An always cool Falcon 9 launch (and other Space News)

[Uttamattamakin]

SUCCESS SUCCESS.  I would call this what a Successful test at this stage looks like.  It got to space and most of the way back.  What Artemis needs is for Starship to do TWO things.  They need to demonstrate FULLY SUCCESSFUL REENTRY and landing for both a tanker version AND a human rated version.  Starship HLS is not meant to ever come back to Earth but landing on Earth will not be harder to land on that the moon since Starship needs a flat place to land.  On Earth we can make that happen.  

 

What I am hoping starship HLS will turn out to be is not a Starship as we've seen it but an item made for space... made to go up and stay up and transfer people to and from the Moons surface  I doubt we'll be seeing a Flash Gordon pulp sci fi looking rocket on the Moon.  The streamlined shape and casing just aren't required in space. 

Even Thunderf00t had to give it to him.  

 

[wanderingfool2]

25 minutes ago, dalekphalm said:

Starship was officially lost during re-entry but that was also expected.

The pez door didn't seem to properly close [I'm wondering if that's the reason they decided to skip the engine relight...or maybe they decided against it after what happened to the booster].

 

Nice to see the boostback for the booster work correctly (I think you could see the starship in a few of the booster camera views as things happened).  It's unfortunate they didn't have a softer water landing, I'm wondering if there was some type of issue with their software design for the return (after all they never really would have been able to properly test it).  The reason I'm guessing this is that you have the one gimble engine light, but you had 2 other non gimble engines light [right around the time they experienced the instability].  So I'm wondering if either they had initial issues lighting and what we witnessed was the software trying to compensate by firing 2 other engines or if maybe the return burn had instructed the wrong engines to light.

 

Booster seems like they might be able to fix it though, if it was an issue about too little fuel remaining they could change up the flight a bit.  I'm thinking that maybe they were intending to do the relight a bit earlier in the decent because the grid fins I don't think were meant to handle keeping it stable at those speeds in full atmosphere.

 

One thing, iirc this boosters grid fins actually went back to close to the original design [not that it would make any difference]

 

31 minutes ago, dalekphalm said:

Damn - the camera feed of the de-orbit is insane. You can see the plasma form in HD. The maneuver doesn't look like it's going properly but I'm going to wait until there's a debrief before I comment on what I'm seeing. It's crazy how the signal is holding strong throughout the re-entry. Looks like they've stabilized. So far so good. Video keeps cutting out but that's expected.

That plasma was so cool to watch.  With how the camera began overheating or whatever it was was interesting to see as well (with the feed going on).  I'm wondering if they didn't have quite as much control as they hoped for with the flaps (it seemed to not be keeping the ship in correct orientation).

 

Although if the Pez doors didn't close, I wonder if that would have caused the issue.  From my understanding they have to form a partial seal in order to partially repressurize the cargo bay to maintain structural stability.  If it failed to close it might have met it's fait by folding itself during re-entry. [All speculations at this time].

 

Lots of what looked like foam as well when it started entry, so I'm wondering what sections those came from.

 

Overall a good flight, if the propellant transfer was successful they actually will have passed the NASA milestone (which means it's worth $53 million).

 

 

So here are my official guesses from watching it once, booster failed to preserve enough fuel for engine relights/didn't plan for the forces that quickly where they will do a second decent burn in the future to reduce the forces [or some way to reduce the velocity before hitting cloud height]...I think they might have underestimated the speed it would return.

 

Upper stage, I think the door not closing correctly might end up being one potential cause since it could snap during re-entry; but I'm on the fence I think they had maneuverability issues which might have caused the issue.

[wanderingfool2]

Adding on a bit, after rewatching part of the broadcast

 

With the Raptor 3 engines (or at least from what it appears it was hinted those would be the changes), it should be able to carry 150 - 250 tonnes of payload to orbit.

 

For perspective, the lower lift capability is 50% higher than the previous reported number and, 66% higher for the upper bound. [when measuring the baseline as the original].  It's a good thing in that refueling now could potentially be reduced by a factor of 2x (depending on how it was calculated before).

 

For perspective, 5 starships carry enough mass to fully refuel a Starship in space [50 tonnes extra fuel]...of course there will be boil off but even if you assume 20% that means only 6 starships to fully fuel.

[manikyath]

3 hours ago, Uttamattamakin said:

They need to demonstrate FULLY SUCCESSFUL REENTRY

it was "assumed" ahead of time that this starship wouldnt make it back, because it was still using an older method of attaching the heat shield.. so in a sense IFT3's re-entry was a test of just how well the starship can cope with potential missing tiles. i once again introduce you to the concept of iterative design.. figure out going up first, then figure out coming down.

 

3 hours ago, Uttamattamakin said:

What I am hoping starship HLS will turn out to be is not a Starship as we've seen it but an item made for space..

this is exactly why we dont need:

3 hours ago, Uttamattamakin said:

a human rated version. 

 

also, at this point i do want to add this quote from earlier in the thread, because it feels ever so valid now..

On 11/19/2023 at 9:16 PM, Uttamattamakin said:

 There is a reason the one big rocket with a lot of small engines approach hasn't worked for anyone yet.  

not only did it work, this massive piece of steel managed to do a flip and burn (part of SpaceX design goal to eventually do RTLS on the booster) after hot staging, and then did a landing burn. the booster defenately didnt come back "smooth sailing", but it was a pretty solid attempt.

 

then starship itself did all the necessary "demo" stuff: payload door, prop transfer, lighting an engine in space.

it then did a re-entry, which essentially only served as a way to provide SpaceX with the data of how well the thermal protection and ship itself held up trough re-entry. 

 

that all aside, NSF made an "all the angles" video that's a collection of all vareous cameras they had pointed at the scene:

 

[Uttamattamakin]

17 hours ago, manikyath said:

 

 

This was a fully successful test in my book for getting the rocket system into space.  Now we need to see it work as a functional system.  It has to accomplish Dear Moon, AND Artemis missions. These have deadlines.  We need to see an All up test for a human rated HLS,  Then that same basic craft will have to take the Dear Moon mission and an Artemis landing.  

 

We also need to see it go all the way without exploding.  Space X has with great force managed to find a second solution to a solved engineering problem by using many engines.  It remains to be seen if that really is a better idea though. 

