Twin Engine Fighter Planes of World War II

P-38, Mosquito, Bf 110, Ki-45-KAI and Whirlwind

By Chuck Hawks

This article is about daylight fighters and interceptors. Leaving aside the jet fighters that appeared at the end of the war (the German Me 262 and British Meteor, for example), there were few successful twin-engine day fighters produced by the major combatants during WW II. There were many attempts to harness the power of two engines and with the engines in the wings, the empty space in the nose allowed most twin engine fighters to carry a heavy gun armament without the convergence problems faced by fighters with wing mounted guns.

However, with the singular exception of the Lockheed P-38 Lightning, the result was usually an oversize, overweight fighter that could not compete with the agile single seat, single engine day fighters of the time in 1 vs. 1 combat. A few of these twin-engine fighters did operate successfully in the ground attack, reconnaissance and bomber interdiction roles. Those are the twin-engine fighters that will be featured in this article. Most of the successful designs also became night fighters and later carried radar in their noses as well as guns.

Most of the specifications quoted in this article were taken from The Complete Book of Fighters by William Green and Gordon Swanborough. The actual performance of aircraft, even of the same type, varies between individual planes. If your source disagrees with mine, it is understandable and unnecessary to write and tell me so.

Lockheed P-38 Lightning

The Lightning deserves to be first on this list because it is the exception, a twin engine, single seat, all metal monoplane fighter that was clearly a match for the best single engine, single seat fighters of its day. The P-38 has already been well covered in previous articles (See "The Best Fighters of WW II" and "The Lockheed P-38 Lightning" for additional details about the P-38), so I'll just hit some of the high points here.

It was originally designed as a limited production interceptor. However, the P-38 became one of the war's premier long range, air superiority and bomber escort fighters. It was produced in large numbers and saw combat in all theatres of the war. It was particularly well thought of in the Pacific, where the presence of an additional engine (the P-38 flew fine on one engine) saved many lives on long flights home across the Pacific. Both of the top scoring American aces of WW II flew the P-38.

The Lightning lived up to its name; it was fast. It was also highly maneuverable (later models had power boosted ailerons) and climbed very well. The P-38 was one of the best "vertical" fighters of the war.

Its turbocharged, 1600 HP at 26,500', Allison V-12 engines drove counter-rotating propellers, so there was no torque effect on takeoff or landing or in tight turns. It also featured electrically operated dive flaps (P-38J-10 onward), a tricycle landing gear, outstanding forward pilot visibility and very effective landing flaps, all of which are important assets that are highly appreciated by pilots when taking off, landing or maneuvering a high performance airplane on or near the ground. Despite its design (and reputation) as a high altitude fighter, the P-38 proved that it was faster and could out maneuver the nimble German Me 109 and Fw 190 fighters at low altitude. Here are some basic specifications for the P-38J:

  • Maximum speed = 414 MPH at 25,000'
  • Climb to 20,000' = 5.9 minutes
  • Maximum range = 2260 miles at 186 MPH.
  • Weight = 12,780 lbs. (empty); 21,600 lbs. (max. loaded weight)
  • Span = 52'
  • Length = 37' 10"
  • Height = 9' 10"
  • Wing area= 327.5 sq. ft.

The Lightning's "total performance" package differentiates it from the typical twin-engine fighter and is the primary reason for its success as a daytime, air superiority fighter. The P-38's single seat, twin boom, twin vertical stabilizer profile made it instantly recognizable by friend and foe alike; some enemy fighter pilots took to calling it the "Fork-tailed Devil."

Lightning pilots achieved excellent kill ratios against both German and Japanese fighters, the ultimate measure of any air superiority fighter's effectiveness. In post war interviews, Japanese fighter pilots rated the P-38 the best Allied fighter at high altitude. Lightnings were used to shoot down more Japanese aircraft in WW II than any other USAAF fighter.

Due to their long range and high speed, unarmed Lightnings were very successful in the photo reconnaissance role; the F-5 Lightning became the USAAF's premier reconnaissance plane. As the threat posed by enemy fighters waned, Lightnings were adapted to carry a heavy load of external fuel tanks, rockets and bombs. These, along with their twin engines that made them less vulnerable to small caliber ground fire, made them effective fighter-bombers. If my memory serves, something over 12,000 Lightnings of all types were produced.

