What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Come on Folks... Attaching the Elevator correctly is NOT that difficult!

Walt

Walt

Well Known Member
Why is it that so many folks can't seem to get this right, it's so simple but I find it incorrect so often its amazing :confused:

Today during a condition inpection, on a nicely built 8, I find all the elevator attach bolts loose (rod end to hinge), as soon as I find this I know what's coming... no or incorrect spacing on the center support bearing. Sure enough when I tightened all the bolts down so the rod end bearings can actually act like bearings rather than bushings, the elevator is locked up tight. Loosen the center bearing and voila the elevator comes back to life (actually because the bearings had not been acting as bearings for so long it took lots of lube and working them back an forth to free them up).

Then I check to see what was used for spacers and guess what, none there, nata, zippo... no spacers at all, not even a single lowly washer!

So now I am tasked with making the correct size spacers for the center bearing, not an easy task at this point unless I also want to remove the rudder (which by the way all those bolts were loose too and same situation with frozen bearings).

The process is simple when installing the elevator:
1) Tighten up all the elevator attach points except the center bearing, Hinge bolts SHALL NOT be loose! Elevators should move freely.
2) Make the correct (exact) size spacers out of tubing or whatever you prefer for both sides of the center bearing (they will be different sizes).
3) Install spacers made in step 2 and tighten down center bolt, elevators should remain free just like they were in step 1.
If the elevator binds up return to step 2. Do not loosen hinge bolts in order to free up elevator!

I literally find this condtion on 75% or more of the aircraft I inspect.

It seems that when folks find things binding their answer is to just loosen up the bolts :eek:

Rod end bolt SHALL be tight (torqued) so that the bearing can actually work as a bearing.

Thanks for your cooperation :D
 
Last edited:
Pictures! We need pictures!

As usual Walt you have hit on something we must be neglecting if you are finding 75% wrong.


Pictures of "wrong" and "correct" would be helpful.
 
Fiber lock nus?

As long as we're talking elevator bolts I have a question. Why are we using fiber lock nuts on bolts that participate in a hinge or any rotating assembly? Every certified plane that I've ever been around used a castle nut and cotter pin in these applications.

Just curious what your thoughts are. I have read reports where people have found the nuts off at the aileron bellcrank bolt.
 
Walt,

Posts like this one and your flaring one are just the type we need.

Keep'em coming.
 
As long as we're talking elevator bolts I have a question. Why are we using fiber lock nuts on bolts that participate in a hinge or any rotating assembly? Every certified plane that I've ever been around used a castle nut and cotter pin in these applications.
Click to expand...
This kinda illustrates what Walt is talking about. Apparently there are a number of builders who don't understand the different methods of securing a hinge point (bearing vs bushing). I actually see this on lots of bottom-feeder certified planes, and thee are "supposed" to have been done by licensed individuals. Another one that fuses me is grease on Cessna fowler tracks instead of lube in the roller bearing. Double Duh.
 
One other point .....

I too had this problem but since Walt's was keeping me on the straight and narrow during the build, I had to get my elevators rigged correctly before my first flight. BTW, I thought it was just fine until Walt checked it and told me it not even close to being "fine".

It took me a few days of work to get it right because I needed to tweak more than just the spacers. I found that I had the bearings slightly mis-aligned, so I had to remove and re-install both elevators many times to get ALL 5 BEARING (2 in each elevator + the center bearing) in alignment.

I went from having quite a bit of drag (when all the nuts & bolts were tight) to having an elevator that would move freely with just the slightest touch. It was well worth the effort.
 
aerhed said:
This kinda illustrates what Walt is talking about. Apparently there are a number of builders who don't understand the different methods of securing a hinge point (bearing vs bushing). I actually see this on lots of bottom-feeder certified planes, and thee are "supposed" to have been done by licensed individuals. Another one that fuses me is grease on Cessna fowler tracks instead of lube in the roller bearing. Double Duh.
Click to expand...

If it's a bearing, Clamp it! (lock nut OK)

If it's a bushing, Cotter Pin it! (use a castle nut)

Should work for all cases ...and is certainly true on my certified Grumman...:)
 
Phil said:
Walt,

Posts like this one and your flaring one are just the type we need.

