Let's Talk Starship Reentry Aerodynamics for Flight #7 in January 2025

[@ismailnyeyusof3520]

This was great, Joe, I haven’t seen any of my other favourite KZbin content creators put together such useful information like this! Thank you!

[@JoeTegtmeyer]

@@ismailnyeyusof3520 glad you fund this helpful 🤗

[@clymerwright8591]

I work in aerospace engineering and had to google 3 terms, which led me to google six more terms and watch 4 more videos, thanks Joe!

[@JoeTegtmeyer]

@@clymerwright8591 👍

[@ellieinspace]

Very helpful video- thank you for making this type of content!!!! You are so knowledgeable

[@JoeTegtmeyer]

Thanks Ellie! I hope it helps a lot of people have a basic understanding of what the Starship faces during reentry and the incredible work being done by the SpaceX Team!

[@thrillchaser9492]

now you can copy him right

[@jamesmelandry3595]

I bet most people do not know how interesting this kind of explanation is until they have an articulate, knowledgeable individual such as yourself, lay it out for them, even if, like in my case they do not fully understand everything that is being reviewed and like one of your commenters did, finding it spurred him on to explore further anything that was a little to obscure for him at present, this is also my first time catching your channel, so glad I clicked on your teaser (Let's Talk Starship). Looking forward to seeing everything you have going forward, Elon is just the kind of patriotic billionaire this country needs, not only spending his wealth on things he loves but doing it where our country will continue to be the pioneers that has made us who we are as a nation. If only all the rest of his wealthy peris would follow suit.

[@chammockutube]

Engineering respect Joe. Thanks for a deeper dive, excellent descriptions, and a personal revisit to fluid dynamics classes decades ago and those great equations that Swiss mathematician/physicist gave us almost 300 years ago😳

[@martinbeverley9536]

Joe, the L H scale on the graph at 6:30 is logarithmic. The atmospheric density at lower altitudes does not increase in a linear fashion.

[@JoeTegtmeyer]

@@martinbeverley9536 yes you are right … I was attempting to show this in a simplified way and made an error … the log scale is a clue. My intent was to highlight the change in density versus altitude. Of course, you are correct.

[@WarrenLongCanada]

I agree with Martin. Most people don't pay enough attention to notice that it is a log scale, and hence the graph, although correct, is misleading.

[@run369]

thanks!

[@davidgrim9853]

Just discovered your channel! This is great stuff!

[@biovmr]

Wow, Joe, what a massive flashback to engineering school at the University of Missouri Rolla. In 1986 I bailed out on the aerospace engineering degree and Later finished up with IT systems analysis At the University of Maryland in Europe. That was a very impressive lay down of a very technical topic. Thanks again for all you do.

[@sidneydunavent]

Thank you for making the complex seem a little more simple. as a retired engineer, I enjoy this level of content.USA

[@DouglasJMark]

Great video Joe. This really helps me understand the flight characteristics of Starship.

[@JoeTegtmeyer]

Thanks Douglas!

[@PCMenten]

Joe, you made a good explanation of a complicated topic. Thank you.

[@JoeTegtmeyer]

Thanks ... it is tough trying to figure out how much technical stuff to add in .. it can get really complicated quickly!

[@allangraham970]

Fantastic you increasing your space coverage😀👍

[@JoeTegtmeyer]

Thanks!

[@garliccat8470]

I am interested in learning more about the effects of plasma on the vehicle in reentry, do you plan to make a video explaining this concept?

[@walterhiegel3020]

We are looking foreward to the next flight. I hope all are ready and the flight is not rushed. I hope there is no delays in all the apprvals. Go SpaceX!

[@JoeTegtmeyer]

@@walterhiegel3020 👍🚀🍀

[@huababua8203]

Great video! Love to listen to your deep dive! Keep it going man!

[@dougtruesdell9937]

Since the drag and lift equations are in the same form, the ratio between the lift and drag represents a constant during the descent. Also the density and velocity squared terms work in opposition - during descent, density increases in a logarithmic fashion, while velocity decreases in a somewhat linear fashion, but squared in effect. These two "constants" make it feasible to descend in control without extreme changes to the configuration of the airfoil.

[@daniellund8575]

Thanks Joe! Really appreciate the engineering content. Hope that you are able to occasionally include similar deep dives for your other videos as well when it piques your interest.

[@JoeTegtmeyer]

@@daniellund8575 🤗👍

[@larryschweitzer4904]

Excellent presentation, Thanks

[@kevinmccarthy8746]

FINELY, A Normal, person giving us the news, no BS.

