Subject: Number 105 in the Series--Republic F-105 Thunderchief (5 of 9)

From: [email-masked]
Date: 10 Feb 94 17:23:45 GMT

>From [email-masked]

The F-105D was the all-weather version of the F-105, differing in 
having a slightly longer and wider nose housing an NASARR R-14A 
all-purpose monopulse radar.  This radar was optimized in both 
air-to-ground and air-to-air modes and was capable of performing both 
low-level and high-level missions.  The aircraft was equipped with a 
General Electric FC-5 flight control system which operated in 
conjunction with the R-14A radar to provide the F-105D with full 
all-weather capability.  The system comprised a toss bomb computer, a 
sight system, an AN/APN-131 Doppler navigator, an air data computer, 
missile launch computer, autopilot, and search and ranging radar.  
The radar installation also incorporates a terrain guidance mode
which permits the pilot to let down through bad weather in 
unfamiliar territory and to hug the ground to avoid detection.

The F-105D was powered by a higher thrust J75-P-19W engine equipped 
with water injection.  A new cockpit was provided with a vertical 
instrument panel.  The higher gross weight of the F-105D required
the provision of a strong main landing gear and more robust brakes.

Externally, the F-105D could be distinguished from the B by its larger 
radome for the NASARR radar.  The F-105B carried only a simple radar 
ranging sight for its cannon, so its radome was considerably smaller.  
In addition, the F-105D had a pitot tube mounted on the extreme tip of 
the nose.  The aircraft were otherwise quite similar.  

The F-105D had an arrestor hook mounted on the rear of the ventral
fin.  This hook was intended to engage a wire in case the aircraft
overshot the end of the runway during a landing.  The Thunderchief
was certainly NOT ever intended for carrier-based operations. :-)

The first F-105D (58-1146) flew on June 9, 1959 with Lin Hendrix at 
the controls.  The first F-105D was accepted by the TAC at Nellis AFB 
on September 28, 1960.  The initial contract for 59 F-105Ds was 
increased to nearly 300 by the end of 1961.  Ultimately, 610 F-105Ds 
were built, making it the major variant of the Thunderchief.  

The first unit to receive the new F-105D was the 335th Tactical 
Fighter Squadron, replacing its older F-105Bs for the new 
Thunderchief.  The Thunderchief's first European deployment came in 
May of 1961, when the 36th TFW based at Bitburg in Germany received 
its first F-105Ds.  

In June of 1961, the F-105D demonstrated its ability to carry and 
deliver seven tons of bombs during special tests at Elgin AFB in 
Florida.  This was the heaviest load of bombs ever carried by a 
single-engined fighter.  This feat was repeated in October of 1961 at 
Fort Bragg, North Carolina, with President Kennedy being one of the 
eyewitnesses.  

All F-105Ds were briefly grounded in December 1961 after the 
aircraft's main fuselage frame failed during a laboratory fatigue test 
at Wright-Patterson AFB.  However, subsequent tests indicated that the 
frame had retained considerable strength even after cracking.  
Republic had suitable adapters and tools to do the required corrective 
work.  

In June of 1962, there were two major accidents at Nellis AFB, and all 
F-105Bs and Ds were grounded for correction of chafing and flight 
control deficiencies.  These modifications took a lot longer than 
expected and were not fully completed until mid-1964.  However, the 
F-105D continued to experience a series of accidents due to engine 
failures, fuel leaks and malfunctions of the fuel venting system.  
These problems were not fully corrected until 1967.  

A total of 610 F-105Ds was built between 1960 and 1964.  The
F-105D was originally intended for the nuclear strike role, with the
primary armament being a "special store" (a euphemism for a nuclear
weapon) housed in the internal weapons bay.  Typical internal
weapons load included a Mk 28 or a Mk 43 nuclear bomb.  However,
an Mk 61 could be carried underneath the left or right inboard
underwing pylon and a Mk 57 or a Mk 61 could be carried underneath
the centerline pylon.  As nuclear war became less and less likely,
the nuclear weapon carried in the internal weapons bay was usually
replaced by a 390-gallon fuel tank, the offensive load being carried
on four underwing pylons and on a pylon mounted underneath the
fuselage on the centerline.  From the F-105D-20-RE production block
onward, the Thunderchiefs had increased emphasis on conventional 
weapons delivery, with the capability of carrying a wide-ranging  
combination of external stores underneath the wings and fuselage.

