Chapter 21 – Strakes (Up to T-Hats) – 94 Hours

Strake BulkheadsI had already joined and glassed two sheets of foam per the Cozy Girrl’s method.  After cure, traced all the bulkheads onto the sheet and cutout all the bulkheads.




R33 & R57 PlacingUsed the Bernie Siu’s dremmel trick to auger out some foam from the half circle openings, and filled with flox.  After cure, I aligned the R33 and R57 bulkheads and floxed to the spar.  Used the floss technique to align the 17.4 W.L. stretched between the fuselage and the outboard rib I added (not in the plans).


R33 & R57 Glassing 2After the R33 and R57 bulkheads cured in place, I fitted the connecting bulkheads, sanding the connecting edges to the correct angle for a custom fit.  Test fitted everything using drywall screws to hold together.  Floxed all but the leading edge bulkheads together and 2 BID taped.  Finished with peel ply.


R33 & R57 Glassing 3Taped the leading edge bulkheads in place.  After cure, figured out where to flox the extended strakes to the fuselage.  With sanding down the front edge of the the extended strake bulkhead as such an angle, the front of the bulkhead is at FS38.3 and the rear is at FS40.0 where it attaches to the fuselage.R33 & R57 Glassing 4






Strake Top Skins Fitting 4Cut out the skins to basic size and fine tuned the top left skins to a good fit.  Had to sand down the tops of the bulkheads a bit to get a flat fit and a nice transition to the spar.  Hot glued some foam pieces for the inboard skin to rest on, and used a straight edge to figure the position.  1xBID on bottom side of both the inboard and outboard top skins.  When ready to bend along the R33 and R57 bulkheads, I used the Andrew Annunson approach.  I didn’t cut my slits parallel.  Especially since I am doing the Cozy Girrl strakes, with the Ed Richards Latch, I need to have clearance for my latch handle.  The far inboard curvature will be much more gradual and take a longer distance to make the same curve.  With the fuselage level, I used a level across R33 to the fuselage on the foam pieces that are hot glued.  I did this where the curve starts flattening out.  When level, I mark both locations.  Then I measure the distance along the bulkhead/fuselage to get that height.  (Fuselage=30, R33=10.2)  10.2/30=.34 Inboard Top Skin.  So the slits would be 1″ at the fuselage, but only .34″ at R33.  I repeated this process for the outboard top skins as well, getting 3.9″/5.4″=.72″ or .5″ at R33 and .35″ at R57 for narrower slits.  Using this method made very nice bends with no flat spot mentioned so often in the archives between R33 and R57.  The inboard slit, I covered in masking tape before I made my cuts, but the masking tape was starting to come off before I could fit with curvature.  I managed, and filled all the cracks with micro, removed the tape, and let cure in the correct position toStrake Top Skins combining keep it’s shape after cure.  The outboard section I tried adding the tape after the cuts and follow the cuts with a knife and micro right away.  That didn’t work well and I ended up scrapping the tape all together and just microd the foam and cracks figuring I could just sand really well before skinning the top.  After the micro cured, I was able to micro the inboard and outboard top skin on the left side together and glass together permanently with a 2″ BID and Peel Ply.

R33 & R57 Glassing 6I have been repeating the top skin process for the right top skins as well.  Have cut out the top skins and glassed the bottom of the inboard skin already.  Today I completed the slits on the inboard skin after applying masking tape.  (Be sure to run the masking tape in the same directions as the cuts to keep from removing every 2″ along each slit after the cuts are made!)  Applied wet micro into the slots, clamped everything into place, and removed the masking tape for cure.

Glassed the bottom side of the Right Outboard Top Skin with 1 BID and peel plied.  Measured and cut the slits in the right outboard top skin after covering with masking tape.

Placed on bulkheads and micro’d into the clits and used drywall screws to hold onto the bulkheads.  Removed the masking tape and let cure.

Left Top SkinPrep sanded the bulkheads and fuselage side for the T-Hats.  Epoxy’d peel ply to the top skin first where the bulkheads will touch.  Placed in place and weighted down.  When ready, placed flox bead in each of the corners of the fuel bays.  Laid up a section of BID (1 ply) and cut into 2″ strips and glassed into the corners.  After glassing, covered with peel ply.  After cure, trimmed to 1″ wide (not shown)


Left T-Hats


About Tarmac Grazer

I have recently purchased Cozy MK IV Plans #1627, and will be using this blog to log my build progress.
Image | This entry was posted in 21. Strakes, Fuel, & Baggage, In Progress:. Bookmark the permalink.

3 Responses to Chapter 21 – Strakes (Up to T-Hats) – 94 Hours

  1. I really like the deail of your fairing the skin out along the CZ strake. Your photos are helping me learn how to do the strakes on my own inherited kit. Thanks for posting.

    • Glad it is of help! There have been so many other sites that helped me, some of which are no longer available, so I’m glad I can return the favor!

      • Steve Taylor says:

        What are you doing for the canopy ? The FHC ? or the original. I’m using Charles’ FHC, using Audi trunk hinges – they’re the first new parts I’ve bought !

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s