Uncontrollable yaw on takeoff

[dlrk]

I just got this aircraft. Whenever I try to takeoff (having first set the rudder trim to the green line), it yaws to the right uncontrollably, and winds up spinning out on the ground. If I do manage to get it in the air, it rolls to the left constantly. I've tried taking off with the trim centered, instead of at the TO line, and it doesn't seem to be much different. I've checked the calibration of my yoke and rudder pedals, and both are fine, and perform normally in other aircraft. I'm on X-Plane 11.32.

I also have to add, that it is very frustrating to troubleshoot this aircraft, given that it doesn't seem to be possible to save a panel state.

Edited March 31, 2019 by dlrk

[jfjoubert]

13 minutes ago, dlrk said:

I just got this aircraft. Whenever I try to takeoff (having first set the rudder trim to the green line), it yaws to the right uncontrollably, and winds up spinning out on the ground. If I do manage to get it in the air, it rolls to the left constantly. I've tried taking off with the trim centred, instead of at the TO line, and it doesn't seem to be much different. I've checked the calibration of my yoke and rudder pedals, and both are fine, and perform normally in other aircraft. I'm on X-Plane 11.32.

I also have to add, that it is very frustrating to troubleshoot this aircraft, given that it doesn't seem to be possible to save a panel state.

Hi, have a look at the topics below w.r.t ground handling whilst taking off and landing.

I also struggled a lot (to the point of giving up ) and the only way to overcome this is with a bit of practice. And making sure that your rudder is properly configured.
Start out with no wind and just practice some run-ups on a long runway.

You'll get the hang off it. 

 

[dlrk]

Is yawing to the right supposed to happen though? Shouldn't p-factor be pushing me to the left?

[Goran_M]

Could you post a screenshot of the panel just as you're taking off, and describing what is happening?  When someone says it's "uncontrollable", I'm immediately leaning towards a hardware calibration issue.

[dlrk]

Video:

https://www.dropbox.com/s/egn1tykt8pit3ax/TBM900_1.avi?dl=0

Screenshot:

https://www.dropbox.com/s/vj2jd98iim1ypul/TBM900_4.png?dl=0

It's definitely not calibration, I checked repeatedly.

[Goran_M]

That's definitely not normal, and not something I've seen.

Can you show me a screenshot of your controller curves?

[dlrk]

https://www.dropbox.com/sh/x7iy1qg48kwk4ac/AAC5XUNgWNV6h_x5v89WCRbCa?dl=0
 

There ya go. Screenshots of the curves for my yoke and pedals. Again, I double-checked the calibration. Is it possible I'm not handling the rudder right? Is there a way to have x-plane export a video with control inputs displayed?

Edited April 1, 2019 by dlrk

[Goran_M]

No, I think you have your sensitivity turned up.  Try these curve adjustments.  

[dlrk]

Alright, thanks. I'll give it a try tomorrow (it's 12:05 AM my time right now). Just wondering, why is this manual curve adjustment necessary? I'm used to FSX, and I've never had to get that much into the weeds with sensitivity.

[Goran_M]

It's due to the huge amounts of hardware out there.  Some hardware works with your current settings.  Could be the firmware.  Could be the actual hardware configuration settings (I have a Saitek X52, and it has a ton of customizable settings in it's own software).  It's all about personal preference.  It can be seen as somewhat of an inconvenience, but it's definitely there for a reason.

Edited April 1, 2019 by Goran_M

[dlrk]

Ok. Just so I understand though, pulling to the right is normal/expected, and it's over correction due to oversensitive controls that's the issue?

[Goran_M]

If it's pulling to the right as much as I saw in the video, it's likely you have too much right rudder trim.  Try centring it a little more.

The over correction...yes...I would strongly suspect is due to the over sensitive controls.  It will roll a bit to the left on take off, due to P Factor.

Just want to mention, I was watching a stream this morning with the TBM, and the streamer took off and landed very nicely.  That's why what I see in your video is very unusual.  If you like, I can link you to a VOD if he has one.

[Sims Smith]

Thanks for the screenshots. I followed the instruction on both threads, adjusted the sensitivity and finally was able to make 3 take off and landing without ending up in the ditch :-) .  I couldn't keep the aircraft centered but it was mostly under control. Do we need to trim AIL as well?

 

 

Edited April 1, 2019 by Sims Smith

[Goran_M]

For correcting take off p factor, use rudder trim. When in the cruise, use aileron trim. 

[Gregg Seipp]

I think the overcontrolling is made worse by the 'squishiness' (for lack of a better word) of the gear.  It delays corrections and then acts sort of like a spring to launch the airplane in the opposite direction (instead of responding immediately to the correction, the airplane tends to lean and then lurch as it steadies back...more like a van than a sports car).  I read an article about the TBM8/9s that said that the gear is 'quite firm', which makes sense with those gear doors hanging so close to the ground.  I also looked for any evidence of the aircraft leaning, even in the slightest, on tight turns on youtube...didn't see any.  So, perhaps there's an adjustment possible there.  Also, could be a benefit if the nosewheel steering at high speed had reduced authority some.  I know that ground steering, especially with crosswind, is tough in XPlane.  I hope it's on their radar to keep improving it.

[dlrk]

Goran,

It seems a bit better now, so maybe I just need practice. Am I correct in thinking that aileron is needed on the takeoff roll as well? To be honest, I didn't know, until now, that p-factor caused roll.

Also I have a couple G1000 questions, should I put that in a different thread?

[dlrk]

I definitely seem to be getting the hang of it, with some practice and sensitivity tweaking. But is it normal for very little to no rudder trim being required for a low weight? The green T/O mark is completely excessive, at least at a low weight (full tank, 188 pounds in left seat).

[jfjoubert]

2 hours ago, dlrk said:

I definitely seem to be getting the hang of it, with some practice and sensitivity tweaking. But is it normal for very little to no rudder trim being required for a low weight? The green T/O mark is completely excessive, at least at a low weight (full tank, 188 pounds in left seat).

Hi, yes it is normal... have a look at page 39 of the QuickStartGuide.pdf included with the plane.
It's under TAXI-OUT PROCEDURES - Verify trim settings.

[dlrk]

Is there a way to more precisely determine what the rudder trim should be?

[mrogers0547]

I also have a terrible time on takeoff roll; landing roll out as well but not so much as T.O. Could this be a nose wheel steering issue vs a rudder problem? Other X-Plane aircraft have the "toggle nose wheel steering" ability but this TBM does not. Just saying...

[dlrk]

I'm also finding that adding power gradually, rather than releasing brakes at 50% and immediately pushing to 90-100 helps a lot

[Goran_M]

3 hours ago, dlrk said:

I'm also finding that adding power gradually, rather than releasing brakes at 50% and immediately pushing to 90-100 helps a lot

Yes, definitely add power gradually, instead of slamming it full forward.  The real aircraft has a power lever that is restricted by some friction.

[Gregg Seipp]

11 hours ago, dlrk said:

Is there a way to more precisely determine what the rudder trim should be?

It doesn't matter that much.  Trim is used so that you don't have to use so much hand, or in this case, foot control.  If you don't have enough trim in then you just compensate by using more of your foot.  I've seen some TBM pilots say that they use a lot of "right foot to keep the airplane aligned."  During my PPL test the examiner took control of the airplane and added a bunch of up elevator trim and gave me the airplane back.  I had to push the yoke hard to hold the airplane in the right attitude.  So, you use trim so you can take manual pressure off the controls but if you didn't have it, you compensate...you make the plane do what you need it to do.

Edited April 2, 2019 by Gregg Seipp