lml@lancaironline.net Mailing List Archive

Randy,

One option to reduce aileron stick forces is to add something similar to, but not exactly, a roll trim tab. It goes on the wing opposite the wing that has the trim tab. Instead of attaching the new tab to a trim servo, it is attached to the trailing edge of the wing, or hinge bearing block, via a fixed push rod. The length of the rod is adjustable so you can change how much the stick forces are reduced. The new tab with the fixed push rod moves opposite the direction of the aileron.

After reading my own description even I am confused. But, if you look at a Cessna Corvallis (or whatever it is called) it is standard equipment. One of the first things Cessna did to reduce the aileron stick forces when they purchased the Columbia line.

I have flown a before and after example of this mod on a Glastar and it is a noticeable improvement. I have no clue what the potential structural or aerodynamic downsides might be.

Ken Kellner

----- Original Message -----

From: John Hafen

To: lml@lancaironline.net

Sent: Monday, March 05, 2012 9:25 PM

Subject: Re: [LML] LNC2 - Harminization between pitch and roll

Randy: It's the same on my IVP. If I sneeze, I will gain or lose 200 feet without touching the stick. The aileron forces are so brutal that I don't turn at all. I just go around the block.

If I do need to turn, I use my knees to provide pressure assist. Works for left turns, not so much for right turns.

I don't notice it after a few hundred hours, but pilots new to the plane freak out.

Cheers,

John

On Mar 5, 2012, at 1:41 PM, Randy Hartman wrote:

To: All LNC2 drivers and anyone else that wants to weigh in on the subject,

Subject: Stick force harmony (or stick movement vs. control surface movement) between pitch and roll

My Lancair 360 (N360DE), which I have flown now for 450 hours, has an characteristic that I would like some input on from all you well-informed and intelligent LML readers and contributors.

The characteristic is: Very sensitive pitch axis that is not harmonized with the roll axis.

I have gotten used to the difference and frankly don't plan on changing anything about it unless someone out there has a good suggestion.

I have some questions:

1.       Is this typical of the LNC2?

2.       What kinds of things should I be concerned about in considering any changes to the linkage of the system?

3.       Has anyone made any changes and what were the results?

4.       Does anyone out there have any experience with using full pitch deflection - in any portion of flight? I imagine it might be needed in landing, full flaps, lower speeds - but I have not seen it.

It seems to me the way to make an increase in aileron sensitivity is to change the mechanical linkage geometry to effectively make the control surface move more degrees of rotation per degree of stick movement. This would (and could) be done but the resultant would be the stick not getting full deflection (as compared to now) in the cockpit when the aileron was at full deflection. This might not be a bad thing because right now the stick has to be jammed up against one or the other of your thighs in order to get the aileron to full deflection.

Ideally I would like to have less sensitivity in pitch, resulting in more stick deflection for the same pitch results as now - and less total stick deflection in roll, which should result in more roll sensitivity.

For clarification purposes - my horizontal stab and elevator are a one-off design of Chuck Brenner. Chuck was involved with part of the construction of this project prior to my involvement with it.

Randy Hartman

Cell (319) 360-9775