4 ms·

Show HN: Rocket Launch and Orbit Simulator

166 points by donutthejedi 9mo ago

I (17y/o) have been developing a rocket launch simulation that allows the user to explore what it's like launching a rocket from earth and putting it into orbit. This idea originally started as an educational simulation but as i've gone more down the rabbit hole the more i've wanted to make it realistic. The problem is that I've never had a formal orbital mechanics class or anything like that so I don't know what I'm missing, what I currently have implemented is: Variable gravity Variable Atmospheric drag (US Standard Atmosphere 1976) Multi-stage rockets Closed-loop guidance / pitch programs (works well within ranges 350km to 600km) Orbital prediction and thrusting options to change your orbit. The feedback I'm looking for is: UI improvements and possible future physics implementations that I can work on. Current code and physics can be found at: https://github.com/donutTheJedi/Rocket-Launch-Simulation https://github.com/donutTheJedi/Rocket-Launch-Simulation

tgig 9mo ago
Did you do all the math yourself?
- donutthejedi 9mo ago
  yup, derived most of the equations myself then double checked them before implementing them. That being said all of the positining is done through time steps and not so much equations
  - seabass-labrax 9mo ago
    Nice work! Had a "blast" playing it ;)
mstank 9mo ago
This is awesome, great work! There’s a huge audience for something like this based on the popularity of Kerbal Space Program. Biggest low-hanging fruit UI improvement would be mobile responsiveness. It was a bit challenging testing on my phone.
- donutthejedi 9mo ago
  Awesome, thanks alot, thats a great idea to work on
brookman64k 9mo ago
Why is it launching with a horizontal velocity? It initially moves to the right even when pointing up perfectly.
- donutthejedi 9mo ago
  Thats due to the rotation of the earth, for the purposes of the simulation the earth is rotating at 408 m/s (earths rotation at cape canaveral) so thats why It appears its going sideways
  - DetroitThrow 9mo ago
    But the rotational velocity of the rocket is going to be very similar to Earth's at the launch site. Eventually the rotational velocity between ground and the rocket will begin to noticeably differ, but the launch trajectory starting at 408 m/s would look terrifying if it were that way in real life.
    - donutthejedi 9mo ago
      Good point, I implemented that very early and hadn't really thought about it, let me look into the true solution, thanks
    - donutthejedi 9mo ago
      I found the problem, It appears that I had the earth staying stationary but gave its rotational velocity to the rocket, What i think needs to happen is I need to also be rotating the earth so the inertial frame stays the same. Thanks for bringing this up
    - sfblah 9mo ago
      I was able to fiddle with the settings so it launches in the air a bit and then hits the city. All by just going vertically. Pretty funny.
  - mholt 9mo ago
    Don't rockets also start with the same horizontal velocity though, since nothing canceled it out when it got off the launch pad? It would be like jumping, and finding yourself ~250-400 meters away from where you lept by the time you landed. That said, neat project, and way fun learning experience. Good job.
deleted 9mo ago
[deleted]
arnonejoe 9mo ago
Looks super awesome. Strong work! It showed the karman line at 98-99km. Maybe a tiny tweak needed.
fartfeatures 9mo ago
Much better than KSP2
headcanon 9mo ago
I'm sure that city just *loves* being downrange of the launch site :) JK, nicely done! lots of fun to watch.
- TeMPOraL 9mo ago
  Fortunately for it, that city is mounted on some antigrav sled and moves around to always stay ahead of the launch vehicle, safe from my totally not intentional attempts at crashing into it. Completely unrelated bug: pitch control can go down only to -5 degrees.
  - donutthejedi 9mo ago
    Took the anti grav sleds off, might be possible to crash into now idk
Teever 9mo ago
This is really neat. I've been toying with the idea of building something similiar but with a bunch of different space stuff, like a calculator for different rotating space station geometries, mars/lunar cycler orbits, or solar shade sizes/distances. It's been many years since I've done this kind of stuff in school and it's great to be able to refresh yourself on this stuff. The kind of UI you're using makes it really friendly and approachable, like a game.
caetris24 9mo ago
I think it's a good start, but the user experience and the color theme make the simulation cumbersome to absorb. Maybe you can do a theming exercise with an AI. The zoom feature is highly sensitive. It's not intuitive at first on what the user should do or take away from the simulation. The events feature is great, and essential. Looking forward to seeing the next iteration. Nice work.
MeetingsBrowser 9mo ago
This is really neat and pretty fun to play around with! How accurate are the simulations? I'm able to get orbit by turning 45 degrees as soon as I launch and then doing some minor burns at the height of the initial trajectory. I don't feel like this strategy would work in real life.
- GalaxyNova 9mo ago
  I think it would, given that there is no air resistance.
- donutthejedi 9mo ago
