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Super Scale Radial Engine — Building a turn powerhouse for a P-47

With electric motors now being used some-more frequently in scale models, we have new possibilities for enhancing a model’s appearance. Because they’re probably quivering giveaway and run cleanly, they concede any manikin engine and engine mountain to be assembled around them and all from straightforwardly accessible home seminar materials. we indispensable such a manikin engine for my converted 81-inch-span Hangar 9 P-47 Thunderbolt. In this article, we uncover we how we achieved this.


When we bought a model’s Hacker A60-L outrunner motor, we also purchased a engine mountain designed for it. As crafty and as lightweight as this mountain is (it is entirely tractable and includes a support for a behind temperament of a motor), we could see that it would be really formidable to censor a massive section behind a manikin engine though carrying to review to an prolongation shaft, that we always try to avoid. With such a gaping manifest opening in a front of a cowl, we wanted to urge a model’s scale appearance, so we motionless not to use it. Instead, we built a plywood cone-shaped manikin crankcase that a engine is cumulative to a front of and that also includes a backplate that can be radial-mounted to a bulkhead. The backplate also accepts a granted flanged behind temperament used to support a utterly substantial overhang of a A60-L motor.

With a engine and manikin crankcase mountain cumulative to a model, it all felt clever and firm enough, so we ran a engine to check for problems. From a 95-percent charge, we see ì2900Wî on a Wattmeter (almost 4hp) and a solid 6,300rpm on a 22◊10 APC E propeller though a spirit of a problem. So far, so good!

To cold a motor, a granted centrifugal fan pulls atmosphere in by 4 holes in a front of a manikin crankcase. This afterwards passes by a windings and magnets and exits by 4 radial slots conflicting a fan and also a behind of a backplate. The warmed atmosphere afterwards spills into a cover and out of a indication by a semi-open cover gills.

The crankcase is done out of formers built adult regulating laminations of 1/16-inch-thick manipulate that are afterwards wrapped with dual layers of 1/32-inch-thick manipulate with skinny CA used to bond all together. A lite-ply nose ring is glued to a front and sanded to mix with a cone, and afterwards a whole structure is strengthened with a covering of potion cloth practical to a outside. More 1/16-inch-thick manipulate laminations are used to build a backplate, holding caring to safeguard that a behind temperament is mainly placed and does not connect with a behind of a motor. An opening is compulsory on a front underside of a mountain for a 3 engine cables, though this can be dark from perspective with a manikin crankcase sump screwed over a exit. With a engine now successfully mounted and dark in a manikin crankcase, it was time to consider about how to supplement a remaining detail.


It was a service to review that a Williams Bros. accessories were behind in production. The 2-inch, scale, Wasp cylinders used in a manikin engine come away finished and embody a pushrods and cylinder bottom used to mountain them on a plywood flange. The print also shows a nuts and brief lengths of screw threads glued into a prong former and spark-plug wires shaped out of cosmetic pushrod tubing.


The well-engineered, though bulky, engine mountain that a total manikin engine and new mountain replaces.

The vital components for a manikin crankcaseóall from laminations of 1/32-and 1/16-inch-thick birch plywood.

The crankcase and backplate with a Hacker outrunner engine in place.

The finished cylinder-mounting prong with a cylinders glued to it. The remaining engine components are also visible.

The embellished crankcase display how a cylinder ascent prong is prevented from relocating forwards by a dual magnetos and a distributor.

The finished manikin Wasp engine with a Hacker A60-L outrunner engine commissioned inside a crankcase and with a spinner attached.

When we finished a manikin crankcase, a hunt on a Web found that a once taken Williams Bros. Wasp engine cylinders are now being constructed again (lucky indeed!). These apparently save an huge volume of work while also bestowing a really picturesque coming on a engine. Soon, 9 scale Wasp cylinders were on a approach to me.

At this stage, we didn’t know if, indeed, a finished engine would fit in a Thunderbolt’s cowl. As it incited out, we had to lop any cylinder by 3/16 in. before gluing them to their cylinder bases that I, in turn, had glued to a rim of a ascent prong done of laminations of 1/64-inch-thick manipulate wrapped around a former.

This “cassette” of cylinders afterwards slips over a front and onto a together apportionment of a crankcase and is defended by a manikin magnetos and a distributor.

The magnetos, distributor and sump are built out of laminations of skinny lite-ply. Building in laminations allows we to simply incorporate recesses that assistance censor a heads of a screws that secure a equipment in holes drilled in a crankcase. The shaped threads are strengthened with skinny CA.

Small nuts with brief lengths of screw threads are used to paint a studs and nuts that shaft a crankcase halves together, and they are glued around a flanged former. Finally, we used cosmetic pushrod tubing to copy spark-plug wiring.

I practical 5 or 6 coats of sanding sealant to all of a wooden components in discerning succession. This effectively coats all with a plastic-like aspect that usually took one brushed cloak of gray finish to tinge over. The finish is not ideal though some-more like a casting it is meant to represent. we sprayed a cylinders with aluminum paint and afterwards with a small matte black to tinge them down.

The surprisingly tough engine mountain has survived a deteriorate of drifting and we have gifted no overheating problems with a Hacker motor. The manikin engine and mountain though a engine import 8 ounces, and to fit within a cover of my Thunderbolt, it measures 7æ inches in hole over a widest point. As explained previously, we had to digest a cylinders somewhat to grasp this, so technically, we am drifting on a high-revving, short-stroke Wasp engine!


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