31 July 2015

The USAAF Looks for Something Better than a C-47

Loading a Jeep into this RAAF C-47 shows it wasn't ideal for large or bulky loads.
During the interwar period of the 1920s, US military air transport was modest at best and consisted primarily of "off the shelf" civilian designs that were modestly modified with things like reinforced cabin floors and wider doors but were essentially airliners without seats. Until 1934, for example, the US Navy and Marine Corps relied on Ford Trimotors for transport! The arrival of the Douglas DC-2 offered a big improvement in capability for the US military. With war clouds looming in Europe and Asia in the 1930s, the US Army Air Corps went about looking for something better than adapted DC-2s. Bids were requested and Douglas offered an attractive proposal for upgraded DC-2 aircraft better tailored to military transport operations. Not long after, General Henry "Hap" Arnold became head of the USAAC (which later became the USAAF) and being a personal friend of Donald Douglas, was well aware of a DC-2 upgrade in the works that was the result of a marathon telephone conversation between Donald Douglas and the head of American Airlines, C.R. Smith. That aircraft was a leap in performance and capability over the DC-2 and at the time was called the Douglas Sleeper Transport (DST). In due time, of course, the DST became the DC-3 but General Arnold saw the DST's design and performance as an ideal basis for a transport. Army officials met with the designer of the DST, Arthur Raymond, and the C-47 was born. When the war finally broke out with the German invasion of Poland in September 1939, the C-47 wasn't yet in production and suddenly the branches of the US military needed air transport aircraft. The C-47 Skytrain (Dakota in RAF service) made its first flight on 23 December 1941 as Douglas embarked on a major facility expansion to meet the demand for the C-47. At production peak in May 1944, the company was building just under 19 C-47 aircraft each day! Despite the massive expansion and number of C-47s needed, the Army did have several issues with the C-47 but it was the best aircraft available at the time. There were three main issues the Army had- the first was that the tailwheel configuration and side cargo door made it difficult to load large items. Secondly, the maximum payload was too light as it was based on the maximum civilian load for the DC-3, and thirdly, the Army felt that as it was a DC-1/DC-2 derivative, it was old technology. With the United States now in the war, the Army thought that aluminum production was best used for armed combat aircraft and that cargo aircraft which operated in support roles ought to use non-strategic materials. While there was never a formal competition for a C-47 replacement but rather a series of issued requirements, quite a bit of money was spent over the course of the war to develop a transport that was better than the C-47. 

Budd C-93/RB-1 Conestoga
At the outbreak of war, several aircraft made out of the non-strategic materials made the first attempt at replacing the C-47. The first came from the E.G. Budd Company of Philadelphia- they had developed the shotweld technique for joining two pieces of metal- it used a short burst of electrical current to bond two pieces of metal. Invented in 1932 by a Budd engineer, shotwelding was used on the products Budd was known for- railroad cars and road vehicle bodies made of stainless steel. In discussions with the US Navy, Budd hired an aeronautical engineering staff to design a shotwelded (therefore no rivets) transport that would be made of readily available stainless steel. The Navy ordered 300 to be designated the RB-1 and the Army ordered 600 to be designated the C-93. Though made primarily of thin-gauge stainless steel, the wing aft of the spar and the moving surfaces of the tail were fabric covered to offset the weight of the steel. 

The design of the Conestoga was radical for the day and set the pattern for an efficient military transport even to this day. A high mounted wing allowed for an unobstructed main deck with a tricycle landing gear to keep the main deck level and low to the ground to ease loading. An aft loading ramp/door allowed rolling stock to be driven on/off of the aircraft. The flight deck sat up above the main cargo deck to maximize the cargo volume of the fuselage. In addition, there was an integrated hoist in the cargo deck to ease loading an locations that lacked ground equipment. The first flight was on 31 October 1943 and three prototypes conducted the flight test program. Using the same engines as the C-47, the Conestoga was underpowered and possessed sluggish handling- pilots joked that for a plane made by a railroad car company, it sure handled like one! By time time cost overruns and construction delays were resolved at the Budd factory, aluminum production had vastly increased in the United States and the need for an aircraft made of non-strategic materials diminished. The Army canceled its order for the C-93 and the Navy reduced its order from 300 to just 25. Just 17 RB-1s were delivered to the Navy by March 1944 and that small number served primarily as hacks for naval air stations. With such a small number in the fleet, the Navy found the RB-1s uneconomical and sold them off as surplus in early 1945 before the war even ended. Twelve Conestogas were purchased by a new cargo operation, National Skyways, that was founded by a group of pilots that had once served with the American Volunteer Group in China. National Skyways would later change their name to Flying Tigers- but that's a story for future blog article!

Curtiss C-76 Caravan
Another aircraft from the Army's concerns in 1941 that was a contemporary of the Budd C-93/RB-1 Conestoga was the Curtiss C-76 Caravan. The company was engaged by the Army that year to build a transport aircraft that like the Conestoga, would not only be made out of non-strategic materials but also exceed the performance and utility of the C-47. The Caravan was designed by the chief designer at Curtiss, George Page, who was also responsible for the C-46 Commando. While the Conestoga would be made of stainless steel, Page elected to use wood for the Caravan but interestingly, the only high performance aircraft at the time in production made from wood, the De Havilland Mosquito, wasn't used as a source of expertise. De Havilland used a layered plywood construction using a lightweight balsa wood core that made the Mosquito strong but light. Curtiss engineers instead favored mahogany in layers- being a much denser wood than what was used on the Mosquito, the Caravan soared in weight. Despite this, the Army helped Curtiss secure large stocks of mahogany and a number of furniture manufacturers were set up as component subcontractors with final assembly at Curtiss's new plant in Louisville, Kentucky. 

Much like the layout of the Conestoga, the C-76 Caravan featured a retractable tricycle landing gear to keep the main deck level. It also had a high wing layout for an unobstructed main deck hold and also put the flight deck above the main deck. Instead of an aft loading door and ramp, the Caravan had a swing nose that opened to the side ahead of the flight deck. The prototypes were built at existing Curtiss facilities in St. Louis as well as the new Louisville plant with the first flight on 3 May 1943. The flight test program was a disaster. The aircraft, using the same engines as the C-47 but made of dense mahogany, was woefully underpowered with a cargo payload not much more than the C-47. On the first flight, the aircraft vibrated so badly the flight test crew made a hasty return to the St. Louis Lambert Field. On the second test flight, the prototype literally shook itself apart with the loss of the pilots. In addition, when empty, the Caravan had to be ballasted to maintain its center of gravity- amusingly, the ballast needed to maintain an empty load CoG was more than the maximum payload! The control surfaces suffered from buffet and even shook while the plane was on the ground if it was windy. The wing spar failed load testing eight times, only holding up to 40% of the predicted maximum load. The Army wasn't pleased and was more than happy to cancel their order for 175 C-76s, particularly as aluminum production had vastly increased as the war progressed. Only 14 aircraft were built and most spent their days as ground instructional airframes. 

Wind tunnel model of the Waco C-62
There was a third aircraft that stemmed from the Army's 1941 call for something better than the C-47, but it never flew. Waco Aircraft had been building both training and assault gliders for the military and they tendered a design that received the designation C-62. Like the Curtiss C-76 Caravan, the Waco design was made out of wood and featured a high wing and rear loading door/ramp. The tadpole-shaped aircraft had the empennage cantilevered over the aft ramp on a boom. The undercarriage was fixed as well. Using the same engines as the C-47, the Army placed orders for 13 pre-production examples and 240 production aircraft. However, again, like the Conestoga and Caravan, the anticipated shortage of aluminum never occurred and the C-62 was canceled. Allegedly the first aircraft was nearing completion at the time of the cancellation, but this hasn't been confirmed. 

