29 September 2015

The Cheapest Aircraft of the Second World War: The Focke-Achgelis Fa 330

Poor quality video of the Fa 330 operating from a U-boat (YouTube)

Earlier this month I had written about the aircraft types that were operated off submarines in the First World War, albeit on a very limited operational basis, and some designs that never quite made it to sea. In the interwar period, there were several experiments and attempts at aircraft operations from submarines- some of which will be future topics here at Tails Through Time- but none ever really evolved into a useful operational system. As is often the case in wartime, the pressures and operational needs of combat sometimes rekindle old ideas and this certainly the case for the German Kriegsmarine's Ubootwaffe (U-boat arm) in the Second World War. The initial plans were for a light seaplane from the Arado Flugzeug Werke designated Ar 231. Arado had built observation floatplanes for the larger surface combatants of the Kriegsmarine and in 1940, they were issued a contract for six "U-Bootsaugen" or "submarine eyes". The Ar 231 was the result and it was a single seat high wing monoplane with a 160 hp six-cylinder engine. The wings folded back over the fuselage and the entire aircraft could fit into a container only six feet in diameter. However, sea trials showed the little floatplane couldn't take off in winds greater than 20 knots and much like the problems faced in 1917, only the calmest of sea states was needed for safe flight operations- this was an unrealistic expectation for the planned operational arena for the U-boats, in the harsh North Atlantic interdicting convoys bound for Great Britain from the United States. The idea for the "U-Bootsaugen" was quietly canceled with the Ar 231 fading into the footnotes of aviation history. However, following the entry of Japan into the Second World War after its attack on Pearl Harbor, the directive came down for the Kriegsmarine to find a way to join forces with the Imperial Japanese Navy. In the same year that IJN submarines began operating in the Indian Ocean interdicting British shipping, the idea was passed to the Kriegsmarine in December 1942 to base U-boats in Japanese occupied Malaya and the East Indies. A new U-boat variant based on the large ocean going Type IX submarine, the Type IXD2, was on the drawing boards at that time as an ideal submarine for what the Kriegsmarine called the "Monsun Gruppe" which were U-boats based at Penang in Malaya. 

The Fa 330 at the RAF Museum in Cosford (Wikipedia)
On the broad and calmer Indian Ocean (at least on the trade routes from Africa to Australia), the Kriegsmarine once again issued a limited requirement for some means to extend the visual range of a surfaced U-boat for targets of opportunity on the cruises around the Cape of Good Hope to Penang and back. Simplicity and ease of use were paramount, mindful of past pitfalls with operating aircraft from submarines had shown. The unique demands were met by one of the most unique aircraft of the Second World War, if not the simplest and cheapest, the Focke-Achgelis Fa 330. Heinrich Focke had founded Focke-Wulf in 1923. In the 1930s, Focke-Wulf had license built Juan de la Cierva's autogyro designs and from that experience, Heinrich Focke designed the Fw 61 helicopter. However, in 1936, he was ousted from Focke-Wulf. Several references indicate it was because he was considered politically unreliable the the Nazi regime, but in all likelihood it was to get him out of the way so that Focke-Wulf's production capacity could be used to build more Bf 109 fighters from his rival, Willy Messerschmitt. Despite this, the German Air Ministry was impressed with the Fw 61 which the German pilot Hanna Reisch had ably demonstrated by flying the helicopter indoors. They encouraged Focke to start a new company devoted to the development of his true interest, vertical flight. He teamed up with his helicopter test pilot, Gerd Achgelis (he flew the Fw 61 on its maiden flight in 1936) to start Focke-Achgelis and it was this outfit that created the Fa 330 to meet the Kriegsmarine requirement for an observation aircraft of utmost simplicity for use by the submarines of the Monsun Gruppe

