I have a large H frame quad and noticed the new "H Frame" option in MP. I had always run my quad as an "X" frame, which works just fine. I posted a query asking if there were any special features that came with this choice and was told, no, it's just to help people with their selection. OK, sure, why not. So I switched my frame selection from the "X" that it had been to H. Before I had a chance to fly it I did a whole lot of rewiring, including new ESCs and forgot about the choice.
Took it out to fly this morning for testing, lifted it off and it started yawing like nuts. I managed to get it back on the ground without damage, but just barely. I think I bounced it off my truck in the process. I did a few 6" hovers, trying to overcome the yaw, but the controls were acting crazy. Knowing my gift for making stupid mistakes it was then clear to me I must have got my motors mixed up with the new wiring. So back to the garage I go to undo my error.
Funny thing....All the wiring was right. And my RC transmitter was right. WTF? So then I started going through MP looking for any setting I could have screwed up...and remembered the H frame selection. Hmmmm....Nah, couldn't be. But I set the frame type back to X and took the quad outside.
Rock solid hover. No yawing.
Switched it back to H frame, retested, and welcome to crazy town again.
Now looking closely at the diagram in MP shows the colored motor assignments between the + and the H to be different. If you've been flying an H frame under the X configuration it seems like you have to redo your motor assignments if you change your configuration otherwise you'll get the surprise I did.
I'm not sure why the motor assignments are so different but this has the potential to bite a lot of people.
Replies
What confused me is the orientation of the H shown on Mission Planner with the front in the middle of the horizontal bar of the "H", I've been using one of the ends of the horizontal as the front. Rotated back to "X".
hi,
i built a quad H recently. which configuration should I use ?? the quad X frame type with motor directions of quad H ?? or motor directions of quad X
Hi Tom,
The problem you are having is because the H frame reveres the props so that any frame twist helps the quad yaw rather than working against it. However, motor numbering is the same.
Thanks for pointing this out. We will make sure the H frame is properly represented on the Wiki.
I am very glad you didn't damage anything!! And thanks for the heads up!
The objective of other motors assignment in a H frame is to solve the sometimes difficult yaw in a non perfectly rigid frame.
If your frame would be perfectly rigid, there would be no difference between X and H configuration.
With the X motor configuration and an H frame, the rotation direction of motors are counter acting the wished yaw effect because of the way an H frame flexes.
If you are happy with your H frame using an X motor config, you do not have to choose H firmware.