Published ET-Aviation & Defence Review Feb 2019, http://etadfr.timesgroup.com/February19/
The Development of the Carrier Based Aircraft
“1,000 bombardment airplanes can be built and operated for about the price of one battleship”
General Billy Mitchell, United States Army Air Corps,
In the early part of the twentieth century, the presence of battleships had an intimidating psychological and diplomatic impact upon the country which faced the onslaught of these fast battleships armed with ten 12-inch guns and hull protection plates. In order to counter this concentrated naval force, an opponent needed means of locating enemy ships beyond the range of the visible horizon. Locating enemy ships much earlier would allow some time to present a layered defence of torpedo boats, mines and shore-based guns against the oncoming fleet. The warning could be achieved by scouting forces like smaller faster ships & boats and the scouting aircraft. The vision of aircraft with scouting ranges far larger than the reach of the battleships and their guns, when compared with the much slower scout ships, provided a valuable standoff option at scrambling up a better defence. Added to this were the concepts of arming the aircraft with bombs/torpedoes which could destroy enemy ships far away from the own coastline, and also that of crippling adversary’s ships operating such aircraft. The technological advances of the period and the idea of aircraft as a standalone weapon catapulted the development of the Naval Aviation.
The US Navy had been authorised by the government to purchase aircraft for spotting purposes by early 1908, and subsequently, it was also decided to provide space for aircraft on scout ships. The term scout planes referred to a fast, light and unarmed reconnaissance aircraft, which, in later years, were also outfitted with forward firing machine guns.
It was appreciated that the aircraft were going to play a significant role in Naval Operations in future. The US Navy established Organised Air Service in 1913. However, with the looming WW I, it was clear that Naval aircraft requirements would not be met through civil manufacturers; therefore, it was decided to establish a dedicated Naval Aircraft factory for development of prototypes and transferring the designs to the industry. The Royal Navy in the interim had retrofitted many ships to carry aircraft and had also built an aircraft carrier. The Americans and the British even worked together in 1917-18 to build aircraft carriers. The Royal Navy envisioned many additional roles for the aircraft such as torpedo carriers & fighters in addition to those of scouting & spotting. The aircraft of that era needed technological breakthroughs to mature into a full-fledged independently fieldable weapon. The planes were unable to carry large bomb loads off the deck of the ship and had abysmal communication with the mother ship; pilots had to rely upon homing pigeons for delivering the report of ship sightings. Novel operations using aircraft like dive bombing, aerial refuelling and instrumental flying were being attempted. Naval Aviation also faced stiff resistance from the battleship admirals who believed that the relevance of battleships would not be over with the advent of Naval Aircraft and Aircraft Carriers.
One of the earliest references to the design of Torpedo Carrying Aircraft is found in the lecture of Major Bumpus at the Royal Aeronautical Society and the Institution of Aeronautical Engineers on 15 December 1927. The advantages of a torpedo plane versus a ship launching a torpedo were many firstly, that of the much higher speeds of the aircraft enabled a torpedo attack on the enemy ships at much larger ranges than what the own ships could do. Secondly, the torpedo plane presented a smaller and a faster manoeuvring target for the enemy’s anti-aircraft guns, and thirdly it was a far cheaper option in case of a fatal hit as compared to the loss of a ship both in psychological and economic terms. In the early twentieth century, it was postulated that a torpedo aircraft would fly very high, then dive and settle to a much lesser height to avoid detection and after that launch the torpedo when the target came within the striking range of the torpedo. Such a craft would also have to execute dodging moves to evade enemy fire as it returned to ship or a land base. Those days the torpedoes were straight/zigzag runners so for accurate firing on a single ship the aircraft would have had to align itself accurately on a moving target, chances of a hit were better when attacking a group of ships since the combined manoeuvring by the ships was a much slower affair. Many torpedo planes were designed and patented in that period these included the Short 200 h.p., Short 225 h.p., Sopwith-Blackburn “Cuckoo” in 1917, the Blackburn “Swift” of 1920, and others like the Avro “Buffalo” and the Blackburn “Ripon” of 1926.
