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  #461  
Old 01-28-2020, 05:40 AM
RV3Kev RV3Kev is offline
 
Join Date: Sep 2017
Location: Traralgon Australia
Posts: 31
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Dear Paul

Whats the strategy with the foam when forming the canopy skirts? I would have assumed you have would have to have the canopy frame located on the fuselage to get the right shape
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  #462  
Old 01-28-2020, 09:21 AM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,091
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I'm not using the aluminum canopy frame. The plan is to make the fairing, add the flanges for the canopy, and then reinforce the fairing to make it an integral frame.

Dave
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  #463  
Old 02-07-2020, 03:20 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,091
Default Mud on Foam

After some more work shaping the foam, I was ready to seal it. The main issue was that Iíd shaped it a bit too far on the sides in the middle, losing some of the compound curvature that you ca see in the top center. I needed to build that up and fill in some gaps that remained in the foam mold.

Drywall compound is the answer. It allows a build-up, the consistency is the same across multiple layers and that avoids sanding discontinuities. Also, itís cheap and I didnít have to mix it. Normally, I would not permit this anywhere on the plane, but since this is a mold, not a flight part, itís okay here.

This is after Iíd just started on the right side. Previously, Iíd verified that the drywall compound will stick to the foam. I'm just using a yellow plastic epoxy squeegee for this instead of my drywall tools. They can't handle compound curves.



And hereís the other side ready to dry.



The instructions say to apply it in relatively thin coats to avoid cracking as it dries.

For actual drywall, Iíd try very hard to smooth the surface at this stage and avoid sanding. In fact, thatís a difference between a drywall pro and a beginner. The pro doesnít need sandpaper, or at least not much. Here, with the compound curved surface, thatís difficult, and also I donít need a finished paint-ready surface since itíll be covered with plastic.

Dave
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  #464  
Old 02-13-2020, 09:26 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,091
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Waiting for drywall compound, aka "mud," to dry means that I needed to find something else to do for a while. The F-319 (or it might be F-317 or F-318, it's called all of those. But on drawing 22, it's F-319) aft deck was cut out a while ago but not drilled for installation. It's intended to be riveted to the longerons and the F-309 bulkhead. On my plane, it'll be attached with screws so that I can remove it for access to the area.

I measured where the holes should be and marked some to avoid drilling until later, just in case the horizontal stabilizer blocks a portion. Then since the .040 aft deck was opaque and I couldn't verify the longerons under it, I overlaid a bit of that .030 Lexan that I'm using as patterns and transferred the hole locates to that. Placing it over the longerons, it was obvious that I needed to shift the hole locations just a bit outboard for better edge distance. No problem, since I could see exactly where to put them.

The .030 Lexan is sourced at McMaster. It comes with a matt plastic protective layer, much like the blue vinyl we enjoy so much, except that it's translucent. It easily holds the Sharpie marks and the sheet is stiff enough that It makes superb patterns.

Once the Lexan template was overlaid on the aft deck, I used my handy Verits optical hole punch to punch through the Lexan into the aft deck. The next step was to drill the holes to #50. Why #50? Because that's small enough that if necessary, I can walk the hole to a slightly better location, and also because a Sharpie just fits and I was able to mark the longerons with the hole locations.

Removing the aft deck, I checked the hole locations on the longerons and verified that they were acceptable. Then I pilot-drilled through both the aft deck and the longerons with a #4The large access holes still need to be made.



The large access holes still need to be made.

You might notice a small part at the forward left of the deck at the bulkhead. That's an oopsie. I'd drilled a hole for the OAT sensor in the wrong location and that conflicted with where the screw hole needed to be on the aft deck. I made this small part to get to a better spot. After the photo was taken, I trimmed the part to make it smaller. You can see the new OAT hole above it on the bulkhead.

The mud is coming along nicely. It's just slow, is all, in case you were wondering.

Dave
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  #465  
Old 02-14-2020, 09:34 AM
AndyRV7's Avatar
AndyRV7 AndyRV7 is offline
 
Join Date: Sep 2007
Location: Hudson County, NJ
Posts: 1,088
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Looking good. Thanks for the big pics!
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  #466  
Old 02-14-2020, 08:12 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,091
Default Trial Fit, Nothing More

The aft deck needs three holes cut in it for access or lightening or something. The location of those depends on where the horizontal stabilizer goes. With the aft deck clecoed to the longerons, I pulled the stabilizer down from the rafters and clamped it into position. Except for fore and aft, I made no effort to align it. I even left the protective bubble-wrap on.

The forward flange of the inboard nose ribs on both sides are flush with the skin. These interfered with the aft top skin, the turtledeck. The interference was small, maybe .090 spanwise and perhaps 1/4 inch long, and just on the bottom of the stabilizer. I trimmed these with a Dremel and a sanding drum, finishing with a small fine file.

Later, talking with my mentor, I learned that this is common on RV-4s and Rockets, too.

After clamping the stabilizer in place I measured where the various mounting parts will have to go and took this photo.



While I was tempted to bring the vertical stabilizer down from the rafters and clamp it on, too, I refrained. We all know where that would lead: lining these parts up and hanging the elevators and rudder. One of these days, but not today. Instead, I put the horizontal stabilizer back up in the rafters for now.

Dave
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  #467  
Old Today, 08:39 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,091
Default Aft Deck & Fairing Compound Curve

The fairing mold is nearly there. I'm currently working on eliminating waves in the surface from the sanding. Even though I'm using longboard sanding, I'm still getting them. Fill and sand, and they're improving.

The photo shows the compound curve in the surface that I'd mentioned.



The aft deck is getting closer, too. The access holes are in it and the left forward flange repair is riveted on.



Dave
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