Aircraft Survivability – The Korean War
By: David Legg
F4U-4 Corsairs and AD Skyraiders Off the North Korean Coast, August 1951 (U.S. Navy Photo) “North Korea’s President Kim Il Sung launched his ground forces south of the 38th parallel at 0400 hours on June 25, 1950. Eleven hours later, two propeller-driven North Korean Yak-9P fighters appeared over Seoul International Airport and strafed seven Republic of Korea aircraft. At nearby Kimpo, two more Yaks shot up the control tower, blew up a fuel tank, then set an American C-54 transport on fire” .
A MIX OF THE OLD AND NEW
The onslaught of troops and armor of the Democratic People’s Republic of Korea (i.e., North Korea) into the Republic of Korea (ROK) (i.e., South Korea) caught U.S. and Allied air forces in the middle of transitioning, at least in part, from World War II-era piston-engine to jet-powered aircraft. The U.S. Air Force (USAF) was equipped with a mix of piston-engine aircraft (e.g., the B-29 Super Fortress heavy bomber, the B-26B/C Invader medium bomber, the F-51D Mustang fighter/bomber, and the F-82G Twin Mustang) as well as jet-powered aircraft (e.g., the F-80C Shooting Star fighter/bomber, the F-84 Thunderjet fighter/bomber, and the F-86 Sabre fighter). The F-86 would be the only swept-wing, jet-powered aircraft to see combat with the USAF, U.S. Navy (USN), or United Nation (U.N.) air forces during the Korean War.
The USN and U.S. Marine Corps (USMC) also included a mix of piston-engine aircraft (e.g., the F4U-4/4B/5N Corsair fighter/bomber [such as the one shown in Figure 1], the AD Skyraider attack aircraft, and the F7F-3N Tigercat night fighter) and jet-powered aircraft (e.g., the F9F-2/5 Panther fighter/bomber, the F2H Banshee fighter/bomber, and the F3D-2 Skyknight night fighter).
The Royal Navy’s Fleet Air Arm (FAA) and Royal Australian Navy (RAN) were equipped with piston-engine aircraft. These included improved versions of the World War II-era Supermarine Seafire fighter/bomber and the Fairey Firefly attack aircraft as well as the immediate post-World War II Hawker Sea Fury fighter/bomber . In addition, the South African Air Force (SAAF), ROK Air Force (ROKAF), and Royal Australian Air Force (RAAF) were equipped with the P-51D Mustang.
On the other side of the conflict, the North Korean Air Force (NKAF) was equipped with a variety of World War II-era Soviet piston-engine-powered aircraft, including the heavily armored IL-2 and IL-10 Sturmovik ground attack aircraft, the YAK-7 fighter, the YAK-9 fighter, the LA-7 fighter, the LA-11 fighter, and the PO-2 biplane trainer/light attack aircraft .
The Allied air forces had little problem in dealing with the NKAF. However, this situation started to change when, in November of 1950, Russian-piloted MiG-15 swept-wing jets were first encountered over Korea. At the time, the Russians did not acknowledge that their pilots were flying over North Korea. And it has taken more than 50 years for the full story of their involvement to become known. Like their U.S. and U.N. counterparts, many of these pilots were veterans of World War II [1, 3, 4].
The MiG-15, which was primarily designed as a bomber interceptor, included armor protection for the pilot, a bullet-resistant windscreen, self-sealing fuel tanks, a rugged structural design, and heavy armament, including two 23-mm and one 37-mm cannon. The MiG-15 was superior in performance to all Allied fighter aircraft with the exception of the F-86 Sabre. In addition, the MiG-15 had the advantage of a more lethal cannon armament compared to the F-86, F-84, and F-80C .50-caliber machine gun armament. Russian MiG-15 Korean War ace Col. Yevgeniy Pepelyayev stated, “The American .50-caliber machine guns acted on our aircraft like peas. It was routine for our aircraft to return home with 40 or 50 hits” . In contrast, some USAF bomber crews dubbed MiG-15 (cannon) fire “horizontal flak” .
