Document created: 26 July 01
Air University Review, May-June 1981
How many seats?
Major William A. Flanagan
A scribbled message on the blackboard in a fighter squadron briefing room contained the words, "Star Wars showed the back-seater can be replaced by a machine." Spacecraft designs seen in such dramas as Star Wars, Flash Gordon, and Battle-star Galactica depict single-seat fighters knifing into enemy formations as the pilots multiple, computer-generated displays inundate him with torrents of vital information. Introduction of the F-15, F-16, and A-10 into the Air Force inventory apparently confirms the merit of the single-seat tactical aircraft. But is the single-seat fighter really the panacea suggested by the movies? In light of contemporary technology and the threat, is it possible that a two-seat F-15 might actually be a better fighter than the singleseater?
The first fighters were two-seaters flown in World War I. One man flew the airplane, and the other fired the machine gun. These airplanes were somewhat underpowered since the rotary engines of the period could produce only 80 to 115 horsepower. Although the designers pared the weight of the airframes to 1000 pounds, further means were sought to lighten the machines even more. Eliminating the second man and his equipment was an obvious method. The synchronized machine gun that fired through the propeller arc revolutionized the fighter. With it a single pilot could aim the gun by pointing the entire airplane at the target. Lighter, more maneuverable singleseaters appeared such as the Sopwith Camel, Spad, and Fokker Dr. I triplane. The image of the lone fighter pilot as the "knight of the skies" emerged, fostered by the popular press and government publications as a welcome relief from the carnage of trench warfare. Toward the end of that war the two-seat fighter appeared again briefly. New lightweight engines rated at over 200 horsepower made possible single-seat performance while carrying an aft-facing gunner in addition to the pilot. The most respected British fighter in 1918 was a two-seat airplane, the Bristol F.2B, the only World War I British combat aircraft to remain in service until the 1930s.1
In the 1920s and early 1930s, the two-seat fighter generally seemed to be on the verge of extinction as the air forces of the world concentrated on the singleseater. The increased speeds of aircraft made it difficult for a rear gunner to aim his weapons due to increased wind force; an enclosed turret had to be installed with its attendant weight, drag, and complexity. Vertigo and G-forces during maneuvering also lessened the effectiveness of the aft-facing gunner. The U.S. Army Air Corps tested and discarded the two-seat Detroit-Consolidated P-30. The Royal Air Force built the Boulton-Paul Defiant with a power-operated four-gun turret, but unfortunately its success was limited by the lack of forward-firing guns. Additionally, its lack of performance and maneuverability relegated it to bomber interceptor and target-towing duties. The German Luftwaffe introduced a multiseat, multiengined fighter, the Messerschmitt Bf 110. The aircraft, designed as a long-range bomber escort, was necessarily large in order to accommodate extra fuel; hence, the airframe was also large enough to allow for a gunner. But, in the Battle of Britain, the highly maneuverable single-seat, single-engine Hawker Hurricane and Supermarine Spitfire soon proved that the German escort fighter itself needed an escort. The gunner with his single or two barrel machine gun was relatively ineffective against the eight guns of his agile attacker. The Germans withdrew the Bf 110 from daylight operations over England. At night, however, the Bf 110 proved ideal.2
The use of bomber fleets at night and the development of airborne radar led to a new use for the two-seat, twin-engine fighter. The pilot flew this fighter while the second man searched for targets with the aircrafts radar. When he located a target, the radar operator directed the aircraft to a position where the pilot could visually attack. Since dogfights were impossible at night, the large night fighters lack of maneuverability was not important. Even so, by the end of the war, large 2000-plus horsepower piston engines allowed large night fighters, such as the P-61, to achieve performance comparable to that of the single-seat Mustang and Hellcat.3 But the introduction of the Messerschmitt Me 262 jet fighter signaled the advent of the jet-engine revolution for combat aircraft.