The F-105Ds replaced the F-105Bs flown by the 4th Tactical Fighter 
Wing.  They were also supplied to the 4520th Combat Crew Training Wing 
based at Nellis AFB plus the 36th TFW (22nd, 23rd, and 53rd 
Squadrons), the 49th TFW (7th, 8th, and 9th Squadrons), the 18th 
Fighter Bomber Wing (12th, 44th, and 67th squadrons), the 355th FBW 
(354th and 357th Squadrons), and the 388th TFW.  The 36th and 49th 
Wings went to Europe at the end of 1961 to provide NATO with nuclear 
strike capability.  The 8th and 18th Wings were stationed in Japan 
from 1962 onwards.  

The last few F-105Ds off the production line (production block -31)
were given the capability of refuelling from either a flying boom
or a hose-drogue type of tanker.  This was done by fitting a
flush-mounted retractable door-type receptacle in front of the
windshield which could accept a flying-boom type of midair-refuelling
probe.

In service, the seven TAC wings using the F-105D experienced lots of 
accidents and operational problems which led to no less than ten 
groundings.  The aircraft came to be known under the nickname "Thud" 
and had a questionable reputation of being too heavy, having too long 
a takeoff run, and being a maintenance nightmare.  

On March 1, 1965 F-105Ds based at Da Nang began bombing raids over 
North Vietnam.  The Thunderchief made an excellent tactical bomber.  
With multiple ejector racks it could carry an impressive load of 
external fuel, ECM gear, and eight 750-pound bombs on long range 
missions.  On short range missions, it could carry sixteen 750-pound 
bombs.  Alternative loads were two 3000-pound bombs or three drop 
tanks.  It could also carry the Martin AGM-12 Bullpup air-to-surface 
missiles, but these were to prove almost useless in Vietnam against 
hard targets.  The F-105D could carry 2.75-inch rocket pods, napalm 
canisters, as well as four AIM-9 Sidewinder infrared homing air-to-air 
missiles.  The M61A1 Gatling-type 20-mm cannon proved invaluable in 
the dual role of air-to-air combat and ground strafing.  With its size 
and range, the F-105D could carry twice the bombload further and 
faster than the F-100.  On a typical mission over North Vietnam, the 
F-105D would carry six 750-pound bombs or five 1000-pound bombs, along 
with two 450 US-gallon drop tanks.  

Initially, the hydraulic system was extremely prone to failure due to 
combat damage, but once it was improved the F-105D could take severe 
battle damage and still keep flying.  The 255th and 388th Tactical 
Fighter Wings based in Thailand used the F-105D to carry the brunt of 
the air war to North Vietnam. 

However, the F-105D was somewhat less successful as a fighter, being 
hard pressed by enemy MiG-17 and MiG-21 fighters.  It had a wing 
loading that was much too high to be able to maneuver effectively 
against the more nimble MiGs.  However, when jumped by MiGs, the 
enormous thrust of the J75 engine enabled a cleaned-up Thunderchief to 
leave its pursuers rapidly behind in a cloud of half-burned kerosene.  
However, the F-105D did manage to shoot down 27 enemy fighters during 
the course of 1966 and 1967.  Most of these kills were by the 20-mm 
Vulcan cannon, although two were downed by Sidewinders.  

Throughout the Southeast Asia War, the F-105D was repeatedly modified 
to meet changing conditions.  They were retrofitted with armor plating, 
backup flight control systems, X-band beacons, new radar altimeters, 
and AN/ASG-19 Thunderstick gun bombsights which provided for automatic 
or manual and blind or visual weapons delivery, with automatic or 
manually-controlled weapons release.  The pilot ejector seat was 
improved, and AN/APR-25(U)-26(V) radar homing and warning (RHAW)
antennae were added to the tip of the vertical fin to help warn 
the pilot when MiGs were sneaking up on his tail.  In addition, 
the refueling probes of the early F-105Ds were brought up to later
standards.  Several F-105Ds were provided with a combat camera
mounted in a protrusion on the lower nose just behind the radome.
Many F-105Ds were fitted in the field with ram air intake scoops
on the rear fuselage to address an afterburner cooling problem 
which has resulted in some engine fires.

All throughout the 1960s, the AN/ARN-85 LORAN system of the F-105D had 
caused severe problems during combat because of its poor reliability.  
In 1969, 30 F-105Ds were re-equipped with AN/ARN-92 LORAN equipment 
for more precise navigation.  These planes could be identified by the 
presence of a long dorsal spine extending all the way from the canopy 
to the tail fin.  They were known as *Thunderstick IIs*, or T-Stick II 
for short.  The first T-Stick aircraft flew on August 9, 1969.  They 
served with the 23rt TFW in the continental US, but never saw any 
combat.  

The most famous F-105D raid occurred on August 2, 1967, when pilots of 
the 335th and 388th TRS attacked and heavily damaged the Paul Doumer 
bridge north of Hanoi.  This bridge was vital for moving war supplies 
between China and North Vietnam, and was a prime target.  However, the 
bridge was eventually repaired.  Nevertheless, it was hit and knocked 
down again--several times.  

