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.
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.
It’s beautiful to see. They have put in such extreme amounts of hard work to get that thing into the air. Designing a robust affordable liquid propelled rocket from scratch is hard. There are so many design decisions, complex simulations, manufacturing difficulties, and tests for every little part of that 11+ m rocket. Accounting for extreme forces, heat variations, vibrations, wind, atmosphere, liquid sloshing, rotation, etc during ascent and descent. It’s not only mechanical/aviation engineering but also software, electrical, sourcing donations, documenting everything in forms of design and risk assessment reports etc etc.
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.
Indeed, there are so many different ways a rocket a fail. Launch rail buttons detach, motor chuffs, motor explodes, fin falls off, structural failure (banana), parachute doesn't fire, parachute doesn't deploy, parachute detaches - to name just a few.
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).
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.
Everything you've said is correct, but Delta-V scales logarithmicly with fuel load - you need to carry the new fuel. So for purpose of discussing altitude (a valid way to look at getting to the moon) the size of the rocket, and the fuel expended, does in fact grow much closer to linearly.
What I actually started with was comparing Electron to the current bos.space rocket and seeing the relationship was nowhere near linear. The above is the largest component of why I could think of but there is always more than 1 thing going in.
