The F-15C was the next major single-seat version of the Eagle. Externally, it was virtually identical to the F-15A which preceded it, but internally there were a number of significant differences that made it a much more capable fighter aircraft.
The only external difference between the F-15A and the F-15C was the introduction on the F-15C of the capability of carrying FAST (Fuel And Sensor Tactical) packs attached to the side of the fuselage outside of each air intake. The tanks conform to the aerodynamic shape of the side of the fuselage, and when they are installed, there is very little adverse aerodynamic effect and very little degradation in performance. When the FAST packs are removed, the F-15C is externally indistinguishable from the F-15A, and the two variants can be distinguished only by a knowledge of their serial numbers. However, on the F-15C, the FAST packs are only very rarely actually taken off the aircraft. The FAST packs are now referred to as Conformal Fuel Tanks (CFTs).
Each FAST pack can carry an additional 849 US gallon of fuel. Alternatively, sensors such as reconnaissance cameras, infrared equipment, radar warning receivers and jammers, laser designation, and low-light TV cameras can be carried in place of some of the fuel in these packs. The FAST packs were first tested on an F-15B on July 27, 1974. They can be installed or removed in 15 minutes on the ground.
Even when the FAST packs are installed on the sides of the aircraft, the F-15C still retains the capability of carrying Sparrow or AMRAAM missiles on the lower corners of the fuselage. When the FAST packs are fitted, the four Sparrow missiles are mounted on their corners, and bombs or air-to-surface missiles weighing up to 4400 pounds can be carried as an alternative.
Although the FAST packs alone carry slightly less fuel than the normal three external fuel tanks, they permit the aircraft to be flown at considerably higher speeds. Maximum ferry range with the increased internal fuel capacity, the FAST packs, and three external drop tanks is 3450 miles.
From the start of production, the F-15C dispensed with the engine exhaust "turkey feathers" which covered the variable nozzles, greatly simplifying the maintainence. However, by the time of the appearance of the F-15C, these had been deleted in the field from most of the in-service F-15As as well, so the presence or absence of engine nozzle turkey feathers is not necessarily a reliable external indicator of whether a single-seat Eagle is an A or a C.
Internally, the F-15C differs from the F-15A in having additional wing leading and trailing edge tanks, and additional tanks in the central fuselage, bringing total internal fuel capacity to 2070 US gallons (not counting the fuel in the FAST packs). The additional weight of fuel raised the gross weight of the F-15C to over 68,000 pounds. Consequently, tires, wheels, and brakes had to be strengthened to cope with this increased weight.
As compared to the F-15A, significant improvements were made to the electronics suite of the F-15C. The AN/APG-63 radar of the F-15C was equipped with a Programmable Signal Processor (PSP) which is a high-speed, special-purpose computer which controls the radar modes through software rather than through a hard-wired circuit. This allows much more rapid switching of the radar between different modes for maximum operational flexibility. The use of the PSP also paved the way for the modification of the APG-63 to make it capable of carrying out radar mapping in a synthetic aperture mode. Previously, such imagery had to be processed after the mission was over on the ground by large, high-speed computers because airborne equipment was too slow to produce images in real time. SAR imagery sharpens mapping details and provides an overhead view of the target to the pilot as if he were flying directly over the target, even though he may be as much as a hundred miles away.
The first F-15C (78-468) took of on its maiden flight on February 26, 1979. It was later used for trials with tangential carriage of bombs on the conformal tanks.
Some F-15Cs have provision for carrying up to 18 cluster bombs or six Mk 82 bombs, with the capability of releasing these weapons at supersonic speeds.
Most F-15Cs were delivered with Pratt & Whitney F100-PW-100 turbofans, but were later re-engined with more reliable but slightly lower rated (maximum afterburning thrust reduced from 23,830 to 23,450 pounds) F100-PW-220 engines. This engine was first tested on F-15A 71-0287. The -220 engine introduced single-crystal turbine airfoils, an advanced multi-zone augmentor, an increased airflow fan and a digital electronic engine control system. The new engine was introduced on the production line in November of 1985, and operational introduction took place in the spring of 1986. For the first time, F-15 pilots could confidently slam both throttles from Mil to Max AB and four seconds later get full thrust from each engine without having to worry about about the dangers of engine stagnations.
The improved F-15C/D began to be delivered to the USAF in the early 1980s. First to get the F-15C/D was the 32nd Tactical Fighter Squadron based at Soesterberg in the Netherlands, replacing the unit's earlier F-15A/Bs. These more potent Eagles then were issued to the 18th TFW at Kadena AB in Okinawa (marking the first Pacific deployment of the Eagle), and the 57th FIS at Keflavik in Iceland, and with a second squadron in the Alaskan Air command (the 54th TFS). With the exception of the 49th TFW, the F-15C/D replaced the F-15A/Bs in service with all of the USAF units that had previously been operating the Eagle. A total of 408 F-15Cs and 62 F-15Ds were delivered to the USAF. Many of the F-15A/Bs replaced by the more advanced Eagles were passed along to Air National Guard units.
