Just 29,000 pounds of ordnance screaming at twice the speed of sound.

On Valentine’s Day 1991, U.S. Air Force Captain Richard “TB” Bennett was at the stick of an search F-15 Strike Eagle, a ground attack variant of McDonnell Douglas’s search F-15 warplane. Throughout Operation Desert Storm, F-15Cs and F-15Ds would rack up 32 𝓀𝒾𝓁𝓁s against Iraqi planes, but Strike Eagles had a different mission—hunting and engaging mobile SCUD and surface-to-air missile platforms.

Bennett was on a SCUD patrol with his weapons systems officer Captain Dan “Chewie” Bakke when they received orders to engage a group of Iraqi gunship helicopters that were attacking American special operations troops on the ground.

“AWACS gave us a call and said that a Special Forces team was in trouble. They had been found by the Iraqis, who were moving to cut them off,” Bennett recounted in 2008. “We had ten to 15 Special Forces teams in the general area looking for Scuds. This team was about 300 miles across the border.”

Bennett instructed his wingman to fly about four miles behind him as he moved down through the early morning cloud cover. It wasn’t long before they spotted the five MI-24 Hind attack helicopters. The lead helicopter was on the ground for troops to disembark, clearly aiming to engage the Green Berets from air and land.

“We didn’t know exactly where our team was, but it was looking to us like things were getting pretty hairy for the Special Forces guys,” Bennett said.

Bennett and Bakke quickly decided to engage the lead chopper with a 2,000-pound GBU-10 laser-guided bomb. It was a bold decision, but the pilots were having trouble securing a radar lock for their AIM-9 sidewinder missiles, so Bennett decided that even if they missed the chopper, they’d still hit the ground.

But just as Bennett released the bomb, the chopper took off again. Almost instantly, the Hind’s airspeed read as 100 knots and climbing. Despite the helicopter being airborne and moving fast, the bomb still found its mark. The 2,000-pound shell smashed through the rotor, then the cabin, before detonating.

“There was a big flash, and I could see pieces flying in different directions. It blew the helicopter to hell, damn near vaporized it,” Bennett said.

“There was a big flash, and I could see pieces flying in different directions. It blew the helicopter to hell, damn near vaporized it.”

Captain Bennet’s story is only a small part of the search F-15’s gargantuan legacy as one of the Air Force’s most formidable fighter platforms. Built from hard lessons learned after the Vietnam War, the search F-15 has served with distinction—and with several variants—for nearly 50 years.

“During my time in Afghanistan, I flew combat missions in the aircraft that dropped the GBU-10 on the Iraqi helicopter in Desert Storm,” former U.S. Air Force F-15 and F-35 pilot Joseph Stenger tells  Popular Mechanics . “Knowing that I was part of that tradition was extremely special.”

But with the advent of fifth-generation fighters like the F-22 Raptor and the F-35, the F-15 seemed destined for the boneyard, collecting dust with other Cold War relics. But the twin-engine aerial powerhouse has proven too capable to retire.

In fact, the Air Force is buying all new F-15s for the first time in decades.

Lessons Learned From Vietnam

An F-4B Phantom attacks a Viet Cong position, 1966.Bettmann

Vietnam was a conundrum trapped inside of a quagmire—in more ways than one. For the Air Force, the situation was dire: American fighter pilots were dying at alarming rates.

In the Korean War, pilots in the cockpit of P-51 Mustangs and F-86 Sabres left the conflict with an impressive 13:1 𝓀𝒾𝓁𝓁 ratio. But in Vietnam, things were different. Fighters of that era had been designed with the ᴀssumption that the increased range allotted by air-to-air missiles had rendered dogfighting obsolete.

So jets like the F-4 Phantom were built without guns for close-range air combat and without the maneuverability found in Vietnam’s smaller, more nimble fighters like the Mig-21.

That once impressive 𝓀𝒾𝓁𝓁 ratio dropped to an abysmal 1.5:1.

With the death of dogfighting being greatly exaggerated, the Air Force needed a dedicated air superiority fighter to ensure their pilots would survive the next conflict. The request was lofty—the service wanted an extremely fast fighter with powerful radar, a large complement of air-to-air missiles, and a gun that could be used for close-range fighting with other jets. Most important of all, this new fighter had to be able to stand in the ring with the highly maneuverable fighters that wreaked havoc on American aviators in Vietnam.

“Coming out of the Vietnam War, it was evident that the United States couldn’t take air superiority for granted.”

By 1966, the Air Force had issued a formal request for a fighter that could dogfight with the best new fighters coming out of the Soviet Union. The Soviet roster now included the new MiG-25, which boasted a top speed of Mach 2.8. Concerns were mounting that the U.S. was being outmatched, so the Air Force once again adjusted their requirements for a new fighter, dubbed the FX (Fighter eXperimental) program, to include a power-to-weight ratio of 1:1, giving it exceptional speed and maneuverability.