Keep'em coming.
Click to expand...

I was thinking the same thing. I am getting ready to continue a build I purchased and this is the type of information I am trying to absorb.

Thanks Walt.
 
Getting the elevator to float freely with all 4 rod end fasteners, the center bearing fastener and the elevator pushrod bolt properly torqued, took me the better part of a month to get right, what with bending flanges, shimming bearings, etc. In my case, I had to tweak every steel bearing support bracket on the back of the horizontal stabilizer. Since the holes in the bearing support brackets aren't slotted to allow for production tolerances, it was made even more difficult. I burned up at least 30 hours just getting those parts right.

Hopefully that is not representative of a typical aircraft production environment. Because if it is, that would go a long way towards explaining why it's so expensive to build airplanes.
 
Why oh why would anyone put forward an aircraft for condition inspection in the state that Walt describes??

I would be mortified if I presented work like that for inspection.
 
Here's why.

DaAV8R said:
....As long as we're talking elevator bolts I have a question. Why are we using fiber lock nuts on bolts that participate in a hinge or any rotating assembly?.

.
Click to expand...

Robert, the rod end bearing's center piece is the bearing and needs to be stationary, and that is accomplished by the bolt being tight. The bolt is NOT the bearing, so it doesn't need to be drilled with a cotter key.

If you'll look at our rudder cables, there the bolt IS the bearing and is loose enough to function as such, is therefore cotter-keyed.

Best,
 
Geico266 said:
Pictures! We need pictures!

As usual Walt you have hit on something we must be neglecting if you are finding 75% wrong.


Pictures of "wrong" and "correct" would be helpful.
Click to expand...

Hard to take a pictures of a loose bolt vs a tight one and I'd have to use a mirror to take a pic of the missing spacers, but I will keep this in mind and will try to post pictures.

DaAV8R said:
As long as we're talking elevator bolts I have a question. Why are we using fiber lock nuts on bolts that participate in a hinge or any rotating assembly? Every certified plane that I've ever been around used a castle nut and cotter pin in these applications.

Just curious what your thoughts are. I have read reports where people have found the nuts off at the aileron bellcrank bolt.
Click to expand...

See below, Gil nailed it.

az_gila said:
If it's a bearing, Clamp it! (lock nut OK)

If it's a bushing, Cotter Pin it! (use a castle nut)

Should work for all cases ...and is certainly true on my certified Grumman...:)
Click to expand...

Thanks Gil, you are spot on as usual.

Lars said:
Getting the elevator to float freely with all 4 rod end fasteners, the center bearing fastener and the elevator pushrod bolt properly torqued, took me the better part of a month to get right, what with bending flanges, shimming bearings, etc. In my case, I had to tweak every steel bearing support bracket on the back of the horizontal stabilizer. Since the holes in the bearing support brackets aren't slotted to allow for production tolerances, it was made even more difficult. I burned up at least 30 hours just getting those parts right.
Click to expand...

Thanks for taking the time to do it right, I luv ya man!

islandmonkey said:
Why oh why would anyone put forward an aircraft for condition inspection in the state that Walt describes??

I would be mortified if I presented work like that for inspection.
Click to expand...

I do inspections for many folks that bought their RV and have no idea on what is correct. The fact that I keep finding this condition means to me that builders either don't understand the mechanics of this section or just don't want to take the time to do it right.

In any case, I would like everyone to go out right now and check that their flight control bolts are all tight, and if not FIX IT. Van's does not use any bushings in the flight controls (except for bellcranks) so all bolts should be tight. If your flight controls bind up when you tighten em you got some work to do.
 
A frequent problem I see is the bearing jam nuts being loose. This transfers a lot of load to the nut plates instead of the spars.
 
Very interesting find.

This is one of the things I check on my A/W inspection and I rarely find this problem.
I do find loose jam nuts on the rod-end bearings themselves, but typically not the bolt/nut combination.
 