Lacking its own power plant, the Fa 330 was really a gyro kite. It had a three-bladed 24-foot rotor and when fully assembled, the Fa 330 weighed only 180 lbs. The main body was essentially an upright welded steel tube to which the rotor was attached at the top. A longitudinal tube of smaller diameter was attached to the bottom to which the single seat, controls, tail surfaces and outrigger skids were attached. Each of the major components attached together with simple spring loaded pins which also made for easy disassembly. Two vertically-oriented containers attached to the conning tower housed the parts. With each rotor blade 12 feet long, that dictated the maximum depth of each storage compartment. Four men could assemble the Fa 330 in only 3 minutes in a reasonable sea state. A platform sat on the aft part of the conning tower where the Fa 330 was launched and recovered. With the pilot/observer ready, the U-boat would turn into the wind as 20 mph was needed to get the Fa 330 gyro kite airborne as the pilot used his controls to tilt the rotor head back to "catch the wind" like a kite with a steel cable which also carried a telephone line to allow the pilot/observer to communicate with the submarine's bridge. The operating speed was usually about 25 mph but the Fa 330 could stay airborne with as little as 17 mph of forward speed by the U-boat. Typical operating altitudes were between 200 to 500 feet, though in calm weather, the Fa 330 could be flown up to 1000 feet. In good visibility, this extended the U-boat's visual horizon out from the usual 12 miles to 50 miles. At an altitude of 600 feet, the visual horizon was 31 miles. Even at minimum operating speed, the Fa 330 could fly 200 feet up and that still gave the U-boat captain a visual horizon of about 20 miles. The Fa 330 was recovered by simply winding the cable back in until the Fa 330 could alight on the conning tower platform. Though Focke-Achgelis designed the Fa 330, it was built by another company, the Weser Flugzeugbau.

Model kit box art showing an Fa 330 being deployed by a U-boat (Mirage Hobby)
Pilot/observers were trained to fly powered gyrocopters at the French Aeronautical Experimental Establishment outside of Paris. Training on the Fa 330 itself was carried out inside a large wind tunnel with more advanced training taking place with the Fa 330 being towed by trucks on a runway before moving to being towed to higher altitudes by a gyrocopter. A proposal was floated to put a 60 hp engine on the Fa 330, but it never advanced far with the Kriegsmarine. About 200 Fa 330s were built. At sea, the pilot/observer was in an unenviable position should he have spotted a warship as that would have meant an immediate crash dive by the U-boat. If this were to happen, the pilot was to activate his escape mechanism which severed the rotor blades get them away from the pilot who then dropped away from what was left of the Fa 330, his parachute ripcord being pulled automatically by the departing blades as they fell away. That left the pilot to float down to the ocean and hope to be picked up when the submarine resurfaced. It's not known what happened to most Fa 330 pilot/observers, though Royal Navy patrols in the Indian Ocean did come across floating parts from the Fa 330. 

Only the U-boats with Monsun Gruppe in the Indian Ocean used the Fa 330 as the Allied air threat in the Atlantic was too great. Only one sinking is known to be attributed to Fa 330 operations when U-177 used its gyro kite to assist with the interception and sinking of the Greek steamer Ethalia Mari on 6 August 1943. Details of the use of the Fa 330 operationally are scant on account of so few U-boats surviving the war. Several U-boat captains, however, believed using the Fa 330 was too risky which may have ultimately prevented its more widespread use. The Allies found out about the Fa 330 after studying the submarine U-852 after it had run aground on the coast of Somalia after an air attack. While not impressed with its capabilities, they were suitably impressed with its simplicity and ease of use. 
The L-3 Valkyrie Virtual Mast unmanned gyro kite (Popular Science)
Interestingly in 2013, the defense company L-3 proposed a re-imagination of the Fa 330 concept with their Valkyrie "Virtual Mast" in which a carbon fiber gyro kite would carry aloft an electro-optical/IR sensor as high as 5000 feet on a steel cable for ships at sea. 

Sources: Strike From Beneath the Sea: A History of Aircraft-Carrying Submarines by Terry C. Treadwell. The History Press, 2009, pp 103-109. The Smithsonian National Air & Space Museum.

24 September 2015

The Ultimate Superfortress: The B/RB-54A

Concept art of the B/RB-54A in flight
(Boeing Historical Archives)
During the Second World War Boeing worked extensively on further improvements to the B-29 Superfortress. The most important of these improved variants was the B-29D that involved swapping out the Wright R-3350 radial engines with the more powerful Pratt & Whitney R-4360 Wasp Major radial engine. In July 1945 the USAAF signed a contract for 200 B-29Ds, but with the end of the war and the rapid postwar demobilization, the B-29D contract was canceled. With the creation of an independent United States Air Force in 1947, there was a need for interim bombers pending the arrival of more advanced jet bombers. The USAF was already getting the Convair B-36 which took on the mantle of the heavy bomber, but the USAF also wanted the B-29D which would be redesignated as a medium bomber. The USAF had the B-29D redesignated as the B-50 to avoid the appearance of ordering a "wartime" bomber. Making its maiden flight on 25 June 1947, the B-50 Superfortress would eventually result in 320 examples of all variants produced.

