

FAA has signaled their readiness to begin formal rulemaking. They already have formulated recommended best practices, which are more or less observed by the industry. Those would become codified, and FAA would form a spacecraft advisory rulemaking council, similar to the existing aircraft advisory council.

The industry is still lobbying Congress to extend the prohibition, saying the technology is not yet mature. It has already been extended twice. Right now, only SpaceX, Blue Origin, and Virgin Galactic have commercial passengers. NASA commercial crew is excluded, as is ISS, since NASA has its own safety panel and apparatus.

However as the transition occurs to private space stations, the orbital commercial space passenger transport capacity is expected to grow. SpaceX, Blue, and Boeing are expected to offer services initially. SpaceX has plans to include Starship in that offering.

Avatar2go wrote:

The launch pad beneath the stool was destroyed during IFT

https://en.m.wikipedia.org/wiki/Launch_pad

"A launch pad is an above-ground facility from which a rocket-powered missile or space vehicle is vertically launched.[1] The term launch pad can be used to describe just the central launch platform (mobile launcher platform), or the entire complex"

You keep trying to say the launch pad was destroyed. The tower and the stool are all part of the launch pad. The launch pad was not destroyed. The vast majority of the launch pad received only light damage. Most of the damage was done to the concrete and the concrete underneith needed to be removed to run the water piping anyway. So this does not fit any meaning of the word destroyed.

That would be like saying your car was destroyed because it had a buckled wheel and you had already planned to replace the wheels next month. It's a non issue.

ANZUS340 wrote:

Was the launch a failure? Yes, of course it was in that the goals were not achieved. However, we can also be equally certain that valuable information was gleaned and much learned by this failure. Failure is part of the learning process. Too many fall for the slick tongues and bright eyes of billionaires.

Of course it depends on what the goal actually was. For myself, I suspect the goal was simply to expend the Booster and Starship they had on the pad, plus record whatever data they could along the way. Updates for Raptor, Starship, Booster, and Pad were already coming at the time of launch.

RJMAZ wrote:

https://en.m.wikipedia.org/wiki/Launch_pad

"A launch pad is an above-ground facility from which a rocket-powered missile or space vehicle is vertically launched.[1] The term launch pad can be used to describe just the central launch platform (mobile launcher platform), or the entire complex"

You keep trying to say the launch pad was destroyed. The tower and the stool are all part of the launch pad. The launch pad was not destroyed. The vast majority of the launch pad received only light damage. Most of the damage was done to the concrete and the concrete underneith needed to be removed to run the water piping anyway. So this does not fit any meaning of the word destroyed.

That would be like saying your car was destroyed because it had a buckled wheel and you had already planned to replace the wheels next month. It's a non issue.

This discussion has gone full bonkers, if people are reduced to disputing the definitions of words. Anyone who saw the IFT would plainly understand my meaning and the facts I gave. So I will leave it at that.

Avatar2go wrote:

This discussion has gone full bonkers, if people are reduced to disputing the definitions of words. Anyone who saw the IFT would plainly understand my meaning and the facts I gave. So I will leave it at that.

You continue to use strong language due to your personal dismay for SpaceX. You use words that are not in any official documentation or press release and try to pass them off at facts. These strong words are your personal opinion.

RJMAZ wrote:

You continue to use strong language due to your personal dismay for SpaceX. You use words that are not in any official documentation or press release and try to pass them off at facts. These strong words are your personal opinion.

Yes, they are my opinion based on observable fact. And have been confirmed in numerous articles and opinion pieces by knowledgeable and experienced engineers. But if it makes you happy, and will end this debate, I concede. Any image of the pad post-launch speaks for itself, in my view.

RJMAZ wrote:

Avatar2go wrote:

This discussion has gone full bonkers, if people are reduced to disputing the definitions of words. Anyone who saw the IFT would plainly understand my meaning and the facts I gave. So I will leave it at that.

You continue to use strong language due to your personal dismay for SpaceX. You use words that are not in any official documentation or press release and try to pass them off at facts. These strong words are your personal opinion.

Seriously, you Musk fanboys need to stop defending the indefensible.

speedygonzales wrote:

Seriously, you Musk fanboys need to stop defending the indefensible.

As much as I rag on Avatar, I consider him an honorable and worthy opponent.
Your post is flat out garbage that doesn't belong anywhere.

In the FAA environmental lawsuit, the judge has granted the SpaceX motion to intervene, but declined to issue summary judgement.

He asked the defendants to file a joint motion by July 31, and asked the parties to confer and propose an administrative hearing no later than August 14.

The internal center section of the new water-cooled steel plate is being installed on the Starship pad. It will be surrounded by a ring of external feeder plates to supply water from large pressurized mains.

https://twitter.com/NASASpaceflight/sta ... takTg&s=19

A report that SpaceX has not yet submitted any materials to the FAA for review of the launch mishap, nor taken any of the required public safety actions.

They continue to work on the launch pad refurbishment and are still projecting a second launch later in the summer.

https://www.cnn.com/2023/07/07/world/sp ... index.html

Here is the first test of the water cooling pad under the launch stool. It's consistent with pneumatic pressurization of the water reservoir (which is the mains surrounding the stool, I believe).

https://vxtwitter.com/NASASpaceflight/s ... 6556502016

Amazing, every word of what you just said was completely wrong.

Fewer engines are used because one big engine is cheaper and more efficient than two smaller engines.

Multiple engines are used when the individual engines aren’t powerful enough.

I would expect Starship to evolve towards greater efficiency with fewer, more powerful engines.

Heinkel wrote:

Avatar2go wrote:

No real comparison. A separation of 40 years in technology and design. N1 struggled from an inability to simultaneously and stably control that many engines. It's very possible with computer control today, to solve that problem.

