CANOPY March, 2005

Mar 2 - received my clay order from ArtMmolds.  I'd ordered both "medium" and "soft" Plastiline clay.  Boy, the medium is stiff as hell.  I can barely deform a golf ball sized chunk of it at room temperature.  It might be useful somewhere, but it's very stiff.  I can't imagine what the "stiff" is like - it must be very hard, for sculpting with metal tools.  Definitely get the "soft" if you order this stuff.   Spent some time cutting the clay up into manageable balls & stashed it in a coffee can.  A 2 pound block makes 10 golfball-sized pieces, and 20 balls just about fit into a 3 pound coffee can.  1.0 hr

Mar 3 - update web site  1.5 hr

Mar 4 - remove bubble from frame, prep for painting frame, mark paint line, lay out 3/4" masking tape along edge of paint line  0.75 hr

  Bevel the edge of where the WD716 and WD715 canopy frame weldments overlap.  The bubble rests against this, so it's best to not have an edge to create a stress riser in the plexi.  The white at the RT edge of the opening is part of the epoxy I put between the skin and frame

  Here, I put 3/4" making tape along the aft side of the line I drew, marking the fwd edge of the plexi.  This will give me a 3/4" unpainted strip aft of the fwd edge of the plexi, so the epoxy will have a place to stick.

Mar 5 - scuff & clean C702 skin top surface for primer prep.  I worked over 100 hours last week, and this week looks like a repeat, so not much time to work on the plane.  0.25 hr

  Scuff aft of the 3/4" masking tape.  This will be painted now.  I debated between using the gray spatter paint and flat black.  I decided on flat black.  Hope it ends up looking OK.  This need to be done before the bubble goes on, because it would be very difficult to spray paint in there with the bubble hovering above it.  The stuff in the background is what I use as a last step to clean before painting.  It seems a tad oily to me, but it's supposedly made exactly for this purpose; cleaning before painting, and leaving no residue.

Mar 7 - patch 4 epoxied rivet holes for smooth surface, prior to priming.  On 2 of the holes, the epoxy I'd put in a while ago hadn't quite come up flush with the surface, and 2 had pinholes to fill.  Update web site.  0.5 hr + 0.5 hr doc

Mar 8 - prime C702, paint frame until I ran out of paint.  1.0 hr

  Here's the first part of painting the frame.  I take it out in the garage, paint it quickly, use an LP camping heater to warm it until the paint flashes, then I bring it back in the house.  I painted this until I ran out of flat black paint.

Mar 9 - more taping & finish painting frame  2.0 hr

Mar 10 - final frame paint touchup, remove masking, roughen aluminum  1.0 hr

  Here is the frame, fully painted flat black inside & out, with the masking removed.  You can still see the line that marks where the fwd edge of the bubble is.

  Here, I have used 80 grit sandpaper to scuff the skin 3/4" aft of the line, to the edge of the black paint, and about 1" fwd of the line.  This is so the epoxy will grip well.  I also used the same sandpaper to scuff the fwd inside 3/4" of the plexi bubble.  You can still see remnants of the blue line.