  Its fairly accurate as far as I can tell. Your right about the fact that It wouldnt work in real life due to the dynamic pressure your exerting on your rocket, using your method you get to about 150 kPa, Falcon 9 usually maxes out around 35 kPa so it would explode. Also it is a fairly fuel inneficent way of getting into orbit, but yes it is possible
- Intralexical 9mo ago
  Subtracting gravity losses, the largest effect of your 45 degree thrust vector would be sideways acceleration. Which is generally what you want, to get up to speed as quickly as possible, instead of wasting energy ascending vertically. We just don't do it on Earth because we need to get out of the atmosphere first for efficiency and structural reasons. But on the moon or another vacuum body, "diagonal kick followed by minor circularization burns at apogee" is pretty close to the optimal strategy. Even on Earth, it's similar to the trajectories proposed by SpinLaunch and other "space cannon" concepts.
zamadatix 9mo ago
How much AI was used vs manual lines?
- donutthejedi 9mo ago
  Around 90% AI for syntax, I did alot of debugging manually. For implementing new features I would design them and do the reasearch then have a AI write lines for me and verify the work
  - zamadatix 9mo ago
    It's a quick path to having something to play with but I'd encourage folks specifically wanting to learn something new or create something for a portfolio to try to have it be more the other way around: write 90% by hand, implement the features yourself, and have AI help you with the research and debugging (but not try to automatically write the code to fix the bugs). AI is really great at all of the things listed, but I guarantee if you were in an interview and someone asked you about this project your responses about how and why everything works would be 2x-3x stronger. If this was your 3rd time implementing an orbit simulator and you just wanted to get the bulk done quick so you could move on to work on new stuff then that's when having AI write the bulk & doing checking really works best as you're already an expert in what needs to be done rather than trying to learn about what needs to be done from someone/something else doing it for you. I say this as an orbital dynamics simulator in C++ having been one of my first big projects I put in a portfolio myself :). And I also like to use AI often, I'm not an AI hater in general, just I like to use in certain specific ways sometimes. Feedback on the UI side: It'd be cool if the stars used more random positions rather than sine/cosine looking patterns. There are lots of different approaches one could try (from simple random positions to very complex types of clustered randomness and brightness variation to realistic star maps). My suggestion would be to ask AI what types of approaches could be taken and try implementing whichever approach sounds the most fun!
    - shireham 9mo ago
      Curious what age bracket you’re in? I understand where you’re coming from, but I don’t think it will be the paradigm for the future. My own experience is that you actually learn a lot by having AI write piecemeal code and then do overall review.
MadnessASAP 9mo ago
What did you use for closed loop guidance? If you aren't aware of it NASA has a lovely paper called UPFG "Unified Powered Flight Guidance" [1] used for the space shuttle. This was implemented and made more universal for KSP (of course) by Przemysław "Noiredd" Dolata as PEGAS "Powered Explicit Guidance Ascent System" [2] If it's your thing you could try implementing it and getting a single continuous burn to final orbit. Awesome work BTW! [1] https://ntrs.nasa.gov/citations/19740004402 https://ntrs.nasa.gov/citations/19740004402 [2] https://github.com/Noiredd/PEGAS https://github.com/Noiredd/PEGAS Edit: I now see it's on your roadmap, so I guess it is your thing.
- lamontcg 9mo ago
  I've got another kos-PEG implementation here as well, along with a really extensive bibliography: https://github.com/lamont-granquist/KSP-KOS-PEG/blob/main/lib_peg.ks https://github.com/lamont-granquist/KSP-KOS-PEG/blob/main/li...
- donutthejedi 9mo ago
  For this model I kinda just made up my own system to play around with it, while it wasn't very effective it was pretty fun. That being said thanks a lot for the recommendations, I wasn't very aware of the options I had for it.
aardvarkdriver 9mo ago
Impresive work OP! Regarding other comments about AI use, I tend to agree but can maybe add some context. I finished my ME degree this fall and found dynamics to be the most enlightening course for me by far. The ability to build a reasonable approximation of real-world systems from a set of reference frames and ODEs is incredible, and I find that it has affected the way I see the world in a meaningful way. That said, a well-defined set of reference frames in particular are the "unsexy" backbone of modeling & sim work, and I acknowledge that the barrier for entry is somewhat high (cumbersome notation, some linear algebra/ODE prerequisites). It seems like you may already have run into a reference frame issue based on some of the other comments. I still think that this is worth learning unassisted by AI! If you're a textbook guy, Kasdin and Paley's Introduction to Engineering Dynamics is how I learned. If not, I'm sure many other online sources are useful. And once again, great work here. I have no doubt that this will be useful for your college search, especially with a well-understood dynamics foundation. Best of luck!