[manikyath]

3 hours ago, Uttamattamakin said:

Now we need to see it work as a functional system.  It has to accomplish Dear Moon, AND Artemis missions. These have deadlines.  We need to see an All up test for a human rated HLS,  Then that same basic craft will have to take the Dear Moon mission and an Artemis landing.  

yes.. and none of this involves landing a human rated starship. it involves a HLS (which will be based on but not be starship, in the same way as SLS is not shuttle, despite sharing A LOT of it's DNA.) 

 

i'm quoting you on the things you get wrong, like this:

3 hours ago, Uttamattamakin said:

Space X has with great force managed to find a second solution to a solved engineering problem by using many engines.  It remains to be seen if that really is a better idea though. 

artemis used 4 main engines and two SRB's.. which is less, but quoted costs are literally 1000x higher, even if starship misses it's cost goals by 100x, it's still a 10th of the price of SLS.

it is very much not a "solved" problem if you can, trough a different concept, create a rocket that'll cut "at least one digit" off the price. you apparently cant see that -maybe- there's more ways to do things. internal combustion engines were "solved" in the 60s.. yet since then we have made HUGE advancements on internal combustion on all fronts:

- efficiency

- emissions

- power output for a given size

- weight

and while you can sit here kicking and screaming claiming that your analogy to a V8 big block is great.. the V8 big block is a horrible idea in the majority of road vehicles, including trucks (which choose straight-6 for maintenance considerations)

 

it's not because your solution "works", that you've now solved the problem in an "absolute" way. having "a" solution doesnt mean you have "the" solution in the real world. i'll ascribe your short-sightedness in this regard to your affiliation with an entity that might not be faring too well in a more "open for new ideas" space market.

 

case in point.. you've been relatively positive about rocketlab earlier in the thread... a company who:

- uses ideas that are more ridiculous than starship (one solid section of carbon fiber for their hull, and electric pumps with batteries that they jettison in sections as they drain.)

- has actually lost close to 10% of their payloads. (not missions, customer payloads.)

 

you're just mad that they're making efforts that make NASA seem old fashioned, trough means that NASA didnt dare to do, at pricetags NASA couldnt even dream of achieving. there'll never be a launch outcome for starship where you wont be negative in your outlook if you INSIST on using terms like:

"force managed to find"

"second solution to a solved problem"

and

"remains to be seen"

for a project that's below 1% of the cost of SLS, and is on a MUCH faster development path. even if it takes them 6 more years and hundreds of billions of dollars to reach their goals.. they're on a better trajectory than SLS. unless proof to the contrary is provided, it looks like in a few years, between starship or SLS, the only reason to use SLS will be because government entities like to keep some things in-house (with good reason, mind you.. i'm not denying that).

[Uttamattamakin]

9 hours ago, manikyath said:

yes.. and none of this involves landing a human rated starship. it involves a HLS (which will be based on but not be starship, in the same way as SLS is not shuttle, despite sharing A LOT of it's DNA.) 

Yeah like I said earlier.  Having the HLS be some kind of ... Flash Gordon looking rocket wouldn't make sense.  The thing is designed to stay in space once it is up so streamlinging it beyond a certain point is a waste of time. 

9 hours ago, manikyath said:

 

i'm quoting you on the things you get wrong, like this:

 

I'm not wrong about those things.  Space X finally got this thing to work once and not blow up.  That is SUCESS SUCCESS for sure but there are still real problems which are rooted in the design choices I and others criticized.  All the space focused creators I have watched have pointed out those problems.    

 

For example fuel slosh may still be a factor in why super heavy's engines did not re-light.  There are still things that need to be re-jiggered a bit before it is really going to be ready.  At least in principle they have shown that such work won't be a waste of time.  

 

It's worth a try.

[manikyath]

6 hours ago, Uttamattamakin said:

I'm not wrong about those things.  Space X finally got this thing to work once and not blow up.  That is SUCESS SUCCESS for sure but there are still real problems which are rooted in the design choices I and others criticized.  All the space focused creators I have watched have pointed out those problems.    

they have made it work just as many times as sls, there is no reason to suspect SLS is now a proven known value while in the same breath you would suspect starship to turn out deeply flawed.

 

and again... "the space focused creators you have watched" - the people i watch have been covering launches since the days of a written blog covering shuttle launches. they ofcourse have concerns about what goals starship stillo needs to rach, but they see no reason why spacex would not be able to reach them.

 

I'm sure that if you went to look up any of these outlets back when they were covering the early days of falcon, they would have been highly critical of this unproven commercial space entity and their wild ideas. fact of the matter is (and NSF does refer to this occasionally) that SpaceX has proven they can trailblaze radically new ideas, bring them to market, and turn them into highly reliable services. people being critical at an early stage of development doesnt have any implications for how the design would be somehow deeply flawed, and you've yet to show me any evidence that it would be flawed past your own opinion on the engine count.

 

which.. about that...

7 hours ago, Uttamattamakin said:

For example fuel slosh may still be a factor in why super heavy's engines did not re-light.

so.. it was a factor when the rocket was going down vertically trough atmosphere, but wasnt a factor during the flip, y'know.. where fuel slosh would be an issue.

now.. i could be wrong, but my limited education in fluid dynamics says that fuel slosh happens when an object is making large movements, not essentially going vertical at terminal velocity.

ascribing the failed landing burn to fuel slosh without any sort of reasoning behind it is nothing more than your shallow preferences for one solution over another. wich, just to remind you... landing the booster is a SpaceX thing to cut costs per launch down to that "0.1% of the cost of SLS", it is in no way required for the HLS contract.

 

to just remind you again, in a big font this time, nice and separated out, just so you get why SpaceX is tossing out conventional knowledge to "re-invent" a better wheel;

 

0.1% the cost per launch of SLS.

[Uttamattamakin]

This may not have been a SUCCESS SUCCESS

 

6 hours ago, manikyath said:

they have made it work just as many times as sls, there is no reason to suspect SLS is now a proven known value while in the same breath you would suspect starship to turn out deeply flawed.

 

SLS is built on the technology of the Space shuttle not to mention that most rockets in operation have gone with the relatively few larger engines approach. 

 

You might want to watch this video by Space X fans.  It speaks about the failure of the re-lighting of the engines.  This is still an issue of the greater complexity of a system of many many engines.  More parts more problems.   

 

This is not a matter of what rocket one is a fan of or whatever.  I want a successful Artemis mission.  If SLS was not ready to go and Starship was I'd be critical of SLS. 

 

Here is another BIG fan of Space X who seems to say the test was not succesful ENOUGH for Artemis.  Since the test did not go perfectly by FAA standards it is a mishap. 

