The Wargamer

23 July 2017

Historical Article: Born in Battle Forged in Steel and Aluminium

The US Strategic Bombing Campaign of Japan June 1944 - August 1945, Part 1

Published on 15 JAN 2015 7:25am by John Dudek
  1. world war ii, air combat, strategic, background / research material, english

Looming out of the warm spring darkness, a bomber stream formation of 68 US Army Air Force four engine Boeing B-29 Superfortress heavy bombers made landfall well over the Japanese home island of Kyushu around midnight on 15 June 1944.  The formation's lead plane was piloted by Brigadier General Laverne G. Saunders.  Japanese searchlights with their multi-million candlelight arcs snapped on ahead of them in the distance, sending up numerous probing shafts of ultra brilliant light skyward searching for the oncoming bombers.  The plane's navigator spoke.  "General, we're approaching the target and are on the bomb run."   In response. Saunders said. "Bombardier, the plane is now under your control."  "Roger!" the bombardier replied.  The man sitting in the "greenhouse" glass nose of the plane and gave the "OK signal" with his hand held over his head. He then leaned over his Norden bombsight and began making minute adjustments to the plane's course and speed; all the while fighting the only recently discovered high altitude jet stream winds that buffeted the bomber and all others in the formation.  Tail winds with this speed and velocity could propel a high flying aircraft to over 500 mph while a head wind could slow their progress down to a crawl. Either eventuality could easily spoil the bombardier's aim. The bomber's target was the Imperial Japanese Iron and Steel Works at Yawata.  Heavy but inaccurate flak artillery fire exploded brightly around the bomber stream but caused little to no damage.  In addition, there were no Japanese night fighter planes anywhere in sight. The bombardier soon called out "Bombs away!" as the first of 107 tons of bombs cascaded downward towards the steel works.  The bomber formation effected a long, lazy turn away from the target to return to their newly built air bases in Nationalist China.  The bombing mission appeared to have been a success.  However, subsequent photo reconnaissance flights sadly revealed poor results from the raid with only one bomb striking within the industrial complex due to both the high speed jet stream winds and poor visibility over the target.  However, this fact was mitigated by the knowledge that the raid on Yawata was the first aerial bombing raid on mainland Japanese since the pin-prick Doolittle aircraft carrier launched air raid over two years before.  The US news media was absolutely elated by the news of the Yawata bombing raid, proclaiming that this was but the first of many more air raids that would soon knock Japan completely out of the war.  For once they were completely correct.

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From the start to the finish of its illustrious wartime career, the B-29 Superfortress has been called the most revolutionary aircraft produced, fully developed and deployed into the fiery crucible of combat during WWII.  Most historians fully agree the reason the Japanese surrendered in September 1945 was because of the utter devastation and total destruction of their nations industries, the laying waste of nearly all of their major and secondary cities, plus the mining of all their major waterways.  This led to the country being reduced to near famine by the time the atomic bombs were finally dropped on Hiroshima and Nagasaki in August 1945.  The one inescapable fact is the B-29 was largely responsible for virtually all of these brutal conditions being fully implemented and met.  The odd fact is the B-29 project was almost cancelled while still in its earliest developmental stages because of all the revolutionary aspects and innovations being built into its construction.  Built as a continuing successor to the VLR (Very Long Range) bomber project, the B-29 was seen as the successor to the Boeing B-17 and B-24 heavy bombers then in full production in early WWII and continuing for the remainder of the war.  The need for a third heavy bomber seemed a waste of time, material and talent to many in the Army Air Force chain of command and it was only though the continued direct insistence of visionary men like US Air Force Commanding General Henry "Hap" Arnold that the B-29 Superfortress' continued development was allowed to proceed.  Arnold fully supported the project and staked his entire military career on the B-29's eventual success in carrying out its war time mission of the destruction of Imperial Japan's homeland cities and its war machine. The B-29 was designed as a high altitude bomber of extremely long range endurance; one that could carry a large pay load of bombs to targets throughout the Pacific and deliver them without the need of any protecting escorting fighter planes.  The plane would be fully pressurized and heated to optimize both its crew's comfort and combat effectiveness even while flying at extremely high altitudes.  Whereas the B-17 and B-24 bomber crews fighting in the European Theatre of Operations wore heated suits and several layers of clothing into combat in the extremely cold and harsh flying conditions of their unpressurized planes over the wintry skies of Germany and Italy. Meanwhile the men of the 20th Air Force B-29's in the Pacific oftentimes wore but light cotton khaki clothing and visor baseball caps on their heads while going into battle. Another truly revolutionary innovation in the B-29's development was the use of innovative remote gun control computers, rather than traditional manned gun turrets to protect the bomber from air attacks from enemy fighter planes. The weapons were aimed from five separate sighting stations located in the tail and nose as well as from three Perspex blisters in the plane's fuselage. Each of the five, two-gun Browning M2 50 caliber gun turrets was sighted electronically using five state of the art General Electric analog computers, one dedicated to each sight that greatly increased the weapon's accuracy by compensating for factors such as air speed, lead, gravity, temperature and humidity.  The computers also allowed a single gunner to operate two or more turrets (including tail guns) simultaneously.  The gunner in the upper position acted as fire control officer, managing the distribution of turrets among the other gunners during combat.

