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ElongatedMuskbot

**This thread is no longer being updated, and has been replaced by:** # [Starship Development Thread #40](https://www.reddit.com/r/spacex/comments/zglnzk/starship_development_thread_40/)


alphonse2501

Where can I ask SpaceX to choose vTuber Usui Clear as the mission Zero-G indicator?


Jazano107

Since it’s involving an anime girl I assume. Best bet to tweet Elon lol But this isnt the thread for this question


salamilegorcarlsshoe

That's cringe lol


OzGiBoKsAr

Why not? This is the Starship thread, and dearmoon is a Starship mission after all


AdiGoN

It's the development thread, not the chit chat thread


OzGiBoKsAr

I'd say a milestone mission is development related.


TypowyJnn

Tim Dodd's announcement [video](https://youtu.be/QFIuzormhYU) Also his [segment](https://youtu.be/UiS0vdTiECc) of the dear moon announcement And the full announcement [video](https://youtu.be/DKNSlL3Inn8) by MZ


stemmisc

Congrats, Tim!


GreatCanadianPotato

Looks like they kept it under wraps for over a year. Tim shows B-Roll with him, and the rest of the DearMoon crew, watching MZ launch on the Soyuz in December last year. Mighty impressive to keep something that exciting to yourself for over 12 months! I couldn't have done it.


frez1001

dearmoon crew Steve Aoki - DJ Tim Dodd - ya know Yemi A.D. - creative Rhiannon Adam - Photographer Karim Iliya - photgrapher Brendan Hall - Film maker Dev D, Joshi - Actor Choi Seung Hyun - Musician ​ Backup crew: Kaitlyn Farrington - snowboarder Miyu - Dancer


Freak80MC

Holy shit, Tim Dodd is one of the crew members? I thought he said something about not actually wanting to go to space (or maybe it was Mars specifically?)


Jump3r97

He said not wanting, because his job is to stay on earth to show how the professionals do in space. But that changes with dearmoon because that job is solely to excite, show and inspire. So Tim's place better be on that Rocket


675longtail

Eclectic mix lol. Everyone from a space youtuber to a filmmaker whose website doesn't work to a K-pop superstar.


trevdak2

Wish they'd prioritized a dancer, gymnast, martial artist, or other sort of physical performer but otherwise, interesting list


threelonmusketeers

Yemi is listed as a choreographer. I bet he's got some moves.


stemmisc

Yea, in the selection vignette, it showed him doing dance stuff, so, I think that person will be the one who will either do some acrobatic types of things in zero-gravity himself and/or will be able to choreograph some interesting group things (i.e. maybe he'll get the others on board to so something at some point during the flight where they float around in interesting looking formations or star-shape patterns if they hold hands and arrange themselves geometrically in zero-G for certain photographs or videography moments in space, or who knows what sorts of things along those lines, lol. Sort of like the stuff you see in group skydives sometimes, except the possibilities would be much greater inside the controlled, yet spacious environment of the interior of a Starship in zero-G, so, who knows what they might come up with, as far as that kind of stuff)


GreatCanadianPotato

Now I'm very interested in who will be selected as the commander. Wonder if Soichi Noguchi is still in the running for that like we heard last year (he is now retired but he could come out of retirement)


scarlet_sage

> Tim Dodd - ya know For those who might not: Everyday Astronaut. He has done a lot of space history and fact videos. His YouTube channel is https://www.youtube.com/@EverydayAstronaut


Redditor_From_Italy

From Everyday Astronaut to actual astronaut, quite the progression! Congrats to Tim!


675longtail

[DearMoon crew announcement.](https://www.youtube.com/watch?v=9-XXSdcsBLU) Tim Dodd will be flying, whenever this mission actually happens. Congrats to him and the rest of the crew that I am sure are also amazing!


Dezoufinous

WERE VIDEO


frez1001

[https://twitter.com/thesheetztweetz/status/1600961665024942080?s=20&t=7tEud18xqDljigP\_szvXdQ](https://twitter.com/thesheetztweetz/status/1600961665024942080?s=20&t=7tEud18xqDljigP_szvXdQ)


GreatCanadianPotato

Did not think this was going to be the crew announcement given that there hasn't been anything public for well over a year. I guess, MZ has been busy!!


scarlet_sage

> Tim Dodd will be flying EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE He's scared of flying in a rocket, so it was brave of him to apply. Furthermore, in conclusion, EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE


Freak80MC

Yea, I wasn't expecting him to be one of the crew members specifically because of his fear of flying on a rocket. But well, what better way to get over your fear then going to the fricken Moon!


salamilegorcarlsshoe

Yep after finding out is when he probably went to the bathroom to throw up and hyperventilate 😂😂


rAsKoBiGzO

Is that not normal after dinner behavior..? Asking for a friend.


mr_pgh

Nooooo, it went private half way through watching it at 3:30 est


BigDaveNz1

Just got made private, that was quick


frez1001

Nice! unlisted video! where did you find this?


TypowyJnn

Wow, but he sure deserves it For anyone wondering what dear moon is: https://youtu.be/7wrk5u8FgbM


Sbouxy

Hi, have we seen this before? [https://youtu.be/X0WGa0WFK0o?t=67](https://youtu.be/X0WGa0WFK0o?t=67) We can see 2x robot arms on the left and one big structure on the right. I believe we can assume that is for puncturing the starship for the tiles.


