Odd (rudder?) Behavior?

[Nukemzzz]

So on our second test flight today I noticed something bugging me... 

set up for 130kt straight and level cruise when I turned left... no rudder was required to maintain coordinate..even at 30 degrees.  When turning right it seems a lot is required.  Seems to track straight in straight and level flight  

The PC system works now.  The autopilot is trying to work but it hunts constantly left to right trying to stabilize the track.  Altitude hold seems to be caput.  I also noted that with the PC engaged it takes some muscle to turn the yoke right, but the PC force isn’t noticeable when you turn the yoke to the left.  I don’t know if this is related to the strange rudder behavior.  Disengaging PC didn’t change the lack of rudder needed in the left turns.

What gives?  Do I have a rigging issue?  Is there something supposed to be linking rudder to aileron to auto coordinate and that something is broken for right turns?

Thanks in advance for your thoughts. Got 2 more hours in it today. So far so good, but finding new demons to chase...like a very stiff trim wheel at max nose up (jack screw needs overhaul maybe)  

 

[kortopates]

The 4 left turning tendencies:

 

https://www.boldmethod.com/learn-to-fly/aerodynamics/why-you-need-right-rudder-on-takeoff-to-stay-on-the-centerline/

 

Going relatively slow in full power climb, you might still need a bit of Right rudder turning left to keep coordinated!

 

Sent from my iPhone using Tapatalk

[DMM]

On 12/29/2020 at 11:33 PM, Nukemzzz said:

Is there something supposed to be linking rudder to aileron to auto coordinate and that something is broken for right turns?

On my 64E the rudder and ailerons are loosely connected with a rudder bungee located next to the pilot side brake master cylinder.  See #28 in pic.  Edit:  Correction I believe the interconnect spring is item 23 (bottom picture). 

Edited January 4, 2021 by DMM

[Prior owner]

I believe the 1966 has the rudder/aileron interconnect, and may also have the bungee. Aside from the basic flight controls  rigging possibly being incorrect, I have seen instances where the interconnect spring clamps had to be moved, per the Mooney manual procedure, in order to get the plane flying right. But basic rigging has to be checked first. The aircraft could presently be rigged to compensate for something being out of adjustment. That said, I don’t know that the bungee or interconnect system actually provides a perfect and/or equal amount of rudder in both left and right turns to compensate for adverse yaw even when it is rigged properly... 

[47U]

1 hour ago, PilotCoyote said:

But basic rigging has to be checked first.

Since your history with the aircraft is relatively short, I think PilotCoyote gives excellent advice.  Did you get enough flight time before the engine work began (almost a year ago?) to get a feel for how it flys?  We’re assuming that the engine mount and alignment is all good when the engine was rehung.   

Congrats on getting her back in the air.  You’ll get it all figured out, I’m sure.  Your sortie on 29 Dec looks like pure fun to me.

[Nukemzzz]

2 hours ago, 47U said:

Since your history with the aircraft is relatively short, I think PilotCoyote gives excellent advice.  Did you get enough flight time before the engine work began (almost a year ago?) to get a feel for how it flys?  We’re assuming that the engine mount and alignment is all good when the engine was rehung.   

Congrats on getting her back in the air.  You’ll get it all figured out, I’m sure.  Your sortie on 29 Dec looks like pure fun to me.

Haha, yeah, the NW and then SE leg was checking the Brittain autopilot. You see it swerving back and forth on the SE leg, that’s it not tracking so well...seems to overcompensate and then has to fix it and then overcompensates more. It’s over controlling...PID issue. Not sure what to do about that yet. 

the southern leg of loops was 45 and 65degree turns. That’s where I’m confused by not needing any rudder in a left turn and a bunch of rudder in a right turn. 

[Nukemzzz]

I’m kinda fishing for someone to say: “mines done that for years, my left rudder isn’t needed much.”  And then I’ll just carry on for now with flight training. If someone says this dangerous and why then I’ll consider grounding it again until we sort it. My CFI didn’t seem concerned. He was mostly concerned that maybe the Brittain system is giving us inputs that we aren’t asking for which could make stalls unsafe. 

[McMooney]

2 minutes ago, Nukemzzz said:

Haha, yeah, the NW and then SW leg was checking the Brittain autopilot. You see it swerving back and forth on the SW leg, that’s it not tracking so well...seems to overcompensate and then has to fix it and then overcompensates more. It’s over controlling...PID issue. Not sure what to do about that yet. 

the southern leg of loops was 45 and 65degree turns. That’s where I’m confused by not needing any rudder in a left turn and a bunch of rudder in a right turn. 

check your brittain for leaks,   Had the same symptoms due to a leaky servo.

