It got a workout on this flight. I'm not quite sure why. The roll gain was set low due to the speed of the flight, so I was expecting not to see that much action on the spin can. Due to the wind, about 25 mph for much of the flight, the rocket would have been flying at a small angle of attack. I suspect that plays a role in what happens.
What kind of problems would a system like this encounter at Mach 1+ velocities? I love watching the video's on your channel and can't want to understand enough about electronics to try something like this myself. Great composites work as well.
Congratulations on the impressive work! As a part of my bachelor thesis I am also building an active roll stabilization system for a high powered rocket using canard fins. After going through a lot of literature I came to the conclusion that I really need to have free spinning tail fins in order to avoid control reversal and other effects. I was wondering if you could tell me how you built the spin can, i.e. what kind of bearings did you use. Did it make the rocket frame substantially thicker? Another question that I couldn't find an answer for on the internet is what the speeds (Hz) of the roll disturbances are, since my controller needs to be faster than them. I am planning on using gain-scheduled PID control or Sliding Mode Control and could happily share the results with you when I am done, if your interested....
Thanks. You'll have a lot of fun with the project. I have a video here that shows how the spin can is assembled. th-cam.com/video/CtMtY_vSzXQ/w-d-xo.html There is also a thread here that goes though the entire development process. www.rocketryforum.com/threads/i-could-use-just-a-little-guidance.122042/ There is a lot of discussion of the technology behind the system (you just have to wade through it!). Be sure to check out my other videos. There are probably a dozen or so that have used the stabilization system and/or spin can. When you get some results, join TRF and post them there.
The concept of the spin can is very simple. There is an air frame tube and then there is the spin can tube. The ball bearings go in the gap between those two tubes. Then, there is a ring attached to the air frame and another attached to the fin can, and again, the bearings sit between those two rings. The fins spin reasonably freely. The purpose of the spin can is to counter roll reversal, where vortices produced by the canards can cause the rocket to spin in the opposite of the intended direction. With the spin can, the spin can spins but the rocket doesn't.
@@Jiminaus50 Just wondering why roll corrections can't be blended into the canard pitch and yaw corrections. Seems like the spin can is a mechanically elaborate way of solving a problem that ought to be solvable in software. What don't I understand?
Roll and yaw/pitch control is blended. The relative gains can be changed as necessary. For this flight, roll control was turned down more than prior flights. For yaw/pitch to work, it is only necessary to minimize roll, not to stop it. I don't know about control via software. I think that design, such as CFD, could help avoid control reversal, and larger span canards with smaller span fins is another way. I can't do CFD, and the electronics aren't suitable for control of an inherently unstable rocket, so I go with the spin can.
Not the case on this flight. If you are not dropping through Mach, then the highest altitude would be with a longer delay. In this flight, the idea was to keep the entire flight below Mach 1. That required slowing down as much as possible before lighting the sustainer. But, you can slow down quite a bit with vertical stabilization without arcing over.
Probably not going to happen. But, the next flight in line, maybe, would be a larger N motor in the booster and then do the entire flight above Mach 1. That would be an interesting flight.
I don't understand. Unless the direction of intended motion is in line with 2 of the canards, all four canards will be used for whatever changes are needed in yaw and pitch. All four canards participate in roll control. All of the corrections are mixed, and each canard is directed separately.
Did you do any modeling or tests on this system with how the canards would cause the induced roll on the rear fins ? Or was the spin can built to completely negate those effects ?
@@julianchee2894 I had a flight that clearly demonstrated the effect. Based on that, I went forward with a spin can. I don't have the capability to model alternative fin designs. The spin can should negate much of the problem I noted, which was with roll, but there are probably interactions that cannot be completely avoided.
Hi, I'm from a school org and we're working on a very similar project. We have the mechanical aspect fabricated but the electronics are giving us problems. If you dont minded asking, what electrical components did you use?