[@WilliamDebnam-s6t]

This is a terrific "Down Home" and down-to-earth presentation. Excellent. Also impressive is your background collection of aerospace memorabilia. Great stuff!

[@JoeTegtmeyer]

Thank you William!

[@jimmirow]

New to your channel. Refreshing. Thank you

[@dphuntsman]

Good report, Joe. - Dave Huntsman

[@johnhjic2]

Hello Joe, What a super explanation, I know it is a simplified one but so well but together. Thank you.

[@JoeTegtmeyer]

Thanks John! It is surprisingly difficult taking a complex topic and making it both accurate and relatable to a wider audience. I'm glad this came out helpful!

[@Xoman08]

I don' t know. I would had thought that for flight 7 they would attempt catching both ships, Or at least have starship land on a platform drone. Great video, very informative. Much appreciated.

[@greggerypeccary]

Thank you, Joe. Now I understand why they moved the forward flaps up. Your atmosphere altitude/temperature etc. graph brought flashbacks of Microcal Origin...

[@YouT-DJ]

Awesome Joe- Complex and pushing boundaries as usual for Space X.

[@JoeTegtmeyer]

Thank you!

[@markeidem8436]

Excellent Joe! My bride and I will not be at the launch, as I picked up a nasty head cold and don't feel like travelling. Next time!

[@memrjohnno]

Great stuff mate though 6.5 minutes of blank at the end? Also some clipping which is often due to editing the narration late on without then regenerating the audio.

[@bishop1827]

Great summation and awesome graphics thanks 🎉🎉

[@JoeTegtmeyer]

Thanks ... I appreciate that and that you found it helpful!

[@carlmcc]

Thank you Joe! Very Helpful discussion! Fingers crossed for a successful flight!

[@guyg2005]

Thanks Joe for all the details. Felt like I was back in college. So when is 7 launching?

[@JoeTegtmeyer]

You are welcome ... I think Monday, 13 January is beginning to look more like the target date, but we shall see.

[@MaryBrewer-ot9qf]

Due to weather or what? I Hope it's sooner than that!

[@flintcoat2596]

I have a question! Is there a pressure drop behind the various shock waves on a super sonic vehicle, such as a F-104? I chose the F-104 because I know it has a long pointy nose. As the heating of re-entry is caused by the pressure, moving the pressure away from the heat shield, it would seem to me, would be advantageous.

[@dphuntsman]

That’s what a shock wave is, a sudden (to put it mildly) pressure drop, in extremus.

[@flintcoat2596]

@dphuntsman thanks, that's what I thought. Love your channel

[@oliviern4770]

Great explanation

[@francescodinardo3500]

Nice video, the diagrams and formulae makes the difference with tonns of other video that only repost and speculating on the upgrades. I have only a doubt on the stability, for what i remember the CG must stay in front of the CP to be stable, and also the center line distance is important for a for a vehicle flying at such high AoA.

[@datamatters8]

Very nice overview. Thanks.

[@JoeTegtmeyer]

@@datamatters8 🤗👍

[@slevinshafel9395]

12:15 Cp must be below the CG. otherwise it will flip back. Or in this case dont apply because we talking about landing and the gravity is going in the same direction(down).

[@slevinshafel9395]

thanks for goin on technical details. becuase big YT chanel just talk about how is moving the block frome one site to another(ehemmm NSF and Everyday astronaut and WAI)

[@JoeTegtmeyer]

I'm glad you found this helpful!

[@jimshreve83]

SUGGESTION: I don't know if this is on your end or mine, but the graphics are too close to the left border and cut off all the variables, but when I turn on the comments and the graphics are a little smaller I can read the left side. Thanks Joe! very informative. Love your Giga Texas videos keep up the great work. Have your best year ever!

[@joedonahue3746]

Great discussion

[@JoeTegtmeyer]

Thanks Joe!

[@creedsixteen891]

Thanks. Very informative.

[@JoeTegtmeyer]

@@creedsixteen891 you’re very welcome!

[@PETERVIKINGNAVY]

Great Joe. I have been looking for a simulation of the starship re-entry, Because I want to test an idea for not needing any heat shield. Spin the starship in re-entry along the long axis. This would double the heated area and thus half the heat buildup.

[@lachezarkrastev7123]

The elephant in the room - the temperature of the shield! I've performed multiple fluid dynamic reentry simulations with different AOA, speeds, altitude, pressures and even different more robust shield shapes. The conclusion - there is absolute no scenario in which Starship could be safe enough for even one reentry with humans on board and rapidly reusable. All designs and scenarios I've simulated melt/burn tiles and heat up the upper unprotected part of the ship up to 600 and even 700 degree Celsius. The boundary layer between the tiles and the plasma is well above 4000 kelvin ... so I gave up at that point.