 

 

[manikyath]

1 hour ago, Uttamattamakin said:

 

most rockets in operation have gone with the relatively few larger engines approach. 

most rockets in operation? name them.

 

i'll name some "many engine" rockets:

- rocketlab electron uses 9 *tiny* engines on the first stage. like actually "you could put one on your desk" tiny.

- SpaceX falcon 9 uses, as the name implies, 9 merlin engines on the first stage.

- SpaceX falcon heavy uses 9x3 merlin engines, for a total of 27 engines.

- debatable if soyuz counts, they have quite an exotic design, see sidenote below.

 

as for upcoming stuff:

- rocketlab's upcoming "neutron" design currently also has 9 engines on the first stage

- SpaceX's upcoming "Starship" has 33 raptor engines on the super heavy booster.

 

now.. all of these have a pretty major design choice they all share: no solid rocket boosters.

it's almost as if some things are related here.. maybe SLS can get away with 4 liquid fuel thrusters because the SRB's carry over 75% of it's thrust on the pad (that's on NASA's fact sheet). that means that each of the 4 engines on SLS provide less than 6% of the total thrust on the pad.

 

sidenote.. what the heck is soyuz even.. on paper they're 5 engines with 4 combustion chambers each.. and a collection of 12 smaller thrusters for steering.

but really.. depending on how you count, we're looking at somewhere between 17 and 32 thrusters here.. and soyuz is pretty much *the* most proven launch vehicle on the market.

 

and all of this is completely irrelevant because.. news flash..

 

many thrusters isnt a problem, superheavy booster has made it up to hot staging twice with zero issues, the uphill portion hasnt been an issue since that one time they rapidly disassembled the launch pad. and the downhill portion is of no effect to artemis. big rocket go up is the goal, big rocket come down is a cost cutting bonus.

 

1 hour ago, Uttamattamakin said:

If SLS was not ready to go and Starship was I'd be critical of SLS. 

is this the place where i remind you that SLS is 6 years late, and work on starship didnt begin until after that 6 year delay in SLS's first launch?

 

as NSF has talked about before (and no, i'm not gonna delve into their hours upon hours of artemis ramblings) atemis's reliance on starship is NASA's "fault", SLS is way late, SLS cant provide all of the launch capabilities they want, SLS cant reach the budget goals they want. if you really delve into the time scale of "NASA returning humans to the moon" the most obvious answer is that using a launch partner is almost an "afterthought" because it eventually occurred to them that given the budget and timeframe they had no other option.

 

just to remind you; SLS is quoted to cost about 4 billion per launch, which is more than the 2.9 billion they awarded to SpaceX for the entire HLS programme.

 

oh, and while researching i found this statement, that nicely explains what these IFT flights are:

(hint: "T" stands for "Test")

Quote

NASA Office of Inspector General noted that SpaceX's philosophy involves extensively testing and flying their vehicles as early as possible—made possible by rapid in-house manufacturing capabilities that provide a steady stream of hardware—to aggressively reduce risks and acquire flight data.

[Uttamattamakin]

20 hours ago, manikyath said:

most rockets in operation? name them.

 

Pretty much every rocket except the ones you named.  Especially the man-rated ones.  Soyuz and Falcon 9 being exceptional.  

Also note Soyuz does something I said that Starship should consider instead of one big complex system of plumbing for all the engines, break it down in to smaller complexes of engines to get the best of both worlds without the cost of complexity.  

[wanderingfool2]

1 hour ago, Uttamattamakin said:

Pretty much every rocket except the ones you named.  Especially the man-rated ones.  Soyuz and Falcon 9 being exceptional.  

Also note Soyuz does something I said that Starship should consider instead of one big complex system of plumbing for all the engines, break it down in to smaller complexes of engines to get the best of both worlds without the cost of complexity.  

Starship's plumbing isn't really all that complex.  It's essentially a giant manifold attached with a few pipes [effectively].  Soyuz on the other hand has to essentially flair out its butt to make it all work out.

 

Starship actually has a pretty simple design if you think about what it's intended to do, i.e. have enough maneuverability to hover and do a controlled land...and honestly that's what adds the most complexity to the Starship.

 

The maneuverability is what has effectively cost them on the first 2 IFT's.  1st one hydraulic fire and loss of gimble; 2nd likely a hydraulic fire that's a result of the oxygen dump.

 

 

 

The issue I have is you have been shouting to anyone who would listen that many engines = bad, and acting like everyone does it.  The simple fact is the 2 most successful rockets in history have been ones with many engines.

 

 

Even if you want to compare it to others.  Shuttle, which effectively had 5 when you include the SRB's, actually had plumbing that failed that cost the life of Astronauts.  Saturn V [actually Apollo 6 had an engine failure which is a good example why many engines is good]; but Saturn V still had 5 on the lower stage.

One reason why they went with bigger engines is because manufacturing engines at that time was a major issue (they effectively electroplated to the final size).  SpaceX has chosen the manufacturing side first, that's what SpaceX is engineering effectively...how to manufacture it cheaply and to reuse the product.  The engines back then would literally take many months, no matter how many you built and a failure in one would mean months of waiting.

 

You seem to also forget you can only get so much performance/scaling with an engine, and a single larger engine makes it nearly impossible to do what they intend to do (i.e. land it, and reuse it).  Smaller engines are capable of throttling down to a lower amount [and even then Falcon 9 with 9 engines has an issue].  Seriously Falcon 9 has to do a suicide burn because they can't throttle down the engines enough to do a hover maneuver...a few large engines would make what SpaceX wants to do impossible.

 

Small engines also means quicker prototyping and development (back to not taking months to complete).  As a result we are entering into Raptor 3 revision soon, which is only 3x less power than the engines used on the Saturn V while achieving a thrust to weight ratio of like triple...i.e. more payload carrying capabilities

 

 

Your whole argument of many engines being bad effectively doesn't hold up when you look at it.  Yes the "plumbing" is simpler with 3 engines, but I could make that same argument to reduce it from 3 down to a single one.  If your whole idea of less engines is viable then why didn't they make just one...after all they had to fine tune each engine on the shuttle and others to not create a harmonic which would amplify the oscillations leading the destruction of the vehicle

[manikyath]

2 hours ago, Uttamattamakin said:

Pretty much every rocket except the ones you named.  Especially the man-rated ones.  Soyuz and Falcon 9 being exceptional.  

name them, because between SpaceX, rocketlab, and soyuz, i'm pretty sure i caught the great majority of launches in the past 5 years.