166 points by donutthejedi 9mo ago

tgig 9mo ago

Did you do all the math yourself?

donutthejedi 9mo ago
yup, derived most of the equations myself then double checked them before implementing them. That being said all of the positining is done through time steps and not so much equations
- seabass-labrax 9mo ago
  Nice work! Had a "blast" playing it ;)

mstank 9mo ago

This is awesome, great work! There’s a huge audience for something like this based on the popularity of Kerbal Space Program. Biggest low-hanging fruit UI improvement would be mobile responsiveness. It was a bit challenging testing on my phone.

donutthejedi 9mo ago
Awesome, thanks alot, thats a great idea to work on

brookman64k 9mo ago

Why is it launching with a horizontal velocity? It initially moves to the right even when pointing up perfectly.

donutthejedi 9mo ago
Thats due to the rotation of the earth, for the purposes of the simulation the earth is rotating at 408 m/s (earths rotation at cape canaveral) so thats why It appears its going sideways
- DetroitThrow 9mo ago
  But the rotational velocity of the rocket is going to be very similar to Earth's at the launch site. Eventually the rotational velocity between ground and the rocket will begin to noticeably differ, but the launch trajectory starting at 408 m/s would look terrifying if it were that way in real life.
  - donutthejedi 9mo ago
    Good point, I implemented that very early and hadn't really thought about it, let me look into the true solution, thanks
  - donutthejedi 9mo ago
    I found the problem, It appears that I had the earth staying stationary but gave its rotational velocity to the rocket, What i think needs to happen is I need to also be rotating the earth so the inertial frame stays the same. Thanks for bringing this up
  - sfblah 9mo ago
    I was able to fiddle with the settings so it launches in the air a bit and then hits the city. All by just going vertically. Pretty funny.
- mholt 9mo ago
  Don't rockets also start with the same horizontal velocity though, since nothing canceled it out when it got off the launch pad? It would be like jumping, and finding yourself ~250-400 meters away from where you lept by the time you landed. That said, neat project, and way fun learning experience. Good job.

deleted 9mo ago

[deleted]

arnonejoe 9mo ago

Looks super awesome. Strong work! It showed the karman line at 98-99km. Maybe a tiny tweak needed.

fartfeatures 9mo ago

Much better than KSP2

headcanon 9mo ago

I'm sure that city just *loves* being downrange of the launch site :) JK, nicely done! lots of fun to watch.

TeMPOraL 9mo ago
Fortunately for it, that city is mounted on some antigrav sled and moves around to always stay ahead of the launch vehicle, safe from my totally not intentional attempts at crashing into it. Completely unrelated bug: pitch control can go down only to -5 degrees.
- donutthejedi 9mo ago
  Took the anti grav sleds off, might be possible to crash into now idk

Teever 9mo ago

This is really neat. I've been toying with the idea of building something similiar but with a bunch of different space stuff, like a calculator for different rotating space station geometries, mars/lunar cycler orbits, or solar shade sizes/distances. It's been many years since I've done this kind of stuff in school and it's great to be able to refresh yourself on this stuff. The kind of UI you're using makes it really friendly and approachable, like a game.

caetris24 9mo ago

I think it's a good start, but the user experience and the color theme make the simulation cumbersome to absorb. Maybe you can do a theming exercise with an AI. The zoom feature is highly sensitive. It's not intuitive at first on what the user should do or take away from the simulation. The events feature is great, and essential. Looking forward to seeing the next iteration. Nice work.

MeetingsBrowser 9mo ago

This is really neat and pretty fun to play around with! How accurate are the simulations? I'm able to get orbit by turning 45 degrees as soon as I launch and then doing some minor burns at the height of the initial trajectory. I don't feel like this strategy would work in real life.