[@micvvv]

Very good explanation - thanks Joe 💪

[@JoeTegtmeyer]

Thanks!

[@hungtuanbui9669]

Thanks Joe as always 👍💕

[@JoeTegtmeyer]

You are very welcome!

[@WarrenLacefield]

Thank you, Joe, for this clear discussion. Hopefully, someday (soon) there will be fuel depots in orbit (maybe refueled themselves from Moon-based production facilities). Imagine how nice re-entry might be if the StarShip in orbit (maybe after returning from the Moon or Mars) could be refueled. Then it could navigate a bit (for wherever it intends to land - e.g., similar to boost-back burns) before executing a solid entry burn to reduce that high velocity and making a graceful landing burn either for tower catching or leg-landing.

[@JoeTegtmeyer]

On-orbit refilling is the center of gravity of all future space missions, at least for the next 100 years or so and is critical to get established.

[@dphuntsman]

Propellant depots at ALL critical transportation junctions- in Earth orbit, Lagrange areas, etc. - are mandatory just for permanency of Cislunar development alone; much less for permanent space development beyond Cislunar. Keep in mind, tho, the first and primary reason for use of lunar resources is ON LUNA ITSELF; not to send out of Luna’s gravity well. It may, for example, make more sense to access near-Earth asteroidal material (energetically easier to get to/from, besides having more types of elements present) than lunar. - Dave Huntsman

[@WarrenLacefield]

@@dphuntsman I need to think about parts of that before I fully agree, Dave. Depots are needed and necessary for sure, every where we want to go. But I suspect, before and after habitats, people will want rocket fuel. Otherwise return is problematic. Building, living, and working, as well as exploring, at first will likely mostly be resourced from Earth. But fuel and later maybe certain materials will be principal exports.

[@johnalbinson4641]

Great update. Just one question ... will there be enough room in the top part to accomodate the unstable owner?

[@nowsc]

… how does it make sense that the underlying layer of the tiles is ablative? In the Mercury/Gemini/Apollo missions, the heat shield wore away, thus carrying heat with it. You’d think that an ablative layer ought to be on top, on the outside, no?

[@ZipZoomZip]

It sounds like it's a safety feature, so the ship is not lost simply because one tile, or a small section of tiles failed. These ships are designed for re-use, so this provides some safety headroom if tiles are damaged in undetectable ways on a previous flight.

[@JoeTegtmeyer]

@@nowsc no, this is a backup in case the primary heat shield tiles are lost or damaged and in localized areas. Totally different concept and goals from the obsolete Mercury/Gemini/Apollo missions.

[@keithhill7656]

I wonder how much payload Starship could manage to re-enter and land with? Thinking off returning payload from space and also a launch abort.

[@JB94083]

Well done.

[@KarlSchaeffer-es7nw]

Well done!

[@JoeTegtmeyer]

Thanks Karl!

[@john4flying]

Could the ship have heat shield tiles all over and 3 sets of fins at 120deg apart. Then during re-entry it could slowly roll to allow the heating to be spread over the whole ship and allow for cooling while in the lee-side.

[@peterhagen7258]

Joe; at T= 6:47, How is that density linear when it is plotted on a logarithmic scale?

[@jdp1991]

I've been watching your videos of GigaTexas since about your third video...Love the SpaceX info Joe! Keep it coming. Also, will you be attending Tim Dodd's Astro Awards later this month?

[@JoeTegtmeyer]

@@jdp1991 thanks! I’m not planning on being at the Astro Awards this year, unfortunately

[@stuartgraca]

I am sure there are lots of reasons to prevent it , but it almost sounds as though the fuel tanks should be above the cargo area, so that the nose is initially heavy when reentering ?

[@PC-nf3no]

So, with all that data of different temps and drag at different elevations and atmospheric pressures, then estimating reentry through Martian atmosphere becomes much easier to predict. Yes?

[@lourdessilva6442]

Maravilha adoro seus vídeos e agora falará da empresa dos foguetes isso não tem preço sem palavras es muito amor envolvido e nunca desistir no aguardo dos próximos sucesso

[@Gijs-t7p]

@6:44 That is NOT linear, since the scale on the left for atmospheric density is not linear but exponential, or logarithmic.

[@TimothyLipinski]

Great Video ! So can the Cargo Starship land with the HST ? If the mission can be done, then some Warranty work can be done on the Hubble mirror ! Where is Ellie in Space a strong supporter of your channel ? Timothy Lipinski

[@JoeTegtmeyer]

It would depend on the mass and payload arrangement, along with a corrected descent and landing profile, but I think it could.

