THE 456th FIGHTER INTERCEPTOR SQUADRON

T PROTECTORS OF  S. A. C.

 

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The XP-38

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With the contract awarded to Lockheed, the design team then focused on creating the prototype. This was now designated as the XP-38 by the military. The XP-38 was constructed using butt-jointed flush riveted external surfaces developed by James McMinn Gershler. The control surfaces were also metal coated. Kelly Johnson also designed an intercooler, which would form part of the leading edge of the wing for aerodynamic and mechanical efficiency. Finally in January 1939, and $761,000 later, the XP-38 was ready for its maiden flight.

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The XP-38

The XP-38 arrived at March Field on December 31, 1938. After a couple of weeks performing the final preparations, the XP-38 began initial testing. Lt. Ben Kelsey was ordered to monitor the design process, and when the prototype was ready, he would be behind the controls. Kelsey began the flight-testing by taxing the aircraft along the runway and was able to determine that the braking system was inadequate. His aircraft was unable to stop and scattered a construction crew working at the end of the runway. Finally, the XP-38 was ready to take flight for the first time. January 27, 1939 saw the XP-38 ready for flight. Kelsey steadily added power to the two Alison engines and lifted off the runway. Shortly after takeoff, the flaps began to shake and vibrate. Unknown to Kelsey, three out of the four aluminum support rods had failed, and allowed the flaps to run out of the stops. If all four support rods failed, the aircraft most likely would be unmanageable. Kelsey throttled back and eased his way back towards the runway. He did not want to abandon the aircraft, which was a result of many months of hard work by Lockheed. Unable to use flaps for landing, he came is faster than normal landing speeds. He flared out between 120-130 mph and was at 18 degrees. The XP-38 actually was dragging its tail on the runway, causing sparks to fly. Kelsey was optimistic about the flight, and even excitedly proclaimed that the aircraft did not stall even at an extreme angle of attack. This first flight of the P-38 was marked with a large degree of excitement, even though it only lasted a short time.

The engineers examined the aircraft, and it was determined that the problem was a result of inefficient flap seals and support rods. With those two problems addressed, and with enhanced brakes, the aircraft was ready for its second flight. Kelsey once again took the aircraft up on February 5, 1939. A third flight of the XP-38 revealed some longitudinal instability, which Kelly Johnson resolved by adding an extra seven feet of horizontal stabilizer outside of the fins on each side. Further testing revealed buffeting elevator problems. This was caused by the prop-wash from the inboard wing area. Switching engines resolved this problem, which created the counter-rotating engine characteristic of the P-38.

Three additional flights were conducted which brought the total testing time through February 10, to 4 hours and 49 minutes. Since the first flight problems, no major problems were encountered throughout this short time of testing. It was time to move from March Field, and the military wanted to use this move to showcase their new aircraft to the public. A decision was made to use this move to perform a record breaking flight across the continent, thus breaking the existing speed record. On February 11, 1939, Lt. Kelsey lifted off from March Field and proceeded to fly to Amarillo, Texas. This three-hour flight was uneventful. Kelsey was benefiting from a tailwind and made his way across St. Louis and headed to Wright Field in Ohio. There he met with General Hap Arnold, and he gave Kelsey a final approval to continue the flight. Up to this point, the XP-38 was performing flawless, and showed no evidence of any problems. However, this would soon change.

The plan was for Kelsey to take off from March Field and proceed to Mitchel Field, his final destination. Nobody at Mitchell Field was informed of any record-breaking flights, nor were they expecting a new prototype to make its way there. Kelsey also did not inform the Mitchell Field tower of his record, and did not ask for any time readings or insist on any priority. Instead, he was placed in a long landing pattern behind three much slower aircraft. Kelsey describes what happened then.

"I did not give it a second thought when the tower instructed me to take a position behind the PB-2A because I had to get the plane slowed down for flap extension anyway. I did not even think of icing because we had none of it before. When I added power, I was really surprised to see those damn engines just sit there and idle at around 1,500 rpm. If the engines just quit, I thought at the moment and have often thought, while I was going down…if they had just stopped all together, I would have kicked it off to the right and would have landed in an open field. It would have been a reasonably good landing and we would have had minimal damage."

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The Wreckage Of The XP-38

The XP-38 ended up crashing onto the Cold Stream Golf Course at Hampstead, Long Island. It slashed through some trees, but a sand trap ended up doing the most damage. The aircraft was reasonably intact, but it was twisted, which prevented it from being repaired in any way. Spectators quickly approached the crash site and were surprised to see Kelsey unhurt. This crash also demonstrated the strength and durability of the airframe, would be a characteristic of the P-38 throughout the entire war.

Arguments have been made about the crash. Some people believed that the program was not set back too much because there was already many improvements planned for the next model, the YP-38. Kelly Johnson put down some improvements he was working on in Report No. 1483. He calculated a top speed of 403 mph at critical altitude on 1150 brake hp per engine. All he needed to meet for the original specifications was 360 mph.

