Saturday, Oct 22nd cowl, windshield, mains, right wheel and brake

Since it will take a while to get the windshield to a point where I'm not embarrassed about it (hopefully anyway - not great at glass work), I started working through the issues with the cowl.

There are a couple of things I need to fix.  On the passenger side, there is a fairly large "underbite" so that the lower cowl is nearly 1/4" shorter than the upper.  I did a lot of googling and thinking about it and decided the best solution was just to lay up a layer of micro and sand it to the shape I need to bring it in line with the upper cowl, then sand it slightly undersize and glass over it to give it the strength it needs.

Here's an old shot that shows what it looked like before.

The upper cowl is about 1/4" to 5/32" longer.  I considered several options including cutting the cowl and extending it out.  After a lot of thought I decided to just shim it out with filler (mostly flox) and glassing over it.   That seemed like the best way for me to have a shot at it coming out looking pretty reasonable.
 


I filled it out until it was oversize, then sanded it down so it was just undersized, and then glassed it over.  I also reinforced the inner edge where it was a bit thin and built up the flange a bit where it was too short.




The inner flanges on either side of the propeller don't fit very well.  They are both a bit thin, and they also don't extend down evenly on either side and also don't extend to the flange, which is fine structurally but doesn't look particularly good.

I decided to extend the flange with flox and glass.  This is after extending it downward but prior to trimming.

I'll add some additional shots when I do the other side and start working on the cowl again.

Saturday Sept 23rd, more windscreen & cowling

After laying up the glass and pulling the slider back.  I have 4 plies along the forward edge (except 6 at the very center) and 5 over the top.  That's all 9 oz. bi direction glass.

It took me nearly an hour to open the canopy after I did all the layups and after waiting for them to cure.



I rough trimmed the top fairing so I wouldn't rip my hand up on the edges.  After I got this done I just had to sit in it a while.  Glad to have this almost behind me.



I'm pretty happy with the fit.  The seal seems to be nice and tight without binding.



While I was waiting for the last batch of Superfil to cure, I laid out the slot for the nose gear in the lower cowling and cut it out with my jig saw.  I cut it a bit short for starters.  I'll lengthen it if I need to.



I'm sure I'll be working on the windscreen fairing for the next couple of weeks.  Basically sand to the best shape I can, check for low spots, fill them, sand, rinse & repeat until you're satisfied.



In between working on the fairing I've been working on getting the cowling fit.  Before I riveted the hinges, the hinges and hinge pins worked great.  After riveting, I could hardly get the right side or the right upper in.  The fit on the right was so tight I was using a drill to help and it was nearly hanging up.

I put the cowling together off the airframe and discovered that about 5 or 6 inches of hinge was offset very slightly just aft of forward.  That one area was causing all the binding.

I drilled it out, moved it a bit, and then re-riveted it.  Goes in great now.

Here I'm doing the same thing to the upper cowl where it attaches to the firewall.  I actually ended up moving about a 6 to 8 inch long section very slightly aft.  Once I did that the upper pins went in very easily as well.

I just filled the holes with flox.



Working on a hinge clip to prevent it moving.  I made this from a piece of scrap J channel.  I'll rivet one on each side of the firewall.  I plan to do something similar for the upper hinge pins, except I'll rivet those to the cowling rather than the firewall.



Over the next few weeks I'll be working on the cowling to get it cleaned up as well as working on the nose gear slot.  Obviously I have quite a bit more filling and sanding to do to the windscreen before it's ready to be called finished.  I'll work on that as I go.

Yesterday I created a punch list of items to be completed before inspection and first flight.  It's getting pretty short, although some of the things on the list will take more than a few hours to complete.  I've had a bunch of folks ask me when I think I'll be done, but having never done this before I honestly don't know.

Friday Sep 23rd, 2016 1 of 2 Windscreen, cowling, glare shield, etc.

After making a paper template for the glare shield, I trimmed the fabric I got from Cleveland and glued it down with 3M spray contact cement.  I used masks to keep the cement where I wanted it, and did half at a time starting at the middle and working out to the edge.  Glued down great.  Hopefully it will last a good long time.

