Pressure

CCLXX

With the advent of the Boeing 314, Pan American Airways would spend the rest of its impressive existence dealing with and only with the Boeing Airplane Company. Boeing had originally been founded in 1910 under the name “Pacific Aero Products Company” by William Boeing. Boeing’s immigrant father had arrived in America toward the end of the 19^th Century. Working as a day laborer for a time, he soon amassed a small fortune by buying timberlands cheaply in remote areas.

William Boeing (1881-1956)

  

When William came of age he transferred his base of operations to the lumber-rich and easily-accessible coasts of the Pacific Northwest. Fascinated by flight, he decided to build airplanes (which were wooden at the time and made largely of spruce, a wood which Boeing cultivated in abundance). At first, business was slow, and Boeing’s other interests had to support the airplane factory, but after the sinking of the R.M.S. Lusitania in 1915, it became increasingly obvious that America would enter World War I. Boeing reincorporated Pacific Aero as the “Boeing Airplane Company.” In early 1917, Boeing released its first aircraft model, a civilian seaplane, the “B & W” or “Boeing Model One.” Less than a month later, the U.S. entered the war, and within days Boeing was building seaplanes for the U.S. Navy.  After World War I, Boeing established a wholly-owned subsidiary airline that the company called United Aircraft and Transport Corporation (UATC); Boeing’s partner in the venture was Pratt & Whitney. The airline was usually referred to simply as “United.” And it still is.

 

This Boeing logo represented the company from its founding until the 1950s

Boxy but efficient, the Boeing Model One was the first in a long and ongoing line of Boeing aircraft designs, many of which are memorable, once household, names

United Airlines and its classic “Stars and Bars” logo of the 1960s

Boeing concentrated on commercial craft for years, but the Model One military conversion was far from its last combat aircraft.  The Model 15 biplane of 1925 was Boeing’s first production foray into land-based fighter planes. A single machine-gun biplane capable of carrying two small bombs, the Model 15 was essentially unremarkable, but the basic design gave rise to the F2B and F4B, both carrier-based biplane fighters of 1928 and 1929 respectively.  They were used on the U.S.S. Langley, the United States’ first aircraft carrier.

The U.S.S. Langley  (CV-1) was born the U.S.S. Jupiter, a collier.  Note the biplanes. The success of the Langley led in the 1920s and 1930s to the development of the first-generation Lexington-class aircraft carriers, all of which saw service in World War II

Boeing was a company that was unafraid of improvisation. Thus, developments on the commercial side carried over into the military side, and vice-versa.

The Boeing Monomail (Model 200) owed a debt to the Hughes H-1 Racer with its low internally cantilevered wing and its flush-rivet skin. Although only two Monomails were built (Model 221 was designed to carry six passengers plus mail) the Monomail was the forefather of the B-247, B-307 and B-377 airliners and the XB-15, B-17, and B-29 heavy bombers

Like the Monomail Model 200, only one XB-15 bomber (Model 294) was ever built (in 1934). Although it had vast wings and an incredible payload capacity for its time, it was chronically underpowered. Ultimately, it was used to haul cargoes from the Lower 48 to the Panama Canal during World War II.  So much of the design however went into the B-17 and later the B-29 that this plane was affectionately called “Old Grandpappy.”

The XB-17 (Model 299) was rolled out in 1935 and was the first of the “Flying Fortresses.” It had more powerful engines than Old Grandpappy and differences in the landing gear, but it was very much like the XB-15 in all other respects. At the time, it was the largest landplane ever built in America

The first production run of the Model 299 was first designated the Y1-B17 (later just the B-17). It used Wright-Cyclone engines rather than Pratt & Whitneys, giving it more power. In 1936, the six B-17s represented the entirety of the U.S. heavy bomber fleet

The 1937-era Y1-B-17A (or just B-17A) had turbochargers added to its configuration, boosting its engine power

The B-17B replaced the “blister” windows with flat-paned sliding windows in the waist and the nose, but added little in the way of armor or armament. There was no tail gun, and most of the weaponry was .30 caliber. For a presumptively “offensive” heavy bomber the B-17 of 1938-1939 was a tiger without fangs

