HISTORY, SPECIFICATIONS, AND PERFORMANCE OF THE REPUBLIC F-105 THUNDERCHIEF

The Aircraft:  Built by the Republic Aviation Corporation (RAC), Farmingdale, Long Island, New York, the F-105D single-place fighter-bomber and F-105F two-place  fighter-bomber/trainer are capable of attaining supersonic speeds at any operational altitude.  The aircraft fuselage is an area rule (coke bottle) type, with swept back wings and empennage.  The aircraft wings incorporate ailerons and spoilers for roll control.  Each wing spoiler is made up of five sections designed to improve roll capabilities at high speed.  The power plant is a twin-spool compressor turbojet engine equipped with an afterburner and water injection.  The retractible tricycle landing gear has a steerable nose wheel which can be engaged or disengaged by the pilot, and automatically disengages after takeoff.  The primary flight controls are hydraulically actuated, and artificial feel devices are used to simulate aerodynamic loads felt by the pilot.  Leading edge (LE) and trailing edge (TE) flaps are provided to increase lift, while a four-section speed brake and a drag chute are installed at the aft end of the fuselage to permit increased drag. Weapon stores are carried in a fuselage-enclosed bomb bay, thereby keeping the aircraft aerodynamically clean.  A variety of externally-carried stores increases its capabilities as a fighter-bomber.  The stores are released manually or automatically by the fire control system.  A hydralically-operated multi-barrelled cannon is also provided.  Provisions are made for single point ground or inflight refueling (IFR).  A ten-liter liquid oxygen (LOX) to gaseous oxygen system is installed for normal crew breathing and  high altitude flight.  (Adapted from T.O. 1F-105D-1, Flight Manual, 15 Jul 1962)

Aircraft History:  The Republic F-105 Thunderchief was the USAF's first supersonic tactical fighter-bomber to be designed and developed from its beginning for this demanding role.  All Air Force fighter-bombers before it were adaptations of aircraft that had originally been developed as "pure" fighters.  The Thunderchief was the largest single-seat, single-engined fighter ever built, with a total production of 690 single-seat F-105Bs/Ds and 143 two-seat F-105F models.  With an unprecedented one-third of its total cost stemming from electronic hardware, the F-105 represented a new dimension in military aircraft technology for the Air Force.  In 1957, USAF General Otto P. Weyland, then-Commander of USAF's Tactical Air Command, called it "..the world's most powerful one-man airplane."  But at a recent 4th Fighter Group reunion, Col Don Blakeslee (WW II P-51 ace, Korean War F-84 pilot, and former commander of the Thunderchief-equipped 18th TFW at Kadena AB, Okinawa) described the F-105 as a "..typical Republic aircraft -- big engine and too goddamn heavy..."

The THUD's story begins before the Korean War. In June 1950,  the Air Force signed an unfunded letter agreement with RAC to study and propose design possibilities for a successor to Republic's famous F-84 "Thunder" series aircraft.  At the time, all of the RAC jets were nicknamed "Hogs" by their pilots because of the unusually large amount of runway they required to get off the runway on takeoff.  These "hogs" were the straight-winged F-84B/E/G Thunderjets (dubbed "Groundhogs") and the swept-wing F/RF-84F Thunderstreaks/Thunderflashes (AKA "Hyperhogs").  The follow-on RAC aircraft was to be a long range strike fighter designed primarily for nuclear attack on Cold War adversaries, with a secondary air-to-air combat capability.  As time and history would prove, the "Hog" label would not stick to the huge, new fighter-bomber, although it would be given other not-so-affectionate nicknames during its early "teething" years -- "Superhog," "Ultrahog," "Squat Bomber," "Lead Sled" and "Drop Forged by Republic Iron Works."   But the new Republic airplane would become highly respected by its pilots and greatly feared by its adversaries.  Today, only one name can adequately describe Republic's imposing F-105 Thunderchief - "the THUD."

The USAF/RAC letter agreement resulted in "Project AP-63," a company-funded proposal submitted to Air Force Headquarters in 1952 (Note: During WW II, "AP" meant "Army Proposal" at Republic, builder of the immortal P-47 Thunderbolt fighter.  RAC changed it to "Advanced Project" after the USAF became a separate armed service in September 1947).  The initial AP-63 design looked like a bulked up, swept-wing RF-84F Thunderflash with an internal bomb bay, to be powered by the then-untested Allison J-71 turbojet engine of 10,000 pounds thrust.  But while the Air Staff approved further RAC efforts on AP-63, it did not want an F-84 clone.  Republic began designing an all-new airplane and an Air Force letter contract for 199 aircraft was delivered to RAC in September 1952, with an initial operational capability (IOC) date in 1955 specified.

In March 1953, USAF accepted RAC's "AP-63-FBX" engineering proposal for the follow-on "Thunder" series member and ordered 37 XF-l05A "Thunderchiefs" and nine XRF-105A photo-reconnaisance aircraft, all powered by the upcoming Allison J71 engine.  The full scale aircraft mockup was approved in October of 1953, but delays in development of the Allison engine and other aspects of the program resulted in a program reduction to only 15 XF-105A test aircraft and then cancellation of the entire program by year's end.  Less than sixty days later, however, the program was resurrected and reoriented around the powerplant that would ultimately breath fiery life into the THUD...the mighty Pratt & Whitney J75 turbojet engine with (initially) 16,000 pounds of thrust w/o afterburner (the P&W YJ75-P-3).

