Subject: Number One Hundred in the Series--North American F-100 Super Sabre (4 -f 12)

From: [email-masked]
Date: 27 Oct 93 16:48:04 GMT

>From [email-masked]

The F-100B was originally going to be the follow-on to the F-100A.  It 
was pictured as a faster version of the F-100A day fighter, optimized 
to take maximum advantage of the power offered by the J57 jet engine.  

The F-100B project began in 1953 as company design NA-212.  It 
retained the original wing planform of the F-100A but with a 5 percent 
thickness/chord ratio rather than the 7 percent of the F-100A.  An 
upgraded J57 engine was provided, and the aircraft was to be fitted 
with a variable-area inlet duct and a convergent-divergent exhaust 
nozzle.  The fuel load was to be carried in integral wing tanks, no 
provisions being made for the carrying of external fuel tanks.  The 
F-100B was to expected to be approximately the same size and weight as 
the F-100A, and a maximum speed of Mach 1.80 was anticipated.  

At the same time, North American began to study the feasibility of 
adapting the Super Sabre as an all-weather interceptor.  The project 
became known as the "F-100I" (I for *Interceptor*) or "F-100BI", 
although these designations were not official USAF designations.  This 
aircraft was similar to the F-100B except that it had a modified 
cockpit and was fitted with a nose radome.  In order to accommodate 
the radome, the forward fuselage was redesigned with an undernose 
variable-area air intake.  Provision were made for underwing drop 
tanks, and the wing leading edges were to be heated.  The F-100BI was 
intended to bear the same relation to the F-100A as the F-86D did to 
the F-86A.  

The F-100BI did not attract a lot of enthusiasm on the part of the 
USAF.  In November of 1953, consideration was given to adapting the 
NA-212 to a fighter-bomber role.  Six hardpoints were added to the 
wing, and the wing structure, control, and cockpit were revised 
accordingly.  Single-point refuelling capability was added and the 
windshield and canopy were revised to improve the pilot's view.  A 
retractable tailskid was installed and the flight control system was 
upgraded by the addition of pitch and yaw dampers.  The USAF seemed to 
be moderately interested in this fighter-bomber version.  

On May 16, 1954, North American directed that all work on the F-100B 
interceptor project be terminated and that all work now be 
concentrated on the fighter-bomber adaptation.  The nose radome and 
the chin intake of the interceptor version were, however, to be 
retained.  

In the meantime NAA engineers had discovered that low-speed handling 
could be improved and landing speeds lowered by about 30 mph if an 
inboard blown flap were used for boundary layer control.  

On June 11, 1954, the USAF authorized a contract for 33 F-100B fighter 
bombers.  On July 8, 1954, the designation was officially changed to 
F-107A, the USAF concluding that since this aircraft was so vastly 
different from the original F-100A it deserved a completely new 
fighter designation.  

The vertical tail of the F-107A was redesigned as a single-piece slab, 
A similar innovation was adopted for the North American A3J (later 
A-5) Vigilante carrier-based attack bomber.  A spoiler-slot-deflector 
system provided lateral control.  The major offensive load was to 
consist of a nuclear weapon carried semi-submerged in the fuselage 
belly on the centerline.  Unfortunately, wind tunnel tests showed that 
there would be major problems with weapon release and separation 
caused by airflow interference from the nose radome and chin air 
intake.  In order to correct this problem, it was decided to move the 
air intake from the nose to the top of the fuselage just behind the 
cockpit.  

The first F-107A (serial number 55-5118) took off on its maiden flight 
on September 10, 1956 at Edwards AFB with NAA test pilot Bob Baker at 
the controls.  It went supersonic on its first flight.  

A variable air inlet duct was installed on the third prototype 
(55-5120).  This variable geometry duct did not perform very well, but 
variable geometry intakes were in their infancy at the time.  

The F-107A found itself in direct competition with the Republic F-105 
Thunderchief for production orders.  In 1957, the USAF decided to go 
with the F-105, and the F-107 was relegated to aerodynamic testing 
duties.  The first and third F-107As were turned over to NACA for high 
speed flight testing work.  The first F-107A was so mechanically 
unreliable that it was grounded by NACA after only four flights and 
was scavenged for spare parts to keep the other one flying.  

The flight testing of the variable geometry intake of the third 
machine (55-5120) was cut short because of its mechanical problems.  
Eventually, the inlet was fixed in position, limiting top speed to 
Mach 1.2.  

The third F-107A (55-5120) was damaged on September 1, 1959 when test 
pilot Scott Crossfield was forced to abort a takeoff because of 
control problems.  Both tires blew and the left brake burst into 
flames.  The resulting damage was too severe for economical repair, 
and NACA decided to scrap the aircraft.  

The other two F-107As still survive.  F-107A number 55-5118 is in the 
Pima Air Museum in Tucson, Arizona.  F-107A number 55-5119 is in the 
Air Force Museum at Wright-Patterson AFB in Ohio.  

Specification of the YF-107A: 

One Pratt & Whitney YJ75-P-9, 17,200 lb.st. dry and 24,500 lb.st.  
with afterburning.  Maximum speed: 890 mph at sea level, 1295 mph at 
36,000 feet.  Initial climb rate: 39,900 feet per minute.  Service 
ceiling 53,200 feet.  Normal range 788 miles, maximum range 2428 
miles.  Dimensions were wingspan 36 feet 7 inches, length 61 feet 10 
inches, height 19 feet 8 inches, wing area 376 square feet.  Weights 
were 22,696 pounds empty, 39,755 pounds gross, 41,537 pounds maximum 
takeoff.  Armament was to consist of four 20-mm cannon, plus six 
underwing hardpoints for stores.  A centerline position was provided 
for a recessed store.  

Sources:

  North American F-100 Super Sabre, David A. Anderton, Osprey, 1987

  The North American F-100 Super Sabre, Ray Wagner, Aircraft in Profile,
  1965.

  United States Military Aircraft Since 1909, Gordon Swanborough and
  Peter M. Bowers, Smithsonian, 1989.

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

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

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

  Post-World War II Fighters, 1945-1973, Marcelle Size Knaack,
  Office of Air Force History, 1986. 

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