Fairchild C-82 Packet at the National Museum of the USAF
The last aircraft that sprang from the 1941 call was the Fairchild C-82 Packet. Designed by Fairchild's chief designer, Armand J. Thieboldt, the original plans were for the C-82 to be made of wood. Like the other three aircraft, the Packet had a high wing and tricycle landing gear to allow for a level main cargo deck that was unobstructed. The flight deck was raised above the cargo deck and a twin boom layout was chosen to leave the tail area completely clear for straight though loading and unloading. With the fortunes of war shifting in favor of the Allies in the summer of 1942 after the Battle of Midway and an expansion of domestic aluminum production eased shortage concerns, the USAAF requested that Fairchild abandon wood for the C-82 and go with aluminum. Of four aircraft designs for a C-47 replacement, the decision to switch to aluminum more than likely contributed to the reasons why the Packet did get to production and service. Being the last submission probably saved the design as it was also redesigned to take a more powerful engine, the Pratt & Whitney R-2800 Double Wasp instead of using the same engines as the C-47. As a result, the C-82 had the highest cargo payload of the four designs. 

First flight took place on 10 September 1944 at Fairchild's plant in Hagerstown, Maryland. The first series of flights were so encouraging that the USAAF ordered 100 C-82s just 18 days after the first flight. With an eye towards the coming invasion of Japan, North American's Dallas plant was planned for an additional 1000 C-82s on top of an additional 100 from Fairchild for a total of 200 from the Hagerstown plant. The first C-82s were delivered to the USAAF in June 1945 but the sudden end of the war with the Japanese surrender in September 1945 resulted in the cancelation of the North American production run at Dallas with only just three Dallas-built C-82s being built. Despite the drawdown in US military forces, the C-82 Packet was the C-47 replacement the USAAF wanted and the 200-aircraft order from the Fairchild plant in Maryland stood to fulfill postwar airlift requirements. Five C-82s participated in the Berlin Airlift, bringing in heavy equipment and vehicles that couldn't be accommodated onto the Douglas C-54 Skymasters. Operational use of the C-82 revealed several shortcomings, the most concerning of which was that with a full load, a C-82 with one engine out couldn't maintain level flight. Thieboldt and his team at Fairchild went about improving the C-82 design first by incorporating more powerful engines in the form of the Pratt & Whitney R-4360 Wasp Major as well as a host of other improvements to satisfy the newly-independent US Air Force's concerns. Originally designated XC-82B, the changes were so significant that a new designation was assigned to the upgrade which became the C-119 Flying Boxcar. The first flight was made on 17 December 1947. As C-119s were delivered to USAF units, the C-82s were retired. A total of 220 Packets were built. Quite a few Packets had long civilian careers, but that's a story for future blog article! 

Source: The Legacy of the DC-3 by Henry M. Holden. Wind Canyon Publishing, 1996, pp 141-148. Information also from National Museum of the USAF, Wikipedia and www.c82packet.com. Photos: Wikipedia, Australian War Memorial, National Museum of the USAF. C-62 wind tunnel model from R/C Groups forum.

26 July 2015

Jaki Jakimiuk and the PZL Fighters: The Roots of the De Havilland Beaver

Jaki Jakimiuk
In telling the story of the development of the De Havilland Canada Beaver, there were many brilliant minds at De Havilland Canada and no story of the development of any aircraft can be fully told without looking at previous design influences. Often in aviation history, military aircraft have design influences on civilian aircraft- sometimes the design lineage is obvious, like the pathway from the Boeing B-29 Superfortress to the Boeing 377 Stratocruiser. Sometimes the path of development is parallel but intertwined, like that of the Lockheed C-5 Galaxy and the Boeing 747. And sometimes individual designers bring their experience to a project that leaves their stamp on it- like Jack Northrop's influence on Douglas designs from his time working for Donald Douglas. In the case of the De Havilland Canada Beaver, the experience of the company's chief design engineer, a gregarious Polish emigre named Wsiewolod "Jaki" Jakimiuk and his prior work before the Second World War with the PZL series of fighters, would, combined with the talents of his colleagues that the De Havilland's Downsview facility, create one of the greatest bush aircraft of the skies. 

Zygmunt Pulawski
The story begins with the Polish aeronautical engineer Zygmunt Pulawski. Born in 1901, Pulawski made a name for himself as a student at the Warsaw University of Technology designing and building his own gliders. Graduating in 1925, he went to work in France for Breguet, gaining valuable experience in aircraft design and construction. After two years he returned to Poland, became a pilot and by 1927 was the chief designer at the Central Aviation Workshops in Warsaw which was soon reorganized into PZL (the Polish abbreviation for State Aviation Works). It was in that capacity he submitted the winning design for a 1928 requirement from the Polish military for a new fighter aircraft, the PZL P.1. At PZL, Pulawski pushed his team to all-metal construction at a time when many fighter aircraft were still biplanes with fabric and wood components. At the time of its first flight in 1929, the P.1 was one of the most advanced fighter designs in the world with its gull winged monoplane wing, slim nose with a Hispano-Suiza V-12 engine and a finely corrugated metal skin that would be imitated by many contemporary designs. Pulawski's gull wing was so that the wing roots met the fuselage at the most aerodynamically optimum 90-degree angle and the cylinder heads of the V-12 engine matched the angle of the wing roots, giving the pilot excellent forward visibility compared to contemporary fighter designs. 

Model box art showing the P.1 configuration
The P.1 was showcased throughout Europe and even was demonstrated at the 1932 Cleveland Air Races in the United States. At a 1930 fighter competition in Bucharest, Romania, the P.1 made an excellent showing against contemporary types which included the Bristol Bulldog and the Dewoitine. The P.1, however, remained only a prototype as the Polish military preferred the Bristol Mercury radial engine which was being license built in Poland at the time. Pulawski, however, developed the P.1 design further with more powerful V-12 powered aircraft, the P.8, which first flew in August 1931. However, the two P.8 prototypes had cooling issues in the engine, but more importantly as a setback, Pulawski had perished in a crash on 31 March 1931. Lacking a strong proponent for streamlined in-line engine designs, the P.8 was canceled by the Polish government. 

The radial engine-powered P.6
At the time that the Polish military pushed for the incorporation of the Bristol Mercury radial engine into the P.1 design, Pulawski's assistant engineer was Jaki Jakimiuk. Prior to Pulawski's death, it was decided to forgo the Bristol Mercury engine and go with the more powerful nine-cylinder Bristol Jupiter engine with 500 horsepower which was also built under licence in Poland as well. The P.6 first flew in August 1930 and had a new, more streamlined fuselage and empennage and a Townend ring to improve the airflow over the protruding radial heads in the nose. Interestingly, the design of the DHC Beaver would go through the same transition, originally envisioned with an inline engine in a slim nose but ended up with a more robust radial engine. Like the P.1, the P.6 elicited quite a bit of interest in aeronautical circles worldwide- it was demonstrated at the 1931 Paris Air Show and it also won the 1931 National Air Races in the United States which were hosted by Cleveland, Ohio, that year. The P.6 also remained a prototype as a more refined design, the P.7, succeeded it. 
PZL P.7 in Polish Air Force markings

The P.7 was a P.6 with a more powerful variant of the Bristol Jupiter radial that had now had 520 horsepower, but more importantly, featured a supercharger for improved performance at altitudes over 10,000 feet. In addition, some of the aerodynamic refinements to the wings that were used on the P.8 were incorporated into the P.7. The Townend ring used on the P.6 was increased in chord for improved aerodynamics. One interesting feature of the design is that the main fuselage fuel tank which was located behind the engine but ahead of the cockpit, could jettisoned in case of an engine fire. The P.7 went into production and became operational in 1933 at which time the Polish Air Force became the first air force in the world to be completely equipped with all-metal monocoque fighter aircraft. By this time Jaki Jakimiuk had succeeded Pulawski upon his death and the PZL works in Warsaw were hosting technical delegations from aircraft companies throughout Europe. Jakimiuk himself often hosted the delegations who came to study PZL's techniques and discuss Jakimiuk's design philosophy. In 1937, a delegation from De Havilland came from the UK to meet with Jakimiuk for an exchange of ideas. At the time, De Havilland was working on its first all-metal airliner, the DH.95 Flamingo. One of the engineers doing an internship on the Flamingo project was Dick Hiscocks, a graduate of the University of Toronto who would eventually join Jakimiuk's team at De Havilland Canada as its aerodynamicist.