Like piston engine technology at the beginning of World War I, jet engine technology in the late 1940s was rudimentary. Designers kept the airframe small in order to maximize the performance benefits of the early, crude jet engines. To accommodate the weight of the radar operator and his equipment, fighter development followed two parallel courses leading to the maneuverable day fighter (F-80 and F-86) and the heavier two-seat, radar-equipped bomber interceptors. The F-86 was the primary day fighter at the beginning of the Korean War, and the primary night fighter was the piston-engine F-82 Twin Mustang. As engine technology continued to mature, the early 1950s saw the introduction of the two-seat F-89 Scorpion and F-94 Starfire designed to intercept such prop-driven bombers as the Russian Tupolev Tu-20 Bear. These interceptors were still somewhat underpowered. Since the Soviets were beginning to develop jet bombers, something had to be done to increase interceptor performance. Again attention focused on deleting the second crew member. Work began on a computerized fire control system that allowed the pilot to operate the radar and provided steering and firing commands for intercept. After numerous development problems, the F-86D Sabre and F-102 Delta Dagger entered service equipped with the new fire control system.4
By the mid-1950s, the possibility of all-out nuclear warfare between the United States and the Soviet Union signaled changes in the role of the fighter. It was now perceived as a bomber interceptor and delivery system for nuclear weapons. The advent of air-to-air missiles also colored perceptions of the fighter role. Hence, the Air Force concentrated on developing interceptors (F-101, F-106), fighter-bombers (F-100, F-l05), and a lone single-seat air superiority fighter (F-104). The U.S. Navy developed the F-4 Phantom, a fighter that could fly long-range combat air patrol and use missiles to intercept threats to the attack carrier force.
The 1960s saw jet fighters being used, not in nuclear wars but in conventional limited wars in the Middle East and Southeast Asia. Fighter aircraft engaged other fighters in the battle for air superiority. The classic maneuvering dogfight reappeared as pilots discovered that often long-range missiles shots were not feasible because of missile limitations or target identification problems. The cannon again became important since dogfights often produced situations where the enemy fighter was too close or too agile to be hit with a missile. Thus, at levels of conflict below nuclear war, there was still a requirement for an air superiority fighter to control airspace. To fulfill the air superiority role, the Air Force modified the F-4 Phantom to carry an internal cannon besides its air-to-air missiles. The F-4 destroyed 130 MiGs during the Vietnam War and became the most successful fighter of that period.
In late 1965, however, the Air Force requested industry proposals for a new air superiority fighter. The design requirements drew heavily on Southeast Asia combat experience. The new fighter was required to have exceptional maneuverability, high speed, and a capability to launch radar-guided or heat-seeking air-to-air missiles. By September 1968, the requirement also specified one-man operation of the avionics systems, a major change from the proven two-seat F-4 then in use. This requirement eventually resulted in development of the F- 15 Eagle, which will serve as the USAFs primary air superiority fighter into the 1990s.5 In 1972 the United States Air Force requested industry to build a lightweight, maneuverable aircraft prototype in order to evaluate the current aircraft state of the art. The aircraft was to be a clear-weather fighter with emphasis on maneuverability and low cost. By 1976 this prototype had metamorphosed into the single-seat F-16 "swing force" fighter with a primary mission as fighter-bomber and a secondary role of air superiority. Thus, the Air Force enters the 1980s with an air superiority force consisting largely of single-seat fighters.
Technology (especially engine technology) has often driven the choice between single and two-seat fighters in the past. What changes in technology have occurred that might influence the designer or operators choice?
A comparison of the modern fighter with the World War II fighter shows striking differences in size. The F-15 is 64 feet long and weighs 40,000 pounds; the P-51 Mustang was 32 feet long and weighed 9200 pounds. The change in size is due mainly to the increased performance required of the modern fighter. The F-15 engines develop enough thrust for the aircraft to reach a top speed of mach 2.5 (1650 miles per hour) at altitudes up to 70,000 feet. The P-51 attained a top speed of 437 miles per hour at 25,000 feet. The drag to be overcome by the thrust of the engines increases with the square of the speed; therefore, if speed is doubled, the drag is quadrupled. Furthermore, as an aircraft maneuvers in a dogfight and the G-forces increase, the drag increases even more, and the thrust required to maintain speed must match the increased drag. The engines and the fuel necessary to feed them are main factors in determining the size of the fighter. Furthermore, good maneuverability requires the lighter to have a low wing loading (weight of the airplane divided by the wing surface area). Thus, the fighter must be lightweight (often impossible due to other mission requirements), or it must have a large wing surface. All these factors combine to produce a modern jet fighter significantly larger than its World War II predecessor.