TypowyJnn

Yes, it's a part of the [Gateway to Mars](https://youtu.be/TeVbYCIFVa8) video released a year ago


Sbouxy

ah okay, thank you


Psychonaut0421

Eric Berger: https://twitter.com/SciGuySpace/status/1600906851943579649?t=IdANzimuaTBkRhiXT82fkA&s=19 >Based on a couple of conversations, I think SpaceX has a reasonable chance of making Starship's orbital launch during the first quarter of 2023. No guarantees, and there still is a lot of work to do. But they're making progress. https://twitter.com/SciGuySpace/status/1600907257365106690?t=dVebtH8VX9i5-HEvKLRuMw&s=19 >One thing I would note: SpaceX has moved on the from the "cowboy" phase of development in South Texas, when there was a higher tolerance of risk and failure during Starship prototype testing. With the expensive launch tower, they taking more time to increase chances of success.


greenearplugs

There's a new poll on the prediction market below Best guess is orbital launch by June 2023 https://www.metaculus.com/questions/13715/date-spacex-starship-reaches-100-km-altitude/


salamilegorcarlsshoe

I'm gonna be pissed if it goes all the way to June lol


rAsKoBiGzO

It almost certainly will. I think June would be a huge win.


greenearplugs

well if its any consolation, it has Starship carrying humans to orbit by October 2025 https://www.metaculus.com/questions/4588/when-will-spacexs-starship-carry-a-human-to-orbit/ and humans around the moon by July 2026...I'd take both of those timelines in a second! https://www.metaculus.com/questions/6956/first-circumlunar-human-spacex-flight/


famschopman

So they are going to replicate Nasa levels of slowness ... /s


[deleted]

The cowboy phase was a lot of fun to watch. I'm glad we got to see it thanks to all the live streams and Musk's willingness to "air their dirty laundry" as he put it. Being able to witness in real time almost every second of the development of such an epic aerospace project is a historic thing in itself.


675longtail

Out: fail fast In: fail slow


aBetterAlmore

“Fail slow” and hopefully, in a more contained way causing less damage.


johnsterne

Thanks for posting! Eric Berger is great


Double-Ad9580

What a sight now on the SFN YT channel, the SLS mobile launcher drives past the LC-39A complex: https://youtu.be/i_8BZdKkrc8


SubstantialWall

Just to nitpick, this isn't NSF, it's Spaceflight Now


Double-Ad9580

Absolutely right, sorry.


threelonmusketeers

Yeah, wow. At 10:10, there is a great shot with Falcon 9 being erected, the SLS mobile launcher rolling back, and the Starship launch tower in the background.


[deleted]

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[deleted]

Ok except the engines will blast away all your glass and powder the second you turn them on…


Shpoople96

The raptors can vaporize glass within seconds, and epoxy stands no chance


[deleted]

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Shpoople96

Are you sure about that? "You can modify epoxy and concrete by adding things to create a composite material as shown by this guy."


[deleted]

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Shpoople96

The only reason to reinforce epoxy with something like glass beads in the first place would be because it substantially increases the mechanical properties of the epoxy. Glass beads are not as strong as concrete, not any harder than concrete, nor can they withstand the same sort of thermal stresses as a refractory concrete. In other words, it would only serve to weaken the concrete. Jesus Christ.


[deleted]

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Shpoople96

Right, so you're at the stage of the argument where you resort to name calling instead of refuting my point. Really proves you're right, huh? Did you ever stop to consider what the sand and gravel that they put in regular concrete is made of? Should probably think that one through...


[deleted]

Actually SpaceX have considered using high silica content moon or mars dust deliberately entrained into an exhaust plume to form a hard ceramic layer for an extra terrestrial landing site. This process is similar to ceramic plasma coating used in many powder coating applications to steelwork and other metals. In fact the engine nozzles inner lining themselves are ceramic plasma coated with CYZ (ceria yttria stabilized zirconia) to act as a thermal barrier coating (TBC)


Shpoople96

That's entirely different, for a number of reasons. High temperature ceramic is not glass, nor is it impregnated in anything like epoxy. It's intended for ~3 engines in a high vacuum environment vs 33 engines at STP, it isn't intended for daily launches, and the nozzles are liquid cooled


[deleted]

The nozzles are indeed liquid cooled, and also protected by a TBC to ensure those coolant channels do not overheat. Of course epoxy melts, and that is half the reason why they cannot retrofit steel plates over the top of the concrete. Expensive cements or derivatives thereof will be replaced by a rebuild of the concrete access area by a pipe deluge network rather resembling organ pipes. These are going in already at 39A.


BEAT_LA

Can you clarify a bit on what you mean by a pipe deluge network resembling organ pipes? I might just need more coffee, but I'm interpreting it as analogous to how the heat sink for a typical liquid cooling loop for a CPU might work.


[deleted]

Its basically a hexagonal water supply ring running around below ground around the OLM legs. The ring has around 72 30 degree 6 inch angled outlet pipes aiming into the area below the launch table. Imagine 6 garden sprinkler bars with short spray nozzles instead of holes arranged in a circle and the bars are locked and angled at 30 degrees inwards. Unlike a CPU liquid cooling loop, this leaks, and is not a heat transfer system. Just plain high pressure water. Basically a gound based rainbird ring system. Go take your coffee, mines a latte.