Last edited:
I too reworked my elevator after a prior posting from Walt a couple of years ago. It only took me a couple of hours of fiddling with washers before I got it right. I did not need any spacers other than the washers.
Unfortunealty, there was a lot of mis-information being bounced around on another forum on what was acceptable or "correct" and what was not some years ago when I was assembling them. I even carried that mis-information onto this forum until I truly understood the problem. That is one reason I left that other site.
VAF has a much better peer group to insure that mis-information does not lead people down the wrong path.
 
I think part of the problem stems from the fact that there are people with non-technical backgrounds building these things, occasionally with sub-optimal supervision. The reason I sweated mine (while thinking evil thoughts about the lack of adjustability in the metal tabs) was because I understand how bearing systems are supposed to work- but I get paid to know that stuff in my day job. Consider how often it's explained here how to properly install and tighten the brass bushings in the control bellcranks. Without prior knowledge, some folks assume that the bolt has to be loose, since obviously the thing pivots around the bolt, right? Wrong. But not all builders read this forum.
 
I remember fussing with this for a VERY long time to get right and I felt like I was flailing for much of that time. This is the first time I have read the correct ORDER of tightening...rod ends first, THEN center bearing to determine shim sizes on the center bearing. It's been a few years --- did I just miss the order in the instructions or is this order gained from years of experience?

Mine is going down for paint in a few months and the tail (and everything else) will be coming off. This is very timely for when the tail goes back on! I was planing on lots of zip locks for individual bolts/washers/spacers/nuts with drawings for each fastener set so I could get things back to where I started, quickly. Many spots have different numbers and locations of washers for free movement.

Thanks Walt:D

Jeremy Constant
 
ELEVATOR BEARINGS

THERE HAVE BEEN OCASIANS WHEN THE AIRCRAFT IS PAINTED PEOPLE OTHER THAN THE ORIGINAL BUILDER DISASSEMBLE AND RE ASSEMBLE THE AIRPLANE I WOULD SUGGEST ANY TIME THIS HAPPENS A THOURGH INSPECTION BE GIVEN ESPECIALY IF THE OWNER IS NOT THE BUILDER
 
an easier path:

Now, maybe I figured this out as I built one after another aircraft, or maybe it was in a previous job, which also required a succession of things to align...

First, you have to understand that while the QB parts you are using are very good indeed, they do carry with them 'production tolerances'. This particular lesson comes from building many non-QB assemblies. So:

Build sequence: H stab, then elevs. Right?

Build requirement: the elevs have to fit the stab, and operate freely. Duh? Maybe not, esp to one who might be new to a/c assembly. So, how ya gonna make sure the build requirement is met, in the easiest manner?

Fit the spar w/root rib and horn to the stab before building these bits into an elevator. Shim as required (likely, at the center bearing). Now you can proceed with the elev assembly, as the bearing centers and overall length of the spar are not gonna change to any measurable degree.

When I wrote the F1 assembly manual, I included these production tolerances in my plan (past experience/School of Hard Knocks), so I have the fellas install the bearings to the elev spars (1st, install doublers/nutplates etc), fit the steel brackets to the bearings (tightly), and then use the spar to set the locations/centerlines of the brackets on the stab spar. This process eliminates any tolerances due to bearing locations, and sets the tip rib clearance. Once the brackets are drilled & riveted to the stab spar, the builder is to re-attach the elev spar to the stab and bolt the horn to the center bearing, using the indicated washers. The horn is drilled to the elev spar LAST, while everything is in place, again, eliminating 'production tolerances'.

Seems a similar process could be used with the QB parts supplied with the Vans kits? Sure would make life easier! Tell me if I'm wrong!

Another end-around fitting and re-fitting the elevs to get things right would be to do this fitting on the bench, before the stab/elev assy is bolted to the fuselage. Shot bags on the stab will keep the parts from bouncing off the floor....gravity is the one thing that ALWAYS works!:eek:

Have a great Thanksgiving!

Carry on!
Mark
 
Lost/deferred issues

Building the tail is one of the first steps in what for most is a multi year build. Most of us get better with time and tend to forget some of the issues we deferred for a later date or more information early on.
Perhaps DARs should insist on seeing a proposed yearly inspection plan and suggest that it be performed before their first visit?
 