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Every new plane has a number of developmental glitches that need to be fixed or changed. Without a doubt, the greatest of the new plane's worst "teething problems" came from the aircraft's new Wright R-3350 Duplex Cyclone radial engines.  Literally rushed from the designer’s drawing boards into full production practically overnight, the engine was beset by a number of potentially dangerous problems.  The worst of which was the tendency for the engine to overheat and swallow one of its valves in flight, seizing up the engine and causing a potentially catastrophic engine fire to break out. During one such early test flight from the Boeing bomber plant, the second prototype B-29 suffered a critical engine fire in flight, causing the bomber to crash into a nearby meat packing warehouse, killing 19 civilians as well as the bomber's entire crew.  A number of Generals in Washington immediately called for the plane's cancelation.  Nonetheless, General Arnold instead ordered the plane to be placed into full production in early 1943 while measures were devised to correct the B-29's engine problems and all the other normal developmental quirks found in such a high strung but potentially war winning aircraft. Interim measures included cuffs placed on propeller blades to divert a greater flow of cooling air into the intakes which had baffles installed to direct a stream of air onto the exhaust valves.  Oil flow to the valves was also increased, asbestos baffles installed around rubber fittings to prevent oil loss, thorough pre-flight inspections made to detect unseated valves, and frequent replacement of the uppermost cylinders (every 25 hours of engine time and a full change of engines every 75 hours.

As these corrections continued, it is important to take stock of the new bomber and imagine the incredible feat the plane's designers and builders were able to achieve in record time.  The entire B-29 project was something never before seen in the history of aviation.  Normally such a truly revolutionary concept plane went from idea stage to drawing board to the first prototype in a time frame of five years.  The people at Boeing brought the plane into full production and deployment in less than three years from its inception in 1940, despite all of the plane's unexpected and expected teething problems. These were soon fixed or at least remedied. In addition, all of this was somehow brought about by successfully combining the design engineering, production and flight testing of the plane all at nearly the same time.  The first prototype took off and flew on 21 September 1942. General Arnold immediately ordered 175 of the new B-29 bombers to be ready for combat by mid spring of 1943.

Fully loaded with crew, fuel and bombs, the B-29 could fly at 31,850 feet at a top speed of 350mph. and had a maximum range of 3,250 miles.  Most Japanese fighter planes of the day could not even achieve that altitude and of the ones that did, most were not fitted with the necessary turbo superchargers that would enable them to intercept and attack the speeding B-29 bombers.  As a result, the B-29's greatest enemy were Japan's anti- aircraft guns on the ground, and only the heaviest of these could even reach the bomber's maximum operating altitude.  What's more, unlike the Germans, the Japanese did not have effective gunnery radar nor proximity shell fuses in their arsenal's inventory.  They relied primarily upon sound detecting devices and gunnery telescope sighting devices during the daylight hours, and searchlights during the night to combat any raiding enemy bombers. By the fall of 1943 General Arnold had his new B-29 bombers and their trained air crews at the ready, but needed airfields on islands within easy striking distance of the Japanese homeland. The American military advance in the Pacific hadn't yet advanced close enough to any island chains within flight distance of Japan.  The idea for "Operation Matterhorn" and its basing of B-29's in China was first put forth during the Casablanca Conference in January 1943.  A few months later the Anglo-American Combined Chiefs of Staff decided on a US central Pacific naval drive to seize the Mariana Islands.  These islands would provide the badly needed springboard necessary to base and fly B-29's from during their coming air raids on the Japanese home islands. Much more importantly, the Mariana Islands could be easily and regularly supplied by the US Navy, unlike China where everything had to be trans-shipped by air over the high Himalaya Mountains.  The first B-29 bombers based there literally had to make a number of ferrying trip hops back and forth over the mountains just to carry enough bombs and fuel to mount the first of their bombing missions.  American President Roosevelt agreed on this temporary expedient of using China as a base for the bombers because he was eager to begin the systematic and strategic air bombing of Japan, even though the B-29's could only reach the Japanese southern island of Kyushu from their far off Indian and Chinese air bases.  General Arnold too supported that decision as but a temporary solution to the matter, although he preferred the US Navy plan of seizing the Mariana's as soon as possible to build massive B-29 airfields on the three major islands of Saipan, Guam and Tinian and base his bombers there.  Only then could a war ending bombing campaign be successfully waged against Imperial Japan.


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