War Paint on the Rudder

After a long few days of prep and paint, the rudder is finally covered in war paint.  The rudder on the left is mine, and the one on the right is on a flying Sopwith.  The paint took a few days because between each coat of each color I had to let it dry.  I would work fifteen minutes at a time towards the end.

 

I did the white stripe first, figuring that would be the easiest to cover if there was a mistake.  I set up a makeshift paint booth in my garage and used the spray gun for the first coat.

 

 

 

Overall, I wasn't too happy with the spray gun, so I switched to rollers. Several other builders rolled their paint on aircraft that are flying and have no issues, and rolling takes about 1/10th as much time in cleaning and prep, so that seems to be the way to go.   I used simple 4" high density foam rollers from the aviation department at Lowe's, the same place I picked up the paint.  Side rant:  When did paint get so bloody expensive?  Seems like it has tripled since the last time I painted...

 

Here is the white stripe after the second coat and the masking tape was pulled.  One thing I noticed was there was some bleed that I didn't like.  I think the spray gun was part of the problem. For the next two rolled colors I had much more success, but I also made sure to keep the tape lines at the top as I painted to allow gravity to help, so that might have been the major factor in the better lines.

 

 

Coat one of the red paint for the tip. hanging the rudder so I could rotate it to get at the edges was a big help.

 

 

Second coat of red and, when the tape was pulled, I was much happier with the line. 

 

 

Next, the first coat of blue.  I had to use a brush to get all the nooks and crannies on this stripe, particularly around the control horn.

 

 

Using a pile of shop towels and a clamp I then hung the rudder to dry so that the blue paint would be pulled away from the paint line.

 

 

The second coat of blue, then the tape was pulled to reveal the final product.

 

Tomorrow, spraying two clear coats over the rudder and she is all done.

 

 

Practice Build Time = 5.5 Hours

 

Final Fabric Shrink and Primer

It's looking good!  As the rudder is almost ready for paint I am pleasantly surprised with the results at this point.

First thing before the final heat shrink of the fabric, I picked up a basic full-size iron from Target.  The small hobby iron I had worked great for small lines, curves, and tape, but it would loose heat quickly and was very lightweight.  This one worked great, held heat well, and had a bit of weight to let the iron do the work when shrinking.  I used my infrared thermometer to get exact dial points for 250, 300, and 350 degrees (the white paint marks on the dial).  The iron worked well and held its temperature within +-4 degrees.  I looked a while for an iron without auto shutoff, but it wasn't a problem with this one.  It had a red light that would flash when in auto shutoff mode, so you will see it and know the iron needs to heat up again.  Plus, it only took about 60 seconds from cold to full heat.

 



I started with the iron at 250, working the tapes and seams in an alternating pattern to avoid distortion while the fabric shrinks.  Then, I worked the open fabric in the same manner, letting the weight of the iron do the work as it slowly slid along.  The results were positive with wrinkles shrinking up, glue bonding stronger, and the fabric tightening up.  After a cooling period, I repeated the process with the iron at 300, then after another cooling period did it all again for the final shrink at 350.  The tightness of the finished fabric turned out very strong.

Finally time for paint!  The primer process using Stewart Systems EkoFill uses three coats applied in a certain manner as a primer and UV blocker. The first coat and the second coat are applied in opposing directions.  I put the first coat on with a foam brush from front to back, taking care to use even strokes and getting a good full coverage.

Once the first coat was dry, I lightly ran over the surface with a 320 grit sanding sponge to try and take out any minor bumps and imperfections.

 

 

Then, the second coat of primer.  This one using a foam brush as well, but applied in the opposite direction.

 

Tomorrow, once it is dry, I'm going to apply the third primer coat with the spray gun, then it will be time to paint and finish this thing.

 

Practice Build Time = 2 Hours

Finishing Tape

Now that the fabric has set, it's time for the finishing tape.  I cut out 2" strips of fabric to use as tape for the rib seams with the pinker after tracing out the strips with a pencil.  I figured for this practice rudder there was no need to order a roll of tape and the spare fabric could get me by.  They turned out nice and straight with clean pinked edges.

 

A quick sizing and pinking the edges for a precise fit and they are ready to glue down.

Per the suggestion of the fabric system manufacturer, I started by gluing about a two inch square on the wing fabric, then placing the leading edge of the strip over the glue patch while wet.  I pressed in the strip, then brushed glue on top.  While wet, I wiped the glue with a shop towel to help press in the glue and to clean off any glue ridges that would show through finish.  I repeated for the rest of the rib tape strips, then let dry.  This gave a good base to work with that allowed be to tug the strip straight as I worked it later.

