Fiberglass Fun & Empennage Fairings

Section 12

Fiberglass Tools

The plans specifically state that using tools on fiberglass will cause them to rapidly dull.  They state you should use a specific set of tools only for fiberglass.  Well I don't have any fiberglass specific tools, nor did I really know what I would need so I started doing some research. Perma-Grit tools are an option for an off the shelve product.  They came recommended in at least one EAA Video and found them mentioned on a few car websites. I might end up getting them at some point, but being that I'm completely new to working with fiberglass I wanted to go a different route.

This route was to build my own tools!  The concept is to have various shapes and sizes of tools to learn which work well, which don't and have the ability to attach various grits of sand paper to them. It's really no different than making your own sanding blocks when working with wood.  The key is to have pieces that are straight and rigid and it just so happens I have a mess of material I can use for this purpose.

So I dove into my parts graveyard (Where the mistakes go) and started pulling out some scraps that I could cut into various shapes.  The idea was to have pieces of various lengths and widths, the shortest piece is about 2" and the longest about 30".  After cutting to size I smoothed out all the edges to ensure decrease the risk of scratching any of the fiberglass work.

Various Fiberglass 'Tools'

Obviously the shapes aren't that useful without the sanding element so I looked at my assortment of sandpaper and decided to try 40, 80 and 150 grit papers.  The idea is to use 40 grit when I need to remove material, 80 when I need to remove material but be careful about it and 150 when I'm just trying to feather fiberglass over aluminium.  To adhere the Sandpaper to each piece I just used 3M Spray Adhesive which will allow it to stick while sanding.  Also it's easy to remove the paper with a heat gun and throw more paper on.

For the first batch of tools I just picked a handful of shapes that I thought I would use first.  I learned about halfway through the process it works best if you attach the piece to the paper before trimming to size.  A few of them I tried to use the tool as a template, cut it out and then attach it and there's some over hang.

Starter Set

Above is what I started with and over time I will find out which shapes work well, which don't... might have to use some PVC to get different radius sizes, or make a few new shapes.  In the end if this doesn't work well then I'll really respect the Perma-Grit tools if I buy them.

Section 12

I had a bit of analysis to paralysis on this section and spent a few weeks just preparing for the fiberglass work.  I don't know if it's intentional but it seems you start off small in this section and then ramp up to some major fiberglass work when dealing with the canopy, doors, ect. I suppose it's just another evolution in the building process where you encounter something new and have to work through the learning curve and in the end become somewhat competent in the process.

So after reading, watching videos and talking to some EAA members about Fiberglass work, the concept isn't overly complicated- you take resin, mix in some hardener... put it over some glass clothe and then magic happens. After this research I was able to put in my initial material order and get started on mentally working through the steps and staring at the parts I needed to work with.  I had some concerns about what to trim and what not to trim... really just to get an overall idea of what I was supposed to be doing.

The first steps though in this section though deal only with trimming of some pieces.  They lay out an exact specification on flange measurements and using a band saw and newly made tools I was able to get them to fit rather well.

After getting them placed in you match drill everything first with #40, then with a #30... clecoing as you go to ensure it stays in place.  You do this for the HS ends as well as rudder top and bottom.

Rudder top

After countersinking the fiberglass and dimpling the aluminium it comes time to secure it in place.  This is done with cherry (pop) rivets which is fairly simple.  I was extremely happy with the results for two reasons- 1) I became comfortable with sanding and trimming fiber glass pieces. 2) The gaps between the elevator counterbalance arms that I worried about so much during hanging seemed to close up a bit.

1/8th or so gap now

 For the bottom piece of the rudder I wanted to do something a little bit different.  This piece will eventually have a light installed and I don't want to drill out rivets each time I need to mess with it.  So what I ended up doing is installing some nutplates so I could use stainless steel screws to attach it.  May have added 30 mins and $20 dollars to the project.  Really the only thing you need to do different is match drill the fiber and skin to a #28 to accommodate the #6 screws I used and then dimple and countersink using the #6 dies and bits.  I also plan on doing this to the forward fairing on the top of the horizontal stabilizer so I can add a camera or something in that later.