“Coming out of the Vietnam War, it was evident that the United States couldn’t take air superiority for granted,” Stenger tells Popular Mechanics. “We needed a fighter that could not only engage Russian fighters in within-visual-range (WVR) combat, but also one that could utilize the latest technology to shoot down aircraft well before a dogfight ensued.”

James S. McDonnell founder discusses the search F-15 with Prince Charles while looking at a model of the fighter plane, 1977.Bettmann//Getty Images

McDonnell Douglas, North American Rockwell, and Fairchild-Republic all submitted proposals for the FX fighter program, but in a surprise twist, the Defense Department asked NASA to submit their own proposal as well. John Foster, Director of the Defense Department Research and Engineering organization, felt NASA would not only be able to offer a proposal that sat on the cutting edge of existing technology, but he also ᴀssumed NASA’s tenacity for problem solving would limit issues that might arise in further testing.

NASA’s findings, which included intense study of variable-sweep wing configurations, would go on to find a home in not only the eventual McDonnell Douglas search F-15, but also the Grumman F-14 Tomcat.

On December 23, 1969, McDonnell Douglas was awarded the contract to build the search F-15, incorporating design cues borrowed from NASA. The design utilized fixed wings and a wide fuselage that could serve as a lifting surface in itself. Almost immediately, production of 107 jets for testing and further development began. The first prototypes would take to the sky just three years later in 1972.

Those early F-15s looked remarkably like the ones still in service today with capabilities that would make many other fourth-generation fighters think twice about engaging in an aerial scrap. With two Pratt & Whitney F100-PW-100 afterburning turbofan engines capable of unleashing a whopping 23,500 pounds of thrust (with afterburners), the search F-15 was so powerful, it could break the speed of sound while flying straight up.

With the jet’s top speed maxed at Mach 2.5 (almost as fast as Russia’s legendary MiG-31 Foxhound) and an advanced AN/APG-63 nose mounted radar, the search F-15 could spot even low flying enemy planes at a range of up to 200 miles. Importantly, this radar system was also the first to use a programmable system processor that would allow for some updates and improvements without having to change out hardware. That approach has since become an integral facet of the F-35, which receives regular software updates to improve performance.

But the search F-15 Eagle didn’t just offer speed and firepower, it was also purpose-built for long haul missions because it could carry three 600-pound external fuel tanks that gave it a range of 3,000 miles—no aerial refueling needed. This incredible range coupled with the search F-15’s ability to cruise without afterburners at Mach 0.9 meant the F-15 could nearly traverse the world at a moment’s notice.

After less than a year of testing, the F-15 was put into serial production, first joining the roster for the U.S. Air Force, as well as allied nations like Israel and Japan.

A Dogfighting Dynamo

U.S. F-15, 1977.Bettmann

McDonnell Douglas’ efforts to field a competent air superiority fighter would begin paying dividends in just six years, scoring its first air-to-air 𝓀𝒾𝓁𝓁 in June of 1979, when an Israeli Air Force F-15A sH๏τ down a Syrian MiG-21.

Over the coming years, Israeli, Saudi, and American pilots would continue to add to the search F-15’s impressive win streak, logging 104 air-to-air victories without a single Eagle lost to enemy fighters. The list of fighters sH๏τ down by F-15s range from a spectrum of MiG iterations, Mirage F-1s, one transport plane, and of course, one Iraqi attack helicopter.

Uriel Sinai

Chip Hires//Getty Images

In order to achieve this incredible record, the search F-15 saw continuous upgrades, with the F-15C incorporating a newer and even more capable radar apparatus and new Pratt and Whitney engines. Some were even equipped with a radar-fed Joint Helmet Mounted Cuing System that allowed pilots to acquire targets even faster.

By 1986, the fighter had proven so capable that the decision was eventually made to field another new variant of the platform, the aforementioned F-15E Strike Eagle. While other F-15s were built to dominate air-to-air engagements, the F-15E leveraged the jet’s range, speed, and ordnance capabilities to become one of the most capable medium-range precision strike aircraft in America’s arsenal, with the B-1B Lancer absorbing the F-111 Aardvark’s supersonic bomber responsibilities.

“What separates the F-15E is the air-to-ground capability, especially in the close-air-support (CAS) mission set. The sensors, long on-station time, interoperability, and a vast array of available weaponry really set the F-15E apart from other fighters,” Stenger says.

The Strike Eagle was equipped with a LANTRIN (Low Alтιтude Navigation and Targeting Infrared for Night) forward-looking infrared laser and targeting pod. In all, the Strike Eagle can carry up to 24,000 pounds of ordnance into the fight. Combined with conformal fuel tanks added to give the F-15E even greater range, the search F-15 has enough firepower and fuel to make for an extremely effective close-air-support fighter plane.

“There are young aviators now who are better at strafing and CAS than I ever was,” search F-15 pilot Maj. Christopher M. Short said, “because they’re training at an early stage in their career. I walk into a squadron now, and it is second nature for these lieutenants to know that CAS [Close Air Support] is on the menu of things they might be asked to do. And they’re ready to do it.”

The Fighter of the Future Is an F-15?

