I have a 2.6m Yak 55sp from CARF that wing rocks pretty regularly when in an up right harrier. I can counter it with coordinated rudder and elevator but it sure would be nice to minimize.

Anyone with experience with setup on this airframe to help reduce the tendency?

Originally Posted by mrc100

I have a 2.6m Yak 55sp from CARF that wing rocks pretty regularly when in an up right harrier. I can counter it with coordinated rudder and elevator but it sure would be nice to minimize.

Anyone with experience with setup on this airframe to help reduce the tendency?

I like just a tick more tail weight to get 3D maneuvers locked in. Also, angle of attack verses correct throttle management will eliminate a lot of the wing rock. In a harrier, the ideal scenario is to get both wings equally displacing the same amount of air and creating lift of both wings. Steepen your angle of attack, a click or so higher throttle or "blipping" your throttle will also help. What causes wing rock is a pendulum effect of intermittently each wing "stalls" while the other is generating lift. then the stalled wing will get lift while the opposing wing stalls. Many guys have their own technic. These are what works best for me.

The plane is currently a little tail heavy. I'm going to try mixing in a little spoileron on a switch to try when on 3D rates. I have foam planes that lock right in and I realize that a 35 percent model will not be nearly as steady from wing loading alone but I'm spending so much time countering the rocking that steering and turning is over load. We'll see. In theory the spoileron should help both wings stall quicker and perhaps at a shallower AoA. As it is now if I force the angle of attack I literally lose forward momentum. Probably 65 degrees and at that angle the wings stop rocking and rolling.

I flew that airframe for 6 years. I didn't care for it when it was tail heavy or neutral. It always behaved better when slightly nose heavy. The plane had 4 different engines on it and I always had to get the cg back to slightly nose heavy. Had a GP123 on it for awhile and had to put a DA100L on because it was too neutral feeling.

With that being said it is not that great of a 3D airframe because you are limited by the aileron throw due to method of hinging. After fighting that I sold it and bought another EF 300. Much more capable. It was a great IMAC plane but not nearly as capable in 3D.

Originally Posted by jon595

I flew that airframe for 6 years. I didn't care for it when it was tail heavy or neutral. It always behaved better when slightly nose heavy. The plane had 4 different engines on it and I always had to get the cg back to slightly nose heavy. Had a GP123 on it for awhile and had to put a DA100L on because it was too neutral feeling.

With that being said it is not that great of a 3D airframe because you are limited by the aileron throw due to method of hinging. After fighting that I sold it and bought another EF 300. Much more capable. It was a great IMAC plane but not nearly as capable in 3D.

Thank you for the feedback. I was kind of wondering what would happen if I tried nose heavy but that is so contrary to what most say is needed for 3D. Actually had the plane for 11 years so but haven't been flying it for the last couple, maybe three years. Great airplane but it does like to wing rock and I really need to tame that to get closer the ground. Any chance if you recall how it balanced at the wing tube opening without wings? I have a DA100 on it with KS pipes.

Did you ever try spoilerons?

Never tried spoilerons. It was a handful in harrier and the pucker factor was very high. I understand what you are going through. Even after getting it as light as possible it did not change its flight characteristics. So I decided to move on.

I never tried to balance it without the wings on.

I do not like a plane that is neutral because on a slow speed harrier roll the plane wil want to go vertical on its own. I like to control that with the elevator input. Too nose heavy and it wont pitch up enough. Would be easier to show you than explain it. I tune all my planes the same way.

And a tail heavy plane also looses rudder authority in my experience.

I really appreciate the feedback. Thank you.....

I would also make sure the lateral balance is correct.

Spoilerons helped my CARF, it doesn't take much spoileron.

You might also try "burping" the throttle up and down, really extend the throttle curve around that magic lock in point.

Maybe try a different prop.

Once you get the airflow perfect over the wing root and tail the plane will lock in.

good luck!
Jeff

Originally Posted by jon595

And a tail heavy plane also looses rudder authority in my experience.

??? Looses authority???

Try a hammerhead with a tail heavy plane.

Originally Posted by jon595

Try a hammerhead with a tail heavy plane.

Granted, too tail heavy does result in less "ability" to perform certain maneuvers well. Especially a hammerhead. However that is not the same thing as "authority". Too tail heavy results in tail sensitivity being heightened. Plus very poor landing characteristics. I however have "never" seen a tick or tad or whatever I referred to, more tail weight... (my original comment) result in loss of rudder authority or lack of ability to do hammerheads!

Neutrally balanced planes fly well. Some airframes require less or more neutral balance. Nose heavy planes penetrate well and landings are nice. Sure as the sun rises in the east, you'll never get a nose heavy plane to 3D really well.

Airplane setup is all personal preference. If you would rather fly a plane that isn't locked in thats on you. For me a plane that has a forward of neutral cg gives me the best response. And I can 3D it all day long with no surprises. Again this is how I prefer to fly.