The North American P-51 Mustang was one of the greatest fighters of World War II.

Had life worked out differently, the Mustang could also have fought in Vietnam and flown against a Soviet invasion of Western Europe. In fact, it might even have replaced the A-10 Warthog.

The Piper PA-48 Enforcer was a modernized version of the P-51. It was the brainchild of David Lindsay, founder of manufacturer Cavalier Aircraft, who bought the rights to the Mustang in 1956.

The P-51 eventually became the Turbo Mustang III. But in 1968, in response to an Air Force search for a counterinsurgency (COIN) aircraft to fight in Southeast Asia, Lindsay moved the Turbo Mustang III and himself over to Piper Aircraft, maker of popular aircraft such as the Piper Cub. What emerged in 1971 was the PA-48 Enforcer, Piper’s bid for the COIN contract.

While fast combat jets are sexier, the idea of a propeller-driven aircraft for COIN work makes sense: their slower speed allows them to loiter over jungle to provide air support or spot guerrillas. Prop jobs are also cheaper and require less maintenance. A P-51 cost $51,000 in 1945, or about $675,000 today. The Enforcer would probably have cost around a million dollars. The A-10 Warthog cost almost $19 million apiece.

Nonetheless, a modernized Mustang was a curious choice. The P-51 had made its reputation in 1944–45 as an air-superiority fighter that was fast, maneuverable and, most importantly, long-ranged enough to escort B-17 and B-24 bombers deep into Nazi-occupied Europe. But with its lighter frame and liquid-cooled engine that would seize up if hit, it was not the ideal ground-attack aircraft; that honor was reserved for the heavier, clunkier but remarkably tough P-47 Thunderbolt. Unfortunately, the Air Force junked the Thunderbolt after World War II, which meant the more fragile Mustangs were used for ground attack in Korea, and took heavy losses in the process.

Re-engined with the Lycoming T55, which powered the CH-47 helicopter, as well as an ejection seat and other upgrades, the PA-48 may have looked like a Mustang, but most of its components were new. It had a maximum speed of 345 miles per hour, almost a hundred miles per hour slower than P-51. Then again, it would have been strafing Viet Cong, not dogfighting Messerschmitts over Berlin. While the P-51 had a bomb load of a thousand pounds, the PA-48 could carry a respectable six thousand pounds of bombs or rockets, which is more than some modern fighter jets carry.

Incredibly, through the 1970s, Lindsay and Piper pitched the Enforcer not just as a COIN aircraft, but also as America’s primary ground-attack plane. That role happened to be fulfilled by the A-10. It’s one thing to offer a prop job for a niche role like bush wars, but quite another to suggest it should replace a jet as a primary ground-attack aircraft.

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Not surprisingly, the Air Force said no thanks. But Lindsay, who had been a newspaper publisher, persistently lobbied Congress until the Air Force awarded Piper an $11.9 million contract in 1981 to build two prototype PA-48s for evaluation. War is Boring’s Joseph Trevithick obtained a copy of the Air Force test report through the Freedom of Information Act. While the testers found the Enforcer easy to operate and maintain, they also concluded it was underpowered, lacked maneuverability with a full bomb load and was too fragile.

On the other hand, compared to a heavily armored A-10, almost any aircraft would look fragile. But the air defense environment has become only more hostile since World War II. Not only are nations like Russia deploying more sophisticated surface-to-air missiles, like the S-400, but even irregular armies and terrorists groups like ISIS and Hezbollah are well equipped with antiaircraft missiles and guns. Combat missions for the F-35 will be challenging enough, even with stealth. The skies would be absolutely lethal for a 1945 aircraft.

True, the PA-48 would have been cheaper, but this virtue is rooted in a time when human life was cheaper. America lost almost forty-four thousand Army Air Force (the precursor to the U.S. Air Force) aircraft overseas during the Second World War, plus another fourteen thousand in training accidents in the United States. More than forty thousand airmen were killed in combat theaters, and that figure was even worse for the Germans and Japanese. The P-51 was considered high-tech for its time. But World War II aircraft and their pilots were essentially flying bullets, to be expended like so much ammunition in a massive war of attrition. Even Operation Rolling Thunder in Vietnam cost more than nine hundred aircraft.

Today’s pilots are expensively trained and politically expensive to lose. A pilot lost over Serbia or Syria has major diplomatic repercussions, which is why drones are becoming the aircraft of choice. The Air Force does like its high-priced jets, and cost is a lingering issue for hundred-million-dollar aircraft like the F-35. But while a propeller-driven aircraft might be useful to organizations like Special Operations Command that fight small wars in remote locations, America is not about to send upgraded Second World War aircraft against China or Russia.

In fact, the U.S. Air Force did eventually buy a propeller-driven counterinsurgency plane. Brazil's A-29 Tucano was selected in 2011 for the new Light Air Support contract. There are twenty aircraft on order.

But Americans won’t be flying them into combat. The planes are for the Afghan Air Force.

Michael Peck is a contributing writer for the National Interest. He can be found on Twitter and Facebook.

Image: Piper PA-48 Enforcer. Wikimedia Commons/USAF Museum