On 22 Oct 1955, the first prototype Thunderchief, 54-0098 (one of the two YF-105As built), took to the air at Edwards AFB, California, with RAC test pilot Russell M. "Rusty" Roth at the stick for a 45-minute maiden flight in which the Thunderchief easily exceeded the speed of sound.  The YF-105A was a single-seat, single-engine aircraft with straight engine air intakes located at the roots of its mid fuselage - mounted wings. It had an internal weapons bay larger than the bomb bay of a World War II B-17, and four petal-type speed brakes around the engine exhaust at the extreme rear of its fuselage. The aircraft performed well during the early test flights and reached a top speed of Mach 1.2 -- all on a "temporary" P&W J57-P-25 engine with 10,000 pounds thrust sans afterburner (the YJ75s were not yet available).  YF-105A 54-0098 was lost two months later on 16 Dec 1955, when its right main landing gear extended during a 5.6 G turn at over 520 knots at 10,000 feet altitude.  A pitch-up of 9 G followed, then a negative 2 G pitch-down before the pilot could recover the THUD.  54-0098 was "totaled" after a wheels-up crash landing back at Edwards.  The second J57-powered YF-105A, 54-0099, soldiered on in flight testing after its first flight (35 minutes duration) on 28 Jan 1956.  It was used to complete testing at Edwards of both "bluff" and streamlined dummy "special devices" dropped from its 17-foot long bomb bay.

It was soon apparent to USAF and RAC engineers (as a result of Convair's F-102 experience with the NACA "area rule" or "coke bottle" fuselage shape) that the Thunderchief could reach even greater maximum speed with a totally redesigned fuselage.  The four follow-on YF-105B test aircraft were modified to include an area-ruled "wasp waist" or "coke bottle" fuselage, along with redesigned engine inlets angled forward (another NACA design) to provide greater airflow to the larger, hungrier P&W J75 engine and a taller, broader tail fin for increased supersonic stability.  As an added benefit, the larger rear fuselage area also allowed more internal fuel for greater range.

The first of four J75-powered YF-105Bs (F-105B-1RE 54-0100) flew at Edwards on 26 May 1956, piloted by RAC test pilot Henry G. "Hank" Baird, Jr.  But it was not a good beginning -- at the end of the one-hour test flight, the aircraft's nose gear refused to extend for landing and Baird had to make a gear-up belly landing on the Muroc Lake salt bed.  Although relatively undamaged by its belly landing, 54-0100 was broken beyond repair when the crane operator dropped it and broke its back while lifting it onto the flatbed trailer!  Despite the incident, on 19 Jun 1956 HQ USAF officially bestowed the Thunderchief name to the next in Republic's "Thunder" series.

On 30 Jan 1957, YF-105B #2 (F-105B-1RE 54-0101) ingloriously ended its maiden flight when its main gear refused to extend on landing approach at Edwards -- the auxiliary engine air inlets in the main gear wheel wells, feeding the hungry J75 engine at low airspeed and above 85% RPM, had somehow opened with the gear retracted, causing enough vacuum in the wheel wells to keep the gear up!  Repaired and ferried to the Air Proving Ground Center (APGC) at Eglin AFB, Florida, 54-0101 departed for cold weather testing at Ladd AFB in Alaska on 07 Feb 58.  By 21 Feb 1958, five flights had been completed in Alaska, but the cold weather testing was delayed by the non-availability of cold (-40 degree!) weather.  During a demonstration fly-by at Ladd in military power, 54-0101 apparently exceeded Mach 1 at 2500 feet altitude and shattered several windows in nearby Fairbanks!  But 54-0101 would only last until 02 May 1958 -- based back at the APGC, its pilot ejected over the Gulf of Mexico because of an explosion in the aft section and subsequent loss of control (a portent of the Thunderchief's immediate future).  The accident occurred while rehearsing as part of a 4-ship flight for a firepower demonstration planned for the week of 6 May 1958 at Eglin.  YF-105Bs 54-0102 and 54-0103 (both F-105B-1REs) continued flight testing at the APGC and back at Edwards.  Within three weeks, the area rule concept and the more powerful J75 engine proved their worth by enabling these "Dash-1" F-105Bs to reach Mach 2.12.  They were soon followed on the RAC Farmingdale production line by 75 production-standard F-105Bs, each featuring a 20MM M61 "Vulcan" cannon with six barrels, a  retractable air refueling probe, and integrated tape instruments in the cockpit.  Each F-105 also had a radar reflector installed on its nose gear, since the Edwards testing showed the Thunderchief had a very low nose-on RCS (radar cross section) with its gear extended. This early "stealth" quality was not considered a benefit -- the low gear-down RCS detracted from ground-controlled approaches for landing!  The radar reflector prompted later stories of a "nose gear sensor" that prevented THUDs from taking off until near the overrun at the end of the runway.  This infamous "gravel sniffer" would detect the gravel in the overrun and then allow the aircraft to fly.  THUD pilots claimed to counter the RAC engineers by installing a small bag of sand in the nose gear well with a long string to the cockpit:  "When you felt you were going fast enough, you pulled the string to dump the sand on the sniffer.  Then the airplane thought it was in the overrun and took off..."

In a ceremony at Republic's plant in Farmingdale, TAC's General Weyland accepted the first production F-105B-6RE (54-0111, the only "Dash 6" produced) for USAF operation on 27 May 1958, two years after the YF-105B's maiden flight and three years later than originally planned by the Air Force!  After a ferry flight to the APGC at Eglin, 54-0111 would shortly suffer a landing "incident" on 29 May 1958...  main wheel brake failure after the drag 'chute failed to deploy on landing after a test flight.  This resulted in the aircraft departing the runway, plowing through the loose Florida panhandle sand, and hitting a drainage culvert.  In turn, the culvert sheared the nose gear and right main gear, and damaged the right wing tip.  The fact that an acceptable anti-skid system had not yet been developed for the F-105 fleet was suspected as the cause of the thrilling ride taken by the APGC pilot, but later analysis of the aircraft revealed an ATM failure (see Electrical and Hydraulics, below) that caused the loss of utility hydraulic system pressure for the main brakes. F-105B 54-0111 was repaired and back on flight status by 20 Jun 1958.