The B-17C was the first of the Flying Fortresses to go to war (1939-1941). Armor was added to vulnerable spots, some of the guns were upgraded to .50s, and the “blister” turret in the belly was replaced by a “bathtub” turret. Badly misused in combat by the British during the Battle of Britain, the “Fortress I” as they called it, proved to be ineffective and vulnerable, an embarrassment to Boeing and a danger to its crews. Herrmann Goering called them “Flying Coffins”

The B-17D was very similar to the B-17C, though an additional gunner joined the crew, as did “cheek” guns in the nose. The electrical system was upgraded, and even more armor was added. In December 1941, the B-17D went to war in the Philippines. The only existing B-17D, the oldest B-17, and the only one in existence with the “shark fin” empennage, is “The Swoose” of the Air and Space Museum. During the early critical months of the war, The Swoose was kept flying by cannibalizing parts from different planes, making it “half swan half goose.” The plane’s motto was, “It flys” (sic). The battle-scarred Swoose became the personal transport of General George Brett in 1942 and was flown to the U.S. as part of a War Bond drive, leading to its preservation

The B-17E of 1942-1943 was ten feet longer than previous Fortresses, carried larger and more guns including in the tail, a ball turret, and more armor, but was most distinctive for the large empennage which became the trademark of the wartime B-17s.

The enlarged empennage of the B-17E (and subsequent Fortresses) was an inheritance from the design of the Boeing 307 of 1939, which in turn had been built upon the design of the B-17C with the fuselage enlarged to 12 feet around, giving it the nickname “Flying Whale.”  The 307 was the world’s first pressurized production civilian aircraft, an innovation which it passed down to the B-29 bomber

The absurdly roomy interior of the Boeing Stratoliner puts modern-day aircraft to shame

 

The B-17F (1942-1944) had a single-piece Plexiglas nose, more fuel tanks, additional bomb load, cowl flaps, larger propellers, structural strengthening, and improved internal systems over the “E”. However, it still lacked adequate firepower in the nose, and was vulnerable to head-on attack by the Luftwaffe. About 3400s “Fs” were built, most by Boeing, but 1100 by Douglas and Lockheed-Vega under license

The B-17G  (1943-1945) was the most common, most lethal, and overall most powerful version of the B-17. Of the 12,731 B-17s built between 1935 and 1945, 8,860 were “Gs”. About half were Boeing planes. 25% were Lockheed-Vega models. and 25% were Douglas models. The licensed “Gs” were essentially identical, except for the nameplates. The “G” was given a chin turret to protect it from head-on attack. The tail turret was improved, as was the top turret. Overall, ten .50 caliber machine guns gave the “G” an impressive rate of firepower. Many “Fs” were retrofitted with the extra guns and new turrets, making them visually indistinguishable from “Gs”.   

The B-17 could take incredible combat punishment and keep flying. It more than deserved its name of “Flying Fortress”. This Fortress, Lovely Julie, took a direct hit from flak over Germany on October 15, 1944. The bombardier, George Abbott, was killed instantly, but the plane flew home despite the fact that the cockpit was open to the elements and the pilots could barely see anything through the windscreens. Not only did nine of the ten crewmen survive, but Lovely Julie  returned to combat status after being refurbished. 25% of all heavy bomber crews never made it home, the highest loss rate in the U.S. military during the Second World War. B-17s flew after the war in many air forces, finally retiring for good in 1959

