As the United States marks the 40th anniversary of the first flight of the F-15 Eagle on July 27, the aircraft many still consider to be the world’s best fighter is on duty, standing guard, ready for battle.

Watching an Eagle make an afterburner takeoff can be exciting. Two 23,450-pound thrust Pratt &Whitney F100-PW-220E turbofan engines now power all of the 249 F-15C/D models in service, although most rolled out of the factory doors with earlier F100-PW-100 powerplants.

The F-15 is big. The pilot sits high atop this twin-engine fighter on a tall, almost stalky undercarriage. With its straightforward but very large wing of 608 square feet (wing span being 42 feet 9-3/4 inches), the Eagle is one of the few fast jets which has no need for a braking parachute: it has a “barn door” dorsal speed brake that enables it to land smoothly and gently.

The Eagle was designed to yank and bank with MiGs and to defeat the latest Soviet fighters. Today, more likely than any dogfight is the terrifying prospect that an Eagle pilot may be called upon to shoot down a hijacked airliner — taking innocent lives in order to save a larger number of innocents. It’s called the Aerospace Control Alert (ACA) mission. F-15 pilot Lt. Col. Rick “Ammo” Morris of the 123rd Fighter Squadron, Oregon Air National Guard in Portland, described it:

“We have 24-hour, 365-day alert coverage,” said Morris in a May 21 telephone interview. “Pilots stay on 24-hour shift in an alert facility with sleeping, eating and living quarters. They’re on edge ready to scramble on a moment’s notice any time the horn goes off. Our goal is to be airborne in five minutes, even if you’re in a dead sleep. Once the horn blows you don’t know where you’re going, how fast you’re going. As soon as the first engine gets started you get on the radio: ‘Where is the target of interest?’ ‘Where are we going?’ A lot of times, you can get airborne without knowing where you’re going.”

The F-15 has sleek lines but even at a glance there’s no mistaking the fact that it’s a warplane.

Burrows remembered, “This aircraft performed well from the first minute. We knew we had a winner from the start.”

The F-15 is big. The pilot sits high atop this twin-engine fighter on a tall, almost stalky undercarriage. With its straightforward but very large wing of 608 square feet (wing span being 42 feet 9-3/4 inches), the Eagle is one of the few fast jets which has no need for a braking parachute: it has a “barn door” dorsal speed brake that enables it to land smoothly and gently. The business end of the Eagle is straightforward — a 20 mm M61A1 Vulcan “Gatling” six-barrel cannon mounted in the starboard wing root with 940 caseless rounds. A typical air superiority load would include four AIM-9X Sidewinder heat-seeker and four AIM-120 AMRAAM radar-guided missiles. The F-15E Strike Eagle, unique in having air-to-ground capability, can carry almost every air-to-ground weapon in inventory, including satellite-guided munitions.

The design of the Eagle dates to 1965, when the U.S. Air Force was looking for a dedicated air superiority fighter under the FX program. This led to the premier flight of the first F-15A (71-0280) by test pilot Irving L. Burrows on July 27, 1972.

When he landed from that uneventful maiden voyage, Burrows proclaimed: “It was just like the simulator!” In a 2008 interview, Burrows remembered, “This aircraft performed well from the first minute. We knew we had a winner from the start.”

The series began with the F-15A and the combat-capable two-seat model, originally the TF-15A and now designated F-15B. The first two-seater (71-0290) flew on July 7, 1973.

In June 1979, these versions were succeeded in production by the F-15C and its two-seat version, the F-15D. These have 2,000 pounds of additional internal fuel and can carry CFT (conformal fuel tanks) containing 9,750 pounds of additional fuel. The Hughes APG-63 radar so well known to Iraqi pilots has been constantly improved. A decade later, it became a lightweight X-band pulse-Doppler radar with a reprogrammable signal processor. Today, the Air Force is seeking to upgrade as many of its currently serving F-15C/D Eagles as possible with Raytheon AN/APG-63(V)3 Active Electronically Scanned Array (AESA) radar, a process that is moving slowly because funding has been slow.

First blood for the F-15C model was drawn during a period of border tensions when two Saudi Arabian F-15Cs shot down two Iranian F-4E Phantoms over the Persian Gulf on June 5, 1984, possibly the only time one McDonnell fighter scored an aerial victory over another.

F-15Cs scored 32 aerial kills of a total of 41 victories in Operation Desert Storm in 1991. Of these, all but eight were achieved with the Eagle’s beyond-visual-range weapon, the Sparrow missile.

The F-15E has been a kind of second-generation Eagle, introducing a “mud-moving” role for the first time. Following test work with the no. 2 two-seater (71-0291), the first production F-15E (86-0183) flew on Dec. 11, 1986. Some observers liken the F-15E to the British Tornado for its bad weather, precision strike capability, though the latter aircraft is far less inclined to go MiG-hunting after the bombs are dropped. The U.S. Air Force has 224 Strike Eagles in inventory today.

When the United States launched Operation Desert Shield on August 6, 1990, days after the Iraqi invasion of Kuwait, the 1st Tactical Fighter Wing at Langley Air Force Base, Va., under Col. John M. “Boomer” McBroom – earmarked for Middle East duty under U.S. Central Command, or CENTCOM – began deploying F-15C/D Eagles on just hours’ notice. Forty-eight Eagles made the longest fighter deployment in history, flying 14- to 17 hours nonstop from Langley to Dhahran, with six to eight air refuelings en route.

F-15Cs scored 32 aerial kills of a total of 41 victories in Operation Desert Storm in 1991. Of these, all but eight were achieved with the Eagle’s beyond-visual-range weapon, the Sparrow missile. Seven kills were racked-up by AIM-9 Sidewinders and one by out-maneuvering an opponent, which flew into the ground. The AIM-120A AMRAAM was not fired in anger, although more than a thousand “captive carries” of the missile were racked up during combat missions in the final days of the war.

The inside of the Eagle and the nomenclature for its weapons have both evolved over the years, and McDonnell Douglas merged with Boeing in 1997, but the basic shape of the aircraft is unchanged since 1972. Burrows was exactly right. The F-15 Eagle was a winner from the start.