On the blog today, author Chris Bucholtz takes us through the development of the P5 B Mustang for his new Dogfight series title.
As an avid scale modeler, I am eagerly anticipating the arrival of a new kit of the P-51B Mustang – coincidentally, the subject of my new book in Osprey’s new Dogfight series. The Mustang is iconic, yet there has yet to be a state-of-the-art model in my preferred 1:72 scale – a surprising omission.
Another surprising omission from the story of the Mustang – and something I hadn’t really realized until working on this book – is what a work-in-progress the P-51B was even as it was entering combat. The pilots of the 354th Fighter Group (of the Ninth Air Force – not the Eighth, oddly enough!) were the only P-51B unit for about three months, and so they found themselves flying the most hotly-contested segments of any USAAF deep-penetration missions, beyond the range of the P-47 Thunderbolt and so right in the thick of the Luftwaffe’s concentrated fighter defenses.
But as the 354th took their mission to the Luftwaffe, the Mustang had a set of issues that could make it less dangerous to the Luftwaffe and more dangerous to its pilots.
The most frustrating chronic problem was ammunition jams. In high-G turns, the ammunition belts were prone to misfeeding and jamming the .50-caliber machine guns. In fact, what would have been the first USAAF victory in the P-51B was downgraded to a probable when a stricken Bf 110 escaped Glenn Eagleston after his four machine guns jammed. The issue was that the guns were mounted at an angle as part of North American Aviation’s efforts to create gun mounts that could accommodate machine guns or 20mm cannons, resulting in the guns being installed tilted to the side in the gun bays. The resulting kink in the ammunition feed became more acute under high G’s, causing the guns to stop shooting.
You can’t shoot what you can’t see, and visibility was also an issue in the P-51B. The “birdcage-style” canopy could hinder the view from the cockpit, but refitting Mustangs with the Malcolm hood (designed by North American but manufactured by Malcolm in the U.K.) could remedy that. But the windscreen also tended to fog up in dives, something that could only be fixed in later models of the Mustang.
Other issues presented life-or-death consequences to the Mustang’s pilots. Flutter in the tail section in a few aircraft resulted in the entire empennage tearing loose. A faulty uplock securing the landing gear doors could cause the wheel covers to drop in high-G turns, and the resulting shift in aerodynamic pressure across the wing could cause damage or even rip off a wing at high speeds. And a failure of metallurgy in the four bolts that held the engine to the airframe resulted in instances where the entire nose of aircraft separated from the airframe, with fatal outcomes for the pilots. This last problem was especially frustrating because North American had identified the issue with its bolts, and replacements were sourced in the U.K. – but the replacements themselves were found to be faulty!
The Mustang was vital to the success of the U.S. bombing strategy, so it kept flying even while solutions were being found to its problems. The ammunition feed problem was solved in the field by clever armorers, who used feed motors from B-26 turrets to pull the ammunition through the guns, overcoming the kinking problem. This solution was quickly written up, promulgated throughout the USAAF in the U.K., and resulted in the modifications being made to newly arrived Mustangs at aircraft depots and to Mustangs already in combat within the fighter groups.
The tail flutter solution came in the form of a vertical tail fillet manufactured by North American as a kit and added to P-51Bs and Cs in the field. This improved air flow across the vertical tail and reduced structural loads. The landing gear door uplock was improved as well, and replacement parts were quickly distributed across the Mustang fleet.
The engine bolt issue was also attacked locally, with extreme attention paid to metallurgy. Gradually, the entire fleet was retrofitted, and the experiences of Mustang operators in the field were relayed to North American, which built the changes into Mustangs coming off the assembly lines.
Breaking the Mustang of its built-in vices required fast thinking, outside-the-box problem solving and efficient communication on the part of ground crews in Europe and engineers at North American Aviation. Only when these unsung heroes overcame the P-51B’s problems did the Mustang become a war-winning fighter.
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