Mar 11 - Start epoxying bubble to frame.  Start with outside corners, and frame lying flat.  I am applying the epoxy from the inside, as it is easier to control the epoxy flow when dealing with a concave surface than when dealing with a convex surface.  By tipping the frame & bubble at different angles, I cause different portions of the bubble/frame line to be level.  Then I let the epoxy flow into the level part.  I am using clear poly tubing in my mouth to suck some epoxy up into the tubing, then I put the tubing where I want to apply the epoxy, and blow the epoxy into place.  This worked OK, but the next batch will need to be thinner.  It was some pretty hard sucking and even harder blowing, especially after the stuff stiffened up a bit.   I used 1 heaping plastic soup spoon of microballoons and 1 stroke on the pump.   I think 1/2 spoon will work better for the next batch.   I am using a "flow" epoxy application process, rather than a "pasting" or "putty" application, because I think the flow of the epoxy will form a closer fit, without gaps or air pockets, between the bubble and the frame.  I knew I wanted a liquid flow, rather than a paste, for better contact, and it’s a whole lot easier to control the flow on the concave inside than the convex outside.  I pondered it quite a bit before doing it.    In fact, one of the reasons I got the clay earlier was to make a dam on the inside, but then I decided the dam was better if placed on the outside.  I started by reaching in from the outside, but as I worked toward the center, it got harder to do.    Finally, I tried it by sitting on the inside , and it was super-easy – I didn’t think I’d be able to see the epoxy from in there, but it turned out to be MUCH easier and more visibility and control, so I didn’t get the stuff all over.  I also used black epoxy coloring.  I was afraid it would take a lot of the coloring, or it would end up gray, but after I tried mixing in a small amount of the coloring, the batch of epoxy turned from pure white to jet black.  I'm making it black, following an idea from Len Loudis, so the color doesn't stand out and contrast.    This way, when seen from the inside, the epoxy will match the black paint I used on the portion of the C702 skin that is under the bubble.  Update web site  2.5 hr + 2.0 hr doc

  It's very difficult to photograph stuff so you can see it well, when everything in the picture is clear or a slightly different shade of black.  Here, A is the top edge of the epoxy, covering where the tabs from the WD716 and WD725 overlap under the plexi.  B is the masking tape dam between the bottom edge of the plexi and the C702 skin.  You can see where the epoxy colors the tape as it flows in and fills the dam.  The red line shows the edge of the plexi.  C is the scuffed portion of the C702 skin that was not painted.  C is also where the epoxy has not flowed to yet.  D is the C702 skin where it was painted.  At E, you are looking through the plexi into the epoxy, and at F you are seeing the painted C702 skin through the plexi and the protective sheet.

Mar 12 - Over the course of the day, added 4-5 more epoxy batches in sections.  I started with the frame flat on the table and did the aft corners, then tipped the frame up so more fwd parts of the skin/bubble junction would be level for the epoxy to flow in.  HERE is a link to the user manual for West System epoxy.   4.5 hr

  The red line is the bottom edge of the plexi protective sheet under the plexi.  The white line is the bottom edge of the plexi.  The top edge of the epoxy under the bubble is about halfway between the 2 lines, but not really discernable in this pic.

  Here I am, sucking epoxy up into a tube, so I can then reach under the frame and blow it into place inside the bubble, between the fwd edge of the bubble and the C702 skin.  I highly recommend the use of CLEAR tubing if you choose to do this!

  Here's the last bit of epoxying needed, in the front center.  The red line shows the top of the epoxy, under the plexi, where the C702 skin paint line stops and the scuffing begins.  It's 3/4" from the bottom edge of the plexi, seen here in the middle of the band of masking tape, to the edge of where the skin is painted.

  Here is the canopy, tipped all the way up to get the epoxy level in the last section, in the front center.

Mar 13 - Finished product came out very good.  This came out so good, you could almost just go with it as is.  Lay out & plan for filler to smooth the transition between skin & plexi.   The LT corner is a bit too high.  The edge of the plexi is higher than a straight line between the fwd edge of the skin scuffing and the top of the epoxy under the bubble.  Used a file to grind down the edge of the plexi in the middle of the side curve on the LT side.  1.0 hr

   I just need to make a smooth transition now from the fwd edge of the scuffing on the skin to the top of the epoxy, between B and C.  A is the epoxy that came out under the bubble and was held in place by the masking tape dam.  B is the epoxy through the Plexiglas.  C is the C702 skin, painted flat black, seen through the plexi only.   D is the C702 skin, painted and seen through the layer of protective skin on the inside of the plexi.   It's very difficult to photograph stuff so you can see it well, when everything in the picture is varying degrees of clear or black.