The PZL P.11, Poland's primary fighter at the outbreak of the war
At the outbreak of the Second World War with the invasion of Poland in September 1939, three Polish Air Force squadrons still flew the P.7- though more maneuverable than any Luftwaffe fighter and able to operated from grass fields with a takeoff run under 500 feet, the P.7s were simply outclassed by the Luftwaffe's Messerschmitt Bf 109s. But in 1931, the war was far in the future and Jakimiuk and his PZL team refined the P.7 further to create the P.11 which first flew in August 1931. Even before the P.11 was launched into production, Romania showed interest in the design and had arranged to license-build it as the IAR P.11 (the Romanians even incorporated the P.11's tail unit in their later IAR 80 fighter aircraft design). The P.11 used an even more powerful engine than the P.7, a 800-horsepower Bristol Mercury IV, combined with an even more robust structure based on the P.7 design. The first P.11s became operational with the Polish Air Force in 1935 as the primary fighter. 

Model box art of the P.24 in Royal Hellenic Air Force colors
Buoyed by the success of the P.11 and its export to Romania, Jakimiuk developed the P.11 further into a variant intended for export, the P.24. Since the license for the Bristol radial engines prohibited export, the P.24 was based on the P.11 but incorporated a 900-horsepower French Gnome-Rhône Mistral radial engine which was a fourteen-cylinder two-row engine. In addition, the P.24 had a fully-enclosed cockpit and heavier armament that could include two 20mm cannons. Greece took delivery of 36 aircraft, Turkey took 60 (in fact the world's only surviving P.24 is in a Turkish museum), Bulgaria took 36 and Romania got 50 with 44 of them license-built by IAR. The P.24's performance was quite a leap from the P.11 thanks to its more powerful engine and the first variable-pitch three bladed propeller fitted to a PZL fighter design. Turkey's P.24s were flown until the late 1940s as training aircraft, some getting retrofitted with the Pratt and Whitney Twin Wasp engines used on the Douglas DC-3. Romania's P.24s protected the Ploesti oil installations at the start of Operation Barbarossa and flew ground attack missions until 1942. The Royal Hellenic Air Force was the only air arm to use the P.24 as its primary fighter type and it gave a good account for itself against the numerically superior Regia Aeronautica during the Italian push in Albania. By the time of the German invasion in April 1941, though, only five P.24s remained. 

Model box art of the P.50
Given the leap in performance of the P.24, you might be asking yourself why the Polish Air Force never operated it and stuck with the P.11. When the P.11 became operational in 1935, that was around the same time that the prototypes of the Messerschmitt Bf 109 (1935) and the Supermarine Spitfire (1936) first flew. It was pretty obvious to the Polish military command that the P.11s were quickly going to be come obsolete, so Jakimiuk broke from PZL tradition to design a much more modern fighter- a low wing monoplane fighter with an enclosed cockpit and retractable undercarriage, the P.50 Jastrząb or Hawk- it looked a lot like the Curtiss P-36 Hawk, though this is purely coincidental given that common problems in aviation design result in common solutions. Again using the Bristol Mercury engine, Jakimiuk's design was enthusiastically accepted by the Polish Air Force and ordered into production in 1937. The 800-horsepower Bristol Mercury VIII engine was ordered direct from the UK until license production could get underway in Poland. The second prototype P.50 would have an even more powerful engine, the Bristol Taurus with 1,150 horsepower with plans for a P.50 export variant with French Gnome-Rhône engines. The first flight was made in February 1939. The following prototypes and production standard aircraft were planned to have a cut down rear fuselage to improve rearward visibility during air combat. 

At the end of August 1939 on the eve of the German invasion, only the unarmed P.50 prototype was flying. The second prototype P.50 still had not received its Taurus engine and the third prototype was about 80% complete. In addition, airframe sections for four more P.50s were under construction. Poland fell to the Nazi onslaught in two days with the P.50s being captured and studied before being scrapped in 1940. The sole P.50 prototype was flown out in an attempt to escape, but ran out of fuel and crashed. Jakimiuk and his family managed to escape Poland during the invasion and his prior contacts with De Havilland proved fruitful as they arranged for him to work at their Canada subsidiary at Downsview north of Toronto. Rather amusingly, Jakimiuk, his family, and a team of engineers from PZL that he brought with him, were denied a permanent visa by the Canadian government as Ottawa bureaucrats demanded to know who was covering the Poles' travel costs from the UK to Canada. De Havilland guaranteed the travel costs for Jakimiuk and his family and his team of engineers as a gesture of thanks for the their advice on the DH.95 Flamingo transport back in 1937. In all, De Havilland covered the costs of travel and relocation for forty PZL engineers and their families to Canada to work at the Downsview facility. Many of Jakimiuk's colleagues would go on to to have illustrious careers in both the Canadian and American aerospace industry for years to come after the war. As for Jaki Jakimiuk, by the end of the Second World War he would become De Havilland Canada's chief designer and his experience with the PZL fighter line would prove indispensable as DHC made the transition from wartime production to peacetime civilian aircraft designs. 

But that's a story for a future blog article!

Source: Immortal Beaver: The World's Greatest Bush Plane by Sean Rossiter. Douglas & McIntyre Books, 1996, pp 17-23. Photos: Wikipedia, Wings Palette, Internet Modeler

21 July 2015

How a Lot of Airbus Jets Were Born on Boeing Wings

A340 fuselage barrel being loaded into 377SGT No. 3
With the formation of Airbus Industrie and the launch of the Airbus A300 jetliner, the different consortium partners finalized their workshare of the project- the tail section was the responsibility of the Spanish, the British were responsible for the wings, the Dutch fabricated all the moving surfaces of the wing, the Germans built the forward and aft fuselage along with the top section of the center fuselage, and the French were responsible for the nose, flight deck, control systems, the lower section of the center fuselage and final assembly of the A300. Splitting up the construction of a commercial aircraft in this manner wasn't necessarily new to the aerospace industry- after all, Boeing had about 65% of the Boeing 747 farmed out to various subcontractors with over 20,000 companies in just about every one of the fifty US states and some foreign nations. But what was novel in what Airbus was doing was that it was the very heart of the enterprise with the partner nations assuming near-equal risk. This would be how every Airbus jet would be built and each partner nation would build their sections to as near complete as possible. For Boeing, they retained oversight and control over what their 747 subcontractors would be doing and providing. For the A300, each Airbus partner wasn't overseeing each other- they were more or less having to trust that each partner would provide a finished product that met the specifications and could be easily integrated into final assembly in France. This required each firm to work in near-perfect harmony and coordination with the other consortium members. There was no margin for error- it has been said that if a Swiss watch were scaled up to the same diameter as the A300's fuselage, the tolerances on the A300 were much tighter than that of the Swiss watch!