Doc,   a recently restored B-29. Though built in 1944, Doc is a Korean War veteran, not a World War II veteran. After Korea, Doc served on the DEW (Defense Early Warning) Line in northern latitudes, until being mothballed at China Lake in 1956. Left exposed to the elements the plane was a mess when it was privately purchased for restoration in the 1980s. As one of only two extant  potentially flyable B-29s, Boeing assisted in the restoration project as a matter of pride, making Doc airworthy again. Doc slipped the surly bonds of Earth for the first time in 60 years in 2016.
The B-29 Superfortress was meant to be a pressurized version of the Flying Fortress and borrowed pressurization technology from the Boeing 307. The first, Model 345, flew in 1938. Its late wartime variants had remote-controlled guns, an automatic fire-control system, and the world’s most advanced avionics. The B-29’s service ceiling was 31,850 feet; unless damaged by errant flak or in low-level bombing, most aircraft of the day could barely engage with it. These planes firebombed Japan in 1944 and 1945, and two, Enola Gay and Bock’s Car, dropped atomic bombs on Hiroshima and Nagasaki respectively. The “atomic bombers” (“The Silverplate Series”) had enlarged bomb bays, lacked guns, and had reversible propellers and more powerful engines than earlier variants

The B-29 was remodified into a “D” variant (later called the B-50) in 1945 (it had larger engines and wings and a much larger empennage), but was superseded by the B-52 jet bomber in 1952. B-50s, nevertheless, served the USAF until 1965 

Though venerable, B-52 Stratofortresses have served in the USAF since their introduction in the early 1950s. Of 744 originally built (between 1952 and 1962) 78 are still in combat status, with constant upgrades to avionics and other systems. They have served in every major U.S. military engagement since 1955, and are most famous for their Vietnam War-era service

The Boeing 307 was midwifed by Howard Hughes who not only bought the first one to roll off the line but convinced William Boeing to build the plane in the first place. 

Hughes had early on realized that a pressurized aircraft had many advantages over an unpressurized craft, not the least of which was higher speeds at higher altitudes. A second advantage was the ability to fly above most weather systems. 

Cabin pressure is maintained at about 12 pounds per square inch (p.s.i.) on modern commercial aircraft (about one mile high, the elevation of Denver, Colorado). For comparison, sea level air pressure is about 14.7 p.s.i.

The aircraft’s turbofan engines feed off the oxygen in the air to operate, but some air is forced through the engines into a compressor. The compressor then pushes the air into and through the cabin to an outflow valve. So long as the engine is feeding air to the compressor, the compressor is feeding air through the cabin to the outflow valve, and the air is escaping outward, the cabin remains not only pressurized but supplied with fresh air.  

The twin tricks in flying a pressurized airplane are to maintain proper cabin pressure at all stages of the flight and to avoid depressurization. A slow leak can kill via anoxia. A catastrophic depressurization will cause the air in the cabin to expand outward and dissipate in the blink of an eye, explosively, taking everything and everyone aboard with it.

Although the Stratoliner was meant to be a commercial aircraft carrying a crew of six (including a Flight Engineer, a first for a landplane) and 33 passengers (along with overnight berths) at 220 m.p.h. at 20,000 feet, World War II derailed its service. TWA’s four Stratoliners were used for a few coast-to-coast commercial flights before they were seconded to the U.S. Navy for military service, mostly for transporting VIPs and sensitive cargoes. As military aircraft they were designated as the C-75. Hughes’ lavishly-appointed personal Stratoliner gathered dust.

Howard Hughes’ personal 307 rarely flew, but it was an archetype of early 20^th Century post-modernism. Today the fuselage is a houseboat

Pan Am’s Stratoliners went into formal commercial service in the Western Hemisphere, but the Clipper Flying Cloud, Clipper Comet, and Clipper Rainbow were mostly designated to fly war-related and diplomatic missions in the Latin American zone. Unlike the TWA planes however, Pan Am continued to own them.  

Boeing’s 307 Stratoliner Clipper Flying Cloud

They continued to fly until 1951, when they were retired by the arrival of the iconic triple-ruddered Lockheed Constellation. Both Pan Am and TWA sold their 307s to local operators. One became the Presidential plane of Haiti’s Papa Doc Duvalier; another was the flagship of the North Vietnamese national airline. It flew until 1986.

Although the Lockheed Constellation --- the “Connie” --- is associated in the public mind most with TWA, Pan American and the various airlines of the Pan American System also used these instantly-recognizable tri-tailed prop planes, which were really the first modern airliners. Daring in design and execution, the Connie seemed to epitomize post-World War II optimism and adventurism