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

[manikyath]

1 hour ago, Uttamattamakin said:

Yet you idolize people who work at Space X. 

idolize < = > assume they know what they are doing better than some outsider with a degree and an opinion.

1 hour ago, Uttamattamakin said:

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.  

likewise, people who think in a very theoretical way have no real respect for the difficulties of executing ideas in practisce. if they cant pinpoint it as a variable, it simply doesnt exist. (sidenote, this is referred to as "an unknown unknown", and it's what the majority of engineering time tends to go to.)

THIS point drives home very well why you're getting so much headwind here, to not realise there's two equal and opposite sides to that argument is a perfect example of how shallow your own thinking is.

 

1 hour ago, Uttamattamakin said:

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.  

ellaborate, provide example, please support this statement with anything other than a james may-esque "i dont believe in magnetism" joke, from anyone who has any credibility to be quoted. it might not have occurred to you - but engineers love to joke about everything.

at my place of work we have very in-depth theories about how the colour of a PCB affects the reliability.. which is ofcourse utter nonsense, it's just that not all manufacturers have the same quality standards, but it's funny to blame the colour.

 

1 hour ago, Uttamattamakin said:

In fact I think that most of them would agree with me.  THEY ARE DOING SOMETHING REALLY HARD TO DO..

up until here i'm following you with that thought...

1 hour ago, Uttamattamakin said:

so it is likely that it won't work BUT WILL BE GREAT IF IT DOES.

here you're just falling into your theory pit again.. they're engineers, if the current iteration doesnt work, they will iterate until it works - "iterative design" and "rapid prototyping". go look that up, it might make sense to you one day.

also - i dont think anyone with a key role in the Starship thinks it's likely it wont work.. since it essentially already works "as a rocket", it's just the landing portion and the payload portion to add on top of that to finish it off.. and by my calculations they still have 6 years before they're more delayed than SLS

 

1 hour ago, Uttamattamakin said:

That using 9 larger engines, as on Falcon might be an easier solution. 

deer lord.. page 4 all over again.. there's a lot of practical, real-world issues with making fewer bigger engines. you wouldnt understand because you're stuck in your theory course, but even just yesterday's point about "these engines fit on a regular-ass flatbed truck" is a major factor for something that will be - for the scope of a rocket - mass produced.

 

1 hour ago, Uttamattamakin said:

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  

oh, and copilot did such a great job before.. but i'll entertain your idea..

- less points of failure, but also less redundancy.

- i havent measured this.. but based on images i have a strong feeling 11 of these dont fit under starship. or is that too practical for you?

- it would be more difficult to transport and attach 11 of these than 33 raptors. that's a key part of raptors: they're mass producable and 'easy' to swap out. (all statements relative to the field of rocketry)

- if that engine is relevant to starship, why isnt SLS flying on them?

- you keep shouting 9 engines.. and the best example you could come up with ends up at 11.

 

1 hour 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. 

because people you interact with might share your beliefs, and/or dont get called dumb fanboys by you on a daily basis.

1 hour ago, Uttamattamakin said:

Actual scientists never doubt that I know science when I speak to them. I wonder why that is.

because you havent said anything that you could support with any facts along this entire thread. dont make this a sob story now.. we're not attacking you personally because of any trait of yoruself, other than your absolute determination to be incorrect in this thread.

 

1 hour ago, Uttamattamakin said:

As if I didn't work really hard to get what little I have.

none of us here have claimed that, it's not what we're here for, we dont know your situation and we dont care about your situation. we're here to talk about big rocket go up is cool. stop trying to victimize yourself.

 

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.

aerospikes are also very troublesome in the real world (see, here comes reality again.. pesky reality.), and the efficiency benefit is largely offset by the fact that there's very few usecases where a single engine needs to perform from ground level to space. when we go SSTO perhaps, but not on a multiple stage heavy lifter.

 

afaik last time i saw an aerospike it was on some crew SSTO concept that was deemed too complex to make financial sense at the time.

 

i'd dare make a guess that SpaceX will never develop an aerospike engine, because the upfront investment will most likely not match the profitability compared to making engines with an atmosphere version and a vaccuum version. or should i remind you again - SpaceX is a for profit rocket corporation, not a research facility.

 

besides.. i'd argue that making things orders of magnitude cheaper is quite an innovation.

[wanderingfool2]

1 hour ago, manikyath said:

oh, and copilot did such a great job before.. but i'll entertain your idea..

haha, I know right.

 

Don't forget 11 F-1 engines also would weigh an extra ~40 tonnes...so expected payload to orbit would be reduced by about 40 tonnes.

