How to adjust the Flaparon Linkage on RV-12iS

[gmcjetpilot]

Helping a builder with Phase 1, slight left wing heavy. Looking and TE bend radius all looks good except two bays (about 6" each) on left Flaparon. If it were to decrease bend radius more it would make the left wing heavier. Right now we are doing nothing. Van says this is normal and on their S-LSA they typically have to do some tweak's. Plane is well built and fly's well, book specs. Eventually want to fine tune this (without over dooing it).

My question is how difficult is it to get at the mxing links? What do you suggest in how to adjust.

Looking at the TE alignment there looks to be some out of alignment or rig (slight). But it also seems to be opposite of what I'd expect for slight LEFT wing heavy. Again the condition is minor, but noticeable. I don't want to increase or make the issue worse.

Increasing the RIGHT Flaperon TE radius is not an option as that one has perfect bend radius and any more would be over done.

BTW I am a TE expert, in that I mean 25yrs ago with my RV-4 I over did the aileron TE bend and ended up reskinning one aileron. I know to be very careful, make tiny incremental changes between flight test.

May be leave it alone? The plane has two 180 lb pilots, full to half fuel. As I said it flys nice but not hands off. May be this is an RV-12iS thing and chasing this down to the Nth degree of roll perfection is not needed or possible?

 

[Tony_T]

Helping a builder with Phase 1, slight left wing heavy. Looking and TE bend radius all looks good except two bays (about 6" each) on left Flaparon. If it were to decrease bend radius more it would make the left wing heavier. Right now we are doing nothing. Van says this is normal and on their S-LSA they typically have to do some tweak's. Plane is well built and fly's well, book specs. Eventually want to fine tune this (without over dooing it).

My question is how difficult is it to get at the mxing links? What do you suggest in how to adjust.

Looking at the TE alignment there looks to be some out of alignment or rig (slight). But it also seems to be opposite of what I'd expect for slight LEFT wing heavy. Again the condition is minor, but noticeable. I don't want to increase or make the issue worse.

Increasing the RIGHT Flaperon TE radius is not an option as that one has perfect bend radius and any more would be over done.

BTW I am a TE expert, in that I mean 25yrs ago with my RV-4 I over did the aileron TE bend and ended up reskinning one aileron. I know to be very careful, make tiny incremental changes between flight test.

May be leave it alone? The plane has two 180 lb pilots, full to half fuel. As I said it flys nice but not hands off. May be this is an RV-12iS thing and chasing this down to the Nth degree of roll perfection is not needed or possible?

Before doing anything too drastic I would simply check the extension of the flaperon bearings. The flaperons are huge and the 11/32" dimension should be exact on all the bearings.

 

[dbhill916]

Agree with Tony_T. If you fiddle with the linkages/mixer, all you will do is change where the stick will naturally point with no pressure. It won't change how the plane flies. I found that making a full rotation on the outboard bearing and a half rotation on the inbound bearing nicely balanced my heavy wing. Unfortunately, I don't recall if I raised/lowered the bearings and I don't recall if I adjusted the heavy or light wing. Luckily, it's an easy process to reverse if you discover you adjusted the wrong way on the first guess.

I ended up with a plane that is slightly Left heavy solo and slightly R heavy with a passenger. I think that's as close to perfect as you can get without dynamic roll trim. Good luck and fly safe.

 

[Ralph Inkster]

Apply a small trim wedge to one of the flaparons? Putting it on the underside of the 'light' flaparon would make it less obvious visually.

 

[gmcjetpilot]

Great tips. Getting at the mixer is a pain, and dealing with one bearing relatively easy to get at would be great.

I edited my original post. We went flying today, Got a better look at the Left and Right Flaperons. The Right flaperon is ever so slightly (1/16" to 3/32") lower (more lift) relative to wingtip trailing edge, when the Left Flaperon is aligned with wing tip. That would explain the left wing heavy, or right wing light. Again the roll is slight. I will pass on this information and help builder sort it out.

May play with the trim wedge with double sided sticky just to see the effect and as a temporary fix. I like to use balsa wood with some paint and double sided sticky tape or a temporary trim tab. They are light, shaped easy and also easy to remove later.