The Lightning has won over a new generation of fighter aficionados decades after the end of WW II. It has become extremely popular with computer simulation "pilots" and is favored by many of the most successful Warbirds aces. There, the P-38 has earned the title "Super Fighter." The definitive P-38L's excellent climb rate, high speed, heavy armament of 1-20mm cannon + 4-.50 cal. machineguns and long range make it pretty hard to beat.

de Havilland D.H.98 Mosquito

The D.H.98 was designed between 1938-1940 as an unarmed light bomber and became known familiarly as the "wooden wonder," since it was primarily built of wood with plywood skin. Power came from a pair of Rolls Royce Merlin V-12 engines. Both props rotated in the same direction, so torque steer could be substantial. The basic design proved to be very successful and was built under license in Canada and Australia during the war. Mosquitoes served on all British fronts during WW II.

The airplane's exceptional turn of speed and decent handling characteristics practically insured that fighter-bomber, night fighter and photo reconnaissance variants would also be produced. (Mosquitoes may have made their most significant contribution to victory in the latter, largely underappreciated, role.) The two seat Mosquito II, which entered service in March 1942, became the first of these and it was produced in both night fighter and day fighter variants. These fighter versions of the Mosquito normally carried a powerful, forward firing gun armament. Most fighter-bombers carried 4-.303 machineguns and 4-20mm cannon, all mounted in the front of the aircraft. Powered by two 1300 HP Merlin engines, the Mosquito II boasted a climb rate of 3000 ft./min. and a top speed of 370 MPH at 22,000'.

Pilot visibility was restricted to the sides and downward, typical of twin-engine fighters. In the Mosquito, his view was obstructed to the right rear as well, since the pilot sat on the left side of the cabin.

D.H.98's were employed as long range, convoy escort fighters to protect British shipping from German bombers and (in the reverse role) as an effective anti-shipping fighter-bomber. When radar equipped, the Mosquito proved to be excellent at night in the interceptor, long range bomber escort and interdiction roles. Here are some relevant specifications for the FB Mark VI:

  • Maximum speed = 378 MPH at 13,200'
  • Initial climb rate = 1872 ft./min.
  • Range = 1120 miles at 250 MPH.
  • Weight = 13,727 lbs. (empty); max. weight 21,700 lbs.
  • Span = 54' 2"
  • Height = 15' 3"
  • Length = 40' 6"
  • Wing area= 450 sq. ft.

Never intended to be an air superiority fighter, the Mosquito became the RAF's primary night fighter, fighter-bomber and reconnaissance aircraft after its introduction. In these roles, it provided exemplary service and it continued to serve for several years after the end of WW II.

Messerschmitt Bf 110

This twin engine, all metal monoplane fighter served as the Luftwaffe's primary "heavy" fighter throughout the War, from 1939 until the German collapse. The last Bf 110 rolled off the assembly line in March 1945. Power was typically supplied by a pair of DB 601 V-12 engines, both of which turned their propellers in the same direction, creating a lot of torque steer. In other respects, however, it was not difficult to fly. Pilot visibility was good from beneath a long greenhouse type canopy and there was a rear gunner to warn of threats from behind.

It typically carried a two or three man crew (pilot, navigator/radar operator and rear gunner) and was originally designed to fill the Luftwaffe's need for a long range bomber escort. It did well in that role during the Polish and French campaigns, but in the Battle of Britain the Bf 110 proved to be no match for the RAF's single seat Hurricanes and Spitfires in the day fighter role. The Bf 110 was one of the fastest planes around at low altitude, but it did not have the maneuverability or climb rate to prevail against the better single seat fighters of the day.

After that experience, Bf 110 fighters were relegated to the ground attack, night fighter, anti-shipping and long range convoy escort roles, in which they performed well. They were adapted to carry radar, cameras and external stores including drop tanks, gun packs, bombs and rockets. For the remainder of the war the Bf 110 served the Luftwaffe in much the same ways that D.H.98 Mosquito fighters served the RAF. Here are some specifications for the Bf 110F-2 fighter, which was powered by two DB 601F engines of 1350 HP each:

  • Maximum speed = 352 MPH at 17,700'
  • Climb to 19,685' = 9.2 minutes
  • Maximum range on internal fuel = 745 miles
  • Weight = 12,346 lbs. (empty); 15,873 lbs. (normal load)
  • Span = 35' 3.75"
  • Length = 39' 7.25"
  • Height = 13' 6.5"
  • Wing area = 413.33 sq. ft.

