Gyro on taileron/elevon/delta?
02-03-2013 | 04:22 PM
#26
RE: Gyro on taileron/elevon/delta?
With all the discussion about how gyros make the model more fun, and the discussion here about how to do a delta wing with elevons I decided to go ahead and give it try using the concept of mounting the gyros for the elevons at 45 a degree angle off the centerline that was discussed here. I put these in my P20 powered Crusader III. The gyros are Futaba 430’s which are really small, which is a good thing since I had very little room for them.
Bottom line, this worked great. I have had a few flights this weekend and the model really acts like it is on rails. On a calm day the model flies very smoothly anyway, but being light and having a light wing loading it gets bounced around when the wind blows. The most notable changes are that it locks in on knife edge (did ok before, but not this good), and the landing pattern is easier. A small model and my eyes had some trouble at times on base, the model is much more solid now which helps.
I thought that a little technical explanation of why this works might help some of you who might be considering a gyro setup like this. For conventional setup the gyro is aligned with the axis of rotation that the control surface(s) can rotate the model about. But for an elevon that axis is not aligned with any of the traditional ones. If you deflect the right elevon on a delta wing up, the model will both pitch up and roll right, so the rotation axis lies between the pitch and roll axis, and this is the axis you want to align the gyro with since this is the axis the surface can control the model about. A point of confusion that has been mentioned earlier is that most delta wing are more sensitive in roll than in pitch, after all you can do a roll in a second but a loop takes much longer. Problem with this is that the rate at which you can change the flight path has nothing to do with pitch rate. When you pull back on the stick the model pitches up fairly quickly and then the aerodynamic forces equalize and the pitch rate drops down to the rate that the flight path is changing by, and the gyro is damping pitch rate, not flight path rate. So in reality the pitch rate and roll rate probably will not be that far apart, so the 45 degree setup is a pretty good guess.
In my setup I have a yaw gyro also, which has its own gain channel. The elevon gyros use a “Y” harness to control their gain. I am using a DX18 radio and one of these days I am going to assign both gain channels to the left trimmer and use the sub trim to handle the difference between them. If you mount the gyros like I did, with the “V” formed with the mounting base pointing forward, the right gyro goes with the right elevon. If you point the “V” to the rear the right gyro goes with the left aileron.
I hope this is of some use to some of you, got to go watch the super bowl now.
Bottom line, this worked great. I have had a few flights this weekend and the model really acts like it is on rails. On a calm day the model flies very smoothly anyway, but being light and having a light wing loading it gets bounced around when the wind blows. The most notable changes are that it locks in on knife edge (did ok before, but not this good), and the landing pattern is easier. A small model and my eyes had some trouble at times on base, the model is much more solid now which helps.
I thought that a little technical explanation of why this works might help some of you who might be considering a gyro setup like this. For conventional setup the gyro is aligned with the axis of rotation that the control surface(s) can rotate the model about. But for an elevon that axis is not aligned with any of the traditional ones. If you deflect the right elevon on a delta wing up, the model will both pitch up and roll right, so the rotation axis lies between the pitch and roll axis, and this is the axis you want to align the gyro with since this is the axis the surface can control the model about. A point of confusion that has been mentioned earlier is that most delta wing are more sensitive in roll than in pitch, after all you can do a roll in a second but a loop takes much longer. Problem with this is that the rate at which you can change the flight path has nothing to do with pitch rate. When you pull back on the stick the model pitches up fairly quickly and then the aerodynamic forces equalize and the pitch rate drops down to the rate that the flight path is changing by, and the gyro is damping pitch rate, not flight path rate. So in reality the pitch rate and roll rate probably will not be that far apart, so the 45 degree setup is a pretty good guess.
In my setup I have a yaw gyro also, which has its own gain channel. The elevon gyros use a “Y” harness to control their gain. I am using a DX18 radio and one of these days I am going to assign both gain channels to the left trimmer and use the sub trim to handle the difference between them. If you mount the gyros like I did, with the “V” formed with the mounting base pointing forward, the right gyro goes with the right elevon. If you point the “V” to the rear the right gyro goes with the left aileron.
I hope this is of some use to some of you, got to go watch the super bowl now.
02-04-2013 | 05:25 AM
#28
My Feedback: (28)
RE: Gyro on taileron/elevon/delta?
The delta wing or other wings that have a lot of sweep have a dutch roll tendency, to stop this put a gyro on your rudder. It does the same thing as a yaw damper on a full size jet. You will see a tremendous improvement in roll and pitch stability.
