Subject: Number Eighty-Three in the Series--Bell XP-83

From: [email-masked]
Date: 14 Jul 93 16:30:52 GMT

>From [email-masked]

One of the primary weaknesses of early jet fighters was their voracious 
appetite for fuel, resulting in a short range and a limited endurance 
as compared to conventional piston-engined fighters.  In March of 
1944, the Bell Aircraft Corporation was asked by the USAAF to 
construct a jet fighter with extended radius to overcome some of these 
limitations.  A Letter Contract for two prototypes was issued on March 
29, 1944.  The designation XP-83 was assigned.  

Bell had actually been working on an interceptor design since March of 
1943 under the company designation of Model 40.  In April, in response 
to the USAAF's requirement, the Model 40 was reconfigured as a 
long-range escort fighter.  The Bell Model 40 retained the basic 
overall configuration of the earlier P-59A Airacomet, the first US 
jet-propelled aircraft.  Twin General Electric I-40 (J33) turbojets 
were installed in housings underneath the wing roots, adjacent to the 
fuselage.  This arrangement had the advantage in that no appreciable 
asymmetric forces were exerted if one engine went out.  In addition, 
no fuselage space was occupied by engines, leaving internal fuselage 
capacity free for fuel tankage and armament.  

The rather large and bulky fuselage was of all-metal semimonocoque 
construction.  A fully-retractable tricycle undercarriage was fitted.  
Internal fuel capacity was a capacious 1150 US gall.  In addition, a 
pair of 250 US gall drop tanks could be carried.  The ailerons were 
hydraulically-operated, and the flaps were electrically-controlled.  A 
pressurized cabin was provided.  The cockpit had a small, low canopy 
with a very sloping windscreen.  The proposed armanent was to be six 
0.50-in machine guns with 300 rpg, all guns being mounted in the nose.  
However, alternative armament schemes of four 20-mm or 37-mm cannon 
and even a battery of 20 (!!!) 0.50-in machine guns were also 
considered.  

A USAAF contract for two XP-83 prototypes was awarded on July 21, 
1944, confirming the Letter Contract of March.  Serials were 44-84990 
and 44-94991.  Only seven months after the awarding of the contract, 
the first prototype (44-84990) was flown on February 25, 1945 by chief 
Bell test pilot Jack Woolams.  The aircraft proved to be underpowered 
and somewhat unstable.  The close proximity of the turbojets was found 
to have the unintended side effect of allowing the hot jet exhaust 
gases to buckle the tailplane during run-ups on the ground unless fire 
trucks were standing by to spray cooling water on the rear fuselage.

The second prototype (44-84991) flew on October 19, 1945.  It had a 
slightly different bubble canopy and a somewhat longer nose to 
accommodate a heavier armament of six 0.60-inch T17E3 machine guns.  
This aircraft was used in gunnery tests at Wright Field in Ohio.  

The tailplane overheating problem was cured by modifing the tailpipes 
so that they angled outwards.  Wind tunnel tests showed that an 
18-inch extension of the vertical tail would cure the stability 
problems, but it is not certain whether or not this modification was 
actually carried out.  

The performance of the XP-83 was rather disappointing, and no series 
production was ordered.  Apart from its range, the XP-83 offered no 
significant advantages over the Lockheed P-80 Shooting Star which was 
already in production, and further work on the XP-83 project was 
abandoned.  

Following the abandonment of work on the XP-83, the two prototypes 
were used for a short time as test beds for other development work.  
The first XP-83 was used in a ramjet engine test program, in which a 
pair of experimental ramjets were slung under the wings.  It was 
intended that the aircraft would be able to fly on ramjet power only, 
once sufficient flying speed was obtained.  A hatch was cut in the 
belly to provide entry into the aft fuselage, and an engineer's 
station was provided in the fuselage behind the pilot.  However, on 
September 14, 1946, just as the test program was beginning, one of the 
ramjets caught fire during a test flight, forcing pilot Chalmers 
Goodlin and engineer Charles Fay to parachute to safety.  The XP-83 
was destroyed in the ensuing crash.  

I am unaware of the fate of the second XP-83.  

Specification of the XP-83: Two 4000-lb.st. General Electric J33-GE-5 
centrifugally-fed turbojets.  Maximum speed was 522 mph at 15,660 
feet.  Range on internal fuel was 1730 miles at 30,000 feet.  With two 
250-Imp.gall drop tanks, range was 2050 miles.  Initial climb rate was 
7000 feet per minute, and an altitude of 30,000 feet could be reached 
in 11.5 minutes.  Service ceiling was 45,000 feet.  Weights were 
14,105 pounds empty, 24,090 pounds loaded, 27,500 pounds maximum.  
Dimensions were wingspan 53 feet 0 inches, length 44 feet 10 inches, 
height 15 feet 3 inches, wing area 431 square feet.  

Sources: 

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

  The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.  

  War Planes of the Second World War, Fighters, Volume 4, William Green, 
  Doubleday 1964.  

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

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