Ultra Starship and Hypersonic Retropulsive Reentry
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- čas přidán 23. 02. 2024
- Let's look at hypersonic retropulsion for reentry! Could Starship go without heat tiles?
And what if we built a 200 meter tall 18 meter in diameter UltraStarship?
Something it looks like SpaceX is considering. How could we make it strong enough to survive the incredible weight of the propellant?
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Your channel finally popped up on my youtube page a while back I subscribed. As I am trapped in the body of a dyslexic currently I will receive a big fat F on the home work. However I really enjoy the channel I think it's the best and do learn from it.
Thank you Nemo! We are glad to have you! I do not love the math but I love knowing how to double check ideas :-)
1:46 IFT1 did not "fail to separate"; separation was never commanded at all because the stack never reached the altitude or velocity required for separation in the first place. FTS was triggered not because of separation failure, but because of loss of control (engine compartment fire on Booster 7 took out the hydraulics used for gimballing the center engines.)
That would make sense but wouldn't it have been a good way to check escape/abort? I was told they did order the separation but when it failed they went ahead and fired the FTS. Starship could have controlled itself and landed offshore where the booster would have been. Surely the thought of this.
@@terranspaceacademy this was put to Elon (via Twitter, by NSF people if I recall correctly), and he replied that in retrospect, that's what they should've tried to do - but at the time, it wasn't part of the literal flight program (as in, a contingency coded into the onboard flight control software.) And, neither was it included into the pre-filed flight plan, so that deliberately commanding the stack to fly outside of the prearranged flight envelope and test protocol per the launch license wouldn't have been kosher from a regulatory point of view.
Thanks for sharing your thoughts, ideas and videos. Addressed some ideas I’ve had in the past. My latest thought exercise was to ponder if Starship could be segmented into three of more parts using engines, fuel, and nose cone as needed with various cargo segments that could be interchangeable. Why spend time transferring fuel when you could simply undock the top and bottom from a dedicated fuel cargo segment and then reconnect the segments needed for reentry. The fuel cargo segments could then be docked together for storage and possibly repurposing after the fuel is used. Why carry vacuum engines to the surface of the moon if you can’t use them for landing or takeoff. Park them in lunar orbit for return trips and land a lunar cargo segment directly on the ground without needing extensive ladders or cranes to reach the surface. Perhaps load a automated tunnel boring machine on end in the bottom of the cargo segment to bore a deep shaft directly into the surface of the moon and lower the cargo segment into the shaft for protection afterwards.
A very smart man worked on that exact idea several years ago my friend and I thought it was brilliant. Sadly, without a LOT of funding, building Starships are just for the billionaires :-) But you are quite right. It is an excellent concept.
I agree 💯 with the Nose Cone separation concept .. Although Elon is Right about " No Part is the Best Part" redundancy in Personal Safety should be THE exception... We may find in a worst case scenario; that this could be a Useful advantage to keep in mind.
I think so too...
4:01 6:03 Booster will NOT use a reentry burn, unlike the Falcon 9. This is both because SuperHeavy stages (and therefore reenters) at lower velocity than Falcon 9, and also because SuperHeavy leverages its stainless steel construction and engine shielding to tolerate much higher heat loads. By eliminating the reentry burn with the SuperHeavy, SpaceX is able to further optimize for mass to orbit, as well as eliminating a whole subset of potential failure modes.
Thank you... Not having seen one survive that far yet I wasn't sure they had decided.
Excellent stuff bro
Much appreciated
good job
Thank you my friend!
Cool!
Thank you
Too technical for me but I gave you a like 🙂
Thank you Claude!
I was wondering about incorporating Stokes designs into starship too. But i if they went with such a radical redesign they would look at moving to hydrogen 4 the 2nd stage as well now that it’s looking leashed to manufacture that fuel on mars than from c02 & u need to extract water from the ice anyways. Turning the outer ring of 1st stage into a a giant continuous aero spike could be something SpaceX thinks is worth the effort. I think your tank redesign will add too much weight.
