Problem with Aircraft roll?

[Muskoka 104]

Not a real world pilot here, but lots of experience with large rc aircraft, so bare with me.

 

I'm having a tough time getting aircraft to fly level. I'm constantly having to adjust the ailerons, and that wouldn't be such a big deal I guess, but it seems like your always one click away from rolling left or right. It's as if the aircraft is teetering on a cylinder.

 

Roll left, give one click right aileron and your rolling right, give one click left aileron and your rolling left. There doesn't seem to be a point where the rolling stops, it's a constant one way or the other. How do you stop the teetering. Controls are set up fine, something in Planemaker perhaps? It's not banking, it's a roll on its axis.

[LAdamson 240]

I know what you mean. Some of these aircraft are too sensitive & trim is touchy. I find that I often attempt to trim more, than flying the real airplanes. With my Vans RV, I installed an aileron trim, but it's more for fuel & passenger imbalance. It's not something I was constantly fooling with, because the plane has much more positive stability in roll, than not. In fact, with the real plane, aileron is just a few slight adjustments to maintain course once and a while, and not a constant need to keep wings from falling off one side or the other.

 

P.S. --- The short low aspect ratio winged RV6 I speak of.................is a whole lot "touchier" than a sedately stable Cessna 172. Just a slight nudge on the stick will send it one way or the other. Yet, it settles level in that little valley, where you can feel the airflow keeping you level on both sides.

 

L.Adamson

[jcomm 5,890]

You can play around with the RoGs (Raddi of Gyration).

 

I tried a thread a few weaks ago, not exactly to deal with the same type of problem, but you can find some info there too:

 

http://forum.avsim.n...rcraft-in-xp10/

 

For your specific problem I'd use a bigger RoG for roll, but it's difficult to "guess" the right value, and then to make it adapt to the other two moments (expressed in X-Plane as raddi of gyration).

 

You can also use artificial stability, either by increasing the corresponding slider (moving it right) on the controller settings in X-Plane, or by editing using Plane Maker.

 

I am more worried with the fact that probably the abnormal torque roll that plagues all prop aircraft (non counter-rotating) in X-Plane10 will most probably not see any improvement because I am almost sure it would take a lot of work to be done in the core flight dynamics code... :-/, but that's an old story....

[Muskoka 104]

I only ask because I don't have this issue with my rc planes or helicopters and there a lot lighter than real aircraft. If there out of trim one or two clicks either way and your good to go. They don't constantly roll around on their axis.

[jcomm 5,890]

I only ask because I don't have this issue with my rc planes or helicopters and there a lot lighter than real aircraft. If there out of trim one or two clicks either way and your good to go. They don't constantly roll around on their axis.

 

I know my friend :-/.... I feel your pain too.... it's like... a PITA... when everything is looking so nice, scenery progressing so fine, the 64 bit thing, etc... but then... a prop aircraft can't be flown realistically, unless you tweak through artificial stability - something I am sure Adamson's RV-6 is not equipped with...

[LAdamson 240]

I only ask because I don't have this issue with my rc planes or helicopters and there a lot lighter than real aircraft. If there out of trim one or two clicks either way and your good to go. They don't constantly roll around on their axis.

 

For many years, I also flew RC aircraft & helicopters......including light ones, heavy wing loaded ones, & quarter scale. As you said, they trim out too.

Full size is much the same.

[Walt90 0]

........... which raises the question, how can flight schools and simulator companies use XP for training if the aircraft flight dynamics are unrealistic. Do they have something we don't?

[jcomm 5,890]

........... which raises the question, how can flight schools and simulator companies use XP for training if the aircraft flight dynamics are unrealistic. Do they have something we don't?

 

Just like some use MSFS-based FNPTs, ELITE, ASA On-Top, ESP Protrainer, etc...

Not all use FRASCA, ALSIM, THALES, FSI, etc...

[Janov 2,383]

I have had good success in some other thread with a video proof of what X-Plane actually does and what it doesn´t - it was about the required rudder on takeoff. Unfortunately the person claiming that insane amounts of right rudder are needed on takeoff in XP has chosen not to participate in the discussion anymore...

 

So here is another video about trimming an aircraft in XP10 for straight and level hands-off flight.

 

Without getting into a deeper discussion about static and dynamic stability, here is a shot of me flying the default King Air - hands off, NO artificial stability. I added data display of flight-surface and trim position, also pitch and roll angles.

 

http://youtu.be/tKbLsIBuXPI

 

I´d say thats pretty much straight and level.

 

Hint for successful trimming: Use the trim controls in the airplane (grab and hold) instead of joystick buttons when fine-tuning the trim. They can be used to make much smaller trim adjustments. Also remember that the rudder is a finer blade when it comes to cutting it right. So first try to get really close with the aileron trim, then use the rudder.

 

Any change in airspeed, engine power etc. will probably upset your trim again.