Armament has also changed the form of the fighter aircraft. The P-51 was equipped with six .50 caliber machine guns, and most gun firings in World War II were conducted at ranges of 600 feet or less.6 The F-15 is equipped with a cannon that has only a slightly greater effective range than the machine guns, but its principal weapons are air-to-air missiles with ranges measured in miles rather than yards. The AIM-7 Sparrow radar-guided missile can be fired in all weather conditions at ranges beyond 10 miles. The AIM-9 Sidewinder is a smaller heat-seeker missile useless in clouds, but it still has a range of 2 to 5 miles.7 A radar set is necessary to extend a pilots search capability to ensure the most effective use of these weapons. A second man operated the radar in the F-4, but computers have replaced the second man in the F-15. The computers filter out the target from the radar background clutter and display only targets on the pilots radar display. All controls for the F-15 radar are placed on the stick or throttles so the pilot can control the aircraft while operating the radar. Once the pilot selects a target for attack and "locks on," the computer computes and displays the targets range, altitude, and closure and provides steering instructions for the intercept. A symbol on the pilots gunsight indicates where the target should appear visually as the range decreases.8
The F-15 fire control system is well suited for the pilot location and attack of a single target. Attention today however, has shifted from the Southeast Asia limited air combat scenario to the target-rich Central European front. The shift affects the future employment of the air superiority fighter dramatically.
A war between NATO and the Warsaw Pact in Central Europe would produce the most intense air battle in history, an air battle in which NATO forces would be heavily outnumbered. With 6000 to 8000 daily combat sorties over Germany predicted by some sources, the air superiority fighter will face its most severe challenge.9 The F-15 will face a numerically superior enemy in heavily contested airspace where communication jamming will probably reduce the effectiveness of fighter command and control. A comparison of relative strength in the area underscores the intensity of the struggle. Fifteen Soviet and East German fighter regiments (the equivalent of American wings) are deployed in East Germany alone. Conversely, NATO deploys the equivalent of only seven wings in Germany, Belgium, the Netherlands, and Denmark combined.10 F-15 production is projected at 729 aircraft, but, according to present estimates, the Soviets have more than 1500 late-model MiG-21s and 1000 MiG-23/27s in service. Soviet military aircraft production continues at 1150 per year versus the U.S. quota of 500 aircraft.11 The numbers point to one conclusion: the F-15 will operate in an area where the enemy enjoys numerical superiority.
The Air Force fighter community has begun to accept this fact and is examining changes in fighter tactics. An article written by an F-15 pilot for an official publication reflects the new concept of operations against large enemy fighter formations.12 The pilot uses the F-15 radar to assess the enemy formation. He then uses the best intercept tactics possible to maximize surprise and get off the first shot. One or two targets in the formation are quickly attacked. The F-15 then departs the battle lest the hunter become the hunted. Under this concept, the classic dogfight turning engagements that occurred in Southeast Asia will be unlikely to develop in Central Europe, since an F-15 in a turning fight is easier to see and its flightpath is more easily predictable. The success of the attack will rely largely on the intercept (first) phase and the separation (last) phase. In light of the anticipated air battle scenario, an objective evaluation of the two-seat F-15 would be most prudent.
The most obvious advantage of a two-man crew is the division of labor in the cockpit. A two-man crew is less easily saturated as the workload increases due to enemy threats or malfunctioning equipment. A 1975 Hughes Aircraft Company study13 evaluated single-seat and two-seat cockpits in simulated air-to-ground strike missions. The simulated missions were unique in the sense that the crew had to react to threats displayed on the cockpit radar warning receiver (RWR) as well as threats that appeared outside the cockpit. Some of the latter threats also appeared on the RWR display, but others did not, which reflected the real-world situation of a visual attack by an enemy with his radar turned off. Crews in the simulator had to focus their attention inside and outside the cockpit in a situation similar to air-to-air combat. The results showed no significant difference in performance between one- and two-man crews when they were presented with threats only displayed on the RWR. When outside-the-cockpit threats were introduced, the two-man crew was significantly superior (40 to 95 percent) in performing the mission tasks and simultaneously detecting the threat. The second crewman was a decided advantage for visual surveillance outside the cockpit because he could share the work inside the cockpit and allow more time for important visual scanning.14
The increased lookout capability of the two-man crew demonstrated in the simulator is especially important for an air superiority fighter. Throughout the history of aerial combat, one fact has never changed: most pilots were shot down without being aware of the presence of the attacker. The VIII Fighter Command included the following underlined sentence in its tactics manual dated 29 May 1944. "Remember few pilots are shot down by enemies they see."15 In Vietnam unseen MiGs accounted for an estimated 80 percent of all air-to-air losses.16 Since the two-man crew is better able to search outside the cockpit in situations that impose high workloads, the second crew member minimizes the risk of an unseen attack and maximizes the probability of survival.