It does indeed add some mass but would that be necessary for the structural support of an 18m system?
@@terranspaceacademy Elon will throw mass at a problem to achieve safety / reliability, but if you look at what he is saying about just making hte rocket longer, I don't see him doubling the size or buildiugn a tank in side a tank like this. I do think it makes sense to increase the diameter of the 2nd stage so they can incorporate some of Stoike's tech, but I don't think Elin wants to spend time on that.
Has SpaceX told us if the Booster will fire its engines all the way down from 're-entry' to landing or will it be more like Falcon 9 with 're-entry' and landing burns?
Don't the StarShip Booster and Ship have larger LOX tanks than LNG/Methane? Mix is 3.6:1 LOX to Methane, isn't it?
Amazing homework problem! Can't wait for the answer...also would be a little terrified to watch such a massive rocket launch!
More like Falcon 9 I'm sure...
Great video as usual and again interesting ideas I agree a separating nose cone for safety to be a good idea but isn't there liquid oxygen tanks in the tip of the nose coat something done for centre of mass requirements?
wouldn't this make such separation extremely dangerous severing feed lines etc
Not sure I think the setting and retrieving homework to be a good idea as it might put some of your audience of not myself although I won't be doing homework maths not being my strong point something not helped by my being blind and syntax difficult in formula proving it a great memory Challenge
Cheers 0:03
Just an exercise for those who want to do the work. We'll cover it all before too long :-)
I'd be worried about thermal expansion if only the stainless steel was used as the heat absorber. Feels like a lot of warping and fatigue issues would present themselves rather quickly.
That's a good point... the question is how much heat would radiate to the ship?
Even if starship would enter base first, still would need a termal protection system (heatshild).
he was talking about using the engine's exhaust to move the shock away from the ship though, which keep the ship from reaching the temperatures where a TPS would be needed
@@demariultraastra864 I understood that part, but I don't think that could work for re-entering from orbital velocity(to much heat and dynamic pressure), also a thermal protection system purpose is not only for saving the vehicle from complete destruction by melting ,but also to recover a operational vehicle including less resistant to heat parts that are exposed, like electric actuators of the engines and propellant pipes gaskets, anyhow you can put at the base of starship a ceramic tiles heat shield that would be much smaller and lighter than current version , you only need to cover the exit of the nozzles with doors covered in tiles, after all the space shuttle had several of those doors in the heat shield , three for landing gear and two propellant pipes inlets and another two for attachment of the external tank.
@@theOrionsarmsThats a good point, I didn't think of that
I'm hoping that a powerful burn would get it past the plasma phase and then it can go horizontal, putting a lot less stress on the heat shields.
@@terranspaceacademy re-entering from orbit is a different things from what a falcon booster does, the energy is scaled with the square of velocities, so if you have 30 Mach instead of 10 you have 9th time more energy, and temperature increase with fourth power, actually the maximum 1650°C temperature of the space shuttle heatshild is pretty low because the hot plasma in front of any vehicle that come from LEO is closer to 3000°C , but a ceramic heatshild lose most of the heat by re-emission, this is the reason why is called radiative heatshild , if you want to blow something against that that hot plasma as a alternative method you need a lot of stuff, I don't know how much, but probably is close to half the mass of the vehicle. A somehow related method of regenerative cooling with liquefied methane was proposed for starship, but was abandoned after the calculations showed that the mass of cooling agent would be higher than a side mounted ceramic heatshild.
Woah woah woah my videos are giving me homework now?
Indeed! It is time to exercise those brain cells :-)
@@terranspaceacademy oh no! What am I to do! Gotcha! I normally just make up my own homework 😂 am I the weird one?
The Starship booster will be traveling much slower at MECO than the Falcon 9 first stage. I don't believe the Starship booster will be doing a reentry burn.