Three of the initial batch of production F-105Bs (54-0105, 54-0108, and 54-0112) were completed as photo-recon RF-105B-1REs (later designated JF-105B-1REs), with faired nose bulges for the tactical WS-306L tactical camera system.  When the photo-recon variant was canceled by HQ Air Force, the three JF-105Bs served out their lives as RAC test aircraft at Farmingdale and Edwards with skinned-over camera ports.

The 355th Tactical Fighter Squadron (TFS) of the 4th Tactical Fighter Wing (TFW) at Seymour Johnson AFB, North Carolina, was the first TAC unit to receive F-105s (the "Dash 6" 54-0111 and F-105B-5s/-10s ) and participated in Category II (conventional weapons) testing while TDY at the APGC at Eglin.  The 355th TFS thus became the world's first unit equipped exclusively with Mach 2.0 strike aircraft, but -- because of maintenance difficulties with Thunderchief electronics, RAC production slippages, and a shortage of spare parts -- the squadron didn't become fully operational with the F-105B until late 1960. 

 In spite of this, the F-105B became the first aircraft in USAF history to complete its first year of Air Force service without a "major" accident.  (But RAC test flights out of Farmingdale and Grumman's Calverton facility on Long Island were another matter.  For instance, F-105B-10RE 57-5777 was lost during its third "production flight" on 11 Oct 1958.  During climb out from Republic Airport with the gear handle up, the RAC civilian pilot felt a "positive" jolt accompanied by a yaw, flickering of the R/H main gear light, and primary flight control hydraulic system 2 failure.  He reduced power and extended the speed brakes -- the utility hydraulic system then also went to zero PSI!  A diverted F-86 pilot reported the R/H main gear extended and "cocked" from normal, so the RAC pilot decided to abandon the THUD in lieu of trying an emergency landing at Grumman's Calverton facility with the apparently unsupported right gear.  The pilot ejected OK at 10,000 feet and was immediately plucked from the water, while the THUD splashed about three miles north of Riverhead, NY.  The right gear uplock mechanism was suspected as the culprit, and damage in the R/H wheel well could have damaged the Primary 2 and Utility hydraulic systems...)

Despite the  Thunderchief's large size and weight, the elite USAF Thunderbirds demonstration team even flew THUDs for a while, using F-105B-15REs 57-5782, 57-5787, 57-5790, 57-5793, 57-5797, 57-5798, 57-5801, 57-5802, and 57-5814.  The last of these nine specially-modified F-105Bs was delivered on 16 Apr 16, 1964, just ten days before the first Thunderbird public performance with the new planes.  Only six Thunderbird performances were flown with the Thunderchief during the 1964 air show season -- but after a fatal accident on 09 May 1964 involving the in-flight breakup of 57-5801 at Hamilton AFB, CA , the team returned to the trusty North American F-100C Super Sabre as its demonstration aircraft:

"Washington -- Thirty-eight B models of the Republic F-105 supersonic fighter grounded last May probably will not be returned to operational service until sometime next year following a major structural modification program.  B models were grounded May 8 when one of the aircraft disintegrated during a vertical turn maneuver by the Thunderbirds USAF precision flying team.  Fix involves a major strengthening of fuselage station 350 aft of the cockpit and along the aircraft's spine.  Following the grounding, the Thunderbirds did not fly again until September, when the group switched back to the earlier North American F-100." (Aviation Week, December 14, 1964)

Under USAF Project FAST WIND, on 11 Dec 1959 BGen Joseph H. Moore (Commander of the 4th TFW ) set a world 100-kilometer closed course speed record of 1,216.48 MPH, flying F-105B-20RE 57-5812 at 38,000 feet over Edwards AFB.  General Moore had completed the 62 mile-long course in a little over three minutes!

By 31 Mar 1960, TAC had received 56 F-105Bs, none of which were fully operational on that date.  By the end of the year, the 4th TFW at Seymour Johnson (344th, 336th, and 355th TFS) had received most of the 75 F-105Bs built, becoming the first Air Force wing to be totally equipped with Mach 2 strike aircraft.  But the 4th would become the only "regular" Air Force combat unit to fly F-105Bs -- by April 1964, they were replaced by more capable, all weather F-105Ds.  The F-105B Thunderchief served on with the Air Force Reserve (the 508th TFW at Hill AFB, Utah) and the New Jersey Air National Guard (177th TFG and 108th TFW) until 1981.  The production block numbers and serial numbers of the 75 F-105Bs built by Republic were:

In 1958, RAC proposed an "F-105C" two-seat training version, featuring a unique long bubble canopy covering both cockpits.  The Air Force opted, however, for the RAC- proposed "F-105E" two-seat all-weather attack version.  HQ USAF canceled further work on the "F-105E" initiative in 1959.

Probably the most famous THUD version was the single-seat F-105D, which first flew on June 9, 1959.  Equipped with better avionics and instrumentation than the B-model, the F-105D provided true all-weather attack capabilities.  Take-off performance was also increased with a water injection system for the J75 that boosted take-off thrust by 2,000 lbs (J75-P19-W).  RAC produced 612 "D-models" for the USAF during the 1959, 1960, 1961 and 1962 production contract years -- all were brought up to "Dash-25" standards under USAF Project LOOK ALIKE by the end of 1963. 

