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Be really careful. Adding guidance to a hobby rocket may classify it as a missile, and you will need to start looking into ITAR.
Earlier quoted context omitted.
Specifically, you need reaction time faster than sqrt(l/g), where l is the distance between the engine and the center of mass, and g is gravity. But l=30 cm is still with the range of commodity hobby servos to vector the engine. The same effect makes walking robots harder at small scale, unless they cheat by having large feet and stiff ankles.
How did you get the sqrt(l/g) figure? I can see how this is dimensionally correct and passes a sanity check, but why is the coefficient one?
If you can react 2x as fast the control problem is easy. If you can react 1x as fast, the control problem is feasible but requires accurate tuning.
For average-height humans on earth, the height of the center of mass is about 1.3m, so sqrt(l/g) is about 350 mS. Human response time, from the inner ear to the ankle muscles is about half of that. That gives some intuition for how hard it is to balance with 2x faster response. Balancing a yardstick on your finger is closer to 1x faster response.
A team of engineering graduate students with a bit of funding might succeed, but the cost and custom hardware would be pretty high. The problem also gets more difficult as the rocket gets smaller.
Also, failed rockets are flying bombs, not something to be done lightly.
Earlier quoted context omitted.
Ah wow I watched a bunch of his videos last summer but forgot to check up on his progress. Incredible! I wonder what scale you would need to get the rocket into space/orbit? SpaceX should fund this guy to find out, could prove to be a valuable bootcamp for real SpaceX employees in the future?
>I wonder what scale you would need to get the rocket into space/orbit? There's a great "what if" xkcd about using solid fuel model rocket engines (the same type used in BPS.space's rockets) to get to space and orbit. https://what-if.xkcd.com/24/ The summary is that you may be able to use a stupendously large number of them to get to space, but orbit is physically impossible. You'll need a different propulsion method…
BPS.space is attempting it. Test Launch: https://www.youtube.com/watch?v=QQt-9SSJ51c Test Landing: https://www.youtube.com/watch?v=lXy-x6lkQvQ
This isn't a computing hardware or software problem, it's an aerodynamics and propulsion, structures problem. A team of engineering graduate students with a bit of funding might succeed, but the cost and custom hardware would be pretty high. The problem also gets more difficult as the rocket gets smaller. Also, failed rockets are flying bombs, not something to be done lightly.
You can see what spacex (probably) does to turn it into a tractable problem for real time control in http://www.larsblackmore.com/iee_tcst13.pdf (Blackmore leads entry, descent, and landing at spacex).
Years ago, I remember reading this guy's website where he was building a homemade cruise missile: https://www.theage.com.au/world/diy-cruise-missile-20030604-... I don't know whether he got shut down by the authorities or not.
I was actually curious how cruise missiles were defined in itar. The definition of missiles is really broad and actually includes lots of UAVs. > “Missiles”. (All) Rocket systems (including ballistic missiles, space launch vehicles, and sounding rockets) and unmanned aerial vehicle systems (including cruise missiles, target drones, and reconnaissance drones) “capable of” delivering at least 500 kilograms payload to a…
It isn't quite a model rocket, but there is an interesting video of someone making a single-fan drone using thrust vectoring. Not quite like a Falcon 9 but the same idea, vertical take off and landing, and shaped like a rocket. https://www.youtube.com/watch?v=RMeEh5OUaDs
I don't think there's any open-source software for this, but the software isn't really the problem anyways. It's more about getting sensors that are accurate enough and actuators for thrust direction and power that are accurate and fast enough. I don't think there's anything off the shelf for this, and building and testing it, at that scale, is possible, but not cheap or easy. Once you get all of that together, the software is a relatively small and simple problem, and probably too specific to your exact setup for it to make sense to open-source.
Probably the biggest problem is that model rockets use solid-fuel engines, which cannot be controlled once ignited and probably don't have the greatest consistency in thrust and time. Short version is you ain't gonna do a propulsive landing with that. You'd have to build your own micro-scale liquid-fuel rocket engine. I don't know that much about building rocket engines, but it sure looks like building ones on the scale to take commercially viable weights into orbit is very hard. I'm going to bet that building one on a micro scale would be substantially harder and probably require the services of several experts in the field.
If you're interested in the area, see what info you can find about military missiles, like for MANPADS, guided anti-armor missiles, and some of the lighter AAMs. Every one I've heard of uses solid-fuel engines too, but they do have good control systems for guidance. I don't think any of them care much about the exact thrust levels, just get it going good and fast and the active guidance systems can handle the rest. But you're gonna need that precise thrust control if you want to land propulsively. Relatedly, if you tried to actually build your landable model rocket, I would expect the appropriate Government agency in your jurisdiction to take a very keen interest in exactly what you plan to do with these things. It may involve spending lots of time and money to convince them that you definitely won't give any of your stuff to whatever the relevant agency considers to be a terrorist group or rouge state.
Be really careful. Adding guidance to a hobby rocket may classify it as a missile, and you will need to start looking into ITAR.
Not an american, but I thought ITAR just restricted export (including of information though), hence the I(nternational) and T(rade)?