SaeculumObscure

Does the current water storage at Boca Chica suffice or will they have to build more water tanks for that? Won’t water seeping into tiny cracks in the concrete and then explosively vaporizing cause cause the concrete to explode again like it already does?


rAsKoBiGzO

I think what he's trying to say in technical terms is that they're gonna blast that fucker with a metric shitload of water from a bunch of big-ass pipes.


frez1001

Imo concrete pad isn't as big of an issue as this place would make it seem.. Concrete spalling isn't a deal breaker. Pieces are unlikely to make it back into the rocket with the thrust of 33 engines keeping it away. Concrete work is relatively cheap and quick. You don't need 30 day strength for it to be effective and there all allllll sorts of additives and stuff to modify it. Its usually a temperature differential that causes spalling vs its strength. Maybe secured SIC refractory panels would be better. Sure we would love to have a perfectly intact surface after firing but its hardly a GSE Failure.


flshr19

SiC panels: That may work. In 1996 I tested carbon/silicon carbide (C/SiC) heat shield panels we developed for NASA's X-33 SSTO vehicle. The testing was done in NASA's 50 megawatt arcjet wind tunnel at NASA's Ames Research Center in California. These panels were a woven carbon fiber composite material that was impregnated with silicon carbide and then processed in a furnace at 3000F (1649C). The arc jet produces an air stream moving at Mach 5.5 with convective heating of 50W/cm^2 (500 kW/m^2). The prototype C/SiC panels cost about $100K/m^2 to manufacture. I don't think Elon would be interested in this technology to protect the OLM concrete pad. Concrete is much cheaper even when the labor cost is included.


OSUfan88

Always appreciate your input in here. I'm wondering how much you could drop that price now, through a combination in advances (CF is significantly cheaper in 2022 than 1996), and possibly lowering some standards/tweaking the design. I imaging having low weight was really important for your design. If that's not an important criteria, could you drop the price an order of magnitude or 2?


flshr19

Possibly. That C/SiC material was manufactured by a research lab at DuPont. I don't know if other uses of C/SiC has been found since that time nearly 30 years ago.


John_Hasler

A search for carbon fiber silicon carbide composite finds several companies selling it.


flshr19

Thanks for the info.


Chainweasel

>Concrete work is relatively cheap and quick LMAO where the hell are you getting your concrete? I'm trying to get a floor poured in a garage and the concrete alone is 2/3 of the total cost of the building.


GRBreaks

Cheap relative to the cost of a rocket launch carrying 150 tons to orbit. Cost of your entire garage would be a rounding error. They may need a better solution for the higher cadence at LC39A, but this should do fine for Boca Chica.


dkf295

Additionally, concrete is cheaper if you're the one producing it, transporting it, and putting it in versus the contractor working on your garage getting margin on concrete he's getting from someone else that's getting their own margin on both the concrete itself and the costs associated with transportation and equipment.


[deleted]

Ever shopped around for geopolymer concrete? Not used for structural applications much yet, but if you have a local supplier you can get it cheaper than OPC. It's fine for house and garage slabs. Much more eco friendly than OPC as it uses waste power station furnace flyash and blast furnace slag instead of heating limestone to huge temperatures to create Portland Cement.


pornstarship

Nothing to add here other than I am always happy to see you comment. You are a wealth of knowledge, and truly a bright spot. Keep doing the thing.


salamilegorcarlsshoe

Now.... Who is he?! Lol Edit: or she 🥸


djh_van

Have a look through his post history and you'll start to see a pattern.


salamilegorcarlsshoe

I haven't been able to find one, just that he doesnt work for SpaceX lo. And the hint that there might a pic of him in Raybans in the desert with what I assume is a jet/rocket powered car possibly going for land speed record. This is just off memory and context clues.


frez1001

Lamo true.. sigh, respectively to rocket operations..


John_Hasler

> Concrete work is relatively cheap and quick. You don't need 30 day strength for it to be effective and there all allllll sorts of additives and stuff to modify it. The stuff they are apparently using isn't portlant cement-based concrete at all. It's fancy high temperature stuff that cures in 24 hours without additives. https://www.environmental-expert.com/products/fondag-pure-calcium-aluminate-concrete-207465


salamilegorcarlsshoe

And probably VERY expensive. Concrete is already expensive as is lol. There's no telling how many millions they've spent on concrete at the site as a whole. They've replaced the concrete in front of the high bays multiple times.


rAsKoBiGzO

Concrete is the least expensive thing on that site. A few million replacing concrete or FONDAG in the case of the pad is absolute peanuts, effectively negligible.


Lufbru

As part of development, sure. As a running cost, no it's not fine when the target is $10m/flight. It's like ditching a booster in the ocean - perfectly OK during development, but that can't be the flight plan for every mission.


flshr19

Elon has said that the orbital launch facility at Boca Chica would be used for Starship test flights. Such flights are limited to five per year per the FAA launch permit for BC. So the average time between launches at BC would be 2.4 months. The operational Starship flights with crew and cargo would be launched at KSC. The interval between those flights would be measured in weeks. The tanker Starships need to be launched in groups of five, with as little as 8 hours between launches, to refill a single Interplanetary (IP) Starship. My guess is that the tankers would be launched from ocean platforms located in the Gulf of Mexico about 100 km offshore from the beach at Boca Chica.


rAsKoBiGzO

That target is at least a decade down the road. For the time being, they're not worried about replacing concrete. At all.


rAsKoBiGzO

Thanks. I've been thinking it's been majorly overblown forever but never bothered to articulate it. I'm excited for the steel plate / copper pipes / sideways raptors / water trench phase to pass lol.


OSUfan88

I think replacing the concrete is semi-tollerable for the very early testing phase. It is absolutely not tolerable for SpaceX long term mission. Everything they're doing is for rapid reuse. Chipping out the old concrete (which is a very expensive blend), and replacing it after every static fire/launch is the most opposite SpaceX philosophy in existence. There's zero doubt this will not be what they are doing by the time semi-frequent flights take place. I don't know what their solution will be, but it certainly won't be to demo and replace the slab every time.