Project LOOK ALIKE was originally developed by the F-105 System Program Director in January 1962, with the objective of standardizing all F-105Ds to a single ("-25") configuration.  The major work was originally planned over one or more years during normal maintenance cycles. The project was divided into two Phases: Phase I, where safety of flight modifications were made, and Phase II, where the fleet was modernized and its combat capability enhanced.  In May 1963, the Air Force ordered the most extensive and operationally significant modification, installation of a dual in-flight refueling capability (a "flying boom" slipway and receptacle in addition to the RAC designed "probe and drogue" system).  This was a major structural modification to the nose of each aircraft that took about 2000 hours per aircraft.  The decision to incorporate this modification into the program extended the completion of LOOK ALIKE until May 1964.

Despite the successful completion of LOOK ALIKE, the F-105 was not as safe as the Air Force wanted it to be.  During the first four months of 1964, twelve F-105s were lost in major accidents due to engine failures, fuel leaks, and malfunctions in the fuel venting systems :

"Los Angeles -- Three Republic F-105 crashes - including one which killed a member of USAF's Thunderbirds - were being investigated last week.  A 40-member Air Force investigating team is probing the May 9 crash which killed Capt. Eugene J. Devlin during a routine six-aircraft Thunderbird flight at Hamilton AFB, Calif.  An eye witness at Hamilton said Devlin was on the left of the three-plane first element, which had just completed a low pass over the field.  Then, as they rose in a vertical climb, when Devlin's aircraft was in about a 45-degree attitude traveling about 300 kt. it broke in half and blew up.  The second crash occurred May 13 when a F-105D experienced a power failure on takeoff at Nellis AFB in Las Vegas, and plowed into several homes killing the pilot and four persons on the ground.  The third F-105 crash occurred after a power failure May 13 about 230 mi. southeast of Okinawa.  The pilot ejected and was rescued by a Navy ship." (Aviation Week, May 18, 1964)

"Los Angeles -- Air Force has launched an intensive aircraft-by-aircraft inspection of its Republic F-105 fleet as a result of four recent crashes which have killed two pilots and four persons on the ground.  The fourth crash occurred May 14 over Wendover, Utah, after the pilot experienced a cockpit fire warning.  The fire was verified by his wingman and pilot parachuted to safety." (Aviation Week, May 25, 1964)

"New York -- Crash of a fifth Republic F-105 last week -- after it has been removed from restricted flight status following a complete inspection -- suggested the Air Force will probably re-inspect all F-105s cleared so far....  The June 1 crash occurred 17 mi. southwest of McConnell AFB, Wichita Kansas, when Capt. Billy Sparks parachuted to safety after reporting a fire." (Aviation Week, June 15, 1964)

"New York -- USAF has found a correlation between high fuel consumption and recent accidents.... A sticking fuel pump float that has failed to shut off fuel flow.... resulted in pumping of excess fuel out of the venting system.  Ignition of the the vented fuel during high power operation is a possibility."  (Aviation Week, June 15, 1964)

At the time, the cause(s) of these accidents were not readily apparent.  Therefore, TAC requested a test program (dubbed "Category X Test") to seek out and fix the problems.  Air Force Chief of Staff General Curtis E. LeMay gave the test top priority, and the Category X testers went over five F-105Ds in minute detail.  After simple but sensitive test instruments were installed, each plane was taken out for a high speed taxi test.  When the results of those tests were known, test pilots put the aircraft through a series of increasingly difficult test  flights. The testers had 90 days to complete the program, but it took only sixty, and 500 flying hours were accumulated.  The Category X Test resulted in major Class IV modification programs to the Thunderchief, nicknamed "Safety Pack I and II," accomplished on the F-105 fleet by 30 June 1965 and 30 May 1966, respectively.  The modifications provided major improvements in the basic aircraft fuel system, upgraded the internal fuel and hydraulic plumbing, and incorporated provisions for increased ventilation and cooling in the engine shroud area (including a distinctive air scoop on each side of the aft section for increased "hot" section cooling).

On 10 Jan 1964, the final F-105D built, "dash-31" 62-4411, was delivered to the 23rd TFW "Flying Tigers" at McConnell AFB, KS.  Production block numbers and serial numbers of the 610 F-105Ds built were:

     * ALL BROUGHT UP TO "DASH-25" SPECIFICATIONS UNDER PROJECT LOOK-ALIKE

The distinctive THUD two-seater, the F-105F, first took to the air on 11 Jun 1963, reaching a top airspeed of Mach 1.15.  Originally contracted as F-105Ds, before they could be built at RAC Farmingdale the USAF ordered they be delivered as two-seaters -- no Thunderchiefs were actually procured as F-105Fs from the outset!  Service introduction was in December 1963, with F-105Fs delivered to the 4520th Combat Crew Training Wing, Nellis AFB, Nevada, and to the 4th TFW at Seymour-Johnson, where it flew alongside already-delivered F-105Ds.  A total of 143 F-105Fs were produced by RAC during the 1962 and 1963 production contract years.  A modified D, the F-model's fuselage was stretched about 31 inches to accommodate the second cockpit and its tail fin extended in height and chord.  The delivery of the last F-105F to Brookley AFB, Alabama, on 9 Jan 1965 marked the end of Thunderchief production. The closing down of Thunderchief production also marked the end of Republic Aviation Corporation as a manufacturer of fighter aircraft.

