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...huge World War II establishment to a much smaller force, and started their engagement in the four-decade long Cold War. In the first years of the next decade the new service found itself fighting a different, difficult, and frustrating war in Korea. Throughout this period, flying performance was the primary concern. Compared to these issues, flying safety was of much lower priority.
Flying safety is an important, yet neglected, aspect of aviation history. The romance, the daring, the spectacle, the records, the performance of flying and fliers are the focus of attention, not the ordinary or the negative. Since 1921, the first year the army airmen kept comprehensive records, their flying accident rate has declined. This has not been a straight-line trend, however, as the rate shot upward in a number of years, notably in 1941, when America began the buildup for World War II and in 1946 during the rapid demobilization following that conflict. It then resumed its downward movement even during the hectic Korean War expansion. By the end of that conflict in 1953, the airmen had cut in half the rate of major accidents from the prewar low in 1940 to the lowest yet registered. (2) (figure 13) This dramatic drop in the accident rate suggests that the airman adapted well in the conversion to jet power. Does this observation hold up under closer scrutiny? How much credit does the USAF deserve for this improvement?
Hardware
Jet propulsion offered the airmen several advantages in addition to higher performance. For example, tricycle landing gear, which quickly became the standard configuration on jets, enhanced aircraft safety as it eliminated ground loops on landing and gave the pilot better visibility during ground operations. Jet engines simplified flying with torque-less power, less complex engines, and an absence of propellers. Jet engines had only a throttle, while piston engines had controls for the throttle, mixture, and prop.
Of course, there were, trade-offs. Performance was higher, as were takeoff, approach, and landing speeds. (4) Higher speeds meant not only less time for pilots to react, but due to faster vertical change, increased altimeter lag, which gave the pilot erroneous altitude information. (5) Jet engines were new to Air Force pilots and ground crews. Flying characteristics were different, for example, compared with prop aircraft, jet aircraft decelerated relatively slowly when the throttle was retarded. (Speed brakes were added to provide additional drag to slow jet aircraft more rapidly.) On the other hand, a particularly dangerous aspect of flying jets was that it took some time for jet engines to deliver increased power ("spool up") unlike prop engines that delivered power almost immediately on demand. One early (1948)jet flight manual emphasized: "The acceleration characteristics of a jet-propelled airplane are definitely inferior to those of a propeller-driven airplane." (6) Another peril was that advancing the throttle too rapidly could cause a jet engine to "flame out" and lose all power. In addition, jet engines were prone to suck up foreign objects and damage their internal workings. (7) Tricycle landing gear was novel to most pilots and posed the possibility of dragging the tail when landing. (8)
U.S airmen transitioned quickly to jet aircraft. The first American jet, the, P-59, flew in October 1942 and the first jet fighter introduced into service (P-80) made its maiden flight in January 1944. (9) In the last half of 1949 jet fighter flying hours in the USAF exceeded prop fighter flying hours for the first time and in 1953 87 percent of USAF fighter flying hours were logged in jets. (The switch to jet bombers was somewhat slower; as only 7 percent of USAF bomber flying hours in 1953 was in jets; and it wasn't until the last quarter of 1957 that jet bomber flying hours exceeded prop bomber flying hours.) (10)
The Air Force put three jet fighters into service following World War II and into combat in Korea (1950-53). America's first jet fighter, the P-59, was not one of these. With a top speed less than that for piston powered fighters of the day, Bell built only 66 of the planes and none equipped operational units. Instead the better performing Lockheed P-80 Shooting Star became the Air Force's first service jet fighter. The USAF accepted about 1,600 of the fighter and reconnaissance versions and employed it in combat almost until the end of the Korean War. Meanwhile, the Republic P-84 Thunderjet made its maiden flight in February 1946, while the North American P-86 Sabre first flew in October 1947. (11)
Was this transition to jet power a revolution or evolution, were the jets something entirely new or just another aircraft, albeit with higher performance? Chuck Yeager, the renowned test pilot, stated after first flying a jet that it was "like trying to learn how to ride a race horse after riding only on elephants." (12) Nevertheless the Air Force adopted the evolutionary view and as a consequence took few additional efforts to integrate the new technology. In any case, jet fighters had problems.
