Tried something different..... here are the results.

[Benjamin Rowland]

So I got the itch to try a coaxial today, but my motors are too fat to do the traditional stack with the motor-mount plates I have at the moment, so I tried offsetting them instead.

Here is a picture of before:
View attachment 10702

Here is a picture of what I mean by offsetting the motors (inspired by another forum user):
View attachment 10703

Here's what it ended up looking like:
View attachment 10704

So basically I ended up with a Cinestar X8. But the top motors are inboard and the bottom motors are outboard (hope that makes sense). I only got to run two flights, but they were long ones, and I got so-so results. I'm using a Hoverfly Pro, which flies awesome in my typical flat 8 layout (almost 1600 flights). Initially I had to reduce the gain by a fair amount to get it flying decent. It started to fly decent, but not as good as what I'm use to.

Here's the main issue I ran into - it would yaw a bit here and there. That gave it a floaty feeling, not as locked in as I'm use to. The yawing would drive my camera op nuts. I've got a few theories as to why it is yawing a bit:

• One motor isn't totally lined up correctly. I had to eyeball it all. There might be one that's off.
• All the top motors spin clockwise on the top and it is reversed for the bottom. Having one set of motors closer in to the center could be causing some funkiness.

So I'll double check motor alignment. I may reverse the offset of the motors on the back booms.

So why did I even try this? To do a bit of experimentation. Also, I wanted to try a coaxial. And last, I've been wanting to put bigger props on without having to buy longer booms. I'm the type that either works with what I have, or ponies up the cash for the best - there's no in between. So it looks like I may need to invest in longer booms. I'll follow up with further results tomorrow, but I don't think I'll be sticking with this setup. But I'm glad I gave it a shot!

Let me know what you folks think...

 

[DucktileMedia]

Its gotta be something other than the config itself. Mine never does any of that. Although you're making me want to try an octo now Just too damn big and you get props in view when you dip forward.

 

[Benjamin Rowland]

But are your motors offset? I think having the CW set closer in than the CCW set is causing a bit of weirdness. It's not crazy, it just yaws a bit when it corrects for a small breeze, which it didn't really do before.

 

[SleepyC]

I don't have a pic, but I did the same thing with my Y6 when I first set it up and it felt weird. I re-did the mounts and made the motors perfectly on top of each other (normal coax) and it felt normal. It's weird since it's just a few inches, but it made a difference. I am also using a HFP.

I'm no expert by any means, but I had the same result.

 

[RTRyder]

But are your motors offset? I think having the CW set closer in than the CCW set is causing a bit of weirdness. It's not crazy, it just yaws a bit when it corrects for a small breeze, which it didn't really do before.

Try staggering the rotation of the motors on each plane same as if they were the only motors, that should eliminate any weirdness created by having one set in closer to center than the other. The opposing rotation will balance it all out on each plane and should make it stable yawing in either direction. You may have to do some wire swapping both on the motor/ESC and at the flight controller to get things sorted but it should resolve any imbalances.

Ken

 

[jfro]

RTRyder.........

I just built an x8 with HFP. In the manual they say to have all top motors turning clockwise and bottom ccw.

I just was told that it would fly better if I swapped two opposing arms and have CCW turning props on top and CW on bottom for those two opposing arms. (ie. front left back right or vice versa).

Told it would handle the yaw better when medium to faster flying and was generally a better configuration amongst some other ideas.

Was told to swap out the props on those two arms as well as the servo wires.

If one does this do you swap both the 3 wires from the ESC to the HFP Flight control board and do you also swap 2 of the 3 wires from the ESC to the motor to reverse them?


Benjamin, is that floaty feeling you talk about a good or bad thing for filming?
also, what is the leg or arm sticking up for ?

 

[DucktileMedia]

No I don't have that offset. The only thing I have a complaint about is it is very hard to maintain a certain altitude. I disabled the AH but still it's either going up or down at some rate. Very flat throttle curve already, so that's not it. But the yaw is pretty good. Occasionally there is a very minor spin up that affects yaw but it is rare and very minor. What matters most is being able to carve a straight line going up or down. I think Hoverfly likes tops/bottoms turning opposite directions. Rather than the staggered style some others use. It does make sense the staggered way would be better though.

 

[Benjamin Rowland]

Try staggering the rotation of the motors on each plane same as if they were the only motors, that should eliminate any weirdness created by having one set in closer to center than the other. The opposing rotation will balance it all out on each plane and should make it stable yawing in either direction. You may have to do some wire swapping both on the motor/ESC and at the flight controller to get things sorted but it should resolve any imbalances.

Ken

I'm with ya on that. I'll give it a try tomorrow.

At some point though I think I'll figure out a way to turn it into a traditional coax. But I'm also thinking that the props will hang down too low and I'll likely go back to a flat octo. We'll see...

 

[matwelli]

Try staggering the rotation of the motors on each plane same as if they were the only motors, that should eliminate any weirdness created by having one set in closer to center than the other. The opposing rotation will balance it all out on each plane and should make it stable yawing in either direction. You may have to do some wire swapping both on the motor/ESC and at the flight controller to get things sorted but it should resolve any imbalances.

Ken

+1 on this , having all the top props spinning the same way will cause issues with nice yaw, and also cause it to yaw noticably in forward flight (Y6's are also affected by this)

 

[Lanzar]

first off all alighn motor so they are not offset. just drill or remove the nuts with thread on one side and screw the engine holders with 4 screws. and be shure they are leveled. you dont need longer booms. makes no sence in going longer.

 

[Benjamin Rowland]

first off all alighn motor so they are not offset. just drill or remove the nuts with thread on one side and screw the engine holders with 4 screws. and be shure they are leveled. you dont need longer booms. makes no sence in going longer.

That was my original plan, but I ran into this problem ( see the picture ). The screw heads weren't accessible. My daughter was determined to get her foot in the picture.

 

[ChrisViperM]

Easiest would be that you take a very long screw (cut the head off) or a threaded rod and use flat nuts on top and bottom.....you should be able to hold the nuts with a spanner since they are pretty flat in that size.....a bit of fiddling, but should work. On one side of you could glue the nut with super glue if you like, but thread-lock on both sides should also be fine.


....and Happy Easter


Chris

 

[Lanzar]

That was my original plan, but I ran into this problem ( see the picture ). The screw heads weren't accessible. My daughter was determined to get her foot in the picture.

i know it can be done but you need some luck and some persuation to do it. There is one key that has the option in sliding inside. Or you need some spacers under motors, but then you need to cut some carbon to make it dubble thickness.