Introducing Hatsunia's next-generation rocket: the M-III launch vehicle.
(Pictured is a prototype version using Velcro Rockets. Meshes and textures will most likely be different.)
The M-III is like a wider version of SpaceX's Falcon 9, except with 7 engines on the first stage, and all the propellants are methane/liquid oxygen (methalox). M-II had three different fuel types (kerosene, liquid hydrogen, and solid fuel), which would have had higher manufacturing and operating costs, but it could be justified as an optimization for performance. But now the Hatsunese space program will try to optimize for lower operating costs (although there is the expense of developing a new type of engine and fuel system), and will transition into a launch system with greater commonality.
Liquid hydrogen has the highest efficiency (specific impulse) for a chemical rocket engine, but its low density and thrust as well as higher dry mass fractions make less suitable for first stages. It is also known to gradually boil off in space. SpaceX also considered it to be too hard to handle. Liquid methane is the next best thing. Its specific impulse and density are in-between kerosene and liquid hydrogen, because an all-kerolox rocket would be a step backwards in performance for missions beyond low Earth orbit. Methane also has less problems with boil-off.
Unlike Falcon 9, the core diameter of which was limited by its need to be road-transportable, M-III will have an increased core diameter (about the same as Ariane 5 and 6, Delta IV and Vulcan, and the H3 rocket), which will be able to support wider fairings (and wider, heavier payloads).
Having 7 engines will help because I also intend to make this rocket capable of first-stage boost-back and landing using only the central engine (methalox is also good for reusable engines as it produces less soot/residue than a kerosene engine). This will only be possible with custom .dll programming, and this will be an attempt at doing that with no prior experience in programming Orbiter add-ons whatsoever.
So I would like to give much appreciation for BrianJ's hard work in making the code for his Falcon9R add-on, and many thanks for making it open-source so that people could use it as a reference. Especially the return-to-launch-site feature, as there are many people who believe that if SpaceX's approach to reusability succeeds, it will revolutionize spaceflight as we know it.
The plan is for the expendable single-core version to have an LEO payload capacity of about 19 tonnes so that it can have a margin for first-stage reusability (which is thought to be at least 30% with return to launch site). The M-III Heavy (three-core) will have about 60 tonnes of payload capacity in expendable mode (with crossfeed).
No real data references exist for methalox rocket stages yet (especially propellant mass fractions). But I found a thread on the NASASpaceflight forum that shows a hypothetical methalox version of Falcon 9. Both stages would have a propellant mass fraction of around 93.3-93.5%. I tried to message Dmitry Vorontsov, the one who conceived this hypothetical launcher, but he didn't tell me the exact methodology of how the dry masses of each stage were obtained (which I assume was too complex to be explained in a message, considering that he used to be a professional launch vehicle designer. Or he may have not had the time. I didn't want to bother him any further after that). I may or may not do some estimation analysis like this later on, but wouldn't material efficiencies for structures and tanks have gotten better since the days of Saturn V (especially with SpaceX)? So I'll just use the best (and only?) estimate for propellant mass fraction, which would be ~93.4%.
There was another person on the NASASpaceflight forum (Hyperion) who thought of an all-methalox launcher that was called "Neptune". M-III would be like the single-core and heavy (3-core) versions of that, but it won't have any more cores because multiple boosters are harder to recover. If I ever make a M-IV (and that will be the last designation because the next one will only cause inter-universal confusion), it will be something like SpaceX's currently vague plan for a fully reusable single-core super-heavy methalox rocket known only as the BFR (except somewhat smaller).
(Space Station Mirai is on hold for now, due to me forgetting to transfer some important files before coming back to college from winter break. The only things I have to do are the rest of the mission scenarios and the documentation. And I really wanted to get started on this.)
(Also, I've decided that the M officially stands for Mikubishi, which is the primary contractor for this launch vehicle series. Remember, it is an "M rocket," not a "Mu rocket.")
(Pictured is a prototype version using Velcro Rockets. Meshes and textures will most likely be different.)
The M-III is like a wider version of SpaceX's Falcon 9, except with 7 engines on the first stage, and all the propellants are methane/liquid oxygen (methalox). M-II had three different fuel types (kerosene, liquid hydrogen, and solid fuel), which would have had higher manufacturing and operating costs, but it could be justified as an optimization for performance. But now the Hatsunese space program will try to optimize for lower operating costs (although there is the expense of developing a new type of engine and fuel system), and will transition into a launch system with greater commonality.
Liquid hydrogen has the highest efficiency (specific impulse) for a chemical rocket engine, but its low density and thrust as well as higher dry mass fractions make less suitable for first stages. It is also known to gradually boil off in space. SpaceX also considered it to be too hard to handle. Liquid methane is the next best thing. Its specific impulse and density are in-between kerosene and liquid hydrogen, because an all-kerolox rocket would be a step backwards in performance for missions beyond low Earth orbit. Methane also has less problems with boil-off.
Unlike Falcon 9, the core diameter of which was limited by its need to be road-transportable, M-III will have an increased core diameter (about the same as Ariane 5 and 6, Delta IV and Vulcan, and the H3 rocket), which will be able to support wider fairings (and wider, heavier payloads).
Having 7 engines will help because I also intend to make this rocket capable of first-stage boost-back and landing using only the central engine (methalox is also good for reusable engines as it produces less soot/residue than a kerosene engine). This will only be possible with custom .dll programming, and this will be an attempt at doing that with no prior experience in programming Orbiter add-ons whatsoever.
So I would like to give much appreciation for BrianJ's hard work in making the code for his Falcon9R add-on, and many thanks for making it open-source so that people could use it as a reference. Especially the return-to-launch-site feature, as there are many people who believe that if SpaceX's approach to reusability succeeds, it will revolutionize spaceflight as we know it.
The plan is for the expendable single-core version to have an LEO payload capacity of about 19 tonnes so that it can have a margin for first-stage reusability (which is thought to be at least 30% with return to launch site). The M-III Heavy (three-core) will have about 60 tonnes of payload capacity in expendable mode (with crossfeed).
No real data references exist for methalox rocket stages yet (especially propellant mass fractions). But I found a thread on the NASASpaceflight forum that shows a hypothetical methalox version of Falcon 9. Both stages would have a propellant mass fraction of around 93.3-93.5%. I tried to message Dmitry Vorontsov, the one who conceived this hypothetical launcher, but he didn't tell me the exact methodology of how the dry masses of each stage were obtained (which I assume was too complex to be explained in a message, considering that he used to be a professional launch vehicle designer. Or he may have not had the time. I didn't want to bother him any further after that). I may or may not do some estimation analysis like this later on, but wouldn't material efficiencies for structures and tanks have gotten better since the days of Saturn V (especially with SpaceX)? So I'll just use the best (and only?) estimate for propellant mass fraction, which would be ~93.4%.
There was another person on the NASASpaceflight forum (Hyperion) who thought of an all-methalox launcher that was called "Neptune". M-III would be like the single-core and heavy (3-core) versions of that, but it won't have any more cores because multiple boosters are harder to recover. If I ever make a M-IV (and that will be the last designation because the next one will only cause inter-universal confusion), it will be something like SpaceX's currently vague plan for a fully reusable single-core super-heavy methalox rocket known only as the BFR (except somewhat smaller).
(Space Station Mirai is on hold for now, due to me forgetting to transfer some important files before coming back to college from winter break. The only things I have to do are the rest of the mission scenarios and the documentation. And I really wanted to get started on this.)
(Also, I've decided that the M officially stands for Mikubishi, which is the primary contractor for this launch vehicle series. Remember, it is an "M rocket," not a "Mu rocket.")
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