Subject: Number Eighty in the Series--Lockheed P-80 Shooting Star

From: [email-masked]
Date: 11 Jun 93 16:23:19 GMT

>From [email-masked]

In September 1943, even before the XP-80 had made its first flight, 
Lockheed had proposed a larger and heavier L-141 version powered by 
the more powerful General Electric I-40 turbojet engine (later 
produced by both General Electric and Allison as the J33).  The USAAF 
was sufficiently impressed that they issued a contract for two 
examples under the designation XP-80A.  Serials were 44-83021 and 
44-83022.  

The General Electric I-40 engine that powered the XP-80A had a thrust 
of 4000 pounds, and was fed by intakes relocated a bit further aft to 
a position just below the cockpit windshield.  The wingspan was 39 
feet 0 inches, two feet greater than that of the XP-80, but wing area 
was reduced to 237.6 square feet by using a narrower chord.  Length 
was increased from 32 feet 10 inches to 34 feet 6 inches.  Height 
increased to 11 feet 4 inches.  Weights were considerably greater than 
those of the XP-80, being 7225 pounds empty, 9600 pounds gross, and 
13,780 pounds maximum takeoff.  The increased weight required a 
stronger undercarriage.  Ammunition capacity increased from 200 to 300 
rounds per gun, and internal fuel capacity increased from 285 to 485 
US gallons.  In contrast to the XP-80, the XP-80A was fitted with a 
pressurized cockpit.  

XP-80A 44-83021 flew for the first time on June 10, 1944.  It was 
followed on August 1 by XP-80A 44-83022.  44-83022 was fitted with a 
second seat which could carry an engineering observer.  Early in the 
test program the XP-80A experienced excessively-high cockpit 
temperatures due to a faulty cabin pressurization valve.  This problem 
was easily fixed, but there were more serious problems encountered 
with an unstable airflow through the intake ducts.  Kelly Johnson took 
a ride in the rear seat of 44-83022 in order to try and figure out 
what was causing the problem.  Kelly Johnson was an extremely talented 
aeronautical engineer, and he correctly diagnosed the cause as being 
boundary layer separation along the walls of the duct.  The problem 
was solved by adding a series of boundary layer bleeds along the upper 
edges of the ducts.  This feature was added to all subsequent 
production aircraft.  

The second XP-80A became the first in the Shooting Star series to 
carry a 165 US-gallon drop tank underneath each wingtip.  When 
carried, these tanks actually lowered rather than increased the drag.  

The first XP-80A crashed on March 20, 1945, but test pilot Tony LeVier 
managed to parachute to safety and escaped with only back injuries.  
The second XP-80A was later used as a testbed for the Westinghouse J34 
axial-flow turbojet in support of the XP-90 program.  

Sources:

  War Planes of the Second World War, Fighters, Volume Four, William Green,
  Doubleday, 1964.

  The American Fighter, Enzo Anguluci and Peter Bowers, Orion Books, 1987.

  United States Military Aircraft since 1909, Gordon Swanborough and Peter 
  M. Bowers, Smithsonian Institution Press, 1989.

  Fighters of the United States Air Force, Robert F. Dorr and David Donald,
  Temple Press Aerospace, 1990.

  American Combat Planes, Ray Wagner, Third Enlarged Edition, Doubleday, 1982.

  Lockheed Aircraft since 1913, Rene J. Francillon, Naval Institute Press,
  1987.

Joe Baugher		AT&T Bell Laboratories   	
2000 North Naperville Road      Naperville, Illinois 60566-7033