Parts were designed in such a way to facilitate this process, but other steps were necessary for proper coordination. At the Hawker Siddeley plant in the UK that built the wings, for example, they had special jigs that the wings could be "plugged" into that replicated the fuselage center section that they would join up with in the final assembly hall in Toulouse. More difficult was getting each nation to adopt the same production techniques. During the early days, engineers at Airbus joked how easy it was to tell whether a particular join in the aircraft was done by the French or Germans. But it had to work and with great perseverance, the A300 was coming to shape. 

Surprisingly, in the early days of Airbus, the biggest problem they faced in getting the A300 into production was the logistics of having factories in France, Germany, Spain, Great Britain and the Netherlands all separated by significant distances. The straight line distance from Germany's Hamburg production facility to the final assembly hall in Toulouse was 900 miles. It was originally planned that all the large sections would be transported by sea- this was why the German Airbus facilities were in Bremen and Hamburg which had easy sea access and the Hawker facility had good road links to the port at Liverpool. Toulouse, however, is about 100 miles inland with no sea access. The original plan was to transport the fuselage and wing sections up the Garonne River from Bordeaux on the Atlantic coast. Because of the depth of the river and the size of the components, they would only be able to up about 50 miles from Bordeaux at which point the components were transferred to a road convoy- to minimize disruption along the route to Toulouse, it had to be done at night and numerous telephone poles, trees and power lines would have to be relocated. Some of the transport vehicles would be near 100-feet in length and it wasn't long before Airbus officials came to their senses and realized that this was a very inefficient and time-consuming process to get airframe components to final assembly. 

Airbus Skylink, Felix Kracht's solution for Airbus' logistical problem
The A300 production manager was a German engineer named Felix Kracht. Before joining the nascent Airbus in 1968, Kracht had worked on harmonizing production methods and standards on the Franco-German C160 Transall military transport program. About the time that the A300 program had been launched, Kracht was familiar with Aero Spacelines and its founder, Jack Conroy. Aero Spacelines was established by Conroy to convert Boeing 377 Stratocruisers into outsize cargo transports for NASA. Not only did ASI design and convert the aircraft, they also operated the aircraft as well. The first conversion was done in 1962 using a retired Stratocruiser and was called the Pregnant Guppy which transported both Titan II stages for the Gemini program and Saturn stages for the Apollo program. By 1970 a bigger and more capable Guppy had made its first flight- longer and more capacious than any of Conroy's other designs, the new Super Guppy Turbine (377SGT) was turboprop-powered. The first 377SGT made its first flight after conversion on 24 August 1970 and the second 377SGT first flew on 24 August 1972. By this point, however, ASI was in financial trouble and that's where Felix Kracht and Airbus stepped into the picture. He astutely realized its capacious fuselage and swing-nose loading were the perfect solution to the logistical problem of getting large airframe sections to Toulouse for final assembly. In 1970, Kracht had arranged for Airbus to purchase the first 377SGT with delivery in 1971. The purchase deal included a contractual commitment from ASI to build a second 377SGT as a back up for Airbus to serve as a back up for the first 377SGT. With ASI in dire financial straits in 1973 as the Apollo program was winding down, Airbus purchased the second 377SGT built. Plans then evolved once A300 production had been launched for a third and fourth 377SGT to be built for Airbus. By this point ASI was in no position to complete construction of two more aircraft, but they did complete sub-assemblies which were then completed in France. The third 377SGT first flew in 1979 and the fourth and final 377SGT first flew in 1980. 

Operating the Super Guppy fleet wasn't cheap, but in terms of time savings and efficiency, the cost was worthwhile compared to any sea/ground-based transport option. As the battle with Boeing heated up in the late 1970s, Boeing criticized what was called the Airbus Skylink program but Airbus responded by overlying a map of Boeing's subcontractors over a map of the Airbus partners to show the distances flown by the Super Guppies was shorter than the distances from Boeing's subcontractors to final assembly in Seattle. By the 1980s, though, the age of the Super Guppy fleet was becoming a significant cost center for Airbus. In 1991, the French company Aerospatiale and the German company DASA formed a joint enterprise to develop and build a replacement for the venerable Super Guppy fleet, ironically based on the A300. Construction of the Airbus Beluga began in September 1992 with the first flight taking place in 1994. A total of five Belugas have been built with the last one completed in 1999 which allowed for the retirement of the Super Guppy fleet. 

377SGT No. 4, now N941NA operated by NASA
Super Guppy No. 1 was retired in 1996 and resides at the British Aviation Heritage Museum at Bruntingthorpe awaiting proper restoration. Super Guppy No. 2 was also retired in 1996 and is on display at the Airbus facility at Toulouse and is under the care of the group Ailes Anciennes Toulouse ("Toulouse Old Wings"). The Musée de l'Air et de l'Espace at Le Bourget was offered Super Guppy No. 2 initially, but they had to decline on account of space considerations. Super Guppy No. 3 was retired in 1997 and is on display at the Deutsche Airbus facility at Hamburg Finkenwerder, Germany. Super Guppy No. 4, however, continues to earn its keep, but no longer for Airbus. In an International Space Station barter agreement, Super Guppy No. 4 was transferred to NASA in exchange for delivery to the ISS by the Space Shuttle components from the European Space Agency. Now with tail number N941NA, the NASA Super Guppy transported ISS modules destined for in-orbit assembly and currently transports launch payloads. 

As an interesting note on Super Guppy No. 4/N941NA- when Aero Spacelines was building the sub-sections for Airbus, the company found that there were no more spare Boeing 377 Stratocruisers that could be cannibalized to form the lower aft fuselage. The dismantled original Pregnant Guppy that first flew in 1962 was still available and was purchased for its lower aft fuselage which was incorporated into Super Guppy No. 4/N941NA. Now here's what's interesting- the Pregnant Guppy was converted from the third Boeing Stratocruiser prototype that made its first flight in 1948! That means that not just a significant portion of Airbus jets produced made their "first flight" on the third Stratocruiser prototype (so to speak), but so did some of the modules of the ISS. 

Further reading: 

Related reading:

American Airlines Picks the DC-10 (American's pick of the DC-10 is intertwined with the early history of Airbus)

Sources: Close to the Sun: How Airbus Challenged America's Domination of the Skies by Stephen Aris. Agate Books, 2002, pp 56-62. "All About Guppys" at www.allaboutguppys.com. Photos: Wikipedia, Airbus.

16 July 2015

The Unconventional Genius of Carl Norden

Carl L. Norden
After the Manhattan Project to develop the atomic bomb, the next biggest top secret defense program in the United States at the time was the development and production of the Norden bombsight. The Norden sights were used in all of the United States Army Air Forces heavy bombers (the Boeing B-17 Flying Fortress, the Consolidated B-24 Liberator, and the Boeing B-29 Superfortress) primarily and it was a Norden sight that bombardiers used to drop the atomic bombs on Hiroshima and Nagasaki that brought the Second World War to a close. Despite its crucial role in strategic bombing campaigns in both the European and Pacific Theatres, the Norden bombsight was a Navy program and every Norden sight used by the US Army Air Force had passed through the hands of Navy inspectors. How this state of affairs came to be is the story of how an unconventional but brilliant Dutchman, Carl Norden, came to be employed by the Navy prior to the start of the Second World War. 

