Chapter 18 – Canopy (Part 2) – 84 Hrs

Canopy Forward PieceMarked the canopy to cut off the forward section.  Attempted to use Wayne Hicks method, but with all the bumps and joggles with the FHC, it didn’t work as well for me.  With needing to open the gap to 1/8″, I was able to even things out with the long board sander.  I also had to fix a few saw cuts, but otherwise it turned out pretty well overall.  Cut some 1/8″ pieces of foam to make the drip rail and fastened to the canopy with duck tape.  Applied 2x BID, 2″ wide for the drip rain and peel ply’d.

Front Piece Drip EdgeGlassed the foam where the saw cuts were using 2x BID and flox corners, and extending on the drip rail.  Floxed the forward piece to the canopy and used peel ply on flox in prep for glassing.

Front Piece Glassed PermanentlyGlassed the under side of the forward piece to F28 with 2x BID and peel ply’d.  After cure, glassed the top of the forward piece with 3x UND and peel ply’d.  Glassed with 6x BID for the canopy lip over the front piece per plans.

Hinge AlignmentNext was mounting the hinges.  Checked for fit, and noticed my canopy hard points are a bit  closer together than I thought.  The FHC plans say they need to be that far apart for the radio stack to fit, but it looks plenty wide for that.  Given that I am going with a glass panel, I’m not too worried about it right now.  These plans were made for the Cozy 3 which is a bit narrower, so understandable that the hinges are not the same dimension
Canopy Hinges in Actionto the fuselage sides.  With everything matching and clamped in place, I measured between the hinges to verify the hinges will open parallel to each other, and laid a level across the longeron and checked the canopy frame angles were parallel to the level when pressed against it.  Once everything was verified, we verified with the canopy on one last time, removed it again, and drilled the mounting holes through F28.  Used a 3/16″ twist drill bit, as I couldn’t find a #8 that was long enough to clear the forward part.  Wasn’t able to get a 90 degree hole in the top holes toward the inside, as the forward part again is in the way, so the bolt is at a bit of an angle.  After bolting in place, put the canopy back on and checked fit one last time.  Unbolted the hinges from F28 added flox to the angles that will connect to the canopy frame, and bolted back to F28, making sure not to touch the floxed portion to the canopy frame yet.  Mixed up some 5 min epoxy with flox, and after pushing the floxed hinge onto the hardpoint on the canopy rame, I put dabs of 5-min on the side with the flox, but there is not much room to work there, not visible, and limited time for the 5-min to set up.

Hinge to Canopy AttachmentIn trying to get the canopy off with the hinges floxed in place, it was not clearing the forward part and the hinges ended up coming off the pads.  Had to cut some clearance slots for the hinges to fit into to solve that issue.  Luckily the hinge bases left a perfect impression into the flox so I could still align it perfectly to drill the holes.  Drilled the 3/16″ holes on the pad side and up through the top.  Followed with a 1/2″ spade bit from the top for quick material removal.  Once close, finished up with a counterbore bit for a flat surface.  Bolted in place and test fit to find that I need to sand down the overhang lip over the forward part.  Also needed to increase the cutouts for clearance for the hinges.

Mold Taken for Instrument Panel CoverNeed to create the instrument cover, but with the thick pads for the canopy hinges, it won’t work per plans.  I ended up using the canopy as a mold and covered it with 2 layers of duct tape for mold release in prep for glassing.



Instrument Panel Cover FormingGlassed the instrument cover with 2x BID by using some scraps of glass.  Covered with peel ply.  Once cured, I prepped the instrument cover to glass in the curved piece behind the breakers at the top of the instrument panel.  Carved some urethane foam to fit in the opening that was left from using the canopy frame as a mold.  Hot glued the foam to the IP and added the 2″ in front of the IP for a glare shield.

Instrument Panel CoverGlassed 3 ply on the breaker cover portion of the IP cover.  Put peel ply down first, then 3x BID, and then peel ply again.  Was sure to put the first layer of peel ply under the OP so it didn’t interfere with adhering the two pieces together as one.