THE SURFACE-TO-AIR THREAT
Facing the Allied air forces was the anti-aircraft artillery (AAA) threat posed by the North Korean forces. This threat included various small arms; 12.7-mm machine guns; the single or dual-mount M1941 25-mm cannon (with an effective ceiling of 4,000 ft and a rate-of-fire of 240–250 rounds/minute); the M1939 37-mm cannon (with an effective service ceiling of 4,500 ft and a rate-of-fire of 160–180 rounds/minute); and the M1938 75-mm and M1939 85-mm cannons (each with an effective ceiling of 25,000 ft and a rate-of-fire of 15–20 rounds/minute) . The 75-mm and 85-mm cannon were of particular concern to the B-29 crews once these guns were coupled with radar and proximity-fuze shells . Figure 2 shows a RAN Firefly damaged by flak.
The North Korean air defenses also included a variety of radars, including the U.S. SCR-584; the World War II-era German Wurzburg; and other radars of U.S., British, and Russian design . In contrast to this sophisticated threat, North Koreans also strung cables across the many narrow valleys . These cables, much like those deployed by the British in the defense of London during World War I, were designed to inflict structural damage to any aircraft upon impact.
The majority of combat aircraft seeing action, with the exception of the PO-2 biplane, incorporated the “standard” World War II-era vulnerability reduction features. These features included items such as cockpit armor, bullet-resistant forward windscreen glass, self-sealing fuel tanks, and general rugged design (see Figures 3 and 4). Of the various Allied fighter bomber aircraft, the F4U-4/4B, AD, and Sea Fury were each powered by an air-cooled radial engine while the F-51D, Seafire, and Firefly were each powered with the more vulnerable liquid-cooled engine. Although many World War II Russian aircraft designs were equipped with engine-exhaust-based dry-bay fire protection systems, it is not known if the North Korean aircraft were operational with the system. (Of note here is that, near the end of World War II, the U.S. Army had developed and tested effective CO2-based dry-bay fire suppression system prototypes for the B-17, B-29, and other aircraft. However, these systems were never productionized for installation.)
Not surprisingly, these existing vulnerability reduction features were found to be lacking for aircraft performing the close air support role and would thus be improved upon for several aircraft.
RELIVING THE HARD LEARNED LESSONS OF WORLD WAR II
When the North Korean invasion occurred, the air response was primarily met by the USAF with F-51D and F-80C aircraft flying fighter and fighter/ bomber missions in support of the retreating ROK and U.S. Army troops.
Operating from Japan severely impacted the loitering and offensive payload capability of the jet-powered F-80C. In an attempt to solve this issue, an additional 145 F-51D aircraft from U.S.-based USAF Air National Guard (ANG) units were transported by the USS Boxer (CV-21) to Japan .
While critical and effective in blunting the North Korean advance, the use of the F-51D Mustang in the close air support role would result in reliving the hard learned lessons of World War II. As recorded by the 8th Fighter-Bomber Group historian, “A lot of pilots had seen vivid demonstrations of why the F-51 was not a good-ground support fighter in the last war, and weren’t exactly intrigued by the thought of playing guinea pig to prove the same thing over again” [6, 8]. The reason for this lack of enthusiasm was the vulnerability of the F-51D’s liquid-cooled engine, coolant lines, and radiator. Col. Bill Myers, a veteran World War II P-47 pilot, is quoted as saying that every time he took off on a mission in Korea in his F-51D, he would pray, “Please, God, make this a Thunderbolt” .
The F-51D suffered the highest combat losses of any USAF warplane during the Korean War, with 172 F-51s shot down by enemy ground fire and a total of 164 Mustang pilots either killed or declared missing during ground-attack operations . Likewise, the South African Air Force lost 74 F-51D aircraft out of the total 95, with 12 pilots killed in action and 30 missing in action .
