Messerschmitt Bf.108, part five

Among the many foreign users of the Messerschmitt Bf.108 were both the United States of America and the Kingdom of Yugoslavia.

• United States of America: The aircraft depicted below belonged to the U.S. Military Attaché for Air in Berlin. It was bought in the spring 1939 and was officially designated as Messerschmitt XC-44. In November 1941 it was condemned and shortly after, in December 1941 after the Germany declared war on the USA, the aircraft was repossessed by the German authorities.
• Kingdom of Yugoslavia: Yugoslavia closed a deal with Germany to buy some Messerschmitt Bf.109E fighters. Given the technical complexity of those new fighters, Yugoslav pilots had to be trained in simpler aircraft, so the most logical choice was the Bf.108. At least nine of them were purchased by the Royal Yugoslav Army Air Force. Two of them were assigned to the 710th Liaison Squadron, based in Lješnica and the other three were assigned to the Air Training School, based in Mostar.
  Some other also served in the liaison role, with the 702nd Liaison Squadron based in Zemun, with the 703rd Liaison Squadron, based in Nova Topola, with the 704th Liaison Squadron, based in Stubol and the 705th Liaison Squadron, based in Ljubic. All of them were either destroyed in 1941 when Axis powers invaded or captured (see our previous post for one Italian captured Bf.108 for another example).

Sources:

1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_108

2. https://www.valka.cz/Nord-1001-Pingouin-I-t85450

3. https://en.wikipedia.org/wiki/Nord_Pingouin

4. http://www.warbirdalley.com/bf108.htm

5. Wydawnictwo Militaria 149 - Messerschmitt Bf-108 Taifun

6. https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=347

7. https://www.wikizeroo.org/index.php?q=aHR0cHM6Ly9lbi53aWtpcGVkaWEub3JnL3dpa2kvWXVnb3NsYXZfb3JkZXJfb2ZfYmF0dGxlX3ByaW9yX3RvX3RoZV9pbnZhc2lvbl9vZl9ZdWdvc2xhdmlh

Messerschmitt Bf.108, part four

The Messerschmitt Bf.108 was a sport and touring aircraft that was widely used all around the world. The countries covered in this post are:

• France: The French Armée de l'Air (French Air Force) operated a number of captured Bf.108s during the late stages of the World War 2 just before the liberation. After the War it was built by SNCAN (commonly known as 'Nord') and was used also by both the Armée de l'Air and the Aéronavale (French Naval Aviation). 
• Italy: The Italian forces stationed in Albania captured at least one ex-Yugoslavian Bf.108 in 1941 which was assigned to the Reparto Volo Commando (Flight Command Department) of the Aeronautica Albania (Albania Air Force Command). Later it was assigned to the Gruppo Autonomo di Volo (Autonomous Flight Squadron) of the 3ª Squadra Aerea based in Rome where it served at least until 31st July 1943. It's fate is unknown.
• Switzerland: In 1936 the Swiss Air Force bought some Bf.108s which were used in communications flights until the late 1940s. 
• Nationalist Spain: During the Spanish Civil War the Condor Legion employed some Bf.108 in liaison and VIP transport duties. It seems that just four Bf.108 operated with the Condor Legion during the war. In 1939, after the war ended, they were inherited by the newly re-funded Ejercito del Aire (Air Force) and got another additional three machines.

Sources:

1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_108

2. https://www.valka.cz/Nord-1001-Pingouin-I-t85450

3. https://en.wikipedia.org/wiki/Nord_Pingouin

4. http://www.warbirdalley.com/bf108.htm

5. Wydawnictwo Militaria 149 - Messerschmitt Bf-108 Taifun

6. https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=347

Messerschmitt Bf.108, part three

The Messerschmitt Bf.108 was a German single-engine sports and touring aircraft that was used by many countries all around the globe. Among many users, it was also used by the next ones:

