DELIBERATE DITCHING IN THE JAMES

Transcription

1 DELIBERATE DITCHING IN THE JAMES September 20, 1944 ~ The Necessity ~ One of most successful and heavily produced of heavy bombers used by the US Army Air Corps during World War II was the B-24 'Liberator'. The US Navy also used a variation of this basic airframe, called the PB4Y-2 'Privateer'. But like all aircraft, this type of bomber had it faults. One of the more serious of which was its tendency to break apart and sink within minutes, when ditched at sea [ditching was defined by the military as an emergency landing of a land based aircraft on water]. Numerous battle-damaged B-24's were unable to make it back to their bases in England from missions over Europe and were lost in the English Channel. When these aircraft went down, their crews often were killed or injured on impact. Even if they got out of their aircraft, crew members could...and often did...drown in the notoriously rough waters between France and England. In a several month period in late 1943 and early 1944, fifty B-24's were ditched in the English Channel. Thirty-one of these aircraft broke into two or more pieces on impact, and 24% of their crew members drowned. It was obvious that the Army Air Corps needed to develop better procedures for pilots to follow in such emergencies. So, as the predecessor to the US Air Force so often did during World War II, the air arm of the US Army turned to the researchers at the Langley Memorial Aeronautical Laboratory (LMAL) for help.

2 ~The Aircraft ~ By 1940 standards, the four-engined B-24 was a huge aircraft. It had a wingspan of 110 feet and a fuselage length of almost 68 feet. Empty weight was 36,500 pounds. Fueled and loaded with a bomb load of 8,000 pounds, it weighed as much as 65,000 pounds at take-off. A crew of eleven was required to fly and defend this aircraft, which bristled with ten machine guns. It could fly as high as 28,000 feet and had a range, albeit with a reduced bomb load, of 2,100 miles. Pilots of that era said it was more difficult to fly than the better-known B-17 Flying Fortress. ~ The Preliminaries ~ The US Army Air Corps and NACA [the National Advisory Committee for Aeronautics; predecessor of NASA] enjoyed a close relationship at Langley Field on the Virginia Peninsula. NACA facilities there included wind tunnels, a large towing tank, hangers and numerous shops and support facilities which were located within easy walking distance from the air corps' flight line. To get started, NACA researchers and engineers analyzed written reports of a number of B-24 involuntary water landings. A scale model of the aircraft was then created and subjected to a series of simulated ditching in one of NACA's two towing tanks. While those tests were useful, NACA and Army officials concluded that the only way they could determine how a B-24 would behave upon impact was to observe and record an actual ditching of full-sized airplane under controlled conditions. So they set out to do just that. 2

3 ~ The Preparations ~ The Army Air Corps made a 'war weary' B-24 available for modification and testing by NACA. Typically, during the latter stages of World War II, bombers that had made a large number of missions or had been damaged were retired and often subjected to metal reclamation. In the summer of 1944, the 'Ellie Mae', a veteran of many combat hours was flown to Langley Field. In preparation of a full-scale ditching experiment, this aircraft was painted bright yellow and had black lines added to its fuselage, apparently to make impact results and any damage more visible during filming of the unusual event. With a touch of typical, irrepressible humor, Ellie Mae's nose art was painted over, but replaced by the silhouette of a human figure superimposed on a donut's outline and about to be dunked in a coffee cup [quite visible in the above photo] for the forthcoming test. More tests using two additional B-24s were planned, if deemed necessary; hence the 'No 1' lettering beneath the coffee cup. Other more pertinent and extensive modifications were also made. The aged warplane's weaponry was removed, including the gun turrets in the airplane's nose and atop her fuselage, aft of the cockpit area. An escape hatch was fitted in the opening left after the top turret assembly was removed. The thin aluminum skin that constituted the former Ellie Mae's underside was beefed up by adding a 1/8th thick layer of steel plating. For purposes of the test the aircraft was set up for a crew of just two; a pilot and a copilot. Their flight positions were protected by adding some structural bracing, plus floatation material was incorporated in the cockpit area. A number of instruments were installed inside the B-24 to record deceleration and pressures imposed by a water landing. The instruments were placed in watertight boxes that also contained buoyant material. These containers were painted bright red to help in recovery, should they become detached. The pilot selected for the test was Major Julian Harvey of the Army Air Corps who, at the time was assigned to one of the Army Air Corps' proving grounds. A qualified B-24 pilot, he had previously flown 29 combat missions over war-torn Europe. His copilot was Colonel Carl Greene, Langley Field's liaison with NACA. 3

4 Mid-morning, Wednesday, September 20, 1944, Major Harvey and Colonel Greene climbed into the cockpit of the modified B-24. The steel plating that reinforced the belly of their aircraft also covered the normal means of doing so. Apparently, based on the following photo taken just before the start of the test flight, they climbed through the cockpit windows to get to their flight station. ~ The Ditching Site ~ After a routine take-off from Langley Field, they flew a few miles southwest to the selected ditching site; a stretch of the James River on the upstream side and parallel to the original James River Bridge. That structure was located upstream of the present-day bridge [what remains is currently used as a fishing pier]. The electrical transmission towers and connecting cabling that parallel the new bridge did not exist in The pre-world War II photograph on the right is marked to indicate the general location of the ditching site. Records do not indicate why that particular site was chosen. Presumably, it was because of the relatively shallow water that existed at the ditching site, which would make recovery easier if the aircraft sunk. Plus, the bridge structure provided a good impediment to prevent the aircraft, after ditching, from floating away downstream due to the river's normal flow. Another factor, perhaps, were the excellent vantage points provided by the bridge for NACA and military observers. 4

