[Spitfire XIV-E]

The Lockheed P-38 Lightning was a WWII American fighter aircraft. Developed to a United States Army Air Corps requirement, the P-38 had distinctive twin tail booms and a single, central nacelle containing the cockpit and armament. The aircraft was used in a number of different roles, including dive bombing, level bombing, ground strafing, photo reconnaissance, and extensively as a long-range escort fighter when equipped with drop-tanks under its wings. The P-38 was used most extensively and successfully in the Pacific Theatre and the China-Burma-India Theatre, where it was flown by American pilots with the highest number of aerial victories to this date. America's top ace Richard Bong earned 40 victories (in a Lightning he called Marge), and Thomas McGuire scored 38. In the South West Pacific Theatre, it was a primary fighter of the USAAF until the appearance of large numbers of P-51D Mustangs toward the end of the war.

The P-38 was the only American fighter aircraft in active production throughout the duration of American involvement in the war, from Pearl Harbor to VJ Day.




Lockheed P-38J Lightning. The definitive version built.


Design and Development

Lockheed designed the P-38 in response to the 1937 USAAC Circular Proposal X-608 request for a high-altitude interceptor aircraft having "the tactical mission of interception and attack of hostile aircraft at high-altitude". Specifications called for a maximum airspeed of at least 360 miles per hour at altitude, a climb to 20,000 feet within 6 minutes; the toughest set of specifications the USAAC had presented to that date. The Bell P-39 Airacobra and the Curtiss P-40 Warhawk were designed to the same requirement, as was the unbuilt Vultee XP1015.

The Lockheed design team, under the direction of Hall Hibbard and the legendary Clarence "Kelly" Johnson, considered a range of configurations. All options considered by Lockheed were twin-engined, as it was judged that no single available engine was powerful enough to be able to meet the USAAC's requirements. (Engine development in WWII subsequently saw an approximate doubling of fighter engine horsepower, allowing many later single engine designs to achieve 400 mph +).

The eventual design was somewhat unique in comparison to existing fighter aircraft. The Lockheed team chose twin booms to accomodate the tail assembly, engines and turbo superchargers, with a central nacelle for the pilot and armament. The nose was designed to carry 2 Browning .50 calibre machine guns with 200 rounds per gun, 2 .30 calibre Brownings with 500 rounds per gun, and an Oldsmobile 37mm Cannon with 15 rounds. Clustering all the armament in the nose was unlike most other US aircraft, which used wing mounted guns where the trajectories were set up to criss-cross at one or more ponts in a "convergence zone". The nose-mounted guns did not suffer from having their useful ranges limited by pattern convergance, meaning good pilots could shoot much farther. A Lightning could reliably hit targets at any range up to 1,000 yards, where as other fighters had to pick a single convergance range between 100 and 250 yards. The clustered weapons had a "Buzz Saw" effect on the receiving end, making the aircraft effective for strafing as well.

The Lockheed design incorporated tricycle undercarriage and a bubble canopy, and featured 2 1,000 hp turbo-supercharged 12 cylinder Allison V-1710 engines fitted with counter-rotating propellers to eliminate the effect of engine torque, with the superchargers positioned behind the engines in the booms. It was the first American fighter to make extensive use of stainless steel and smooth, flush riveted butt-jointed aluminium skin panels. It was the first fighter faster than 400 mph.

Lockheed won the competition on 23rd June 1937 with its Model 22, and was contracted to build a prototype XP-38 for $163,000, though Lockheed's own costs on the prototype would add up to $761,000. Construction began in July 1938 and the XP-38 first flew on 27th January 1939. The 11th February 1939 flight to relocate the aircraft for testing at Wright Field was extended by General Henry "Hap" Arnold, commander of the USAAC, to demonstrate the performance of the aircraft. It set a cross-continent speed record by flying from California to New York in 7 hours and 2 minutes, but landed short of the Mitchel Field runway in Hempstead, New York, and was wrecked. However, on the basis of the record flight, the Air Corps ordered 13 YP-38's on 27th April 1939 for $134,284 apiece. (The initial Y in YP was the USAAC's designation for a prototype while the X in XP was for experimental).