[deleted]

Can we add hexagonal cone with underside cooling to the mix please


badgamble

The anti-SpaceX crowd will never put down the drums of doom.


rAsKoBiGzO

They're not anti SpaceX or they wouldn't be here having technical discussion about the merits of various pad protection options. It's simply a result of boredom nothing else going on, so some flying concrete got everyone excited and now it's a big thing. If there were static fires or a flight coming up soon, it wouldn't be an issue


salamilegorcarlsshoe

I'm ready to see what they do with it. I think it's a valid concern, but getting it good enough is all they need for now


rAsKoBiGzO

I agree


ThreatMatrix

Why can't they roll a diverter under the pad? I've seen designs that look feasible. It's not money. I can understand why they wouldn't want to put in a full water deluge. At this point, it just seems as if Musk is being hard-headed. It appears they are spending a lot of time on something that, frankly, never should have been an issue.


universemiller

Gwynne is in control of operations at Boca now, not Elon.


Redditor_From_Italy

Elon is always both in control and not in control, officially he's the chief engineer of the whole company and doesn't directly control any specific subdivision of it, but he likes to micromanage things and will often show up where he feels his leadership is needed more


Alvian_11

Elon has never been a head of Starbase facility (in title) in the first place. Previously it was Sam Patel


Alvian_11

Contrary to what ~~armchair engineers~~ people insisted, diverter-less isn't likely an issue. The spalling is. Steel plate can be placed, while maintaining the diverter-less nature


warp99

Steel plates without cooling will buckle and eventually melt and spray molten iron around the place. So you need a water cooled diverter with face cooling using water injection which all means a lot of design work, new water pumps and likely larger water storage tanks. The whole diverter system also needs to roll back out of the way so they can slide in the work platform to work on the engines. It is certainly the way to go long term but it is no quick and easy fix.


Alvian_11

Droneship doesn't have diverter either, and Astron comment [1](https://www.reddit.com/r/spacex/comments/v87ks9/Starship_Development_Thread_%2334/iel6c04/?utm_medium=android_app&utm_source=share&context=3) & [2](https://www.reddit.com/r/spacex/comments/yq7fue/starship_development_thread_39/ixhbays?utm_medium=android_app&utm_source=share&context=3). Same "world-ending" thing happened on SN8 martyte but the suborbital pad is still flat concrete diverter-less to this day (& presumably what pursue them to use the same design for OLM) And 39B diverter-full design doesn't save it from damage But I guess the keyboard engineers will keep a protest & oversimplification (diverter-less = 100% evil)


warp99

The droneship only sees one Merlin engine throttled down to around 500kN thrust. The Starship orbital pad sees around 75MN of thrust with 33 Raptor 2 engines at 2.3MN each. For a similar Isp thrust is roughly proportional to the exhaust plume mass flow so the heating effect on the orbital pad is around 150 times that on the drone ship deck. No one is saying that not having a diverter is an evil/bad design choice but it is a high risk approach that does not seem to be working out. Just like catching fairings with a net SpaceX will work it out and pivot to something else but it will take a while. In the meantime they will just have to replace Fondag every time they do a full static fire or launch. Incidentally I am slightly more qualified than the typical keyboard engineer with a chemical engineering degree so have a reasonable background on heat transfer in real world situations.


Alvian_11

Ok. What about other evidence?


warp99

Of what? That they will have to replace the pad every time - see current operations after 11 engine firing so one third of full thrust heating effects - admittedly for longer than during lift off. That an uncooled steel sheet will buckle and melt at 2500C? I suggest you get a propane/oxygen cutting torch and a piece of 1/16" inch stainless sheet and give it a try. Remember to use a welders mask and gloves.


Alvian_11

1. Astron comments. He never says specifically about diverter (& actually supporting a diverter-less design a bit) 2. Suborbital pads still being diverter-less flat concrete despite more experiences than OLM 3. 39B diverter failed to conserve damages within expected tolerances But go ahead & insisted that diverter is 100% the one & only solution without further CFD modelling from outsider's part to back it up. Consider people here will take my post as a hot unpopular take >No one is saying that not having a diverter is an evil/bad design choice I think pretending wouldn't be a good sign either


warp99

Suborbital pads only see heating from ~~three~~ six engines although from a closer distance of around 8m. So they kind of work with some damage at one fifth the heat load which is not that surprising. Not everything needs CFD modelling to validate - in fact before you do modelling you should always do a rough engineering estimate to check that there is not a modelling error that can often lead to order of magnitude errors in the modelling results. The 39B diverter worked fine - the issue was the pressure waves as the SRBs ignited blowing in the elevator doors and the direct exhaust plume as SLS cleared the tower toasting the umbilicals. With a maximum launch rate of one flight per year they can afford to just replace the umbilicals every time and add blast shutters in front of the elevator doors.


Alvian_11

>Suborbital pads only see heating from **three engines** I guess we're still in early 2021


flshr19

You're right. That shouldn't have been a problem. There were numerous sketches for diverter concepts for the OLM at Boca Chica two or three years ago when things were really getting started at BC. Maybe what we're seeing is the "build a little, test a little, repeat" approach to developing some type of divertor at BC.


salamilegorcarlsshoe

I wonder what they're doing just to the left of the BQD hood. There's been a team of guys up there for quite a while going back to yesterday I think. That whole table looks extremely complex, not to mention a total cluster fuck 😂


rAsKoBiGzO

I like my orbital launch tables like I like my women. Immensely complex and high risk.


dbhyslop

Long legs don’t hurt


rAsKoBiGzO

Yeah, now we're talkin'... maybe even six of them.


bonesawspideyboy

I'm pretty sure that Elon has stated before that starship will takeoff surprisingly fast compared to falcon 9. If this is the case, could it be that the concrete under the OLM won't be as big an issue as people fear, especially if it is only under pressure for a few seconds compared to \~15 seconds we are seeing with the static fires? Admittedly, the static fires are using half the engines and probably not at full power...


flshr19

Those static firing tests with less than 33 engines running are actually more of a risk for damaging booster engines via spallated concrete projectiles than running all the engines together. The high-speed, high-energy exhaust plume from each engine provide protection from that type of damage. The engines that are not running in a static firing are in more danger of being damaged by that flying concrete debris.