Boeing, however, was working on an even more powerful and longer-ranged development of the B-50. Designated the B-50C, this evolution into the ultimate Superfortress was designed to extract as much speed and performance as was possible using a new version of the Pratt & Whitney R-4360 Wasp Major engine that added what was called a "variable discharge turbine" (VDT) to the engine. The standard Wasp Major used on the B-50 developed approximately 3,500 horsepower and a Wasp Major with a VDT could easily produce 4,000 horsepower, making it one of the most powerful production piston engines in the world.

The Wasp Major VDT
(from the Engine History website)
The VDT consisted of two General Electric CHM-2 turbosuperchargers that collected the hot exhaust gases from the 28 cylinders of the Wasp Major. A portion of the hot gases were diverted through an intercooler to provide turbosupercharging at high altitudes. The bulk of the hot gases went through the CHM-2 turbines and were exhausted out a variable area nozzle that resembled a set of eyelids. By adjusting the size of the nozzle, jet thrust could be achieved that had the potential to add as much as 15% to the speed of the B-50C over the production standard B-50. The Wasp Major VDT was already flying at this point on the Republic XF-12/XR-12 Rainbow long range reconnaissance aircraft. 

The scope of the changes needed to for the B/RB-54 resulted in a redesignation to B-54 with the planned reconnaissance variant being the RB-54. The jump in power output from the use of the Wasp Major VDT resulted in a redesign of the wings that resulted in a wingspan that was over 20 feet longer than that of the B-50 with a chord increase as well- an additional six feet of chord at the wing root and an additional four feet of chord at the wing tip. This provided additional fuel capacity along with external fuel tanks which were three times the capacity of the external tanks used on the B-50A on the outboard wings. The wingspan increase was so much that outrigger gears were needed under the outermost engine nacelles. Wind tunnel testing had shown that the new wing and powerful engine output also required a longer fuselage and the B/RB-54's fuselage was stretched 10 feet. Instead of the plexiglass domes used by the gunners on the B-29/B-50, low drag hemispheric sights were used. These used a fish eye hemispheric optical element that the gunner sighted through. Glenn's Computer Museum has some great pictures of the R/RB-54 hemispheric gunsight. The tail gunner also had a hemispheric gunsight but also had a radar to direct the four-gun turret as well which was mounted in fairing above the gun turret but below the hemispheric gunsight. Fairings were also present on the nose and under the forward fuselage for bombing and navigation radars. 

As a comparison, the B-29 weighed 120,000 lbs fully loaded and the B/RB-54 would weighed in at 207,000 lbs at takeoff. The Wright R-3350 engines of the B-29 developed 2,200 horsepower and the bomber had a range of approximately 3,250 miles. The B/RB-54 would have been able to push 8,000 miles of range. The mockups were completed in 1948 and the contract was signed for 43 bombers as an initial production lot. While the Secretary of the Air Force Stuart Symington and the USAF Chief of Staff General Hoyt Vandenberg were supportive of the B/RB-54 project, General Curtis LeMay, the head of the Strategic Air Command, felt that the B/RB-54 was inferior to the Convair B-36 Peacemaker particularly the B-36D that added four J47 jet engines under the outer wings. Pending the arrival of the B-52 Stratofortress, LeMay felt deterrence was better served by the B-36 which could fly faster, farther, higher, and carry a significantly larger bomb load. In the postwar atmosphere of austerity, more B-36s couldn't be accommodated in the Air Force budget and Secretary Symington offered LeMay more B-50s instead of increased numbers of B-36s. This was even more unsatisfactory to the outspoken SAC commander who then argued that if he couldn't get more B-36s, then the funding set aside for the B/RB-54 should be shifted over to get more of the Boeing B-47 Stratojet which made its first flight in December 1947. This was agreeable to all involved, even for Boeing as it meant more funding for the Stratojet program. The B/RB-54 project was cancelled with the prototype approximately 75% complete (it was converted from a B-50A) at Boeing's Seattle facilities. In addition, the addition of the outrigger gears wasn't popular with SAC as many of its bases would need widened taxiways and runways to accommodate the B/RB-54. 