Manufacture of the YP-38's fell behind schedule, at least partly due to the need for mass-production suitability making them substantially different in construction than the prototype. Another factor was the sudden required facility expansion of Lockheed in Burbank, taking it from a specialised civilian firm dealing with small orders to becoming a large government defense contractor making Venturas, Harpoons, Lodestars, Hudsons, and designing the Constellation airliner for TWA. The first YP-38 was not completed until september 1940, with its maiden flight on 17th September. The 13th and final YP-38 was delivered to the Air Corps in June 1941; 12 aircraft were retained for flight testing and one for destructive stress testing. The YP's were subsequently redesigned and differed greatly in detail from the hand-built XP-38. They were lighter, included changes in engine fit, and the propeller rotation was reversed, with blades rotating outwards (away) from the cockpit at the top of the arc rather than inwards as before. This improved the aircraft's stability as a gunnery platform.

Test flights revealed problems initially believed to be tail flutter. During high-speed flight approaching Mach 0.68, especially during dives, the aircraft's tail would begin to shake violently and the nose would tuck under, steepening the dive. Once caught in this dive, the fighter would enter a high-speed compressibilty stall and the controls would lock up, leaving the pilot no option but to bail out (if possible) or remain with the aircraft until it got down to denser air where he might have a chance to pull out. During a test flight in May 1941, USAAC Major Signa Gilkey managed to stay with a YP-38 in a compressibility lockup, riding it out until he recovered gradually using elevator trim. Lockheed engineers were very concerned at this limitation, but first they had to concentrate on filling the current order of aircraft, 65 Lightnings were finished by September 1941, with more on the way.

By November 1941, many of the initial assembly line challenges had been met and there was some breathing room for the engineering team to tackle the problem of frozen controls in a dive. Lockheed had a few ideas for tests that would help them find an answer. The first solution tried was the fitting of spring-loaded servo tabs on the elevator trailing edge; tabs that were designed to aid the pilot when control yoke forces rose over 30 pounds, as would be expected in a high-speed dive. At that point, the tabs would begin to multiply the effort of the pliot's actions. The expert test pilot, 43 year old Ralph Virden, was given a specific high-altitiude test sequence to follow and was told to restrict his speed and fast maneuvering in denser air at low altitudes since the new mechanism could exert tremendous leverage under those conditions. A note was taped to the instrument panel of the prototype underscoring this instruction. On 4th November 1941, Virden climbed into a YP-38 and completed the test sequence successfully, but 15 minutes later was seen in a steep dive followed by a high-G pullout. The tail unit of the aircraft failed at about 3,000 feet during the high speed dive recovery; Virden was killed in the subsequent crash. The Lockheed design office was justifiably upset, but their design engineers could only conclude that servo tabs were not the solution for loss of control in a dive. Lockheed still had to find the problem; the Army Air Corps was sure it was flutter, ordering Lockheed to look more closely at the tail.

Although the P-38's empennage was completely skinned in aluminium (not fabric) and was quite rigid, in 1941, flutter was a familiar engineering problem related to a too flexible tail. At no time did the P-38 suffer from true flutter. To prove a point, one elevator and it's vertical stabilisers were skinned with metal 63% thicker than standard-the increase in rigidity made no difference to vibration. Army Lt. Colonel Kenneth B. Wolfe (head of Army Production Engineering) asked Lockheed to try external mass balances above and below the elevator, though the P-38 already had large mass balances elegantly placed within each vertical stabiliser. Various configurations of external mass balances were equipped and dangerously steep test flights flown to document their perfomance. Explaining to Wolfe's report No. 2414, Kelly Johnson wrote " ... the violence of the vibration was unchanged and the diving tendency was naturally the same for all conditions". The external mass balances did not help at all. None the less, at Wolfe's insistence, the additional mass balances were a feature of every P-38 built from then on.