 

Recommended Alteration
Calculated Speed Change
Redesign Prestone coolant radiators:
+8
Improved turbo-supercharger installation:
+4
Revised oil cooler inlet:
+3
Reduction in exhaust cooling duct size:
+2
Weight reduction of 800 - 1,000 lbs:
+2
Increase horizontal stabilizer area by 7 sq. ft.:
-1.2
Armament installation:
-7.8
 
 
Net Change:
+10 MPH

Looking back at the testing process of the XP-38, Tony LeVier was critical of the record attempt. He argued that the crash did indeed cause a significant delay in the development of the P-38 program. "It was a grand idea, but the only thing a speed record would give them was some newspaper headline for a day and that's about all. Instead of waiting a few weeks until we knew more about the airplane, they took it when it had hardly been tested." He further states that, "What did it do? It set the P-38 back about two years because we had to start from scratch and build another prototype airplane and run a whole new test program, and it was the best fighter plane we had at that time. That incident may very well have lengthened the war."

An investigation was immediately launched to probe the cause for the crash. The XP-38 crash was attributed to either vapor lock or possibly icing of the engines. General Arnold and Lt. Kelsey were summoned to Washington to discuss the circumstances of the crash and the possible future of the P-38 developmental program. Satisfied with the state of the P-38 program, the military decided to order thirteen additional YP-38s from Lockheed.

 

The News Story Of The XP-38 Crash

 

"Mystery" Plane Crashes at End of Test Speed Hop; Fails to Break Hughes Mark

New York, February 11 (1939)-(AP)-A new secret twin-motor Army pursuit monoplane crashed into a tree on the edge of Mitchel Field on Long Island tonight at the end of a near-record transcontinental test flight.

The pilot and sole occupant, Lieutenant Ben S. Kelsey, crack test flier, was saved from serious injury by the plane's all-steel cabin.

Kelsey took off from March Field, Calif., at 9:12 a.m. (Eastern Standard Time), stopped briefly at Amarillo, Texas, and Dayton, Ohio, and arrived here at 4:57 p.m. His elapsed time of 7 hours 45 minutes was only 16 minutes and 35 seconds longer than Howard Hughes' 1937 Burbank, Calif.-Newark, N.J. nonstop record.

He apparently overshot the field, observers said, and zoomed the motors to pick up speed and altitude. The right motor appeared to choke, sending him into a steep right turn.

As Kelsey cut the throttle again, the plane slipped down and sheared off the tops of trees bordering the field, the undercarriage caught in a thirty-five-foot tree, and the plane plunged down into a sand pit on the Cold Stream Golf Course.

Bystanders pulled Kelsey out of the wreckage. He was taken to a hospital with cuts on one eye and one hand, and suffering from shock. He was released after examination.

Scores of cars jammed around the spot. Field officials threw a fifty-man guard around the wreckage and rushed the plane's instruments to the field office, their condition undetermined.

Colonel James Chaney, field commandant, called an inquiry board into session immediately, with Kelsey present. The findings were expected to be kept secret and sent to Washington in an army plane.

The weather at the time of the crash was clear, with a light shifting wind. At the time of the crash it was blowing southeast.

The plane was a new Lockheed, the Army's first twin-engined pursuit plane, completed at the Lockheed Burbank plant two weeks ago and capable of doing 350 miles an hour.

It was an all-metal single-seater, with stratosphere operating equipment, tricycle undercarriage, and super-high lift devices.

It was designed to carry a nest of high-power machine guns, but none today. Its designation was XP-38.

Kelsey left Amarillo at 12:21 p.m. (E.S.T.), stopped at Dayton for 20 minutes, and took off at 3:34 p.m. (E.S.T.)

His distance was estimated officially at about 2,400 miles. Hughes flight was about 2,587 miles.

Kelsey, 33, is married and is regularly assigned to the laboratory division of Wright Field, Dayton.

 

The Air Force Museum

 

 

The XP-38 "Lighting"

Joe Baugher

The Lockheed P-38 Lightning racked up an impressive series of "firsts"--it was the first Lockheed-designed military aircraft to go into series production, it was the first twin-engined interceptor to serve with the USAAC, it was the first production fighter powered by the Allison V-1710 in-line engine, it was the first modern fighter equipped with a tricycle landing gear, it was the first American plane to use butt-jointed flush riveted external surfaces, it was the first to make extensive use of stainless steel, it was the first fighter to use a bubble canopy right from the start, it was the first fighter with speeds over 400 mph, it was the first US twin-boom fighter to go into production, it was the first USAAF fighter to shoot down a German aircraft, it was the first USAAF fighter to carry out an escort mission to Berlin, it was the first USAAF plane to land in Japan after that country had surrendered, it was the heaviest US single-seat fighter of World War 2, it was the only American fighter in production at the time of Pearl Harbor to be still in production at the war's end, and it accounted for more Japanese aircraft destroyed in combat than any other US fighter.

A total of 10,037 Lockheed Lightnings were built.

