This is something I can only dream off. UK doesn't have the room to fly not do we have a system that would let you. Good luck with the project. Amazing effort
I'm lucky to be able to do this each year. Hopefully, I won't make a single mistake this year, because that's all it takes.
But, you can still help me plan my flight if you want to, even if you can't do the flight yourself. You have to catch me doing something wrong, but that's not all that hard. If you check back on this thread, you will see I incorporated many suggestions into the flight last year, and even more into the flight this year.
First step is to do the flight profile. The first pic shows a diagram of the rocket, with the stabilization spool, and the second pic shows the overall RockSim simulation. The projected altitude is about 117K (RasAero, with the approach I use for multi-stage flights, is a little more generous at 128K on the same overall timing). After burnout of the booster motor, the booster will be separated, and then the stabilization spool will provide active guidance for a while. At a time to be proposed here, the stabilization section will be separated and then the second stage motor will light. This is the separation sequence that I tested in the last stabilization test flight.
https://youtu.be/umoduWiQb-o
Fortunately, I have the 2014 data (the rocket without the stabilization section) to help formulate the plan. The third pic shows the actual altitude profile for the 2014 flight and the corresponding simulation. The configuration here is to drop the booster after burnout and then the second and third stages coast together. The 2015 simulation is also shown (it goes a little lower because of the weight and drag of the stabilization spool). The 2014 simulation is pretty good, particularly given that it wasn't perfectly vertical.
The fourth pic is the velocities from the 2014 and 2015 simulations. I'm not showing the actual data because the accelerometer data is affected by errors in the accelerometer calibration, and velocity calculated by altitude is noisy. However, it should fall just below the 2014 simulations based on the altitude data. The pic shows that the maximum velocity reaches about Mach 1, and that I am proposing to light the 2nd stage motor (having it up to pressure) at 15.4 seconds. This is at a simulated velocity of around 550 ft/s. The actual velocity is likely to be a little lower because the simulation doesn't fully capture the drag from my canards.
Here is the logic for picking that velocity. I want the velocity to be reasonably low in order to keep the top speed during the second stage burn as low as I can. From the simulation in the second pic, the 2nd/3rd stage stack will reach about 1,900 ft/s. That would be the fastest that I've ever run a stack, and this is the point of maximum risk I think. On the other hand, staging at a bit higher velocity doesn't have much of an altitude penalty, and would reduce the weather cocking that will occur in the time between when the stabilization spool is separated and the motor lights.
So, that's the plan for the first segment of the flight.
Jim