Mar 14 - File edge of LT corner plexi, so it lies flatter, for better transition.  Plan for layout for adding filler.  Update web site.  1.75 hr + 2.0 hr doc

  View from the LT side, over the corner, looking toward the center.  I had to bevel the edge of the plexi through the curve at the LT fwd corner, to enable a smooth, straight transition from the plexi to the skin.  Otherwise, the edge would have been higher than a straight line from the plexi, above the edge, to the skin.

Mar 15 - Lay on first layer of filler.  I did the first part thin, for the RT corner that had no epoxy come thru under the bubble  I had to tip the canopy up at an angle so the corner was on top.   As mentioned earlier, flow control is difficult on a convex curve.  The epoxy kept wanting to flow to the edges. I used some clear shipping tape at each end to hold the flow in place.  Then, I added plenty of microballoons to the mixture, until it was as thick as taffy.    I laid that down as a bead along the top of the epoxy that had flowed under the bubble, to build it up.  For some reason, the thick stuff hardened MUCH quicker than the thin stuff.  If anything, I'd have thought it would be the other way around.  Updated web site.  1.5 hr + 1.0 hr doc

  Here, at the arrow at the top, I am adding a thin epoxy mix to the RT fwd corner of the bubble, where it was so tight to the skin that the epoxy didn't flow under it.  As mentioned earlier in my reasoning, it's a lot more difficult to control flow on something convex, but this was only a distance of a few inches.  The canopy is tipped at a compound angle so the place needing epoxy is at the top.  Even then, I had to add tape at the 2 lower ends of the new white epoxy, to keep it all from running away.  The red line in the middle shows the approximate epoxy line.  The rest of what appears to be solid black is just the top of the painted C702 skin, seen through the inner layer of bubble protective plastic layer.

  Then I took the rest of the one-pump batch I'd made for the top part that hadn't gotten epoxy flow under the bubble, and added plenty of microballoons until I had the consistency of taffy.  Then I applied that epoxy as a first layer fwd of the black epoxy, as a first step in blending the bubble into the C702 skin.

Mar 16 - Oddly enough, the thin epoxy I did last night is STILL a bit tacky feeling.   Used Karla's hair dryer on it awhile.  Didn't seem to make much difference.  Sanded the first layer of microballoon filler I put on.  Also made the first attempt to lay down the electrical tape to define the borders of the epoxy application.  0.5 hr

Mar 17 - After looking over how Dan Checkoway did his bubble fiberglass/blending work, I decided that I should have put some fiberglass cloth in there, instead of building it all up with microballoon/epoxy mix.  So, I put a cutoff wheel in the drill and used that to grind the convex top off the bead of white microballoon mix I'd put on.  I didn't try to take it ALL off, but I ground it down so it's flat and in line with plane of the bubble, rather than convex.  Then I laid 3 layers of glass cloth over that.  Doing the fiberglassing went well.  I also put a heater under the frame awhile, to try to get that RT corner where I put the thin microballoon mix, to lose its stickiness. 1.75 hr

  Here is the canopy, after I finished grinding down the first layer of epoxy/microballoon filler I'd laid down.  I also have the red electrical tape defining the approximate top of the epoxy filler line.  I spent a lot of time agonizing over how to put down the tape so it's perfect.  I finally just gave up & put it on.  I guess it's OK, but I wish I had a more definitive way of deciding exactly where to put it.

  This is a close-up of the microballoon filler I ground down.  The blue line represents the fill line I plan to use; a straight line from skin to bubble.  I think it'll be easier to do, and I think it will let the airflow change directions more gradually than coming in flat the base of the bubble, then suddenly curving up.  This pic was taken when I was partway done grinding down the filler in the middle.  It had been convex, to fill up the depth of the gap in the middle, but then I decided to lay some glass cloth in there, for more strength.  After taking this pic, I ground more on the fwd edge of the white filler (LT in the pic) so it blended as well with the skin on the LT as it is with the bubble on the RT.  Using the cutoff wheel, very carefully, worked quickly and quite well.  Then, I was ready to glass it.

