Starship, Single stage to orbit. Is it possible?
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- Опубликовано: 4 июл 2024
- Can the spacex starship make it into space without the superheavy booster? What about single stage to orbitAn animated look at simulations which model real data and reasonable assumptions in comparison to the Ideal rocket equation.
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Thank you for all your insightful comments and at times differing opinions which is fine. May I just remind everyone to ensure comments are Polite, On topic, free of profanity and vulgarity and Respectful of others. Thank you very much!
A small nitpick. For SSTO, all nine engines would have to be sea level, or it either won' t take off (with 3) or do so really slowly (with 6) and unless we carry humans we don' t want to shut down engines cause it increases gravity loses.
The optimum is a 6 - 9 vacuum and sea level, thanks for the comment
add a mass acceleration system (assume 40m for the dry weight of the rocket at 2g) for the first 100m and fuel from the ground supply for 50% of the fuel used for 150m.
Thank you for your comment. Your plan as I understand it is to use a ground based mass driver to supply part of the required Delta V then allow the starship to complete the rest to orbit, I didn’t fully understand you data.
In a sense it replaces the Superheavy booster, to get the extra 2,000 to 3000m/s would require a significant length of electro magnetically levitating and propulsion track, it would also need to angle upwards as it is important to get out of the atmosphere quickly , I would be concerned about the aerodynamic stress on the rocket traveling so quick at effectively sea level. An interesting concept nonetheless.
I could actually see them using something like this for their military contracts that have been talked about for them delivering supplies quickly around the world.
When version 3 is out with about double the fuel this becomes an option for certain sub orbital trajectories to certain destinations
Cool. Solid video. What about a calc showing needed amount of propellant? Would a Starship 50% lager make it?
Yes can be done with some iteration, can put in needed delta V, from my simulations and data from the last 2 flights , I feel that the total required delta V using the rocket equation is 7800 + 2200 m/s for orbital velocity plus other losses, So if we assume the ship increases in mass to say 150 tons for increased size and tank size plus more engines for reasonable initial thrust to weight ratio, using my previous average ISP, then 2850 tons of propellant with a ship of 150 tons seems to just get to LEO
We have spent many decades and many billions of dollars studying SSTOs and so we know a lot about them.
And what we know is that they are no damned good. Period.
And both the rocket equation and the simulations say effectively the same thing. My point of making this video was to test out the theory and delve into a "what if"
In your simulations, did you include the mass of the heat shield and flaps? Because if we want it to only SSTO and not return to earth, we can ditch any parts that are only needed to return to earth, and thus save mass, effectively making it an expendable starship instead of reusable. Header tanks too?
I used the current ship and added a bit for additional raptors and associated plumbing, as 6 raptors will not lift the rocket, also I doubt using vacuum raptors at sea level is a good idea as the plume would be under expanded resulting in combustion and stability issues. So I guess the simulations could be rerun with say a dry mass of 100 tons
It will be interesting to see if SpaceX ever test the Starship's SSTO capabilities.
I see no reason to do so, but I would watch the footage! :D
Totally agreed, there is no need for SSTO otherwise why spend the time and money on 2 stages, but I like the “What if ……” scenarios
@@Sol24altthey could replace the falcon 9 for smaller missions.
Why didn't you do a simulation for a payload of extra fuel?
I will and will post it
So let’s set the dry mass at 120 tons and the fueled mass at 1200 + 120 +150 where 150 is the additional fuel and I will ignore the increase in mass for larger increased fuel and oxidizer tanks. The rocket equation gives 9300 m/s in which 1500 to 2000 m/s needs to be subtracted for gravity effects and drag, this leaves 6800 to 6300 m/s of effective delta V , my simulation for 160 km orbit is about 6,000m/s, either way it is still short of the 7,800 or m/s for LEO.
My interest is is how far can the booster alone get into space, without the Starship second stage mass ?
And then working back from there, what is the maximum payload that could reach geosynchronous orbit, if any?
Thank you for your question. The rocket equation suggest that with a fuelled mass of 3600 tons and dry mass of 200 tons and an average Isp of 340, as the engines would have to be sea level raptors , and at sea level Isp is suggested at 323s and would rise as it leaves the atmosphere. It gives a delta V of about 9600 m/s, from this we need to to subtract between 1500 to 2000 m/s for gravity losses, drag, gpe etc, this leaves a net delta V of about 8,100 to 7,600 m/s. aboit 7,800m/s is needed for LEO, so it suugest not much left, I try a coup of my simulations which suggested about 8000 m/s, which also suggests it could not get much beyond a 200 km orbit and nothing for GEO, of course all figures could be readjusted and perhaps a mix of sea level raptors and vacuum raptor could be used to increase average Isp and that the Booster dry mass could be reduced, but again this would increase the available delta V, but still probably still lacking for payload to geo. Anyway this is my take on it.
It can't. Period.
@@Sol24alt thanks
@@Sol24alt A better question, is how the Starship Lunar Lander… landing capability can be tested on Earth…
How high would they need to go, for simulation of lunar landing?
I not sure you could test the HLS here on earth, though I could be very wrong, principally because the earth has a thick atmosphere, so heating and resistance would come into play which it wouldn't on the moon, A short hop is possible to test certain features, but again the moons gravity well is so much smaller than the earths and the surface gravity is just 1/6.
