SR-71A Blackbird (Testors) Build #19 – Engine Nacelles Get Some Attention

One of the areas that I thought would give me problems were the replacement resin engine inlets.

Each assembly is comprised of four parts. Fitting them requires that the leading edges of the engine openings be cut back and that the insides of the engine nacelles be sanded/filed away so that they would fit inside the openings. I was pleasantly surprised at how easy that part of the build went:

The round openings in the center of the inlets are where the shock cones attach. Here’s one dry-fit:

While the superglue was curing, I reworked most of the PE grills for a better fit. In the process, a friend of mine informed me of an acrylic putty that he suggested might work well for fine filling jobs:

This product is intended for the autobody trade. It certainly works well for certain applications in modeling!

The green putty works well for filling medium to small voids and depressions, but it doesn’t “feather” out well. When the coat of putty is sanded very thin, it tends to break off at the thinnest sections. I needed something very fine that would adhere strongly to styrene and this 3M stuff does that well:

So now I have three grades of putty, very fine (3M acrylic putty), medium but non-structural (the Squadron Green I’ve been using), and strong and structural (Aves Aepoxy Sculpt):

So, now that I have the resin engine intakes in place, it’s time to fit them. As is evident, the plastic doesn’t quite match the resin:

To start to fix that, I filed and sanded down the areas that are too high. Once done, I used the epoxy putty to bridge the gaps and to fill in sections of plastic that were below the edges of the resin (and it does double duty by being adhesive):

After the first application of epoxy putty and working it down, there were a few places that needed another application of the stuff:

Once the putty had cured and been filed/sanded, there were several places where I needed a fine putty that would feather well…which I just happened to have, now:

Once the acrylic putty was sanded smooth, all surfaces met perfectly:


Then I replaced the pitot tube/yaw sensor with an AMAZING piece. This part is so fine that it looks more like a needle, an actual needle, than it does a model part. It’s comprised of three parts, all of which fit within each other to produce an incredibly detailed part. Once assembled, I cut off the kit part, drilled a socket into the mount, and got the drooped angle of the pitot/probe where it belongs:

With the intakes of the engines taken care of, I turned my attention to the engine outlets. My initial thought was to use the PE afterburner (AB) vanes:

I like the level of detail and the scale dimensions. Unfortunately, the vanes attach to the kit part (shown above between the copper of the vanes and the tan of the resin). What’s unfortunate about that is that there is a curved interior detail that’s missing from the kit parts but present in the resin parts. Yes…I could modify the kit part accordingly, but the technical phrase for this job would be, “a bitch.” Had enough of “bitch” jobs, thanks. Yes, the resin vanes are also going to take some work to approximate what I’m after and the ends of them will be thicker than I’d like, but it’s still less work than filling in the kit parts and then getting that filled section’s profile correct inside a cylinder.

If you look closely at the vane sections below, you’ll note they’re slightly oval. Hot water and fingertip pressure will fix that (in addition to cutting away the excess resin):

Once free and reshaped, the edges of the vanes needed to be sharpened up. To support a fairly thin resin part (the vanes), the vanes were attached to their mount (compare the part on the left, which has been reworked, to the one on the right, which has not):

Then the notches that appear between the vanes had to be cut out (done vanes on the left, unstarted on the right):

And of course, that was done again on the part on the right:

Along the way, I discovered that (with the exception of the epoxy putty, which just would not work for such tiny fixes…not enough surface area to effect a good bond) none of the putties I have bond to this resin formulation. That meant I had to use small fragments of the resin that had to be removed to fill the small bubble holes:

I dry-fit the components to see how they fit and, mostly, they do, but later on there will be some fitting to get the resin parts to match the kit parts at the nacelles correctly:

Yeah, so, I like what I see! If I can paint this correctly, the parts should look tres chic! So I started by laying out the colors with the parts they’re going onto:

And then I got the paint onto the parts:

Now painted, pastels created the sense of reality. The inside of the vanes was painted Tamiya’s X-32 Titanium Silver and over painted with Tamiya’s TS-80 Flat Clear (rattle-can) so that the pastels would stick. The inner surface of the afterburner body and the conical flame holder were painted Vallejo’s Model Air 71.132 Aged White, and the turbine blades were painted a mixture of Mr. Hobby’s H76 Burnt Iron and Tamiya’s XF-2 Flat White before having the blade edges dry-brushed with silver. Once the paint all dried, I used dark orange, medium gray, light gray, and black pastels to create the “cooked” look:

Before and after:

Then black paint, Tamiya XF-1 Flat Black, needed to go on while I still had easy access to the parts:

Once the paint had dried, I scraped off just enough paint from the face of the “fins”  for the vane mounts to have some surface to glue onto:

And then I’m reminded of why I generally do not do any work in the morning until the coffee percolates upwards into where my brain used to be.

I dropped one of the assemblies and took a nick out of one edge:

Y’know…the edge that was painted and had pastels applied. That edge.

Ever quick on the uptake (yeah, right), I finished my coffee. Silently. No cursing, screaming, or scared cat kind of quiet. I knew it was time to fix the nick once I figured out how to fix the nick. Glue a small piece of resin into it:

Then use a SHARP knife to whittle the resin into obscurity (because dull knives tend to tear plugs out), add a dab of paint and a touch of pastel (the inside of the former nick is in the second photo):

From every photo I’ve seen of the Blackbird while it’s parked, either at active airfields or in museums, the control surfaces at the trailing edges of the wings droop slightly. I cut the inner control surfaces away from the inner wings so that means I have to do the outer wings:

This time, I added a sheet of .030″ (.762mm) styrene to the inside of each wing. Before adding them, I scored the length and bent them along the scored line to the approximate angle I want the control surfaces to droop:

I like the way that worked so well, I’m going to do it to the inner wings as well.

Again, I’d done SO much work fitting parts and pieces that I was losing sight of the state of my work. This time, instead of using proper primer, I used a rattle-can of Tamiya’s TS-6 Flat Black rattle-can to check fit and if I can paint this without packing up the grills I spent so much damned time fitting:

Yep…worked just fine… Very glad to know I can get those grills to display!

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