Lockheed was invited along with Boeing, Consolidated, Curtiss, Douglas, and Vultee to take part in a USAAC design competition X-608 for a twin-engined high-altitude interceptor. The specification called for a maximum speed of at least 360 mph at 20,000 feet and 290 mph at sea level, an endurance at full throttle of one hour at 20,000 feet, and the ability to take off and land over a 50-foot obstacle within 2200 feet.

The Lockheed design staff was headed by Hall L. Hibbard. Working with Hibbard was the soon-to-be famous Clarence L. "Kelly" Johnson. After studying a lot of different designs, Hibbard and Johnson finally settled on a twin-boom design with each boom extending aft of the engine and the pilot sitting in an enclosed cockpit in a central nacelle. Each boom was to house one of the new 1150 hp Allison V-1710C twelve-cylinder liquid-cooled engine with an exhaust-driven turbosupercharger. The Allison engine at that time had just completed a 150-hour type approval test at 1000 hp. The central nacelle contained a forward-firing armament of one cannon and four 0.50-in machine guns. This armament was quite heavy for its time, the standard USAAC armament of the day being one 0.30-in and one 0.50-in machine guns. One advantage of the twin-boom layout was the possibility of installing the armament in the central nacelle, unhampered by synchronizing gear and allowing sighting of the parallel streams of fire up to the maximum range of 1000 yards. Tail surfaces consisted of a fin and rudder at the end of each boom and a horizontal tailplane and elevator between the booms. It was anticipated that the twin fin-and-rudder tail assembly would increase the effective aspect ratio of the tailplane by the endplate effect, thereby providing stability over a large c.g. range. At 14,800 pounds, the XP-38 weighed more than a bombed-up Bristol Blenheim I, at that time the standard British medium bomber. Fowler flaps were fitted between the ailerons and the booms and between the booms beneath the trailing edge of the wing center section.

The project was given the company designation Model 22-64-01. Lockheed promised a maximum speed of over 400 mph. Although the USAAC was somewhat skeptical about so radical a design, the Model 22 won Design Competition X-608 and on June 23, 1937, Lockheed was awarded a contract for one XP-38 prototype (Ser No 37-457). Construction began in July 1938. Construction proceeded rather rapidly despite the radical features that it embodied. Few problems were presented by the installation of the Allison V-1710-11/15 (C9) engines, which developed 960 hp at 10,000 feet and 1090 hp at 13,200 feet. Each engine had a General Electric B-1 turbosupercharger. To combat torque, the propellers rotated in opposite directions, a special version of the Allison engine being produced with a left-hand rotating propeller shaft. The engines had inwardly-rotating propellers. No armament was installed on the XP-38.

The XP-38 aircraft was completed in December of 1938. On the last day of the year, the completed XP-38 was stripped down, covered with canvas, and loaded onto three trucks. In great secrecy, the convoy of trucks was escorted by police to March Field, near Riverside, California, where Air Corps Project Officer Lt. Benjamin S. Kelsey was to began the flight testing. However, on the very first ground run, the wheel brakes failed and the XP-38 ended up in a ditch. Lt. Kelsey finally took the XP-38 into the air for the first time on January 27, 1939. The early test flights turned up some problems with the wheel brakes and with vibrations of the flaps, requiring that some modifications be made to the prototype. Maximum speed was 413 mph at 20,000 feet, and an altitude of 20,000 feet could be attained in 6.5 minutes. Service ceiling was 38,000 feet. Empty weight was 11,507 lbs, gross weight was 13,964 lbs, and maximum takeoff weight was 15,416 lbs

Reaction to the first few test flights was highly favorable. In spite of the problems encountered on its first few flights, it was decided to attempt a record transcontinental flight before delivering the XP-38 to the Army at Wright Field. At daybreak on February 11, 1939, Ben Kelsey left March Field destined for Mitchell Field, New York with refueling stops at Amarillo, Texas and Wright Field, Ohio. On the final leg of the flight, the XP-38 lost power as Kelsey was coming in for a landing at Mitchell Field and crashed on a golf course just short of the runway. Fortunately, Lt. Kelsey was unhurt, but the XP-38 was a total loss.

References:

  1. Lockheed Aircraft Since 1913, Rene J. Francillon, Naval Institute Press, 1987
     
  2. The P-38J-M Lockheed Lightning, Profile Publications, Le Roy Weber Profile Publications, Ltd, 1965.
     
  3. War Planes of the Second World War, Fighters, Volume Four, William Green, Doubleday, 1964.
     
  4. Famous Fighters of the Second World War, William Green, Doubleday, 1967.
     
  5. The American Fighter, Enzo Anguluci and Peter Bowers, Orion Books, 1987.
     
  6. Wings of the Weird and Wonderful, Captain Eric Brown, Airlife, 1985.
     
  7. United States Military Aircraft since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian Institution Press, 1989.
     
  8. E-mail from Daniel Stover on P-38 production counts

 

 

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