2 hours ago, Uttamattamakin said:

Also note Soyuz does something I said that Starship should consider instead of one big complex system of plumbing for all the engines, break it down in to smaller complexes of engines to get the best of both worlds without the cost of complexity.  

souyz is also a 60 year old design, the treshold of "cost of complexity" has changed A LOT in that timeframe.

besides the obvious technological advances made over the past 60 years, soyuz is also essentially an ICBM adapted for human and freight transport. it was *a* solution that worked, and has been extremely reliable in any weather, as you'd expect from an ICBM.. but that doesnt mean plumbing all those engines into a single thank then cant also be a viable option..

 

which.. i'm gonna reiterate again:

22 hours ago, manikyath said:

many thrusters isnt a problem, superheavy booster has made it up to hot staging twice with zero issues, the uphill portion hasnt been an issue since that one time they rapidly disassembled the launch pad. and the downhill portion is of no effect to artemis. big rocket go up is the goal, big rocket come down is a cost cutting bonus.

 

and likewise.. i'm gonna suggest you look into N1, because it really appears that the number of engines had nothing to do with the problems it had.

 

you can keep shouting nonsense, but if i can come with examples and you cant, i'll just have to assume that what you're shouting is in fact nonsense.

 

and just to make sure you dont accuse me of talking nonsense:

in 2023:

- 96 falcon 9 family launches

- 9 electron launhes

- 2 ariane 5 launches

- i'll count the one SLS launch in november of 2022, because otherwise NASA isnt on this list at all.

- 17 souyz launches

- 3 "long march" launches (that's china)

- 9 ISRO launches, on a variety of solid rocket booster configurations.

- 2 JAXA launches

 

fact of the matter is that every big ticket item on this list is either a 9 engine cluster design, pure SRB's, or the undecided quantity that is souyz.

 

while a cluster of 9 engines to a cluster of 33 engines is a big jump, SpaceX has clearly proven that the plumbing into a single tank isnt an issue, because for all 3 test flights none of the problems were caused by said plumbing. - in fact.. all i can find about N1's plumbing is the engine manufacturer blaming the plumbing for their engines blowng up.

 

as for the complexity of many rocket engines.. let's talk about the simplicity of many rocket engines.. or as someone responded to this photo below:

Quote

That’s three spaceX raptor engines, on a regular ass flatbed trailer, being towed around by a ford.

 

forget your special transports for spacecraft parts, having the engines this size and none bigger means you can actually deliver them "by the truckload".

[Uttamattamakin]

23 hours ago, wanderingfool2 said:

Starship's plumbing isn't really all that complex.  It's essentially a giant manifold attached with a few pipes [effectively].  Soyuz on the other hand has to essentially flair out its butt to make it all work out.

 

 

Your whole argument of many engines being bad effectively doesn't hold up when you look at it.  Yes the "plumbing" is simpler with 3 engines, but I could make that same argument to reduce it from 3 down to a single one.  If your whole idea of less engines is viable then why didn't they make just one...after all they had to fine tune each engine on the shuttle and others to not create a harmonic which would amplify the oscillations leading the destruction of the vehicle

I could write a reply to this... but I decided to farm it out to Microsofts CoPilot GPT-4.  Interestingly the cold unfeeling robot agrees with me on the essential issue of complexity.  Space X has their reasons for using many engines but there are SERIOUS drawbacks to it.  

Quote

Copilot

The debate over the number of engines in rocket design is indeed a complex one, with valid points on both sides. Historically, rockets have tended to use fewer, larger engines for several reasons:

1. Manufacturing Complexity: Larger engines were historically difficult to manufacture due to the technology available at the time. Fewer engines meant fewer parts to produce and assemble, which simplified the manufacturing process¹.

2. Reliability: Fewer engines can mean fewer points of failure. The Space Shuttle’s main engines, while fewer in number, were highly sophisticated and provided the necessary thrust without the need for a large number of engines².

3. Thrust-to-Weight Ratio: Larger engines have often provided a better thrust-to-weight ratio, which is crucial for the initial stages of launch where overcoming Earth’s gravity is critical³.

4. Combustion Stability: Larger engines have historically faced challenges with combustion stability, but once these were overcome, they provided a reliable source of thrust without the complexity of managing multiple engines².

However, advancements in technology and manufacturing have allowed for new approaches. SpaceX’s use of multiple smaller engines, for example, offers advantages such as redundancy, where the rocket can still perform its mission even if some engines fail. This approach also allows for more precise control during landing maneuvers, which is essential for SpaceX’s goal of reusability³.

It’s important to note that each design philosophy has its trade-offs and the choice often depends on the specific mission requirements and technological capabilities at the time of development. The success of SpaceX’s approach with the Falcon 9 and Starship suggests that multiple smaller engines can be highly effective when designed and implemented with modern engineering practices.

Those are just facts.  Yes all these systems have their issues.  Many many engines means more complex plumbing.  More parts means more points of failure. 

 

 

[Uttamattamakin]

23 hours ago, manikyath said:

name them, because between SpaceX, rocketlab, and soyuz, i'm pretty sure i caught the great majority of launches in the past 5 years.

I decided to respond to you with Copilot.  It is a robot and can be wrong but not biased.  I have struck out anything that is clearly wrong. 

 

Quote

Here’s a list of some notable orbital space rockets currently in use that have less than nine engines:

• Atlas V: Utilizes a single RD-180 engine for its first stage and can have up to five solid rocket boosters¹.
• Delta IV Heavy: Employs three RS-68A engines in its first stage².
• Falcon 9: Equipped with nine Merlin engines in its first stage³.
• Ariane 5: Features two solid rocket boosters and a single Vulcain 2 engine in the core stage².
• H-IIA and H-IIB: Both rockets use a single LE-7A engine in their first stage and a single LE-5B engine in their second stage³.
• Soyuz: The Soyuz rocket’s first stage has four RD-107A engines and the second stage has a single RD-108A engine².
• Electron: Rocket Lab’s Electron rocket has nine Rutherford engines on its first stage³.

These rockets are designed with a focus on reliability, efficiency, and specific mission requirements, which can influence the number of engines used. The choice to use fewer engines often involves trade-offs in design complexity, manufacturing, and performance characteristics.

It left out the very relevant to this discussion SLS.   4 SSME's and two boosters.  

Assuming we are only counting the first stages. 

 

23 hours ago, manikyath said:

...

