F-105D Thunderstick II: Radar-Guided Precision Bombing

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Hi, I wrote a lot about this for some reason.
Introduction and History

Origins of the F-105

The F-105 was the premier fighter-bomber of the Vietnam War. Starting in 1952, Republic submitted their AP-63 proposal, which would then be approved by the US Air Force later that year and contracted as the F-105. The original design, looking much too like an RF-84F, and due to delays in engine procurement (it was to be powered by the Allison J71-A-7 engine), the program was canceled. Sixty days later, however, the program was resurrected as Republic now saw the Pratt & Whitney J75 as the ideal engine. Initially, the non-area-ruled YF-105A was powered by the J57-P-25 engine used on the F-100 and tested in 1955 due to delays with procuring the J75 engine that Republic needed.

In May of 1956, a new beast took to the skies: The F-105B. Featuring an area-ruled fuselage and the mighty J75 engine, the F-105B provided a staggering performance increase over the YF-105A. In full burner, the J75-P-5 provided a 7,000 lbf. increase over the J57’s maximum thrust. In fact, the J75 in military thrust provided roughly an equivalent amount of thrust to that of the J57 in full burner. From these changes, the aircraft went from a top speed of around 740 knots with the YF-105A to around 1100 knots with the F-105B. The aircraft also featured the MA-8 (E-34 Fire Control Radar) FCS. Later blocks would see the installation of a slightly more powerful J75-P-19 engine. A two-seater, the F-105C, was also proposed but refused due to budgetary constraints.

Thunderstick vs. Thunderstick II (Another History)

As if this was not enough, 1959 saw the acceptance of the definitive Thunderchief variant, the F-105D, which would be the primary variant used until its retirement from frontline service. One improvement was the introduction of the J75-P-19W, which provided water injection in order to increase take-off thrust (at the time this was the most powerful engine on any aircraft). The F-105D has both a higher Max T.O. weight and Max Landing weight when compared to the F-105B. However, the most important change was the introduction of the AN/ASG-19 Thunderstick FCS. This system provided the following to the F-105D:

  1. R-14 or R-14A Radar
  2. Improved AN/APN-131 Doppler Navigator

The Thunderstick FCS provided the F-105D with an array of radar functions to help in navigation and weapons delivery, such as:

For Navigation:

  1. Ground Mapping
  2. Terrain Avoidance and Contour Mapping
  3. Doppler Radar Fix

For Bombing:

  1. Visual Dive Toss (Radar or pressure (CADC) ranging)
  2. Visual Identification Point and Visual Target Identification Point (VIP/VTIP)
  3. Radar Identification Point and Radar Target Identification Point (BIP/BTIP)

While these upgrades turned the F-105 into an exemplary all-weather fighter bomber, this would not be the final upgrade proposed for the aircraft. In 1969, ten years after the F-105D took flight, Republic proposed the Thunderstick II (T-Stick II) avionics upgrade. Featuring an enlarged dorsal spine for avionics, the new FCS provided much improved navigational systems for greatly increased accuracy for bombing. T-Stick II provided the following for the F-105D (on top of existing systems for the AN/ASG-19):

  1. R-14K Radar
  2. Improved AN/APN-196 Doppler
  3. Improved AF/A42G(XK-1) Automatic Flight Control System (AFCS)
  4. AN/ARN-92V C/D LORAN
  5. AN/ASN-100 Gyro Compass Altitude Velocity Reference Set (GAVRS)
  6. Static discharge on the flight surfaces

Compared to the standard Thunderstick, T-Stick II provided the following improved capabilities for the F-105D:

For Navigation:

  1. Ground Mapping
  2. Terrain Avoidance and Contour Mapping
  3. Doppler/Inertial
  4. LORAN

For Bombing:

  1. Visual Dive Toss (Radar or pressure (CADC) ranging)
  2. Visual Identification Point and Visual Target Identification Point (VIP/VTIP)
  3. Radar Identification Point and Radar Target Identification Point (BIP/BTIP)
  4. Visual Target Radar Ranging (VTRR)
  5. Continuous Solution Bombing Mode
  6. LORAN
  7. Depressed Reticle Dive (DIVE)

Upon its original presentation in 1969, the upgrade proposal was met with mixed remarks, somewhat of a “one step forward, two steps back” solution. The concept of using radar to engage ground targets with precision in an all-weather environment was a great improvement to the existing FCS. Laser-guided weaponry with the same precision offered by T-Stick II would have required a large, bulky, and quite fragile system. However, there were two major issues with the proposal:

  1. The system used analog components, which would not have the same type of accuracy expected of digital weapon systems going into the A-7D/E and F-111D at that time.
  2. The Loran, despite being rate-aided by the doppler-inertial subsystem, would not enable the aircraft to maneuver in the case of a blind bombing run. The pilot could have to fly straight for up to 25 miles in order to get a correct bearing with the Loran. An integrated Loran could fix this issue.

Despite this, the system demonstrated its ability, providing seven times greater bombing accuracy, and a 50 ft. CEP (circular error probability) at a bombing altitude of 15,000 ft. Air-to-air detection would be increased by about 10%. Terrain avoidance and contour mapping accuracy were greatly improved as well. The system also provided greater scope accuracy and gave the pilot a more dynamic range in which he could acquire and track targets.

