Thundercloud
Well-Known Member
- Joined
- Jul 6, 2017
- Messages
- 211
- Reaction score
- 60
Thank you very much for the added perspective. I'll roll again!
That's a huge overestimate of the loss due to vectoring. Watching the video, it looks like the maximum vectoring angle is only 5 or 10 degrees. The vertical component of the thrust goes with the cosine of the angle, so at worst it's cos(10) or about 98% of full thrust. (Of course we all know that there are other reasons that sims tend to be optimistic, but the thrust vectoring should be negligible.)I suspect that OR height estimates are a bit exaggerated, since some of the thrust will be angled, but I can live with the presumed error (likely on the high side) of 10-20%.
Yep, definitely.Wow! From post #36 it looks like there is a little bit of calibration for any given rocket model. Good Luck on the flight! Keep us posted.
OK, on to PID (proportional integral derivative) calibration, so that the device knows how much to change the angle of thrust to properly correct for your particular rocket veering off vertical.
What is PID?
Basic overview: https://www.mathworks.com/videos/un...art-1-what-is-pid-control--1527089264373.html
To actually tune the Signal R2, you need to hang it off a platform (ceiling, table), and measure the following:
Here is me hanging the Nerds rocket:
- Loaded Mass (kg)
- String Length (m)
- StringCOM (m)
- Rotation Time (s)
- COM-TVC (m)
- Average Thurst (N)
View attachment 377996
Interestingly, given rocket's relatively high baseline weight, the delta weight from two motors (F10 and F15) did not change the measurements all that much.
Once the measurements are taken, you input them into the Signal R2 app, hit "tune", and upload the derived PID value to the onboard computer:
View attachment 377997 View attachment 377998
At this point, I am ready for a test flight.
Today/tomorrow the winds are north of 20 mph, but Sunday looks calmer, and with some luck, I will test fly the rocket, and post the video then.
a
BPS Space has very good videos on everything involved. Fair warning though, be prepared to spend a bit of time watching, they are somewhat addictive. Joe Barnard is very good at producing clear and concise tutorials.That is interesting. Are there detailed explanations for determining the PID parameters, or is it all just a black box app?
Alan (old GNC engineer)
I just checked his web page. He has a video on his APP, but it just a show and tell on how to enter numbers into the APP. So it is a black box app, at least at this point.BPS Space has very good videos on everything involved. Fair warning though, be prepared to spend a bit of time watching, they are somewhat addictive. Joe Barnard is very good at producing clear and concise tutorials.
That is interesting. Are there detailed explanations for determining the PID parameters, or is it all just a black box app?
This is an immediate reply because I'm so excited but I've been doing just that, literally within the last 4 days! PIDs do work fine, but I've got a cold gas thruster system in the works and development on that has prompted me to start moving over to state space control! Way more flexible for multi-input multi-output systems like active rockets.
Who makes a 32 mm system? More information, please.I like the 32mm G12 reload.
Who makes a 32 mm system? More information, please.
I guess I should have been more concise; that's the answer I really wanted.Signal lets you program different PID gains for the two axes if you want.
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