With the end of the Second World War the United States Army Air Force (USAAF) – which was to become the US Air Force (USAF) in 1947 – had vast numbers of its premier fighter on hand; the P-51 Mustang. This aircraft has achieved legendary status and served tremendously in both the air superiority and ground attack roles.
But even as the war was ending, so too was the domination of the Mustang. New jet designs were clearly the future and the P-51 (or F-51 as it was redesignated) was swiftly relegated to reserve status and then retired from US service by 1957.
However, due to the sheer number of the F-51s then appearing on the civilian market, plus its enduring reputation, the aircraft continued to be of interest. One company that looked to exploit this was Trans Florida Aviation Inc.
This company bought up surplus Mustangs and converted them into high-speed executive transports by rebuilding them into two-seaters, stripping the military equipment and fitting more comfortable interiors. They would also go on to make various improvements such as enhanced fuel storage, as well as configuring the aircraft for wing tip mounted tanks.
Called the Cavalier series, these were built in limited numbers and Trans Florida – which changed its name to the Cavalier Aircraft Company – started to look at military applications. In 1967 Cavalier was awarded a contract by the US Department of Defense to build several military-spec aircraft for export, fitted with uprated engines and built with an emphasis on ground attack.
This decision is a bit of a paradox as it both makes sense and is somewhat odd. It makes sense because the United States was deeply engaged in its war in Vietnam at the time and was also committed to supplying multiple allies around the world with equipment to fight communist insurgents.
This meant that the US was both providing large numbers of aircraft from its reserve inventories, planes like the Douglas A-1 Skyraider, and also developing new aircraft for the counterinsurgency role like the OV-10 Bronco and A-37 Dragonfly under the PAVE COIN program.
So, given its reputation, the idea of fielding improved F-51s seemed logical.
What makes the choice odd is that the Mustang, for all its reputation, wasn’t actually a great choice as a ground attack aircraft. It was somewhat fragile – hardly surprising considering it was built as an agile and long-range high-altitude fighter – and the cooling system on its Merlin engine made it susceptible to loss from ground fire.
It was probably this that meant the Cavalier Mustang’s weren’t bought in great numbers, with handfuls supplied to Bolivia, El Salvador and Indonesia. But this mild interest was enough to encourage Cavalier to develop a new variant. In 1968 they mated a Rolls Royce Dart turboprop to a Mustang to produce the Turbo Mustang III.
This had better payload and lower costs than the earlier Cavalier Mustangs, as well as ceramic armour protection for the pilot and engine, but didn’t interest the USAF.
It was here that the Piper Aircraft company got involved. One of the so-called “big-three” in light aircraft, Piper had produced thousands of planes for the US military. With PAVE COIN offering further sales possibilities, Piper wanted to get in on the action. And they thought the Turbo-Mustang was the perfect opportunity.
In 1971 Cavalier closed and transferred rights to the aircraft to Piper, who would develop the Mustang to its ultimate form.
The PA-48 Enforcer.
Two existing F-51s were heavily modified to create the new standard, most significantly with the fitting of a Lycoming T55 turboprop engine – the same basic type as powers the Chinook helicopter.
One of these demonstrators was lost during testing, but the second competed in a PAVE COIN evaluation, being flown by USAF pilots. Though it is reported to have done well, the USAF was not really interested any more. There were plenty of options on the market for supply to US allies and the USAF itself was already switching its ground support focus from the jungles of Vietnam to fighting the Soviet Union in Europe.
To this end they had issued a new specification– the A-X program. This required the USAFs next ground support aircraft to have good low altitude and long loiter abilities, high survivability, heavy payload and a powerful rotary 30mm cannon. Remarkably, Piper decided that the PA-48 was ideal for this job!
The company lobbied hard until in 1979 Congress finally agreed to allocate $12 million for Piper to build two demonstrators for testing.
These aircraft – the ultimate Mustang variant – bore only a familial resemblance to the F-51D with only ten percent of the parts in common between the two. Again, Lycoming T55-L-9 turboprops were the powerplant, producing 2,445 hp. Top speed was 403mph, but this wasn’t a great concern as the emphasis was on ground pounding rather than aerial performance.
To this end, armament was carried on ten wing pylons and the Enforcer was stated to be capable of carrying a range of weapons – including gun pods carrying the formidable GAU-13/A 30mm rotary cannons. Details are a bit confused on total weapons load, but of the figures out there 6,200 lbs sounds reasonable.
The two demonstrators were completed in 1983 and flew trials with the USAF in 1984. This was Piper’s last throw of the dice with the PA-48, and they made much to their political allies in Congress of the aircraft’s very low purchase and running costs.
But though the Enforcers were reportedly considered reasonable aircraft to fly by the USAF test pilots, they were vastly inferior to the new support aircraft that the Air Force was receiving – winner of the A-X competition.
The A-10 “Warthog”.
One suspects the USAF high command was also horrified at the thought of their pilots potentially going into action against the Soviet horde in what was, essentially, a Second World War aircraft.
The two PA-48s were relegated to museums, and that was that. Which is kind of ironic, considering what has happened since as it seems that the Enforcer was an aircraft that missed its window.
Just too late to really find a spot in Vietnam, it was too early for the Post-Cold War chaos. The War on Terror has seen a resurgence of interest in light, propeller driven aircraft, built with the same role in mind as the original PA-48s. In fact, in 2009 the USAF initiated the Light Attack/Armed Reconnaissance – or LAAR – program.
This specified the need for a new light counterinsurgency, ground attack and reconnaissance aircraft for supply to Afghanistan. PAVE COIN 2.0, if you like.
Sales of light attack aircraft in fact boomed through the late-2000s and early 2010s. Many of these are based on modified trainer aircraft that have a single turbine engine and moderate weapon carrying capabilities.
If it still existed today, the PA-48 would be something of a heavyweight in comparison to the current crop, but it is conceivable that with its heavier payload and solid pedigree, the Enforcer would prove a popular offering.