Subject: Number Ninety-Seven in the Series--Lockheed XF-97

From: [email-masked]
Date: 15 Oct 93 16:21:41 GMT

>From [email-masked]

F-97 was the designation initially applied to the F-94C, the 
rocket-armed version of the Lockheed Starfire two-seat all-weather 
interceptor.  

The F-94A/B Starfire had been evolved by Lockheed as an emergency 
stopgap measure to protect the USAF from Soviet bomber attack until 
more advanced types such as the F-86D Sabre and the Northrop F-89 
Scorpion could be made available in quantity for service.  It was a 
more-or-less straightforward adaptation of the TF-80C two-seat trainer 
(later known as the T-33A).  In July 1948, four months before 
receiving the contract for the first batch of F-94A two-seat 
all-weather interceptor, Lockheed issued a proposal to the USAF for a 
more advanced all-weather fighter development of the TF-80C.  The 
project was given the company designation of L-188.  

In order to achieve higher Mach numbers, the L-188 featured a 
completely new wing with reduced thickness.  The speed brakes were 
revised and the fuel capacity was increased.  A more advanced Hughes 
E-5 fire control system with APG-40 radar was to be used.  The machine 
gun armament of the F-94A was to be replaced by an all-rocket 
armament.  Since more power was clearly needed, a Pratt & Whitney J48 
afterburning turbojet was to be fitted.  With afterburning, this 
engine offered 8750 pounds of thrust.  This engine was a license-built 
version of the Rolls-Royce Tay.  The increased engine thrust required 
that the air intakes be revised and made larger.  

The USAF was initially not all that interested in the Lockheed 
proposal, preferring to concentrate on the North American F-86D Sabre 
and the Northrop F-89 Scorpion.  Nevertheless, the USAF thought enough 
of the proposal that they assigned it a new designation of F-97, a new 
F-number being selected for the Lockheed proposal since it was almost 
a complete redesign of the F-94.  

Undeterred by the USAF's initial lukewarm response to their L-188 
proposal, Lockheed decided in 1949 to go ahead with the private 
venture construction of a demonstrator that would combine the L-188 
wing with a F-94A fuselage from which the armament and fire control 
systems were omitted.  Since the J48 was not yet ready, the 
demonstrator was fitted with an imported non-afterburning Rolls-Royce 
Tay.  

Bearing the civil registration N94C, the unarmed demonstrator flew for 
the first time on January 19, 1950, with test pilot Tony LeVier at the 
controls.  It retained the original nose of the F-94A, and had 
non-standard teardrop-shaped centerline-mounted wingtip tanks.  The 
USAF was sufficiently impressed that in February 1950 they purchased 
the unarmed L-188 demonstrator under the designation YF-97.  The 
military serial number 50-955 replaced the original civil registration 
number.  At the same time, the USAF ordered a fully militarized 
prototype YF-97 under the serial number 50-877.  180 production 
examples were ordered under the designation F-97A.  The company 
designation for the F-97A was Model 880.  

Initial trials with the L-188/YF-97 demonstrator turned up several 
problems.  This aircraft, along with the militarized YF-97, was 
progressively modified in order to correct these difficulties.  The 
wing root extension fillet of the original wing was removed to improve 
stall characteristics during landing approach.  The original 
horizontal stabilizer of the F-94 was replaced by power-boosted swept 
surfaces to eliminate an annoying high-frequency vibration at high 
Mach numbers.  Dampers were added to correct aileron buzzing.  
Spoilers were added to improve roll control.  The vertical fin was 
made larger in order to increase directional stability at high speeds.  
The first YF-97 was re-engined with a J48-P-3 engine, rated at 6000 
lb.st.  dry and 8000 lb.st with afterburning.  

On September 12, 1950, the YF-97 was redesignated YF-94C.  Even though 
the new Starfire was almost a completely new aircraft, it was thought 
wise to pretend that the design was simply a "logical extension" of an 
existing aircraft.  The designation of the production F-97As was 
changed to F-94C.  

The F-94C went on to enter USAF service in 1953, some 387 examples 
being built.  Its service was rather brief, being phased out by the 
USAF as more advanced types such as the Convair F-102 Delta Dagger and 
the McDonnell F-101B Voodoo became available.  Many ex-USAF F-94Cs 
were transferred to the Air National Guard.  The last F-94C left ANG 
service in 1959.  

Sources:

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

  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.

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