Nevertheless, the T-Stick II configuration entered limited production, with a total of 30 aircraft from various blocks (10, 15, and 20) being converted to this standard from 1969 to 1971. An additional aircraft was reserved as a spare. These aircraft initially found themselves in service with the 563rd TFS, 23rd TFW, in 1971 after the unit had left Vietnam in order to train more F-105 pilots stateside. Afterwards, these aircraft were transferred to the recently reactivated 457th TFS, 301st TFW in 1972. The unit saw service in NATO exercises, with T-Stick II aircraft being seen in Germany in 1977 during exercise Cornet Poker. These aircraft were finally retired from service in 1981. Five of the thirty aircraft survive to this day (60-0455, 60-0471, 60-0500, 61-0100, 61-0110). The spare (61-0159) also survives.

Specifications

Specifications (F-105D T-Stick II)

Republic stated that while the raised section should not increase the aircraft’s drag by any appreciable amount, the spine would offer an increase in directional stability.
Dimensions
Crew: 1 (Pilot)
Length: 64 ft. 5.3 in.
Wingspan: 34 ft. 11.2 in.
Height: 19 ft. 8.4 in.
Weight:

  • Empty: 26,855 lbs.
  • Basic: 27,233 lbs.
  • Design: 34,058 lbs.
  • Combat: 35,637 lbs.
  • Max Take-off: 52,838 lbs.
  • Max Landing: 51,038 lbs.

Fuel: 1135 (1160) gal. usable @ 7,377.5 (7,540) lbs. internal (additional 390 gal. and 2,535 lbs. when bomb bay tank is used) / 1350 or 1550 gal. usable @ 8,775 or 10,075 lbs. in wing and centerline drop tanks (Drop tanks are 450 gal., but a 650 gal. tank can be fitted to the centerline)
Powerplant: Pratt & Whitney J75-P-19W
Thrust @ SSL:

  • 14,300 lbf normal
  • 16,100 lbf military
  • 24,500 lbf max
  • 26,500 lbf take-off (1 minute)

Flight Performance
Speed:

  • Basic: 726 kt. @ 0 ft.
  • Combat: 726 kt. @ 0 ft.
  • Max: 1199 kt. @ 36,089

Stall speed: 180.6 kt. @ TOW
Climb rate:

  • 4650 fpm @ SL, MTOW, Military Power
  • 34,000 fpm @ SL, Combat Weight, Maximum Power

Combat Radius: 543 nmi. (676 w/ wing tanks)
Ferry Range: 1917 nmi.
Take-off run: 4270 ft.
Ceiling: 51,800 ft.

Stores
M61 w/ 1028 rnds

750 lb M117
3000 lb M118
Mk 82/83/84
Mk-28EX and Mk-28RE, Mk-43, Mk-57, Mk-61
M116A2, BLU-1/B, BLU-27 firebombs
AIM-9B/E Sidewinder
AGM-12B/C Bullpup
AGM-45A Shrike
LAU-3/A
LAU-18/A
LAU-32
LAU-59
AN/ALE-2

Avionics
AN/ASG-19 Fire Control System
R-14K Radar
AN/APN-196 Doppler
AN/ARN-92V C/D LORAN
AN/ASN-100 GAVRS
AN/ARN-62 TACAN
AN/APX-37 IFF/SIF
AN/ARN-61 Marker Beacon, Glide Slope, and Localizer
AN/ARW-73
AN/ARN-48 ADF
AN/ARC-70 Command Radio

Aircraft Images (10)










Technical Images (14)














Conclusion
The F-105D T-Stick II was an attempt by Republic Aviation to extend the service life of the aging F-105D by integrating a sophisticated FCS to the existing airframe. Unfortunately, it didn’t catch on, and new digital fire control systems were adopted instead on newer aircraft. In War Thunder, this aircraft would provide the player a Thunderchief capable of radar targeting and CCIP*, great for both air and ground battles.

Sources

T.O. 1F-105D-1 - F-105D/F/G Flight Manual - 19700909
T.O. 1F-105D-1 - F-105D/F/G Flight Manual - 19741231
T.O. 1F-105D-1-1 - F-105D Thunderstick II Supplemental Flight Manual - 19710301
F-105D-31 CS - 197104
F-105D-31 SAC - 197006
F-105 Thunderchief in Action - No. 17 (1974)
F-105 Thunderchief in Detail & Scale Vol. 08 (1982)
Osprey Air Vanguard 2 - Republic F-105 Thunderchief (2012)
Classic Warplanes - Republic F-105 Thunderchief (1992)
Walk Around F-105 Thunderchief - Walk Around Number 23 (2000)
Warpaint Series No. 38 - Republic F-105 Thunderchief (2012)
Modern Military Aircraft - Republic F-105 Thunderbolt ‘Thud’ (Squadron-Signal) (1986)
Aviation Week & Space Technology (January 20, 1969)
Joe Baugher - F-105D
Various online sources for images

*The Note

I don’t know why the F-105D we have in-game has CCIP. The standard F-105D manuals make no statement of it, while the T-Stick II manual has over a page dedicated to it. Furthermore, the standard F-105D instrument panel also doesn’t have anything for the CCIP, while, once again, the T-Stick II has a switch dedicated to it. If anyone could tell me more about this, please feel free to do so.

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