 

I agree with the statement that the trim controls are too coarse for tuning the trim with joystick button during cruise speeds. Unfortunately there is no way to replicate the trim knob in a GA aircraft where you can either twist it really quick one or two turns while slow or just cant it a few degrees while at cruising speeds.

If you find your trim with the joystick buttons too coarse, you can change that sensitivity in plane-maker. Maybe also try to use a keyboard key-command instead, haven´t tried that, though. Remember that perfecting the sensitivity for cruise speeds will probably not be a good idea because trim then moves too slow at approach speeds. But it´s worth an experiment. The 737 has two different trim speeds, a faster one when flaps are extended to help with this problem.

 

Also remember that an airplane at 0 bank has very little stability at that very moment. The "desire" to level the wings gets stronger with the amount of bank...

 

I agree with L.Adamsons statement about trimming more when flying a simulator - I think the lack of sensory feedback is making accurate trimming more hard - so you have to chase the effects until trim is satisfactory.

 

About the flightschools using X-Plane - it is not really desirable to train students in IFR procedures with an airplane that will reliably go straight and level. You want your students to continuously "fly" the plane while solving the problems of IFR navigation with the remainder of their brainpower.

When we train in the LEVEL-D simulators our instructors will always set at least a small amount of turbulence, otherwise the plane behaves too predictable and presents an unrealistically simple training environment.

 

Jan

[Muskoka 104]

I think you have a point Jan that I need to test. It seems all control surfaces are too coarse "strong" when using the rockers or switches on my Saitek yoke for control surfaces in Xplane, I do have Saitek pedals for rudder control and they are fine, maybe a bit touchy.

 

Now, no body take this the wrong way, I don't have the same issue in FSX. I want to be able to adjust my aircraft in flight like I can in FSX, using my yoke for what it was intended. Using the keyboard to adjust control surfaces is not an option, I'm trying to get rid of my need for the keyboard all together.

 

What am I looking for in Planemaker to make the adjustments you speak of, I will play with it and see what I can do.

[tkyler 88]

There is a setting in plane-maker where you set the "time to trim from zero trim to full trim". (Menu "Standard > Control Geometry > Trim and Speed tab.....center column of numbers, "elevator trim full deflection time"). The bigger this number, the smaller the trim increment per second and you can fine tune your trim this way.

 

Another thing you can do....is look under your weather environment tab and look at the thermal climb rate. I think XP defaults this to 500 and IMO, it's about the most unrealistic aspect of XP...atificially introducing turbulence and upsetting the plane. Setting this value to zero is darn near magic IMO. With that set to zero....a decent RoG setting in PM and fine-grained control over the trim, you can get your trim behavior a lot more natural.

 

Tom Kyler

Laminar / IXEG

[Muskoka 104]

Thanks Tom, will get to it and report back.

[Muskoka 104]

Well, found the settings in Planemaker just fine. I have been using the default Baron in 64bit to test and play around. Before I was about to test the suggestions Tom made I thought I would go outside and have a look at the ailerons before flight.

 

You can see in the screen shots the amount of deflection that is there, and these are at the center position as fas as the controls are concerned. I'm sure this isn't helping at all. How do I go about zeroing out the aileron deflection before I try and test the new settings. In other words, zero, wasn't zero, to begin with. I know how to adjust it on my rc aircraft, not sure what I need to do here. :huh:

 

 

 

[Muskoka 104]

I really think it's a lost cause. I did make the adjustments Tom suggested and the throws were reduced but the Baron still rolls back and forth. When I fly my rc stuff for the most part the ailerons are neutral when I take off. If they need adjusting I can deal with it when airborne. Is that not the way real aircraft behave?

 

If I take off in the default Baron with ailerons neutral, as soon as it's off the ground it wants to roll hard to the left, why is that, torque roll, way too much if it is? I couldn't fly my rc planes if they behaved like that. It would take about 2-3 seconds to flip the Baron over if I wasn't hard on the yoke. So I give a few clicks right aileron and it comes to center and keeps going right. Give one click left aileron and it wants to go left, get the picture? It does not "seem" realistic at all, again I'm not a real pilot but I do fly planes with 5' wing spans and they don't fly like this, constant rolling back and forth that you can't stop with a bit of trim.

 

Goran, if you read this I just tested with the Duchess and at least I could get it trimmed and sit back for 30-45 seconds without it starting to move, or wanting to roll over. It would eventually start to move but it felt more like what I imagine flight to be. I wasn't constantly on the yoke or trim buttons. I did these tests with zero weather.

[jcomm 5,890]

Torque Roll - way too much and / or not properly compensated by other prop effects... Probably other factors too, I don't really know anymore... :-( Spoils the joy of flying an otherwise very beautiful model in X-Plane10...

If I take off in the default Baron with ailerons neutral, as soon as it's off the ground it wants to roll hard to the left, why is that, torque roll, way too much if it is?