[Nukemzzz]

3 minutes ago, McMooney said:

check your brittain for leaks,   Had the same symptoms due to a leaky servo.

Just did, and replaced 4 of the 6 boots. Maybe need to check again. Thanks. 

[Gary0747]

I have wondered several times in take off and climb why it seemed that I was using varying amounts of right rudder compared to previous flights.   Not sure all the factors that can cause this?  I have been thinking I needed to check the rigging of the servos and cable lengths on the rudder assist servos in the tail cone but I have not located the rigging info on those parts. 

[Yetti]

There is a bit of right rudder required especially on take off  P factor.   To do a left turn out on take off you don't push on the left pedal just release a bit on the right pedal.   Cute trick showed to me by the CFII.    I think I keep a bit of pressure on both pedals in cruise, probably a bit more on the right. It all just takes a subtle changes to fly the thing coordinated.

[Nukemzzz]

On 12/30/2020 at 8:31 PM, Yetti said:

There is a bit of right rudder required especially on take off  P factor.   To do a left turn out on take off you don't push on the left pedal just release a bit on the right pedal.   Cute trick showed to me by the CFII.    I think I keep a bit of pressure on both pedals in cruise, probably a bit more on the right. It all just takes a subtle changes to fly the thing coordinated.

On left base and final no left rudder is required. I’m relaxing on the right some, maybe neutral. But no left rudder in the left turn. This can’t be normal right?  Descending slow left turn...no left rudder. 

[Yetti]

Just now, Nukemzzz said:

On left base and final no left rudder is required. I’m relaxing on the right some, maybe neutral. But no left rudder in the left turn. This can’t be normal right?  Descending slow left turn...no left rudder. 

Whatever it takes to keep the ball coordinated.   Most everything on the mooney is very small input.   I normally fly thumb and finger.

[Nukemzzz]

So new potential piece of info...

While doing pattern work today we had a 5-6kt left crosswind. Takeoff was quite squirrelly each time. When we start to rotate, the second the plane leaves the ground it yaws to the left quickly. We go straight into a left crab...but man it snaps left fast and you have to hold it down and then jump up so the nose doesn’t stay the only wheel of the ground for long.  On one instance, I didn’t rotate fast enough and the plane turned hard left like it was wind vaning while still on the ground luckily I was fast enough to complete the rotation and lift off.  

Is this another symptom of what I’m discussing above?  I’m wondering if the left yaw bias is causing the nose wheel to not be aligned well with the rudder...this is something we actually adjusted per the manual while the plane was down because we rebuilt most of steering components. I seem to remember that it seemed to not be aligned well and we “fixed” it.  It behaves as if the plane needs more right rudder to fly straight under power headed down the runway and that is realized the moment the rudder has to control direction instead of the nose wheel. 

thoughts?

[Nukemzzz]

Maybe this is just me getting used to the plane. Maybe this is all normal. My CFI flew it by himself today however and he commented that takeoffs were tricky in this plane and flying seems second nature to him. He’s legit like a bird. Lol

[carusoam]

You have a few things going on at the same time...

1) a 200hp motor when rotated at lift off is going to require some right rudder during the rotation...

2) if your prior experience didn’t give you this affect, you may have had a lighter engine... or it wasn’t rotating as quickly...

There is a phun physics lab that demonstrates this squirrelly-ness... using a bike wheel and an office  charge...

3) A few knots of X -wind needs to be handled...  you will feel all kinds of drift, and weathervaning that changes with your speed...

4) Read up on the procedures... get practice...

5) Sounds like you may have a pair of springs that need to be reviewed... these are the rudder / aileron interconnects... if they are 50 years old... you might want to just buy new ones...  by the time you take them out to measure their skill... you might as well put the new ones in... skip the measuring...

6) Fly a lot... the more you fly, the more you will get a sense for the various affects of wind, temperature, and other climate issues... a broken spring will really stand out after a while...

PP thoughts only, not a mechanic...

Best regards,

-a-

[47U]

On 12/30/2020 at 6:28 AM, PilotCoyote said:

I believe the 1966 has the rudder/aileron interconnect, and may also have the bungee. Aside from the basic flight controls  rigging possibly being incorrect, I have seen instances where the interconnect spring clamps had to be moved, per the Mooney manual procedure, in order to get the plane flying right. But basic rigging has to be checked first. The aircraft could presently be rigged to compensate for something being out of adjustment. That said, I don’t know that the bungee or interconnect system actually provides a perfect and/or equal amount of rudder in both left and right turns to compensate for adverse yaw even when it is rigged properly... 

PC says it, basic rigging needs to be checked.

