Grumman F6F-3 of VF-12 prepares to launch from the USS Saratoga
The Pratt & Whitney R-2800 Double Wasp engine was the beating heart of the Grumman F6F Hellcat, contributing to its reputation as a formidable fighter during World War II. This 18-cylinder, twin-row radial engine was known for its power, resilience, and reliability, playing a crucial role in the Hellcat’s success in combat.
Engine Evolution and Power Output:
Initial Design Choice: The Hellcat was initially designed to be powered by the Wright R-2600 radial engine, which produced around 1,700 horsepower. However, after observing early aerial battles in Europe and the Pacific, it became clear that more power was needed to create a competitive and effective fighter.
Upgrade to the Pratt & Whitney R-2800: The R-2800 Double Wasp was chosen for its 2,000 horsepower at sea level and its proven reliability in other aircraft like the P-47 Thunderbolt and Vought F4U Corsair. This engine was key to the Hellcat’s performance, allowing it to reach speeds exceeding 400 mph.
Durability: The R-2800 engine gained a reputation for being incredibly rugged. It was common for Hellcats to return to base or carriers after sustaining severe engine damage, such as shattered cylinders or ripped oil lines. Even with significant oil loss, the air-cooled radial engine could continue functioning long enough to get pilots back to safety.
Water Injection System: Later models, such as the F6F-5 Hellcat, included a water and alcohol injection system (R-2800-10W). This system allowed the engine to produce short bursts of 2,250 horsepower, significantly enhancing its performance during critical moments in combat.
R-2800 Engine Variants in the Hellcat:
F6F-3 Hellcat: Powered by the R-2800-10 engine, which produced 2,000 horsepower at takeoff and 1,650 horsepower at 22,500 feet. Many of these engines were retrofitted with water injection systems to increase their output.
F6F-5 Hellcat: This variant came equipped with the R-2800-10W engine, capable of 2,250 horsepower with water injection. This upgrade gave the Hellcat improved performance over its earlier versions.
XF6F-6 Hellcat: The experimental final version of the Hellcat, first flown in July 1944, featured an R-2800-18W “C-series” engine with a four-bladed propeller. These aircraft were the fastest Hellcats, capable of reaching speeds of 417 mph at 20,000 feet, with 2,380 horsepower in short bursts. However, the war ended before the XF6F-6 could enter production.
Technical Specifications of the R-2800:
- Weight: Approximately 2,450 pounds empty.
- Displacement: 2,804 cubic inches.
- Cylinder Bore: 5.75 inches.
- Stroke: 6 inches.
- RPM Range: The engine operated at between 13,000 and 27,000 rpm, depending on the flight phase.
Starting the R-2800 Engine:
Starting the Hellcat’s engine involved a detailed, 13-step procedure. A starting cartridge, which worked like a small explosion, ignited the engine, often causing a distinctive cloud of blue smoke. If the engine didn’t start, the crew could load another cartridge and try again. Cold weather or tough conditions sometimes required multiple attempts, with the crewmen pulling the propeller manually to build compression.
Operational Procedures:
Once the engine started, the pilot advanced the mixture lever to “auto rich” and turned the primer off. He had to closely monitor the oil pressure, ensuring it reached at least 200 pounds per square inch within 30 seconds. If not, the engine had to be shut down immediately to avoid damage.
The Pratt & Whitney R-2800 made the Hellcat not only fast but resilient, giving pilots confidence in their ability to handle both aerial combat and return safely, even with significant engine damage. This engine, with its reliable design and adaptability, was a key factor in the Hellcat’s dominant role in the Pacific Theater.