JR Potts, AUS 173d AB and Dan Alex (Updated: 1/14/2016):
As launched, the USS Hornet showcased an appearance much like today's modern US naval carriers. The bulk of her topside was dominated by a large-spanning flight deck that was serviced by three hangar elevators with access to the aircraft decks below. Three hydraulic catapults were in use allowing for three aircraft to be launched simultaneously (two on the main deck and one at the hangar deck). The island superstructure was offset to the starboard side in the usual fashion, providing an unrestricted approach at both the bow and stern for incoming and outgoing aircraft. Her internals housed crew areas, mess halls, machinery shops and engine controls. Propulsion was served through 4 x Parsons geared steam turbines mated to 9 x Babcock and Wilcox boilers feeding 4 x shafts at the stern. This arrangement provided the carrier with a speed of 32.5 knots in ideal conditions and a range out to 12,500 nautical miles. She was crewed by 2,919 personnel during the peak of her wartime use.
The USS Hornet was originally fitted with 8 x 5"/48 (130mm) caliber Dual-Purpose (DP) guns for self-defense. These were backed by 16 x 1.1"/75 caliber (28mm) anti-aircraft cannon in a 4x4 turret arrangement. Final defense was through 24 x M2 Browning .50 caliber heavy machine guns. In February of 1942, the armament suite was revised to 8 x 5"/38 DP guns, 16 x 1.1" (4x4) cannons and 30 x 20mm AA cannons. In July of 1942, the suite was once again modified to become 8 x 5"/38 DP guns, 20 x 1.1" (4x4) cannons and 32 x 20mm AA guns.
However, the true bread-and-butter of a carrier vessel was in her fleet of aircraft whose potency was only realized when launched. The USS Hornet carried a mix of 90 aircraft usually distributed as a fighting force made up of fighters, torpedo bombers and dive bombers. This allowed the carrier the unmatched capability to respond to all manner of situations as required - whether patrolling or engaging enemy over the sea, on the sea or under it - when far away from friendly soil. Additionally, carriers were most always sent into battle with a protective force of surface warships charged with its very protection - they providing a network of anti-aircraft, anti-ship and anti-submarine measures to ensure the carrier lived to see another fighting day. This is what made aircraft carriers of World War 2 even more feared than the once-grand big-gunner, steel battleships appearing at the turn of the century. The age of the battleship effectively ended with the arrival of the aircraft carrier.
USS Hornet steamed down the Virginia coast during sea trials on December 7th, 1941 when the Imperial Japanese Navy (IJN) attacked Pearl Harbor, officially sending the United States into war. Nazi Germany then declared war on the United States and her U-boat submarines regularly patrolled along the Atlantic Coast. Hornet was sent to the Gulf of Mexico for her final shakedown cruise and, upon her return to the Norfolk Navy base on February 2nd, 1943, two US Army Air Force B-25 Mitchell medium bombers were hoisted onto her flight deck. She sailed out to sea and launched them successfully - the first time Army bombers had ever taken off from a Navy carrier. The crew was instructed not to discuss this secret launching.
Hornet made some crew changes and was fueled and supplied before departing Norfolk on March 4th with San Diego as her destination. She arrived there March 20th, mooring on North Island to receive aircraft. Air Group 8 squadrons received upgraded aircraft: Fighting 8 (VF-8) received the F4F-4 Wildcat fighter while Bombing 8 (VB-8) and Scouting 8 (VS-8) received the SBD-3 Dauntless dive bomber. Torpedo 8 (VT-8) remained with the outdated, but easy to fly, Douglas TBD-1 Devastator due to a delay in the delivery of the new Grumman TBF-1 Avenger torpedo planes. Hornet then left North Island and steamed off the coast of California while qualifying her pilots for carrier launches and landings. Captain Mitscher received top secret orders that would take Hornet on a delayed route to Pearl Harbor. Hornet sailed north to Alameda Naval Air Station for additional aircraft identified in Mitscher's secret orders.
The Doolittle Raid
For the upcoming mission, the Army required bombers with a cruising range of 2,400 nautical miles (4,400 km) that could carry a 2,000-pound (910 kg) bomb load. The bombers looked at were the Martin B-26 Marauder, the Douglas B-18 Bolo and B-23 Dragon, and the North American B-25. The B-26 showcased takeoff problems from a short carrier deck while the B-23 Dragon had a wing span that was half as big as the B-25. This would reduce the number of aircraft that could be stored on deck of the carrier. The B-18 and the B-25 were the final two considered by commander Jimmy Doolittle; however the North American B-25B Mitchell's wing span was shorter and was finally chosen to carry out the mission.
Twenty-four of the group's B-25B Mitchell bombers needed to have revisions completed before the mission and they were sent to the Mid-Continent Airlines modification center in Minneapolis, Minnesota. Steel blast plates were mounted on the fuselage around the top turret (expecting fire from above). Atlantic weather required installation of deicers and anti-icers. One of the radio sets and the lower gun turret (as well as one crew) was removed to save weight and make more space for fuel (and thusly range). Three additional fuel tanks were added to increase fuel capacity from 646 to 1,141 U.S. gallons. Fake gun barrels were fitted onto the tail section as a rouse to enemy interceptors. Replacement of the secret Norden bombsight was necessary in case a bomber was forced down over Japan so a low tech replacement was constructed by pilot Capt. C. Ross Greening with materials that cost only 20 cents. When completed, the 24 B-25's were flown to Eglin Field in Florida for pilot carrier take-off training on March 1st, 1942.