[@charleslord2433]

Takes me back to my aeronautical engineering classes in college.

[@JoeTegtmeyer]

Me too!

[@mrsith1402]

Nice details

[@JoeTegtmeyer]

Thank you very much!!

[@gordonstewart5774]

Could the front flaps be removed?

[@sagecoach]

Great show and information. Also, the fall from altitude has gravity adding to the speed that drag is countering slowing down. The scale of the earth in the atmosphere layer chart is misleading. The earth is an order of magnitude bigger. The atmosphere is a very thin skin.

[@MaryBrewer-ot9qf]

Looks like Saturday may be the only good weather day for launch...

[@DataMetrics]

Small thing... Because the y-axis is logarithmic, one might call it "log-linear" instead of "linear". kzbin.info/www/bejne/iJTOn5dpp8uEn7c

[@JoeTegtmeyer]

Thanks ... ITs always a challenge to balance engineering & mathematical concepts with appeal to a wide audience, but you are correct.

[@budgetaudiophilelife-long5461]

🙋‍♂️THANKS JOE FOR EXPLAINING ROCKET SCIENCE IN TERMS 🧐 UNDERSTANDABLE FOR LAYPEOPLE 🚀🚀🚀

[@terrysmith8655]

Hey Joe, I know you flew re-fueling tankers in the military, and I saw your photo over your shoulder. If I might ask, do you have a Call-Sign, like Tesla Turbine, and if you do, would you mind sharing what it is? 😁

[@JoeTegtmeyer]

For me personally, I did not want a call sign, so I just went by Joe.

[@terrysmith8655]

Cool Joe, thanks for the candid answer, keep up the great videos

[@lourdessilva6442]

Eu sou do Brasil adoro esse tema que abordou e com legenda fica mas fácil compreensão pena que não temos no espaço x podia fazer uma live lá no espaço x mesmo não compreendo seu idioma eu iria prestigiar lo

[@lourdessilva6442]

Sensacional conhecimento nos liberta

[@Ulli4Ever99]

Habe nur die Hälfte verstanden, aber gut erklärt 😅

[@jimshreve83]

@Electobat You spelled Patreon wrong!

[@JoeTegtmeyer]

should it be TROLL?

[@sja45uk]

I don't understand why you say (12:50) that the Starship has no payload, when we know it is being launched with 10 simulated Starlinks. These will have the size and mass but not functionality of future Starlink 3 satellites. There will also be onboard the equipment needed to dispense them on the same suborbital trajectory. This guarantees that they don't join the existing large collection of orbital debris cluttering space.

[@JoeTegtmeyer]

The payloads are deployed before reentry

[@sja45uk]

@ True, but the payload dispenser clearly isn’t. I guess that what is considered payload is quite interesting, as it impacts payload to orbit calculations. All remaining fuel for landing is not payload, but offloaded or transfer demo fuel should be ?

[@OblivifrekTV]

Flight 7 just a week away, flight 7 just in a week! Meme

[@pfcrow]

I suspect the USA uses 80km instead of 100km so that we can have spy satellites dip below 100km without intruding on air rights. I think the 80km level is roughly the lowest possible stable point on a highly elliptical orbit, while 100km is the lowest stable point on a circular orbit. A quick search says 80km is where orbital mechanics is more dominant than aerodynamics. But I'm not an expert, so correct me if I'm wrong. Like any dividing line like this, it's rather arbitrary, and there will always be things right on the line.

[@TheEvilmooseofdoom]

Usually, when it comes to a circular orbit the Karman line tends to indicate the point where something can circle without propulsion. That is usually at 150km ish. That's why the line is 100 miles normally. :)

[@leeharrison2722]