BONUS QUESTION. After we flew today, to calibrate G3X AOA, on the ground, after shut down, for no particular reason I giggled the control stick in pitch direction, forward/aft. I felt some play, I also jerked it around a bit more and heard cable slap? I am use to RV's (4/6/7/8/9) with push pull rods not cables for elevator. I assume RV-12 has cable elevator control cables running all the way back from a control quadrant/bell crank to tail. It flies nice like an RV should. Not worried but are there checks or cable tension? is play normal (guessing +/- 1/16" or max 3/16" total). Flight test of new plane, so asking dumb questions.

 

[daveyator]

The cables are adjusted using a tensiometer. 35lbs is the number off the top of my head, but check the plans. On mine both turnbuckles are almost fully screwed in.
Have a look at the PAP documentation. It calls for you to hold the left flaperon in trail and the right flaperon should be slightly low,
3/16 is a number that sticks in my mind. I don’t have it handy, so check my work. My memory does not come with a guarantee.
hope this helps
Cheers DaveH

 

[Fisherpd]

As Daveyator indicated the flaperons do droop & the amount is verified during the PAP. They should have been rigged with 1/8th inch low on both sides during build. The tensiometer is used to set the tension in the cables & the PAP asks you to verify no slap when you jerk the stick around.

 

[N8DAV8R]

Great tips. Getting at the mixer is a pain, and dealing with one bearing relatively easy to get at would be great.

I edited my original post. We went flying today, Got a better look at the Left and Right Flaperons. The Right flaperon is ever so slightly (1/16" to 3/32") lower (more lift) relative to wingtip trailing edge, when the Left Flaperon is aligned with wing tip. That would explain the left wing heavy, or right wing light. Again the roll is slight. I will pass on this information and help builder sort it out.

May play with the trim wedge with double sided sticky just to see the effect and as a temporary fix. I like to use balsa wood with some paint and double sided sticky tape or a temporary trim tab. They are light, shaped easy and also easy to remove later.

BONUS QUESTION. After we flew today, to calibrate G3X AOA, on the ground, after shut down, for no particular reason I giggled the control stick in pitch direction, forward/aft. I felt some play, I also jerked it around a bit more and heard cable slap? I am use to RV's (4/6/7/8/9) with push pull rods not cables for elevator. I assume RV-12 has cable elevator control cables running all the way back from a control quadrant/bell crank to tail. It flies nice like an RV should. Not worried but are there checks or cable tension? is play normal (guessing +/- 1/16" or max 3/16" total). Flight test of new plane, so asking dumb questions.

These are not dumb questions, they could be safety critical. To offer some constructive criticism and hopefully not come across the wrong way; Based on these questions and some in another thread from this same airplane it seems like this builder would benefit from taking a pause and reviewing documentation carefully. Not so much the heavy wing, but the other things. Stand down, and help him go over all of the controls sections in the KAI and the checklists in the PAP. Answers to almost all of this are published. If nothing else, you may avoid chasing symptoms like they are your tail as a result of incorrect assumptions regarding rigging (like the neutral aileron positions)

There should not be cable slap with pitch controls. As I understand it the original KAI called for tightening cables to avoid the slapping. Later this was changed to a tension range as verified by a cable tension meter.

Many of us do feel some play that originates at the bushing between the stick and control column, but that's different than the slapping cables you seem to describe.

 

[Brantel]

These are not dumb questions, they could be safety critical. To offer some constructive criticism and hopefully not come across the wrong way; Based on these questions and some in another thread from this same airplane it seems like this builder would benefit from taking a pause and reviewing documentation carefully. Not so much the heavy wing, but the other things. Stand down, and help him go over all of the controls sections in the KAI and the checklists in the PAP. Answers to almost all of this are published. If nothing else, you may avoid chasing symptoms like they are your tail as a result of incorrect assumptions regarding rigging (like the neutral aileron positions)

There should not be cable slap with pitch controls. As I understand it the original KAI called for tightening cables to avoid the slapping. Later this was changed to a tension range as verified by a cable tension meter.

Many of us do feel some play that originates at the bushing between the stick and control column, but that's different than the slapping cables you seem to describe.

This a 1000 times over!