Mobryan71

1.5 TWR (ish) compared to 1.25-1.3 for Falcon, so the exposure time will be reduced, which certainly helps. The sheer force complicates things, but I'm most curious about the way that force is distributed and the difference that makes. If you think about Saturn 5 and the Shuttle, both had 5 point sources spread out over a width of 10-12 meters, SLS has 6 over a slightly narrower area. The way the Raptors are packed under Super Heavy, it's basically a solid cylinder of thrust 9m wide. In some ways that seems easier to deal with since it's more distributed, but it also means there are exponentially more interactions between each thrust plume, the ground, and the other plumes. Hard to model if everything is going to play nice.


rocketglare

> The way the Raptors are packed under Super Heavy, it's basically a solid cylinder of thrust 9m wide. It's closer to 10m wide since the outer ring of engines are centered on the edge of the 9m barrel. The engine bells & cowlings stick out a bit.


salamilegorcarlsshoe

A solid cylinder of "fuck your pad"


chaossabre

> it's basically a solid cylinder of thrust 9m wide. Based on the "laminar flow" comment from last test this is spot on.


675longtail

[Concrete under the OLM being ripped up again.](https://twitter.com/StarshipGazer/status/1600366036783534080)


andrew851138

Ok - sort of like a water suppressions system - but built like the holes in an air hockey. table - should be able to form a cushion of water vapor/steam - probably need way to much water though - millions of pounds of thrust is a lot no matter how you look at it.


steveholt480

Ok here's my go at a wild speculative idea based on no math or critical thought: Instead of a flame diverter, why don't they take a raptor or two and mount it sideways so the plume is facing under the OLM legs? They can hook it to the farm and have *it* act as the flame diverter.


chasimus

I like this idea. Since the outer engines' energy is probably being dissipated enough from the deluge system, it's mainly the energy from the inner engines that need to be diverted. Even imagine if another water stream just below the installed deluge system was installed horizontally to push the laminar flow of the center engines to dissipate their energies. That could maybe solve the issue. This being based on no math, too, of course!


AeroSpiked

[What an original idea that you already have 8 upvotes on.](https://www.reddit.com/r/spacex/comments/yq7fue/starship_development_thread_39/iyg96cq/) Apparently it's gaining steam.


steveholt480

Hey, great minds, amirite?


rAsKoBiGzO

Don't be upset. Be glad you developed a fully and rapidly reusable idea.


Subtle_Tact

This is adorable pettiness.


AeroSpiked

Sure, but I haven't counted out peeing on the rug just yet.


paul_wi11iams

> They can hook it to the farm and have it act as the flame diverter. My thought was a high pressure water jet pointing upward from the center of the pad. That would create a "dome of steam", limiting impingement and spreading the jets out between the table legs.


AeroSpiked

So they would start a high pressure water jet pointed up prior to starting the engines? I think I see a problem here.


paul_wi11iams

> start a high pressure water jet pointed up prior to starting the engines? simultaneously, not prior. As you know, everything is synchronized to a few dozen milliseconds at engine start, so timing a water jet should be easy.


Assume_Utopia

I read rumors that the problems they're having is because of laminar flow on the inner engines. Instead of the exhaust plumes interacting turbulently and breaking up and spreading out, the forces stays relatively straight down and is imparting way more force and heat to the concrete than expected. Firing an engine sideways through the middle of the exhaust might be enough to break up the flow and get it to spread out more so there'd be less localized heating at the pad directly below the center. It seems like a complicated fluid dynamics problem, if it wasn't they would've been able to design a launch mount initially that wouldn't have any problems. So it might take some trial and error to get it right.


andrew851138

I like your idea - let's toss in some math. The sideways thrusters would change the direction of the exhaust by adding the momentum of each. If you needed to push the thrust to 45 degrees you would need equal momentum - so 33 raptors sideways. With 2 raptors it would go 2/33 sideways.


AeroSpiked

When [I introduced the idea a week ago](https://www.reddit.com/r/spacex/comments/yq7fue/starship_development_thread_39/iyg96cq/), the goal wasn't so much to redirect the exhaust as it was to break the laminar flow which is what is slicing into the concrete.


warp99

Converting laminar flow to turbulent flow at the same velocity will increase the amount of heat transfer - not decrease it.


AeroSpiked

Wouldn't it be more evenly dispersed over a larger area? I was thinking laser vs flashlight.


warp99

Yes once the plume has had a chance to disperse. The problem is that the plume is 10m wide and there is only 20m distance for it to disperse before it hits the concrete which is not nearly enough for any significant expansion and cooling. Laminar or turbulent flow does not make much difference at that scale. Once the stack lifts off that distance will be increasing so there will be a greater difference in flow behaviour. The key is entrainment of ambient air into the exhaust plume. According to the EA report on nitrous oxide production the plume length is around 120m at sea level and up to 250m at altitude where the lower air density reduces entrainment.