I have come up with examples and given Space X credit where it is due for what they do right.  I am just not a fanboy for Space X.    I am a fan of rockets that are on time and don't blow up. 

[manikyath]

2 hours ago, Uttamattamakin said:

I decided to respond to you with Copilot.  It is a robot and can be wrong but not biased.  I have struck out anything that is clearly wrong. 

let's go trough the rest then:

- Atlas V: it has flown 99 times, has 17 more scheduled flights, and ULA is not selling any more flights.. it is therefore just barely "still in operation". it is also HUGELY aided by SRB's, supporting my previous notion that the number of engines might be more related to wether they want to rely on SRB's or not.

- Delta IV heavy: has flown 15 times, with one more flight scheduled before it's announced retirement. so.. again, just barely "still in operation".

- H-II is JAXA's (japan) SRB-only first stage rocket, i'm willing to debate if this should even be considered a "few engines" rocket, because it's basicly an advanced firework. cool tech, but irrelevant in the debate of number of engines, because clearly "no plumbing at all" hugely reduces the chance of plumbing issues.

 

this is also both less in number, and SIGNIFICANTLY less in number of launches than the "many engines" rockets.. do you want to correct your hilareously poor autopilopt response, or should i just assume that many engine cluters are 'at least just as viable' as few engines aided by SRB's?

 

2 hours ago, Uttamattamakin said:

Assuming we are only counting the first stages. 

as far as i'm aware, past the first stage just about everything is one or two engines.. aside from starship, which is unique in this regard because they are hoping to develop soft landing capabilities.

2 hours ago, Uttamattamakin said:

I am a fan of rockets that are on time

so, not a fan of SLS then? because you must have missed the previous douzen times i've mentioned that Artemis 1 launched 6 years late. i know you're just ignoring this fact for the benefit of your own argument, but i'm not. so whatever the case is, if the NASA contract says "moon by 2026", they have until 2032 before they're later than Artemis 1. i'm not saying this is a "free pass" on a 6 year delay, but if you are criticizing the chance for delays on starship, you cant then use SLS as an example of being on time.

 

2 hours ago, Uttamattamakin said:

I am just not a fanboy for Space X

that makes two of us.. i just happen to enjoy rockets that happen, i'm in it to watch cool technology happen, preferably more than once every few years. i like SpaceX because they launch a lot, and their development is very "visible" which really vibes with my engineer mindset. watching artemis 1 fly was cool.. but it was one flight. likewise i really enjoy rocketlab for their "style" of rocketry. their broadcasts are almost like they're playing KSP in real life, down to the gaming chairs and sponsored by logitech headsets.

[Uttamattamakin]

It is interesting how critical so many creators are of IFT 3 .  Having starship get to orbit, for all practical purposes ... and not blow up is great.  Getting superheavy most of the way back to a soft water landing was great.    This raises the bar and we need to see more complete success.   
 

Notice they mention the issues around fuel slosh and the complexity of the multi multi engine system that this is.  Re-lighting the engines is a problem.  They have to engineer around these fundamental physical issues. 

 

 

I am not ignoring what you have written.  The thing is you're just misssing my points.  I am talking about using ...as smart every day said... the playbook that Apollo left for us for how to get to the Moon.  So much about starships system for this purpose doesn't really make sense.  Firing a minimum of 7 of these to get 1 to the Moon... even if everything works perfectly ... by 2025 or  20206  forget it.  Never happen.  I WANT TO BE WRONG ABOUT THAT.  I HOPE I AM.  

7 minutes ago, manikyath said:

that makes two of us.. i just happen to enjoy rockets that happen, i'm in it to watch cool technology happen, preferably more than once every few years. i like SpaceX because they launch a lot, and their development is very "visible" which really vibes with my engineer mindset. watching artemis 1 fly was cool.. but it was one flight. likewise i really enjoy rocketlab for their "style" of rocketry. their broadcasts are almost like they're playing KSP in real life, down to the gaming chairs and sponsored by logitech headsets.

I can agree with this Space X flies a lot.  They are a great company that has accomplished many things.  I am a fan of Artemis and any company involved which does not keep up the pace for a Moon landing I am going to be critical of.  

They may work out all the kinks with Starship given enough time and enough money.    Meanwhile the PRC will be calming a "safety zone" around Shackleton crater (the closest thing in law to owning real estate on a celestial body.)   Without that ice and the insitu resources it will be a lot harder to build a real base on the Moon.  

[wanderingfool2]

2 hours ago, Uttamattamakin said:

I have come up with examples and given Space X credit where it is due for what they do right.  I am just not a fanboy for Space X.    I am a fan of rockets that are on time and don't blow up. 

Except you have been stating things that show you are being ignorant of what ACTUALLY is occurring, and misconstruing "facts". [And it really does bother me that in 15 pages you still choose to spell SpaceX wrong]

 

Name one rocket that was "on time".  Here's a hint, no modern rocket or really NASA funded endeavors have been on time.  So by your logic you aren't a fan of any rockets.

 

The simple fact again is that blowing up isn't a devastating issue, the newest private Japanese rocket blew up but I don't consider it a failure.

 

2 hours ago, Uttamattamakin said:

I decided to respond to you with Copilot.  It is a robot and can be wrong but not biased.  I have struck out anything that is clearly wrong. 

Have you not followed a thing in regards to LLM and their outputs.  They are 100% biased and can get many things wrong.

 

You are also "moving the goal posts" so to speak, as you have clearly emphasized as though no one else does lots of engines etc...and yet even in your list from copilot you struck out nearly half of them because they have above your 9 engine threshold.

 

Atlas V had 1 single engine, but there were 5 boosters that could attach to it to be capable of carrying larger payloads less than a Falcon 9.  You would need close to 8 SRB's to match the same payload as Falcon 9...actually you might need closer to 9 SRB, but that's a hypothetical because Atlas V can only handle 5 SRBs anyways.  So to get the same payload you would need over 9 engines.

 

Delta IV, yes it uses only 3 engines...but in Starship v3 expendable mode it will cost the same to fly if lets say SpaceX wanted a $100m profit on expendable launch [IFT-2 shows that it would be successful in an expendable mode mission already], and would carry close to 15 - 20x the capacity.  So while yes it has 3 engines it also is quite different states of existing.

 

IIB - Same kind of deal as Atlas V...requires SRB's and multiple (up to 4) to carry less mass to orbit.  If you wanted it to carry the same mass as a Falcon 9 could,  you would have to add in additional SRB's which would total closer to 9 total.