I have a crimp edge that will give a nice rounded and softer edge to the aluminum, but I won't put it on until much later after I have the panel reinstalled and everything hooked up for the last time.



Once that was done I started working on figuring out exactly where the plexi was going to lay relative to the forward skin, vertically side to side, and fore and aft to determine where I would drill it and how large a gap would be appropriate between the slider frame and the windscreen.







I also had to work around the edges to determine where I would need to install small clips to pull the plexi down tight to the skins.  There were some small gaps in the center (maybe 1/16"), and a couple on either side.




The sides right at the roll bar were interesting to fit.  The left (pilot side) particularly really needed to be pulled down some, but I didn't want to install a rivet or add another screw at that location.




The right side was better, and I was able to just pull it down with a couple of clips installed fairly far aft along the edge.





I wanted  a foolproof way to create a nice even line to use as my fairing edge.  I ended up using a piece of scrap with a hole drilled in it.  By inserting a fine point sharpie through the hole and sliding the bent edge along the cut edge of the plexi I was able to mark a nice even line all the way around the windscreen.  I put several layers of black 3M electrical tape along that line to provide a non-stick surface to work to when laying up the epoxy and later adding filler.



This is how I used the template to mark the tape line.  The grey tape above is some stuff Joe @ Van's told me about.  It's a wide (2") electrical binding tape sold at HD & Lowe's.  Epoxy won't stick to it either.  It won't quite wrap around corners like the black stuff does, but it's a lot less expensive and you can put in wide swaths of non-stick area/protection very easily.  Once I had a double layer of black vinyl I extended the edge back about 4" with the binding tape.  This ended up working very well.



Starting to drill the windscreen to the roll bar.  At this point I've final installed the forward brace to ensure the roll bar is exactly in it's final position, and also final fit the canopy latch/lock.  Once it was drilled to #36, I tapped it for #6 screws.




Starting to install the clips along the bottom edge.  I did this *after* installing the screws to make sure things didn't shift.  I had it firmly taped down during both operations in any case, but I didn't want any movement once I started nailing down the location.




I had a lot of problems getting the forward bow of the slider and the roll bar exactly even all the way across.  Down the right side (from the center all the way to the right) it was easily within 1/32".  Very close.  About mid way down the left side there is a gap.  Maybe 3/32" at the worst, although the total length of mismatch is not more than 12 inches or so side to side.  At any rate I thought I would have either a big honking gap between my top fairing and the slider that I would have to do something with later.

I'm posting this after I did the actual work.  In practice, I was able to make it up with a couple of extra layers of glass and just allowing the fiberglass to naturally conform to the surface as I laid it up.

Along the slider, not only did I cover it with the electrical binding tape, but I also added about a 6" wide band of the cheap brown packing tape (some sort of plastic).  I knew from previous experience that epoxy absolutely will not stick to it, so I added that as a top layer to make sure I could get the canopy open again after curing.

I was a bit concerned that I might have some flow through of epoxy into the gap between the two, but it ended up not being an issue at all.  I did do a prepreg layup for the first coat, so it was already wet out when I put the fiberglass on, and all I did was paint the plexi with a thin coat to make sure there was a good bond between the plexi and the glass.




Holes are drilled and I'm getting ready to tap them.




Once the screws were installed, I installed the clips and started sanding the aluminum and plexi to make sure the epoxy would bond well.




I made the clips as small as possible, then dimpled the clip and skin and riveted it on with some countersunk blind rivets.  I still had more sanding to do at this point as you can see the plexi still has some glossy spots.

N.B.  I had bonding issues with the first layup across the top and had to do the whole thing over.  I think this area here was done with some pro grade (blue) 80 grit.  After the bonding problems I did a lot of testing with scrap plexi and sample layups.  I eventually went to an aggressive 60 grit followed by 36 grit, which fixed the problem.

One note - although I had some issues with trying to get epoxy (west systems 205) & fiberglass to stick to the plexi, the one thing that stuck like crazy was superfil.  I'm not sure what's in it, but it stuck to everything I put it on like a leech.




Lousy picture - these are the two front clips riveted on.