The main part of the system is the UDB5 development board. It executes the flight program and has the PWM outputs for the servos. I have some programmable Hitec digital servos that seem to work well, and I have a Raven altimeter that can drop pins on the UDB5 to ground to separately turn on yaw/pitch or roll control. The servos directly drive the canards (no linkages). The flight program, which is intended for RC aircraft and heli's, has been heavily modified for rockets.
@@Jiminaus50 thats the route i was going for( the heli type) i wasnt sure if it would work as far as the servos having a fast enough response and the logic being able to keep up. its good to see that it does work! What program do you use?
There are limitations on the use of RC-type equipment. The response on yaw/pitch is relatively slow (from 1 to 5 seconds in my flights depending on speed). The servos are fine for that. More troublesome is the response to roll, which happens very quickly. Roll has to be inhibited so that the range of the gyros is not exceeded, so that yaw/pitch can work (which would be difficult with high roll rates), and so that cross sensitivity from the roll axis gyro doesn't affect too much the accuracy of the yaw/pitch gyros. My strategy is to use enough roll gain to reduce the roll that would otherwise occur, but not try to stop all roll. That's why there is roll in the video, even though the system has roll inhibition. The program is MatrixPilot, running on a UDB5 development board. The program is heavily modified for rockets (by Dr. Premerlani). Here's a link with some info. github.com/MatrixPilot/MatrixPilot/wiki
This is great work, a real advancement in the hobby. I am impressed!
This whole video absolutely blew me away. Incredible engineering and documentation!
Blown away guys. Awesome job!
Amazing how well that worked, especially in that Kansas wind! Thanks for sharing.
Great Job Sir !
That's awesome. Congratulations on the great flight! The spin can looks like it is very effective.
It got a workout on this flight. I'm not quite sure why. The roll gain was set low due to the speed of the flight, so I was expecting not to see that much action on the spin can. Due to the wind, about 25 mph for much of the flight, the rocket would have been flying at a small angle of attack. I suspect that plays a role in what happens.
Congrats Jim!
What kind of problems would a system like this encounter at Mach 1+ velocities? I love watching the video's on your channel and can't want to understand enough about electronics to try something like this myself. Great composites work as well.
I don't know what will happen above Mach 1, as I haven't done it yet. That's probably the next thing to try.
Awesome!
Congratulations on the impressive work!
As a part of my bachelor thesis I am also building an active roll stabilization system for a high powered rocket using canard fins. After going through a lot of literature I came to the conclusion that I really need to have free spinning tail fins in order to avoid control reversal and other effects. I was wondering if you could tell me how you built the spin can, i.e. what kind of bearings did you use. Did it make the rocket frame substantially thicker? Another question that I couldn't find an answer for on the internet is what the speeds (Hz) of the roll disturbances are, since my controller needs to be faster than them. I am planning on using gain-scheduled PID control or Sliding Mode Control and could happily share the results with you when I am done, if your interested....
Thanks. You'll have a lot of fun with the project. I have a video here that shows how the spin can is assembled.
th-cam.com/video/CtMtY_vSzXQ/w-d-xo.html
There is also a thread here that goes though the entire development process.
www.rocketryforum.com/threads/i-could-use-just-a-little-guidance.122042/
There is a lot of discussion of the technology behind the system (you just have to wade through it!).
Be sure to check out my other videos. There are probably a dozen or so that have used the stabilization system and/or spin can. When you get some results, join TRF and post them there.
@@Jiminaus50 wow, thanks for your fast and helpful reply! Yeah I'll make sure to post my results over there.
Love this! Congrats! Could you explain how the spin can works? Thanks.
The concept of the spin can is very simple. There is an air frame tube and then there is the spin can tube. The ball bearings go in the gap between those two tubes. Then, there is a ring attached to the air frame and another attached to the fin can, and again, the bearings sit between those two rings. The fins spin reasonably freely. The purpose of the spin can is to counter roll reversal, where vortices produced by the canards can cause the rocket to spin in the opposite of the intended direction. With the spin can, the spin can spins but the rocket doesn't.