78-0468/0495 McDonnell Douglas F-15C-21-MC Eagle 78-0496/0522 McDonnell Douglas F-15C-22-MC Eagle 78-0523/0550 McDonnell Douglas F-15C-23-MC Eagle 78-0551/0560 cancelled contract for McDonnell Douglas F-15C Eagle. 79-0015/0037 McDonnell Douglas F-15C-24-MC Eagle 0015,0017/0019,0023,0024,0028, 0031/0033 transferred to Saudi Arabia 79-0038/0058 McDonnell Douglas F-15C-25-MC Eagle 0038,0039,0043,0045,0051,0052,0055 transferred to Saudi Arabia 79-0059/0081 McDonnell Douglas F-15C-26-MC Eagle 0060,0062,0063 transferred to Saudi Arabia 80-0002/0023 McDonnell Douglas F-15C-27-MC Eagle 80-0024/0038 McDonnell Douglas F-15C-28-MC Eagle 80-0039/0053 McDonnell Douglas F-15C-29-MC Eagle 80-0062/0067 McDonnell Douglas F-15C-28-MC Eagle for Saudi Arabia, Peace Sun 80-0068/0074 McDonnell Douglas F-15C-29-MC Eagle for Saudi Arabia, Peace Sun 80-0075/0085 McDonnell Douglas F-15C-30-MC Eagle for Saudi Arabia, Peace Sun 80-0086/0099 McDonnell Douglas F-15C-31-MC Eagle for Saudi Arabia, Peace Sun 80-0100/0106 McDonnell Douglas F-15C-32-MC Eagle for Saudi Arabia, Peace Sun 80-0122/0124 McDonnell Douglas F-15C-27-MC Eagle for Israel, Peace Fox III 80-0125/0127 McDonnell Douglas F-15C-28-MC Eagle for Israel, Peace Fox III 80-0128/0130 McDonnell Douglas F-15C-29-MC Eagle for Israel, Peace Fox III 81-0002 McDonnell Douglas F-15C-32-MC Eagle - for RSAF 81-0020/0031 McDonnell Douglas F-15C-30-MC Eagle 81-0032/0040 McDonnell Douglas F-15C-31-MC Eagle 81-0041/0056 McDonnell Douglas F-15C-32-MC Eagle 81-0057/0060 cancelled contract for McDonnell Douglas F-15C 82-0008/0022 McDonnell Douglas F-15C-33-MC Eagle 82-0023/0038 McDonnell Douglas F-15C-34-MC Eagle 83-0010/0034 McDonnell Douglas F-15C-35-MC Eagle 83-0035/0043 McDonnell Douglas F-15C-36-MC Eagle 83-0044/0045 cancelled contract for McDonnell Douglas F-15C Eagle 83-0054/0055 McDonnell Douglas F-15C-35-MC Eagle for Israel, Peace Fox III 83-056/062 McDonnell Douglas F-15C-36-MC Eagle for Israel, Peace Fox III 84-001/015 McDonnell Douglas F-15C-37-MC Eagle 84-016/031 McDonnell Douglas F-15C-38-MC Eagle 84-032/041 McDonnell Douglas F-15C Eagle - cancelled contract 85-093/107 McDonnell Douglas F-15C-39-MC Eagle 0102 credited with 3 kills in Gulf War 85-108/128 McDonnell Douglas F-15C-40-MC Eagle 85-132/134 McDonnell Douglas F-15C-40-MC Eagle 86-143/162 McDonnell Douglas F-15C-41-MC Eagle 86-163/180 McDonnell Douglas F-15C-42-MC Eagle 90-263/268 McDonnell Douglas F-15C-49-MC Eagle For Saudi Arabia 90-269/271 McDonnell Douglas F-15C-50-MC Eagle For Saudi Arabia
Engines: Two Pratt & Whitney F100-PW-220 axial-flow turbofans, each rated at 12,420 pounds dry, 14,670 pounds at full military power, and 23,830 pounds with afterburning. Maximum speed: 1650 mph (Mach 2.5) at 36,000 feet, 915 mph at sea level. Cruising speed 570 mph. Initial climb rate 40,000 feet per minute. Service ceiling 65,000 feet. Maximum unrefuelled range 3450 miles. Dimensions: wingspan 42 feet 9 1/2 inches, length 63 feet 9 inches, height 18 feet 5 1/2 inches, wing area 608 square feet. Weights: 27,000 pounds empty, 40,000 pounds combat, 41,500 pounds gross, 66,000 pounds maximum takeoff. Fuel: Maximum internal fuel 1790 US gallons. Three 610-gallon drop tanks can be carried, one on the fuselage centerline and one on each of the underwing pylons, bringing total fuel capacity to 3620 US gallons. Armament: One 20-mm General Electric M61A1 Vulcan cannon in the starboard wing root with 940 rounds. Provision for four AIM-7F/M Sparrow or four AIM-120 AMRAAM missiles on hardpoints attached to the lower outer edges of the air intake trunks, two on each side. Four AIM-9 Sidewinders infrared-homing missiles are carried on the underwing pylons, two on each side.