As early as 1942, the vulnerability of the P-51 Mustang’s liquid cooling system was recognized by the U.S. Army Air Forces (USAAF) Proving Ground Command – Eglin Field, which produced a recommendation to provide armor protection to the radiator . However, this recommendation was never acted upon during World War II or Korea, even as losses mounted in the Mustang’s role as a close air support aircraft.
Even the air-cooled radial engine F4U-4/4B Corsair and AD Skyraider experienced heavy losses due to enemy action in Korea. Nearly all of these losses were the result of anti-aircraft fire . The Corsair’s key vulnerability was attributed to the exposed location of its oil cooling system in either wing. As a result of the F4U-4/4B combat losses, a specialized ground attack version was developed for the USMC. The Marines’ AU-1 version included the relocation of the vulnerable air coolers from the wings to the fuselage and the addition of armor to the lower fuselage.
In late 1951, an expedited effort was undertaken to up-armor the AD Skyraider. This effort resulted in the addition of .5-inch aluminum armor plate to the bottom fuselage from the nose to the rear of the cockpit, wing stubs, and sides of the cockpit. The armor weighed 618 lbs, which was in addition to the existing 200 lbs of armor. From its combat debut in the spring of 1952 until May 1953, the armor was credited with saving at least 18 aircraft .
During World War II, the German Luftwaffe’s introduction of the Me-262 was too late to have a significant impact on the USAAF’s bombing campaign against Germany. However, its introduction did provide a glimpse into the future. The Russian’s introduction of MiG-15 did have a significant impact on the B-29 bombing campaign in Korea. As a result of B-29 losses sustained in a series of 1951 bombing raids, B-29 daylight missions in MiG-15 operational areas were abandoned. In fact, during one raid, 44 MiG-15s attacked a formation of 21 B-29s and an estimated 200 escorting F-86 and F-84 fighter aircraft, with the Russian pilots claiming 12 B-29 victories . According to one author :
The B-29s bombing operations shifted to nighttime raids. Switching to nighttime raids worked until the enemy countered by using a system of ground radar sites to guide MiGs to within visual range of the bombers. After three B-29s were shot down on June 10, 1952, by a dedicated night-fighting team of MiGs, raids were suspended until jet night fighter escorts became available.
These escorts would soon arrive in the form of USMC F3D Skyknight and USAF F-94 Starfire night fighters.
Like their early World War II counterparts, heavy bomber designs from a previous decade were not capable of sustained daylight operations in the face of fighter aircraft. In this case, the situation was even more dire, as they could not even survive when escorted.
While perhaps not as intense as the World War II electronic countermeasure (ECM) battle over Germany, a similar battle occurred over the skies of North Korea. USAF RB-50 and specially configured USN AD Skyraider ECM aircraft were used to identify the locations of the North Korean radars. By the end of 1952, 60–70 radars had been located.
In 1952, AD Skyraider aircraft began escorting USN strike packages and dropping chaff to disrupt both radar-directed AAA guns and searchlights. On 16 June 1952, one strike by Task Force 77 AD Skyraiders delivered chaff, which caused a gun-aiming error “as much as one mile in deflection and several thousand feet of in altitude” . Several months later, the USAF would follow suite with modified B-29 bombers doing the same for B-29 night raids.
THE GRUMMAN “IRON WORKS” F9F PANTHER
The F9F Panther was one in a long line of famous Grumman Iron Works aircraft to see combat with the USN. (The name “Iron Works” came from the ruggedness of the aircraft designs.) Due to the design challenges of operating from an aircraft carrier, the F9F-2 incorporated a straight-wing design to assist in slow-speed approaches and catapult launches. On paper, the F9F-2 was not equal in performance to the MiG-15. The F9F-2 did include a relatively heavy armament of four 20-mm cannon.
