Jump to content

Another rigging question ...


Recommended Posts

Hello All,

 

During annual in July of last year the flaps on my '68 C were adjusted. They hadn't been extending as far as the should, and when retracted they were a bit "high" so that on the starboard side the corner of the inboard trailing edge contacted the fairing and rubbed a small hole in it.

Now, with the yoke centred the trailing edges of the flaps and ailerons are perfectly in line, but the aileron counterweights are sitting about 1/2" high of the wing surface on each side.

It seems to me that I must be losing some cruise speed, both from the drag of the counterweights sticking up in the wind and from the bit of extra camber in the wing. The plane flights pretty straight - verrrry slow left turn when trimmed in cruise with PC disconnected. I know tinkering with rigging can open a can of worms, so I'd like to ask the Mooney spacers who have faced this situation - is it worth adjusting all the trailing edges up so the counterweights lie flush? Might have to bend the flap to fuselage fairing up a tiny bit - otherwise the same number of turns would be required on each side to make the adjustment.

 

Dave

1968 M20C

C-GAVX

 

 

Sent from my iPhone using Tapatalk

Link to comment
Share on other sites

26 minutes ago, 170driver said:

 

Hello All,

 

During annual in July of last year the flaps on my '68 C were adjusted. They hadn't been extending as far as the should, and when retracted they were a bit "high" so that on the starboard side the corner of the inboard trailing edge contacted the fairing and rubbed a small hole in it.

Now, with the yoke centred the trailing edges of the flaps and ailerons are perfectly in line, but the aileron counterweights are sitting about 1/2" high of the wing surface on each side.

It seems to me that I must be losing some cruise speed, both from the drag of the counterweights sticking up in the wind and from the bit of extra camber in the wing. The plane flights pretty straight - verrrry slow left turn when trimmed in cruise with PC disconnected. I know tinkering with rigging can open a can of worms, so I'd like to ask the Mooney spacers who have faced this situation - is it worth adjusting all the trailing edges up so the counterweights lie flush? Might have to bend the flap to fuselage fairing up a tiny bit - otherwise the same number of turns would be required on each side to make the adjustment.

 

Dave

1968 M20C

C-GAVX

 

 

Sent from my iPhone using Tapatalk

 

The aileron mass balance should be flush with the notch in the wing tip in cruise flight, the flaps should be even with them as well.

The manual allows for drooping both down maximum of 2 degrees. The amount depends on how much free play there is in the control system.

Clarence

Link to comment
Share on other sites

You need to pull both ailerons up at the same time to remove any slack in the system to see where they sit when "loaded" in flight. Static sitting they will always droop a little.  To rig then you need to start at Point 0 in the MM and work your way out to the wing tips. 

  • Like 1
Link to comment
Share on other sites

The easiest way to adjust the aileron position is to loosen the jamb nut on the outboard rod end of the long tube that runs from the center link to the bell crank in the wings. Then remove the bolt between the tube and center link. 

Now you can easily rotate the whole tube 1/2 turn at a time. Much easier than trying to adjust anything at the bell crank.

As Cliffy says you need to adjust both the same. If you don't you won't end up with asymmetrical ailerons, you will end up with a tilted yoke.

my experience is the higher you rig the flaps and ailerons the faster your plane will go. Any amount of droop is like putting your flaps down.

Edited by N201MKTurbo
Link to comment
Share on other sites

Okay, now the follow-on question that has been asked more than once ... where to get a set of travel boards? Hangar Toolbox seems to be defunct. I checked the zip file posted elsewhere on the forum and it contains a scan of the rudder travel board only. Does anyone have technical drawings of the wing boards for a C model, or is there another place to rent them from ?

Link to comment
Share on other sites

2 hours ago, 170driver said:

Okay, now the follow-on question that has been asked more than once ... where to get a set of travel boards? Hangar Toolbox seems to be defunct. I checked the zip file posted elsewhere on the forum and it contains a scan of the rudder travel board only. Does anyone have technical drawings of the wing boards for a C model, or is there another place to rent them from ?

There are only 2 MSC’s in Canada, one in Calgary, and mine in Ontario.  It’s not really a tool I’d ship across the country.  You may find an MSC south of the board who are closer and able to help you.

Do you have a maintenance manual for your plane?

Clarence

Link to comment
Share on other sites

There are only 2 MSC’s in Canada, one in Calgary, and mine in Ontario.  It’s not really a tool I’d ship across the country.  You may find an MSC south of the board who are closer and able to help you.
Do you have a maintenance manual for your plane?
Clarence

I have the maintenance and parts manuals for the plane. The shop that does the annuals is good about letting me do work under supervision. I haven't looked carefully at the manual yet, but it seems to me the rod ends at the flaps need to be lengthened an equal amount on each side to get the counterweights flush, and flap stops adjusted equally after that to get trailing edges aligned.

Dave


Sent from my iPhone using Tapatalk
Link to comment
Share on other sites

1 hour ago, 170driver said:


I have the maintenance and parts manuals for the plane. The shop that does the annuals is good about letting me do work under supervision. I haven't looked carefully at the manual yet, but it seems to me the rod ends at the flaps need to be lengthened an equal amount on each side to get the counterweights flush, and flap stops adjusted equally after that to get trailing edges aligned.