This is a great exercise! However, I'm curious why you chose to use 9 engines. The Version 1 Starship uses 3 sea level and 3 vacuum Raptors. The Version 2 Starship has been stated to use 3 sea level and 6 vacuum engines but also is stretched to include more fuel. It would have been more interesting to run the numbers for the current Starship configuration, and also attempt a guess at the future Version 2 Starship.
Good question, with 6 engines, the Initial thrust to weight ratio would be at best 1 or less, hence it would not lift off unless substantially sub filled which would mean it would be far less capable
You underestimate the dry mass and other dead weight that starship have, for example only the cold and high pressure gasses needed to keep the structurall integrity during acceleration would have 30 tons probably.
Thank you for your reply, the actually dry mass of the starship is somewhat debatable, some sources including Elon suggest it as a low as 100 tons and some sources as low as 85 tons, I have used a more conservative 120 tons, as for how much pressurisation gas is needed, I cannot find actual details, note it is the goal to use autogenous pressurization which means methane (perhaps oxygen?) or combustants are used to pressurise the tanks. This makes it difficult to know exactly the mass needed, the sources I have seen suggest 300 kg Helium for Falcon 9, this would need to be scaled up, as for nitrogen, if they use cold gas thrusters in the final design, then some sources suggest about 600 kg of nitrogen. All this is hard to put an absolute figure on, so the final dry mass could be less than 120 tons or more as you say, though some of the gases would be expelled during launch, so it might be a bit more complex to model. Finally either way it cannot do SSTO.
@@Sol24alt it's nothing debatable about the type of gasses that current version of the starship use from pressurization, if you have some doubt I suggest to watch one hour interview that Musk give to Tim Dodd (everyday astronaut) from a month ago, and about the weight is a matter of pure science, one cubic meters of cold oxygen at sixth bar have around 2% of the weight of the liquid oxygen(so 23 kg/1cubic meter) even if it is with 50°C warmer than the liquefied one(that general rule of high density is applying for other gasses like methane and nitrogen, only exceptions are helium and hydrogen because of their low molecular masses) , obviously in the future they could switch back to helium, but if you speak about current starship you should include all the dead weight that needs to have, not only the gasses that are keeped in the tanks, but you need to include those that are vented overboard with the current rudimentary RCS system.
How about the super heavy booster? Could that do SSTO?
Having just run a simulation, then it appears yes, this assumes that there is no reentry, hence no heat shield or grid fins and the addition of a nose cone and some additional roll, pitch and yaw controls. Again I am just guessing at the dry mass (200 tons), but it suggests that it can just about make it, Obviously this is based on my simulation and there are still many guesstimates. Using the rocket equation, also it appears just about, but much is dependent on the dry mass and also realising that the engines would all be sea level raptors hence lower Isp (325) once above the atmosphere. than the Vacuum Raptors
No. No it can't.
in one of his many presentations of the concept, Elon Musk said that the starship alone would reach an orbital altitude but would not be capable of anything once there, so the presence of the super heavy booster becomes obligatory.
even with the booster the "Ship" will need refueling for the rest of the operations
Your comment is much line with both calculations, I was interested in the what if and testing and improving my simulation
SSTO is not very likely even with a dedicated version stretched for more fuel, you need a huge amount of fuel to get that speed.
Now ... the real question is ... can it get almost into orbit? Because thats what enables point to point flights. And even in those cases ... they could lighten up the heatshield as speeds shouldnt be as high. More in line with what Superheavy faces during re entry.
Still ... i would need to see hundreds of perfect landings before i trust it to land with that flip maneuver with me on board.
I agree, staging costs more but it is done because it makes the rocket more efficient by shedding mass that is no longer needed, but your point about single stage sub orbital is interesting. As for the heat shield though If you think about sub orbital, IFT4 went almost half way around the earth but the velocity still led to lots of heating at reentry, shorter flights would need a detailed velocity profile analysis to determine heating loads. However, I think you are on to something, but as you say, not going to happen soon
Look Falcon 9 is a success. Scaling that success upwards is a logarithmic challenge. 7 years and 1.5 billion into it and not even an orbit. They may not even be able to launch another mission because of the environmental devastation it creates. Use the falcon heavy and assemble your spaceship to mars while in orbit. It could be done already.
Falcon 9 is a huge success and Falcon Heavy massively underutilzed, see my video for 2x falcon heavy swapping with SLS and optimising Falcon Heavy. Your plan is similar to that of Verner Von Braun.
Starship is a much more ambitious project that the be fair has made great stride, of course slower than Elon predicted, but still has many. Challenges ahead. It is almost reinventing the rocket rather than a more linear advancement by other companies. The only point I would make is without the ambitious attitude Falcon 9 would not be the where it is now,
It can if you put a rocket underneath it ;-)
Very clever
Of course, anything is possible.
Take a look at Friendship 7.
That thing in Smithsonian, supposedly orbited the earth 3 times at the speed of 28,000 km/h in 1962.
And then it survived the reentry at 3,000 F - 7,000 F heat.
But the crude paint survived all that? 💩
..
It's a badly designed vanity project.
I suppose time will tell, it is certainly ambitious to say the least, but success is a possibility
Based on what? It’s obviously going to be used for starlink. They have a contract to launch a space station. The military is in talks about using it. They obviously have the moon contract.
It possible it could fail because of over ambition, but it isn’t just a vanity project.
NOT possible.
Because the Rocket Equation exists.
What? Starship? If it succeeds, it will change the space economy tremendously.
@@zbyszanna absolutely