Stick Shake

[cdarza]

How solid are your sticks.    (people with dirty minds go away haha).   This minimal shake doesn't bother me and barely noticeable however just for comparison is this the norm or are most rock solid.  

[WmInce]

Was the autopilot coupled in the video? If the gain is set too high in the autopilot pitch axis, it can cause the pitch servo to become “twitchy,” which can be felt as control feedback (pitch axis) of the control stick.

Or . . . You may be experiencing a little stabilator flutter.

Was that at normal cruise speed, during straight and level flight?

[sandpiper]

I bought my CTSW new in 2007. It has always had the notorious "stick bump" in cruise. At first I was concerned and flew a couple of other identical airframes. They were all the same. I have no autopilot so that has nothing to do with it. 

Irritating but normal. If anyone has a fix to eliminate or tone it down I would be interested. 

[Anticept]

Is the stick shaking from slop or can you feel it when you put a very slight pressure on it?

[cdarza]

The stick shake was at cruise speed roughly 105kts ias straight and level,   AutoPilot OFF,     I was not holding the stick to show how much it moves by itself.   When holding stick it does tone it down but not much.    Then again,   it is really not that noticeable,   when your up there and everything is so nice and smooth you sometimes notice these little things that normally are ignored.     

[Roger Lee]

Normal for many.

Now the first mystery is solved are we going back to the second stick shake?  Is that flying left seat or right seat? 

 

p.s.

You brought it up. LOL

[Tom Baker]

The stick shake comes from the laminar airflow over the stabilator un-attaching, then re- attaching. This was confirmed by Flight Design in the full scale wind tunnel test. The cause was how the airflow comes off the fuselage at the flap to fuselage junction. They made design changes to the CTLS to fix the problem. It is much better, but still does it a little.

It is only noticeable in nice smoot air.

[sandpiper]

On later airplanes FD "semi" fixed the problem with a thin vertical piece of material at the edge of the fuselage next to the flap. I don't know what else they may have done. Could this constant shaking have caused the stabilator attach bracket crack recently noted?

I wonder if the same could be done to the CTSW? E-LSA of course. 

[WmInce]

1 hour ago, Tom Baker said:

The stick shake comes from the laminar airflow over the stabilator un-attaching, then re- attaching. This was confirmed by Flight Design in the full scale wind tunnel test. The cause was how the airflow comes off the fuselage at the flap to fuselage junction. They made design changes to the CTLS to fix the problem. It is much better, but still does it a little.

It is only noticeable in nice smoot air.

Tom,

I am not doubting you, but any document source for that? If something was published by FD, I’d like to read up on it.

[cdarza]

7 hours ago, Roger Lee said:

Normal for many.

Now the first mystery is solved are we going back to the second stick shake?  Is that flying left seat or right seat? 

 

LOL

[cdarza]

4 hours ago, sandpiper said:

Could this constant shaking have caused the stabilator attach bracket crack recently noted?

 

I will edit my post on this re possible stress marks.    What I thought might be possible stress marks turned out to be just the paint (or at least it seems that way.)  I sanded down the area and it is now smooth with no signs of any marks on the metal.    I still find it strange how the marks or paint scratches appeared in that particular area.    Note the original post with a actual noticeable crack was not mine.  That one surely needed welding. or replacement. 

 

[Tom Baker]

9 hours ago, sandpiper said:

On later airplanes FD "semi" fixed the problem with a thin vertical piece of material at the edge of the fuselage next to the flap. I don't know what else they may have done. Could this constant shaking have caused the stabilator attach bracket crack recently noted?

I wonder if the same could be done to the CTSW? E-LSA of course. 

Beyond the plate the fuselge is more square on the CTLS in this area.

[Tom Baker]

9 hours ago, WmInce said:

Tom,

I am not doubting you, but any document source for that? If something was published by FD, I’d like to read up on it.

Bill, nothing in writing. It was something I picked up while working the booth at either Sebring or Oshkosh. I was in the booth at Sebring for 3 or 4 years starting 2008. I helped in the booth at Oshkosh 2008, until a few years ago when they didn't have a display. Over the years I ask a lot of questions from the people with the answers.

[WmInce]

1 hour ago, Tom Baker said:

Bill, nothing in writing. It was something I picked up while working the booth at either Sebring or Oshkosh. I was in the booth at Sebring for 3 or 4 years starting 2008. I helped in the booth at Oshkosh 2008, until a few years ago when they didn't have a display. Over the years I ask a lot of questions from the people with the answers.

Okay . . . thank you.