Flying Boats

by Jim "Twitch" Tittle

Article Type: Military History
Article Date: January 02, 2002


Today, big flying boats are an extinct military species. In WWII they were the only way to deliver supplies to certain locales, perform rescue at sea, and maintain a reconnaissance influence. Later they were fitted with bombs and depth charges to combat enemy vessels as needed. Some smaller flying boats are used by most country's naval forces for rescue and utility, though helicopters have taken over much of that function.

A Big One: Bv 238

There were not a lot of quality airfields in the late 1930s. Remote areas certainly had none. Nations with forward airfields usually constructed them hastily and were usually not long enough to handle larger aircraft. Being heavy and slow these planes would have required excessively long take off runs if they were land planes. This changed as the war progressed but initially big flying boats could go and land anywhere. This was a huge asset.

While many were slow and not heavily armed, a favorite tactic of such planes was to use the clouds for cover if they were discovered or hug the wave tops to make an enemy's firing pass difficult. Rough water take-offs and landings were an acquired skill and a wave struck wrong could split the hull.

Japan

Being an island nation with an island empire, Japan developed flying boats in the early 1930s. While Japan never developed four-engine land-based bombers they did focus on big flying boats. The Kawanishi Type 97 H6K1 to K5 models ranged far and wide beginning in 1936. Quick, long-range transport could be made to far flung islands in the vast Pacific.

In Allied fashion code-naming bombers with female names and fighters with male names, the Type 97 was dubbed Mavis. This was a big plane with a 131' wing that was raised above the fuselage. On it were four 1,300 hp Mitsubishi Kinsei 53 14-cylinder air-cooled radials that could take the nine-man crew 4,210 miles making for twenty-six hour mission endurance if required. It was slow with a top speed of only 239 mph at 19,685 ft. and it took 13.5 minutes to reach a 16,400 ft. altitude. It was rather heavy at 38,580 lbs. normal and 50,706 lbs. maximum loaded weights. The ceiling was 31,365 feet.

The Mavis could launch two 1,764 lb. torpedoes or carry 4,400 lbs. of assorted sized bombs. She had a 20mm tail stinger and four 7.7mm machine guns in various beam blisters, the nose and a dorsal turret.

With modest armament and no armor or self-sealing tanks, Type 97s were very vulnerable to fighter attacks and they were gradually withdrawn from daylight operations as the war progressed. After extensive use, by 1943 production was ended with 217 machines and its successor began replacing it.

You Go Girls! Mavis & Emily

The Kawanishi Type 2 H8K1 to K4 was up to the task. Emily was this flying boat's Allied designation. It was designed as the Type 97's replacement in 1938. The H8Ks were large with 124' wingspans. Over all it was a beefier design with self-sealing tanks that could provide an awesome range of 4,447 miles maximum. Loaded and maximum loaded weights were 54,013 lbs. and 71,650 lbs. respectively. The four 1,850 hp Mitsubishi Kasei 22 14-cylinder air-cooled radials could move it along at 290 mph at 16,400 feet. Ceiling was lower than the Mavis at 28,740 feet. Climb was good for so large a plane gaining 16,400 feet in just ten minutes. 167 of these high quality planes were built.

The crew of ten had good defense. Three 20mm cannons in the nose, tail and a dorsal turret were complimented by four 7.7mm MGs in lateral positions. Two 1,764 lb. torpedoes or 4,400 lbs. of bombs could be included offensively. The ample armament along with armor plate and protected gas tanks made this monster hard to shoot down by a fighter.

It is interesting to note that three debuting H8K1s departed the Marshall Islands in March 1942 intent on bombing Oahu 2,000 miles distant. They rendezvoused with a refueling submarine 650 miles from Hawaii and continued on but found a heavy cloud layer covering the island and aborted any attack.