F-105Fs were originally intended as multi-mission trainer/combat aircraft to be assigned to squadrons flying the single-seat F-105D.  But the most glorious role for the F-105F was the hazardous Wild Weasel mission in Southeast Asia (SEA)  -- searching out and destroying enemy radar, surface-to-air missile (SAM), and AAA sites.  By the summer of 1965, SA-2 SAMs were being installed and used by the North Vietnamese (NVN) around Hanoi against USAF/USN strike mission aircraft.  Initially, specially-modified "Wild Weasel" F-100F Super Sabres were used to search out and destroy the NVN radar, SAM, and AAA sites.  The Wild Weasel F-100Fs would usually accompany conventional strike "packages" and suppress or destroy the radar and SAM sites, thereby increasing the survivability of the strike force as it penetrated heavily defended areas.  But the F-100s flew slower in the mission packages than the bomb-carrying THUDs, slowing each package and increasing its vulnerability.  On 8 Jan 1966, the USAF ordered the "EF-105F" (an unofficial designation) as the follow-on Wild Weasel (Project WILD WEASEL III).  The first modified "EF-105F" (62-4416) flew on 15 Jan 1966, and test and development work was completed in May. Initial "EF-105F" pilots and electronic warfare officers came from the F-100F Wild Weasel training detachment at Eglin AFB. The first Wild Weasel F-105Fs left for Southeast Asia in June 1966, and by midyear 11 "EF-105Fs" and 25 crews were killing SAM and radar sites with the new AGM-45 Shrike anti-radiation missile (ARM) that homed in on and tracked down emitter beams.  By 11 Jul 1966, all the F-100F Wild Weasels were withdrawn from anti-SAM operations.  Eventually, 86 "EF-105Fs" were modified and dedicated to the Wild Weasel role from air bases in Thailand. 

Many targets in the North had to be attacked at night to reduce losses.  By March 1967, the first four of eventually 13 "EF-105Fs" were modified under the NORTHSCOPE program (later called "Commando Nail") with an improved R-14A NASARR radar with higher resolution which made it possible to achieve sharper target definition on the rear cockpit scope.  In addition, the pilot's weapons release switch was modified to enable the rear seat pilot to control bomb release and special cabin lighting provided in both cockpits.  Flown by eight select crews (selected by PACAF Commander Gen John Ryan and thus known as the "Ryan's Raiders"), Commando Nail F-105Fs of the 44th TFS at Korat AB flew the first of numerous hazardous all-weather low-level night bombing missions on 26 Apr 1967, bombing the most difficult targets in NVN.  Although their F-105Fs had an enhanced terrain-following radar and radar jamming capabilities, the 44th TFS Commando Nail mission required the highest levels of skill and courage.  Three Commando Nail aircraft were lost in action by 4 Oct 1967, and by the end of the year, the Commando Nail F-105Fs were returned to their original configurations and brought into the Wild Weasel III program.  Commando Nail F-105Fs were 62-4419, -4429 (lost 15 May 1967), 63-8263, -8269 (lost 12 May 1967), -8274, -8275, -8276, -8277, -8278, -8293, -8312, -8346 (lost 4 Oct 1967), and -8353.

In late 1967, thirteen of the "EF-105Fs" were converted into "Combat MARTIN" communications jammers to block radio communications between enemy MiGs and NVN ground control intercept (GCI) controllers.  A Hallicrafters QRC-128 VHF jamming emitter replaced the rear seat pilot and cockpit equipment ("There was a big square white antenna up behind da bear pit and the rear seater obviously called 'Colonel  Computer' ").  Operated by the 355th TFW, MARTIN jamming made interceptions more difficult for the NVN MiG pilots, who relied on GCI instructions to intercept and engage US aircraft.  The 355th MARTINs also carried underwing jamming pods and retained full weapons delivery capabilities.  Only one Combat Martin, F-105F 63-8337, was lost to enemy ground fire on 15 Apr 1968.  When the 355th TFW stood down in November 1970, the MARTINs were returned to the Wild Weasel configuration.

Sixty-one (some sources say 55) of the 86 "EF-105Fs" were later specially modified and officially designated as F-105Gs for the Wild Weasel role.  Installation of the AN/ALR-31 Radar Homing and Warning (RHAW) set distinguished the F-105G from the "EF-105F," and required wingtip sensors that displaced the navigation lights, which were moved further forward on each wing leading edge.  The F-105G also had two long, cylindrical blisters along the sides of the lower fuselage, housing internally-mounted Westinghouse AN/ALQ-105 electronic countermeasures jamming transmitters.  This freed up the outer underwing pylons (used on the "EF-105F" to carry such noise jamming pods such as the Hughes ALQ-71 or General Electric ALQ-87) for additional ordnance on the F-105G (such as more Shrike ARMs).  Fourteen of the F-105Gs were further modified to carry and launch the 1,350lb General Dynamics AGM-78A/B Standard ARM. This ARM had a higher performance, longer range, and a larger warhead that that of the Shrike, which was at that time giving indifferent results in SEA operations.  Because of these modifications, the F-105G had slightly less internal fuel capacity than the F model (1051 gallons versus 1160 gallons for the F-105F).  Unlike the single-seat F-105Ds which were withdrawn from SEA in 1970, F-105Gs remained in SEA operations until the end of US involvement in 1975.

F-105F production block numbers and serials numbers were:

The THUD proved to be a formidable opponent, whether in the air-to-air realm or in air-to-ground mode.  When engaged in a dogfight, the THUD's Vulcan cannon could fire with deadly accuracy at a rate of 6,600 rounds per minute.  As a fighter-bomber, the THUD could carry a maximum bomb load of 12,000 pounds.  Its internal bomb bay could hold a 2,000-pound conventional bomb (or a 3,400-pound "special device") or an additional 390 gallon fuel tank for greater combat range.  The THUD's "dry" wing (no fuel tanks there) and strong wing spar proved valuable in close-in combat action in Southeast Asia operations. 