Bf 110's also served as bomber "destroyers," successfully opposing the early American bombing raids into German occupied Western Europe. A heavy standard armament of 2-20mm cannons and 4-8mm machine guns in the nose and a single 8mm machine gun in a flexible mount at the rear of the greenhouse canopy made the Bf 110 a formidable adversary for any bomber, including the four engine B-17's and B-24's. After the USAAF was able to provide an adequate number of long range P-38, P-47 and P-51 fighter escorts for their strategic bombers, the Bf 110 was forced to revert to other duties.

It was the Luftwaffe's intention to replace the Bf 110 with the very different Bf 210 in 1942. However, a myriad of technical problems prevented that from happening and the Bf 210 was built in very small numbers. The improved Bf 410 superseded the Bf 210, was produced in moderate numbers (some 1160 total), and phased out of production in September 1944.

Bf 110's rendered valuable service in Western Europe, Norway, North Africa and on the Eastern Front. By the end of the war, approximately 6050 had been built.

Kawasaki Ki-45-KAI

This all metal, twin engine, two seat, multi-role fighter was the result of a complete redesign of the earlier Kawasaki Ki-45 heavy fighter. The design of the original Ki-45 started in December 1937 and first took to the air in January 1939. As far as I can tell, it was never mass produced due to technical difficulties, particularly with the Nakajima Ha-20, 820 HP radial engines.

The Ki-45-KAI prototype first flew in May 1941 and the type entered service in 1942. It was named "Toryu" (Dragon Slayer) by the Japanese and code named "Nick" by the Allies. It served the Japanese Army (to whom it was the Type 2 Two Seat Fighter Model KO) in much the same ways as the Mosquito and Bf 110 served the UK and Germany. The Ki-45-KAI's primary roles became bomber interdiction, anti-shipping, ground support and night fighting. Here are some basic specifications:

  • Maximum speed = 340 MPH at 19,685'
  • Climb to 16,405' = 6.12 minutes
  • Maximum range = 1243 miles
  • Weight = 8146 lbs. (empty); 11,631 lbs. (loaded)
  • Span = 49' 3.15"
  • Length = 36' 1"
  • Height = 12' 1.75" Wing area = 344.46 sq. ft.

The first Toryu versions were powered by Ha-20 engines, but soon a switch was made to the Mitsubishi Ha-102 radial of some 1080 HP. The early fighter models were armed with one forward firing 20mm cannon and two .50 caliber machine guns, while the rear gunner had a single .303 machine gun in a flexible mounting. Later ground and shipping attack models carried two 20mm cannons and a hand loaded (single shot) 37mm cannon and could carry two 550 lb. bombs under the wings, while some night fighter versions were fitted with a forward firing, semi-automatic, 37mm cannon and two upward firing 20mm cannons behind the pilot's cabin. Experiments were made with a forward firing 75mm cannon, but this was not put into series production. In all, 1641 Ki-45-KAI aircraft were built before the end of the war.

Westland Whirlwind

This was a sleek, single seat, twin engine, all metal monoplane interceptor. Like the P-38 and Bf 110, it was designed from the outset as a fighter, not converted from an existing bomber design. It was essentially designed around two RR Peregrine V-12 engines, each rated at 885 HP at 15,000' and 4-20mm cannons mounted in the nose. Like the more powerful P-38, the Whirlwind was designed as a single seat day fighter, not a night fighter or fighter-bomber. The pilot was seated beneath a clear view canopy that provided good all around vision, again much like the P-38. The prototype first flew in October 1938. The RAF ordered about 400 Whirlwinds, but only some 114 were actually built before changing wartime requirements resulted in the cancellation of the remainder. These equipped two RAF squadrons. Here are some specifications for the Whirlwind:

  • Maximum speed = 360 MPH at 15,000"
  • Initial climb rate = 1300 ft./min.
  • Climb to 20,000' = 8.6 minutes
  • Service ceiling = 30,000"
  • Endurance = 1.25 hours (approx.)
  • Weight = 8310 lbs. (empty); 11,388 lbs. (full load inc. bombs)
  • Span = 45'
  • Length = 32' 2"
  • Height = 10' 6"
  • Wing area = 250 sq. ft.

As can be seen from these numbers, the Whirlwind was much smaller than the Bf 110 or Mosquito, further sign of its day fighter roots. In late 1942, the existing Whirlwinds were modified by the addition of wing racks that allowed them to carry a pair of 250 or 500 pound bombs. Operational use ended in November 1943.

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Copyright 2008 by Chuck Hawks. All rights reserved.