Carl Norden was born on 23 April 1880 in Semarang, Java, in what was the Dutch East Indies (modern day Indonesia), the middle child of five siblings in a household with absent father. From a young age, his mother considered him the most reliable and responsible of his siblings- in a sense, he became the "man of the family". He had wanted to become an artist, but when his older brother decided to pursue an artistic career, Carl decided to pursue a lucrative career in order provide for his mother and his siblings, enrolling in the Federal Polytechnic Institute in Zurich, Switzerland and graduating in 1904 as a mechanical engineer. Although Dutch by birth, Norden's father was a naturalized Dutch citizen from German and Norden's own wife was from Austria. Norden's German ties dovetailed into his natural engineering and mathematical prowess- it was said that Carl Norden viewed everything in life in mechanical terms governed by mathematical formulas, the universe being nothing more than a great mechanical timepiece. After his graduation in 1904, he emigrated to the United States where he had a wealthy uncle who had made his fortune in the cotton business. Norden worked for a series of companies as a mechanical design engineer, but it was painfully obvious that he was difficult to employ as he was very much a prima donna. But there was no question of Norden's brilliant mind and after a series of employers over six years, he finally came to work for Elmer Sperry Sr. and his sons, Elmer and Lawrence at the Sperry Gyroscope Company. Norden's mechanical aptitude fit well into the work the Sperrys were doing for the Navy in developing gyroscopes to improve the accuracy of naval gunnery from moving ships. Norden's work with Sperry was invaluable for the company and Norden made many contacts within the Navy as a result. Norden tolerated Sperry as the work was interesting, but the relationship soured when, after solving the problem of gyroscopic oscillation, Norden got what he thought was an insulting $25/week raise as a reward. Norden quit and became a consulting engineer to the Navy, but it was the start of a feud between Norden and Sperry for years. Norden often dismissively told people Sperry "would patent gravity if he could" and Sperry for years tried to legally dispute many of Norden's later patents. 

In 1913, Norden set up shop near the Brooklyn Navy Yard and continued to work on the ship stabilization project for the Navy much to Sperry's chagrin. The Navy was enamored with Norden's genius and that relationship in large part protected Norden from Sperry's multiple legal challenges. With the progress on the ship stabilization project slow in coming, the Navy astutely put Norden's mind to work on other projects, starting the aerial gyroscopes for the aerial torpedo project as well as designing catapults and arresting gear for aircraft carriers. The arresting gear of the USS Lexington and USS Saratoga were designed by Norden himself on his dining room table!

At the time, the Navy was pursing a bombsight program as it felt that the best way to sink ships from the air was via high altitude level bombing. General Billy Mitchell's ship-bombing tests in the summer of 1921 against captured German warships convinced the Navy that it had to find a way to sink ships at sea. The Navy's Bureau of Ordinance (BuOrd) was responsible for the bombsight program and many different types, including some from Sperry, were tested. Officers with the Aviation Section of BuOrd came to know Carl Norden from his work on the aerial torpedo project as he had been consulted as an outside expert to evaluate Sperry's work (something which truly irritated Sperry to no end). They were impressed with the comments made in the reports and not knowing who Carl Norden was, found a report signed "Norden". A quick check of the Brooklyn telephone book and a few calls got the officers from BuOrd in touch with Norden who agreed to review the Navy's bombsight program. The gyroscopic stabilization work he had done for the ship and aerial torpedo project dovetailed neatly into the bombsight problem as Norden recommended that the bombsights be not only gyroscopically stabilized, but also connected to either an autopilot or pilot director so that during the bomb run, the bombardier was the one "flying" the aircraft. Eventually modifying existing bombsights turned out to be a failure and the BuOrd and Norden decided to start from scratch and create a whole new bombsight that would launch the Norden bombsight into aviation history. 

That's not to say that Norden's genius resulted in success. For most of the 1920s, many of the literally handcrafted Norden sights had dismal performance. But Norden wasn't one to give up and the Navy was an incredibly accommodating employer. Well aware of Norden's personality- they nicknamed him "Old Man Dynamite", they gave him tremendous latitude as long as he kept delivering results in the form of progressive improvements to his bombsight designs. Unlike most engineers, Norden did his own drafting. He didn't have an extensive engineering library, he preferred to work with his slide rule, a set of engineering tables and a few select references. He often stayed at his mother's home in Zurich, Switzerland, to ponder mechanical problems and develop solutions. His drawings and correspondence were then delivered to the US Navy by diplomatic pouch from US embassy in Switzerland. The State Department wasn't keen on this but high level pressure from the US Navy encouraged diplomatic officials to be as accommodating to "Old Man Dynamite" as possible. Sometimes it was his family he sent to Switzerland so he could be alone to solve some problems back in New York. Also unique to the Navy's relationship with Norden was that any patents were held by the Navy and classified as top secret. In this way, not only was Norden shielded from Sperry's legal challenges, but it also meant that the Navy didn't have to follow the prescribed competitive bidding rules to pay Norden for his work. Many of Norden's patents sponsored by the Navy from the 1920s and 1930s weren't even declassified until 1947! In contrast to the US Army Air Corps (forerunner of the US Army Air Forces) who held open competitive bidding in its own bombsight program and trialled bombsights from several different manufacturers, the Navy only did business with Norden and Norden alone. In fact, the Navy was Norden's only client! 

Theodore Barth at a circus held for Norden employees
As work on the Norden sights continued in the 1920s, BuOrd recommended that Norden partner up with an engineer to start moving the bombsight project towards mass production. Knowing Norden well, the Navy partnered him up with a former Army colonel and engineer by the name of Theodore Barth and it was the start of a very close relationship between the two men for many years. Norden's own children regarded Barth as a secondary father figure in their lives, so close was Barth to Norden. It was Barth who was tasked by the Navy to take Norden's designs and put them into production. Compared to Norden, Barth was very personable and possessed quite a bit of business acumen as well- Norden may have been the brains of the operation but it was Barth who made everything work and kept everyone happy. During the Second World War, Barth took it as his job to take care of all of the employees that were building bombsights. He often gave away baseball tickets and even rented out Madison Square Garden for a circus just for Norden's employees. 

From the time Norden was contacted by the Aviation Section of the Bureau of Ordinance to the delivery of the first production bombsight to the fleet, the Norden Mark XI, nine years had elapsed. During those nine years Norden progressively refined the design of what was essentially a clocklike analog computer that was gyroscopically stabilized and linked to the autopilot. The Navy, though, did hedge its bets just a bit- during that time it had contracted with General Electric for a back up bombsight design called "Scheme B" or the Mark XIII. After three years, the Navy found the GE bombsight was woefully inferior to Norden's designs and canceled "Scheme B". 

Norden M-1 bombsight
By the early 1930s, the US Army Air Corps became aware of the Norden program and was keen to get its hands on the bombsights for its own testing. The head of the Army Air Corps, General Henry "Hap" Arnold (who would head the USAAF during the Second World War), was shocked to hear of the working arrangement between the Navy's BuOrd and Carl Norden, from Norden not even being a US citizen to the fact that Norden did a lot of his work abroad in Switzerland and then sent drawings back via diplomatic couriers to New York City for Theodore Barth and Navy officials to review. The Navy wasn't about to change the way it did business with Carl Norden to assuage General Arnold's concerns, though. It basically came down to something along the lines "If you want Norden bombsights for Army bombers, this is the arrangement you have to live with!". As a modest concession, though, the Navy had the FBI provide a security detail for Norden and agents were planted in Norden's production facilities in New York City to root out any foreign spies. At all times, at least two armed agents were with Norden at all times. There is an apocryphal story that when Norden wasn't getting his way with the Navy, he'd insinuate he'd leave the United States and go to work for the British. He would later remark it was empty threat "As no self-respecting Dutchman would ever work for the British!"

By 1928, Norden was at work at a massive improvement to the Mark XI sight called the Mark XV. He delivered the Mark XV prototype to BuOrd in 1930 and it was this sight that pretty much ended the GE alternate bombsight program. The bombsights that came from the Mark XV design were known as the Norden M-series sights and those would become standard on American heavy bombers.  By this point, however, the Navy was drifting away from relying on high altitude level bombing at sea as dive bombing was explored by units in the fleet. But the arrangements between the Navy and Carl Norden remained with his New York City factory essentially being a Navy factory! By 1934, Norden's bombsights became the standard for the Army Air Corps, first being installed on Martin B-10s. It's estimated that approximately $1.5 billion was spent on the development and production of Norden bombsights. 