Pitch control in reentry is of course critical, and the forces are large for a body like starship's (in contrast to roll and yaw). What these early reentries of starship showed was that the design of the V1 vehicles had been based on somewhat wrong estimates of the hypersonic lift distribution of the vehicle. Hypersonic aerodynamics is ... a bitch. It's computationally difficult, and wind-tunnel data in this regime is problematic because it's obviously impractical to get such data at anything except much smaller scale, and scaling effects aren't easy to understand or apply. We don't know how much direct hypersonic testing was done for the starship design -- possibly zero. it's expensive, slow, and due to scaling problems one often doesn't entirely trust the results anyway. SpaceX's willingness to "just try it" has clearly proven to be the efficient way to make progress, GIVEN that they can produce so quickly and incorporate changes ditto. I don't think that we need to go very far out on a limb to assume that SpaceX knew there were substantial uncertainties ... the first V1 starships had large flaps so that there would be enough control authority to deal with larger than expected pitch moments ("moment" to engineers is torque: force times lever-arm distance) -- fly it, including taking the risks that they were really far off (in which case lose the ship for sure) ... and find out. OK, now they have real flight test data, and V2 makes obvious (to engineers) changes ... all good. The heating and ship thermal protection is another issue. I think we can now be very optimistic that SpaceX will be able to get to no-repair-between-flights heat-shielding for starships that reenter from low-earth orbit (LEO), at low mass. (Right now testing isn't even at orbital reentry velocities, but not too far off.) But looking at SpaceX's goals, reentry from a Mars return transfer orbit is a tougher proposition, particularly with any substantial return payload. A Hoheman transfer orbit (lowest energy) produces a reentry speed of ≈ 11.5 km/s This isn't far from Lunar-return reentry, and obviously Apollo capsules did that, but they did it ablatively. Also the Apollo capsules had a lot less surface area per mass than than starship. Both of those made heat-shielding Apollo much easier. So .... we'll see. SpaceX hasn't made any presentations I am aware of where they stand relative to Mars-return reentry. Obviously returning rockets "could" use fuel (at a whopping price to have it) to reduce reentry velocities -- I doubt this appeals. Another option is to do one or more skip-braking passes -- basically making a very shallow reentry that "skips like a stone" back out, scrubbing off speed. The issue with these is that the "skip out" trajectory ends up being a rather large elliptical path of its own unless forces (and heating) in the skip are high. So this adds to total return time, particularly if more than one skip is needed. (Also a modest burn is required at apogee to get the wanted angle for the next reentry, but this is small and acceptable.)

[@jamesbruce1183]

Rocket Science!

[@JoeTegtmeyer]

That's my background and happy to share a little with everyone!

[@TeslaElonSpaceXFan]

❤❤

[@JoshKaufmanstuff]

So. . early in starships design Elon joked to his engineers to make it more "pointy" at the top . . . Ironic that this actually seems to have helped the aerodynamics of the vehicle coming from a parody video

[@batchint]

ethics for the future

[@cboy-ou2hr]

Is that bill nye the science guy?

[@JoeTegtmeyer]

@@cboy-ou2hr definitely not

[@lourdessilva6442]

Show adoro no detalhes

[@lourdessilva6442]

Adorei

[@kurknielsen]

Elon’s v2 & v3 announcement seemed to take spacex employees completely by surprise (see Elons town hall) , how do you explain SpaceX getting the math so wrong with starship payload capacity ? Lack of engineering expertise?

[@JoeTegtmeyer]

I think you have been listening to some pretty bad channels or news sources. You should subscribe to me and learn a little before drawing conclusions or making assertions that are not factual

[@kurknielsen]

@ cool, pls provide links to your videos where you discuss this.

[@lourdessilva6442]

Diante do cenário sombrios e de terror devemos ajudar na divulgação das empresas de nossa benção pois agora estará focado em salvar nossa amada e abençoada América das mãos desses terroristas e voltar a colocar lá em destaque como será fora cuidando zelando e protegendo nossos irmãos com as ações transformadoras extraordinárias e brilhantes junto de seu timaço e nosso guerreiro na torcida sempre a Vitória e luta só está começando nunca jamais ser surpreendido sempre surpreender uma eterna vigilância sempre a cada respirar só dependerá de cada um de nós Deus agindo sempre em sua gestão

[@TroyRubert]

Lfg!!!

[@JoeTegtmeyer]

Coming up this week (Mother Nature needs to cooperate a little)

[@stuartgraca]

The problem for the booster is possible engine damage caused by engine first reentry. There are a number of things that seem clumsy and makes me wonder about the total design concept being in need of major changes, although it appears they are just wanting to get to Falcon 9s level and not aim for much else. In my opinion there is no way this rocket is going to land on the moon or go to Mars, it as to be a new concept and a far more advanced one , which no doubt is ongoing.

[@JoeTegtmeyer]

What is your background in aeronautics and rocket design?

[@jimpiaz9537]

Hey tweet your audio or buy a better microphone.

[@dphuntsman]

I heard everything fine.

[@Phillip_Reese]

now you talk about other things that many talk about and my interest in you dissipated. Bring TESLA FACTORY with good pre developments. A spy job, I know.

[@Electobat]

Rather patronising.

[@dphuntsman]

??

[@GregoryJByrne]

"For what does it benefit man to gain the whole world but lose his soul?" Jesus Christ of God our father. AFT first.

[@hungtuanbui9669]

Thanks Joe as always 👍💕