Once the tip was dry, I finished the tape with the same process as the initial spot.

I let that dry, then worked the other side of the rudder  in the same manner.

Next was the finishing tape for the rudder bow.  I use 3" Bias Dacron tape for the bow because I wanted something that could stretch out the wrinkles around the curve.  Turns out that was a good choice.  I started by tracing clean glue line with a pencil around both sides of the bow.

Just like the rib tape, I started with a glue patch on the top edge of the bow, then let it dry as an anchor while working the bow tape. Again, using a shop towel to clean off the excess glue while wet.

I worked out the wrinkles while working the tape around the bow.  The bias tape worked well and with a little tugging along the way the wrinkles were not a problem.

 

Once finished, the tape looked decent enough.  Time to let it all dry fully, then do the final shrink of the fabric.

Practice Build Time = 2 hours

 

Fabric on!

If you plan on building an airplane, plan on doing a lot of research.  Fabric covering an aircraft is a complex process and will take a great deal of research to figure out, as I can confirm after this past week.  Fortunately, there are great resources out there such as walkthrough videos on the covering process and manuals that detail every possible step.  Finally felling ready, albeit apprehensive, the fabric hit the rudder today.

The first step was to prepare the ribs for rivets.  To attach fabric to a control surface, you need to attach it at regular intervals with one of three generally used methods: stitching, rivets, or screws.  After consulting with several builders and learning the kit suppliers recommendations, I decided to go with the same 1/8" stainless steel rivets that I am using on the aircraft structure at 4" intervals along each rib.  If you choose rivets, then the first step to covering is drilling, deburring, and cleaning the holes for the rivets.  Two things learned here: (1) order a bulk pack of the drill bit you use most, in my case the #30 bit for the 1/8" rivets, because drill bits break and it really is frustrating to have to stop work because you don't have a spare bit; and (2) a good deburring tool (like this one I picked up from Aircraft Tool Supply) will really make the work quicker and cleaner.

 

Now, with the rivet holes in place, I went over the rudder with 220 sandpaper again to make sure I didn't have and areas that would tear the fabric.  After running a clean rag over all the surfaces and making sure there were no snags, it was time for tape.

 

 

I used cloth tape from Aircraft Spruce to cover all the rivets and metal edges in what turned out to be a more tedious process than expected.  The kit manufacturer says you can get cloth medical tape from a drug store which seems like it would work better as it feels like it has more tack to the glue.  This tape required a lot of pressure and time to bond to the frame. 

 

 

I tried diligently to keep the tape free of wrinkles and finally used an awl to punch holes in the tape at the rivet holes in the ribs.

 

Another thing I wish I would have done differently: the screws holding the bottom of the frame and the middle rib to the spar should probably have been countersunk a bit more.  They protrude out slightly and if they were a bit more flush the project would look cleaner.

 

 

Next, I took the 2.7 oz Dacron Fabric and traced out the rudder with about a 6" overlap.  On the second side, it worked a lot cleaner when I trimmed and clamped the fabric over the spar and then traced out the 1" overlap as suggested by the Stewart System videos.  However, for this first try I'm glad I left some extra fabric to trim as I needed to correct a cutting error.

 

To cut the fabric, I used another cool tool, the Florian Pinker.  It cuts a pinked diamond-shaped edge on the fabric continuously as it rolls along.  The pinked edge is supposed to prevent the fabric from fraying and supposedly ads to the adhesion strength when glued.

 

 

Up next, applying the glue, EkoBond, to the rudder.  That the teal colored stuff on the picture. Per the instructions, I applied a full layer of glue around all contact edges and let dry.  It only took about 15 minutes to dry to a tacky surface that was ready for fabric.

 

 

Starting the process of hand tacking the fabric to the glue was another difficult task as I was constantly adjusting the fabric and trying to keep it straight and lined up.  With this glue, you can get a nice temporary tack by just using hand pressure, and can simply pull it off and re-tack it with a little pressure if you need to as you go.  That helps to hold things in place until you apply the head to get a firmer tack, and allows for error correction.

 

 

Working very slowly, I used my small hobby iron at 230 degrees to tack fabric to the frame, taking care to try and be as smooth as possible on the rounded edges.  When it was all done, while the heat did take out most of the wrinkles, there were a few left.  Hopefully the final shrinks of the fabric and the final heat process will clear those up.  By far, the most difficult portion was the corners where you have to trim and fold them just right. 