Jamie said:
A frequent problem I see is the bearing jam nuts being loose. This transfers a lot of load to the nut plates instead of the spars.
Click to expand...

That can be a serious issue. The nut plates are just held in with two tiny rivets. Once those rivets get loose it allows a bunch of the type of play that is conducive to flutter.
 
jdeas said:
Building the tail is one of the first steps in what for most is a multi year build. Most of us get better with time and tend to forget some of the issues we deferred for a later date or more information early on.
Perhaps DARs should insist on seeing a proposed yearly inspection plan and suggest that it be performed before their first visit?
Click to expand...

All included in the regulations!
 
F1Boss said:
Now, maybe I figured this out as I built one after another aircraft, or maybe it was in a previous job, which also required a succession of things to align...

First, you have to understand that while the QB parts you are using are very good indeed, they do carry with them 'production tolerances'. This particular lesson comes from building many non-QB assemblies. So:

Build sequence: H stab, then elevs. Right?

Build requirement: the elevs have to fit the stab, and operate freely. Duh? Maybe not, esp to one who might be new to a/c assembly. So, how ya gonna make sure the build requirement is met, in the easiest manner?

Fit the spar w/root rib and horn to the stab before building these bits into an elevator. Shim as required (likely, at the center bearing). Now you can proceed with the elev assembly, as the bearing centers and overall length of the spar are not gonna change to any measurable degree.

When I wrote the F1 assembly manual, I included these production tolerances in my plan (past experience/School of Hard Knocks), so I have the fellas install the bearings to the elev spars (1st, install doublers/nutplates etc), fit the steel brackets to the bearings (tightly), and then use the spar to set the locations/centerlines of the brackets on the stab spar. This process eliminates any tolerances due to bearing locations, and sets the tip rib clearance. Once the brackets are drilled & riveted to the stab spar, the builder is to re-attach the elev spar to the stab and bolt the horn to the center bearing, using the indicated washers. The horn is drilled to the elev spar LAST, while everything is in place, again, eliminating 'production tolerances'.

Seems a similar process could be used with the QB parts supplied with the Vans kits? Sure would make life easier! Tell me if I'm wrong!

Another end-around fitting and re-fitting the elevs to get things right would be to do this fitting on the bench, before the stab/elev assy is bolted to the fuselage. Shot bags on the stab will keep the parts from bouncing off the floor....gravity is the one thing that ALWAYS works!:eek:

Have a great Thanksgiving!

Carry on!
Mark
Click to expand...

Wow, do I wish I had had that to read before I started, longer ago than I care to think about. Well done. Would have saved me a lot of time and headache.

Happy Thanksgiving to you, too!
 
As someone very ignorant about the entire build process but trying to learn what is the best way to check the work on a existing aircraft? I am very comfortable that the builder (Robbie Attaway) did a great job but would still after reading this thread like to get mine looked at and checked out. From what I have read in this thread I don't feel that I can do the inspection myself unless there are some easy key areas to focus on and check. Is there a inspect the elevator for idiots primer out there somewhere? I know I am going to need pictures!

George
(lacking knowledge in Charlotte!)
 
sailvi767 said:
As someone very ignorant about the entire build process but trying to learn what is the best way to check the work on a existing aircraft? I am very comfortable that the builder (Robbie Attaway) did a great job but would still after reading this thread like to get mine looked at and checked out. From what I have read in this thread I don't feel that I can do the inspection myself unless there are some easy key areas to focus on and check. Is there a inspect the elevator for idiots primer out there somewhere? I know I am going to need pictures!

George
(lacking knowledge in Charlotte!)
Click to expand...

The easiest way to check that the elevator is adjusted properly is to just make sure ALL the bolts are tight and that the elevator moves freely, you should barely have to push on it to cause it to move down and it should coast back to it's "up" postion on it's own accord.

And as brought up previously, always check the jam nuts to be sure they are tight.
 
Auto pilot servo...

Consider that an auto pilot servo will add significant drag to the idea of 'coast'

Even more drag from stick boots and seat cushions...
 
Last edited:
[email protected] said:
Consider that an auto pilot servo will add significant drag to the idea of 'coast'
Click to expand...