  This is after laying down 3 layers, about an inch wide, over the microballoon filler mix.  I could have done more work, but I used West Systems FAST hardener, so this was all I had time for before it started stiffening up.

  This is a close-up of the first 3 layers of fiberglass.  In the background, you can see how I ground the microballoon filler to be a smooth straight line between the bubble and the skin, for a better surface to lay the fiberglass cloth onto.  I'll build up the middle, where it needs the most filler, with fiberglass cloth, then I'll finish it with microballoon mix.  I didn't let the width of the cloth get any closer to the to/bottom edges, because then it would have made the subsequent feathering more difficult.  The bottom of the red tape is the top of the black epoxy I had flowed into place.  The black you see above the red tape is the painted skin, seen through no layers of plastic protective layer.  Above that, you're looking through just the inside layer of protective plastic, and above that you're seeing through both the inside and outside layers of protective plastic.

Mar 18 - That RT corner, where I put the thin microballoon mix, is still slightly tacky.  It seems hard under the surface, but the surface is a bit sticky.  I know I mixed it a LONG time when I made it, and the same mixture later hardened OK when I added the microballoons.  I decided the surface must have reacted with the adhesive on that clear shipping tape I used to make a dam.  I used my trusty cutoff wheel in the drill and ground down the top of that portion of the filler.   It seemed hard & non-sticky after that.  MORAL = don't use clear shipping tape on the epoxy.  Then I laid down 4 more layers of cloth, using the West Systems SLOW hardener, so I'd have more time to work with it.  I also laid down 3 additional short layers on each corner, where it needed more building up.   That should be all the fiberglass cloth I need.  I will fill the rest and feather the top & bottom edges using the microballoon epoxy filler.  Update web site   1.5 hr + 2.0 hr doc

Mar 19 - grind down high spots on resin/fiberglass cloth.  I decided to pull off the red electrical tape and reposition it better.  Even though the tape looked symmetrical when looking at the bubble, I realized it was not an equal distance from the tape to the rivets.  This would show up as unsymmetrical when I finish the fill work and paint it.  I taped a Sharpie to a divider and used that to mark symmetrical lines along the bubble that were equidistant from each rivet along the rivet line, working from the center out.  I marked the distance from the rivets and put the tape down a couple times, but I was not satisfied with the work, so I ended up pulling the tape off completely, and removing all the marks, to start over from scratch.  3.0 hr

Mar 20 - Did a final layout of the tape lines and laid the tape down again.  It seemed pretty good, so I decided to go with it.  I sanded all the exposed plexi and skin in preparation for the first layer of microballoon epoxy.   2.0 hr + 0.5 hr doc

  Laying out the tape line again, so it's perfectly symmetrical with regard to the rivets & frame/skin.  I just taped a Sharpie to my dividers, and made sure the bottom edge of the tape was the same distance from each rivet on each side, equidistant from the center.

Mar 21 - mixed up the microballoon filler.  I used 1 heaping plastic soup spoon plus 2 level spoons, to one pump from the West Systems epoxy.  It was TOO THICK.  It worked OK, but barely.  It got too stiff too quickly.  It was OK as a first coat, but it was too thick and hard to lay down.  Later on, laid down another coat, using 1 heaping spoonful and 1 level spoonful.  That worked out pretty good.  2.0 hr

  First coat laid down.

  Second layer goes down.  Getting there slowly.  In the upper LT, you can see the shape I'm heading for; more of a gradual straight line than a sudden curve.