 

After the whole frame was tacked, I passed the iron around the tubes on the inside to seal the fabric overlap.  Honestly, I was greatly relieved to see things look cleaner at this point. I was worried that it wouldn't bond or look right until now.  But, seeing the fabric start to adhere smoothly gave some confidence.  I was still worried though, as the fabric was quite loose.  I thought I have maybe left too much slack in the fabric and would have to redo it all.

 

 

I took the iron over the fabric at 230 degrees for the first shrink and wow!  it tightened up and started to look like a real control surface! I was impressed this far. After that, I trimmed out the second panel of fabric, this time using clamps to hold it at the base of the spar while I measured for the 1" overlap.  This time there was no room for excess trimming, so that saved time.

 

 

This panel took only a few minutes to get right, much quicker than the first one.  It is always a good feeling to get better and faster at a task.

Another layer of EkoBond glue around the fabric covered frame, this time carefully wiping away the excess with a shop towel and working hard to keep a clean and even line for the next panel to adhere to.

 

Same thing on the other side, and we are ready for panel #2.

 

 

 

Second panel is on, again carefully working to keep wrinkles out of the curved edge.  This time, I was not as successful at that task.  Hopefully the finishing tape will hide those imperfections.  A pass with the iron for the first shrink and it looks pretty good though!

 

 

Remember those rivet holes?  Over the top of the ribs I applied a strip of 1/2" reinforcing tape, then punched a hole with the awl at the rivet holes.  I then took the drill, set on a very slow speed with a #31 bit, one size smaller than the hole, and ran it through the hole to allow the rivets to be pushed in.  The rivets took a little force, but the slid into place and were easily pulled solid with the air rivet gun.

So far so good!  It looks like a rudder!

At this point, I've been at it for about 4 hours, so it was time for one last task before I called it a day.  I find that I start to rush things and quality suffers after about 4 hours straight, so I'm trying to prevent that.  The last project of the day was a reinforcing patch over the slit in the fabric for the control horn.  I cut out a 10" x 5" rectangle with the pinking shears, then a pinked cut in the middle for the horn to pass through.

I glued the patch area of the fabric, let it dry, then heat-sealed the patch in place.  Hopefully this patch will make the fabric strong and durable here so no tears will form at the control horn cut.

That's it for today!  Next is the finishing tape, then on to primer and painting.

Practice Build Time:  4.5 hours

Rudder Ready for Covering

Today started, per usual, with me learning that I probably should have done things in a different order.  I took the freshly machined control horn and started scoring the holes on the rudder spar and rib for the control horn bolts, but soon realized that securing the nut underneath the gusset already riveted in was going to be difficult.  Next time, I'll have to wait to rivet in the gusset until after the control horn.  This will allow clean access to the nut and will allow me to line up the rivets on the gusset so they don't interfere with the bolt, two of the problems I had today. 

 

After scoring for the holes, another problem emerged:  My drill was too large to give me a straight angle to drill into the rudder rib. So, off to Harbor Freight again where I picked up this pneumatic angle drill.  I intended on getting the electric one, but they were out of stock and the shop is set up for air, so for $27 after coupon this one did the trick. 

 

 

The bolt holes were drilled out with a #11 bit and I really liked the air drill, it allowed for good bracing so the holes were clean and on point.  After a quick deburring the AN3-10A bolts were slid in place.  For the nut end under the gusset, I rigged up a thin wall 3/8" socket to a long extension bar so I cold hold it firm while ratcheting the other end.  That did the trick, but I didn't like the stress it placed on the gussets to get it in place.

 



 

After the control horn was bolted in, I started fabricating two angle braces that are not in the plans, but suggested to me by master builder Sam Buchanan who used them on his Fokker project.  I started off by cutting out two pieces, each 2" by 4", from the gusset thickness aluminum sheet, then bent a 90 degree bend with the metal brake right down the middle long ways.  Then, the pieces were traced out over the control horn to fit, sanded, smoothed and deburred, before the next step.

 

 

Two rivet holes were drilled using a #30 bit in the control horn and braces for each side, and one rivet hole for each side was drilled where the brace connects to the rudder spar.  After the deburring and locking in with Clecos, they looked smooth and strong, ready for rivets.

 

 

Once the stainless steel rivets were pulled, I was happy with the result.  The control horn fells strong and stable enough so that it can take the forces of taxi and braking.

 

 

 

With the practice rudder fully fabricated, it is next time to try my hand at covering.  I have to watch the covering video from Stewart Systems again and will be back at it soon.

 

Practice Build Time = 2.5 hours