Chapter 23 – More armpit ramps

Shortly after I got into the shop this morning Marco called to discuss some tweaks he was making to his Garmin GNS-480 GPS antenna install.  As we were talking I walked around to the back of my plane to find a very curious lizard inspecting my build progress.  I wasn’t sure if he was happy with the build or not since all did was keep tilting his head from one side to the other… ha!

I’m having to change up my schedule to allow for the minimum 24-hour cure cycles with my new Pro-Set epoxy.  As I’m sure most of you are aware, I’m a big fan and normally use MGS with fast hardener.  I know the final Tg isn’t as stellar as slow hardener, but it’s still well within the really good range and my productivity is exponentially higher using fast hardener.

So as the aft right 3-ply CF cowling flange layup continued to cure, I decided to knock out adding some G10 “hardpoint” strips to the top aft of each of the armpit intake air- directing cooling ramps.  Since I only used 3 plies of CF for each ramp, they’re fairly thin.  So to reinforce them and add some thickness I’m adding a strip of 1/32″ (0.030″) G10 to each ramp to allow me to attach —with rivets— the top aluminum side of each ramp.

I cut each strip just over 0.4″ wide and also a little short from each end to allow a good grip onto the CF with the overlaying single ply of BID I’m using to secure this G10 strips in place.  BTW, this ply of BID will also prevent any possible funky reactions between the CF and the riveted-on aluminum top segments of the ramps.

After cutting the G10 strips, I then sanded them and cleaned them up with Acetone.

I used just a dab of flox for very wet flox when I attached the G10 strips onto the face of the CF ramps.  I then used fairly dry micro around the edge for a transition and then laid up a ply of BID over the top of each G10 strip to secure them to their respective CF ramps.

After well over an hour of cure time, I then transferred all the ramps onto a work board and weighed down the added G10 strips and their securing peel plied layups with metal sheets to ensure that they cure as flat and straight as possible.

By this point my 3-ply CF flange layup on the right side of the top/bottom cowl interface had cured enough where I could remove the peel ply on the inside.

It took a good half hour of measuring and working out numbers to finalize my spacing for the 4 CAMLOCs that I’ll be installing along the aft cowling interface to secure the top and bottom cowlings together.

Here we have the aft 2 CAMLOC positions drilled with Clecos installed.

Also note that I pulled the peel ply on the narrow outboard strip of the 3-ply CF layup as well.  Again, this narrow strip will get filled in with more CF to build/extend the “skin” of the top cowling to meet the bottom cowling’s outboard edge.

It may not seem like a lot of work got accomplished today, but let me tell ya: adding those G10 strips to the aft top of each air inlet ramp took well over 3 hours total.  Tomorrow I plan on jumping full bore back onto the top/bottom cowling interface layups.

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