Airacobra. Bell s Controversial

Transcription

1 Bell s Controversial Airacobra The P-39 supported by the Central Texas Wing of the CAF was a welcome visitor to AirVenture It had been years since the type had been seen on the grounds. SCOTT SLOCUM 12 JUNE 2017

2 The ultra-rare P-39 as seen from the cockpit Budd Davisson 13

3 It s easy for lovers of air shows to think that World War II aerial combat was waged entirely by Mustangs and Corsairs with the help of the occasional Spitfire, P-38, and Wildcat. That s understandable because those aircraft constitute something like 95 percent of the flying warbird population. And as fighters go, they were the most produced. But not really. For instance, there were nearly three times as many Bf 109s produced as Mustangs, but when was the last original 109 seen at Oshkosh? (Never.) However, even U.S. production warbirds have their share of seldom-seen aircraft. For instance, there were more than 19,000 B-24s produced, yet only two still fly. On the fighter side, there were more than 9,500 Bell P-39 Airacobras built, but it has been years since we ve seen one at Oshkosh. EAA AirVenture Oshkosh 2016 changed that because the Central Texas Wing of the Commemorative Air Force had its Airacobra on the line, with Bill Fier from Austin, Texas, officiating from the flight deck and loving every minute of it. The P-39 is one of the most controversial U.S. fighters of WWII (if you don t count the Buffalo) for a lot of reasons. The fighter was the result of a 1938 request for proposal sent out by the U.S. Army Larry Bell s company was known for building unorthodox aircraft including the USAAF s first jet, the P-58 (front), the P-63 King Cobra (middle) and the better known P-39 Airacobra. Air Corps; Larry Bell and his design team, already known for finding unusual mechanic solutions for aerial problems, offered the U.S. Army Air Corps what was to be designated the P-39. As sleeklooking as any airplane from either side during WWII, its low-drag, ultra-sleek nose design was not done for aerial efficiency. It was the result of a dogged determination to pack a lot of firepower up where the engine usually went. There s a common presentation currently floating around the internet that starts out, Once there was this gun, and it points out how Republic designed the A-10 Warthog around the GAU-8/A Avenger Gatling gun. That s largely what drove the P-39 s nose design. One of the head designers was totally enamored with the T9 cannon built by the American Armament Corp., a division of Oldsmobile. The aircraft was to be a highaltitude fighter, and here was a 37-millimeter cannon (the same size as that on the Stuart tank) that could fire three 1.3-pound rounds a second down range that would pulverize any fighter the new design was likely to face. The cannon was to be paired in the nose with two of John Browning s exquisite.50-caliber machine guns. Every effort was made to aim the ordnance right down the nose, thereby increasing the pilot s targeting accuracy. So, ideally, the cannon would fire through the prop shaft. The fly in the ointment was that the cannon was too big to fit between the cylinder blanks of the Allison V-12 that was to power the airplane. So, rather than relocating the firepower, they relocated the engine! They put it behind the pilot with a 10-foot drive shaft going between the pilot s legs to a reduction gearbox with an offset output shaft that allowed the cannon to sit comfortably behind it and fire straight through it. Ingenious! It seemed like a good idea at the time. And it was sort of. The basic plan was that the Allison would be equipped with a GE turbosupercharger, but when the final design didn t meet the speed requirements and aeronautical cleanups were in order, the large air scoop for the turbo was eliminated, the turbo along with it. The airplane went into production with a single-stage, single-speed super (not turbo) charger. Turbochargers work well at higher altitudes, but engine-driven superchargers need a different drive ratio, a second speed, up high to further compress the thin air. With only a single-speed, single-stage blower feeding it, the Allison just couldn t 14 JUNE 2017

4 Had the Airacobra been produced with the two-stage supercharger it was designed with, its reputation as a fighter could have been greatly different. produce the power it needed as it went past 12,000 feet: The new airplane that had showed so much promise was severely hampered in the 20,000-foot-plus arena where SCOTT SLOCUM most aerial combat was initiated. The net result was that the P-39, not affectionately referred to as the Iron Dog, had a terrible reputation within the Royal Air Force (RAF) and USAAF. In fact, there was only one P-39 ace, Lt. Bill Fiedler, in the USAAF. On the other hand, the Russians liked the airplane. Nearly half of the Airacobras produced were ferried through Alaska to Russia (it was said that they navigated from crash site to crash site along the route), where the airplane (mostly later N and Q models) excelled in the low-altitude aerial combat situations that typified the Eastern Front. The top Eastern Front ace was Alexander Pokryshkin, who scored 47 victories in lend-lease P-39s, making him the highest-scoring Allied pilot in an American fighter. And, no, the Russkies didn t use the Airacobra primarily for tank-busting. That s mostly a myth. After the war, Cobras that were overseas were scrapped where they sat, and stateside P-39s were good for only one thing: being made into beer cans. Unlike the Mustang and Thunderbolt, the P-39 would find no home in Guard or Reserve 15