Although the first U.S. jet-vs.-jet kill had been attributed by the USAF to Air Force 1st Lt. Russell Brown flying an F-80C vs. a MiG-15 on 8 November 1950, Russian historians Leonid Krylov and Yuriy Tepsurkayev credit the first U.S. jet-vs.-jet kill to Navy LCDR William Amen on 9 November 1950. LCDR Amen and his F9F-2 were part of an escort package supporting a strike of AD Skyraiders and F4U-4B Corsairs. When the formation was attacked by 13 MiG-15s, LCDR Amen engaged the MiGs and was credited with a victory over Russian Lt. Grachev. Russian records confirm this victory [1, 3].
In an effort to increase performance, the F9F-5 Panther incorporated a more powerful engine. This improvement was put to the test by two Navy F9F-5 pilots in an engagement that remained classified for many decades . On 18 November 1952, LT Royce Williams, his wingman, LTJG David Rowlands, and two other pilots were flying a Combat Air Patrol (CAP) mission over Task Force 77, which was steaming off the coast of North Korea and within 100 miles of the Russian port of Vladivostok. After two pilots headed back to the carrier USS Oriskany (CVA-34) because of mechanical issues with one of the F9F-5s, the Oriskany warned the flight of incoming aircraft from Russia. These aircraft were MiG-15s headed, with unknown intentions, toward the carrier .
The MiG-15s attacked with an advantage in altitude; and for the next 20 min, a twisting, climbing, and diving dogfight ensued. Both F9F-5s were hit by multiple cannon shells, but both aircraft returned safely to the Oriskany. Upon inspection, it was determined that LT William’s aircraft (shown in Figure 5) had 263 holes created by 20-mm and 37-mm round fragments. One 37-mm round went through the engine. The aircraft was so badly damaged that it was pushed overboard. However, it was a testament to the Grumman Iron Works designers and the rugged construction of the Panther that these aircraft even returned at all.
It should be noted here that the dogfight was not all one-sided. LT Williams was credited with one MiG-15 kill; LTJG Rowlands was credited with a damaged MiG-15; and LTJG John Middleton, who joined the dogfight later, was credited with one MiG-15 kill. All of those involved in the encounter were subjected to an intense debrief and told never to speak of the matter. LT Williams kept that secret for 50 years .
But as incredible as the story sounds, it gets even better. Following the end of the Cold War, the Russians revealed that LT Williams had shot down not one MiG-15, but four! As it turned out, Capt. Belyakov, Capt. Vandalov, Lt. Pakhomkin, and Lt. Tarshinov were all shot down by LT Williams during that 20-min dogfight. No other U.S. pilot would ever shoot down four MiG-15 fighters during a single combat action .
In the end, many USN and USMC pilots who flew the F9F Panther in the Korean skies would owe their lives to the F9F’s rugged construction. These pilots would include USMC Maj. John Glenn, who would later become the first American to orbit the earth; USMC Reserve Capt. Ted Williams, one of the great baseball players of the 1940s and ‘50s; and Navy ENS Neil Armstrong, who would become the first human to set foot on the moon.
Maj. Glenn and his F9F-2 safely returned to base after his aircraft had taken AAA hits in the vertical tail and wind screen (see Figures 6 and 7). Capt. Williams’s aircraft was hit by AAA on three occasions. Once, the aircraft caught fire and lost hydraulics. His flight leader, Maj. Glenn, suggested that he climb to put out the fire. It worked, and Capt. Williams belly-landed his aircraft on a USAF airfield. The aircraft erupted into fire, and Capt. Williams jumped out and ran to safety . ENS Armstrong’s’ F9F-2 was hit by AAA and then flew into an anti-aircraft cable, which removed a large section of the wing. He managed to keep his F9F airborne, however, and once over friendly territory, he ejected near a USMC airfield and was rescued .
LESSONS TO BE RELEARNED . . . AGAIN!