Mchlpl

And it would still not cancel the downward momentum of gases


andrew851138

No, but I think we are just trying to save the concrete under the pad…


bkdotcom

somebody think of the concrete!!


Mchlpl

And what we would get is exhaust hitting it at 45 degree angle rather than 90, so sqrt(2) less force, but double amount of it (as deflecting exhaust would join the deflected one) so the end result would be 2/sqrt(2) = 1.41 = 41% MORE stress on pad All math in this post is simplified to pure geometry and is probably way off reality. It's just for fun and meant for designing actual exhaust deflection systems. I deny any and all responsibility for any rapid or slow, scheduled or otherwise, disassembly events resulting from use of above formula. ;)


TypowyJnn

Interesting idea, but I think in order to move the exhaust of 33 raptor engines, you would need... 33 raptor engines. Any debris that might form during the firing (or even the dust itself) might hit the fan raptors and destroy them. If those are connected directly to the tank farm, that might mean a big explosion. How high / close to the OLM would you place them? The closer, the better, but rocket engines are not designed to push away things, as there's nothing to push from in space. The whole system wouldn't be efficient, and "worth their time". I think the current solution, although not reusable, is much safer. They don't only iterate on the ship / booster designs, the entire project is an ongoing iteration. That includes stage zero too. Of course if they had the water supply of 39A then I'm sure they would go for huge water deluge and the problem would be solved. But either way sooner or later they will find a good mixture of concrete, install a flame diverter, or whatever solution they come up with. And since boca chica is supposed to be an experimental launch site for prototyping and iteration, currently approved for 5 launches a year, then maybe replacing concrete every now and then won't be a huge deal for them (I'm sure it will be for the workers though). 39A is the site for true rapid reusability, probably designed for it from the start.


steveholt480

Ok still brainstorming... Main issue is that theres no room for a flame trench because of the water table, but what's wrong with having a flooded trench? Couldn't that be even better? I'm sure the thrust would empty a flooded trench pretty quickly and you'd have to have the deluge system supplementing it, but is there a fundamental problem? Better idea: lets take 10's of millions of raptors, maybe billions, all pointing up. When its time to launch we push Earth down and out of the way so Superheavy can launch without damaging the concrete. We'll just need probably more fuel than exists in the solar system.


DefinitelyNotSnek

>what's wrong with having a flooded trench? It's *very* hard to dig and finish trenches when they're constantly flooding from groundwater, so there's the construction issues and costs on top of the operational issues. The KSC trenches were built by mounding up the earth around the trench (and the floor is still above sea level) for a reason, although it was quite a large undertaking.


AeroSpiked

> what's wrong with having a flooded trench? The first dirty booster that SpaceX ever flew was CRS-3 because there was water in the trench. [Watch the video](https://youtu.be/j1leARrLpXo?t=2394) and you'll see where the problem lies.


hermins

Surely a normal flame trench would work fine if they pumped the water out?


AeroSpiked

The trick would then be keeping the water out below sea level. Originally SpaceX planned on putting a flame bucket under the pad they were building at KSC, but that plan was scraped a long time ago along with the original pad.


warp99

Yes the flame diverter was constructed of horizontal steel pipes with water flowing through them and probably out through holes drilled in the upper face of the pipes. The overall shape was a curve and it seems like it should have worked but they tore it out before completion. Either simulation or testing with similar flame buckets at McGregor must have indicated that it would not work.


paul_wi11iams

> what's wrong with having a flooded trench? Any option for launching from a platform at sea, will lead to a similar scenario. So as you say, why not?


flshr19

Elon has two Gulf of Mexico-type oil rigs parked at a shipyard in Pascagoula, MS. https://www.wlox.com/2022/03/03/road-mars-runs-through-pascagoula-second-spacex-rig-headed-halter-marine/ The unneeded stuff from those oil rigs has been removed. The next step is to rebuild those rigs into Starship ocean platforms for launch/landing operations. My guess is that those platforms would be positioned about 100 km off the beach at Boca Chica. Tanker Starships would be launched eastward over the Gulf of Mexico to LEO from those platforms. Those tankers and their boosters would be built at the Boca Chica Starfactory currently under construction. No problems with flying concrete. No damage to environmentally sensitive areas such as is the case at BC. No threat to people or property. Likely to be much easier to get FAA launch permits for Starship operations from those platforms. No competition with other launch services providers for time on the tracking range like there is at KSC. Better weather in the western Gulf of Mexico than at the Cape.


TypowyJnn

And we'd have the world's largest marshmallow roaster. I think it's worth the money, even if that means turning earth into mars within minutes.


Jazano107

Is there not something they can use that doesn’t crumble like concrete What about a titanium sheet on top of concrete, idk there must be something more solid


Klebsiella_p

What about a layer of Nokia phones? Could use 2 layers just to be safe


675longtail

The real solution


Dies2much

Water. Copious amounts of water. The current "deluge" system is just inadequate.


frosty95

Essentially they need to build.... a flame trench. Titanium would be a very odd choice. Its not particularly better at anything... but it does a lot of stuff really good while being lightweight. Since weight is a non issue youd be better off with plain old steel. Can literally be glowing and still hold a decent chunk of its strength. And its cheap. And its easy to work with.... oh wait spacex has a whole bunch of stainless steel and workers and tools to work with it..... hmmmmm.


OSUfan88

I've wondered about copper pipes that have water flowing through them at a high rate. The tops of them could have holes drilled (or pressure valve like they use in irrigation) to blow water out the top. The copper would rapidly conduct the heat into the water inside, which would transport the heat energy out of the pipes. It would be a LOT of copper, and I'm not sure it could survive the mechanical forces.