The division of workload possible with a two-man crew provides more benefits than survivability. As described earlier, the F-15 must contend with numerically superior perhaps severalenemy fighter formations in Central Europe. When the F-15 fire control system "locks on" to a single target and provides attack steering, it may remove other targets from the screen and deny the operator information on other enemy aircraft. A delay in "lock on" until the aircraft is near firing range allows monitoring of the overall situation, but that advantage must be balanced against the increased workload of monitoring the cockpit radar display and mentally calculating the intercept solution. A skilled radar intercept officer in the backseat could provide invaluable assistance during the intercept portion of the attack because he could devote most of his attention to the radar display and free the pilot for visual lookout and operation of the airplane. This expertise would also be useful when a system malfunction or electronic countermeasures degraded the performance of the fire control system. Most veteran air defense pilots agree that the radar intercept officer in the F-101 significantly enhanced the intercept capability of the F-101. A radar intercept officer would enhance the F-15 task of attacking numerically superior formations of maneuverable fighter-type targets.
Consideration of a two-seat aircraft raises the fundamental questions: How much larger would the airplane be, and how much performance would be lost? One can estimate the weight penalties of the second seat by examining previous two-seat conversions of single-seat jet fighters (e.g., TF-86/F-86A, F-100F/ F-100D, F-106B/F-106A). Weight differences vary from the 1000 pounds of the two-gun F-100F versus the four-gun F-100D to 900 pounds for the F-106B, which also carries 500 pounds less fuel than the F-106A while retaining the full fire control system. A weight penalty of 1000 to 1300 pounds is considerably less significant on a modern 30,000-poundjet fighter than on a 9200-pound Mustang or an 18,000-pound F-86 (actually, the two-seat TF-86, since it had no guns weighed less than the F-86A and carried 300 pounds more fuel).17 The present two-seat F-15B weighs only 800 pounds more than the F-15A, and performance figures in flight manuals are identical for the two aircraft. The two-seat F-16B loses 1200 pounds of fuel for installation of the second seat; the F-15B retains all the fuel of the F-15A and loses only the compartment for the tactical electronic warfare support (TEWS), which could be placed elsewhere in the aircraft. One can conclude that the relative performance/weight penalty of the second crew member is less for the contemporary jet fighter than for earlier fighters and that the F-15 would suffer no appreciable loss in performance.
A possible disadvantage of the two-seat fighter is the increased life-cycle cost of the aircraft. If a single backseater in a "unit" of live two-seat F-15s sights an enemy fighter about to attack or identifies an unsafe flight condition and saves his airplane, he would in effect "pay" for the life-cycle cost of converting the entire unit. Marine Corps studies show that the backseater visually sighted most aerial threats in Southeast Asia.18 Navy studies further indicate that the two-seat fighter enjoys a better flight safety record than the singleseater.19 Thus, it seems that the backseater is cost-effective in increased survivability alone.
Another objection to the two-seat fighter that is difficult to assess quantitatively is best described in the words of an F-16 pilot: "Communication from ear-to-ear is much better than from cockpit to cockpit.20 Of course, crew coordination is a factor that cannot be ignored. The Hughes simulator study noted that as threat density increased, the performance of the two-man crew was consistently better than the single-pilot performance. In the maximum threat density, however, the single crew member became more effective. In other words, the two-man crew was superior until their crew coordination broke down because of too many things happening too quickly for successful relay of information. Part of this breakdown occurred because the test called for a deliberately poorly designed two-man cockpit to force extensive intercockpit coordination.21 But the results definitely show the need for crew coordination procedures designed for a high-threat, fast-moving situation to prevent one member of a two-man crew from hindering another member.