An F-15E Strike Eagle takes off for a training sortie at RAF Lakenheath, U.K., Oct. 26, 2018.USAF/Matthew Plew

By 1991, the U.S. Air Force was already aware that they’d need a new air superiority fighter to maintain air dominance into the 21st century. Much like the dogfighting conundrum faced by the Air Force that first gave birth to the search F-15, the early 90s saw Air Force officials trying to predict the challenges of the years ahead in their requests for new fighter proposals, highlighting the need for a plane that could avoid detection as air defense systems continued to mature.

Lockheed Martin, who had revolutionized bomber strategy with its F-117 Nighthawk the decade prior, was selected to begin development of a new fighter that was unlike anything ever seen before in warfare.

It was to be fast and maneuverable like the search F-15, but capable of avoiding detection like the F-117. This new jet would come with thrust-vectoring jet nozzles to provide it with unparalleled maneuverability and even the ability to “super cruise,” or maintain supersonic speeds without the use of its afterburner. The technologically superior jet would also continue the dogfighting spirit of the search F-15. It was called the F-22 Raptor.

Initially, the Air Force intended to purchase 750 advanced fighters—enough to replace the F-15C and D, but budget concerns and a shift toward counter-insurgency and anti-terrorism operations in uncontested airspace left America unsure of its need for an air-combat specialty fighter. In 2008, the decision was made to halt production of the F-22 at 186 finished airframes, all but guaranteeing the search F-15’s continued use as America’s workhorse air superiority fighter for decades to come.

YF-22 Advanced Tactical Fighter conducting tests over Edwards Air Force Base, 1990.Time Life Pictures

It was good news for the search F-15, but bad news for maintainers. The Air Force had taken delivery of their final F-15 (a Strike Eagle) in 2004, four years prior to the F-22’s cancelation. That meant the U.S. Air Force would need to keep their existing F-15s in the air for far longer than initially anticipated. While the F-15 had proven resilient, the cost of maintaining these fighters, some of which were already decades old, continued to climb.

But now after nearly two decades, the U.S. Air Force is now once again purchasing new F-15s —but the decision to do so wasn’t without controversy. Many contend that in this era of stealthy fifth-generation fighters like the F-35 and F-22, there’s no need to throw more money into a fourth-generation platform like the search F-15. Those critics had their positions bolstered when Lockheed Martin announced in 2019 the per-aircraft price of the F-35 dropped to $78 million—$2 million less than Boeing’s new F-15EX

Aerospace propulsion technicians test an search F-15 Eagle engine at RAF Lakenheath, United Kingdom, Feb. 5, 2020.Madeline Herzog

But the comparison between the F-35 and the F-15 isn’t a fair one. The F-35’s multirole pedigree can be traced back to the F-16 Fighting Falcon, whereas the F-15’s intended replacement was supposed to be the F-22 Raptor. These fighters serve in very different roles, with the F-35 primarily intended to engage ground targets in contested airspace, and the search F-15(and its F-22 successor) built for air battles. As a result, new F-15EXs won’t fill F-35 slots, but rather will replace aging F-15Cs.

“It’s not the differences between the jets that really matter—it’s more the interoperability,” Stenger says. “The two aircraft that I flew, the F-15E and F-35A, provide complementary capabilities that make the U.S. Air Force extraordinarily effective at any mission and in any environment.”

And the F-15EX promises to be an incredibly capable and cost-efficient machine. Despite America’s decision to stop purchasing F-15s in 2004, America’s allies in Saudi Arabia and Qatar have continued purchasing the jet and invested a combined total of around $5 billion into continued improvements. The result is an search F-15 that’s more capable, more powerful, and more cost-effective to fly than its predecessors.

Concept art of Boeing’s new F-15EX.Boeing

Thanks to this mᴀssive investment, America’s new F-15EXs might be the most advanced fourth-generation fighters in the world, leveraging new data fusion capabilities, speed, range, and incredible payload capabilities to make an search F-15 that’s ready to fight in the 21st century.

With the ability to carry a payload of 12 air-to-air missiles or 15 air-to-ground weapons, (at least four times more than the F-35 can while maintaining stealth) and an integrated electronic warfare suite, the F-15EX isn’t as capable in highly contested airspace as an F-35 or F-22, but what it lacks in tact it makes up for in power.

In the future, the Air Force even intends to network stealth jets like the F-35 to missile-laden platforms like the F-15EX through a secure data-link. This link would allow the transmission of targeting data from forward stealth fighters to F-15EXs following behind, making it possible for the search F-15 to engage targets from greater distances. This would also give stealthy platforms a deeper magazine to pull from than their own internal weapons bays.

With new F-15s rolling off the ᴀssembly line and into the Air Force’s hangars, it seems clear that this powerful fighter born out of Vietnam’s treacherous dogfights will continue to savage the skies for a few more decades.

Because when stealth won’t do it, 29,000 pounds of ordnance under the wings of a jet screaming at twice the speed of sound is a good Plan B.

USAF/Bailee Darbasie