@@Jiminaus50 Just wondering why roll corrections can't be blended into the canard pitch and yaw corrections. Seems like the spin can is a mechanically elaborate way of solving a problem that ought to be solvable in software. What don't I understand?
Roll and yaw/pitch control is blended. The relative gains can be changed as necessary. For this flight, roll control was turned down more than prior flights. For yaw/pitch to work, it is only necessary to minimize roll, not to stop it. I don't know about control via software. I think that design, such as CFD, could help avoid control reversal, and larger span canards with smaller span fins is another way. I can't do CFD, and the electronics aren't suitable for control of an inherently unstable rocket, so I go with the spin can.
@@Jiminaus50 Thanks for reply, these problems are well outside my understanding. Great job and great flight.
lot of delay between booster ejection and sustainer ignition, you'd go a lot higher if you could reduce that time
Not the case on this flight. If you are not dropping through Mach, then the highest altitude would be with a longer delay. In this flight, the idea was to keep the entire flight below Mach 1. That required slowing down as much as possible before lighting the sustainer. But, you can slow down quite a bit with vertical stabilization without arcing over.
Probably not going to happen. But, the next flight in line, maybe, would be a larger N motor in the booster and then do the entire flight above Mach 1. That would be an interesting flight.
Curious question. If 2 fins are sufficient to control pitch and roll (as demonstrated in your video before the launch), then why are 4 needed?
I don't understand. Unless the direction of intended motion is in line with 2 of the canards, all four canards will be used for whatever changes are needed in yaw and pitch. All four canards participate in roll control. All of the corrections are mixed, and each canard is directed separately.
Oh I get it now. With 4 canards, the rocket is able to pitch without first having to roll like how a fighter jet would.
Did you do any modeling or tests on this system with how the canards would cause the induced roll on the rear fins ? Or was the spin can built to completely negate those effects ?
@@julianchee2894
I had a flight that clearly demonstrated the effect. Based on that, I went forward with a spin can. I don't have the capability to model alternative fin designs. The spin can should negate much of the problem I noted, which was with roll, but there are probably interactions that cannot be completely avoided.
Hello, did you used which type camera module?
Very inexpensive. A key chain #16 and maybe a "Replay" pro. Nothing special.
Hi, I'm from a school org and we're working on a very similar project. We have the mechanical aspect fabricated but the electronics are giving us problems. If you dont minded asking, what electrical components did you use?
The main part of the system is the UDB5 development board. It executes the flight program and has the PWM outputs for the servos. I have some programmable Hitec digital servos that seem to work well, and I have a Raven altimeter that can drop pins on the UDB5 to ground to separately turn on yaw/pitch or roll control. The servos directly drive the canards (no linkages). The flight program, which is intended for RC aircraft and heli's, has been heavily modified for rockets.
@@Jiminaus50 thats the route i was going for( the heli type) i wasnt sure if it would work as far as the servos having a fast enough response and the logic being able to keep up. its good to see that it does work! What program do you use?
There are limitations on the use of RC-type equipment. The response on yaw/pitch is relatively slow (from 1 to 5 seconds in my flights depending on speed). The servos are fine for that. More troublesome is the response to roll, which happens very quickly. Roll has to be inhibited so that the range of the gyros is not exceeded, so that yaw/pitch can work (which would be difficult with high roll rates), and so that cross sensitivity from the roll axis gyro doesn't affect too much the accuracy of the yaw/pitch gyros. My strategy is to use enough roll gain to reduce the roll that would otherwise occur, but not try to stop all roll. That's why there is roll in the video, even though the system has roll inhibition. The program is MatrixPilot, running on a UDB5 development board. The program is heavily modified for rockets (by Dr. Premerlani). Here's a link with some info. github.com/MatrixPilot/MatrixPilot/wiki