Experiences in Southeast Asia demonstrate the effect of proper crew coordination. For example, the U.S. Navy initiated the TOP GUN program in 1969 because it was dissatisfied with its aerial combat performance from 1966 to 1968. This program emphasized coordination between leader and wingman and between pilot and backseater. Fighter crews flew against airplanes similar to enemy aircraft in size and performance and, in the process, learned to function routinely as teams in the fast-moving aerial combat arena. The U.S. Air Force had no such program at the time. (I was a back-seater in an F-4 air defense squadron and can attest to the lack of emphasis on aerial combat maneuvering and the necessary crew coordination.) When the air war over North Vietnam resumed in 1972, the Navys kill ratio jumped from 3.7 to 1 to 13 to 1, but the Air Forces ratio changed very littlefrom 3 to 1 to 2 to 1.22 Although such factors as different patrol area and force ratios prevent any simple quantitative comparisons of Navy and Air Force experience, improvements after TOP GUN were sufficiently dramatic to confirm the value of an aggressive training program. That is, crew coordination necessary to operate effectively in aerial combat can be developed, but it must be developed in training.
A second crew member can enhance the capability of the airplane only if he works as a member of a team. Training programs must focus on procedures that ensure automatic crew coordination in matters other than checklist challenge and response. The Navy experience indicates that the absence of training in the past does not infer an impossible task. One of the pilots who took part in the original design of the F-15 admitted that the poor skill levels of the F-4 pilot/navigator backseaters in 1968 exerted a considerable influence on the single-seat choice. The same officer observed that since that time he had become convinced of the value of the backseater in offensive and defensive combat, once the proper doctrine and training program had finally been developed. In "two-versus-many" exercise engagements, the two-seat F-4 was extremely successful due to the pilots ability to concentrate on the offensive phase as long as possible while the backseater directed the disengagement when it became necessary to "get out of Dodge."
The arguments point in one direction: a well-trained second man in the fighter aircraft can optimize its offensive and defensive potential without significantly degrading its performance. Especially in this decade the added increment of fighter capability could be critical since the Air Force will be fighting out-numbered. Attrition rates in contemporary high-intensity conflicts such as the Yom Kippur War have been significantly higher than World War II rates, and a war in Central Europe could produce astronomical losses.23 In view of the projected total of only 729 F-15s, the Air Force must be sure that it can achieve the maximum possible benefits from its fighters in terms of enemy airplanes destroyed. The human factor in aerial combat is often overlooked in favor of simply evaluating airplanes and armament. Historically, the consistently successful fighter pilot has been a rare breed. Of 40,000 airplanes destroyed by the Luftwaffe on the Eastern Front in World War II, 30,000 were destroyed by only 300 German pilots.24 An average 4 percent of the pilots have accounted for 40 percent of the kills in every war since World War I.25
In a study of successful fighter pilots, the McDonnell-Douglas Corporation developed a list of 45 common traits ranging from mechanical skills to personality traits and decision-making ability.26 Since every fighter pilot cannot be a Hartmann or Bong or Tuck and since the United States has fighter planes that are qualitatively superior but numerically inferior to enemy planes, one can conclude that it makes sense to maximize the efficiency of the average fighter pilot with an optimum crew of two in the cockpit.
The Air Force cannot allow itself to be swayed by the common knowledge of the past regarding the inviolability of the single-seat fighter concept. The improved performance of fighter aircraft and their armament makes todays aerial combat task much more complex and demanding. The unseen attacker must be regarded as a threat, not at a range of 200 yards but at many miles. The F-15 is not an overgrown P-51 Mustang nor will it be engaging Focke-Wulfe FW-190s. Military decision-makers must give serious consideration to converting the F-15s to two-seat aircraft. They should not permit preconceived notions based on outmoded ideas to color their judgment. Design studies that concentrate on performance and avionics capabilities alone and ignore the operator and his workload in actual combat cannot be allowed to dictate future fighter design. Buck Rogerss television spacecraft has a second seat, but it is usually empty. If the villains continue to get more and better ships, perhaps even Hollywood will give in and fill that seat.
Edwards AFB, California
1. Pete Bowers, "Those Incredible Rotary Engines," in Air Trails Military Aircraft (New York, 1979), pp. 24-31; and William E. Barrett, The First War Planes (New York, 1969), pp. 41 and 89.
