Wing rock

[emtp275]

Ok I have an Issue with my 88 pilot extra and wing rock, After today at the field I plan to go over a few things one Lateral balance the other is to make sure my elevators are matched perfect. This plane loves to start rocking in harrier. I need to figure out if its in my set up or if i should just let the plane go? I do not have this issue in any other airframe IE 91 Yak, 89 slick, 104 Slick please Help LOL. This is one of the best looking planes around and I wish I could get it to fly half as good as it looks

 

[Terryscustom]

Well, you are suffering from one of the things that I strongly disagree with that Pilot does as a design characteristic........LOW ASS STAB!! They do this to try to tune out coupling in knife edge.
Most planes with a normal stab location you make up for wing rock but adding a little more elevator and use the throttle to adjust for elevation (fully stalling the wing). With the super low stabs they use combined with light wing loading you end up with a wing that is balancing on the brink of flying and stalling......but if you add more elevator it is less effective because the elevator and stab placed below the wing (in full stall) is in really dirty air below the wing. Low stab works great when you are flying but for 3D it's often not a good solution.

Sorry, all I can say is I know of at least two people that have replaced the stabs on pilot planes, do the normally required KE mixing every other ARF requires in your transmitter and the planes fly better stalled. The larger planes are less effected but the 50cc is on the small size to use that type of stab placement.

 

[emtp275]

Well, you are suffering from one of the things that I strongly disagree with that Pilot does as a design characteristic........LOW ASS STAB!! They do this to try to tune out coupling in knife edge.
Most planes with a normal stab location you make up for wing rock but adding a little more elevator and use the throttle to adjust for elevation (fully stalling the wing). With the super low stabs they use combined with light wing loading you end up with a wing that is balancing on the brink of flying and stalling......but if you add more elevator it is less effective because the elevator and stab placed below the wing (in full stall) is in really dirty air below the wing. Low stab works great when you are flying but for 3D it's often not a good solution.

Sorry, all I can say is I know of at least two people that have replaced the stabs on pilot planes, do the normally required KE mixing every other ARF requires in your transmitter and the planes fly better stalled. The larger planes are less effected but the 50cc is on the small size to use that type of stab placement.

Well thanks that is at least an answer before I chase my tail trying to fix it

 

[David Shriver]

I agree with Terry on the wing fowling the airflow over the tail. There are a couple of things you can try though. Try moving the CG some. A bit more tail heavy might help. If that doesn't help try shifting the CG a bit towards the nose. My 78" EF Extra will rock if I don't hold the nose high enough. So try a bit higher attitude for your nose. If none of that helps try a bit of spoileron. Raising both ailerons will make the wing stall faster.

 

[pawnshopmike]

Trade it for an Edge. Problem solved.

 

[Pistolera]

Trade it for an Edge. Problem solved.

Hah!

Well....the spoileron trick that David mentioned is certainly the cheapest solution, and usually works. Set the mix up so the up ailerons (both sides, of course) are mixed in with up elevator. Put it on a switch as you don't want it on all the time.

You'll have to experiment with how much up aileron you need. Remember, it's dumping lift as they raise up.

 

[babathehutt]

I don't like the spoiler on method as you have to turn it off to go inverted or fly normally. The better thing to do is either get the wing fully stalled or attached. Maybe try SFGs or vortex generators.

 

[Bunky.F.Knuckle]

Get the nose higher, or add about 15% up aileron to kill the lift. Or shift your CG aft a little.

 

[Bunky.F.Knuckle]

Hah!

Well....the spoileron trick that David mentioned is certainly the cheapest solution, and usually works. Set the mix up so the up ailerons (both sides, of course) are mixed in with up elevator. Put it on a switch as you don't want it on all the time.

You'll have to experiment with how much up aileron you need. Remember, it's dumping lift as they raise up.

Funny thing happened a few weeks ago while out at my local field. Got into a discussion with a full scale pilot, about lift. He was bound and determined to disagree with me about how each side of the wing works, in regards to lift. He, of course, is an RC pilot too. He lost the covering on the top side of his Sweet Stick wing, while flying inverted. Said he was losing lift when he rolled over to upright. I said no way. I also said, that when you are upright, the bottom of the wing generates lift, the top used gravity, to hold the airplane down. He flat told me I was wrong. Told him that he needed to continue to do what he does, and I will do what I do and that is have fun!

Back to our regularly scheduled program.

 

[David Shriver]

Are you using SFGs? My extra is much much more stable in high alpha with them than without them. It doesn't snap as cleanly and rolls aren't as nice, but high alpha is way better.