When the nose gear is straight (neutral, airplane tracks in a straight line with the tow bar), is the rudder also neutral?  If so, are the rudder pedals also aligned / even?

You can probably adjust this or that or the other and get it to fly straight, hands off.  But, there’s no substitute for starting at the beginning with a set of travel boards.

Keep reporting.  We’re all learning from your experience!

[Nukemzzz]

8 hours ago, 47U said:

PC says it, basic rigging needs to be checked.

When the nose gear is straight (neutral, airplane tracks in a straight line with the tow bar), is the rudder also neutral?  If so, are the rudder pedals also aligned / even?

You can probably adjust this or that or the other and get it to fly straight, hands off.  But, there’s no substitute for starting at the beginning with a set of travel boards.

Keep reporting.  We’re all learning from your experience!

I think I see a trip to Don Maxwell for this plane in the future just to be sure that it’s rigged right. I don’t believe my shop here has Mooney travel boards. Great shop, great guys, but not Mooney specialists. Rigging feels like I need a specialist or I need to become one myself.  Lol

[carusoam]

8 hours ago, Nukemzzz said:

I think I see a trip to Don Maxwell for this plane in the future just to be sure that it’s rigged right. I don’t believe my shop here has Mooney travel boards. Great shop, great guys, but not Mooney specialists. Rigging feels like I need a specialist or I need to become one myself.  Lol

It’s a two part problem... get it close with the boards, then... rig, fly, rig, fly... repeat...

So... taking it to Don makes a ton of sense... based on the amount of time required to go through the steps...

very little opportunity to learn the process... hard to get somebody else to pay for this...

Best regards,

-a-

[cliffy]

How does it fly with the PC/autopilot system off?

Make sure the AP AND the PC systems are off and unpowered (no vacuum to the PC system) and make another flight. 

You're grasping at too many variables at one time right now.

With all of that stuff unpowered and no vacuum to the PC fly and see how well it holds a straight and level heading. 

If it falls off quickly 1-4 seconds then you have a rigging problem

If it stays straight and level for 10 seconds or more look to see if your ailerons  are faired with the rear edge of the flaps. If one is way higher than the flap trailing edge you have rigging problem. If both are above the flap trailing edge its still a rigging problem 

[Nukemzzz]

8 hours ago, cliffy said:

How does it fly with the PC/autopilot system off?

Make sure the AP AND the PC systems are off and unpowered (no vacuum to the PC system) and make another flight. 

You're grasping at too many variables at one time right now.

With all of that stuff unpowered and no vacuum to the PC fly and see how well it holds a straight and level heading. 

If it falls off quickly 1-4 seconds then you have a rigging problem

If it stays straight and level for 10 seconds or more look to see if your ailerons  are faired with the rear edge of the flaps. If one is way higher than the flap trailing edge you have rigging problem. If both are above the flap trailing edge its still a rigging problem 

Last week I removed the PC button to get the system out of the way while I train landings and such. Seems to fly just fine straight and level, though it always needs a lot of nose up trim. takeoff trim is extremely close to trim needed for cruise and landing. Of course there is 500lbs in the two front seats. 

Strangely, when reviewing my videos I think I’m seeing a yaw oscillation.  Something I didn’t notice while flying but its in the video clips. I’ve not decided yet if it’s a real thing, just maybe a new clue. I’m not so worried about it because it clearly damped and dies down. But it looks like when the controls are disturbed the nose oscillates left to right 5-6 times before dying down. 

I think what’s going on here is I’m driving a vintage sports car with wings and things aren’t going to be perfect. I owned and drove a 1971 MG Midget in high school. It had some driving quirks like this as well. Lol

[cliffy]

Just a caution to run a real good W&B  with that much weight in the front seats

You might be fwd of the fwd limit 

[Nukemzzz]

1 hour ago, cliffy said:

Just a caution to run a real good W&B  with that much weight in the front seats

You might be fwd of the fwd limit 

Yeah. We are good. We weighed the plane last month and W&B is in, just barely, but in. I’m running with only 25gal. 

Actually the CG isn’t that far forward strangely. My empty CG is back a little. 

[carusoam]

Some people use the rudder pedals in flight...

having your feet on the pedals can dampen the oscillations that come with bumps in the road...

When cruising above the bumps...  slide the seats back for better WnB...

+1 for doing WnB calculations... 500LBs in the front seat will be very close to the front of the graph...

Add a few tools to the tool box in baggage area... throw an extra hat on the hat shelf too...

If you run out of trim in the traffic pattern, working on the balance is a common PP effort...

PP thoughts only not a CFI...

Best regards,

-a-