GalaxyNova 9mo ago
I think it would, given that there is no air resistance.
donutthejedi 9mo ago
Its fairly accurate as far as I can tell. Your right about the fact that It wouldnt work in real life due to the dynamic pressure your exerting on your rocket, using your method you get to about 150 kPa, Falcon 9 usually maxes out around 35 kPa so it would explode. Also it is a fairly fuel inneficent way of getting into orbit, but yes it is possible
Intralexical 9mo ago
Subtracting gravity losses, the largest effect of your 45 degree thrust vector would be sideways acceleration. Which is generally what you want, to get up to speed as quickly as possible, instead of wasting energy ascending vertically. We just don't do it on Earth because we need to get out of the atmosphere first for efficiency and structural reasons. But on the moon or another vacuum body, "diagonal kick followed by minor circularization burns at apogee" is pretty close to the optimal strategy. Even on Earth, it's similar to the trajectories proposed by SpinLaunch and other "space cannon" concepts.

zamadatix 9mo ago

How much AI was used vs manual lines?

donutthejedi 9mo ago
Around 90% AI for syntax, I did alot of debugging manually. For implementing new features I would design them and do the reasearch then have a AI write lines for me and verify the work
- zamadatix 9mo ago
  It's a quick path to having something to play with but I'd encourage folks specifically wanting to learn something new or create something for a portfolio to try to have it be more the other way around: write 90% by hand, implement the features yourself, and have AI help you with the research and debugging (but not try to automatically write the code to fix the bugs). AI is really great at all of the things listed, but I guarantee if you were in an interview and someone asked you about this project your responses about how and why everything works would be 2x-3x stronger. If this was your 3rd time implementing an orbit simulator and you just wanted to get the bulk done quick so you could move on to work on new stuff then that's when having AI write the bulk & doing checking really works best as you're already an expert in what needs to be done rather than trying to learn about what needs to be done from someone/something else doing it for you. I say this as an orbital dynamics simulator in C++ having been one of my first big projects I put in a portfolio myself :). And I also like to use AI often, I'm not an AI hater in general, just I like to use in certain specific ways sometimes. Feedback on the UI side: It'd be cool if the stars used more random positions rather than sine/cosine looking patterns. There are lots of different approaches one could try (from simple random positions to very complex types of clustered randomness and brightness variation to realistic star maps). My suggestion would be to ask AI what types of approaches could be taken and try implementing whichever approach sounds the most fun!
  - shireham 9mo ago
    Curious what age bracket you’re in? I understand where you’re coming from, but I don’t think it will be the paradigm for the future. My own experience is that you actually learn a lot by having AI write piecemeal code and then do overall review.

MadnessASAP 9mo ago

What did you use for closed loop guidance? If you aren't aware of it NASA has a lovely paper called UPFG "Unified Powered Flight Guidance" [1] used for the space shuttle. This was implemented and made more universal for KSP (of course) by Przemysław "Noiredd" Dolata as PEGAS "Powered Explicit Guidance Ascent System" [2] If it's your thing you could try implementing it and getting a single continuous burn to final orbit. Awesome work BTW! [1] https://ntrs.nasa.gov/citations/19740004402 https://ntrs.nasa.gov/citations/19740004402 [2] https://github.com/Noiredd/PEGAS https://github.com/Noiredd/PEGAS Edit: I now see it's on your roadmap, so I guess it is your thing.

lamontcg 9mo ago
I've got another kos-PEG implementation here as well, along with a really extensive bibliography: https://github.com/lamont-granquist/KSP-KOS-PEG/blob/main/lib_peg.ks https://github.com/lamont-granquist/KSP-KOS-PEG/blob/main/li...
donutthejedi 9mo ago
For this model I kinda just made up my own system to play around with it, while it wasn't very effective it was pretty fun. That being said thanks a lot for the recommendations, I wasn't very aware of the options I had for it.

aardvarkdriver 9mo ago

Impresive work OP! Regarding other comments about AI use, I tend to agree but can maybe add some context. I finished my ME degree this fall and found dynamics to be the most enlightening course for me by far. The ability to build a reasonable approximation of real-world systems from a set of reference frames and ODEs is incredible, and I find that it has affected the way I see the world in a meaningful way. That said, a well-defined set of reference frames in particular are the "unsexy" backbone of modeling & sim work, and I acknowledge that the barrier for entry is somewhat high (cumbersome notation, some linear algebra/ODE prerequisites). It seems like you may already have run into a reference frame issue based on some of the other comments. I still think that this is worth learning unassisted by AI! If you're a textbook guy, Kasdin and Paley's Introduction to Engineering Dynamics is how I learned. If not, I'm sure many other online sources are useful. And once again, great work here. I have no doubt that this will be useful for your college search, especially with a well-understood dynamics foundation. Best of luck!