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We used OpenRocket for designing our rocket for UK youth rocketry competition UKROC[1].
It is great for getting a 'spherical cow in a vaccuum' idea of likely altitude with different motors, centre of pressure, center of mass etc. But it obviously doesn't take account of detailed aerodynamics etc and we found the maximum altitude estimates were about 15% too high. But it was still very useful.
[1] UKROC is an amazing competition for UK school kids. And there are equivalent competitions in the US, France and Japan, with an International competition for the 4 country winners. If you know any kids interested in engineering I recommend you look into it.
> we found the maximum altitude estimates were about 15% too high.
this often happens when the wrong rocket finish is selected. Everyone chooses a polished finish when in actuality they've just sprayed the thing with paint.
Skin drag is real.
I can't find the French competition, ironic given that the front page of ukroc is full of French gov officials... Could you share the name if you have it?
Heh, UK tinkerer here :)
How hard is it to get started for amateurs? Are rules/regulations problematic?
This application gets used a lot in the High Power Rocketry hobby. Most of the parts/manufactures are included as well as motor manufactures. The simulations are very good and accurate, I would sim my larger builds at the location where i was launching to get an idea of altitude and it was always pretty close ( within 5-10% i'd say ).
I use to have a website where you could upload an openrocket file and get back 2d drawings for your fins that could then be sent to my lasercutting service. The idea was design the rocket in openrocket, send me the file, and get back the wooden pieces you need cut per the design. Similar to sendcutsend but for the rocketry hobby.
Really cool seeing it show up on HN.
Software developers: I am begging you to put representative screenshots on the home page. This has become a real widespread problem.
I know you want to tell us all about the amazing (sincerely!) stuff under the hood, but to users, the interface is the product.
Thanks for the suggestion, I've added it to our home page.
I also like it when there's a short video that shows how the thing works and what it can do.
I can't believe how common this is now, if you dont have screenshots AND a video you are shooting yourself in the foot.
If anyone is curious of what I expect (in page order top to bottom)
Screenshot of complete product ui with description (showing complete UI)
Button to the download/buy product.
Header/tagline description of feature below:
Screenshot of individual parts of the UI (These are more often then not videos these days/gifs). Description of these screenshots
Buttons to expand to another page to learn more.
Bluntly, Just copy what other companies are doing. They are doing it because it works.
Example
Yes!!
Sadly they don't teach Show Don't Tell in the lectures
This is pretty cool. I remember having fun simulating my rockets using the BASIC programs from G. Harry Stine's "Handbook of Model Rocketry" when I was a kid. This looks like a way to recreate some of that fun.
Tangentially related is NASA's open source GMAT[0] software which is more focused for calculating orbital transfers and the like. It's pretty fun to play around in.
Well THAT's cool. I was just talking about getting back into model rocketry... I'm not sure my 6yo daughter will like it as much as I did/do but I want to get back into it and launch a few and see if she's into it. Timing here is great as I need to start looking at starting from scratch with kits etc.
I bought my son a Estes kit about 10 years ago. He's now at University studying aerospace engineering as a direct result. So you never know!
I read the name and the first logical thought that came to mind was that of a platform to have AI agents iterating on rockets design. How doomed am I?
Just reading the name I wouldn't have been surprised if it had nothing to do with rockets whatsoever - I was half expecting it to be some kind of "agentic platform to accelerate your product development" etc.
I think I need to go for a walk.
Generative AI iterating on design is being done with satellites in production already (and given that there's limited scope for real world testing so you're solving complex optimization problems against a set of models, actually represents one of the better use cases for generative design). Don't think the foundation models and physics based constraints solvers involved look much like LLM "agents", mind you..
OpenRocket has a little optimizer built in but of course it neglects structural integrity which it knows nothing of…
Why would you put that evil thought into other people's heads? Now someone might do that
I figured it was a typical no-info HN title; I was happy to discover it actually conveyed some meaning.
I wonder how crazy the scale here can get. How far can I go? The bps.space guy is heading into space. Can the community hit the moon? Literally.