Now that the wedding is done, it’s time to get working on the Cozy again.  Figured out how I will lift the canopy while not having the latching system be in the way.  Ultimately I settled on the plans lay down gas cylinders.  My main issue with this was that with my latching system, I could not install the “Thrust Bolt” shown on page 20, section EE of the FHC plans.  This is because my latching system is mounted along the face of the longeron, instead of under Additional Hard Point Prepit, like the standard plans.  This is not in the FHC plans, but is a design by Ed Richards.  To solve this, I decided to move the thrust bolt further forward, and create something to attach to the canopy to take the loads of the gas springs.  This will take the place of C8A in the FHC pans, and this will be adjustable for future maintenance.  With this figured out, I was able to determine where my hard points would need to be installed.  Once figured out, I removed the Additional Hard Pointsglass and foam for the hard points, then proceeded to start grinding away the glass around the hard points in layers to prepare for scarf joints.  Once ready, I taped around the hard points and completed the glass/flox layups for the hard points.  After cure, I created paper templates of the layers needed for the scarf joints and cut all the glass.  Then layed up all the layers with 1 extra BID covering, and covered with peel ply.

Finished Hard Point PatchAfter cure, I started to attach the gas shocks.  Drilled my holes in hard points to attach the ball studs and counter bored the holes so I could attach the nuts.  I then moved to the attach points on the longerons.  I cut out two 1.1″ x 2.5″ pieces of 1/4″ 2024 T3 aluminum and drilled holes per FHC plans.  Then used the holes in the aluminum as a drill guide, drilling the 3/16″ holes through the longerons, placing AN3 bolts in each hole after drilling.  With the bolts in place, I
Canopy Shock Ball Studused the 5/16″ hole in the aluminum as a guide to counterbore the longeron far enough for the ball stud to clear.  Since I needed it to fit in the hole with the nut fastened, I opened th hole up to 5/8″.  Counterbored the holes running through the longerons and was ready to assemble.  I had to remove 3″ of the instrument panel inboard from the longerons for the gas shocks to lay down properly.  Hooked up the shocks to test, but found that the shocks are not strong enough to hold the canopy open Gas Shock Mountingand do not open far enough to get in easily.  For replacement shocks, I was able to measure from ball stud to ball stud in both the closed and fully open positions to get the compressed and extended lengths, but I didn’t have access to a spring scale strong enough to measure the force needed.  Then I realized that I had known values of the 90 lbs  each for the shocks that I had, so I just needed to attach some twine around the ball studs and measure the amount of force needed to lift the canopy.  52 lbs additional on the fish scale to lift the canopy.  I settled on the Strong Arm 6922 gas shocks, with 14″ extend length, 8.75″ compressed length, 123 lbs, 10mm sockets for both sides.

20151013_223124.jpgI then started with the latching mechanism.  Measured for the holes to drill through the longerons.  Once measured, I drilled the 5 holes on each side.  Four for the latches and one for the outside handle.  Counter bored the 4 latch holes on the outside and fit the attaching hardware.  Drilled through the shoulder brace for the draw rods to pass through.  Attach all the latching hardware together to test fit.  Once fitting correctly, floxed the permanent pieces to the fuselage.

Once the flox cured, I assembled the latch 20151013_223132.jpgmechanisms, reattached the canopy, and realized that the widening of the canopy made it so the hard points are hidden over the longerons and I canopy attach the canopy hardware per the plans.  After far too much trial and error, I had Kim make some 90 degree 2xBID over a 2×4.  After cure, cut them into strips (1-2″) and 5 min epoxied to the side of the canopy, after lining them up correctly to the latches.  Added 2xBID on the Canopy Latch Hard Point 2 Canopy Latch Hard Point 1





Canopy Latch Hard Point 3bottoms, and realized that I had to auger out a  cavity on the inside of the front latches to get a bolt into it.  After that, I could add 2x BID on the inside of each as well.  Lined up the latch hardware and bondo’d in place long enough to match drill the holes through the hard points.  Removed the hardware, opened up the holes for an AN3 bolt, and tapped the holes on the hardware.  Had to add additional layers to the bottom of the hardpoints to get the spacing correct and get the latches to work smooth.

Instrument CoverRemoved the canopy to finish up on the IP cover.  Cut the sides off to build a cavity for the gas shocks.  Built up the cavity and glassed 2xBID in the cavity.  Finished with another ply covering the rest of the IP cover for a total of 3 BID.





About Tarmac Grazer

I have recently purchased Cozy MK IV Plans #1627, and will be using this blog to log my build progress.
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