The design of torpedo planes proceeded along two lines namely that of planes taking off and landing from aircraft carriers and that of the flying boat type carrying two torpedoes on each side. The aircraft intended for carrier operations were guided by restrictions of space on board the carrier and its hangars this, in turn, limited the number of aircraft that could be operated from the carrier. The flying boats could land at a vantage point in the sea and await the target for carrying out an attack. The main design issue then was the likely imbalance caused due to discharging of only one torpedo at a time instead of both simultaneously.
In the United States; based upon recommendations of the Naval War College, NWC; it was decided to design aircraft carriers such that the aircraft could be serviced and armed on the deck in open ventilated hangars rather than inside the closed hangars. The NWC also recommended building large and high-speed aircraft carriers of around 23, 000 tons and having speeds of up to 33 knots. The Congress approved the procurement of 1000 planes. As for the type of aircraft, the concept of a single scout/bomber/fighter was not accepted, and a mix of fighter planes, battleship/cruiser spotters, scout/reconnaissance planes, dive bombers, level bombers, torpedo planes and patrol seaplanes were considered.
The technical issues which had been resolved had pertained to the launch of a large number of aircraft from the carrier, shifting of planes in dark as well as bad weather, refuelling/arming of planes, and damages due to arresting gear. By the 1930s, the torpedo aircraft had been developed sufficiently and could carry a ~2000 lb torpedo, further, the dive bomber too could launch two ~100 lb bombs. However, the warships had also improved their anti-aircraft capabilities and could cause severe damage to the attacking planes. Higher speeds, longer ranges and greater payloads were needed to make Naval Aircraft a true force multiplier. Towards the end of the 1930s came the Curtiss dive bomber SBC-4 which could fly ~405 miles with a ~1000 lb bomb at a speed of ~240 mph. It also had 1×0.30 in (7.62 mm) forward-firing M1919 Browning machine gun and 1×0.30 in (7.62 mm) flexible rearward-firing machine gun. It had a 950 hp R-1820-34 engine.
This type of aircraft required greater take-off and landing speeds which led to changes in the design of the aircraft carriers. The Aircraft Carrier with planes of the SBC-4 generation became a formidable stand-alone weapon system whose aircraft could now deliver crippling ordnance for incapacitating the enemy warships. These new types of aircraft could carry out different missions like scouting at long ranges and of larger areas by carrying additional fuel tanks or taking bombs instead of fuel for an attack on ships at lesser ranges. The development of new aircraft opened a new horizon of great capabilities for the Carrier Strike Force as it could launch planes which could not only scout as well as attack the enemy ships but also the enemy’s aircraft carriers.
On Sunday, the 7th of December 1941, at 7:58 A.M., a radio warning “Air raid, Pearl Harbor!” “This is no drill! This is no drill!” was broadcast to all ships in the harbour. Pearl Harbor, Hawaii, is nearly 4,000 miles from Japan and about 2,000 miles from the U.S. mainland. Japanese warplanes had launched their torpedoes and dropped their bombs on the US naval base at Oahu. The Commander-in-chief of the Pacific fleet broadcast a second warning: “From CINCPAC to all ships Hawaii area: Air raid on Pearl Harbor. This is no drill.” This message was picked up at The Navy radio station at Mare Island Navy Yard, San Francisco.
The attack had commenced at 7:48 a.m. Hawaiian Time. The base was attacked by 353 Imperial Japanese aircraft (including fighters, level and dive bombers, and torpedo bombers) in two waves, launched from six Japanese aircraft carriers. All eight U.S. Navy battleships in the harbour were damaged, and four sunk. The Japanese also sank or damaged three cruisers, three destroyers, an anti-aircraft training ship, and one minelayer. One hundred eighty-eight U.S. aircraft were destroyed, 2,403 Americans were killed, and 1,178 others were wounded. The three American carriers assigned to the Pacific Fleet escaped the attack as they were not in the harbour on that fateful day.
The Japanese had operationalised a multi-aircraft carrier attack, a strike mode the United States had been debating since 1927. The era of Naval Aviation had entrenched itself.
“Yesterday, December 7, 1941 — a date which will live in infamy — the United States of America was suddenly and deliberately attacked by naval and air forces of the Empire of Japan.”
President Franklin D. Roosevelt