Amateurs have reached the karman line, orbit is still pretty much out of reach. The people who get close to the karman line use two stage passive stabilized airframes and solid fuel motors. The airframes are basically works of art and it takes a lot of luck because of passive stabilization and Mach 3+ speeds. Many pictures of these rockets have their paint and leading fin edges burned off when they're recovered. Propellent is expensive and an attempt at > 100k feet is about $5-6k an attempt in propellent alone.
This guy is widely respected in the hobby and this flight made it to 293k feet https://www.youtube.com/watch?v=gmv7G6Rf5WE
Check out the liquid bi-prop engines the halfcat guys have, apparently they were just certified by the HPR hobby governing organization Tripoli which means they can be insured at sponsored launches. With a liquid fueled engine you can do thrust vectoring (nozzle gymbaling) easier than solid fuel motors so active stabilization is more feasible. If you have active stabilization then all you need is thrust to weight > 1, enough fuel, and you'll eventually get to whatever altitude you want. Orbit means orbital velocity and that's just a whole other ball game.
Space Concordia, a Canadian university space-oriented student group, which is sort of amateur-level given that it’s driven by students and donations, attempted to reach space not that long ago with a liquid fueled single staged rocket. Here is a video of the launch https://www.youtube.com/live/610YciEs8qg?t=4594&is=aAWo8Y7vi...
Might be worth checking out the "Copenhagen Suborbitals" group (they have a YouTube channel) and see if they're still active! It's been years but I think I recall they were trying to build something capable of getting a person into space (not sure if orbit was a goal).
"Space" is 100km. The moon at its closest is about 350,000km.
So the jump from the former to the latter is... significant.
Amateur rocketry achieving orbit would be significant. Reaching the moon would be substantially more difficult.
There is also the rocketpy framework. https://docs.rocketpy.org/en/latest/index.html
Essentially it can do the same thing as openrocket, but in python. You can even go as far as to simulate liquid fueled rockets during flight, modeling for example how the depleting tank influences the center of mass. My student rocketry team used this for the flight simulation of our Ethanol/Liquid Oxygen rocket which flew to over 5km
>My student rocketry team used this for the flight simulation of our Ethanol/Liquid Oxygen rocket which flew to over 5km
Cool. Is there more information on their rocket or a video?
I would recommend checking out your local laws on export of software with military applications. I believe this would be illegal to release in my country (whether that's the right thing is worth discussing, but protect yourself first).
Looks like a pretty mature project though so I suppose it must be on solid ground.
It might also run the risk of breaking IMPORT laws in your respective countries, worth being sure of because that is not a realm of law you want to be messing with.
Our university rocket team uses openrocket extensively for doing fast design iterations early in the design phase. We have also used Rasaero II which is meant to be more rigorous above transonic speeds. We have an Ansys CFD too but that requires significantly more time to set up.
We still use openrocket on launch days to do pre launch sims, but we override some of the parameters based on the more rigorous simulations.
Oh i've been looking for a project for my 11 year old... he's a very project oriented learner, which schools don't seem to do anymore.
What country are you in?
Im guessing that all the sudden interest in rocketry and drones is related to the war in the middle east? Because I have found that very interesting too, that a country as poor and as heavily sanctioned as Iran is managing to hold out the mightiest human forces the world has ever seen.
Love to play "Useful program or random startup" with these titles.
Does anyone know of something similar, but for aircraft and/or drones? I’ve been 3D printing model aircraft with my 8-year old but would be great to take it to the next level.
The miracle of 3D printing. First ghost guns, and now ghost rockets. Will be curious to see what prediction markets will have for these.
I helped out with a user interface redesign of OR many years ago. It was pretty incredibly unintuitive back then, and many hobby rocketeers paid for Rocksim instead.
With the current wars this will only gain more interest.
With CAE and flight simulation, this would be a game that I would actually enjoy playing.
I hope this is for students' project and for sending a gopro to the stratosphere?
What about misuse for weapon development? Does the project not massively cut R&D costs (hence lowering the entry hurdle) for potentially malicious actors on the planet?
Is there a similar drone design simulator?
There should be an agent for this :D . What kind of tooling do you folks use for simulation ? Maybe there is something to be done there. ?
Its a nice project !
you gonna need them!
Bookmarked :)