 

[gmcjetpilot]

These are not dumb questions, they could be safety critical. To offer some constructive criticism and hopefully not come across the wrong way; Based on these questions and some in another thread from this same airplane it seems like this builder would benefit from taking a pause and reviewing documentation carefully. Not so much the heavy wing, but the other things. Stand down, and help him go over all of the controls sections in the KAI and the checklists in the PAP. Answers to almost all of this are published. If nothing else, you may avoid chasing symptoms like they are your tail as a result of incorrect assumptions regarding rigging (like the neutral aileron positions)

There should not be cable slap with pitch controls. As I understand it the original KAI called for tightening cables to avoid the slapping. Later this was changed to a tension range as verified by a cable tension meter.

Many of us do feel some play that originates at the bushing between the stick and control column, but that's different than the slapping cables you seem to describe.

No offense taken. I appreciate everything you said. I have already informed my "student" and builder/owner we will investigate all of my concerns. I am an experienced RV builder, pilot, CFI/ATP, EAA Tech Council and mechanical engineer. I am very safety minded and picky. I have done flight test before both in large and small planes. So anything and everything gets attention no matter how small.

What I am not is a RV-12iS expert builder or 1000 hours in make and model. I have decent time in RV-12's giving dual in already flying RV-12's. I am comfortable in the plane, and this spacific aircraft is well made and flies to specifications or better. Impressive on 100HP. It is in fact the best RV-12iS I have flown. What I am doing is using VAF Forum as crowd sourcing a wealth of knowledge. It may take some ego check to admit you don't know and ask. I don't mind. It is not that the plane, builder or myself are not competent or there is systemic issues, just using CRM to the fullest. You never know where the good information is so check everything.

As far as the heavy wing ll it is so minor I am not concerned. We are talking being off 0.06", but that can cause a small roll hands off. No plane is perfect. I talked to Van's who makes S-LSA RV-12's. They say this is common with all their planes they build, and often needs tweaking. It is not some sign of weirdness, or poor workmanship. I talked to Van's and did not have to post this, but armed with VAF Forum and Van's info I feel 100% confident the issue is resolved.

As far as the other post, again abundance of caution and all of them minor. One that was odd that comes down to me not being a G3X expert. He a few config settings not set right for autopilot and ADS-B. Stein Air built the panel. Flight test showed that there was changes needed. We did that. That is the point of Phase 1.

The latest (again me being cautious if not 100% sure) I felt play in stick in pitch on ground. I did control checks before first flight (very thorough) and did not notice this before. But for no particular reason I giggled stick fwd / aft while sitting in the cockpit. There is a bit of play in the stick or dead band, in flight not felt. This is normal reading VAF Forum archives. However when I vigorously wiggled the stick like a pump, I heard something. Have to investigate now that I have more information from Van's Aircraft tech support, builder, and VAF Forum. Again Phase 1, and why we do this. Look at everything again and again.


Minor interference exhaust cowl and flaperon side of body, corrected.

I am an EAA Tech Councilor, +33 yr EAA member and have built two planes, MSME, worked for Boeing out of college in structures. I am VERY safety minded and SUPER PICKY. What I know is the plane flies very well. Workmanship and paperwork is spot on. Pilot is flying plane well as he learns it. He is a private pilot, current airplane owner (Piper 180), This is his first time as a builder (not mine). Working out small issues as you always do during Phase 1. Pilot is flying the plane well, but still more practice. I don't see anything alarming.

It is always good to step back and say what is up. I appreciate your concern.

As far as wing roll per Van's they recommend just fly before jumping into fix. So that is what we are doing. The owner and builder knows what to do, but we do not want to stop building his experience in the plane right now as it has no affect on overall safety or control. The plane stalls straight as if on rails. I could not be more satisfied on the performance and controllability.

 

[N8DAV8R]

It sounds like you are on the right track to get any last details sorted out. Also sounds like this builder is lucky to have some help. Most of what you described is what I assumed, and it is unlikely there are any major issues. Just little ones you can work out. One of the huge benefits of the RV-12 is that there is published guidance on a lot of the things that people have to otherwise figure out or adapt from other inspection and test programs.

I have a slightly heavy left wing too. I reduced it some by verifying 'flatness' of the top skin aft of the rear spar. Set a straight edge on the top skin and verify that it does not bend up or down aft of the spar. This had more effect than trailing edge adjustment although I will admit I applied a very light touch with that. Next on the list for will be making the rod end adjustment, but I'm not in a huge rush to do that based on following the same advice you have referenced from Van's. There is no real stick pressure necessary to remove the roll, natural resting position of the hand is enough. The airplane flies like a dream.

