- 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.
- 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.
- 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.
- There is a game on Steam where you can design and fly your own aircraft. Would be fun to then try to 3d print the successful ones. But I can't remember the name of the game, sorry.
- 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.
- Why would you put that evil thought into other people's heads? Now someone might do that
- OpenRocket has a little optimizer built in but of course it neglects structural integrity which it knows nothing of…
- I figured it was a typical no-info HN title; I was happy to discover it actually conveyed some meaning.
- 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.
- 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!
- 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.
- Model rocketry has long been a gateway drug to get kids interested in STEM subjects.
- Helps to have terrain around your country that makes it one giant fort
- Love to play "Useful program or random startup" with these titles.
- 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.
- 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?
- 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...
- Thank you so much for sharing this video, it's just amazing to see a bunch of young amateurs getting so excited about things that would have been virtually inaccessible 20 years ago.
- 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.
- Distance is usually the wrong measure in space. Something like delta-v will give you a much better scaling as once you manage to get something to orbit the rest is actually a lot closer than it would seem on the ground.
Not to say the effort somehow becomes peanuts, cheap, or easy... but the jump in delta-v needed to go from "100 km vertical ascent" to "hit the moon 350,000 km away" is more like a ~6-7x increase than a 3,500x one. If the moon were instead 700,000 km away the factor would still be ~6-7x.
Cool site for delta-v estimates https://deltavmap.github.io/
- And you need a serious amount of money, effort and expertise to each 100km with a rocket.
- Amateur rocketry achieving orbit would be significant. Reaching the moon would be substantially more difficult.
- The miracle of 3D printing. First ghost guns, and now ghost rockets. Will be curious to see what prediction markets will have for these.
- you get some good, you get some bad.
Building a rocket shell is probably just fine: you need to fuel yet - that you can't 3D print. probably fine...
Overall 3d printing is a lot more than ghost guns and ghost rockets. That the conversation dominates this small sub-section reeks of 'think-of-the-children' screeching that hides explicit power grabs in regulation and surveillance with the main intent seemingly to be 'enforce copywrite' (of only the big players that can afford to throw their weight around).
Fear pushes people's buttons.
- i've recently had youtube randomly suggest me a video where this dude was building his own opensource manpads, with a single rocket costing under $100 in parts (there was no explosive payload so that makes it just a rocket and not a missile, i guess). not long after, someone posted it here on hn but i think it's been removed (by the mods, i imagine) since.
i find these projects both fascinating and terrifying. seeing a single person building what normally involves huge defense corporations and government contracts, these things in their bedroom is amazing. it shows how information wants to be free and how ingenious people can get with whatever motivates them.
- The knowledge and skill in the HPR (high power rocketry) hobby is definitely there to build basic weapon systems. Active stabilization using movable fins is a thing, onboard gps and flight controllers are also a thing. Nobody puts it together end to end though because it gives the whole hobby a bad look and the hobby governing organizations strongly discourage it too. Also, fortunately, most people have no interest in mass murder either. Much of the hobby is old engineers who are retired but still want to work on engineering projects in their garage.
- > someone posted it here on hn but i think it's been removed (by the mods, i imagine) since.
The submission: https://news.ycombinator.com/item?id=47425297 "Tech hobbyist makes shoulder-mounted guided missile prototype with $96 in parts" - https://github.com/novatic14/MANPADS-System-Launcher-and-Roc...
Seems to have almost as many comments as points, so guessing it got pushed down the frontpage list because of the "anti-flame-war" thingy HN has.
- It was here on HN (441 points)
- > with a single rocket costing under $100 in parts
Is there a parts list?
- I believe it is the same project that was discussed here a few days ago: https://news.ycombinator.com/item?id=47385935
- I know; I thought they'd have a handy parts list on their new site. But you are right; I should have looked in their Google Drive docs. There's a section - "Bill of materials and cost breakdown", but details are buried somewhere. Thanks, though.
- Need itar to be defanged first.
- With the current wars this will only gain more interest.
- But hopefully not that kind of interest.
Model rocketry, as a hobby, enjoys a limited amount of regulation, at least in the US. In large part, that is because the community has been very good about self-policing. Most folks who are serious about the hobby closely follow the safety guidelines published by the two national organizations (Tripoli and NAR), and steer newcomers to as well. Serious accidents are few and far between, intentional damage even more so. Compare this to, say, drones, which seem to be more widely embraced by the public, but are much more closely regulated and have been implicated in a number of serious incidents like https://abcnews.com/US/drone-operator-charged-hitting-super-... . Model and amateur rockets are cool. Folks mis-using them are going to run into a lot of pushback from pretty much every direction, because it'd only take an incident or two to ruin the hobby for everyone.
- similar situation in the UK. It would only take 1 or 2 idiots to ruin it for everyone.
- I hope this is for students' project and for sending a gopro to the stratosphere?
- you gonna need them!
- Is there a similar drone design simulator?
- idk off hand but i'm sure there's something like OpenRocket for R/C airplanes. Where you put in the dimensions, wing type, mass distribution, and other stuff and it tells you if it's aerodynamically stable or not. After that you put in an ardupilot autopilot+gps+airspeed sensor and there's your drone. iirc, with ardupilot you can do automated flight planning like "fly to this gps coordinate, orbit for 10 minutes, fly home" etc.
to relate to OpenRocket, some people are into rocket powered gliders and use autopilots to make flying them after launch easier. It's basically a fly by wire setup so controlling the glider is on easy-mode with the autopilot doing most of the work keeping things stable while the human with the controller just focuses on making the slow circles back to the launch area. These autopilots are how typical quadcopter drones can be flown easily without the wind and 4 motors causing havoc constantly.
- Have you seen https://store.steampowered.com/app/2060160/The_Farmer_Was_Re...? It is not a drone simulator more like a problem solving game using a drone.
- Bookmarked :)