Carl Norden was passed away in 1965 in his beloved Switzerland. His company lived on as Norden Systems to be acquired by Westinghouse which was in turn acquired by Northrop Grumman. Norden and Barth also set up a second company called Barden to manufacture bombsight components- Barden is still  around today, fabricating ball bearings for a variety of industries including aerospace. Carl Norden was inducted into the National Aviation Hall of Fame in 1994. 

Source: America's Pursuit of Precision Bombing, 1910-1945 by Stephen L. McFarland. Smithsonian Institution Press, 1995, pp 45-76. Photos: Norden Systems Division via Stephen L. McFarland's book, Wikipedia

11 July 2015

The Rocky History of Ariana Afghan Airlines

Ariana's logo- note the use of the Pan Am font
Prior to the Second World War, air services to Afghanistan were adventurous to say the least, given the inhospitable terrain of the area. Most air links to South Asia of the day that connected the region to Europe passed via India and were controlled by primarily the British. The first air links to Afghanistan, however, came by way of the Soviet Union starting on 14 September 1926 when the Russian airline Dobrolyot connected Kabul to the other Central Asian cities under Soviet control with Junkers F13 monoplanes. Dobrolyot was founded in 1923 to develop air services in the Soviet Union and in 1932 it was Dobrolyot that formed the nucleus of a new airline, Aeroflot. Dobrolyot's air services to Kabul continued until the outbreak of the Second World War. Interestingly enough, Dobrolyot was not the only foreign airline active in Afghanistan in the interwar period- DLH (Deutsche Luft Hansa, predecessor to today's Lufthansa) also opened air services to Afghanistan. At the time, DLH was looking to extend its route network to China where there were substantial German business interests. However, remaining bitterness from the First World War stymied DLH's attempts to open routes to China via India, so going through Afghanistan was seen as a short cut around British influence in the area. DLH extended its network eastward from Istanbul to Baghdad in October 1937 and then extended again from Iraq to the Iranian capital of Teheran in April 1938. Two weeks later, DLH extended its network again, this time connecting the Afghan cities of Kabul and Herat via Teheran and at the time, it was the furthest corner of DLH's airline network. Services ended abruptly, though, in August 1939 on the eve of the outbreak of the Second World War. 

Air services to Afghanistan were spotty at best and ad hoc for the duration of the Second World War  and aside from a small air mail service using Hawker Hart biplanes, it would be an American businessman in India who would forge new air links into Afghanistan again at the end of the war. New York native Peter Baldwin had served with the US Army Air Force in India during the war and returned in 1945 leading a US government mission to oversee the disposal of surplus USAAF aircraft in the region. His job finished, he elected to stay in India and in 1947 formed a company in Bombay (Mumbai today) for the sales of light aircraft and airport equipment. By 1950, he had his own fleet of thirteen Douglas DC-3s that he was flying all over the region on charter flights all over India, the Middle East and as far as Africa. His small charter operation even operated Hajj flights to Mecca. It was in this capacity that he came into partnership with the Afghan government. 

The DC-3 services were a boon to a country without railroads.
In 1951, the Kabul government established a branch of the Royal Afghan Air Force that was tasked with civil aviation development with Colonel Gulbar Khan as the head of what was called the "Hawabazi Mulki". Colonel Khan worked out a partnership with Peter Baldwin to form a new Afghan airline which was established on 27 January 1955 as Aryana Afghan Airlines in Kabul with Peter Baldwin holding 49% ownership of the airline and the Kabul government owning 51%. I haven't been able to determine if the airline's first three DC-3 aircraft were from Baldwin's charter operation, but it would make sense given his signifcant ownership in the new venture. The first services were launched at the end of 1955 connecting Kabul to Mazar-i-Sharif in the north near the Soviet border via the city of Kunduz. What had taken a week on the region's poor roads now only took three hours. 

During the Pan Am years, the Ariana chief pilot was a Pan Am pilot
On 27 June 1956, the Kabul government signed an air transport and development agreement with the United States. At the time, both the Soviet Union and the United States were eager to get Kabul's business and the Afghans astutely played both sides off each other to get economic development agreements. The air agreement with the United States included Pan American buying out Peter Baldwin's interest in Aryana. As a result, Pan Am become responsible for all operational and technical matters and also changed the spelling of the airline's name to Ariana, ostensibly to eliminate any possible references to the word "Aryan" that had been corrupted by the Nazi regime during the Second World War. On 3 June 1956, an Ariana Douglas DC-4 with an all-Afghan crew trained by Pan Am departed New York for Kabul to begin Hajj flights to Mecca. The DC-3s were used for internal domestic services that connected Kabul to Herat, Kandahar, Kunduz, Mazar-i-Sharif, and Maimana. New Delhi was connected to Kabul via the Indian city of Armistar and Karachi, the Pakistani port city, was connected via Kandahar. The DC-4 was used to connect Kabul to Teheran, Beirut and Damascus via Kandahar where American economic development funds were used to build a modern airport and terminal facility. 

Ariana launched services to Europe on 11 September 1959 on what they called the "Marco Polo Route" which used the DC-4 on services to the Turkish capital of Ankara via Beirut. The flight then continued on to Prague and then terminated in Frankfurt. The airline had to replace its DC-4 with a larger DC-6B as adventurous European tourists began to fly the "Marco Polo Route" to Kabul. The airline soon found that it was more profitable for the DC-6B services to bypass Kabul and instead fly Kandahar to New Delhi. Political instability in the region in the 1960s resulted in the termination of services to Karachi and the services that connected Frankfurt to New Delhi could only be flown twice a month- soon after, European services were cut altogether with Ariana's westernmost destination being Beirut by 1962.

Ariana Afghan 727-200
Ariana was near dormant when American development funds arrived again in 1963. This was a time of superpower rivalry and Afghanistan was no different than any other non-aligned nation of the time that had both American and Soviet interests competing for influence. Ariana got an extremely low-interest loan (it was pretty much a gift) that included a second Douglas DC-6 and two ex-Pan American Convair CV-340s to replace the DC-3 on the domestic services. A third CV-340 was purchased from Allegheny Airlines and this allowed a return to Karachi via Kandahar as diplomatic relations between Pakistan and Afghanistan improved. In July 1965, Ariana opened DC-6 services to the Uzbek capital of Tashkent in a pooling agreement with Aeroflot and in the following month, services to Europe resumed with DC-6 services from both Kabul and Kandahar to London Gatwick, stopping only in Beirut and Frankfurt. In April 1968, Ariana got its first jet equipment with a Boeing 727-100 which replaced the DC-6s on the European services. The route to London was reconfigured to route via Teheran, Istanbul and Frankfurt, but as Ariana had no fifth freedom rights, only Kabul/Kandahar-bound passengers could be boarded at London Gatwick. That first 727 crashed in dense fog on approach to London on 5 January 1969, but two more 727s were added- the first a lease from World Airways that was bought outright and a second purchase from Executive Jet Aviation, arriving in 1971. 

