OpenRocket
openrocket.info
openrocket.info
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 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.
Look into the physics of archery, which has similar accellerations albeit of a narrower tube. The choice between a heavier/stronger arrow v a lighter/flexible shaft is the entire game.
Amateur rocketry people try very hard to make their rockets symmetrical.
Hobby rockets have to be stiff enough not to banana. I don't think it is figured into model rocketry beyond that.
Flex doesn't really become a concern with carbon fibre until you approach Mach 3. I say this because I've built two rockets of an identical design philosophy; one for 54mm motors and one for 75mm motors. The 54mm motor rocket did M2.64 and I could fly it again today if I wanted. The 75mm rekitted itself at M3. It failed where I'd not reinforced the hand rolled airframe that I was flying. 4 wraps of 2x2 200gsm twill CF. Same number I used on the 54mm fine.
For both of these rockets the vast majority of the airframe is directly over a aluminum motor casing that is a rigid body. These things are grossly over-engineered when compared to the pressures/forces they see.
There is also the European Rocketry Challenge in Portugal: https://euroc.pt/
obrigado!
https://www.safran-group.com/news/have-you-heard-about-rocke...
Maybe you can contact the school and find out more?
How hard is it to get started for amateurs? Are rules/regulations problematic?
The UK regulations are fairly sensible and they won't let you do anything stupid at one the regional meets. Just start with something small (A/B/C motor) and work your way up from there. Don't try to start with a K motor, 2 stage or liquid propellant and you'll be fine.
Where are you based?
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.
I know you want to tell us all about the amazing (sincerely!) stuff under the hood, but to users, the interface is the product.
I'm into rockets, and clicked the link earlier today. I shared the suggestor's view, but didn't bother to post. I came back now, saw the comment thread had updated significantly, noticed that OP had addressed the suggestion, clicked again -- and noticed, hey wow, there are cool screenshots now, these are a lot more interesting, this is better than I thought!
Usually when there's no screenshot or video for GUI apps I assume it's because the creator is not proud of it, so a sign that the UI will be shit.
A short looping video of the software in action might also be good. But a lot more effort.
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
> on the home page
and I meant it
I think I need to go for a walk.
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.
89 kilometers
You also have to try to account for every little possible failure mode before launching which is why rockets seldom succeed on the first attempt.
And then dealing with authorities to create new launch sites and permits which probably hasn’t been done in decades in Canada.
So the jump from the former to the latter is... significant.
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/
I think I'll go land on Mun and Minmus now...
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
Cool. Is there more information on their rocket or a video?
Also here is our technical report: https://spaceteam.at/wp-content/uploads/2025/10/Technical_Re...
Feel free to ask any questions. I’m the software lead of the project :)
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.
From a conventional perspective Iran is by all means "losing" the war. However, the United States and the majority of the world desperately want the strait to be opened and have so far been unsuccessful in preventing Iran from blocking it. The US is also greatly interested in regime change, which has also been unsuccessful.
Trump doesn't car about regime change. Just like in Venezuela, his plan is to kill leaders until there's one that can make a "deal" (whatever it means).
Most of our allies feel that they can give us the middle finger when we ask for help. More people around the world than ever before now think that US and Israel are the biggest threat to world peace.
This is new and uncharted territory for us. We will pay a bigger price for this over the coming years and decades than whatever we did to Iran.
> don't even have boots on ground
Anyone with half a brain cell knows this would be the biggest strategic, tactical and political blunder of the century
> What do they hold, exactly?
What they hold exactly is:
- middle eastern countries who've been greasing Washington's palms for influence and protection received 0 protection, it'll take decades to rebuild any trust here
- Americans deserted their bases in the region instantly, they are now damaged or destroyed, the US conveniently ask satellite image providers to delay the release of new data
- Lost a bunch (most?) of radars from their early warning system in the region
- US sailors seemingly set their own ship on fire to avoid deployment
- Depleted israel interceptor stocks, more and more things are passing through the dome
- the US spent 12b so far to fuck up Iran, Russia made 6b from the gas price increase in the meantime, big brain move
- the US pulling out of asia to send more shit to the middle east, eroding trust of countries like South Korea
- Israel support in the US is falling fast, in the EU it's gone
- the price of everything will slowly rise, because everything we use rely on gas one way or another, they've been sanctioned for 50 years they don't give a shit anymore.
- the US showing their complete lack of strategical vision, saying something on monday, the opposite on tuesday and denying they even said either things by wednesday
Stop reading r/iran or CNN or whatever bs you pump into your brain.
This war sucks but it's very far from "Iran is holding".
Iranians don't like their current government much but they don't particularly like getting fucked up by Israel and the US either, especially when you kill 170 kids on day 1 and then lie about it on live tv. How did it go in Syria, Libya, Afghanistan, Iraq? Yeah, not so good. It's always about "preventing wars" and "bringing freedom", but it ends up being "bringing wars" and "consolidating authoritarian regimes"
> a country as poor and as heavily sanctioned as Iran
It's one of the oldest civilization in the world
It's not poor by any means, it's the 20th economy in the world
They produce as many engineers per year as the US, and they're not financial engineers or saas coders, fyi:
> mid-14c. enginour, "constructor of military engines," from Old French engigneor "engineer, architect, maker of war-engines; schemer"
Sanctioned for half a century means they developed other ways to live and survive
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 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 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.
Is there a parts list?
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.
Maybe we (or somebody in, say Ukraine or Rojava) will need this to defend themselves from the actors having access to missiles right now.
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.