lml@lancaironline.net Mailing List Archive

Randy,

1. Yes, this is characteristic of the LNC2s.

2. There is a proven, Lancair approved, mod that you can make.

3. Yep, several of us. Good results, a little more pitch stick force required...not quite so sensitive.

4. I use full aft stick on the initial portion of the takeoff roll on a soft field. Other than this...no. Even a full stall, soft field landing doesn’t require full elevator deflection (at least on my 320).

Your theory on improving the control harmony is exactly opposite of what you need to do. For the elevator, you want to increase stick FORCE required for a given elevator deflection, not stick MOVEMENT required. The way to do this is to shorten the arm on the elevator that the push rod is attached to. This reduces the stick’s mechanical advantage and requires a bit more force. It also reduces the limits of the stick travel in order to reach the full elevator limits (a good thing).

Concerning the ailerons, if you wanted to reduce the stick force for aileron movement, you’d need to increase stick travel (increase mechanical advantage). This is, alas, not a practical option. As you mentioned, full aileron travel already requires that the stick be pressed against your thigh. Make the elevator mod and leave the ailerons alone. I think that you’ll like the control harmony a little better.

As I recall, Lancair issued a bulletin about this mod 12 or 13 years ago. I don’t have the paper handy but I believe that the attach point for the push rod was moved 1 inch closer to the elevator. I’m pretty sure that Scott did this mod too and I know that he has the paperwork at his fingertips (he’s so damn organized).

If Scott or someone else doesn’t post the written mod, I’ll try to find it for you.

Bill Harrelson

N5ZQ 320 2,030 hrs

N6ZQ IV under construction

From: Randy Hartman

Sent: Monday, March 05, 2012 4:41 PM

To: lml@lancaironline.net

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

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