Ariana Afghan Airlines Tu-154- note the continued use of the Pan Am font!
The domestic routes of Ariana were spun off under a subsidiary airline called Bakhtar Afghan Airlines. This was a political move more than anything else as some Afghan officials wanted to limit US influence in the northern tier of cities along the Soviet frontier- this was accomplished by cutting Pan Am out of Bakhtar's operations. In 1973, Bakhtar took delivery of three Yakovlev Yak-40 trijets, becoming one of the few non-Soviet client state customers for the 28-seat feeder jet. Pan Am was still needed in the Ariana international operation, though, as Pan Am sold Ariana a Boeing 720B on very generous terms (again, it was pretty much a gift) in May 1973. That year, though, on the heels of a severe drought 1971-1972, Prime Minister Mohammed Daoud Khan seized power in a non-violent coup, deposing King Zahir Shah and ending the Afghan monarchy. A republic was proclaimed to institute economic reforms but only political instability was established as various Afghan leaders relying on tribal loyalties began to vie for control of the country. A series of coups followed starting in 1978, but despite this, Ariana launched Douglas DC-10 Series 30 services with a single aircraft in October 1979 on its services to London which could now be served nonstop. On 24 December 1979, the Soviet Union invaded Afghanistan which for all intents and purposes ended Ariana's operations. The two 727s and DC-10 were parked and eventually sold off under Soviet pressure by 1985. Its regional subsidiary, Bakhtar, took over Ariana's operations with two Tupolev Tu-154M aircraft starting in 1987, but the following year the Ariana name was resurrected and Bakhtar's domestic routes and operations folded into Ariana. 

Ariana's sole Douglas DC-10
The country descended into outright civil war following the Soviet withdrawal in 1989. Communist President Najibullah's regime only lasted to 1992 and with the Taliban takeover in 1996, worldwide sanctions crippled what was left of Ariana's operation. Pakistan set up a temporary maintenance base for the airline in Karachi, and only Dubai remained as the airline's only international destination. During the Taliaban's regime, Al-Qaeda operatives were given Ariana identification to allow them to move arms, personnel and opium shipments between Dubai and Pakistan. There were indications that Russian arms dealers were operating Ariana during this period. By November 2001, only a month before US-led forces toppled the Taliban regime, Ariana was finally grounded for good. Ariana would be resurrected in the post-Taliban era, but that's a subject for another blog posting in the future!

Source: Airlines of Asia Since 1920 by R.E.G. Davies. Palawdr Press, 1997, pp 84-88. Photos: Marc Riboud/Magnum Photos, Wikipedia, National Archives

06 July 2015

The Origins and Development of the American Escort Carrier

The USS Long Island as built, the first escort carrier
At the start of the Second World War with the German invasion of Poland in September 1939, the Kriegsmarine had fifty-seven U-boats in its fleet, but of those fifty-seven submarines, only twenty-two of them were suitable enough for carrying out combat patrols in the Atlantic and that small group consisted of the 626-ton Type VII boat and the larger 1,032 ton Type IX boat.  The Type VII was the most common U-boat used in the Battle of the Atlantic and with 703 hulls constructed, was the most widely built submarine class in naval history. The larger Type IX submarine was designed for extended long range patrols but lacked the maneuverability of the Type VII. Approximately 283 hulls of this larger class were built during the Second World War. Prior to the onset of the war, the head of the U-boat force, Rear Admiral Karl Doenitz, had stated that he would need at last ninety operational boats for the Atlantic at the start of hostilities and that eventually 300 would be needed to guarantee that he could choke off Great Britain's Atlantic supply routes. Fortunately for the Allies, Hitler didn't believe that the war would take long and dragged his feet on authorizing rapid expansion of the U-boat force for some time. The Atlantic U-boat menace is the context to understand the development of the escort carrier- in fact, as it would turn out, the escort carrier was one of the keys to victory in the Battle of the Atlantic. 

Led by the British construction of the HMS Argus which was commissioned in 1918 as the world's first aircraft carrier with a full-length deck (thereby setting the pattern of the aircraft carrier configuration) after conversion from a partially completed ocean liner, the United States Navy had the collier USS Jupiter converted to the first American aircraft carrier, the USS Langley, which was commissioned in 1922. Compared to the large fleet carriers that would become famous in the Second World War, both the HMS Argus and the USS Langley were much smaller vessels with the Argus coming in at 15,775 tons and the Langley at 11,050 tons. But both navies gained valuable experience in operating the ships, the US Navy in particular using the Langley to fine tune procedures for high tempo flight operations. The interwar period was a time of transition for both the US Navy and the Royal Navy as they transitioned from big gun warships to aircraft carriers- during the First World War, the first aircraft carrier in naval history, the HMS Furious, had started out as a cruiser converted with a partial flight deck before getting upgraded to a the pattern set by the HMS Argus with a full length deck. During it's time with a partial flight deck, though, the Furious did retain its aft gun turret, leading to some discussions in the Royal Navy about hybrid cruisers- vessels that had partial flight decks with cruiser guns. The ideas persisted into the 1920s and with the limits on battleship and aircraft carrier tonnage by the 1922 Washington Naval Treaty, the ideas of small aircraft carriers arose as a way of making better use of the allowed tonnage. A loophole in the treaty allowed the United States a chance to use up to 25% of its allotted cruiser tonnage for conversion to small aircraft carriers, but this was an idea that many "Big Gun" admirals were reticent to pursue. 

Bruce G. Leighton, early escort carrier advocate
In 1927, USN Lieutenant Commander Bruce G. Leighton wrote an influential paper on light carriers- he had presciently described roles for such carriers to include antisubmarine warfare, supporting larger fleet carriers, scouting and reconnaissance and support of amphibious landings while larger carriers could be freed up to hunt down the enemy's capital ships. He was also motivated by a concern that the loss of a large fleet carrier would be a bigger blow to the Navy's strength than the loss of a smaller carrier based on a cruiser hull. At the time of Leighton's paper, the USS Lexington and the USS Saratoga had just become operational and even though both vessels were much larger and more useful operationally than the USS Langley, they were still just the second and third aircraft carriers in the US fleet. 

With the clouds of war looming on the horizon and Japan pursuing an aggressive expansionist foreign policy in the Western Pacific, in 1935 the US Navy's Bureau of Construction and Repair had been considering conversion of ten fast passenger liners into light carriers. Conversion of an existing hull was believed to be the most expeditious way to get hulls into the fleet. The plans for light carriers might have died off had it not been for men like John S. McCain, the captain of the fourth US aircraft carrier built, the USS Ranger (the Ranger was first US carrier built from the keel up as an aircraft carrier; McCain was the grandfather of Arizona Senator John McCain). He and others in the fleet had wanted up until 1939 approximately eight "pocket-sized" aircraft carriers based on cruiser hulls that could act as outer defensive screens for the larger fleet carriers. The outbreak of the war in Europe furthered ideas of small aircraft carriers in the US Navy as observers watched the British battle the U-boats that were menacing their trans-Atlantic supply lines. Originally the USN thought that small aircraft carriers might have a dual role in providing air cover to the convoys in the Atlantic as well as delivering much-needed Lend-Lease aircraft to the Royal Air Force. As it would turn out, the cause of what would become the escort carrier got its biggest boost in October 1939 from President Franklin D. Roosevelt. He was a lifelong enthusiast and student of naval history and served as Assistant Secretary of the Navy from 1913-1918 under President Woodrow Wilson. Well-versed in naval affairs, Roosevelt instructed the US Navy to procure a merchant ship for conversion to an aircraft carrier. The ship was to displace 6,000 to 8,000 tons and have a speed of 15 knots and operate a unique air wing made up of either 12 helicopters or autogyros. The vessel would act as a convoy escort and perform antisubmarine warfare missions- the helicopters or autogyros wouldn't carry weapons, but use smoke bombs to mark U-boat locations for attack by destroyers.