The B-29 lineage would live on, though, in the C/KC-97 Stratofreighter (the last examples being retired in 1978) and in the commercial Boeing 377 Stratocruiser. But neither would have matched the leap in performance of the B/RB-54, the "ultimate" Superfortress.

The Retromechanix page has a series of superb photos via the National Archives that show the B/RB-54A mockup in detail as well as some schematic drawings. It's well worth the time to browse them!

Source: Boeing B-29 Superfortress (Crowood Aviation Series) by Steve Pace. The Crowood Press Ltd, 2003, p166-168. Boeing B-50 (Air Force Legends Number 215 by Geoffrey Hays. Ginter Books, 2012, pp 118-121.

19 September 2015

The XB-15: Getting Boeing Back On Its Feet

Clairmont Egtvedt led Boeing during its most precarious times
(Boeing Historical Archives)
The Boeing Company of the mid-1930s was existing by only a razor-thin margin and at any moment in those times, could have shut down for good with the Boeing name a mere footnote in aviation history. Why one of the dominant aviation companies of today nearly ceased to exist eighty years ago we have to move the clock back to 1929 when President Herbert Hoover appointed Walter Fogler Brown to be the Postmaster General. Within a year, Brown had lobbied Congress for more authority to improve the air mail system which he felt was inefficient and piecemeal in the organization of the existing airline networks that carried the mail. The Air Mail Act of 1930 (also known as the McNary-Watres Act after its Senate sponsors) gave Brown the authority to rationalize the US air mail system, which in effect, led to the rationalization of the US airline system of the day. The details of that controversial move will of course will be the topic of a future blog article here at Tails Through Time- but the key event here was the so-called "Spoils Conference" of 1930 where Brown consolidated the existing air mail routes which by extent led to the consolidation of the US airline system to just three airlines- United, TWA, and American- essentially forcing out of business the other airlines. One of the effects of this move was that Bill Boeing teamed up with Frederick Rentschler of Pratt & Whitney to form a large business conglomerate with diverse interests in aviation called United Aircraft and Transport Corporation. United Aircraft was the holding company for both Boeing Aircraft and Pratt & Whitney and also held ownership of Hamilton Standard, the propeller manufacturer, as well as the aircraft companies of Chance Vought, Sikorsky, and Stearman along with United Air Lines. In late 1933, Senate investigations opened on the 1930 Spoils Conference which led to the Air Mail Scandal of 1934 which led to the Roosevelt Administration canceling all the air mail contracts and handing the air mail delivery to the US Army Air Corps with disastrous results. With no choice but to return air mail service to the airlines, the government did so with punitive conditions that large consolidated aviation firms with airline interests had to be broken up in order to win back air mail contracts. United Aircraft was broken up back into its constituent companies and Bill Boeing resigned from aviation altogether. 

Replacing Bill Boeing was his general manager, Clairmont "Claire" Egtvedt, who had risen up the ranks at Boeing after starting out as a draftsman in 1917 fresh out of college. Of all the pieces of the now-broken up United Aircraft, Egtvedt had to take charge of the smallest and weakest piece- Boeing Aircraft itself which included its Stearman subsidiary in Wichita, Kansas. The first year of Boeing's new independent existence found it operating at a loss of over $200,000, a crushing loss in those days. Egtvedt wanted to get Boeing back into business by building a twin-engined bomber and twin-engined transport, but there was just barely enough money in the company's accounts to make payroll. By the late summer of 1934, Boeing's workforce had fallen from 2,275 a year earlier to only 600. The remaining employees as a testament to their faith in Boeing, offered up a plan to Egtvedt where half the group would work two weeks and then the other half of the group would then work the next two weeks and keep alternating so that only half the employees needed to be paid but the core experience of Boeing could be kept intact. Egtvedt naturally approved of the plan and true to the loyalty of the Boeing employees, some of those where not assigned to work in a particular two week block came to work anyway to help out without asking for payment. 