By 1969, F-105Ds had been superseded by F-4 Phantoms in bombing raids 
over North Vietnam.  The F-105D was then confined to targets in Laos 
where the anti-aircraft fire was less.  

In 1969, the 388th TFW gave up its F-105Ds and the 355th TFW returned 
with its aircraft to the USA in November of 1970, bring to an end the 
combat use of the single-seat Thunderchief.  

Over 20,000 combat missions were flown by Thunderchiefs in Vietnam.  A 
total of over 350 Thunderchiefs (Ds and Fs) were lost in combat, most 
of them to North Vietnamese anti-aircraft fire.  This was over half of 
all Thunderchiefs built.  At one point in 1965-1968, it was calculated 
that a F-105 pilot stood only a 75 percent chance of surviving 100 
missions over North Vietnam.  Although the total number of losses was
rather high, the actual loss rate was not that bad considering the
total number of missions that were flown. 

The few Thunderchiefs to survive combat in Vietnam finished their 
careers with the 23rd Tactical Fighter Wing and the 388th.  They were 
handed over to units of the Air National Guard, which continued to 
operate them until 1983.  

The last Air Force reserve unit to operate the F-105D, the 466th TFS, 
made the last flight with the type on February 25, 1984.  

Perhaps because of its complexity, the F-105D was never exported to 
any foreign air forces.  

Specification of F-105D: 

One Pratt & Whitney J75-P-19W turbojet, rated at 17,200 lb.s.t. dry 
and 26,500 lb.s.t. with afterburner.  Maximum speed: 1420 mph at 
38,000 feet, 1372 mph at 36,000 feet, 1122 mph at 50,000 feet, 836 mph 
at sea level.  Stalling speed was 208 mph.  Initial climb rate was 
34,500 feet per minute (clean).  Service ceiling was 32,100 feet, 
combat ceiling was 48,500 feet, and absolute ceiling was 50,000 feet.  
Combat range was 778 miles and maximum range with full external fuel 
was 2208 miles.  The internal weapons bay can accommodate a 390 US  
gallon auxiliary tank which supplements the normal internal fuel load 
of 1160 US gallons.  This fuel load can be further augmented by a 450
or 650 US gall external tank on the fuselage centerline plus a 450 US  
gallon tank on each of the inboard underwing stores pylons.  Dimensions: 
wingspan 34 feet 11 inches, length 64 feet 3 inches, height 19 feet 8 
inches, wing area 385 square feet.  Weights: 27,500 pounds empty, 
35,637 pounds combat, 48,400 pounds gross, 52,546 pounds maximum 
takeoff.  Armed with one 20-mm M61A1 rotary cannon with 1028 rounds.  
Up to 8,000 pounds of ordinance could be carried in the internal 
weapons bay.  In addition, a further 6000 pounds of ordinance could be 
carried on external weapons racks (four underneath the wings, one 
underneath the fuselage).  

Serials of F-105D:

58-1146/1148		Republic F-105D-1-RE Thunderchief
58-1149/1173		Republic F-105D-5-RE Thunderchief
58-1174/1190		Cancelled contract (believe for F-105)
59-1717/1757		Republic F-105D-5-RE Thunderchief
59-1758/1774		Republic F-105D-6-RE Thunderchief
59-1775/1816		cancelled contract for F-105D
59-1817/1826		Republic F-105D-6-RE Thunderchief
60-0409/0426		Republic F-105D-6-RE Thunderchief         
60-0427/0535		Republic F-105D-10-RE Thunderchief         
60-5374/5385		Republic F-105D-10-RE Thunderchief         
61-041/106		Republic F-105D-15-RE Thunderchief
61-107/161		Republic F-105D-20-RE Thunderchief
61-162/220		Republic F-105D-25-RE Thunderchief
62-4217/4237		Republic F-105D-25-RE Thunderchief
62-4238/4276		Republic F-105D-30-RE Thunderchief
62-4277/4411		Republic F-105D-31-RE Thunderchief

Sources:

  The Illustrated Encyclopedia of Aircraft Armament, Bill Gunston,   
  Orion, 1988.

  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. 

  The World Guide to Combat Planes, William Green, MacDonald, London, 1966

  The World's Fighting Planes, William Green, Doubleday, 1964.

  The Aircraft of the World, William Green and Gerald Pollinger, Doubleday,
  1965.

  The Thunder Factory, Joshua Stoff, Motorbooks, 1990.

  F-105 Thunderchief in Detail and Scale, Bert Kinzey, Kalmbach Books,
  1993.   

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