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Old Aug 08, 2012, 04:09 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
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Originally Posted by erkq View Post
I've been mostly lurking here. Looks like a nice plane. But I do have an AJ Slick 51 that doesn't rock like that for sure! Would a gyro on the ailerons be a cheap fix? The rocking is slow enough a gyro could easily keep up. I know it is usually considered cheating but this plane has potential and that rock looks like it could be damped out pretty easily.
Yeah, I tried a gyro, a full 3-axis job. It did pretty much prevent the rock but it couldn't catch it when the wing dropped, leading to my crash. I'm not seeing the drop now so maybe the gyro would do the job but I'm going to try to figure out the cause if i can rather than cover it up with a gyro.

As Chop Stix says; the gyro would also make certain manoeuvres impossible so it needs to be switchable, which is a bit of a pain.
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Old Aug 08, 2012, 04:25 AM
Grumpy old git.. Who me?
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Originally Posted by NJSwede View Post
Wow! That was pretty impressive! However, the mystery remains: What's causing the wing rock???
While flying the Slick this last time and watching the video i got to thinking that the wing rock looks a bit like 'Dutch roll' The cure for Dutch roll is usually to make the vertical stab larger. The vertical stab/rudder on the HK Slick actually looks like it plenty big enough as it is, but maybe it's getting blanked by the fuselage/wing and horizontal stab when the plane is in high alpha?

So my next experiment will be to tape a foam extension onto the rudder to increase the area and see if that makes any difference. if it does it would be easy enough to build a larger rudder.
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Old Aug 08, 2012, 08:11 AM
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Burke, VA
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I just had a weird thought, I wonder if a spoiler made of triangular stock on the LE of the right wing would help. This would be similiar to the ones used on some full sized planes. On full sized planes this helps with stalling and may do the same on an rc plane. I would give this a try but none of the planes I have exhibit these problems, they either are crashed and trashed or I just avoid buying them based on info gleaned from RCG.
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Old Aug 08, 2012, 08:24 AM
how'd I do that....oh
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South Africa, GP, Pretoria
Joined May 2011
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I think we have discussed that way back in the thread where Steve said he thought of that.but they won't really have any effect poststall.remember in 3d we want the wing to stall...especially in harrier so they won't help.those were made to delay stall on a plane,so will be quite irrelevant here.Well that's if I understand aerodynamics right
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Old Aug 08, 2012, 09:02 AM
doh!
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United States, AR, Little Rock
Joined May 2006
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Originally Posted by JetPlaneFlyer View Post
ok here's the video, all comments welcome other than "your flying sucks".. I've got feelings!
Have you tried harriers with a higher angle of attack? Get the nose up to 45-50 degrees instead of the lower ~30-40 it was at and what does it do?

Video made me dizzy by the way... I guess I'm too used to flying at organized fields and keeping the plane in front of me. It seems very strange to fly in a big circle with me in the center.
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Old Aug 08, 2012, 10:03 AM
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Australia, SA
Joined Aug 2009
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Does anyone have photos comparing the rib profiles of the HK slick and the 3DHS one? Or say comparing to an EF EXP airfoil?
How different are they really?

Maybe shots of the root and tip airfoils? Because someone said that the HK airfoil gets fatter towards the tips, no?
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Old Aug 08, 2012, 10:28 AM
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Quote:
Originally Posted by chop stiX View Post
I think we have discussed that way back in the thread where Steve said he thought of that.but they won't really have any effect poststall.remember in 3d we want the wing to stall...especially in harrier so they won't help.those were made to delay stall on a plane,so will be quite irrelevant here.Well that's if I understand aerodynamics right
Oh yeah, now that you mention it I do recall something to that effect. But isn't the problem a tip stall, which is the main problem aside from wing rock? Maybe this would at least eliminate that disastrous characteristic even if it doesn't improve the 3D aspect of flying. That would still be an improvement worth exploring. If it didn't help it would be easy enough to remove the spoiler.
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Old Aug 08, 2012, 11:11 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
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Quote:
Originally Posted by ryan_m View Post
Have you tried harriers with a higher angle of attack? Get the nose up to 45-50 degrees instead of the lower ~30-40 it was at and what does it do?
Generally the higher the AoA the worse the rock.. it was at 45 deg and more in patches on the vid but it gets too unstable for comfort (for me)
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Old Aug 08, 2012, 11:19 AM
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United States, NJ, Mendham Township
Joined Jul 2011
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Quote:
Originally Posted by JetPlaneFlyer View Post
Generally the higher the AoA the worse the rock.. it was at 45 deg and more in patches on the vid but it gets too unstable for comfort (for me)
That's evidence against the problem being caused by partial stalling of the wing, since the higher the AoA, the higher the probability that the entire wing is stalled. Right?

I love a good mystery!
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Old Aug 08, 2012, 11:19 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
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So I taped on a depron foam extension to the rudder to create more vertical stab area:


It sure isn't pretty..... Any bets on if it cured the wing rock? You have until the video uploads to make your predictions.

Steve
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Old Aug 08, 2012, 11:21 AM
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United States, NJ, Mendham Township
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Originally Posted by JetPlaneFlyer View Post
It sure isn't pretty..... Any bets on if it cured the wing rock? You have until the video uploads to make your predictions.
It's a "no" from me, Steve!
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Old Aug 08, 2012, 11:25 AM
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United States, CA, Sebastopol
Joined Dec 2010
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Originally Posted by chop stiX View Post
hahahahahhahaha.NO!!!!!and Steve has found out the hard way that gyro only makes it worse and will surely cause a crash.think what that darn thing will want to do in KE spin or a blender or poptop.......I don't want to go into the whole gyro thing again and offend people by my thoughts on using a gyro in a plane....so I'll zip ithehehehe
Really... that's uncalled for. I can see why you can't discuss "the whole gyro thing" without offending people. Offending people just comes naturally I guess. You jumped down my throat with no provocation a while back. You apologized. I'm glad I never accepted 'cuz here you are again.

BTW, my fully AS3X-ized UMX Sbach can do both poptops and blenders. I don't think there's enough mass to swing into a KE spin. But having the wing oriented vertically should pose no problem for a gyro.

However I can see a gyro leading to a crash. It masks stuff until it's too late. Happens when hovering a Beast 3D a lot. Once it breaks out it's really all over... there's nothing left to recover.
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Old Aug 08, 2012, 11:36 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
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Originally Posted by NJSwede View Post
It's a "no" from me, Steve!
ok one for 'no'.. anyone else want to have a punt? Video is 15% uploaded.. be quick
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Old Aug 08, 2012, 11:38 AM
Santi
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United States, MO, Clayton
Joined Nov 2003
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Quote:
Originally Posted by JetPlaneFlyer View Post
So I taped on a depron foam extension to the rudder to create more vertical stab area:


It sure isn't pretty..... Any bets on if it cured the wing rock? You have until the video uploads to make your predictions.

Steve
I guess no... I did however find a solution to the problem at hand.. I Sold the HK and bought 2 AJ slicks!
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Old Aug 08, 2012, 11:42 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
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Originally Posted by UCDme3D View Post
I guess no... I did however find a solution to the problem at hand.. I Sold the HK and bought 2 AJ slicks!



ok.. two for 'no'... And selling the HK Slick doesnt count as a solution
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