Discussions with the Chief of Naval Operations, Admiral Harold Stark, in the weeks following Pearl Harbor led to the decision to obtain two diesel-powered C3-class merchant vessels from the Maritime Commission. The C3 class was designed by the US Maritime Commission as a 492-foot (150m) general purpose vessel that could be easily modified to a variety of roles. Helicopters and autogyros were ruled out as it was felt fixed-wing aircraft were more flexible and capable compared to the rotary winged aircraft of the day. This dictated the need for a full length flight deck. The Navy told the President that conversion to an escort carrier would take 18 months, but to Roosevelt, this was unacceptable. The speed of conversion was essential. He told Admiral Stark that the conversion should take no more than three months. At end of January 1940 two vessels were secured from the Moore-McCormick Line, the Mormacmail and the Mormacland. One ship after conversion would go to the US Navy and the other ship after conversion would go to the Royal Navy. The only organic air cover the British had at the time for the Atlantic convoys were Hawker Sea Hurricanes installed on CAM ships- catapult aircraft merchant ships. It was a one-way trip for the pilot who had no means of recovery other than ditching alongside a ship. Wholly unsuitable for antisubmarine warfare, the CAM ships were really geared towards going after the long-range Focke Wulf Fw 200 Condor maritime patrol aircraft that scouted the Atlantic for the U-boat fleet.

On 2 June 1940 just a few days before Roosevelt's three month deadline, the Mormacmail's conversion to an escort carrier was completed and she was commissioned as the USS Long Island at Newport News, Virginia and designated APV-1 but was soon changed to AVG-1 (Aircraft Escort Vessel). The designations changed two more times during the war as the value of the escort carrier was proven, to ACV (Auxiliary Aircraft Carrier) in August 1942 to CVE (Escort Carrier) in July 1943. As built, the USS Long Island was 492 feet (150m) and displaced 13,500 tons and could make 16.5 knots. The original flight deck was only 362 feet with the bridge below the forward edge of the flight deck. Testing showed the need for a longer flight deck, so in the summer after her commissioning the carrier went back into the yards to have a proper full length flight deck. There was one elevator aft and a single forward catapult on the port side. The opportunity was taken during the extension of the flight deck to make other improvements and when she came out of her refit, the ship now displaced 14,953 tons and was faster with a speed of just over 17 knots.

HMS Archer- note the small island not present on the Long Island
The Mormacland was converted a similar configuration but had a small island on the starboard side. She was transferred to the Royal Navy in November 1941 to become the HMS Archer. Despite the getting the second escort carrier built in the United States, the Royal Navy did set out to build an escort carrier of their own with the conversion of the German merchant vessel Hannover to become the HMS Audacity, commissioned in June 1941 to become the first British escort carrier with the HMS Archer as the second such ship. Compared to the USS Long Island and the HMS Archer, the HMS Audacity was very small escort carrier with a displacement of only 6,000 tons with an air wing of just six aircraft. The two escort carriers were a boon to British convoy operations and the Royal Navy ordered five more escort carriers from the United States based on the C3 class merchant vessel hull and based on the USS Long Island with further improvements. These four ships had a 440-foot flight deck and a small island on the starboard side (which the USS Long Island lacked)- they became the HMS Avenger, HMS Biter, HMS Dasher, and the HMS Charger. The last ship of the group was returned to the US Navy in 1942 and became the USS Charger which remained on the US East Coast as a training carrier.

USS Bogue
Much like how the USS Langley was used primarily for testing and experimentation, so too was the USS Long Island in its early career as the first American escort carrier. With the entry of the United States into the war in December 1941, Admiral Doenitz's U-boat fleet began to prosecute its attacks on the US East Coast with 400 ships sunk just in the first six months following Pearl Harbor. With the utmost urgency, a new class of escort carrier was ordered into production based on the experience with the USS Long Island. These vessels were converted from twenty four C3-class hulls as the Bogue-class. Because the Long Island and the first British escort carriers were diesel powered, they were thought to be too slow based on operational experience and the Bogue-class carriers would have steam turbines to drive them to 18 knots. The new escort carriers had a flight deck 442 feet long by 80 feet wide, bigger than the Long Island's flight deck. A single catapult was fitted on the forward port side but the ships had a larger hangar deck and two elevators instead of the Long Island's single elevator. A small island was located on the starboard side as well.

USS Sangamon
Of the twenty carriers based on C3-class hulls that became to Bogue-class, ten of them went to the Royal Navy. The new ships could carry twice the fuel of the Long Island/Archer-class ships and had an improved compartment layout in the hull. As the ships were four feet lower than the Long Island/Archer, they also had better seakeeping qualities. Since the 1942 escort carrier program called for twenty-four ships and only twenty C3-class hulls were available, four Cimarron-class fleet oilers were converted to escort carriers to become the Sangamon class. As these ships were based on larger hulls, they were longer at 553 feet with 23,250 tons displacement and could carry two squadrons of aircraft. Launched originally with just a single port side catapult, the four ships of the Sangamon class got a second catapult on the starboard side in 1944. Being former fleet oilers, the Sangamon class carried a significant amount of fuel which could also be used to top off the escorting destroyers in the task force. They were more stable at sea than the Bogue-class and could make 19 knots. The four ships of this class were the USS Sangamon (CVE-26), USS Suwanee (CVE-27), USS Chenango (CVE-28) and USS Santee (CVE-29). The Navy wanted more Sangamon-class carriers, but fleet oilers were also in demand for underway replenishment of the carrier battle groups in the Pacific.

Aware of the shortage of hulls for conversion to escort carriers, American shipbuilding magnate Henry J. Kaiser had proposed to President Roosevelt in 1942 the construction of an escort carrier design capable of 20 knots in quantity production from his shipyards which were turning out Liberty cargo ships at an impressive rate. Using prefabricated sections and mass production techniques used on the Liberty ships, the Casablanca-class escort carriers would become the most produced aircraft carrier class in naval history with fifty carriers built between July 1943 to the last Casablanca-class built in July 1944, an astounding achievement for the American wartime shipbuilding industry. The ships were built in Vancouver, Washington, and then delivered to Astoria, Oregon for final fitting-out before commissioning.

Schematic of the USS Casablanca
The Casablanca-class (the lead ship, USS Casablanca, was designated CVE-55) were 498 feet long with a 477-foot long by 80-feet wide flight deck that had two elevators and a single port side catapult. The engines were spaced apart to prevent a hit from taking out the engine room and the hangar deck was quite wide for an escort carrier. They were also the first all-welded carriers which made them lighter at 10,900 tons displacement but this gave the Casablanca-class superb maneuverability. Despite the quantity production and design features, the Casablancas weren't as good as the Sangamon-class carriers and the Navy insisted on something better if not as good as the Sangamon class. This resulted in the ultimate and final escort carrier class of the war, the Commencement Bay class.

USS Commencement Bay, the ultimate escort carrier
Based on all the operational experience of escort carriers so far, the Commencement Bay class ships were based on an improved Sangamon-class layout but longer with a length of 577 feet and a displacement of 24,900 tons. The flight deck was much stronger to operated heavier aircraft and the two elevators also operated faster to speed flight operations. Two forward catapults were standard with a bigger island as well. The ships could make 20 knots and had the heaviest defensive anti-aircraft armament of any escort carrier of the war. The lead ship, the USS Commencement Bay (CVE-105) was commissioned on 27 November 1944. Thirty-three ships were ordered but only nineteen were completed by war's end. Two of the completed carriers went straight into mothballs after completion. While the Commencement Bay-class carriers didn't see as much action as their predecessors, several of the ships did go on in the postwar period to become the first helicopter assault carriers and served until the arrival of the Iwo Jima-class LPH carriers in the 1960s.

Source: Hunter-Killer: U.S. Escort Carriers in the Battle of the Atlantic by William T. Y'Blood. Bluejacket Books/Naval Institute Press, 1983, pp 11-26. Photos: US Navy, National Archives, Wikipedia.