Side clips for the left side.  As I mentioned, there was a pretty large gap right where the plexi comes down along the roll bar.  what I did was put a clamp there to hold it down tight, which, along with the clips, gave me a tight fit along the bottom edge.  I used my micro mix to glue the windscreen down along that line to within a couple of inches of the roll bar.

Once that was cured I was able to remove the clamp, and then apply filler along the rest of the edge to finish the attachment and provide a smooth even surface for the glass to attach to.



I first used dry micro to fill the gap.  I added black pigment to make it blend in so it wouldn't be so obvious from the inside.  (My original intention was to also apply several layers of black pigmented epoxy/glass over that, but given my later problem with the layup and my relative inexperience with glass in general, I opted to skip that step)

This is after several sandings and applying a layer of superfil.  Between the two clips in the center I still had quite a depression that I felt was too much for glass alone to deal with.  I masked off a small area with electrical tap and applied a thin strip of Superfil to raise it up a bit.  Later when I glassed it I put a small narrow strip of prepreg in this area prior to putting the glass over the gap.  That filled it in nicely.



Closeup of the aluminum roughed up and the line of micro dyed black.



This is after I applied that strip of Superfil to the gap and waiting for it to set up.



I did the same technique back on the pilots side to attach the plexi to the fuse prior to glassing.




Right side got the same treatment.




I'll do a second post since I have so many pictures.

Sunday, August 21st - Windscreen, roll bar handles, glare shield, etc

With the forward skin finally on and no reason to wait any longer, I decided it was time to tackle the windscreen. I need to get this done while it's still warm.

Before I did that I needed to mount the handles I got from Aircraft Extras, and put on the glare shield fabric I got from Cleaveland Tools.

I knew the handles needed to be angled down slightly to clear the slider frame, and I also knew I needed to mount them so they wouldn't interfere with the slider frame when it closed.

I sat inside and marked the roll bar from the inside with the slider closed, then used that line as the upper limit of the holes.

The handles are pretty beefy - 3/16 diameter, so I needed to drill two holes accurately aligned with each other (same angle from the horizontal in other words) and then drill holes for the screws in the opposite side that were #10.

I ended up making a simple jig using some PVC pipe that was almost exactly the same inside diameter as the outside of the roll bar.   What I was most worried about was that the holes would be aligned front to back.

 I used my drill press to drill through the PVC so the holes would be aligned, then split it in half with the band saw.  If I kept everything lined up and drilled in from either side I would be guaranteed to have everything line up.  Plastic isn't very durable, but it's only 4 holes.

Here's the guide.

    Marking the roll bar


I used the forward slider bow to draw a line on the roll bar, and then measured from the center out to make sure they were aligned side to side and the location made sense.

Lousy picture, but the upper line gave me a "go no higher than" limit for the top of the hole, and the thing that looks like a "P" is just a hand drawn location mark.





Guides clamped to the roll bar.  Once I had the one hole drilled I inserted just the end of the handle in the first hole, and used the far end as both a angle guide and location marker for the next hole.






So here's what it looks like after the pilot side is drilled.  Nice snug fit, everything lined up, and super sturdy.





And here is a shot of one side installed.  I used a 1" #10 screw, which fit full length and should make it plenty strong.



Inside view of the results.  Out of the way but plenty of clearance.  Works for me.


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Next on the list was to install the glare shield.  I wasn't sure what was appropriate to secure it to the aluminum, so I gave the mothership a call and talked to Joe.  Turned out he'd used the same 3M spray adhesive on his -6 years before and it worked great.  That was good enough for me.  I made up a trimming template out of shipping paper so I'd be able to trim it without waste.  I had a bit extra, but not so much I could really be very far out.

I just put the windscreen over the top, marked it, then worked the trim line back so it was clear of the windscreen by 1/4" or so.  I plan to use black dye in the micro mix and the first layups, so none of this will be visible from either the inside or outside.

Laying out the template for cutting.

August 5th, 2016 FAB airbox

I mostly finished up the airbox a couple of weeks ago but haven't posted any pics yet.

