The F-15E Strike Eagle and its variants:
When the F-15 Eagle was designed in the late 1960s and early 1970s, some engineers were quoted as saying "Not a pound for air-to-ground" as a way of emphasizing the need to minimize weight. Less weight and more wing area equates to lower wing loading and greater agility. Nevertheless, the F-15 did have some potential for strike.
As usual, further details can be found in the Wikipedia article, but the origins of the strike variant go back to 1981 when the Air Force began planning for an F-111 replacement. McDonnell Douglas once again took home the gold, winning a contract to design and build the F-15E Strike Eagle.
The F-15E first flew in 1986 and the test program went smoothly, as the aircraft was so similar to the existing air superiority F-15C/D. The paint job on the F-15Es was different, but the primary external difference was the conformal fuel tanks (CFTs), which gave the E an extra 1,500 gallons of fuel. The aircraft was beefed up considerably to allow great ordnance and fuel; the takeoff weight increased to 81,000 pounds from the F-15C's 68,000. Empty weight increased, of course, and a loaded F-15E was no match in agility for the F-15C but that was not the mission. The CFTs when empty weigh over 2,000 pounds, but also can be fitted with bomb racks for extra carriage of weapons. The CFTs can also be detached to allow the E to be lighter, but they are almost always present.
In 1989, the 4th Fighter Wing at Seymour-Johnson AFB, North Carolina, became the first operational F-15E unit. Wings in Alaska, Idaho and the UK followed and the USAF took delivery of 236 Strike Eagles. They got their baptism of fire in the Gulf War of 1991 and have seen action on a number of occasions since.
Other countries watched the development of the F-15E with interest. Two operators of the air superiority models, Israel and Saudi Arabia were the first to order Strike Eagles and took delivery from 2006-on. Other orders followed: Korea (F-15K) from 2005 and Singapore (F-15SG) from 2009. Qatar ordered aircraft from 2016 and I believe has already taken delivery of part of the order; their F-15QAs are the cream of the crop, with all upgrades included.
The latest export customer is Indonesia, which has ordered 24 F-15IDNs (just one small squadron?) for future delivery.
A number of customers have specified an alternate engine for their Strike Eagles. The GE F110 is the same size and has similar ratings to the P&W F100.
Just a few years ago, concerned about the overall state of the tactical air capability of the USAF, the Air Force proposed putting the F-15 back into production, incorporating all the latest features as in the F-15QA, as the F-15EX. The F-15EX was conceived as a lower-cost alternative to more modern stealthy fighters and was proposed as a replacement for older F-15s in existing squadrons. Some sources state that the F-15EX will be stationed only in the U.S., but recently I have learned that consideration is being given to providing F-15EXs to the former F-15C squadrons in Okinawa, Japan. It's not clear how that will play out. Projections are that several Air National Guard F-15C squadrons will get EXs, which have two seats but can be flown solo by one pilot. Again, the future is not clear. It is also unclear how many F-15EXs will be built; the original program was for 144 airplanes and 70 have been funded so far. Just four have been delivered to the Air Force to date.
The concept for the F-15EX is that it can be a dual-role aircraft: Without CFTs and flown solo it can be equivalent to the F-15C and with CFTs can be loaded up with bombs and function as an F-15E. The F-15EX is the first USAF F-15 to have GE F110 engines.
The production total for the Strike Eagle is likely to be well over 600 by the time the last one is delivered some years from now; an impressive total for an aircraft that first flew in 1972 when added to the 1,198 air superiority F-15s.
https://en.wikipedia.org/wiki/McDonn...E_Strike_Eagle
https://en.wikipedia.org/wiki/Boeing_F-15EX_Eagle_II