After months of pushing NACA to provide Mach 0.75 wind tunnel speeds (and finally succeeding), the compressibility problem was revealed to be the centre of lift moving back towards the tail when in high-speed airflow. The compressibility problem was solved by changing the geometry of the wing's underside when diving so as to keep lift within bounds of the top of the wing. In February 1943, quick-acting dive flaps were tried and proven by Lockheed test pilots. The dive flaps were were installed outboard of the engine nacelles and in action they extended downwards 35 degrees in 1 1/2 seconds. The flaps did not act as a speed break, they affected the centre of pressure distribution so that the wing would not lose lift. Late in 1943, a few hundred dive flap field modification kits were assembled to give North African, European and Pacific based P-38's a chance to withstand compressibilty and expand their combat tactics. Unfortunately, these crucial flaps did not always reach their destination. In March 1944, 200 field dive flap kits intended for European Theatre P-38J's were destroyed in a mistaken identification incident in which an RAF fighter shot down the Douglas C-54 Skymaster bringing the shipment to England. Back in Burbank, P-38J's coming off the assembly line in Spring 1944 were towed out to the tarmac and modified in the open air. The flaps were finally incorporated in to the production line in June 1944 on the last 210 P-38J's. The delay in bringing the dive flap and its freedom of tactical maneuver to the fighting pilot was far too lengthy. Of all Lightnings built, only the final 50% would have the dive flaps installed on the assembly line.

Johnson later recalled - "I broke an ulcer over compressibility on the P-38 because we flew in to the speed range where no one had been before, and we had difficulty convincing people that it wasn't the funny looking airplane itself, but a fundamental physical problem. We found out what happened when the Lightning shed its tail and we worked during the whole war to get 15 more knots of speed out of the P-38. We saw compressibility as a brick wall for a long time. Then we learned how to get through it".

Buffeting was another early aerodynamic problem, difficult to sort out from compressibility as both were reported by test pilots as "tail shake". Buffeting came about from airflow disturbances ahead of the tail; the airplane would shake at high speed. Leading edge wing slots were triedas were combinations of filleting between the wing, cockpit and engine nacelles. Air tunnel test no. 15 solved the buffeting problem completely and its fillet solution was fitted to every subsequent P-38 airframe. Fillet kits were sent out to every squadron flying Lightnings. The problem was traced to a 40% increase in air speed at the wing-fuselage junction where the chord/thickness ratio was highest. An air speed of 500 mph at 25,000 feet could push airflow at the wing-fusealge junction close to the speed of sound. Filleting forever solved the buffeting problem for the P-38E and later models.

Another issue with the P-38 arose from its unique design feature of outwardly rotating counter-rotating propellers. Losing one of the two engines in any twin engine non centreline thrust aircraft on takeoff creates sudden drag, yawing the nose toward the dead engine and rolling the wingtip down on the side of the dead engine. Normal training in flying twin-engine aircraft when losing an engine on takeoff would be to push the remaining engine to full throttle; if a pilot did that in a P-38, regardless of which engine had failed, the resulting engine torque and p-factor force produced a sudden uncrontollable yawing roll and the aircraft would flip over and slam to the ground. Eventually, procedures were taught to allow to allow the pilot to deal with the situation by reducing power on the running engine, feathering the prop on the dead engine, and then increasing power gradually until the aircraft was stable in flight. Single-engine takeoffs were possible, but not with a maximum combat load.