Based on its solid performance and its heroic aircrews during the Vietnam War, the THUD attained a legendary combat reputation.  Over 20,000 combat missions were flown by Thunderchiefs in Vietnam.  The THUD was the only Air Force "Century Series" fighter to score air-to-air combat victories during the Vietnam War, accounting for 27.5 MiG kills (2.5 by F-model crews).  Although flying a large, heavy, relatively sluggish aircraft, two of the 12 Air Force Medal of Honor winners in Vietnam were THUD pilots Captain Merlyn Dethlefsen and Major Leo Thorsness.  Over 75 percent of the bombs dropped over North Vietnam in operations Rolling Thunder and Linebacker I were carried by THUDs.  The price paid on these THUD sorties in Viet Nam was relatively high -- almost half of the F-105s built (382 of 833 aircraft) were lost in combat or in operational accidents during the conflict, with the loss of 156 valiant American airmen:

The last SEA strike mission of the F-105D was on 6 Oct 1970.  However, Wild Weasel THUDs remained on hand for combat, participating in operation"Freedom Train" in the spring of 1972, in the more-intense "Linebacker I," and finally in "Linebacker II" during the Christmas season late that year.  The bombing was much less restrained and much more effective than before, with Linebacker II finally pushing the North Vietnamese to the bargaining table in Paris.

Indicative of the THUD's durability, the "highest time" THUD retired at Hill AFB, Utah, with 6,730.5 flying hours (it's now on permanent display there).  The 419th TFW at Hill made the last operational THUD flight in February 1984.  Airmen will long tell of the brave exploits of the THUD and her pilots...
 

Colors And Markings
 

COLORS AND MARKINGS 1

COLORS AND MARKINGS 2

Specifications

Armament: F-105D/F -- One 20MM M61A1 rotary cannon (General Electric's 6-barrelled "Gatling Gun" design, capable of expending 6,600 rounds per minute at full spin) with 1028 rounds stored in a nose ammo drum above the gun...  this was good for a little over 10 seconds of cannon fire, with spent cartridge casings returned to the drum to maintain aircraft CG.

Up to 12,000 pounds of conventional ordinance could be carried on external multiple ejection racks (MER) -- four on the wing pylons and one on the fuselage centerline pylon (attached to the closed bomb bay doors).  Typical conventional weapon loads included six 750-pound bombs or five 1000-pound bombs on the MERs; or one 3000-pound bomb on each outboard wing pylon; or 9 LAU-3/A or LAU-18/A rocket pods or napalm canisters; or 2 Martin AGM-12B/12C Bullpup air-to-surface missiles; or four AIM-9B Sidewinder infrared homing missiles (air intercept role) on the outboard wing pylons.

Up to 8,000 pounds of nuclear ordnance could be hauled internally and externally:  a B28 or a B43 "special device" or "shape" (generally with a retarding drogue 'chute) in the 20' long internal bomb bay; or on the centerline pylon attached to the bomb bay doors (B57 or B61, aerodynamic profile); or on the inboard wing pylons (B61, aerodynamic profile).  Vertically above and extending into the internal bomb bay was the THUD's unique bomb "displacing gear" or "ram" -- essentially a large-bore vertical piston powered by compressed air -- to push the weapon bolted to it into and through the rock-hard 1200 MPH air stream during the bomb run.  Reportedly, the ram could also "displace" the shape through battle-damaged, "frozen" bomb bay doors if necessary!  Early in the design of the THUD, both Republic and the Air Force were concerned about potential problems of delivering the special devices at supersonic speeds.  Earlier USAF experience with Boeing B-47 StratoJets at high subsonic Mach numbers resulted in some released bombs not dropping through the slipstream under the bomb bay, striking the bay interior due to the high turbulence and the dynamic pressures in the bay at those speeds.  Because of this, the F-105's unique weapon delivery system was based on pushing the weapon out of the bomb bay with the large air piston ram.  Using 250 ±25 PSI compressed air and a 30-inch stroke, the ram imparted a full velocity of 32 fps to the "shape," allowing the weapon to punch through the adverse air flow in the bomb bay and under the aircraft.  As the aircraft was completing its design, however, a special weapon with a "blunt shape" casing ("TX-28") was especially tailored for use in the THUD.  Early drop tests with one of the prototype F-105s (YF-105A 54-0098) showed this shape almost totally stable over a wide range of release angles and velocities -- even in adverse air flow and high dynamic pressure -- and the air-powered weapon ejection ram was not really needed.

THUD nuclear strike configuration while on "Victor Alert" status at Bitburg generally consisted of the "special device" shear-bolted to the bottom of the bomb bay ram, a centerline-mounted 650 gallon external fuel tank mounted on the closed bomb bay doors, and two 450 gallon underwing tanks -- all these external tanks were to be emptied ASAP in the mission and then jettisoned for a "clean wing" configuration for the close-in, down low, Mach 1.2 dash to the target ("toss bomb" or "over-the-shoulder" deliveries were contemplated, and the low nose-on RCS added stealthy assurance to the mission).   On Victor Alert duty, a pilot-fired cartridge starter would be used for starting up the J75 if the "balloon went up" -- there would be no time to position, hook up and start the external, wheeled "ploosh" unit normally used on the flight line.

