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Pratt & Whitney Wasp R-1340

Mach Turtle

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I'll be building the Williams Brothers kit depicting the Pratt & Whitney Wasp R-1340 radial engine in 1/6 scale. This engine first flew in December, 1925, and was supremely successful. Its variants were in production through the 1950s, and more than a few remain in commercial service today.

It's not as zoomy as some of the other prototypes underway here, but as engineering work the Wasp outlasted most of them.

Here's the boxtop:


I've made a modest start by assembling the basic carburetor.


You can see there are some gaps and seams; I'll take care of those next.

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Thanks, Doug. The cylinders need to have a bare metal finish, for sure, and I don't have an airbrush. I am thinking about spraying with Tamiya Light Gun Metal (TS-42) and applying some washes to highlight the cooling fins.

I have made a little start, assembling the two-part basic cylinders...


...and parts of the case:


Fit is okay; there is a considerable amount of flash and a few voids.

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  • 3 weeks later...

I'll be watching this one,always fancied one of these,being a fan of WB kits. :popcorn:

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That's a great stand. Did you just improvise, or is it based on a real design? I assume it's of extruded styrene rod -- or maybe wood?

In any case, it's far better than the plastic "plaque" that comes with the kit. That's already been recycled here, and I was thinking about how to do the mounting when I am done. I was kind of leaning toward suspending it from my ceiling with fishing line, like my other models, and saying it was an early stealth design.

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MT: I sketched the stand that I saw in an engine overhaul shop and scalwd it to fit the Wasp. There are mounting pins in the vertical members which fit into the motor mount holes. The wiring is #32 from an electrical supp;y shop

The stand was built from square Evergreen stock with .040" re-inforcements

Barney http://www.barneysairforce.com

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Thanks, Barney. Nice website.

I have the push rods in place now:


They were a little fiddly, and there are still some gaps, but I think it will clean up well in the end.

Behind the scenes, I have the rest of the crankcase coming together.

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Here's some more progress. I have the back of the crankcase in place now, as well as the valve covers:


Here's the front view. The spinner is just temporarily in place; I need to sand some seams there.


Fit is all right. Drilling out all those holes for the intake pipes was hard to do well, and I still need to fill some gaps here and there.

Overall, though, I like the way it looks.

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Thanks for your comments! I am learning a lot by watching everyone else's projects here.

I added some details yesterday:

Gun synchronizers, magneto mounts, and covers...


Oil pump...




...and carburetor details:


The next step, as soon as I finish filling gaps (like around the top of the oil sump) and touching up paint, will be washes to bring out details, particularly on that big, gray carburetor. I want to give Flory Models' products a try -- they seem popular and well reviewed.

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The washes arrived from Flory Models. I've used the Black wash to treat the carburetor and crankcase. I've assembled those two major subassemblies, and added the magneto casings as well.

Back view:






The washes take some getting used to -- I have found that they, being water-based, can bead in strange ways on surfaces painted with acrylic. But they're very forgiving and I think I will be able to acheive a good result.

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Try adding a tiny bit of dishwashing detergent to your wash mix. It seems to help with the surface tension and the beading up on a slick surface.


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It doesn't have to be dishwashing detergent. All you need is one tiny drop of some form of soap. It can be liquid hand soap, which is my preferred medium since it isn't as concentrated as dishwashing soap. It breaks the surface tension of the droplets.

This is looking really good!

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Thanks, Barney.

Heres's some more progress. It's parts-complete, except for the wiring and the mount.

This one shows the aluminum fuel line, magneto timing link (paint to be fixed), and the tube that holds part of the wiring loom (green, with all the little holes):


This one...


...shows the oil filler pipe (which I had to reinforce with brass tubing and wire), as well as the fuel line.

The rocker pivots aren't aligned right in many cases.

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  • 2 weeks later...

Sorry to be slow to post. I have a lot happening these days and not as much time for modeling as I would like. Of course, I like the other stuff too.

Enough philosophizing. I have tackled the core of the wiring harness, attaching the various ignition leads to the arc-shaped guide channel.


If you care to look at my earlier posts on this engine, you will see that the guide was attached without the wires. This was a mistake, and I had to pop it off again to do the wiring.


I drilled all the attachment points with a 1.3 mm bit, which enabled me to more or less press-fit the wires in place before cementing them with cyanoacrylate.

Here's a front view, in which you can see the nice vinyl boots that come with the kit for attachment to the plugs:


I think I have cut too short the leads that are supposed to go from the rear of the guide to the magnetos. I am not sure what I'm going to do about that.

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