Nutplate modification

Top horizontal Stabilizer

 The forward fairing and rudder parts are where you get into actually messing with fiberglass and epoxy.  After trimming and match drilling the pieces as before you'll need to do some additional trimming on the forward HS pieces to allow the elevator counterbalance arms to clear it by at least 1/8".

Untrimmed

Trimmed

 I've read about people using foam or wood as a backing to the pieces to lay fiberglass.  I tried something different and used clay backed by wood, wrapped in foil... now in hind sight I think foam would of worked better but went with clay to include my art loving kid in the process.

Evolution of the molds

Finally it was time to tackle the fiberglass process.  One thing great about fiberglass if you mess something up, you can cut it out or otherwise remove it and do it over.  I actually had done this at least once while I was learning the process of how resin cures, or over pulling the cloth or in some way shape or form mess it up.  I also experimented with some dark pigment in the resin to give it some color.  Did a number of things but in the end ended up with a decent start on the pieces.

As I type this I'm currently curing the a 'lay up' of fiberglass on the inside.  After this cures enough to be worked with I can put on the final layer inside and allow that to cure for a few days before finishing up some cosmetics on the pieces.

Empennage Attach

Section 11

Project Punch List

If you've ever worked on a project you more than likely have used a project punch list.  It's literally a list of items that need to be resolved prior to project completion.  It's different than a plan because it's more reactive in nature and will vary throughout different phases.  This project comes with the plans and it's up to the builder to resolve and plan out some of the other items such as interior, avionics, lighting, engine ect.  I track that on a spreadsheet just tossing down ideas as I think of them or track parts, prices, ect.  But post EAA Tech Counselor visit it was apparent I needed to start up a list to track various items needing to be completed or fixed.  Even though I work in IT I'm very non-technical about my list creation and I use paper and a pen.  I used to try to get fancy at work with lists but I always reverted back to a pen and pad.  So that's what I'm doing now, using a list and marking off items as I complete them and if it gets too messy with notes I'll transcribe it to a new piece of paper.

Attachment

Going into this process it seemed fairly straight forward however it was anything but that.  I tracked my time but I can't tell you what I spent on the actual attachment steps, or what I spent fixing mistakes or working through my punch list.  I also didn't take a lot of step by step pictures because I would work sporadically on things as well as jumped around to various steps as I waiting to fix certain things.

I spent some time working through the previous punch list items as well as new ones that I found. For example for whatever reason I forgot two rivets on the HS Spar... easy fix but strange I missed them. I did the deburring of parts that I had missed or that were still a bit rough on the edges.  I went over each bolt that was permanent and ensure proper torque and marked accordingly. There were a number of rivets that I had put off fixing until now.  I had used a few of those 'Oops Rivets' which I recently ordered and they worked out great.  In one particular case I had to use a wood block and hammer to level out the skins before using the new rivets.  It's not the prettiest but looks much better and after paint won't be noticeable... plus it's on the bottom of the tailcone.

Elevators Attach

I had watched some videos of this process and the consensus what it's a bit of a pain.  You have to put them on, test fit, take them off, adjust, back on... ect.  It took me an extreme amount of time because I was chasing perfection.  The important part is you don't have binding and it's free to move up and down without rubbing or hitting anything.  There's also an aspect where you want to hang them so on the outboard HS edge and the inboard Counterbalance arm there is an even 1/8th inch gap.  This ends up looking somewhat like the picture below.

The problem is in this picture the right side is an 1/8th but the left side is 1/4th.  It was even worse on the right elevator with it about 3/8ths gap on the forward end.  This drove me crazy and I must of spent a good 4 hours putting these on and taking them off 70 or so times.

I finally got it to a point that I was happy with and decided to move forward.  The next step is to get the trailing edged even and they suggest using duct tape... I did that and also used a clamp on a specific rivet location (5th in) to keep it level.  Then you methodically remove the right elevator (again!) and match drill the left horn using a bushing that Vans provides... now like most I had to use a file to reduce it enough to fit but was easy enough.  After that you take the left elevator off and put the right one back on and drill that side.  Then you put everything together, lock the trailing edges and then using a wood block you made drill the bottom of the horns evenly.  There's an entire process to this to help ensure everything straight so it takes some time.

After working through all that you can once again check the clearances to make sure you have 35 degrees up and 25 degrees down.  All was well and decided to go to bed.