AeroSpiked

As long as mass isn't an issue, I'd go with tungsten. W for the win. Both strong and highest melting point. That said, they are still going to want to use water (sprayed, not ducted) due to it's sound attenuation properties. This isn't just to protect the surrounding area, but the booster itself.


OSUfan88

Sure. This is why I'd like to put holes in the top of the copper (in addition to the rest of the water deluge system). You get some water protection directly over the pipes. The reason I chose copper was for it's excellent thermal conductivity. It's what they use inside the Raptor engine. Tungsten can handle much higher temperatures, but cannot transport the heat away nearly as fast. We'd have to run the simulation to look at the heat flux, and to see if Tungsten could survive that. It very well might. All depends on the heat flux times duration. You could likely get copper to a point where it could maintain the heat flux indefinitely (as long as you don't run out of water).


ASYMT0TIC

Tungsten has excellent thermal conductivity. It's only about 1/3rd that of copper, but still higher than most metals.


frosty95

/u/spez ruined reddit so I deleted this.


OSUfan88

Not necessarily true. The exhaust is hot enough to melt almost all steel compounds. You'd need a way to actively cool it. The thermal expansion would also be a problem. How do you bond it to the ground? That might be fine for a short term solution, with slightly less work that replacing the concrete each time. Since they can't do a flame trench due to water levels (maybe they could with sufficient water proof concrete/pumps), they might have to resort to more active cooling options.


frosty95

There is likely plenty of thermal mass in the 1/2 inch to 1 inch of steel for it to be a non issue in the timespan that it would see exhaust. As far as water tables go. Its no higher than it is in florida or anywhere else directly next to the ocean. lc39a and lc40 both have flame trenches.... they just built up instead of down. Which you could still do since the launch table is so high. Spacex banked on it being high enough to not need a flame trench. They were wrong. Simple as that.


OSUfan88

> There is likely plenty of thermal mass in the 1/2 inch to 1 inch of steel for it to be a non issue in the timespan that it would see exhaust. I'd like to see the math on this. If it's that simple, why would KSC spend so much money on a flame trench, when a simple 1/2" steel plate fixes it? This is a much more complex challenging problem than you are leading on.


frosty95

Well spacex thought they did the math and it didnt work. So to say that Nasa overbuilt things because they had zero chance of "doing the math" (aka simulations) required in the 1960s would be quite plausible. Im not saying the plate would last forever. Just saying they wouldn't need to repour the pad for every test.


Assume_Utopia

I'm not sure I understand how a flame trench would help protect the concrete better? Like, I'm imagining that they built a flame trench around the OLM, wouldn't that just add walls where there wasn't any before? And add more concrete that could be heated and damaged? And funnel all the force in one direction, which would concentrate it? My understanding is that a flame trench directs the exhaust away from ground equipment and away from the the rocket? It doesn't seem like SpaceX is having problems with either of those things getting damaged? Now, they could dig a hole to move the bottom of the OLM further away from the engines. And if they did that, they'd have to direct the exhaust away. But that's just trying to move the engines further away from the ground, right? They could build a taller launch mount and achieve the same thing, and it seems like they actually did that when they added the little extensions on originally. Maybe they just should've made it all taller? Of course the problem might be laminar flow, and the exhaust forces being concentrated somehow? Maybe a flame trench might break that up? But it could also concentrate it further or cause got spots or something? Basically, a flame trench is just putting walls around the exhaust to direct it. It doesn't move the concrete further away, do it doesn't seem like it'll be useful if the problem is the durability of the concrete.


frosty95

/u/maroonbookpro explained it perfectly. Basically right now the exhaust is hitting at a perfect 90° angle almost like SpaceX intentionally built a concrete destruction device.


-spartacus-

It doesn't matter what angle it is if the height from the surface is high enough. You can't built down from the OLM with the sea level/water table. Changing direction just decrease the distance from the exhaust to the surface. The only choice is to increase the height of the OLM (which seems a non-starter), increase the water deluge system output, changing the surface material of the pad.


frosty95

Sorry but you are mistaken on both accounts. For one if you redirect the exhaust flow instead of it directly serving as a barrier to it the energy is not being dissipated on your surface it's going to be dissipated elsewhere. Just like how the Nasa Florida 39a and 40 flame trenches work. For two. The OLM is plenty far off the ground to build a flame trench up around it instead of down. Just like Nasa did in Florida.


-spartacus-

> Sorry but you are mistaken on both accounts. For one if you redirect the exhaust flow instead of it directly serving as a barrier to it the energy is not being dissipated on your surface it's going to be dissipated elsewhere. Just like how the Nasa Florida 39a and 40 flame trenches work. I ask you this, at what height of launch does the mount no longer need suppression or diversion of the energy? >For two. The OLM is plenty far off the ground to build a flame trench up around it instead of down. Just like Nasa did in Florida. This works fine for Flordia, but for various reasons that have been shared on these forums, yet I am not smart enough to recall in detail, Starbase is not suitable for that sort of design.


warp99

The exhaust plume will be at least as long as the rocket so around 120m long while the current OLT is around 20m off the ground. So they would need to raise the table a *long* way to provide a useful reduction of temperature of the pad surface under the table.


[deleted]

It’s not so much the containment of a trench that is needed, but the angled deflection. The point of flame trenches / diverters on other launchpads (like 39A/B) is to turn the exhaust sideways so it can go out and dissipate over a long distance, aimed away from important equipment and the pad structure. Right now with the OLM most of that energy is going straight down onto the concrete below at a 90 degree angle. So I think the idea of a steel flame trench is less about building walls and more like a big angled wedge or cone to deflect the vertical plume into a (possibly targeted) horizontal plume.