What Boeing products were available needed to be sold overseas to earn income for the company, so Egtvedt hired a young engineer, Wellwood Beall, who had been an instructor at Boeing's own school of aeronautics. Beall was an enthusiastic and gregarious individual who Egtvedt tasked with selling the Boeing P-26 Peashooter to the Chinese, who ended up ordering eleven aircraft in 1935. But it wasn't enough, and even the in-house company newspaper shut down publication to save money. Ever looking for opportunities to turn Boeing's fortunes around, Egtvedt had always thought the Boeing 247 airliner was too small, which as it turned out, became its biggest liability to the roomier and bigger Douglas DC-3 which proved to be an immense success. Several years earlier Egtvedt actually watched flight operations with Boeing fighters aboard the first US aircraft carrier, the USS Langley. A Navy rear admiral who was hosting the Boeing delegation remarked that battleships made more sense than bombers (this was in the wake of General Billy Mitchell's demonstration where he sank captured German warships with bombers) for US defense because a battleship could defend itself. When pressed further by Egtvedt, the admiral responded that the only practical bomber would be one that would be able to defend itself like a "flying dreadnaught". The remark must have stuck with Egtvedt that bigger was the way to go, but the only large aircraft of the day in the United States was the Barling bomber of 1920 that had a 120-foot wingspan, six engines and needed a tailwind to break 90 mph and had a range of only 300 miles on account of its heavy weight. Large aircraft simply had a lousy track record in those days. But that didn't stop Egtvedt from thinking about the large aircraft problem. Bill Boeing himself once said: 

"I've tried to make the men around me feel as I do, that we are embarked as pioneers upon a new science and industry in which our problems are so new and unusual that it behooves no one to dismiss any novel idea with the statement that 'It can't be done'. Our job is to keep everlastingly at research and experiment, to adapt our laboratory results and those of other laboratories to production as soon as practicable, to let no new improvement in flying and flying equipment pass us by."

The XB-15
(Boeing Historical Archives)
Boeing wasn't just thinking about bigger aircraft. There were also some officers with the US Army Air Corps that saw Billy Mitchell's 1921 demonstrations as prescient and the key to making the United States an aviation power. At the lowest point of Boeing's fortunes in the spring of 1934, Egtvedt got a phone call from Brigadier General Conger Pratt who was head of the Air Corps Materiel Division at Wright Field in Dayton, Ohio (predecessor to today's USAF Systems Command). Pratt wanted Egtvedt's presence at a secret conference in Dayton to which he also invited the heads of several other aircraft companies. Within the Air Corps, many of Mitchell's subordinates were imbuing the USAAC with ideas of long range bombers which received high level support with the command staff in Washington. At the meeting on 14 May 1934, General Pratt informed the aircraft company leaders that the Army wanted proposals for a long range bomber that could carry at least 2,000 lbs of bombs at least 3,000 miles and weigh no more than 32 tons. Nothing like it had been done before and the invited guests were quite startled. 

Egtvedt immediately put Boeing engineers to work on a 150-foot wingspan bomber called "Project A". The speed at which Boeing got to work on Project A resulted in a design contract from the Army. A large hangar at Boeing Field was set aside with a partitioned area only cleared personnel were allowed along with Army representatives from Wright Field. Excitement built quickly at Boeing with word of a mammoth bomber in the works. Despite the Army contract, Boeing's financial state was still quite precarious, but Egtvedt pressed on- Boeing, in his mind, had to learn how to build large aircraft if it was going to survive and Project A would be the company's school house, even if the company ran in the red- which it did. 

With work proceeding on what would become the XB-15, a second proposal was issued by Air Corps Materiel Division at Wright Field. While the first project was to be a technology demonstrator of a large bomber aircraft, the second proposal that was issued on 8 August 1934 just months later called for a production bomber with a 2,000 lb bomb load, a top speed of 250 mph, a range of 2,200 miles and a crew of around six. Companies were asked for designs and bids for an initial production run of just over 200 aircraft. You can imagine Claire Egtvedt's excitement with this second proposal- he had been thinking about larger aircraft and Boeing was learning all about designing and building larger aircraft with the XB-15 demonstrator. He had been thinking about a flying dreadnaught that a Navy admiral referred to years earlier and now the Army was asking for that very aircraft. Egtvedt wanted the Boeing proposal for the production bomber to be a four engine aircraft, but in those days, four engine aircraft were rare and seen as risky from a technological standpoint. He even flew to Wright Field to get further clarification on the production bomber specifications to be sure a four-engined design was acceptable. 