Well.... something was bugging me as I laid there in bed.  Grabbed my IPad and started some further research.  My main concerns were that if my counterweight arms were bent or warped and I was using that as the primary measurement then that would affect how each elevator was hanging.  The other concern was if they are uneven then that would affect the way it flies... which is bad.

After reading about some methods people used I decided to essentially start from scratch at midnight... after about an hour I had determined that I had the rod end bearing bolts on the inboard side too far out therefore compromising their strength and that indeed there was some unevenness on my counterweight arms.  I made a post on the Vans forum with some pictures of my concerns and findings.  The short version is you want to ensure your brackets on the HS Spar are straight (Look through them) and you don't want to deviate too much from the rod endbearings initial 7/8th inch positions and both elevators should be even.  Turns out my main concern with that 1/4" gap on the forward end of the counterweight arm is a non issue.  Per Vans it's there more to provide clearance to prevent ice build up if you get into those conditions... which as a pilot is a bad bad thing.

So I did three things to resolve this.  First I made a tool to make it easier to install and adjust the rod end bearing bolts.  I took an old socket and notched out the ends which worked out fine.  I've seen other people do it with PVC or you can buy a tool as well.

Next using the method I put on the Vans post I rehung and adjusted the elevators... Truth be told I found myself randomly walking out to the garage and readjusting a number of times over the course of a few days. The end result though I'm happy with, they're even, move unbound and there's no more than a 1/4" gap on the forward part.

The last and most challenging thing was to get the extra holes on the horn welded in.  I got the information of someone who was able to help me get it welded... I did the grinding and he did the welding and turned out great.  Come to find out he's done a similar fix on someone else RV in the past.  I didn't take any pictures of the process, just wanted to work through it.  After they were welding and cleaned up I was able to redrill the holes in their new places following the same steps as before.  This time after I removed them I had to reprime and topcoat each horn since I grinded off a lot of the powder coating.  I'm not sure how prone these are to rust but if anything it was done more for aesthetics.

Redrilled and Primed

Rattle can white

Parts and Prime

I did a number of things out of order in this section. With my elevator horns messed up that sort of threw the linear aspect of the build off a bit. So not to just wait I jumped around and started making the brackets required for the HS mount and elevator trim set up.  It really helped out that the pictures in the plans were to scale so I was able to complete a piece, check it against the drawing.  I'm not sure what people use to get their parts looking like they were done with a CNC machine but mine are more of an artisan 'build a plane in your garage' type pieces.  I use a chop saw with a metal cutting blade, a band saw and a grinder.  It gets the job done but again not every piece is perfect for example on the HS shims one side of each is more rounded than straight.

HS Shim

Trim brackets

Trim cable brackets

Working out of order there were a number of other parts I deburred, drilled and cleaned so I could prime everything at once. It included the control arm that connects the elevators to the bell crank assembly, the elevator trim housing and some other minor pieces.  Using the last of my AKZO I primed everything, including the inside of the control rod.

Horizontal / Vertical Stabilizer Attach

This process was very straight forward per the plans.  In essence you line everything up according to a rivet point on the tailcone and ensure it's equal in distance.  You use a wood block to help keep it in place and then match drill.  Since this was the area where I added some additional depth to the bracket I ordered some longer AN bolts to use.

Likewise the Vertical Stabilizer was straight forward to attach.  Had to do some match drilling, it's also where I noticed I was missing two rivets... anyhow all fairly simple with the hardest part being that you have to fit your arm in a small space to get to certain bolts. There is a step to apple Anti Seize paste which may not really be needed now but for fun I applied it anyway.

Once you get to the step above you take everything back apart to deburr and clean up the pieces in preparation for putting it all back together.

Elevator / Rudder Attachment

Since you previously drilled and test fitting everything this step is a complete non-factor.  The only added challenge is getting your hand in the space under the VS to put the bolt, washers and nut on.

Likewise you have to have equally small hands to attach the rudder.  The good news is unlike the Elevators the Rudder went on without much adjustment. Took me about 4 tries to get it positioned correctly where when measured per plans was fairly accurate.  Final fit and measure can happen during rigging.

