trpastor

Hey Guys, I have a 71" yak, weighs in about 9.5 or so lbs. Flys really well. Hovers easy kninfe edges are jut about perfect.

But in a harrier it rocks like mad. Is it nose heavy and I'm just able to hover a nose heavy plane well? The other thing I can think of is the fuel tank is about 4" in FRONT of the tube (and hence the CG). Could the fuel sloshing around be making it worse since it's not over the wing? I want to move it back anyway, since it's probably a totatlly different plane full of fuel vs. empty with it so far forward.

Thanks for any help
Tim

nmking09

My Feedback: (61)

Moving the CG usually helps. Changing elevator throw works too. Fuel doesn't cause it, or at least I have never seen it cause wing rock. Flip the plan inverted straight and level and see how much elevator you are holding. If you are holding a lot of down elevator to sustain level flight inverted, you most likely need to move the cg back a bit.

You might want to learn inverted harriers first, they are usually much more stable.

Good luck!!

JOHNS3D

My Feedback: (5)

move your CG a little bit back.

wind junkie

My Feedback: (1)

Sometimes there is nothing to do but get another plane. Wing planform, loading and vertical fin area and placement are the biggest factors.

In general, sweptback planforms are really bad for harriers (they rock like crazy). A light wingloading helps. Never go for a small heavily loaded ultimate biplane they're the worst.

Swept forward or straight LE wings are good == like the Edge 540.

As nmking09 said, try inverted. The vertical tail if too small or short gets cleaner air when pointed down and that often helps.

Ever see the formerly wildly popular Funtana 40 size plane in a harrier? crazy wing rocking. The 90 size was a little better, but still had some issues at some angles. Some planes have a sweet spot alpha angle that they will or WILL NOT harrier steadily. Vary your elevator and throttle so you can avoid that angle and this will help.

trpastor

good info! Thank you. I"ll mess around some more and see what I can do
Thanks
Tim

wind junkie

My Feedback: (1)

Oh, I forgot to mention sometimes spoilerons will work to tame wing rock. I had a plane a few years back that had a smallish wing which would wing rock like crazy but when I mixed 50% spoilerons with up elevator that did the trick. I did this for both inverted and up elevator. Aeilerons moved about 40 degrees total up or down and about 50 degrees up or down on elevator.

Spoilerons mean up elevator command gives up aeilerons for both (50% total throw). You might try that and see if it helps. Get ready for landing approches to drop a lot more than you had before. You might want to put it on a mix switch until you get used to it. I left it on full time on my plane cause it was a snappy little demon without it.