Mar 22 - laid down a couple more coat over the course of the day & night.  This stuff doesn't really lay down like Bondo, or maybe it's because I'm being careful to not get it on the bubble or skin anywhere I don't want it permanently.  It seems to take a lot of thin, spotty layers to get it to properly fill in.  It tends to ride along the rubber application paddle, rather than flowing down into the low spots.  I'm using a Bondo squeegee that I cut to the exact width of the final distance from the bottom of the red tape to the skin (1.75").  The final few coats will probably be thinner, so they flow into the low spots better, when the layers are of a low enough depth that they'll be less likely to run.  2.0 hr + 1.0 hr doc

  I cut this body filler spreader to the length I wanted from the bottom of the red tape to the skin.  This is 1.75", and gives me about 1" up the bubble and 1" fwd on the skin.  I just move the squeegee along, keeping the upper corner against the red tape, and it should come out very smooth and even when I am done.

Mar 23 - did another layer.  1.5 hr + 0.5 hr doc

  A few more layers later, and it's starting to get there.  It still needs several more.  In the background, over the center of the canopy frame (this is taken from the RT edge), you can see how the line blends from the skin into the bubble shape.

  One problem I am increasingly having is that a one-pump batch is way too much, especially as I get closer to the finish product.  Here, at least 3/4 of the batch is left over, after I've done all I can for now.  I don't trust trying to judge doing "half-a-pump".  Today, I ordered some more epoxy and hardener from Soller.  I asked Jon Soller about the problem.  He said I can mix up smaller batches by using a 1:5 ratio of hardener to resin, so I'll be doing that in the future.

Mar 25 - get some Evercoat Rage Gold body filler and lay down a thin layer of it.  1.0 hr

  I happened to catch a mention on the RV7 list about this Rage Gold body filler.  Everyone raved about how good it is, so I went out & got some locally, along with a palette and an assortment of spreaders.  It's a sick green color, and the hardener is blue, so it mixes up to a putrid "bug-guts green" color.

  Here's the first layer of the Rage Gold filler.  I really didn't think it went down any smoother than the microballoon filler I was using.  Look at how rough it is just under the red tape, near the center of the pic.  It also hardens very fast, which can be good or bad.  I tried to minimize the amount of hardener I used, but I still only got about 5-10 minutes out of it.  I only got less than halfway across the bubble/skin joint before it got too hard to use.  Because it hardens so fast, it is also harder to clean up than the epoxy.  With the epoxy, I can work in a more leisurely fashion and when I am done, I just wipe things off with a paper towel.  Of course, then I have to wait several hours for it to harden, especially when I am using the slow hardener.  I also like the fact that I can control the viscosity of the microballoon mix, depending on what I am doing with that particular batch.  I make it thinner as I get closer to the finish product.  I guess I will try more of the Rage Gold; after all, I now own a *&^%$#@ gallon of it. 

Mar 26 - Went back to using epoxy/microballoons mix, as I like it better than the body filler.  For my current schedule, where I can only get in an hour or so once or twice a day, the longer curing time of the epoxy (compared to the Rage Gold) is not a factor.  I stole a 1/4 teaspoon measuring spoon from the kitchen, and I now use that to mix up the epoxy.  One 1/4 tsp of hardener mixes with 5 1/4 tsp of epoxy and gives me a good quantity, without wasting so much.  Update web site  0.5 hr + 1.0 hr doc

Mar 27 - In the AM, I decided that, if I feather the epoxy into the bubble under the red tape, then when the red tape is removed, it will be very difficult to determine where the paint line should be when the canopy exterior is painted.   So, I decided to fill fully to the tape line and leave an edge as thick as the tape.  I laid a piece of black tape down over the red tape, about 1/16" higher, so I can fill right to the red tape.  This way, there will be a distinct line there the thickness of the tape, so I will know where to tape for masking for paint.  Then I laid down another layer of microballoon mix, starting to get it right up to the red tape.  In the PM, put on another layer.  2.0 hr

Mar 28 - Put on another coat of microballoon mix.  I expect to go back to the Rage Gold for the final touchups.  1.0 hr

Mar 30 - Sanded in prep for another layer.  0.5 hr

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