[manikyath]

3 hours ago, Uttamattamakin said:

Interestingly the cold unfeeling robot agrees with me on the essential issue of complexity. 

let's break down what your cold unfeeling robot has to say...

Quote

Manufacturing Complexity: Larger engines were historically difficult to manufacture due to the technology available at the time. Fewer engines meant fewer parts to produce and assemble, which simplified the manufacturing process.

your AI misquoted their own source.. they're on about how creating an engine with fewer parts simplifies the manufacturing process.

 

Quote

Reliability: Fewer engines can mean fewer points of failure. The Space Shuttle’s main engines, while fewer in number, were highly sophisticated and provided the necessary thrust without the need for a large number of engines.

again.. a misquoted source, it's a stackexchange discution (of all places to pull data from...) about the pros and cons of both sides, and the reasons to choose one or another. it's a shame your AI misquoted it because it's a pretty good read.

 

Quote

Thrust-to-Weight Ratio: Larger engines have often provided a better thrust-to-weight ratio, which is crucial for the initial stages of launch where overcoming Earth’s gravity is critical.

my job is safe, AI will not replace me.. because nothing in the quoted source evn talks about TWR, instead it talks about the reliability benefit of having more engines, and how modern computer technology allows us to control more complex rockets more accurately.

also - kinda funny.. the source YOU are quoting here.. is elon musk.

 

Quote

Combustion Stability: Larger engines have historically faced challenges with combustion stability, but once these were overcome, they provided a reliable source of thrust without the complexity of managing multiple engines.

same source as 2, same misquoting.. the only reference to combustion stability is a reference to car engines.

 

Quote

However, advancements in technology and manufacturing have allowed for new approaches. SpaceX’s use of multiple smaller engines, for example, offers advantages such as redundancy, where the rocket can still perform its mission even if some engines fail. This approach also allows for more precise control during landing maneuvers, which is essential for SpaceX’s goal of reusability3.

It’s important to note that each design philosophy has its trade-offs and the choice often depends on the specific mission requirements and technological capabilities at the time of development. The success of SpaceX’s approach with the Falcon 9 and Starship suggests that multiple smaller engines can be highly effective when designed and implemented with modern engineering practices.

this is exactly what we have been telling you.. and you now blatantly use it to somehow try and prove your own point? have you any idea how ridiculous this makes you look? have you not proof-read this at all?

 

45 minutes ago, Uttamattamakin said:

I am a fan of Artemis and any company involved which does not keep up the pace for a Moon landing I am going to be critical of.  

so.. NASA then? because the artemis contracts are historically tight timing-wise, presumably because of the 6-year delay from

 

NASA's own internal dealings.

 

45 minutes ago, Uttamattamakin said:

It is interesting how critical so many creators are of IFT 3 .

i think you mistake "being cautious with optimism" for being critical. now, i've only watched the final thoughts of the video you linked.. but i dont think they sounded critical at all.

45 minutes ago, Uttamattamakin said:

the playbook that Apollo left for us for how to get to the Moon.  So much about starships system for this purpose doesn't really make sense.  Firing a minimum of 7 of these to get 1 to the Moon... even if everything works perfectly ... by 2025 or  20206  forget it.  Never happen.  I WANT TO BE WRONG ABOUT THAT.  I HOPE I AM.  

apollo essentially got a bunch of "test subjects" to the moon and back in a tin can, as a physics person you ofcourse understand that if you want to get more than "just another tin can" to the moon, you'll need more energy. the goal of artemis isnt "put human on moon", the goal is to put ACTUAL science down on the moon, and be a pathfinder for further human spacetravel.

or to put it in a vaguely quoted clarkson quote from earler in the thread:

Quote

We've been to the north pole, now let's try to get to the north pole comfortably.

 

45 minutes ago, Uttamattamakin said:

They may work out all the kinks with Starship given enough time and enough money.    Meanwhile the PRC will be calming a "safety zone" around Shackleton crater (the closest thing in law to owning real estate on a celestial body.)   Without that ice and the insitu resources it will be a lot harder to build a real base on the Moon.  

enough time and money.. should i bring up the cost difference between starship and SLS again? and why do you think NASA isnt flying the whole party with SLS?

BECAUSE THEY CANT AFFORD IT.

 

wether you, or anyone else at NASA likes it or not, fact of the matter is that any chance the US has got at winning the modern era space race has to include their commercial launch partners, because they simply cannot do it on their own dime. NASA is too slow, too expensive, and too complicated of an entity to do revolutionary things. the reason why SpaceX is actively blowing up starship prototypes is because it's cheaper and faster to develop that way. two things NASA sorely needs, but cant do themselves for political reasons.

[wanderingfool2]

23 hours ago, manikyath said:

your AI misquoted their own source.. they're on about how creating an engine with fewer parts simplifies the manufacturing process.

As I also mentioned earlier, it's maybe not even about simplifying the manufacturing process but rather the practicality of the manufacturing process.

 

The cooling channels in the rocket main combustion chamber were effectively electroplated on.  The old school method was to create the inner portion, then use wax to fill up the channels and then electroplate to build up like a CM of metal surrounding it.

 

This wasn't used on the Saturn V however, but was used later on on things like the shuttle.

 

The Saturn V though, it used pipes to do it iirc, and at that stage it's about the validation required for each engine would take an inordinate amount of time if it was used...since to create 1 large engine it would be overall simpler to do the process a single time [and the benefit that the more volume gave a better weight to thrust ratio]...either way though both of these methods are obsolete with the advent of modern manufacturing process.

 

On 3/18/2024 at 11:29 AM, Uttamattamakin said:

I am talking about using ...as smart every day said... the playbook that Apollo left for us for how to get to the Moon

SmarterEveryDay's method lacks the awareness of modern rocketry, falls prey to hindsight, and is just as unrealistic as the current timeline is.

 

e.g. The SLS was one of those "playbooks" that congress ate up.  It was meant to be old proven technology that would save money and only cost $10 billion to make, be ready by 2015 and cost $500 million to launch.  It has cost over $23 billion, didn't launch until late 2022, and estimated at maybe upwards of $5 billion per launch [but probably at least $1 billion].

