Chapter 23/25 – Cowl glass required

Today was about knocking out some glasswork for upcoming tasks as well as remounting the lower cowling and assessing clearances with the engine now back in its original position.

Starting off, the outboard edges of my strakes tend to dip down right in the last 0.5″ inch around the perimeter of the strake edge.  This dip of course causes there to be a more pronounced uneven skin height level between the wing and the strake.

Instead of just slathering on a bunch of micro, flocro or flox, I wanted to both stiffen this edge up a bit while giving it some increased height to better match the wing.  On the end of both strakes I determined different thicknesses of BID that I was going to add, ranging from 1 to 5 plies.  3 plies was the most common addition, while I only needed 5 plies in one spot on each side, both about 3/4″ in length.

The width of the added BID started out as 0.4″… clearly it varied a slight bit as I manipulated the layup around the leading edge.  After prepregging the BID and getting it laid up, I then peel plied the layups.

A few hours later I pulled the peel ply and cleaned up the layups.  I may add another ply or two to the still considerably depressed spots, but the majority of the areas I’m calling good and feel comfortable with still a decent application of micro on the edge now.

Another glassing task that I have on my list that needed to be done before I consider this bird operational is a reinforcement layup on the pilot right armrest.
[I have just under 20 layup jobs that I’ve identified that need to be done (each task may require multiple layups).  About 75% of those must be done before the airplane goes airborne, others are mods such as baggage pods, wing LE landing lights, HUD mount bracket, etc.]

The plans call for 2 plies of BID, but I only used one.  Now I’m reinforcing the center area where I will push down when extracting my less-than-Twiggy self and getting into this bird.

Plus it was a fairly quick kill and I was trying to get out the door to meet Jess for a late dinner.  Not surprisingly, all the glass & CF I used were scrap pieces.

Here’s both sides of my Lantor Soric test piece that I laid up 1 ply of BID on each side.  One side was peel plied, the other not.  Yes, there’s air gaps around the perimeter where having a micro (or flox) transition would be good of course.

With a ply of BID on each side the thickness came out to almost 1/8″.  Also, as you can see on my well used scale (it means I’m building a lot! … ha) my ~2″ x 2″ test piece is a whopping 8 grams.

If you’re wondering why I’m interested in this Lantor Soric stuff, it’s because it will be the material that I most likely construct my wing/aileron fences out of… so far so good!

After returning home from dinner, I tucked away all the dangly stuff on the engine to allow me to mount the bottom cowling to assess clearances.

Yes, the gap between the spinner flow guide and the lower cowling is much tighter now, at just over 0.45″ … but I can manage that with no serious effort.  The big issue is the inboard left exhaust pipe, which the bottom of the 90° bend is now touching the cowling.  Moreover, my carbon fiber induction tube is just a hair away from the cowling as well… although not touching!

If you look closely you can see black Sharpie marks all over the bottom cowling.  I spent a good 45 minutes assessing my next steps, and yes… I will be recontouring major portions of the aft, mid to upper areas of the bottom cowling.  In addition, I will be extending the tail end transition of the RAM air scoop all the way to about 10″ in front of the boat tail “rudder” fin.  This is the only way I can see to add in some clearance to the air induction tube on the bottom of the cowling without a total rebuild.

More to follow of course, and I plan on getting started soon.  But we’re having another major heat spell… I went to have a glass of red and ponder my bottom cowling fix actions on the front porch at 11pm tonight and it was over 90°. . . clearly just too darn hot.  My point is that I will not be doing a lot of sanding on the bottom cowling during super hot days, so it may be a few days before I get a somewhat cooler day to knock that out.

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