2. Arch Whitehouse, The Military Airplane (New York, 1971), pp. 116-22; Jack Dean, "Legion of the Lost" on the P-30, Wings Magazine, October 1974, pp. 36-45. Also Profile Publications Nos. 117 and 123 (Surrey, England), The Boulton-Paul Defiant by Michael Boyer and The Messerschmitt Bf 110 by Martin C. Windrow.
3. For a definitive history of the development of night fighters/interceptors and their associated radars, see Bill Gunston, Night Fighters: A Development and Combat History (New York, 1976).
4. Information on development trends came from Marcelle Knaach, The Encyclopedia of USAF Aircraft and Missile Systems, Vol. 1; Post-World War II Fighters 1945-1973 (Washington: Office of Air Force History, 1978).
5. James Perry Stevenson, McDonnell-Douglas F-15 (Fallbrook, California, 1978), pp. 8-15.
6. Leonard Carson, "Clobbering," Wings Magazine, April 1977, p. 48
7. James E. Dornan, Jr., The US War Machine (New York, 1978), pp. 238-39.
8. Stevenson, pp. 75-79.
9. "New Look at NATO Air War," Armed Forces Journal, May 1974, pp. 32-34.
10. Charles Kamps, Jr., "The Next War," in Strategy and Tactics, July-August 1979, pp. 15-35.
11. Bill Sweetman, "Military Aircraft of the World," Flight International, 3 March 1979, p. 363; and "The Price of Power," Time, 29 October 1979, p. 28.
12. Bill Hamilton, "One versus Many," USAF Fighter Weapons Newsletter, Fall 1977, pp. 1-7.
13. Hughes Aircraft Company, Crew Size Evaluation for Tactical All-Weather Strike Aircraft, Technical Report AFAL-TR-76-79 Air Force Avionics Laboratory (Wright-Patterson AFB, Ohio, April 1977). Hereafter referred to as Hughes Report.
14. Ibid., p. 12.
15. Colonel Hubert Zemke, "The Long Reach," as reprinted in TAC Attack, November 1970, pp. 24-27.
16. Major K. P. OMara, "Past Performance and Mission Dictate that the Corps Use a Two-Seat Fighter," Marine Corps Gazette, August 1979, p. 62.
17. Ray Wagner, The North American Sabre (London, 1963), pp. 89-90 and 143-45; Norman Polmar, editor, World Combat Aircraft Directory (New York, 1976), p. 165; Hughes Report, p. 5.
18. OMara, p. 62.
19. Anonymous Navy position paper, 2 May 1973, cited in the Hughes Report, p. 4.
20. "The F-16 in Europe." Airscoop (USAFEP 127-3), August 1979, p. 3.
21. Hughes Report, p. 54.
22. Lou Drendell, . . . And Kill MIGs (Warren, Michigan, 1974), p. 30.
23. "New Look at NATO Air War," pp. 32-34.
24. Technical Sergeant Herman J. Kokojan and Senior Master Sergeant Harold Newcomb, "The Bandits," Airman, March 1978, p. 21.
25. Jack N. Merritt and Pierre M. Sprey, "Quality, Quantity, or Training," USAF Fighter Weapons Review, Summer 1974, p. 13.
26. Edward W. Youngling et al, Feasibility Study to Predict Combat Effectiveness for Selected Military Roles: Fighter Pilot Effectiveness (Saint Louis: McDonnell-Douglas Astronautics Company, 29 April 1977), MDC Report El634, pp. 4-13.
Major Flanagans article was developed from an Air Command and Staff College research report.
Major William A. Flanagan (B.S. University of Virginia; M.S., Air Force Institute of Technology School of Engineering) is Chief of the Flight Test Engineering Branch for the SR-17 at Palmdale, California. With more than 2000 flight hours in the RF-4, F-4, and F-111, he served as a Instructor Weapon System Officer (WSO) in an air defense F-4E squadron in Germany for four years and received the Seventeenth Air Force Top Air Defense WSO Award for 1973. Previous assignments include Tan Son Nhut AB, RVN, Hahn AB Germany, Edwards AFB, California, and Eglin AFB, Florida. Major Flanagan is a Distinguished Graduate of Air Command and Staff College.
The conclusions and opinions expressed in this document are those of the author cultivated in the freedom of expression, academic environment of Air University. They do not reflect the official position of the U.S. Government, Department of Defense, the United States Air Force or the Air University.
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