Egtvedt didn't just want to submit a proposal- he wanted to something daring. He wanted to proceed with a prototype of Boeing's proposal and fly it to Wright Field to demonstrate its performance. This was an immense gamble- Boeing was already operating in the red, it was busy working on the XB-15 project and now Egtvedt wanted to build and fly a prototype of Boeing's submission within one year. Egtvedt turned to his friend for guidance- Boeing's company lawyer and future CEO, William M. Allen. Allen came from the University of Montana but had a Harvard law degree- he first worked with Boeing in setting up Boeing Air Transport in 1926 (the predecessor to United Air Lines). Allen was an unusual sort for the Boeing team- he wasn't a pilot and he wasn't an engineer. But he had a remarkable clarity of thought that many at Boeing came to rely on to help with tough decisions and he asked Egtvedt bluntly "Do you think you can build a successful four-engined airplane in a year?" Egtvedt's response evoked the spirit of Bill Boeing: "Yes I know I can." So with Bill Allen's support, on 26 September 1934, Boeing's board of directors authorized Egtvedt to borrow money to the limit to begin work on the Model 299. 

Model 299 prototype
(USAF Museum)
In less than three months the production drawings for the Model 299 were in the hands of assembly shop who began building the prototype, all while work continued on the XB-15 program. As assembly of the Model 299 prototype began, the company ran out of money and the board, putting its faith in Claire Egtvedt, arranged to borrow more money. While it was clear that the XB-15 would never be a production aircraft, what had been learned from the design effort paid dividends for Boeing in the speed at which the design and fabrication of the Model 299 proceeded. Final assembly began in June 1935 and soon workers disregarded their shifts in an all-out effort to finish the Model 299 prototype. At sunrise on a Sunday, 28 July 1935, the Model 299 prototype was rolled out at Boeing Field for its successful maiden flight. Keep in mind the go-ahead to launch the Model 299 program was on 26 September 1934! After a stunning first flight, the Model 299 was then flown to Wright Field on 20 August 1935, taking only nine hours to cover over 2,000 miles with an average speed of 252 mph. Boeing's other competitors also built flying prototypes of their submissions but they paled in comparison to the Model 299. Martin entered the YB-12 which was just a re-engined version of the B-10 twin-engined bomber and Douglas entered the B-18 Bolo which was based on the DC-2 airliner. 

Then tragedy struck. During a flight test out of Wright Field in October, the control locks were left in place and the Model 299 prototype stalled at takeoff and crashed with the loss the pilot and varying degrees of injuries to the rest of the crew. Under the rules of the competition laid down by the Army, the Model 299 had to be eliminated from competition as it was unable to complete its flight tests. It was a somber Christmas 1935 when Douglas won the contract with the B-18 Bolo. But there was a silver lining in the loss of the Model 299 prototype- the flight test program won the Model 299 many advocates within the US Army Air Corps who saw the Boeing design as the future of long range bombers. A service order was placed for thirteen aircraft and a fourteenth aircraft that would be a structural test article. The aircraft's designation would be a name that would echo in the annals in the history of aviation- B-17. When the Seattle Times reporter Richard Williams dubbed the Model 299 a "flying fortress" on account of its six gun turrets, Boeing astutely saw the value of the name and the B-17 became the Flying Fortress. 

Work did continue on the XB-15, though- it made its first flight on 15 October 1937. It was 26 feet longer than the B-17 with a 36-foot greater wingspan and at the time of its rollout, it was the largest bomber ever built. The aircraft was christened "Old Grandpappy" in recognition of the role its design played in the B-17 Flying Fortress. The service history of the XB-15 will also be the subject of a future article here at Tails Through Time, so stay tuned! 

Sources: Boeing: The First Century by Eugene E. Bauer. TABA Publishing, 2000, pp 59-69. Legend & Legacy: The Story of Boeing and Its People by Robert J. Serling. St. Martin's Press, 1992, pp 27-35.

14 September 2015

Operation Drugstore: The 1982 Air Battles Over the Bekaa Valley









09 September 2015

Fall from Triumph: The Sad Story of Tryggve Gran of Norway

1944 Norwegian stamp commemorating Gran's flight
(from Wikipedia)






Tryggve Gran in 1923
("Tryggve Gran 1923" by Anders Beer Wilse)



04 September 2015

The Aircraft Operated from Submarines in World War I

The Friedrichshafen FF29 on the bow of U-12
(from the War Relics Forum)



Sopwith Schneider floatplanes on the aft deck of the sub E22
(from @RNSubMuseum's Twitter stream)


The Brandenburg W20 flying boat
(from Their Flying Machines)

The LFG Roland V19 "Putbus"
(from Google Snipview)