 

Also F-1 engines minimum thrust  at it's lowest can only be ~65%.  [1 M lbf where you got combustion instability, as per https://www.enginehistory.org/Rockets/RPE08.11/RPE08.11.shtml] Or roughly 4,448 kN.

Now here is just a bit of AI goodness then.

Mass of booster, without fuel is ~3,600,000kg [~* 9.8 to get kN]...to hover you need ~35,280 kN.

With F-1 you need 5.2 engines to match that weight (no acc./dec.).  That means you need to light at minimum 6 engines.

Now what is the max number of engines you can light to hover.  7.9, now the issue is 8 would produce too much thrust [also you wouldn't be running all engines a pure minimum].  So you end up with 7 engines max you could light.  Or 6 - 7 engines needed for a hover maneuver.

 

This is where the issue starts to come into play, which is similar to what Falcon 9 experiences (and why Falcon 9 does a suicide burn).

You could have a range of thrust with those 6 - 7 engines as follows: ~26,688 kN - ~47,390 kN.  Since the weight is 35,280 kN though the min it would be would be 35,280 - 47,390.

 

So you wouldn't want to light the minimum, but rather light the maximum...so lets say you light 7; and 1 fails to light.  You will have an imbalance in thrust from one side, so you need to reduce the power on the other engines (equal to 1 engines worth).  That means failing to light a single engine could cause the loss of vehicle.  Because the range is only 6 - 7 engines you effectively have no wiggle room when it comes to underperforming  or failed relights.

 

So a single engine relight will effectively end your mission (and larger engines have the same if not maybe more changes of failing).

 

Lets look at the Raptor engines now though, lets even assume for the calculation that it had the ~65% pitfall (although raptors can do at worst 50%, but lets assume 65% which is in F-1 argument favor).  That's 1,485 - 2,260 kN 

 

Min engines required, 15.6, so 16 engines.

Max engines possible, 35280 23.7 engines; so rounding down to 23 [remember in actuality, based on the true specs, they could have 30 engines and hover]

That means the min to max range is 16 - 23 engines with a usable range of: 23,760 - 51,980

 

Notice how it allows for an extra of ~4.6 mN of wiggle room.  Also note that you can lose ~7-8 engines of thrust before an issue...going like above that means you could lose 3 - 4 engines [with balancing out the load] and still maintain within acceptable range.

 

So Uta I think the above shows the point everyone is making, that you fail to see, more engines = better resiliency when things go wrong.  The booster is capable of returning with 4 engines failing (over 10% engine loss).  That is something a large engine is unable to do...in-fact large engines makes it worse in the sense that you lose a lot more fine grain control.

[manikyath]

interesting watch, and ironically it happens to compare raptor to F1.. didnt even go to look for this and i just happened upon some sources relevant to the current debate..

i could summarize, but it's just a good watch for the entire 18 minutes.

[Uttamattamakin]

21 hours ago, manikyath said:

interesting watch, and ironically it happens to compare raptor to F1.. didnt even go to look for this and i just happened upon some sources relevant to the current debate..

i could summarize, but it's just a good watch for the entire 18 minutes.

I'll give it a look.  I know F1 is NOT how we'd build an engine now.  

 

I hope Space X's plans pan out it'll be great if they do.  I just don't like so many points of failure which when they fail they explode.   

 

23 hours ago, wanderingfool2 said:

haha, I know right.

 

Don't forget 11 F-1 engines also would weigh an extra ~40 tonnes...so expected payload to orbit would be reduced by about 40 tonnes.

Yeah I know even bringing them up makes me feel like an old senator who wonders why we don't build big gun battleships anymore. 

 

23 hours ago, wanderingfool2 said:

 

Also F-1 engines minimum thrust  at it's lowest can only be ~65%.  [1 M lbf where you got combustion instability, as per https://www.enginehistory.org/Rockets/RPE08.11/RPE08.11.shtml] Or roughly 4,448 kN.

Now here is just a bit of AI goodness then.

Mass of booster, without fuel is ~3,600,000kg [~* 9.8 to get kN]...to hover you need ~35,280 kN.

With F-1 you need 5.2 engines to match that weight (no acc./dec.).  That means you need to light at minimum 6 engines.

Now what is the max number of engines you can light to hover.  7.9, now the issue is 8 would produce too much thrust [also you wouldn't be running all engines a pure minimum].  So you end up with 7 engines max you could light.  Or 6 - 7 engines needed for a hover maneuver.

 

This is where the issue starts to come into play, which is similar to what Falcon 9 experiences (and why Falcon 9 does a suicide burn).