Not sure what AP you are using but none of the ones I have worked with (TT & S-tec) add any noticable drag to the system. When I get done adjusting an elevator it will coast down with an autopilot servo attached.
 
A hint: When I set up my elevators I used a length of steel rod run through each set of bearings. That would be one rod through three bearings. By doing that I was able to get a visual alignment of the bearings, when the rod looked straight I knew I was getting close. I just kept pulling the rod out and making adjustments until I hit perfection. Perfection being an even hinge line gap between the elevator and stabilizer and zero resistance to movement of the elevator.
 
Last edited:
Walt said:
The easiest way to check that the elevator is adjusted properly is to just make sure ALL the bolts are tight and that the elevator moves freely, you should barely have to push on it to cause it to move down and it should coast back to it's "up" postion on it's own accord.
Click to expand...

Except that if the elevators are balanced per the manual (neutral) they won't coast to the up position on their own.

Skylor
 
skylor said:
Except that if the elevators are balanced per the manual (neutral) they won't coast to the up position on their own.

Skylor
Click to expand...

If you disconnect the pushrod the above is true, however, with it connected the weight of the rod will pull it down (I am referring to completed aircraft, not ones under construction).
 
And for those of us with non-balanced elevators, (RV-3), we just have to make sure that they feel nice and smooth - they don't float, they go "thunk! ;)

Good thread Walt - it makes me want to check my spacers one mor etime before Mel comes...
 
Last edited:
Oddly, I felt compelled to check both the RV-10 project and the -6A that's been flying for 3 years now. All good, but it felt good to check.
 
Drilling HS steel brackets

I'm getting into this thread a little late, but I have a question on drilling the HS steel brackets where the elevator rod ends attach. While trying to fit the attach bolts thru the steel brackets, the paint/powder coat was to thick and I had to open it up with a drill bit to get the bolt through. One of the brackets was at an angle and got very slightly wobbled out. After all the hardware was installed and tight there was no play, but after reading this thread it brings up a concern and questions on the correct way to rig the elevators. I may be missing it but the construction manual seems to offer little insight or steps. :confused:

Thanks,
 
Last edited:
F1Boss said:
....Fit the spar w/root rib and horn to the stab before building these bits into an elevator. Shim as required (likely, at the center bearing). Now you can proceed with the elev assembly, as the bearing centers and overall length of the spar are not gonna change to any measurable degree.....
Carry on!
Mark
Click to expand...

Sorry for responding to a 3-year-old thread. Just found it today, and I hope Walt still drops by these old threads to also accept my thanks for posting.

Anyway Mark, if I remember correctly, I think we did what you're decribing on the RV-4, way, way before prepunching of any kind. There was no other way to get the rod end shank holes and doubler plates in their exact spots on the elevator spars. In fact, we might even have drilled slightly larger rod end bearing shank holes in just the elevators and rudder spars, allowing the rod end bearing shanks to move around a bit, and after they were bolted into the HS brackets, we then tightened jamnuts on both sides of the spar/doubler combo. Then drilled through some previous #30 holes in the doubler plates and also through the elevator spar, and that set the rod end bearings' position on the elevator spars. Then we built the elevators.

Ah, memories. And they WEREN'T good old days!
 
So ...

The control stick assembly has bushes for all moving joints – the bush as fitted to the steel weldments (tube) may be a press fit in the steel tube as received from VANs (the tube contracts when welded to the stick assembly) – to ensure that the bolt can be tighten to the required torque – you may have to file down the steel tube (but NOT the bush – the bush have to be LONGER than the steel tube) so that when you clamp up the bush in the steel “U” - to allow the steel tube to turn on the bush – you have to ream the steel tube – as now the bush is clamped in place by the bolt – and will not rotate – the steel tube (which is welded to the stick assembly) has to be able to freely rotate on the bush.
 
Was there a question in there? You were absolutely correct (I also like to smear a dab of bearing grease on the bushing both for lube and corrosion prevention when final assembling them). The bushings for my RV-10 sticks were delivered installed in the sticks, so I didn't have to ream but I did have to trim the bushing to fit snugly in the steel 'U' and then trim the tube on the stick to be slightly shorter. Even though the attachment bolt is drilled, this is one case where you torque the nut before putting in the cotter pin; the bolt is not a bearing.