The British and French had placed orders for the P-38 totalling 667 aircraft. They would be a version of the P-38E (Model 322F/322B), without turbo-supercharging (due to US government export prohibition), and twin right handed engines instead of counter-rotating, for commonality with the large numbers of Curtiss P-40 Tomahawks both nations had on order. After the fall of France in June 1940, the British took over the entire order and re-christened the aircraft Lightning I. 3 were delivered in March 1942 and, after discovering, without superchargers, at low altitude and when using lower-octane British aircraft fuel, they had a maximum speed of 300 mph and poor handling characteristics, the entire order was canceled. The 140 remaining Lightning I's were completed as USAAF machines with couter-rotating engines but still minus superchargers. Most were relegated to USAAF training units under the designation RP-322. These aircraft helped the USAAF train new pilots to fly a powerful and complex new fighter. A few model 322 aircraft were used as test modification platforms such as for smoke laying canisters and dual air-dropped torpedoes. The RP-322 was a fairly fast aircraft (some of the fastest post-war racing P-38's were virtually identical in layout to the P-322 II) at low altitude and well suited to a trainer. The other positive result of the failed British/French order was to give the aircraft its name. Lockheed had originally dubbed the aircraft Atalanta in the company tradition of naming aircraft after mythological and celestial figures, but the RAF name won out.


Operational History

The first unit to receive P-38's was the 1st Fighter Group. After the attack on Pearl Harbor, the unit joined the 14th Pursuit Group in San Diego to provide West Coast defense.

Entry to the war

The first Lightning to see active service was the F-4 version, a P-38E in which the guns were replaced by 4 cameras. They joined the 8th Photographic Squadron out of Australia on 4th April 1942. These F-4's were operated by the Royal Australian Air Force in this theatre for a short period in September 1942.

On 29th May 1942, 25 P-38's began operating in the Aleutian Islands off Alaska. The fighter's long-range made it well suited to the campaign over the almost 1,200 mile long island chain, and it would be flown there for the rest of the war. The Aleutians were one of the most rugged environments available for testing the new aircraft under combat conditions. More Lightnings were lost due to severe weather and other conditions than enemy action, and there were cases where Lightning pilots, mesmerized by flying for hours over grey seas under grey skies, simply flew in to the water. On 9th August 1942, 2 P-38E's of the 343rd Fighter Group, 11th Airforce, at the end of a 1,000 mile long range patrol, happened upon a pair of Japanese Kawanishi H6K "Mavis" flying boats and destroyed them, making them the first Japanese aircraft to be shot down by Lightnings.

European Theatre

After the Battle of Midway, the USAAF began redeploying fighter groups to Britain as part of Operation Bolero, and Lightnings of the 1st Fighter Group were flown across the Atlantic via Iceland. On 14th August 1942, a P38F and a P-40 operating out of Iceland shot down a Focke-Wulf Fw 200 Condor over the Atlantic. This was the first Luftwaffe aircraft destroyed by the USAAF.

P-38's had a number of lucky escapes, exemplified by the arrival of the 71st Fighter Squadron at Goxhill (Lincolnshire, England) in July 1942. The official handover ceremony ws scheduled for mid-August, but on the day before the ceremony, Goxhill experienced its only air raid of the war. A single German bomber flew overhead and dropped a very well aimed bomb right on the intersection between the 2 newly concreted runways, but it didn't explode and the aircraft were able to continue their mission. (As it turned out, the bomb could not be removed and, for the duration of the war, aircraft had to pass over it every time they took off).

After 347 sorties with no enemy contact, the 1st, 14th and 82nd Fighter Groups were transferred to the 12th Airforce in North Africa as part of the force being built up for Operation Torch. On 19th November 1942, Lightnings escorted B-17's on a raid over Tunis. On 5th April 1943, 26 P-38F's of the 82nd destroyed 31 enemy aircraft, helping to establish air superiority in the area, and earning it the German nickname - "der Gabelschwanz-Teufel" - the Fork Tailed devil. The P-38 remained active in the Mediterranean for the rest of the war. It was in this Theatre that the P-38 suffered its heaviest losses in the air. On 25th August 1943, 13 P-38's were shot down ina single sortie by JG 53 Bf 109's without achieving a single kill. On 2nd September 1943, 10 P-38's were shot down, in return for a single kill, the 67-victory ace Franz Schiess (who was the leading "Lightning" killer in the Luftwaffe with 17 destroyed).

