How do you propose to maintain SS-520-5's ratio of propellant to structural mass as you scale it down, whilst also maintaining the pressure required to attain the specific impulse of its stages?
With a Unicorn Fart igniter
If your objective is to get there in a small size form, then solids are most likely the best solution. Not only are they generally superior in terms of density Isp, they also don't require additional plumbing and combustion chambers ie. for blow down systems. So, the mass ratio for solids are inherently better than blow down and other pressure fed liquids.
Thermal control is one of the hardest parts of high performance rockets. A solid with the necessary delta-v is going to need a lot of insulation. It might be possible to do this with higher thrust and a shorter burn, but that will stress the rocket badly and add weight. I am going to triple down and say the Op @RGClark should make a very detailed design and then start making demo hardware.
That's where you utilise your propellant as much as possible to both insulate the casing and provide the propulsion impulse. Also possibly utilise solid gas generation film cooling for nozzle if necessary.
1, 2, 3, and 4 can be taken care of for 21 grams if it only needs to transmit long enough to tell you it made it to orbit.
The electronics for active guidance isn't the hard part, it's the actuation system. Some cold gas thrusters are very small and light but the tank that feeds them isn't. I suspect that thrust vector control could be done in a minimum-diameter rocket with a lot less mass and cost than is commonly expected, but it will be a couple of years before I could prove it.
No doubt on being clever with the propellant for insulation. The details of that will certainly require development, testing, and tinkering to get that correct. Same thing with liquids. Thermal management is tricky, but by no means impossible.
Don't forget valves and powering them. Valves are always tricky in high performance rockets.
Valve driver circuits are a little tricky but not that hard (I’ve done it professionally). Tank mass is a bigger issue if you’re trying to see how close an amateur could get to a rocket that could get to orbital velocity. But I think it could be done with just solid rockets and TVC.
Do you have an example of a valve? Pressure differential, flow rates etc?
Not for you, Adrian, you are what we can an “expert” and there are very few of you around!
Moog makes great components! Do you know which of those you will need for a launch vehicle? How many?
There are several people in the hobby who have designed small electronics around modern chip-scale commercial gyros and successfully propagated attitude knowledge from them. That's as far as I have gotten so far. Some are rocketry electronics manufacturers but others are just people doing it for their own hobby enjoyment. Adding a control loop isn't a big leap from there, and a smaller number have done it with canards for atmospheric flight. To work in a vacuum, the control actuator needs to be a thrust vector controller and/or reaction control jets. A couple of hobbyists have successfully controlled motor thrust direction, but not in a minimum-diameter rocket yet as far as I know.Not for you, Adrian, you are what we can an “expert” and there are very few of you around!
Were you looking at TVC?
Isn't comm loss over certain parts of the world still the norm even for professional launch vehicles? For the radio, I was being pretty hand-wavy with the link to the Featherweight GPS tracker. Something that size is possible, but it needs a GPS receiver that does not have altitude or velocity lockouts. I haven't spent a lot of time looking into those options. The Multitronix Kate has an unlocked GPS, but I don't know if it's driving the larger size for that unit.
For me this thread isn't about making a launch vehicle (that delivers a payload) but instead, just poking at what it would take to extend the boundary of amateur rocketry from its current location at the suborbital edge of space, to having part of a rocket orbit at least once around the world. I've always assumed that it's a huge leap, and I don't expect anyone to even make a serious attempt (I'm certainly not planning to myself), but it's interesting to me to do the math and think about what the limiting factors really are, and think if there are ways around them. Yes, getting approval is a real problem and would need to be part of the plan up front for a serious attempt, but since I'm not trying to make a serious attempt I'm content not to worry about it.
That is a good point. The details are the hard part of rocketry in my opinion and that is why they are restricted by some governments and often held as trade secrets by companies in the business.
This is the most sensible invocation of ITAR that I’ve seen on TRF.
Which I don't think applies here.
