SoCal Dive, Wreck

F4U-4 Corsair Engine (Detail)

by Brett Eldridge

In my mind, the Corsair is one of the “symbols” of US air supremacy in WW2. It is a beautiful airplane that struck a balance between power, weight, maneuverability, east of maintenance, etc. The pilot sits very far back in the plane behind the engine, wings and a large fuel tank and so it has a very distinctive silhouette.

Corsair F4U

According to the excellent reference book America’s Hundred Thousand by Francis H. Dean, there were about 11,500 Corsairs produced between 1942-1945. Think about that for just a minute.

By the end of 1944, Chance Vought was turning out 300 Corsairs a month, or one complete airplane every 82 minutes.  A total of 5,380 F4U’s were built during the year.”

Vought website

The F4U Corsair engine

The primary power plant of the Corsair was a 2,300 hp 18 cylinder Pratt & Whitney Double Wasp radial engine (R-2800-32W), That same engine was used in a LOT of different airplanes during that era. It was the very definition of a “workhorse.”

WW2 naval planes tended to use radial engines since they were designed to be air cooled (vs water cooled for in-line engines). The tradeoff is weight vs drag. The radial engine has a higher drag but is lower weight because it doesn’t require a radiator and cooling fluid vs. the in-line engine which has a lower drag but have more parts (points of failure and vulnerability to enemy fire). Some additional background:

The Vought F4U Corsair was used in the military by both the Navy and Marines. It is a radial engine fighter known for both its bent wings and its unique sound. The corsair was 33′ 4 long, 16′ 1 high and had a wingspan of 41′. It had an empty weight of 8,982 lbs and a gross weight of 14,000 lbs. The f4u corsair used one Pratt and Whitney R-2800 engine which produced 2200 – 2300 hp. The corsair had a cruise speed of 182 mph, a max speed of 417 mph and a max climb rate of 2,890 ft/min. The corsairs maximum range was 1,015 miles.

Wikipedia

As mentioned, the engine is 18 cylinders with two rows of 9 cylinders each. Below are some close-up pictures showing the pistons around the radius of the engine block along with some pictures of the engine block, supercharger gears, etc:

I ran across an interesting fact during my research. The “2800” in the model number refers to the swept volume in cubic inches (2804) and that EACH of the 18 cylinders displaces as much as an entire Subaru Outback engine! Those are some massive pistons.

One of the things you might notice is that the pistons are “popped out” of the cylinders. This is normal in aircraft wrecks. You can see similar in the photos I took of the P-38 inline engines in San Diego.

Those massive cooling fins (the engine was air-cooled) and cylinder heads decay and rot pretty quickly in saltwater which leaves the cylinders open with the head bolts in place and stainless valves laying around.

Propeller & “-4” Version identification

The UB-88 team first identified the wreck and identified the “version” of the Corsair due to the 4 bladed propeller. Before the “-4” version, the propellers were all three blades. You can see in the image below the single propeller still on the engine but that the other mount is 90 degrees offset (instead of 120 degrees)

Note that you can also see the reduction gears in between the engine block and the propeller.

There were about 2,400 of the -4 version of the Corsair built.

Supercharger

Behind the propeller and engine block you can see a shaft and some gears. Those two opposing “gears” are impellers for the turbo supercharger. I’ve included some schematics (one from the UB88 site) and some photos I found to show the reader what it looks like “on land.”

Overall, the Corsair is a beautiful plane which helped the US achieve air superiority in WW2. The engine is one of the most prevalent from that era and a marvel of engineering. This specific wreck really gives the diver a chance to view the engine in a unique way that you probably won’t find anywhere else.

References

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