First run in 1937, the R-2800 was America's first 18-cylinder radial engine design. The Double Wasp was more powerful than the world's only other modern eighteen, the Gnome Rhône 18L of 3,442 in³ (56.4 L), but it was much smaller and heat dissipation was a greater problem. To enable more efficient cooling, the usual practice of casting or forging the cylinder head cooling fins that had been effective enough for other engine designs was discarded, and instead, much thinner and closer-pitched cooling fins were machined from the solid metal of the head forging. The fins were all cut at the same time by a gang of milling saws, automatically guided as it fed across the head in such a way that the bottom of the grooves rose and fell to make the roots of the fins follow the contour of the head. Cylinder cooling was effected by aluminium cooling muffs that were shrunk onto the steel alloy forged barrels. In addition to requiring a new cylinder head design, the Double Wasp was probably the most difficult to effectively direct a flow of cooling air around.
When the R-2800 was introduced in 1939 it was capable of producing 2,000 hp (1,500 kW), for a specific power value of 0.71 hp/in³ (32.6 kW/L). No other air-cooled engine came close to this figure, and even liquid-cooled ones barely matched it. The designing of conventional air-cooled radial engines had become so scientific and systematic by then that the Double Wasp was introduced at a power rating that was not amenable to anything like the developmental power increases that had been common with earlier engines. Nevertheless, in 1941 the power output of production models increased to 2,100 hp (1,600 kW), and to 2,400 hp (1,800 kW) late in the war. However, even more was coaxed from experimental models, with fan-cooled subtypes producing 2,800 hp (2,100 kW), but in general the R-2800 was a rather highly developed power plant right from the beginning.
The R-2800 was used to power several types of fighters and medium bombers during the war, notably the F4U Corsair, with the first prototype Corsair becoming the first-ever single-engine US fighter plane to exceed 400 mph (640 km/h) in level flight during October 1940. The R-2800 also powered the Corsair's naval rival, the F6F Hellcat, the P-47 Thunderbolt the twin-engine B-26 Marauder and A-26 Invader, as well as the first purpose-built twin-engine radar-equipped night fighter, the P-61 Black Widow. When the US entered the war in December 1941 there were very quickly some major changes in philosophy, and such long-established engines as the Wright Cyclone and Double Wasp were re-rated on fuel of much higher octane rating (anti-knock value) to give considerably more power, and by 1944 versions of the R-2800 powering late-model P-47s (and other aircraft) had a rating (experimental) of 2,800 hp on 115-grade fuel with water injection.
After World War II, the engine was used in the Korean War, and surplus World War II aircraft powered by the Double Wasp served with other countries well past the Korean War, some being retired as late as the latter part of the 1960s when the aircraft were replaced. Engines naturally grow in power with development, but a major war demands the utmost performance from engines fitted to aircraft whose life in front-line service was unlikely to exceed 50 hours' flying, over a period of only a month or two. In peace time however, the call was for reliability over a period of perhaps a dozen years, and the R-2800's reliability commended its use for long-range patrol aircraft and for the DC-6, martin4-0-4, and Convair transports. This last application is noteworthy, since these were twin-engine aircraft of size, passenger capacity, and high wing loading comparable with the DC-4 and the first Constellations.
Today, more than seventy years after the first Double Wasp was built, it is still used in many restored vintage war bird aircraft displayed at air shows, and sees frequent service worldwide on aircraft such as the Canadair CL-215 water-bomber. In addition, many R-2800s continue to power DC-6 cargo and fuel-carrying aircraft in locations such as Alaska. A total of 125,334 R-2800 engines were produced between 1939 and 1960.
The Brassin parts are safely contained in the transparent plastic blister packaging. The rein parts have two layers of sponge to absorb any jolts and the photo etched fret is backed by black card and is secured with tape. Now that’s what you call excellent packaging. Inside you will find: Resin
-1 x reduction gear housing with the two distributor housings either side of the magneto.
-1 x forward bank of cylinders and the front of the rear bank of cylinders.
-1 x rear bank of cylinders and exhaust pipes.
-1 x locating pin for the two rows of cylinders.
-2 x access covers from the upper engine nacelle. Photo etched
-1 x ignition harness.
-6 x lengths of internal framework.
-1 x 6 page construction guide.
First impression is the quality of the resin casting. The nicely defined detail around the first bank of engine cylinders particularly the cooling fins and the push rods. Looking at the second bank of cylinders I was dismayed to find no sign of any of the same detail. I have I duff set of resin castings? The answer is no, if you look very carefully, the second row of cylinders can just be seen between the first bank of cylinders. The second bank of cylinders provides the detail for the cylinder heads and exhaust pipes. The exhaust pipes have shallow holes in them providing extra interest. A shaped resin pin is pushed through both banks of cylinders and this ensures that the two banks of cylinders are correctly aligned. The one piece photo etched ignition harness finishes of the detail.
The housing for the propeller reduction gear is separate and has the magneto and the two distributor housings cast onto it. Also included is the propeller shaft. Again there is some excellent detail to be seen. All the main resin parts are attached to substantial resin blocks that needs to be removed with a razor saw or fine hacksaw blade. Eduard has provided plenty of spare resin so that you can cut with a good margin of error and sand the excess away.
The two resin access covers are beautifully thin. They are attached to their casting blocks by an extremely thin film of resin. The photo etched framing is nicely done and has fine etched holes along their length.
Obviously there is a bit of surgery necessary to show off all the lovely detail. The engine mount on the fuselage need shortening by 1.3 mm and the exhaust detail needs to be sanded away. On the cowling itself the access hatches needs to be cut away and the areas where the exhaust pipe emerges from the rear of the cowling needs to be trimmed. When this is done the photo etched framework needs to be added.
Full instructions are provided and they are very clear. One thing that is missing is any guidance about colours, but there is plenty of reference material out there.
This is a great release from Eduard and certainly will add a whole lot of interest to the 1/72 Hellcat kits. Obviously some surgery is required, but it does look fairly straightforward. The extra effort will be well worth it.
Highs: Excellent detail, sensible break down of parts.Lows: Lack of colour reference.Verdict: The kits plastic Pratt & Whitney engine is very good, but if you fancy revealing the engine to show more detail, this is the way to go. Highly recommended.