I re-read this thread and wanted to add some words about alignment. When I built my tail surfaces, the stabilizer spars were straight and I could visually check the alignment of the hinge points by sighting through the holes. Avery used to sell a couple of machined buttons that would fit in the bearing holes and allow you to stretch a string from one end to the other for a more precise check; it was necessary on the non-pre-drilled kits but I used it on the pre-drilled -10 surfaces as well.

If those hinge points line up, then there should be no problem with the elevator/rudder line up as well. You can adjust the rod ends as necessary to achieve a straight run for those surfaces' hinges. However, I noticed two 'gotchas' in both my builds. The first is the spacers at the center bearing for the elevator. It pays to take the time to get them right; you don't want the horns loaded laterally as it will stiffen up the works even if the hinge line is straight. As Walt said in the thread title, it's not hard to do. I don't think I spent more than a couple of hours doing all the adjustments on the -10.

The second problem is the vertical stab. First you attach it to the last bulkhead. Now, if you go ahead and drill the forward attachment, you risk pushing or pulling your rear spar slightly out of line. Instead, install the rudder and make sure everything's lined up and then drill the forward attachment with the rudder installed. That way the spar and hinge line is forced to remain in alignment. The rudder on my RV-6A is just slightly stiff (still moves under it's own weight but not entirely free), which doesn't bother me because I put return springs on the system anyway. But I remembered the problem and the -10 rudder moves freely (I was planning a yaw servo and wanted to be sure there was no effort for the servo).
 
Re-posting

I am re-posting this thread (is that correct use of terms?) as I have had two instances recently of this common "problem" come up where by the owner/pilot was not aware.
One was discovered assisting a neighbor with a CI. I had not touched his airplane before but after feeling the resistance of the stick and manually moving his elevator, it was obvious that things where not moving freely.
The second was a comment buried in a different thread about having to "loosen the elevator bolts" before ferrying an airplane home. I PM'd the owner about it and indeed he was not aware. A search revealed this excellent description from Walt in an older post.
Walt is not only passionate about safety, he is passionate about doing things the right way. Those two are usually connected.
 
Elevator Hinge friction

Instead of starting a new thread I thought this would be the perfect place for any new information about this subject.

So I have read all that I can find about the proper way to set up the elevators to be friction free (or as close as one can come).

Walt makes perfect sense in the original post (so many years ago ;))

But no one talks about how they adjusted the elevator hinges when there was binding in just the hinges...not with the center bearing bolt installed.

My right elevator swings free when the hinge bolts are torqued (center bearing not connected). My left elevator binds when the hinge bolts are torqued.

The center bearing hole has been drilled to size and I understand how to shim it when I finally have a free floating left elevator.

Question:
Is there a way to know what needs adjusting or do I just start adjusting hinges and hope for the best?

(moderator: Feel free to remove this post if this is not the appropriate place and I'll start a new thread)
 
mfleming said:
Instead of starting a new thread I thought this would be the perfect place for any new information about this subject.

So I have read all that I can find about the proper way to set up the elevators to be friction free (or as close as one can come).

Walt makes perfect sense in the original post (so many years ago ;))

But no one talks about how they adjusted the elevator hinges when there was binding in just the hinges...not with the center bearing bolt installed.

My right elevator swings free when the hinge bolts are torqued (center bearing not connected). My left elevator binds when the hinge bolts are torqued.

The center bearing hole has been drilled to size and I understand how to shim it when I finally have a free floating left elevator.

Question:
Is there a way to know what needs adjusting or do I just start adjusting hinges and hope for the best?

(moderator: Feel free to remove this post if this is not the appropriate place and I'll start a new thread)
Click to expand...

Wow, old thread!
Bearing side loading is what generally causes binding, try using a washer to fill the gap between the hinge and bearing so that you don't 'pull' the elevator to one side when you tighten the hinge bolts.
 