5 ~ The Approach ~ The test was scheduled to take place before noon on September 20, But a persistent ground fog that morning kept visibility in that area down to a half mile. Consequently the ditching was delayed for roughly an hour, until the pilots were confident they could make a safe approach. To fulfill the test requirements, they had to fly low and slow over the Newport News side of the river. That meant passing over a very populated area that included Ferguson Park, a World War II housing development and Parkview Elementary School on a school day. The pilots were also expected to ditch their aircraft fairly close to a small fleet of supporting boats. One of these was a 'crash boat' from Langley; there to rescue the pilots if the aircraft sank. These speedy watercraft were often dispatched to the scene of aircraft accidents in the Chesapeake Bay. They had originally been US Navy PT Boats. A typical crash boat appears in the image on the right. Navy support for the test was in the form of a barge mounted crane, capable of lifting the bomber from the water. Other boats and even an escorting NACA aircraft were used as floating camera platforms, both still and movie, and to provide Army Air Corps, US Navy and NACA officials a close-up view of the test. Observers and cameramen were stationed on the bridge for similar purposes. Presumably, the bridge was closed to civilian vehicular use at that time and the Coast Guard surely was employed to kept curious boaters well clear of the test area and the airplane's approach path. But it was impossible to keep the event secret, or to prevent people from gathering along the shoreline to gawk and speculate as the B-24 passed low overhead several times. After making a few practice runs to align the aircraft properly a safe distance and parallel to the James River Bridge, Major Harvey brought her across the river's shoreline with engines throttled back to a barely flyable speed of 100 MPH. With flaps down, tricycle landing gear fully retracted and nose at an upward angle, the tail of brightly colored test aircraft touched the water's surface after passing over the ship channel. It was on target, close to floating markers there to help guide the pilots to the desired ditching location in water thirty feet deep. 5

6 ~ The Dunking ~ A vintage NACA film, which lasts about ten minutes, covers the experiment from take-off to aircraft recovery. Well worth watching, it is available at the following link: The two representative images on the right were captured by a high speed camera and are a part of that fairly technical film. As graphically depicted from several additional angles in the film, the aircraft made a slight skip after first impact by the fuselage's tail. When the tail hit the water again more solidly, the B-24's nose and left wing plowed into the river, tossing debris skyward. A huge cloud of spray initially hid the plane from the view of anxious observers. At the time of impact, onboard instruments recorded an air speed of 97 MPH and a deceleration force of 2.6 g's. The aircraft weighed 44,100 pounds, heavier than normal without a bomb load due to the steel reinforcement on the bottom of the airframe. The B-24 traveled 435 feet after touching the water's surface until it came to rest. Portions of the wing and tail surfaces, and two of the plane's four propellers were ripped off, and the aircraft's steel-reinforced belly was badly damaged. The worst damage was a structural failure of the fuselage just forward of the wing, as shown in the photo on the left. Taken shortly after the plane had come to rest, it shows the test pilots emerging unharmed. To protect themselves during the water landing, they had worn what appears on film to be 40s' vintage football helmets. Major Harvey is the individual shown in the above image emerging from the escape hatch. In a film close-up, after standing up he is shown calmly reaching into his pocket, pulling out a comb and attending to his 'helmet hair' before climbing aboard the Army boat depicted above that had rushed to the scene. Neither pilot was injured, or even got wet. 6

7 ~ The Physical Results & Analyses ~ As pre-planned, floatation devices were placed under the B-24's wings within minutes after the ditching. Although the fuselage was visibly distorted, it was not completely severed. The Navy crane that was standing by was employed to lift the aircraft out of the water, providing a clear view of the steel-reinforced belly of the aircraft. They were shocked by the extent of the damage. The B-24 was then placed on a barge and towed to Langley Field for further inspection and a detailed damage investigation by NACA. In addition to the external damage, they found considerable distortion to the aircraft's interior, in spite of structural reinforcements made for the test. If a normal air crew of eleven had been onboard, injuries and perhaps even deaths would have likely occurred. Follow-up testing was conducted at the Langley lab. The model previously used was creatively modified. Its fuselage was hinged just forward of the wing and weights were utilized to cause the model to careen to the left, when propelled by a catapult located near NACA's towing tanks, into the Back River. Film of those tests compared favorably with the results of the full scale test. Other aircraft types, both military and civilian were later modeled and tested at the Langley lab. Another bomber, albeit one guided by remote control was deliberately ditched by NACA in San Francisco Bay a few years after World War II had ended. Reams of resultant data were collected and analyzed, and a comprehensive report was issued in 1957 that included all these tests' results plus recommendations for future large aircraft design and operation. 7

8 ~ The 'Bible' ~ Even today, that 1957 NACA report is considered the definitive document on the subject of aircraft ditching. Design recommendations included in it resulted in major changes to aircraft structural design that have proven to be beneficial in a number of forced landings on the water by both military and civilian multi-engine aircraft. In addition, the recommended procedures contained in the report have been replicated countless times in pilot training and aircraft operational manuals. Aviation engineers and pilots alike often simply refer to it as 'The Bible'. ~ The Legacy ~ Perhaps the best example of the benefits of that 1944 deliberate ditching in the James are reflected by what happened on January 15, 2009; the day when 'The Miracle on the Hudson" took place. As the world now knows, "Sully" Sullenberger, a former US Air Force and a very skilled airline pilot, glided a crippled passenger liner to a safe water landing and saved all of the 155 passengers and crew that were onboard. Film of that forced water landing looks remarkably like the 1944 images contained and referenced in this essay. Of course, neither Major Harvey...nor Colonel Greene...nor any NACA engineers were in the cockpit with Sully Sullenberger in Or...where they...??? 8