I think there is a real comparison. The multiple rocket engines design was the Achilles heel of the N1 and is the Achilles heel of Starship.

A 33 engines rocket has a very complex fuel system to feed that many engines from one fuel tank and one oxidizer tank. And all these many engines have to work together in very close proximity, fixed to a structure, which is built as light as possible.

This causes lots of vibrations and interferences between the engines. Modern computer control helps but doesn't solve all these fundamental problems.

And simply from a statistical point of view, a 33 engine rocket has a 6.6 times higher probablity of an engine failure than a rocket with five rocket engines only. And the 33 engines design is not fail safe. Given the close proximity of the 33 engines, one single exploded rocket engine can ruin your whole day.

On Starship's last flight, the failure of six engines (18%) caused the end of the mission. That is like a four engined aircraft, which can't fly anymore, if one engine fails.

Wernher von Braun did very well, when he used just five rocket engines on the Saturn V.

eeightning wrote:

Amazing, every word of what you just said was completely wrong.

Fewer engines are used because one big engine is cheaper and more efficient than two smaller engines.

Multiple engines are used when the individual engines aren’t powerful enough.

I would expect Starship to evolve towards greater efficiency with fewer, more powerful engines.

Heinkel wrote:

Avatar2go wrote:

No real comparison. A separation of 40 years in technology and design. N1 struggled from an inability to simultaneously and stably control that many engines. It's very possible with computer control today, to solve that problem.

I think there is a real comparison. The multiple rocket engines design was the Achilles heel of the N1 and is the Achilles heel of Starship.

A 33 engines rocket has a very complex fuel system to feed that many engines from one fuel tank and one oxidizer tank. And all these many engines have to work together in very close proximity, fixed to a structure, which is built as light as possible.

This causes lots of vibrations and interferences between the engines. Modern computer control helps but doesn't solve all these fundamental problems.

And simply from a statistical point of view, a 33 engine rocket has a 6.6 times higher probablity of an engine failure than a rocket with five rocket engines only. And the 33 engines design is not fail safe. Given the close proximity of the 33 engines, one single exploded rocket engine can ruin your whole day.

On Starship's last flight, the failure of six engines (18%) caused the end of the mission. That is like a four engined aircraft, which can't fly anymore, if one engine fails.

Wernher von Braun did very well, when he used just five rocket engines on the Saturn V.

Wrong Jethro. Engine power doesn't scale with size. SpaceX chose the Raptor size before they started serious development because thrust to weight was best, even after adding in all the extra plumbing.
Very roughly, when you double the dimensions, engine thrust is proportionate to the square while engine weight is proportionate to the cube.
And they'd never be able to land the things if they didn't have many engines. You can only throttle down so far.

Another reason to use multiple smaller engines, is economic. You can then use variations of the same engine on all your stages, just more or less of them. That reduces the infrastructure, production, support, and control burdens, since all engines use the same basic architecture.

Today SpaceX has the B9 booster lifted onto the launch stool, and it's undergoing GSE and cryogenic testing.

A lot of people cite "inside sources" regarding the next Starship launch date.
They might all be telling the truth, despite the wide date range. SpaceX higher ups are a long ways from unified in their estimates.
I'm not sure what to hope for myself. If they launch earlier than October, I'll be on the wrong side of the planet and it will be the first Boca Chica launch or unplanned retirement I've ever missed.

I continue to believe IFT-2 will be in the 6-month timeframe from IFT-1, which puts it around October. In the past, SpaceX has not reported to the FAA or requested a launch license, until they are pretty sure they are ready to launch. So I think that will be a strong indicator.

It's also typical of SpaceX to not consult with the FAA, but instead submit their final plans for approval. FAA has said this month that they have received neither the mishap report nor any information about the ongoing activities at Boca Chica.

From that I would guess SpaceX will have already done most or all of the remediation work before they submit the report, seeking only approval and the launch license. The FAA will then need some time to review it, possibly with some back & forth.

Confirmation today from the FAA, they still have received nothing from SpaceX on the mishap report or the Starship/Starbase modifications.

“The FAA will not allow a return to flight operations until it determines that any system, process, or procedure related to the mishap does not affect public safety or any other aspect of the operator’s license,” the spokesperson said. “The mishap investigation is ongoing.”

https://www.expressnews.com/business/ar ... 261658.php

This is not surprising. The FAA will not want to be blamed for NASA and the USA not making it to the moon.

The FAA is now being blamed for the 737MAX and 777X delays. It is pretty clear that the FAA had and still has insufficient staffing levels. For the past 10 years the FAA were simply passing the results of the OEMs without checking.

Now the pressure is on the FAA as they have to actually do their job. The FAA is now the bottleneck for all US aerospace programs.

RJMAZ wrote:

Now the pressure is on the FAA as they have to actually do their job. The FAA is now the bottleneck for all US aerospace programs.

Note the articles state that SpaceX has not submitted the required mishap report or data to the FAA. Thus it cannot be an FAA issue.

Here is video of the water cooled steel plate testing today, at full pressure. It answers one question about water impinging on the engines, all the water is ejected towards the sides, there are no streams directed straight up. It should be interesting to see the performance during a hot fire test.

https://youtu.be/bJwQTFsezJI

Here is footage of the IFT-1 launch from the NASA WB-57 observation aircraft. It gives a much clearer view of the stack at altitude, including the loss of the Raptors, the tumble, and the destruct sequence.

It does really show quite well that the propellant tanks were partially unzipped and streamed liquid for awhile after FTS activation, but the streams did not mix and combust as intended. That appears to be a function of the tumble itself, as the propellant streams had to enter the engine exhaust before igniting.

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