Stability in X-Plane

[Chris Ross]

I guess I just spat hthe dummy on the Buffalo crassh link

I have been flying a Ceesna 172 and a Beech staggerwing in X-Plane in the GAAR09
With both planes I find the biggest problem is trimming
I have never flown a Beech 17 but I flew about 35 hours in training in the 1960's in a C172
You had to trim to keep flying at the speed and climb rate that was required The only trim I rememember using was pitch the litlle wheel between the seats
Imn x-Plane If you take off an d trim for pitch and sit back tjhe Ac will turn to port and go out of control?
I guess as a newco mere to X-Plane which by the way I like I should post this as a query at an X-Plane forum but I am comfortable at this foru m and I am hoping it will as the beatles said come together in the end
I hope MS are listening
Chris

[Tom Goodrick]

I have an old version of X-Plane and flew it enough to find that it behaved normally with pitch trim. I only flew the Baron.

One of the very bad things about FS9 is that it assigns considerable lateral stability to any aircraft. I often reduce this when working on realistic FD but I don't remove it all together. I Real World flying, I always used pitch trim but that never meant I could take my hand off the wheel. There was a degree of lateral/directional stabilit. At cruise you could let go of the wheel and turn about to get something from the back seat. But you never did this below 1000 feet and never when climbing. Climbing introduces some torque disturbance to make the aircraft turn. This may be cranked up a bit in your setup of X-Plane but it is not unrealistic. Only when the autopilot is ON can you take your jhands from the wheel or stick.

[bgak011]

Chris, my Beech 18 and C-206 also does the same thing. I think you need to add an aileron trim gauge on the panel. Once you have the trim gauge added, then it is just a matter of cranking in 1 or 2 degrees of trim. Have you used the "Settings" / "Data Input and Output" to display various info about almost anything on the screen? Put a check mark in the fourth box, of Item 11, and it will show you the position of your flight controls. If you need help with this let me know.

Using the aileron trim allows me to take off with the wings level, on my Beech 18.
Coleman

[Tom Goodrick]

Is your load balanced? Most of my experience with RW flying in Cessna 150's and 172's was when I was the olny occupant. The planes were biased to turn left - toward my weight. There was no aileron trim. In FS9 I am guilty of making things easy by putting in a balanced load - two pilots of equal weight and two passengers of equal weight. The planes do fly straight when I take my hands off the wheel. Today I worked with unusual loads including unsymmetrical loads. When I took the Skylane off autopilot it was difficult to handle. That's just the way things are. The Staggerwing must be very tricky under similar conditions.

[bgak011]

Tom
I have not found a way to assign individual seats, in X-Plane, but your explanation is probably why the aircraft flies that way.

Chris
I did find this exerpt, in the manual, about tuning the aircraft. I have got a couple more flights to make in the " FS Economy " world, (to earn some more virtual dollars). When I have finished those, I will experiment with this info on the C-172.


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If the REAL plane is pulling to one side or the other, you bend the little trim tab on the aileron one way or another. This bending of the aileron trim tab counter-acts any imperfections in the shape of the airplane or dynamics of the propwash or mass-distribution inside the plane. Well, you can do exactly the same thing in X-Plane: Bend a trim tab a bit one way or the other to make the plane fly true. How do you do it? Still pretty easy. Exit X-Plane. Open Plane-Maker. Go to the 'File' menu and open the plane that is pulling left or right. Go to the 'Standard' menu and then to the 'Control Geometry' screen. Go to the 'Trim and Speed' tab. Go to the very RIGHT-HAND column of numbers in the top box of the screen: 'Trim Tab Adjust'. This is simply how much the trim tabs are bent on each axis. Top is elevator. Middle is aileron. Bottom is Rudder. (look on the left side of the screen). A value of 0.00 means the trim tab is not bent at all. A value of 1.00 means the tab is bent so far that the
control is FULLY-DEFLECTED by the trim tab (!) way too much I am sure. So, you want to
bend the trim tab A LITTLE BIT. Maybe 0.05 or at most 0.10. This would correspond to being enough to deflect the controls 5% or 10% due to the trim tab. Now, which WAY do you bend it? Positive or negative? Well, positive is up and right. So, if you want the plane to roll RIGHT a bit more (or STOP rolling left!), then enter a POSITIVE number for the aileron. Ditto that with rudder if you want the plane to pull RIGHT a bit more, and ditto that with elevator if you want the plane to pull UP a bit more. Tweak the trim tabs, save the plane, exit Plane-Maker, run X-Plane, go flying, and you should notice the plane pulls one way or another based on how you bent the trim tabs. Tune as needed to get the plane to fly as straight as you want.
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[bgak011]

I checked the C-172 trim tab setting and it was set at 0.005. I changed it to 0.006 and it made a huge difference. I can now lift off the runway, hands free, and it holds the wings level. It took several small adjustments to find this setting, but it works. You might know that I started adjusting it in the wrong direction and had to go the other way.
Coleman

[Chris Ross]

Thankyou Coleman and Tom
I had to reinstall Xplane because Vista told me the program had stopped working after updating to 9.30 beta
I have gone back to 9.22 non beta and it seems to be working better than ever
Coleman,I am using your tips to explore and I too find the C172 responds well to 1 click up(0.06) The staggerwing needed two (from 0.00 to 0.02)
Chris