That's what I've heard. Steel is pretty tough too so you are probably right.
I would love to see a smart AI review all the technologies of all American space companies and spit out the best design for the task. That would be something to see.
Gotta invent one of those first
It would indeed... Evolutionary algorithms working on reentry etc.
Aren't there logistical problems preventing any increase in diameter? Something about the max you can put on a train or something like that?
That was the limit determining Falcon 9 sizing. Starship is already too large to transport by land; it'll be limited to barges for long-range transport and will be moved upright between manufacturing/test/launch facilities.
The biggest logistical challenge for increasing Starship diameter would be simply that all existing tooling, transport, and launch infrastructure would have to be accordingly resized.
Then there are structural and materials challenges, especially if increased diameter isn't accompanied by correspondingly decreased height: in that case, you'd be dealing with greater thrust (which would go as a square of diameter increase) leading to a need for much stronger thrust puck, correspondingly more engines, much more resilient launch site design, correspondingly larger exclusion and hazard zones, etc. Larger diameter also means more energetic propellant slosh, so extra mass for larger/heavier slosh baffles.
It would be better for a Starship competitor to start with an 18m diameter three stage all reusable system and work on that...
0:34 😂😂😂😂😂
Thanks :-)
Could you rotate the ship to spread out the heat over a larger surface?
That's the whole idea behind Starship's 'bellyflop' reentry (the Shuttle also did something similar, for similar reasons.)
But clearly, SpaceX's calculations showed that Starship could not survive its reentry with just naked stainless steel facing the hypersonic flow - which is why they deemed it necessary to add the thermal protection system on the Ship's windward side.
That's a good question but torquing that much thin steel mass under extreme conditions would be dicey :-)
We know that but is it possible? Just because they've chosen something doesn't make it right. No water deluge necessary? No hot staging to start with... etc.
The ignition sequence start of the Raptors is very tedious and critical, extremely sensitive to any fuel disturbances during low G transitions or staging. They tried to ignite the engines during IFT-1 but they didn’t operate… They should have tried to install simple ullage thrusters for staging first instead of adding 10 tons plus of hardware for hot staging, the less part the better?
Indeed but the hotstaging solves the escape abort issue...
The cowbells scattered around Boosters are tank vents. They can be used as ullage thrusters.
Apparently 400 tons of fuel still in the booster at separation.
For Starship?
Come on 2 hours!
Thanks for hanging in there!
Call it the MegaStar
Hyperion?
What about the issues with the temperature difference between the liquid oxygen and methane requiring lots of insulation? Sorry, I'm in the middle of switching night to day shift and won't be trying the homework.
methane and oxygen are actually liquid at nearly the same temperature, so the tanks themselves would almost certainly provide enough insulation to keep them both liquid, and the tanks on the current starship already have a common dome where both the methane and oxygen are in contact with no additional insulation.
They are massive heat sinks and with venting of pressure buildup in the upper tanks are effectively cooled by evaporation...
don't expand until you've done your homework.
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last warning.
1) I'm using half-cylinder for TPS mass (nosecone area reduction somewhat offset by extra flap area.)
2) not sure how the Raptor's exhaust velocity changes thru the atmospheric density profile, so used V.ex as avg of 3236.19 & 3726.53 (3481.36m/s)
-prop=mf * [E^(5800/~3481.36)-1] = mf * 4.291044
-for 50m SS, dry~120mT, prop=1200mT, 10%=120.0mT. mf=240mT, prop ~1030mT, tiles ~11mT
-for 64m SS, dry~132mT, prop=1755mT, 10%=175.5mT, mf=307.5mT, prop~1320mT, tiles~14mT
either way, tiles ~ 1% of prop mass for 5800m/s dV.
for 18m SS concentric tank 40% inner tank is 11.38m diameter.
Coming up... :-)
Why don't you seem to address deceleration?
As in the failure to reduce speed as expected?