You could have a range of thrust with those 6 - 7 engines as follows: ~26,688 kN - ~47,390 kN.  Since the weight is 35,280 kN though the min it would be would be 35,280 - 47,390.

 

So you wouldn't want to light the minimum, but rather light the maximum...so lets say you light 7; and 1 fails to light.  You will have an imbalance in thrust from one side, so you need to reduce the power on the other engines (equal to 1 engines worth).  That means failing to light a single engine could cause the loss of vehicle.  Because the range is only 6 - 7 engines you effectively have no wiggle room when it comes to underperforming  or failed relights.

 

So a single engine relight will effectively end your mission (and larger engines have the same if not maybe more changes of failing).

 

Lets look at the Raptor engines now though, lets even assume for the calculation that it had the ~65% pitfall (although raptors can do at worst 50%, but lets assume 65% which is in F-1 argument favor).  That's 1,485 - 2,260 kN 

 

Min engines required, 15.6, so 16 engines.

Max engines possible, 35280 23.7 engines; so rounding down to 23 [remember in actuality, based on the true specs, they could have 30 engines and hover]

That means the min to max range is 16 - 23 engines with a usable range of: 23,760 - 51,980

 

Notice how it allows for an extra of ~4.6 mN of wiggle room.  Also note that you can lose ~7-8 engines of thrust before an issue...going like above that means you could lose 3 - 4 engines [with balancing out the load] and still maintain within acceptable range.

The above is all very good and informative. 

 

23 hours ago, wanderingfool2 said:

 

So Uta I think the above shows the point everyone is making, that you fail to see, more engines = better resiliency when things go wrong.  The booster is capable of returning with 4 engines failing (over 10% engine loss).  That is something a large engine is unable to do...in-fact large engines makes it worse in the sense that you lose a lot more fine grain control.

See my point below more engines means more explode things that when they fail... fail HARD and fast.  Given the track record so far Starship has a 2/3 chance of BOOM. 

 

I don't get why it is controversial to point out that Space X has seen a lot of catastrophic failures for a system we are supposed to rely on. 

[manikyath]

2 minutes ago, Uttamattamakin said:

I just don't like so many points of failure which when they fail they explode.   

and when one of SLS's engines fails it probably explodes too.. but if you have the capacity to shut down off-nominal engines before criticality (which starship's booster has) it's a boost for reliability figures... and in fact it's how the airplane industry works.

 

the 'points of failure' argument also only holds if you consider the reliability of the engine itself to be a known value to compare against. just to put some numbers behind this, we've seen two boosters reach the point of hot-staging, at which point we've essentially seen 66 raptor engines perform as expected during the critical part of the mission (landing isnt critical), which is more than the amount of RS-25 engines that were used during the entire lifespan of shuttle.

 

losing one engine (and the opposing pair for balance) also only means a 6-10% decrease in thrust (depending on pairs or triplets), which can be made up for by increasing power level on the rest, because it's been stated they have a quite decent headroom on them. if i recall they have some 30% of headroom that eventually leads into "engine-rich exhaust" (yes, every term here is a meme.. welcome to engineering) where they quite literally sacrifice engines to save the mission.

 

to me it's interesting how some very expensive problems of rocketry are resolved with surprisingly simple concepts. i find rocketlab's electron ditching batteries on it's way up a hilareous solution to the problem of electric fuel pumps.

[Lunar River]

On 3/21/2024 at 2:37 AM, Uttamattamakin said:

 

Just to check I asked Copilot to figure out how many Saturn V F1 engines would give the same thrust as superheav

What is your obsession with bringing AI into your rebuttals?

 

1 hour ago, Uttamattamakin said:

I hope Space X's plans pan out it'll be great if they do

..no, I don't think you do. You keep saying this throughout this thread, but I believe nothing would make you happier than to see spaceX fail.

 

You've already fallen into the "people who disagree with me are spaceX fans"

[wanderingfool2]

1 hour ago, Uttamattamakin said:

I don't get why it is controversial to point out that Space X has seen a lot of catastrophic failures for a system we are supposed to rely on. 

Because you are phrasing and acting as though it's a final product and showing a lack of basic understanding of how SpaceX is engineering the thing.

 

Again it's the whole concept of development.  SpaceX could spend an 5 - 6 years simulating, doing closed door testing, etc to get to the same point they are now...or they can just go out and test it can get enough information to accelerate their development cycle.