5 Looking at home in the Cobra s cockpit, Bill Fier must be aware of the gross differences compared to the B-52s and B-1s, he flew in the USAF. SCOTT SLOCUM PHOTOS units. For that reason, very few survived the postwar years, and most of the survivors did so only because bad luck sometimes turned out to be good luck. In July 1945, P-39Q-5-BE, AAF Serial Number , was being ferried to a Reconstruction Finance Corp. scrapyard when an engine problem resulted in an emergency landing at a remote duster s strip outside of Hobbs, New Mexico. The trip to the smelter had been derailed! Being of no value to the AAF, the airplane was simply abandoned, and it remained at the duster strip for years before being moved to be displayed in front of a high school in Lincoln, New Mexico. A local aircraft enthusiast bought the airplane and donated the beat-up airframe to the then-named Confederate Air Force in At the time, the airplane had recorded only 392 hours in its logs. The airplane was sold to a private restorer who got it in the air in Later, John Stokes, the founder and first leader of the Central Texas Wing of the CAF, bought it and again donated it to the CAF. It has been based at San Marcos since that time but rarely made its way to Oshkosh. Then Bill Fier of Austin, Texas, joined the CAF. I came out of the Air Force after 22 years that in- With no nosewheel steering, the pilot depends on brakes for steering. 16 JUNE 2017

6 cluded lots of time in B-52s and B-1s, he said. I went right to the airlines and retired after 14 years there. During that entire time, I had never flown a general aviation airplane. My first flight behind a propeller was in the right seat of a B-25 after I discovered the CAF. I was really struck by the history those airplanes represented and immediately set out to learn to fly them. It was almost as if I was learning to fly all over. It was huge fun and challenged me in ways I hadn t expected. I got my propeller checkout and my tailwheel endorsement at the same time and even bought a Stinson 108. So, there I was trundling along at 90 mph after so much time buzzing along in the B-1 and airliners. I loved it! To get into the P-39, I needed a minimum of 100 hours of T-6 time, and while I was doing that, I fell in with the Tora, Tora group that was flying the modified T-6s that had been part of the movie. I logged 300 to 350 hours in those doing air shows and got pretty comfortable in them. Then it was time for the P-39. Bill said preflighting it isn t much different than with any other airplane. Check the fuel 60 gallons on each side, which sounds high, but he said the airplane burns The lines are undeniably sleek, in a vaguely art deco sort of way. JONATHAN APFELBAUM about 60 gallons per hour, so it has pretty short legs. He also said, The POH says to pull the prop through three blades, but that must have been written by someone who had never tried to pull an Allison V-12 through. It s highly geared, so it is nearly impossible to do it with only one person. If it s cold, you prime it for seven seconds, make the mixture rich, and crank it with the mags on. It usually catches almost immediately. Once you have it running, you do your best to get to the runway and off the ground as soon as possible because it ll overheat quickly. We had a high-technology radiator made for it, which gives us much more flexibility on the ground, but we had a WWII pilot tell us that in North Africa they had to have it off the ground in 20 seconds or it would overheat. It doesn t have nose wheel steering, so you depend on the rudder and brakes. The brakes are multi-disc units and very effective, but they are also very rare. As in impossible to find. However, a gentleman came up to us at Air- Venture who had several complete brake units that are unique to the Cobra. That was like finding gold! The Allison V puts out 1,325 hp, and the airplane weighs only 6,800 pounds. That gives it a little more than 5-pounds-per-hp power loading, which is very respectable. Bill said he uses 50.5 inches of manifold pressure on 100 low-lead, and that gives him really 17

7 An interesting comparison of how much sleeker an airplane is with the Allison behind rather than in front. SCOTT SLOCUM solid acceleration. I start out with full right rudder and some rudder trim, he said, because the rudder isn t effective at the beginning and you try not to use up the brakes. At 60 mph, which happens quickly, the rudder kicks in and you rotate it at 100 mph. The gear is electric, and it takes around 35 seconds for it to retract. But once up, I hit my climb speed of 160 mph quickly. Then it goes uphill at 2,000 fpm. When he levels off at cruise, he sets up 1900 rpm (remember, the prop is geared) and 29 inches of manifold pressure. At that those numbers, it gives him 220 mph indicated airspeed cruise. Bill said, I can see why most pilots who flew the airplane like it so much. The controls are all quite light, and the roll rate is fairly high and immediate. There are no POH instructions for entry speeds for aerobatics, so all I ve done is roll it until I get more familiar with it. It stalls at 90 mph with the flaps down and 105 clean, and it s a surprisingly soft stall. The gear speed is 200 mph, and I fly the break at 200; so the gear can come out immediately. The electric flaps are also available at 200 mph and are infinitely variable with the switch being spring-loaded to off. So, you just put the switch down until you have what you want and let it spring back to off. They ll come down to 30 degrees, if you really want, but I seldom use them all because they generate so much drag when full down. If flying a power-on approach, I m using 110 mph, but power-off the POH says to keep it up around 130 mph with 100 over the fence in both cases. Some power is being used until right on the ground. As you flare, the nose is really high and it s like being in the back seat of a T-6. It s really blind! That s why the CAF requires so much Texan time. Once on the ground, I let it roll as long as it wants because replacing the brakes is something to be avoided. It rolls straight as an arrow, and even a strong crosswind is no big deal. If I have any regrets about flying the P-39, it is that I regret not having joined the CAF years earlier. This is such a huge opportunity to both experience and share history. Air show crowds are universally great and seem to appreciate what the CAF is doing with the airplane. Contrary to popular belief, the P-39 is much more than a footnote to history, and it s a shame that it is so overshadowed by the later designs. For that reason, the thousands of warbird addicts at AirVenture appreciated the effort that Bill and the Central Texas Wing put into having the airplane on display for the week. For the majority of the crowd, this was the first time they had ever seen the type in the air. It s not often we get to experience something that is usually only seen in aging black and white photos and movies. So, thanks, Bill. And thanks to the men and women of the Central Texas Wing. This made for a great AirVenture. 18 JUNE 2017