Walt said:
Wow, old thread!
Bearing side loading is what generally causes binding, try using a washer to fill the gap between the hinge and bearing so that you don't 'pull' the elevator to one side when you tighten the hinge bolts.
Click to expand...

And that can be a bit of an exercise in patience to figure out exactly which bearing is loading, and in which direction. Buy the "washer wrench" tool if you don't already have it, you'll definitely be glad to have it for this work.
 
When should we approach this task - during the empennage build or later when mounting everything up?

I'm close to finished with my emp., and I *think* I read something about mounting the elevators to the hstab.
 
It works much better if you attach the elevators to the HS on the bench so you can easily see the spacers needed. Be sure then to mark them or make a note for final assembly. I have done a few of these and found it easier to make a spacer that fits rather than use washers. Makes it easier to install during final assembly?
 
Walt said:
Wow, old thread!
Bearing side loading is what generally causes binding, try using a washer to fill the gap between the hinge and bearing so that you don't 'pull' the elevator to one side when you tighten the hinge bolts.
Click to expand...

Walt your brilliant :D

The side load was indeed what was adding the friction to the left elevator. I tweaked one hinge bracket ever so slightly and added a washer to the second hinge. Now both elevators are perfect...just like before they were torqued.

Now on to the center bearing...washers were either to skinny or to fat. I was going to use a piece of ?" ID tubing but the bearing surface seems small compared to the washers...might look for something else :cool:
 
... Fitted my elevators on the bird this weekend, and found a bit more drag than I would have hoped. Individually, the elevators seem almost friction-free and will naturally rotate to one of the stops. With the center bolt torqued, there's a bit of extra friction that causes them to sick just a bit. Seems like some iteration is in order. Thanks OP's!
 
Last edited by a moderator:
wjb said:
... Fitted my elevators on the bird this weekend, and found a bit more drag than I would have hoped. Individually, the elevators seem almost friction-free and will naturally rotate to one of the stops. With the center bolt torqued, there's a bit of extra friction that causes them to sick just a bit. Seems like some iteration is in order. Thanks OP's!
Click to expand...

Yep! I measured the gaps and made spacers on the lathe. I think I iterated once more with a different spacer thickness. When it is all correct, it should flop around with no friction.
 
DaAV8R said:
As long as we're talking elevator bolts I have a question. Why are we using fiber lock nuts on bolts that participate in a hinge or any rotating assembly? Every certified plane that I've ever been around used a castle nut and cotter pin in these applications.

Just curious what your thoughts are. I have read reports where people have found the nuts off at the aileron bellcrank bolt.
Click to expand...

Seems you may not understanding how these bearings work. The fitting and bolt through the rod end bearing are fully torqued against the bearing center piece and the fitting is held in tension against this center section. It does not move or rotate relative to that bearing center section. Instead, the center section rotates freely against the outer race. Castelled nuts are only recommended when the rotation of the assemby applies a radial force to the nut or bolt, such as the nose gear nut under the bellevilles. This does not occur with a rod end bearing. If the nut is not fully torqued against the bearing, like a on a wheel bearing pair on an axle, then a castellated nut is used.

What you have likely seen in certified gear are bushings, not bearings, and they typically need castellated nuts.
Larry
 
Last edited:
mfleming said:
Walt your brilliant :D

The side load was indeed what was adding the friction to the left elevator. I tweaked one hinge bracket ever so slightly and added a washer to the second hinge. Now both elevators are perfect...just like before they were torqued.

Now on to the center bearing...washers were either to skinny or to fat. I was going to use a piece of ¼" ID tubing but the bearing surface seems small compared to the washers...might look for something else :cool:
Click to expand...

Go to Menards or home depot and buy some thin sheet steel. The thin stuff should be quite a bit thinner than both the std and L washers and you can cut / drill your own ultra thin washers to give you more options to work with. They don't need be be perferctly round or pretty, just a well drilled hole and a bit larger than the std washers.
 
I’m interested in how one defines “binding”? If an elevator moves freely with no discernible resistance by hand but has JUST enough friction in the system to resist gravity when held at a certain point, is that elevator considered bound?
 
You must log in or register to reply here.
Back
Top