Wed Dec 28th - nose fairings

Time to catch up on what's been happening.

I've been doing a lot of work on the project, but haven't had time to post anything.

 I'm going to break the wheel pants and fairings into a couple of posts.

Once I had the gear and wheels installed, I decided to go ahead and do the wheel pants and fairings.

I started with the nose wheel. I don't know if there is a really great (or better) way to approach this, but this is what I did.

After doing a couple of pants I got better at it, but for the first one (the nose wheel pant in my case) I really snuck up on the fit which means it took a lot of trial and error, just making very minor trim adjustments as I went.

I started by opening up the large wheel opening first.  This was my first cut at trying to find a way to securely hold the wheel pant while I trimmed it.  In my case most of the time I used my jig saw with a fine tooth blade.  It makes a nice clean cut and is pretty easy to control.

Later on I came up with a more secure system using  a couple of 2x4's screwed to the bench that were a tight fit inside the pant.  By clamping to those I was able to get at the fairing very easily and it was held very securely.

I didn't realize at first how much I was going to have to enlarge the hole.  It ends up needing quite a lot of clearance to give adequate (I'm using a finger width) gap between the wheel and the pant.



Here's the first time I could actually get the pant onto the wheel enough that it sort of fit.  At this point the forward piece has not been trimmed.  It need to be relieved around the gear leg before it will mate up with the aft part.



Starting to trim the forward part just to get a sense of fit and so I could drill it to the aft fairing.



Forward has been trimmed enough that I can fit the leg fairing.  That's important so I can get the length down and also so the closure for the cowling can be fabricated.

Notice you can see my car jack under the nose.  I used my old stands with my floor jack and a large 2x6 to jack the wheel up until there was no weight on it.  That's how the plans specify to fit it.  Obviously it also needs to be large enough to handle any wheel expansion from landing forces or a/c weight, but it does make it easier to work on.



Much better fit at this point.



Starting to lay out the holes for the nut plates that will attach the fairing to the wheel.



Getting ready to drill the cowl support to the engine mount.  Very tight fit.  I used cleo clamps to hold it in position so I could get it where I wanted it before I drilled it.



Another shot of it clamped before drilling.



The more or less completed lower cowl bracket.



Checking the leg fairing fit to the lower cowl bracket.



Lower cowl bracket in place with pins.




Trimming the gear leg fairing to fit the lower cowl bracket.



Installing the nut plates.

Sunday, November 6th main and nose gear, wheels, brakes, etc

I got tired of working on the windshield and cowling, so I decided it was finally time to the gear installed.  I've had the fuse sitting on a fairly large frame was basically some short homemade sawhorses with moving dollies underneath.  One frame was forward under the firewall, and the other was under the main spar.

The working height was set to make it easy for me to stand outside and reach in, but that wasn't high enough to allow inserting either the mains or the nose gear.

My plan was to raise the fuse by alternately lifting the fuse so I could shim the aft support, then using that as a lever to raise the forward fuse so I could shim the forward support. By alternately working forward and aft and using some 2 x 6's I had, I was able to raise the whole fuse about 4", which gave enough clearance to install the main gear legs.

The thin stuff on top is some 1" pink foam insulation from the hardware store.  I was also using that as a support when I pushed on the aft fuselage from below to lift it high enough to slide in the shims.



Forward shims.  At this point I was high enough to get the gear leg in, as you can just see in the upper right corner of the picture.



Gear legs being installed.  I did have to shim it a bit higher after this to give me space to put the wheels on.



The axle had to be polished a bit. No corrosion since I've had it stored in my shop which is dry and clean, but there was something on the surface (protectant) that I needed to polish off so the inner mount and bearings would slide on.



Parts out and ready to start assembly.  The wheels and brakes that came with the kit are Matco single piston units.  Ken Stitt told me he was very disappointed with the braking performance on his RV-7 and switched to Grove dual piston units.  My A/C is a bit lighter and a bit slower, so I'll give these a try.  The Groves are a simple upgrade if these don't work like I want.




Starting to assemble the wheel.



Brake caliper.  Took me a while to figure out how all the bits went together.



The inboard support bracket needed to be reamed - there was powder coating in the hole and it was a tiny bit undersize.  I also had to run crocus cloth through the through hole in the axle to get the bolt to slide into place.



Everything assembled.  I don't know if these brakes are different than the originals specified on the plans, but I had to remove some material from the wheel pant bracket to allow clearance for the upper arm of the brake caliper unit.



Axle bolts.  The come pre drilled for cotter pins and also have the nutplate already installed to provide a place to mount the outboard wheel pant support bracket.



Installed and ready to go.  Once it's torqued, you need to drill the axle for the cotter pin.




Starting on the nose gear mount.  I didn't think to ream this hole out when I installed the motor mount, so I had to get creative trying to enlarge it enough to get the bolt in.  I couldn't get any sort of drill in there (even an angle drill), so I used my drill bit and a pair of vise grips to enlarge it by hand.  Worked surprisingly well.



Bearings for the nose wheel prior to packing.  I just pack them by hand.

I asked Nick what kind of grease to use and he told me he uses high quality marine grease to resist corrosion, so I followed his lead.  We'll see how well that works.



Nose wheel before installing the tire.




And here is a shot of how everything goes together.




Nose gear fork installed below the upper limit stop.  There are two holes on the upper side of the yoke that will receive a pair of allen screws that provide the limit stop action.  They allow the gear to rotate to about a 90 degree angle, but no further.





Everything more or less assembled.  I still hadn't set the breakout force on the yoke yet because I didn't have a spring scale at the time.  I did that yesterday afternoon after picking up a scale.



Starting to look like an actual airplane.

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.