Immediately following the Korean War, the emphasis for airpower was again placed on the delivery of nuclear weapons. Series of U.S., British, French, and Russian jet-powered aircraft were developed as supersonic air interceptors, supersonic nuclear strike aircraft, and long-range nuclear bombers. The last true close air support aircraft to soldier on was the piston-engine AD Skyraider, which would see service with the USN and USAF in the upcoming Vietnam War. Jet aircraft would soon give up their armor, as well as other survivability features, in an never-ending quest for speed. The USAF and USN would pay dearly for this decision, however, in terms of lives and aircraft lost during the long conflict that would soon begin in Southeast Asia.
ABOUT THE AUTHOR
Mr. David Legg is currently the Fixed-Wing Aircraft Branch Head of the Naval Air Warfare Center – Aircraft Division. With 34 years of experience in the aircraft survivability discipline, he has also served as the Survivability Team Lead for many USN aircraft and weapons programs, and he assisted in the rapid development and implementation of tactical paint schemes for in-theater USMC helicopters during Operation Desert Shield and Operation Desert Storm. Mr. Legg was named a U.S. Navy Naval Air Systems Command (NAVAIR) Associate Fellow in 2011, and he holds bachelor’s degrees in mathematics and mechanical engineering from Saint Vincent College and the University of Pittsburgh, respectively.
 Wetterhahn, R. “The Russians of MiG Alley.” The Retired Officer, March 2000.  Cull, B., and D. Newton. With the Yanks in Korea (Volume One). Grub Street, 2000.  Krylov, L., and Y. Tepsurkaev, Y. Soviet MiG-15 Aces of the Korean War. Osprey Publishing Ltd., 2008.  Cleaver, T. M. “Four Down! The Korean Combat the U.S. Tried to Forget.” Flightjournal. com, https://www.flightjournal.com/ four-down/, 2013.  Bruning, J. R. Crimson Sky – The Air Battle for Korea. The History of War Series, Potomac Books, Brassey’s, 1999.  Futrell, R. F. The United States Air Force in Korea: 1950–1953. Office of Air Force History, Washington, DC, 1983.  Thompson, W. F-51 Mustang Units of the Korean War. Osprey Publishing, 2015.  Rowland, M. D. “Why the U.S. Air Force Did Not Use the F-47 Thunderbolt in the Korean War.” Air Power History, vol. 50, no. 3, fall 2003.  Moore, D. M. “The South African Air Force in Korea: An Assessment.” SAAF Museum website, https://saafmuseum.org.za/ korean-war-exhibition/, June 2015.  Army Air Forces Proving Ground Command. “Final Report on Tactical Suitability of the P-51 Type Airplane.” Eglin Field, FL, http://www.wwiiaircraftperformance.org/mustang/p-51-tactical-trials.html, 30 December 1942.  Defense POW/Missing Personnel Office. Korean War Air Loss Database (KORWALD). http://www.dpaa.mil/portals/85/Documents/ KoreaAccounting/korwald_all.pdf, accessed 2018.  DeVine, C. Naval Aviation News. https:// www.history.navy.mil/content/dam/nhhc/ research/histories/naval-aviation/Naval%20 Aviation%20News/1950/pdf/may53.pdf, May 1953.  Bernier, R. “The Deadliest Night Fighter in Korea: Why Douglas Skyknight Crews Weren’t Afraid of the Dark.” Air & Space Magazine, https://www.airspacemag.com/ military-aviation/deadliest-night-fighter-korea-180951418/, July 2014.  Brown, Lt. Col. R. J. “Remembering Ted Williams: A Marine Fighter Pilot.” Leatherneck Magazine, https://www. mca-marines.org/leatherneck/remembering-ted-williams-marine-fighter-pilot, October 2002.  Barbree, J. “A Wing and a Prayer.” Aviation History Magazine, http://www. historynet.com/a-wing-and-a-prayer.htm, July 2017.