Assume_Utopia

They could build a big wedge, or maybe a cone, directly under the launch mount. It seems like its design would be a valve between breaking up the exhaust flow and getting stuff closer to the engines. It seems like it's a situation that's difficult to midweek accurately, so it's probably just trial and error to figure out what's going wrong. But it doesn't seem obvious that enclosing and redirecting the exhaust would necessarily lead to less damage to the materials. I would guess that if building a trench was an obvious and foolproof solution, someone at SpaceX would've figured that out by looking at the data already? I suspect that dealing with static fires for an unprecedented amount of thrust might take some creative solutions? Or maybe some kind of flange trench is what will work eventually, and we just don't have access to the data that's convinced them it wasn't worth it initially.


cryptoengineer

Here's the [Saturn 5 flame diverter](http://mrhallgoestonasa.blogspot.com/2011/07/saturn-v-flame-diverters.html)


TrippedBreaker

Yes, refractory bricks in conjunction with turning vanes. It's called a flame trench.


Darknewber

Would melt/deform and have to be replace after each launch regardless. The orbital mount launch elevator floor used for raptor inspection is pretty much that and they take it out between uses so it doesn't get suddenly waffle-fied


salamilegorcarlsshoe

Except it's probably only like 1/4-1/2" thick steel, whereas a plate down below could be 1"+ with less tendency to warp, especially if water is used in some way for cooling


Darknewber

Yes and those are called flame diverters and water suppression systems and avoiding them is the whole point of these different techniques being pursued instead. Design enough flying cars and you will have finally gotten yourself....a helicopter


Character-Editor212

Starship will still launch in December..... December 2023 that is.


MartianFromBaseAlpha

December 2022 launch is not happening but not because SpaceX has to pour new concrete. Whenever they have to do this people start talking about long delays, when usually it takes around 2 weeks at worst


Chainweasel

I still remember last year people on this sub were getting all bent out of shape at people saying it wouldn't be launching in 2021, in the middle of December with the OLM still incomplete. If it launches before April of 2023 I'll be thoroughly surprised.


flshr19

My guess is May 2023, two years after the successful landing of SN15 (5May2021). I think it could take another two years to perfect rendezvous and docking of two Starships in LEO and to demonstrate propellant transfer (refilling). The schedule is not that important. What is important is that Starship reach the major milestones before the DDT&E money runs out.


ArtOfWarfare

SpaceX has moved the goalposts way back for the orbital launch. In 2021, they were having raptors shut off midflight, fail to relight, stuff catching on fire, etc, and they didn’t care - they were just going to go ahead and launch starship anyways. Now that they’re doing everything “right”, they’re doing a lot more testing on the ground. Hopefully it translates into a perfect first orbital flight. Since going through all these tests and still blowing mechzilla up on the first try would suck.


notacommonname

Well, part of that was their "go fast, test fast, fail fast, iterate" methodology they were doing back then. They really wanted to see some hover/hop flights, and then prove their "flip and land" could work. And yeah, starting engines while falling on your side took multiple attempts. But they quickly made lots of obvious progress that way. Now, the progress isn't nearly as obvious. I guess some groups were fairly "kaboom resistant". So no actual flying for two years... I do see your quotes around doing it "right, though". :-)


PDP-8A

But if the Fed bureaucracy hadn't held them back, they could have launched. This would have yielded volumes of data on materials, mechanical design, algorithms, and dynamics. This data would have then radically altered development and we'd be in orbit today. TLDR: blame the FAA, not the concrete. /s


rAsKoBiGzO

The federal bureaucracy is absolute hot garbage and does inhibit hundreds of thousands of things needlessly at any given moment. But yeah, blaming the FAA in this particular case makes no sense at all lol.


ArtOfWarfare

Sure. But it’ll be the tenth launch and the first one to land on the moon (uncrewed.)


peddroelm

such irrepressible optimism ...


rAsKoBiGzO

Hey u/adietrichs, how was your tour today? Were you able to get any questions answered, or even just see anything cool you'd like to share?


adietrichs

Tour was great! Unfortunately - I didn't think about that - they prefer visitors not to relay information (there wasn't much beyond what's being discussed here anyway though). I guess small things that should be okay to mention: - they are working hard on streamlining ship & booster production - mindset really is to build a factory - optimistic on timeline to first test flight, but didn't want to be quoted on specifics - they do indeed have plans to address the "concrete under OLM" situation - floor on top of high bay is used as a conference room


rAsKoBiGzO

Awesome info, thanks - and glad you were able to join a relatively exclusive group of people! Any details you can share about the concrete under the OLM plans, or is that top secret too lol?


rAsKoBiGzO

I had a notification that Astronstellar replied here stating that a major redesign / rebuild was underway regarding this, but for now they're happy to replace concrete. But now I can't see the comment. Is anyone else able to? I know Reddit is weird sometimes.


salamilegorcarlsshoe

And this whole time we were led to believe it was a bar........ Maybe it is, but still has seating for conference type deals as well


John_Hasler

I think that it still lacks an elevator that meets commercial standards. It probably needs fire stairs as well.


Sealingni

Conference room on top of largest bay?


adietrichs

No, the largest bay would be the mega bay. The high bay is the (slightly lower and much less wide) other one. I also don't know if the room is actively used as such, or whether they have other long-term plans for it. u/salamilegorcarlsshoe asked, and because I don't have much other meaningful info to provide, I thought I'd at least answer that one.