This is one of those things where I wish I was better at fabrication.  There is an awful lot of room for variation in the way you tackle this.  I'm pretty happy with how it came out, but I'm also pretty sure if I did it again I'd do a better job.  Functionally I think it will be great.  I'd have been a bit happier if it looked as nice as some of the jobs I've seen.

First I had to fit the flange/plate that bolts to the carb.  I had to do a lot of filing around the drain plug and accelerator pump housing to get it to fit right.



All the black marks are alignment lines.  Basically the carb doesn't sit centered and is slightly offset to the pilot's side, so the intake has to be angled back to the center to mate with the intake snout.  I spent a lot of time lining everything up with alignment lines and putting the cowl off and on over and over until I got it as straight as I could.  I then match drilled it to lock that in.


Below is a shot when match drilling the upper plate to the carb attach plate.





Once I had that done I felt comfortable trimming the filter. The plans call for cutting the filter first, but without having the plate in place and everything tightly held down I couldn't tell where to put it to trim it.

What I did was go ahead and mount the filter holders, then bolted everything up to the carb, and clamping the fiberglass box to the flange with cleco clamps.  That held the filter in place so I could see where to cut it and ensured everything was aligned properly.

Here's the trimming.  I did most of the trimming with my band saw and cleaned it up with a rotary cutter on the dremel and some metal shears.




I gooped up the carb with vaseline and filled the void with high temp black RTV. Forgot to take a picture, but after about 3 days of setting up it popped right off and is a great fit.

Here's a shot of what I said about lining up the snout with the intake. Takes a lot of fussing to get it all where you want.

This also told me how far the upper plate needed to be bent upward to align with the top of the intake.  That in turn allowed me to establish the lower limit with the fiberglass.  Basically it's just a lot of putting things on and taking them back off and measuring/marking until it looks good.
  

Once I had the filter right and had figured out where everything was going, it was time to match drill the fiberglass box to the flange.  I totally forgot that these were supposed to be an3 470 rivets instead of the -4s, so I drilled everything to #30.  Didn't realize my mistake until I started riveting.  Doesn't matter, but it's way stronger than it needs to be.





Here it is mostly assembled.  The angled pipe just above the forward part of the airbox is the carb heat fitting from Van's.  I bolted it on loosely so I could try various options to make sure it would align with the carb heat door, which was the next fabrication task.



I established the door shape with some really light scrap I had (.020).  I worked with that and some masking tape until I had all the angles and sizes established, then used it as a template to make the door out of the real material.  It's a fairly snug fit.

You can only move the door so far back due to the filter flange and the bend in the upper plate, and you can only go so far forward because you have to leave room for the hinges.




Getting ready to drill and rivet the forward upper plate to the airbox.  I left this till later to make sure I had a good fit with the door and so I could fine tune any height adjustment needed.





I did the foam insert in the intake snout twice.  The first time when I carved out the hole it was just a lousy fit, so I dug it all out, sanded it clean, and started over.

This is the second effort.  I tried to do a better job of fitting the foam precisely to the snout before I glued it in with the Bondo.

The oval dent on top is from where it fit into the snout, so it's a pretty good fit at this stage.



This is the forward side after it's been bonded in.  When cutting it out I used a spare hacksaw blade and left plenty of room around the edges.  I then slowly snuck up on the proper shape by just sanding the foam away.

I don't have a picture, but what I did was use spray adhesive to bond some 80 grit sandpaper to some scrap 1/2 round wood trim I had from working around the house.  It worked perfectly, and was a nice straight and stiff reference which was good for sneaking up on the fit I wanted.




This is the inside after bonding.  I just used Bondo as Van's suggested.  Worked very well.  Sets up really really fast.  You have maybe 5 minutes working time max.



This is the inside after cutting the hole and glassing it.  I used 4 plies of 9 oz. cloth.  I tried to use the ballon idea, but the epoxy was so slippery it just slid right out.  I ended up standing it up on end (on the back edge) and just pressed it out to the edges.

I had a good coating of epoxy on the foam to start, so it stuck pretty well once it started to set up.  I just used West Systems epoxy with the slow hardener.  Worked fine.

 


I found a shot of what it looked like before I glassed it but after all the final shaping and sanding.   Pretty happy with how it came out.