Fuel: F-105D/F -- Internal fuel (JP-4) load of 1149 gallons (US) (1160 gallons for the F-105F) in seven fuselage tanks (including 14 usable gallons in internal fuel lines).  The 20 foot long bomb bay could also accommodate a 390 gallon (US) auxiliary tank (non-jettisionable, hard-bolted to the bomb shackles on the "special stores" ram) to supplement the internal fuel load.  This could be further boosted by a 450 or 650 gallon (US) external tank on the fuselage centerline (the tank's pylon attached to the bomb bay doors) plus a 450 gallon (US) tank on each inboard wing pylon, bringing total maximum JP-4 fuel capacity to 3099 US gallons (including 11 gallons in the external tank lines).  Both the centerline tank and wing tanks (and their pylons) could be jettisoned at crew command with explosive pylon cartridges ("carts").

Dimensions:  F-105D -- Wingspan 34 feet 11 inches, length 64 feet 3 inches, height 19 feet 8 inches, wing area 385 square feet.  F-105F -- Wingspan 34 feet 11 1/4 inches, length 69 feet 7 1/3 inches, height 20 feet 2 inches, wing area 385 square feet.

Weights:  F-105D -- 27,500 pounds empty, 35,637 pounds combat (clean), 48,400 pounds gross, 52,546 pounds maximum takeoff weight.  F-105F -- 40,073 pounds combat (clean), 54,027 pounds maximum takeoff.

Engine:  One Pratt & Whitney J75-P-19W turbojet rated at 16,100 lb static thrust (ST) (sea level, w/o  afterburner (AB) or water injection), 24,500 lb ST with AB, and 26,500 lb ST with both AB and water injection.  The J75 engine was a continuous-flow gas turbine with a 3-stage set of turbine wheels (an 8-stage low pressure compressor at the front, then a 7-stage high pressure compressor and a "hot" turbine section aft of  8 can annular combustion chambers), all  joined to an afterburner (AB) section with its 2-position, 4-petal exhaust nozzle.  The 1st stage high pressure compressor rotor was connected to, and driven by, the 1st stage rotor of the "hot" turbine section by a hollow shaft.  Within that hollow shaft was a second shaft from the 2nd- and 3rd stage "hot" turbine wheels, driving the low pressure rotor wheels at the very front of the engine.  The J75 was normally started with low pressure compressed air supplied by an external "ploosh unit," but could also use a pilot-fired, coffee-can-sized start cartridge to get the engine RPM up to idle and light-off within 10 seconds.  The start cart breech was located at the mid/lower left quadrant of the engine (access panel FF21, just to the rear of the single point ground fueling point at access panel FF7).  The burning rocket propellant in the start cart turned a mini-turbine that twisted a shaft geared to the J75's low pressure rotor wheels (but those cart starts had a bad habit of breaking that connecting shaft on cold morning starts at Bitburg and Spangdahlum...).  The P&W J75 is still in production and use today for electrical "cogeneration" and backup electric power generation!

Variable Air Inlet (VAI) System:  An integral design feature of the THUD, the VAI varied the interior geometry of the THUD's distinctive "reverse" air inlets to match the J75's demand for maximum efficiency throughout the wide speed range of the aircraft.  Operating with a boundary layer fence next to the fuselage in front of each intake, the VAI system had movable contoured plugs located in the air inlet in each wing, and inlet bleed air doors on each side of the fuselage, below and behind the wing TE.  The inlet plugs and bleed air doors were positioned by hydromechanically-operated screw jacks, using Utility hydraulic system pressure.  A central air data computer (CADC) controlled movement of the inlet plugs fore and aft (varying the size of the inlet area) and the bleed air doors (dumping excess air from the inlet) to match the real-time performance variables of the THUD.  Powered by the 115V secondary AC bus, the CADC relied on immediate and basic information about the atmosphere through which the THUD flew -- indicated airspeed (Mach number), true airspeed, aircraft altitude, outside air temperature and density, and angle of attack (AOA).  When selected for automatic operation, during takeoff, subsonic acceleration, climb, or cruise the plugs remained fixed aft with the bleed air doors closed.  On increasing air speed, at Mach 1.05 (± .05), the VAI system became energized.  Above this cut-in speed, the fuselage bleed air doors could automatically open to dump inlet air, depending on the current Mach number and temperature signals from the CADC.  The plugs remained full aft until Mach 1.5, when they were moved forward as scheduled by the CADC.  The inlet plugs reached their full forward position at approximately Mach 1.92.  Automatic operation required power from the DC primary, the AC primary and secondary buses, and the Utility hydraulic system.  In an in-flight emergency, the inlet plugs locked in their current position and the fuselage bleed air doors opened.  Also, auxiliary air inlets with fixed screens ("sucker doors") were located on the inboard side of each main landing gear wheel well.  These inlets improved the J75's performance on takeoff and landing by allowing additional intake air into the J75's main air duct.  Upon landing gear retraction, these auxiliary air inlets were closed and locked mechanically by the inboard main landing gear doors.