 

As I stated before as well, some of the documents he pointed to would have been classified at the time. There are mission updates, but the public isn't privvy to listening and seeing them.  They already have the testing underway for the starship to Orion dock being tested [and a prototype built]

 

Apollo also existed in the time when the peak budget was ~5%, which today no one would accept that kind of budget today.  Do you know why we stopped going to the moon?  Because it was too expensive to keep the Saturn V running and operating missions.  NASA is setting to accomplish this without breaking the bank, so no the "playbook" is not the same playbook.  The playbook this time is a sustainable mission to the moon.

 

If the Starship isn't ready for Artemis it won't be the fault of SpaceX, but instead it's the pencil pushers who decided to set a public target date that is unrealistic with the actual mission objectives.  It's the whole, don't start a bidding processing on something with only 3 years lead time.

 

Again, the SLS is the prime example of this kind of mentality, it was supposed to have missions by 2015 but didn't.  The Orion capsule was supposed to be in service in 2015 but wasn't.  The old playbook has failed.

 

On 3/18/2024 at 11:29 AM, Uttamattamakin said:

Meanwhile the PRC will be calming a "safety zone" around Shackleton crater (the closest thing in law to owning real estate on a celestial body.)   Without that ice and the insitu resources it will be a lot harder to build a real base on the Moon.  

No need to try making this into a discussion on politics.  The moon is an international body, and the whole combativeness of this country that country etc only leads to additional conflicts.  Space should not be an us vs them mentality, which is what you seem to be pushing

[Uttamattamakin]

2 hours ago, wanderingfool2 said:

SmarterEveryDay's method lacks the awareness of modern rocketry, falls prey to hindsight, and is just as unrealistic as the current timeline is.

The person who is an engineer invited to speak to Engineers at NASA knows less about rocketry than you.   

 

I mean me I'm just a humble theoretical astrophysicist working on a NASA space probe.  So, what do I know.  oki then. 

 

Ok smart guy Wandering.  You know everything about everything but never state any sort of credential to back it up.  Not even a claim of one.  Why should anyone believe anything you have said other than ... Gee whiz it would be nice if this was true because that means a world with really cool technology really soon. 

 

Don't get me wrong I sorely wish your optimism motivated reasoning was sound. 

 

[manikyath]

1 minute ago, Uttamattamakin said:

The person who is an engineer invited to speak to Engineers at NASA knows less about rocketry than you.  oki then. 

to be fair, the little of that speech i could bear to watch didnt really present as a man deeply involved with the intricacies of modern day rocket design. he might be an engineer, he might be knowledgable, but that doesnt make him an authority on the difference between NASA's design philosophy and SpaceX's design philosophy.

 

also - he's a youtuber, a guest speaker.. if he truly was an authority on the matter, why is he a guest speaker instead of an engineer at NASA? to me this felt like a cross-marketing opportunity for both parties. successful, a brilliant idea, a perfect person to light some fire under NASA's butts, but it doesnt make him an authority on the details of an incredibly complicated field. it's obvious to laymen like us, it should be obvious to you.

[wanderingfool2]

37 minutes ago, Uttamattamakin said:

The person who is an engineer invited to speak to Engineers at NASA knows less about rocketry than you.   

I mean me I'm just a humble theoretical astrophysicist working on a NASA space probe.  So, what do I know.  oki then. 

Seriously, learn to read and have an ounce of comprehension and honestly the way you proclaim your education you are much like ThunderF00t ego stroking.

 

I know master level computer science major who worked at Google who I talked to about Waymo before...his response to it was talking about the trolley problem and he seriously was considering that that was an important part of programming it [in the literal sense he had no knowledge of how self driving technology actually worked]

I had a prof who was pretty much illiterate when it came to using a computer, but he taught algorithm design.

I know CCNA's who deployed networks, and I had to come in and correct them on their mistakes [in one case having to show a POC that I wrote proving their setup didn't match the specifications].

 

General education, or even education in a field DOES NOT mean they are knowledgeable in aspects of the field...actually it can be worse in that you could have a very narrow field of focus.

 

Again, I said "lacks the AWARENESS of modern rocketry".  He didn't follow the rocketry and missions up to the point where he was asked to talk with them.

 

He pretty much admits it himself, that he wasn't even aware that it would require in-space refueling.  You can tell that his calculations on burn off are also off, more likely using early numbers of what Starship might have required to launch...because while the statement was 6, he talked about 12 (just still hinted he thought it was more).  Even at a boil off of 20%, the v3 Starship will hypothetically need a max of 6 ships.  Assuming 12 ships would assume a boil-off of roughly 50%.

 

The issue like above is exactly why someone who can have a higher educational background can be wrong when they lack the awareness of their current subject.  Again he's pulling papers and looking at things with hindsight knowledge of the inner workings of Apollo.

 

1 hour ago, Uttamattamakin said:

You know everything about everything but never state any sort of credential to back it up.  Not even a claim of one.  Why should anyone believe anything you have said other than

Degrees and "credentials" in the form of education don't mean anything you ignorant person.

 

It's logic 101, I've made claims, claims that are verifiable that can be tested against; I've made guesses of outcomes that are closer to what turned out to reality than you.

 

But hey you are the one who is to thick to realize your education doesn't mean a thing when you make stupid statements like [fuel slosh is why they never made orbit] and your stupid bits where you somehow think you are better than the people WHO WORK AT SPACEX..

 

To only rely on education merits as a standard is just stupid.

[Uttamattamakin]

16 hours ago, wanderingfool2 said:

Seriously, learn to read and have an ounce of comprehension and honestly the way you proclaim your education you are much like ThunderF00t ego stroking.

 

To only rely on education merits as a standard is just stupid.

Yet you idolize people who work at Space X.  I think this is as Sabine Hoseenfelder put it in a recent video.  People who think in an engineering sort of way have no real respect for theory development.  IF they can't put hands on it, or understand it after taking at most the initial three course sequence of physics they don't believe it.  

It's like how GREAT electrical engineers think gravity is fake, nuclear physics is fake,  and that everything in the universe can be explained by electricity.  

 

Much respect to SpaceX for what they have done with Dragon, Falcon 9, Starlink, and so forth.  Kudos for making a very hard to do system work more than it has before.   In fact I think that most of them would agree with me.  THEY ARE DOING SOMETHING REALLY HARD TO DO... so it is likely that it won't work BUT WILL BE GREAT IF IT DOES.  That using 9 larger engines, as on Falcon might be an easier solution. 