Elevator Trim and Control Rod

There are two components that need to be built in this section.  One is the control rod which is fairly straight forward.  Takes a bit because you need to prime the inside of it and give it time to cure completely before putting the ends on.  And with all my pieces in the tailcone I painted them as well.  Connecting it was straight forward but required you to make a wood triangle to position the bell crank in a particular position.  That coupled with locking the elevators in the trialing positions guides you to how much you have to adjust the control rod bearings.

The elevator trim actuator assemble takes a bit more time. Mine came out fairly tight taking a bit of force to make it move.  However once I hooked up the motor it really functioned fairly smooth when I hooked a 9 volt battery to it.

I bolted it in place in the tailcone but didn't run the cables to the trim tab.  Knowing at some point I'll be removing the elevators I will leave connecting this all together at a much later date.

This concludes the attachment section and will need to do a bit of reading before attempting the next section which deals with fiberglass.

EAA Technical Counselor

This year is off to a fantastic start!  Today was the first of what I hope to be many visits from an official EAA Technical Counselor.  I don't know if I'm lucky or if it's pretty standard fare but I was fortunate enough to have a total of three Technical Counselors show up.  I was extremely impressed with the experience and depth of knowledge these gentleman had.  Definitely a resource you should utilize when building your first, or even fifth plane.

The visit lasted about an hour and a half and included some official paperwork.  The rest of the time was going over the pieces and answering any questions that I had.  The most important thing was they said I am doing a good job and there were no major issues.  Here's are some items and pictures that may help someone on their build.

Riveting

Okay when it comes to riveting I am my own worst critic.  It's just not perfect and I want it to be perfect.  So when it's not perfect it bothers me, it really really bothers me.  My friends can look at it and say "Hey that looks great!", I look at it and I see all the little issues I know about because I did them.  They assured me this is completely normal, gave me some direction on how to improve a few of them and we talked about some of the techniques that show plane builders use to make thing 'perfect'.  In my case it's going to involve primer and paint in a few years.

Deburring

There are some areas on the skins that weren't deburred as well as they could of been.  My method was to debur enough that you wouldn't get cut.  Some of these hard to reach places just involve running a file over it a few times followed by a scotch brite pad and calling it a day.  I didn't do that well enough or missed a few areas.  For example in the picture below you can see it's had a pad ran over it but you can visually see it's rough.  I'm going to spend an hour or so and get these all cleaned up.

Cracks

Might a tad hard to see in the picture but I had a small crack in the skin.  This is what happens when you hit it with a wrench while taking on and off the elevators 30 times.  It's a tiny crack but if ignored can turn into a much larger crack similar to what happens when a rock hit your windshield.  The fix, oddly enough is the same as what you do with a windshield. 

To fix this I'm going to drill a 1/64th or so hole at the edge of the crack.  This will keep it from getting larger and then I'm going fill the spot in with some JB Weld.  Luckily I'm a pro with JB Weld so will not need any further instruction on that.

Bolts and Torquing

Over or under torquing bolts is/was a concern for me.  I have a pretty good torque wrench but new to such precision bolts I wanted to make sure I was doing it correctly.  What I learned is you find out the torque required to turn the nylon threaded nut and add that to the value.  So these AN3 bolts require 20-25 in lbs torque.  If the nut takes say 2 lbs of pressure to start turning then the range will be 22-27 in lbs.  So before I mark these I'm going to loosen them a bit redo them.  Not a ton of them so shouldn't take long and moving forward I know how to do it correctly.

Also the area where I added the additional 1/16th or so spacer needs the bolts replaced.  I up sized the rivets but used the bolts called out in the plans.  As you can see by the picture it's too shallow as you need a thread and a half at least clearance on the bolt.

Advisory Circular(AC) 43.13

Pilots know what an AC is and most will know that 43 deals with maintenance.  What I didn't know was AC 43.13 is a 646 page document that covers all sorts of building techniques. Specifically it's 'Acceptable Methods, techniques, and practices - Aircraft Inspection and Repair' . I went ahead and downloaded a copy and will start referencing it first when I have a question or need a better understanding of something.

In closing I can't stress enough how important it is to involve your local EAA Chapter on a build.  They're there for the same reason you're building a plane in your garage, a passion for aviation.  The reassurance you get that you're on the right track is priceless and having a team who wants to help you succeed in your project is also priceless.