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.
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 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.
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/
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.
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.