Germany

Used to small extent was the three-engine, twin boom tail Blohm & Voss Bv 138. The Dornier Do 24 saw more service. Mounting three 1,000 hp BMW/Bramo Fafnir 323R-2 18-cylinder radial engines on the high wing it could manage 211 mph at 5,560 feet. The aft section arced up gracefully where a twin-tail horizontal stabilizer was mounted. Loaded at 40,565 lbs. the 88-foot wing could lift the plane to 19,360 feet. Climb to 6,560 feet took a laborious 14.5 minutes but it had a good range of 2,950 miles.

A 7.9mm MG 15 was mounted in the bow and tail plus a 20mm MG 151 was carried in a dorsal turret. 1,320 lbs. of bombs could be delivered. It served in Northern European waters and even in the Far East. Many were put into service by several countries after the war. About eighty-seven were completed.

Do24 & Wiking

Germany had gigantic six-engine flying boats in the prototype stage flying but never put emphasis on final development for many reasons, but mainly resource allocation.

The Blohm & Voss Bv 238 prototype was a huge plane envisioning a crew of ten. Its 197' wingspan had six 1,750 hp DB 603V engines for motive power to get the massive flying boat airborne. Speed was on the order of 264 mph at 19,685 ft. and 216 at sea level. Its maximum weight loaded was 176,370 lbs. but normal weight was 154,324 lbs. Range was not that long at 2,395 miles though the projected Bv 250's range could have been a staggering 8,700 miles in its long-range configuration.

11,000 lbs. of ordnance would have been droppable from wing-mounted bomb bays (yes, wing-mounted!) of the Bv 238 plus externally four tons more of an assortment of bombs, torpedoes and even Henschel missiles could be attached. Defensively 13mm and 20mms were suggested at several stations with vast amounts of ammo for each weapon—up to 7,200 rounds for the nose-mount 13mm!

The one Bv 238V1 prototype flying boat, was destroyed by Ben Drew's P-51 in the spring of 1944 as it rested on Lake Schaal.

Twelve prototypes and production examples of the BV 222 Wiking recon/transport flying boat were built. This plane seemed more realistic in its specifications and looked to be a scaled-up Short Sunderland from many angles. The production "C" model had a wing that spanned 150 feet and carried six 1,000 Junker Jumo 207C 12-cylinder diesel engines. Diesels were used on other German aircraft and the Russians used them on their few heavy bombers. With a normal weight of 100,503 lbs. its crew of 11-14 men could cruise to a maximum range of 3,790 miles. This translated to 28-hour mission endurance. The ship had a top speed of 205 mph at sea level and 242 mph at 16,400 feet but climb rate was a slow 413 fpm.

The V1 prototype actually transported supplies for the Afrika Korps in 1941 and it had a capacity for ninety-two combat troops with a range of 5,655 miles. The V4 in fact destroyed a Lancaster over the Atlantic in October of 1943 with it substantial defensive armament that consisted of a 13mm in the bow, a 20mm in a forward dorsal turret, four 13mm in lateral positions and amazingly, two 20mm turrets in the wing inboard of the number one and number six engines. No provision for bombs was made.

With the turn in the war, full production was never realized. Both Great Britain and the U.S. procured Wiking examples after the war. Two had been readied for escape use, anchored on Lake Havel near Berlin, in the waning days of April 1945. Obviously Hitler never used the big plane.

Great Britain

The real flying boat success story of WWII was that of the Short Sunderland that entered RAF service in 1939. Before the influx of B-24s to the UK for anti-submarine patrol, it was progressively developed and by 1943 Costal Command had many U-boat kills to their credit. Throughout the war 721 machines of all models were built. Its Luftwaffe nickname was "Stachelschwein" or Porcupine due to its substantial gun armament. The Sunderland V had two .303s fired from the bow turret with two more in a fixed position. Four .303s were housed in the tail turret and two .50s were operated from lateral mounts.

The Sunderland

The crew of ten could make 213 mph at 5,000 feet thanks to four 1,200 hp Pratt & Whittney R-1830-90B 14-cylinder engines. Climb was not bad for a 60,000 lb. bird with 840 fpm. Though the ceiling was 17,900 feet most Sunderlands spent their time nearer to sea level dispensing their 4,960 lbs. of bombs and depth charges on German shipping. With 1,668 lbs. of ordnance they could travel 2,690 miles cruising at 133 mph. Wingspan measured 113'.