Good luck with the rest of P1.

 

[rvbuilder2002]

No offense taken. I appreciate everything you said. I have already informed my "student" and builder/owner we will investigate all of my concerns. I am an experienced RV builder, pilot, CFI/ATP, EAA Tech Council and mechanical engineer. I am very safety minded and picky. I have done flight test before both in large and small planes. So anything and everything gets attention no matter how small.

What I am not is a RV-12iS expert builder or 1000 hours in make and model. I have decent time in RV-12's giving dual in already flying RV-12's. I am comfortable in the plane, and this spacific aircraft is well made and flies to specifications or better. Impressive on 100HP. It is in fact the best RV-12iS I have flown. What I am doing is using VAF Fourm as crowd sourcing a wealth of knowledge. It may take some ego check to admit you don't know and ask. I don't mind. It is not that the plane, builder or myself are not competent or there is systemic issues, just using CRM to the fullest. You never know where the good information is so check everything.

As far as the heavy wing ll it is so minor I am not concerned. We are talking being off 0.06", but that can cause a small roll hands off. No plane is perfect. I talked to Van's who makes S-LSA RV-12's. They say this is common with all their planes they build, and often needs tweaking. It is not some sign of weirdness, or poor workmanship. I talked to Van's and did not have to post this, but armed with VAF Forum and Van's info I feel 100% confident the issue is resolved.

As far as the other post, again abundance of caution and all of them minor. One that was odd that comes down to me not being a G3X expert is he has had a few config settings ot right for autopilot and ADS-B. Both work but flight test showed that there was changes needed. We did that. That is the point of Phase 1.

The latest (again me being cautious if not 100% sure) I felt play in stick in pitch on ground. I did control checks before first flight (very though) and did not notice this. But for no particular reason I giggled stick fwd / aft while sitting in the cockpit. There is a bit of play in the stick or dead band, in flight not felt. This is normal reading VAF Forum archives. However when I vigorously wiggled the stick like a pump, I heard something. Have to investigate now that I have more information from Van's Aircraft tech support, builder, and VAF Forum. Again Phase 1, and why we do this. Look at everything again and again.

G3X configuration for autotrim, ADS-b and stall warning have or are being worked out very nicely.

Minor interference exhaust cowl and flaperon side of body, corrected.

I am an EAA Tech Councilor, +33 yr EAA member and have built two planes, MSME, worked for Boeing out of college in structures. I am VERY safety minded and SUPER PICKY. What I know is the plane flies very well. Workmanship and paperwork is spot on. Pilot is flying plane well as he learns it. He is a private pilot, current airplane owner (Piper 180), This is his first time as a builder (not mine). Working out small issues as you always do during Phase 1. Pilot is flying the plane well, but still more practice. I don't see anything alarming.

It is always good to step back and say what is up. I appreciate your concern.

As far as wing roll per Van's they recommend just fly before jumping into fix. So that is what we are doing. The owner and builder knows what to do, but we do not want to stop building his experience in the plane right now as it has no affect on overall safety or control. The plane stalls straight as if on rails. I could not be more satisfied on the performance and controllability.

The RV-12 has probably the most in depth and detailed documentation of any kit aircraft in existence.
Because of that there is no need to be an expert. Anyone with any level of familiarity should be able to follow the PAP check lists and verify all of the important details.
Perhaps another pass through the entire PAP would be a good idea?

 

[Brantel]

The RV-12 has probably the most in depth and detailed documentation of any kit aircraft in existence.
Because of that there is no need to be an expert. Anyone with any level of familiarity should be able to follow the PAP check lists and verify all of the important details.
Perhaps another pass through the entire PAP would be a good idea?

This times 1000!

 

[Amadeus]

Helping a builder with Phase 1, slight left wing heavy.

Long thread a couple years ago detailing how to correct this.

Tips for heavy right wing

Looking for some tips in correcting a heavy right wing. The ball is centered, but still a heavy right wing. I remember a tip from other RV models of crimping the trailing edge of the heavy wing aileron. Does this work on the RV12? Thanks

vansairforce.net

 

[azonslow]

Like rvbuilder2002 says, the PAP explains the issue and how to fix it in the section on "Lateral (roll) trim".