Dave


Sent from my iPhone using Tapatalk

The rod ends on the I/b ends of the flaps determine down travel, the stop bolts on the o/b end of the flaps controls up positioning.

Aileron rigging starts at the yokes, then the centre bellcrank positioning under the floor, then the aileron bellcrank positioning in the wings as measured from the spar face, then ultimately the aileron positioning based on a travel board.  However the mass balance should be centred in the wing tip notch in cruise flight and flaps should align with the ailerons.

Clarence

Link to comment
Share on other sites

The rod ends on the I/b ends of the flaps determine down travel, the stop bolts on the o/b end of the flaps controls up positioning.
Aileron rigging starts at the yokes, then the centre bellcrank positioning under the floor, then the aileron bellcrank positioning in the wings as measured from the spar face, then ultimately the aileron positioning based on a travel board.  However the mass balance should be centred in the wing tip notch in cruise flight and flaps should align with the ailerons.
Clarence

I meant to say rod ends at the ailerons, not the flaps. The yoke is properly centred in wings level cruise, and the plane flies more or less hands off with the PC disconnected, so wouldn't I just have to lengthen the rod end at each aileron by the same amount each side until the mass balances are centred? After that the flap stops would be adjusted "up" by the same amount on each side until trailing edges aligned with ailerons.

Dave


Sent from my iPhone using Tapatalk
Link to comment
Share on other sites

26 minutes ago, 170driver said:


I meant to say rod ends at the ailerons, not the flaps. The yoke is properly centred in wings level cruise, and the plane flies more or less hands off with the PC disconnected, so wouldn't I just have to lengthen the rod end at each aileron by the same amount each side until the mass balances are centred? After that the flap stops would be adjusted "up" by the same amount on each side until trailing edges aligned with ailerons.

Dave


Sent from my iPhone using Tapatalk

From your description you have it correct.  I would also measure the positioning of the aileron bellcranks while you’re at it.

Clarence

Link to comment
Share on other sites

From your description you have it correct.  I would also measure the positioning of the aileron bellcranks while you’re at it.
Clarence

Thanks Clarence
Will probably be a couple of weeks before I get to this. I'll be sure to record before & after cruise speeds & post the numbers.


Sent from my iPhone using Tapatalk
Link to comment
Share on other sites

I am working on a 1976 M20F at the moment. Followed the rigging instructions in the manual and found a few rod ends that need adjustment. With the ailerons locked on neutral using a strait edge on the yoke they are properly faired a 0 to -2 degrees down. Once the straight edge is released they have a right wing down spring back. I must be missing something. Maybe @M20Doc or @Sabremech has some insight?

Video on you tube.

 

 

Link to comment
Share on other sites

18 minutes ago, Bayern Speed said:

I am working on a 1976 M20F at the moment. Followed the rigging instructions in the manual and found a few rod ends that need adjustment. With the ailerons locked on neutral using a strait edge on the yoke they are properly faired a 0 to -2 degrees down. Once the straight edge is released they have a right wing down spring back. I must be missing something. Maybe @M20Doc or @Sabremech has some insight?

Video on you tube.

 

 

To set the aileron positions properly you need to have someone on each aileron pushing up. that is what happens in flight. The spring back you are seeing is coming from the rudder aileron interconnect springs. Don't worry about it. You could remove the springs while you are rigging it if it makes things easier. 

Link to comment
Share on other sites

32 minutes ago, Bayern Speed said:

I am working on a 1976 M20F at the moment. Followed the rigging instructions in the manual and found a few rod ends that need adjustment. With the ailerons locked on neutral using a strait edge on the yoke they are properly faired a 0 to -2 degrees down. Once the straight edge is released they have a right wing down spring back. I must be missing something. Maybe @M20Doc or @Sabremech has some insight?

Video on you tube.

 

 

Is the nose wheel straight?  You’re getting some input from the aileron/rudder interconnecting springs under the pilot’s seat.

Clarence

5D625265-B26C-49E4-88FA-DE53E384E3DC.png

Edited by M20Doc
Link to comment
Share on other sites

@M20Doc nose wheel is straight. Even jacked aircraft to get any possible unintended pressure from nose wheel out of the system. As far as I can tell it is the mixer springs. One appears visually to be tighter that the other. I guess we will go fly it and report back.

Link to comment
Share on other sites

1 hour ago, N201MKTurbo said:

To set the aileron positions properly you need to have someone on each aileron pushing up. that is what happens in flight. The spring back you are seeing is coming from the rudder aileron interconnect springs. Don't worry about it. You could remove the springs while you are rigging it if it makes things easier.

I considered that! I think we will fly it and verify good or bad results.

Link to comment
Share on other sites

1 minute ago, Bayern Speed said:

I considered that! I think we will fly it and verify good or bad results.

That is the best way. You will just have to look at them and say that it seems up about an 1/8" or so and then adjust them where you want them. Then repeat until you are tired of adjusting it.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.