With good performance and substantial numbers built, the Sunderlands defined what a flying boat was all about.

United States

The twin-engine Consolidated PBY Catalina was not well armed nor could carry the bomb load of the Sunderland but proved its worth nonetheless. With high production rate (3,290 were built) it was seen in every locale of the war. In the Pacific its worth was realized as long-range reconnaissance craft and in the Atlantic it patrolled with depth charges seeking U-boat victims. A British Catalina spotted the elusive Bismark's location and course before she was engaged in her final battle.

The two P & W R-1830-92s of 1,200 hp each were nearly the same as those used on Sunderlands giving a top speed of only 179 mph at 7,000 feet but it could cruise at 117 mph for 2,545 miles though not fully loaded with its maximum load of 6,000 lbs of ordnance. Its ceiling was but 14,700 feet and it took over nineteen minutes to attain 10,000 feet. A normal loaded weight was 32,415 lbs.

A ventral .30 caliber, two more .30s in the nose and a .50 in each side blister defended the lumbering ship. Many a downed airman was happy to see the ungainly bird arrive to rescue them. Cats were produced in Canada and in the Soviet Union where an unknown number were manufactured.

Catalina & PBM

Consolidated also built 210 of the little-used four-engine PB2Y Coronados and Martin completed 1,289 twin-engine PBMs. The eight-man PBM was a step above the PBY in many areas such as performance. The -5 model had two 1,900 hp Wright Cyclone R-2600-22 14-cylinder air-cooled radials made for a top speed of 211 mph at 16.000 feet and gave it a ceiling of 19,800 feet. The 51,330 lb. plane enjoyed a range of 2,240 miles but had a stronger structure overall beneath its 118' wings.

It could haul 8,000 lbs. of bombs and defended itself with three .50 caliber turrets with twin guns in the nose, tail and dorsal positions. A further .50 caliber was mounted on each side in lateral beam locations.

Soviet Union

Beriev first introduced the MBR-2 flying boat in the early 1930s. The MBR-6 was a completely new aircraft that came on the scene and was built in substantial numbers from 1939-44. It was a sleek five-seat design with two 1,100 hp M-63 9-cylinder radials or M-105A V-12s respectively in the -MDR-6A. The 6A could fly at 267 mph at 16,400 feet and climb to a whopping 39,370 feet with a range of around 750 miles. Loaded it weighed 16,534 lbs.

It had two turrets—nose and dorsal—each with a 7.62mm ShKAS machine gun. Ordnance included up to 1,100 lbs. of bombs, torpedoes or depth charges.

MBR-6 & BE-10

It is worthy to note that the Russians were the last nation to produce flying boats at least into the 1960's. Beriev built the BE-10 for the Soviet Navy with squadrons formed in 1960-61. At the same time the BE-12 turboprop flying boat was emerging into service. The BE-10 had two 14,330 lb. thrust Type AL-7PB turojets close in to the fuselage beneath a 73' swept wing with tip floats. The jet could hit a seaplane record of 565 mph at 5,000 feet with a 90,000 lb. loaded weight and topped out at 48,000 feet. Range was 1,300 miles.

Two 23mm cannons were housed in the nose with its search radar and two more 23mms resided in a tail station. A medium bomb load of about 12,000 lbs. was housed internally and delivered via a rotary bomb bay.

France and Italy had flying boats that were in service in the pre and early war stages also, but production quantities were small.

Sources

• Green, William
  Flying Boats Vol. 5
  Doubleday & Co., NT, 1962
  
  
• Munson, Kenneth
  Bombers
  The MacMillian Co., NY, 1966
  
  
• Rolfe, Douglas
  Airplanes of the World
  Simon & Shuster, NY, 1954
  
  
• Taylor, John W.R. & Swanborough, Gordon
  Military Aircraft of the World
  Charles Scribner's Sons, NY, 1979

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