Electrical and Hydraulic Systems :  Each THUD was equipped with an engine-driven 28 volt, 400 ampere DC generator and a 100 amphere-hour battery for standby DC power (a fully-charged battery could supply the primary aircraft DC power bus load for 1.4 hours).  An external AC/DC power receptacle was provided low on the aircraft (access panel FF106) for use of an external MD-3 or MD-60 power cart.  Internal aircraft AC power was provided through a two-bus ("Primary" and "Secondary") system by a three-phase, 115/200 volt, 400 cycle generator driven by an air turbine motor (ATM) located in the left upper nose of the THUD, just forward of the cockpit (access door FF76).  Switched on from the cockpit, the ATM was driven by hot ducted compressor air (pressure regulated) from the 7th stage of the high compressor section of the J75.  Until the ATM was started by the pilot or after loss of the AC generator in flight, a "standby" DC-to-AC inverter would power the AC primary bus.  In addition to the AC generator, the ATM also drove a 3000 PSI "Utility" system hydraulic pump for operation of the landing gear (nose and main struts), LE flaps, speed brakes, the IFR refueling probe and boom slipway, bomb bay doors, nose wheel steering, main wheel brakes, the VAI system, M61A1 gun drive, and the J75 water injection pump.  Flight surfaces (stabilator, rudder, wing ailerons and spoilers) were powered by two 3000 PSI pumps driven by the J75 engine.  Each flight surface hydraulic system (Primary 1 for the left side and Primary 2 for the right side) powered one side of each flight surface hydraulic actuator and the cockpit control stick boost.  The Primary 1 hydraulic system also provided power for the AF/A42G-8 automatic flight control system (AFCS) for operation of the Thud autopilot, toss bomb computer, Doppler navigator, etc.  Reservoirs for the Primary 1 and Primary 2 hydraulic systems were located in the left and right wheel wells, respectively.  For ground maintenance, access for connection of the 4000lb MJ-5 hydraulic "mule" to the hydraulic systems was at access panel FF6 on the lower right side of the fuselage nose.  In flight, loss of the J75-powered primary flight control systems or an engine flameout could be countered by the pilot extending a belly-mounted Ram Air Turbine (RAT) which used a ram air-driven pump and transfer valving to provide limited hydraulic pressure to the Primary 1 side of the flight surface actuators, using the Utility system's reservoir hydraulic fluid.  But damage to the Primary 1 flight control system with fluid loss could then cause quick depletion of the Utility hydraulic system's fluid supply!

Ejection Seat (F105D/F):  Upward ejection, catapult type, designed to eject the pilot clear of the aircraft in an emergency.  The seat incorporated an armor plated headrest, provisions for electrical adjustment of seat height, adjustable armrests, an automatic lap belt release system with accommodations for automatic parachute, a shoulder harness with multi-directional inertia reel, canopy jettison and seat ejection controls, and a quick disconnect for the pilot's personal leads.  An explosive seat catapult charge, attached to the rear of the seat, supplied the propelling force to eject the seat during an emergency (provision was made to replace the explosive seat catapult charge with a rocket type ejection charge).  The seat catapult charge was fired by an initiator which developed high pneumatic pressure directed to actuate the catapult firing mechanism.  The seat was safetied for ground operation by a pin installed in the right leg brace.  The ejection controls were designed to jettison the canopy before seat ejection.  The seat bucket accommodated the MC-1 seat cushion, and an integrated oxygen system permitted the use of the Type MD-1 (modified type A-1) survival kit container. .

Communications, Identification, and Navigation (CIN) Systems:  The F105 Thunderchief was equipped with the AN/ASG-19 "Thunderstick" system designed to meet an all-weather operations requirement specified in USAF General Operational Requirement (GOR) 49 (revised), November 1957.  AN/ASG-19 was designed around the NASARR (North American Search and Range Radar) R-14A all-purpose monopulse search and ranging radar, optimized for both air-to-ground and air-to-air modes and capable of performing both low-level and high-level missions.  The radar also incorporated a terrain guidance mode, permitting the pilot to let down through bad weather in unfamiliar territory or hug the ground in order to avoid detection -- critical to the delivery of nuclear ordnance.  The most critical Thunderstick component was the General Electric FC-5 automatic flight control system (AF/A42G-8 AFCS), which operated in conjunction with the R-14A NASARR radar to provide the Thunderchief with true all-weather weapons delivery capability.  The FC-5 system comprised a toss bomb computer (AKA Low Altitude Bombing System or LABS) for hands-off "AUTOSS" bomb deliveries, a gun sight for the M61A1 20MM cannon, the Doppler navigator, the air data computer, a missile launch computer, and an autopilot (with stability augmentation in roll, pitch, and yaw axes), all interacting with the NASARR R-14A radar. For precise long range navigation, the AN/ARN-85 or AN/ARN-92 long range navigation (LORAN C/D) and AN/APN-105/131/148 Doppler Track/Great Circle Course nav systems were installed as part of the AN/ASG-19 system. Other installed CIN systems included the AN/ARC-70 command radio with 1750 selectable frequencies (20 channels preset, 225.0 to 399.9 megacycles), AN/ARA-48 UHF ADF, AN/ARN-62 UHF TACAN nav set, AN/APX-37 identification radar for L-Band IFF/SIF, AN/APN-141 low altitude radar altimeter, and the AN/ARN-61 VHF instrument letdown system (ILS) for automated runway approaches to landings in near-0/0 weather.

 
Performance

Maximum (Ground) Speed:  F-105D: Maximum speed 1420 mph at 38,000 feet (Mach 2.12), 1372 mph at 36,000 feet, 1122 mph at 50,000 feet (absolute ceiling), 836 mph at sea level (Mach 1.27). Stalling speed 208 mph (clean).  F-105F: Maximum speed 1386 mph at 38,000 feet (Mach 2.1), 876 mph at sea level (Mach 1.33).

Initial Climb Rate:   F-105D:  34,500 feet per minute (clean; 39,350 pounds GW).

Service Ceiling:  F-105D/F: 32,100 feet (combat ceiling 48,500 feet and absolute ceiling 50,000 feet).

Combat Range:  F-105D: 778 miles (clean, no external tanks), with maximum range of 2208 miles with full external fuel and no inflight refuelling.  F-105F:  Combat radius 740 miles with eight 750-pound bombs.