Aircraft Problems: F-80
The first major issue with the Shooting Star involved the power boosted aileron controls. (Controls in previous aircraft were unboosted, but the jets' higher speeds required greater control forces which meant that pilots needed additional help.) When operating normally the F-80's system permitted a roll rate of 135 degrees per second, however, when inoperative the fighter's roll rate was reduced to less than 12 degrees a second; put another way, without aileron boost stick forces increased fifteen fold. In September 1947 the service attributed four major accidents to loss of lateral control and suspected this as the cause in five other accidents. Three of the first 29 fatal F-80 accidents were caused by loss of control. The problem was that the F-80's hydraulic system could not provide adequate pressure for aileron boost when other hydraulic systems were operating (such as the landing gear or speed brakes). Lockheed's design was flawed and the USAF response was worse. When a crew chief in one RF-80 unit found that a larger hydraulic accumulator from an RB-26 would fit nicely on the Shooting Star and solve the problem, the responsible Air Force agency, Air Materiel Command, would not authorize the "fix." Instead it told the unit to "proceed at their own risk" and did not circulate the information to other F-80 outfits. Only belatedly did the Air Force begin modifying the system in 1948 by substituting a larger accumulator to provide more hydraulic pressure, but this modification took some time. (13)
Another F-80 vulnerability was a weak horizontal stabilizer. An Air Force communication in fall 1950 stated that the "F-80 fatal crash at Nellis AFB 9 October [19]50 has conclusively established this is a repetition of the same type of structural failure which has caused 8 crashes and is the probable cause of 3 additional crashes this year." (14) The message went on to note that tail failure might account for the loss of three F-80s that did not pull out of dives in Korean combat, crashes the USAF had blamed on enemy ground fire. The authors of the message vented their frustration as they urged immediate and rapid testing of the problem, otherwise "This directorate feels unable to contribute further to the reduction of this type of F-80 crashes beyond maintaining a bookkeeping record of wrecks and fatalities until repeat until active interest and cooperation by responsible agencies is demonstrated by immediate remedial action." (15) In January 1952, an F-80 turning onto final approach went out of control, crashed, and killed the pilot. The accident board concluded the fatal accident was caused by either pilot error or the failure of the horizontal stabilizer, for at this time not all F-80 tails had been reinforced. (16) Lockheed had failed to meet the greater demands on the aircraft's airframe and control system and, along with the Air Force, was slow to react to these shortcomings.
Aircraft Problems: F-84
Perhaps the most disconcerting of the F-84's problems was losing wings. This flew in the face of the aircraft's rugged appearance and the reputation of its manufacturer (Republic) that built the P-47, undoubtedly the toughest fighter of World War II. The Air Force knew of this situation as early as 1948, when tests revealed that the wing construction was "the main source of difficulty with the airplane." (17) The fifth fatal broken wing accident (August 1950) prompted the accident board to write, "Although this type aircraft has a history indicating [that] wing failures in flight are not uncommon, it is felt that this trouble does not exist until the 'g' limits are exceeded." Nevertheless, the report ended with the damning recommendation that "future fighter aircraft [should] be designed in such a manner that ordinary gunnery passes can be made with a high degree of safety and confidence and with a minimum possibility of shedding wings." (18) Following the ninth fatal accident caused by a wing ripping off the aircraft, Air Materiel Command tested the structural strength of "war weary" F-84s and concluded that wing failure was caused by high speed pull-up in excess of specific limits noted in the technical order, in short, pilot error. Therefore, it recommended that "No further engineering action is indicated." (19) After the twelfth fatal accident attributed to...
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