 

Just to check I asked Copilot to figure out how many Saturn V F1 engines would give the same thrust as superheavy.  It would take 11.  Just 11 engines.  So far fewer points of failure to contend with.  https://sl.bing.net/iAHzhJfvnYO  

 

It's only the fans of SpaceX that give me problems.  Never actual people who work with and for NASA who I deal with on a weekly basis.  Actual scientists never doubt that I know science when I speak to them. I wonder why that is.  (Yes I do somewhat relish and luxuriate in how that riles some people.  As if I didn't work really hard to get what little I have. ) 

Many of you talk about innovation and doing something really new and never done before.  That to me would be if SpaceX built a real practical Aerospike engine for this system.  Since these have the advantage of working at any atmospheric pressure or even in vacuum.
 

 

[wanderingfool2]

8 minutes ago, Uttamattamakin said:

Yet you idolize people who work at Space X.  I think this is as Sabine Hoseenfelder put it in a recent video.  People who think in an engineering sort of way have no real respect for theory development.  IF they can't put hands on it, or understand it after taking at most the initial three course sequence of physics they don't believe it.  

I don't idolize SpaceX people, but I'm calling YOU an ignorant person for making statements COUNTER to the SpaceX engineers with the truly crazy statement that you somehow know better than what was in the press release.  And the fact YOU are slagging profession.  We get it you are a theoretical person, your previous statements are still stupid theories that run counter to all the information that has been presented.  Your theory is equivalent of someone stating that the air is 99% oxygen, and people pointing to the nitrogen concentrations and you still stating that they are wrong and just a fanboy of the labs that ran the test.

 

You want to know the type of person Sabine is though, she's the type who lacks AWARENESS in the computer science field, presents the information anyways, and lacks integrity to correct her mistake.  Case in point, she confuses petabit with petabyte [literally in her thumbnail and title she uses the word byte instead of bits], for the first few days the video existed the top comments were all about her usage of bits and bytes almost interchangeably; and still no correction.  Talks about encryption on AI, yet is ignorant of the fact the way LLM's work [and similar advanced AI networks] mostly require non-encrypted information because it's not just simple transforms on encrypted data...the data itself needs to effectively almost "fit" a certain pattern and reasoning basis off the data it sees [I'm not going more into this because I'll start running up against a NDA, but processing on encrypted data would yield worse results and a whole lot less useful insights]

 

The point is stop holding up Sabine as though she is some sort of fixture, she makes mistakes and worse yet when she does make major mistakes in a topic she doesn't readily correct them.

 

After all you are the person making the kind of statement

  

On 2/25/2024 at 3:42 PM, Uttamattamakin said:

I get it you take Elons words and Space X press realeses as gospel.  I am going by what I saw in the data. The line that they almost got to orbit but for not having a payload makes no sense.  NONE.   Surely they would've factored that in. 

So again, your education means nothing if you are conceited enough to believe your word of SpaceX.

 

28 minutes ago, Uttamattamakin said:

THEY ARE DOING SOMETHING REALLY HARD TO DO... so it is likely that it won't work.  That using 9 larger engines, as on Falcon might be an easier solution. 

Please at least THINK before you try responding with something like this; because I'm getting tired of having to point out flaws in your silly theories

 

Falcon 9 uses smaller engines compared to Starship.

 

Falcon 9 has to use a suicide burn because it can't perform a hover maneuver.  In fact, if they don't light it/shutoff at the correct time it will either crash land or if it lands and doesn't shut off in time it will actually start flying again.

 

Again, if you read anything at all and actually comprehended what was said you will notice that the landing burn required would be a lot harder with large engines (because you won't be able to get the control needed AND you will be generating too much power).

 

You say it's an easier solution, but do you understand.  What evidence do you present because so far the engines you keep going on about weren't the root cause of the failure.  A lot of the failures have stemmed from the fact that the Starship is the largest thing ever to take flight and with that comes a learning curve...but again the engines weren't the problem.

 

IFT-1, actually would have been a scrub (as 4 engines weren't available at launch time, but they decided to fly anyways).  Had it been larger engines it would have been a scrub, and we would have had to wait longer.  Engines going out on IFT-1 and it was still able to fly for a longer period of time. [Actually larger engines would have resulted in less data]...actually had they switched to electronic gimbling [which they were going to switch to anyways] it's very likely we would have seen the flip maneuver occur and starship get to the Karman line.

 

IFT-2 , engines not the fault, "complex" plumbing (which really it's pretty simple plumbing) wasn't the issue, it was a blocked filter in the main tank which has nothing to do with many smaller engines as you still would need a similar design to the tank with a few engines and for the starship it was the oxygen dump (along with the hydraulic fire again).

 

So using larger engines isn't the easier solution.  ESPECIALLY since you can't seem to get it through your mind the GOAL IS NOT GET INTO SPACE.  It's GET INTO SPACE AT A LOW COST.  You are missing a great qualifier to the requirements.  You cannot easily create a large engine at a low cost.  Larger engines means a whole lot more specialized equipment, more road closures, slower replacement times, higher cost of manufacturing, higher minimum thrust [which is bad when trying to land the thing], and greater risk of a SPOF.

 

53 minutes ago, Uttamattamakin said:

It's only the fans of SpaceX that give me problems.  Never actual people who work with and for NASA who I deal with on a weekly basis.  I wonder why that is.  (Yes I do somewhat relish and luxuriate in how that riles some people.  As if I didn't work really hard to get what little I have. ) 

Because you label anyone who gives you a problem as SpaceX fans...seriously, go to all the people you work with and ask them to come here and back you up then in your assessment.  Or perhaps, just perhaps stop making asinine statements that are false.

 

1 hour ago, Uttamattamakin said:

Many of you talk about innovation and doing something really new and never done before.  That to me would be if SpaceX built a real practical Aerospike engine for this system.  Since these have the advantage of working at any atmospheric pressure or even in vacuum.

They are doing something new and never done before.  They literally brought ~5000 TONNES of mass into space.  Starship is also only the second methalox ship ever to fly into orbit.  The simple fact is it is attempting to do things never done before.  Starship created the largest mach diamonds ever as well [with the 33 engines all combining together to create giant mach diamonds]

 

Your video you posted about Aerospike, did you ever even watch it?  Here's a hint, Tory Bruno (ULA) talked about heat issues and such, Musk talked about not getting enough performance increase vs optimizing (keeping a simpler design), RocketLabs talking about the pricings and added complexity in engineering, and Vector Aerospace talked about the added weight/parts needed to do it pretty much offset the benefits.  So ultimately you have 4 companies that looked into it, and they all came to similar conclusions that it's not worth pursuing at the moment because the benefits don't outweigh the risks.