 

It's like the whole concept of Waterfall vs Agile development; back in the day the massive firms would insist that Waterfall was the only proper method, and that agile would introduce bugs/shows a lack of understanding.  Lots now in the industry focus more on agile development because it produces the results faster and gets to a finished product so much sooner at less cost.

 

1 hour ago, Uttamattamakin said:

I just don't like so many points of failure which when they fail they explode

1 hour ago, Uttamattamakin said:

See my point below more engines means more explode things that when they fail... fail HARD and fast.  Given the track record so far Starship has a 2/3 chance of BOOM. 

Ignorant statement showing that you don't know what you are talking about.  You want to say that it's because of lots of engines give PROOF of it by an actual rational argument how many engines failed it.  At the moment you just use an explosion as proof which isn't a proper rationalization of what is going on.

 

Here, let me break it down for you AGAIN:

 

IFT-1: Fire in engine bays, likely caused by hydraulic gimble system.  They flew knowing an explosion in the engine bay would take out neighboring engines though [they didn't want to retrofit their solution into it].  They flew the thing with 4 broken engines originally at liftoff.  Notice how those 4 engines didn't cause it to blow up on the pad and didn't abort the launch [although a 5th engine gone and it would have past the tolerance].

Eventually the fire got to the point it disabled the gimble system at which point termination was attempted.  So IFT-1 didn't have to do with more engines, it just had to do with fire prevention and using hydraulic fluid which becomes the fuel source.

 

IFT-2 booster: All engines fired perfectly, failed to properly relight because of fuel filter.  That would occur having single large engines as well.  So again not anything to do with lots of small engines.  More likely to do with the fact it's a 3600 ton mass where extreme forces are applied during a flip maneuver.

IFT-2 ship: Oxygen dump, which likely caused a fire in the hydraulic system again.  

 

 

They are exploding because they are trying to do things that really hasn't been done before and they are pushing their vehicles to the limits and at the same time flying hardware they know has faults but still flies it to gather more data about how it's flying [so they can make changes to future vehicles].

 

 

The chances of an engine exploding doesn't scale linearly with the number of engines when in relation to size.  Smaller engines are able to be produced more and tested/swapped out more when errors are present leading to a decreased chance of them exploding compared to a larger engine.  You get this benefit because they are able to manufacture like 360 engines in a year and test them all at extremes beyond what they will operate at and reject any that isn't performing right (or that fails).  If you can only make a few large engines though you don't have the luxury of testing them to the point where you might lose a few.  It is why Raptors will fail, but will fail in a less energetic fashion because they have already been pushed to an extreme that will not be met during flight.

 

Actually larger engines would mean you have larger pipes going to them, so when you shutdown the engine you get more of a liquid hammer than you would when you can shut-off smaller engines overtime.

 

Larger engines means more SPOF.  It's that simple.  If you want to keep claiming lots of engines = bad for Starship them actually try doing proper reasoning on WHY that amount of engines amounted to their failures...because again look above, notice how the reason for failures doesn't have to do with multiple engines.  In fact the IFT-2 ship and IFT-1 could likely be attributed directly to having a hydraulic controlled gimble. [IFT-3 had both systems electronic]

 

Again, like what I mentioning before, SpaceX is capable of over 10% of their engines during relight to fail and it will still be within it's capabilities.  If you use larger engines you knock the amount of engine failures down to 0% failures.

[manikyath]

2 hours ago, Uttamattamakin said:

Given the track record so far Starship has a 2/3 chance of BOOM. 

i missed this earlier.. but let's turn it on you...

 

Given the track record, SLS has a 100% chance of a 6 year delay.

[Uttamattamakin]

Hey last ever Delta Heavy launch EVER.  Take a look at the end of an era.  SCRUBBED and will try again tomorrow due to a technical fault during terminal countdown. 

 

It's the rocket version of. 

https://www.youtube.com/watch?v=MFYFt-jI184 --- Last of the V8 interceptors. 

[manikyath]

56 minutes ago, Uttamattamakin said:

Hey last ever Delta Heavy launch EVER.  Take a look at the end of an era.  SCRUBBED and will try again tomorrow due to a technical fault during terminal countdown. 

awh, so it's delayed, that's a shame.

[Uttamattamakin]

20 hours ago, manikyath said:

awh, so it's delayed, that's a shame.

Yeah I mean they don't want it to blow up so yeah. 

[manikyath]

2 hours ago, Uttamattamakin said:

Yeah I mean they don't want it to blow up so yeah. 

it's the last one they have, so i assume not.

[Uttamattamakin]

Hey everyone.  Been a while.  A falcon 9 is about to launch and watching a rocket as good and reliable as it go up is always cool.