Experiences over Germany had shown the need for long-range escort fighters to protect the 8th Air Force's heavy bombers. The P-38H's of the 55th Fighter Group were transferred to the 8th in England in September 1943, and were joined by the 20th, 364th and 479th Fighter Groups soon after.

In the Mediterranean Theatre, Italian pilots started to face P-38's from late 1942 and considered the type a formidable foe even compared to other lethal fighters including the Supermarine Spitfire. A small number of P-38's fell in to the hands of German and Italian units and were subsequently tested and used in combat. Col. Tondi used used a P-38, possibly an "E" model, that landed in Sardinia due to a navigational error. Tondi claimed at least 1 B-24, downed on 11th August 1943. The P-38 was eventually acquired by Italy for postwar service.

The P-38 performed well in the European Theatre, but suffered frequent engine failures, due to the inadequate cooling system. Many of the aircraft's problems were addressed by the P-38J, but by September 1944, all but one of the Lightning groups in the 8th Airforce had converted to the P-51. The 8th did continue to operate the F-5 reconnaissance version with more success.

Pacific Theatre

The P-38 was used most extensively and successfully in the Pacific Theatre, where it proved ideally suited, combining excellent performance with very long range. The P-38 was used in a variety of roles, especially escorting bombers at altitiudes between 18,000 and 25,000 feet. The P-38 was credited with destroying more Japanese aircraft than any other USAAF fighter. Freezing cockpits were not a problem at low altitude in the tropics. In fact, since there was no way to open a window in flight as it caused buffeting by setting up turbulence through the tailplane, it was often too hot; pilots taking low altitude assignments would often fly stripped down to shorts, tennis shoes, and parachute. Wile the P-38 could not out-maneuver the A6M Zero and most other Japanese fighters, its speed and rate of climb gave American pilots the option of choosing to fight or run, and its focused fire power was even more deadly to lightly-armoured Japanese warplanes than to the Germans'. The concentrated, parallel stream of bullets allowed aerial victory at much longer distances than fighters with wing-mounted guns. It is therefore ironic that Dick Bong, the United States' highest scoring WWII air ace (40 victories solely in P-38's), would fly directly at his targets to make sure he hit them (as he himself acknowledged his poor shooting ability), in some cases flying through the debris of his victim (and on one occasion colliding with an enemy aircraft which was claimed as a "probable" victory). The twin Allison engines performed admirably in the pacific.

The Yamamoto ambush

The Lightning featured in one of the most significant operations of the Pacific Theatre, the interception, on 18th April 1943, of Admiral Isoroku Yamamoto, the architect of Japan's naval strategy in the Pacific including the attack on Pearl Harbor. When American code breakers found out that he was flying to Bougainville Island to conduct a front-line inspection, 16 P-38G Lightnings were sent on a long-range fighter-intercept mission, flying 435 miles from Guadalcanal at heights of 10 to 50 feet above the ocean to avoid detection. The Lightnings met Yamamoto's 2 Mitsubishi G4M "Betty" fast bomber transports and 6 escorting Zeros just as they arrived. The first Betty crashed in the jungle and the second ditched near the coast. 2 Zeros were also claimed by the American fighters with the loss of 1 P-38. Japanese searchers found Yamamoto's body at the jungle crash site the next day.

An aircraft of many roles

Over 10,000 Lightnings were produced in all; becoming the only US combat aircraft to remain in continuous production throughout America's involvement in WWII.

The Lightning was adapted for other roles. Including Night Fighter and Pathfinder. 75 P-38L's were converted to P-38M "Night Lightning" configuration, painted black with conical flash hiders on the guns, an AN/APS-6 radar pod below the nose, and a second cockpit with a raised canopy behind the pilot's canopy for a radar operator. The headroom in the rear cockpit was limited, requiring radar operators who were preferably short in stature.





Left to Right - YP-38 Prototype, Major Dick Bong in the cockpit of his P-38 "Marge", An F-5A Photo-Reconnaissance Lightning.



Left to Right - P-38 production line at Burbank near Los Angeles, P-38 Cockpit view, P-38M "Night Lightning"