The North American P-51 Mustang was a plane that very easily could have been relegated to the archives of “also-ran” aircraft. When we first looked at it almost 18 months ago, we noted that pilots praised its performance at medium altitude. Fast, nimble, forgiving, and very manueverable, the P-51 was a joy to fly…as long as the altitude didn’t soar. When it did, the Allison engine, a very capable powerplant, simply ran out of juice, leaving the plane sluggish and unresponsive.
So initial Mustangs were used predominantly in the close-air support (CAS) and reconnaissance roles, and they were very good. They finished the Second World War with the most bombs delivered per sortie of any fighter-bomber. But this role presented another weakness, again the result of the engine. The Allison engine was water-cooled, not air-cooled like radial engines (that powered, say, the P-47 Thunderbolt). So while they were hard to hit with ground-fire at low altitude, a lucky shot that damaged any part of the radiator or ducting could bring a Mustang down. This made them vulnerable as dive-bombers, coming in at a fixed angle of attack and maintaining speed until the bombs were dropped.
I suppose it was inevitable that, with the quality of the Mustang’s airframe, someone would suggest a change of powerplant. In April of 1942, the Chief Test Pilot for Rolls-Royce, Ronald Harker, took an Allison-powered Mustang up for a 30-minute flight. And after giving it some thought, he sat down with pen and paper on May 1, 1942 and wrote the words that would alter the Mustang’s history forever: “This aircraft could prove itself a formidable low- and medium-altitude fighter. It closely resembles the Me 109F, probably due to its being designed by one of the Messerschmitt designers, who is now working for North American Aviation Co. . . . The point which strikes me is that with a powerful and a good engine, like the Merlin 61, its performance could be outstanding, as it is 35mph faster than the Spitfire V at roughly the same power.”
And while Harker got the part about the Messerschmitt engineer wrong, the Rolls-Royce team (the builder of the Merlin engines) agreed with the rest of his assessment, and five aircraft were converted. What they saw in return was more than just a 4-bladed propeller that replaced one with 3 blades. They also got a staggering improvement in performance. Top speed jumped to nearly 440mph (H-models which saw very limited production were 40mph faster yet). Climb rates improved dramatically. The Mustang had been transformed from a medium-altitude fighter-bomber to a full-fledged escort fighter.
And the sounds!! If you’ve never heard a Merlin-powered Mustang, you’ve missed a treat. I was afforded the chance to see one in a local one-plane airshow many years back (a P-51B), and I still get goosebumps thinking about it…I’ll never forget it.
Anyways, enemy aircraft such as Germany’s Me 109 and Fw-190 were not only equalled, they were bettered. In the Pacific, the Japanese marks were swatted from the skies with an inevitability that shocks reason. They stood no chance against the Mustangs. Exploits like those of Major James Howard were made possible by the mixing of the Merlin engine (from the Spitfire) with the incredible airframe from North American engineer Raymond Rice and designer Edgar Schmued. At Nuremburg, Hermann Goering testified that when he saw fighters escorting bombers over Berlin, he knew the war was lost. The fighters he saw were Mustangs.
After the war, Mustangs continued in front-line USAF service until the 1950’s. By then, jet-powered planes were available, and the days of piston-engined fighters were finished. But the Mustangs lived on in the National Guard and were used by smaller air forces all over the world into the mid-1970’s.
Today, Mustangs are coveted by pilots and racers all over the world. Of the more than 16,500 produced, only several hundred remain, of which fewer than 200 are considered flyable. And those that do fly are maintained by their owners with fanatical care. Priced at roughly $40,000 in 1940, they now routinely fetch more than $1 million.
Saying anything is “the best” is fraught with peril. It tends to be subjective and opens a can of worms for an argument. And there were numerous high-quality planes when the war ended in 1945. Grumman’s high-powered, high-speed F8F Bearcat. The Hawker Tempest. Vought’s F4U-Corsair. The Fw-190D. Late-edition Spitfires. All could make a claim.
But I personally consider the Mustang to be the best piston-engined fighter of all time. It is stunningly beautiful, stunningly fast, and stunningly sonorous. Years ago, Luke Swann put together a video series called Great Planes, which was picked up by the Discovery Channel in the late 1980’s. I recorded the Mustang episode and watched it dozens of times…I really wish I still had it. I can’t remember his exact quote at the end, but in speaking of piston-engined planes, he says something very close to: “Compare the others to one another. The Mustang stands alone.”
I completely agree.
And if someone has gobs of money and has no place to spend it, please buy me a P-51D (H- or K-models would suit, too).
Recommended Reading: The Mustang Story