• Brazil: At least one was used by Viaçao Aerea Rio-Grandese (VARIG) airline during the 1930s and was most probably used as a VIP transport.
• Chile: One Bf.108 was purchased directly to Messerschmitt by the Chilean senator Carlos del Campo in the mid-to-late 1930s. After a brief period of using it as his personal transport, he sold it to LAN (Linea Aérea Nacional - National Airline) who operated the aircraft as a VIP transport and was painted with the colours depicted below. With the outbreak of World War 2, as spare parts became a problem, it was sold again to another unknown customer who kept it left to rot in a barn. In the mid 1960s some Chilean air enthusiasts tried to buy the plane but the owner sold it to some North American customer. It was then when the trace of this Bf.108 vanished. According to some people it was sent to the USA where it was repainted and restored to flying condition, while some other claim that it was repainted and shown in a museum. However, the real fate of the aircraft is still a mystery.
• Czechoslovakia: The Czechoslovak Air Force operated some ex-German exemplars after the War. They were renamed as K-70 and served with the Transport Squadron based at Prague's Kbely airbase.
• Japan: The Imperial Japanese Army Air Service bought some few Bf.108 for testing purposes. They were assigned to the Army Aviation Experimental Centre in Japan, where they were tested during the 1930s. After testing they decided to not order them and they were passed on to Manchukuo, their main puppet state in Asia.
• Manchukuo: From 1936 until 1940 the Manchukuo National Airways (MKKK) (which in spite of its name was a paramilitary organisation) used some Bf.108 ceded from Japan for light transport and reconnaissance duties. 
• Norway: It seems that some few ex-German machines were used by the Royal Norwegian Air Force during the post-war period. As we couldn't find graphical evidence, the colours should be considered speculative.
• Poland: The Polish Central Staff for the Aviation League operated some ex-German Bf.108 during the post-war period. It was also used by the Polish Internal Security Corps which was the Polish counterpart of the Soviet NKVD.

Sources:

1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_108

2. http://www.warbirdalley.com/bf108.htm

3. Wydawnictwo Militaria 149 - Messerschmitt Bf-108 Taifun

4. https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=347

Messerschmitt Bf.108, part two

The Messerschmitt Bf.108 was widely used across the world. Some of the users were:

• Nationalist China: Apparently Nationalist China had at least one Bf.108B-2 in the ranks of their Air Force at the year 1939. Further information is required and the drawing should be considered as speculative.
• United Kingdom: The Royal Air Force (RAF) interned four Bf.108s at the outbreak of the war and put them into service under the designation of "Messerschmitt Adlon". They became the fastest communication aircraft of the RAF but they were often mistaken for Bf.109s, so they weren't employed very much. After the war, captured exemplars were used until at least 1948.
• Poland: The Polish Air Force used some captured Bf.108 after the war. They served until the very late 1940s.
• USSR: Before the war with Germany, the Soviet Air Force bought some few Bf.108s for evaluation. During the World War 2, many captured exemplars were put into service with the Soviet Air Force.
• United States: The U.S. Army Air Force (USAAF) evaluated some captured exemplars that were shipped to Freeman Army Airfield, in Indiana in September 1945. Apparently some of them served until the foundation of the U.S. Air Force (USAF) and flew for some time with the new American roundel in 1947.

Sources:

1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_108

2. http://www.warbirdalley.com/bf108.htm

3. Wydawnictwo Militaria 149 - Messerschmitt Bf-108 Taifun

4. https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=347

Messerschmitt Bf.108, part one

The Messerschmitt Bf.108 was a German single-engine sport and touring aircraft that was used for military liaison purposes during the World War 2. It was designed and developed by the Bayerische Flugzeugwerke in the 1930s and was exported to many countries:

• Austria: A single Bf.108 was ordered by the Austrian government on 22nd April 1937 and was delivered on 27th July. It was the only Bf.108 to serve with the Austrian Air Force and when Germany annexed Austria, it went back to serve with the Luftwaffe.
• Bulgaria: During the war Bulgaria bought a total of six Bf.108 in 1941. They were assigned to the 1st Courier Squadron but were used mainly for training purposes.
• Independent State of Croatia: The 15.(Kroat)/JG.52 squadron composed by Croatian pilots who fought in the Eastern Front, used some Bf.108 for liaison purposes outside combat zones. The one depicted below was used by four Croatian pilots on 19th September 1942 to fly to Uman, in the USSR, where they were based.
• Hungary: In 1937 the Royal Hungarian Air Force bought a total of seven Bf.108 which were used in a wide range of duties. From liaison, communications and even trainer. They served through the war on the Eastern Front and until the end of the war.
• Romania: The Royal Romanian Air Force had at least one Bf.108 at the beginning of the war. It was assigned to the 11th Courier Squadron which belonged to the 1st Air Corps. During 1943 and 1944 it was still in service.

Sources:

1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_108

2. http://www.warbirdalley.com/bf108.htm

3. Wydawnictwo Militaria 149 - Messerschmitt Bf-108 Taifun

Morane-Saulnier M.S.405

The Morane-Saulnier M.S.405 was developed to a requirement of a French fighter specification made by the French Air Ministry in July 1934. Even if it was a monoplane, it was in many other ways an outdated design. While Messerschmitt and Supermarine were using all-metal stressed skin constructions, with the metal surface of the fuselage provided structural strength, Morane-Saulnier built their aircraft using technology employed in previous biplanes. Structural strength was provided by a series of bulkheads connected by aluminium tubes, connected by wire-braced struts. The aircraft was skinned with Plymax , which was a composite material made of both plywood and aluminium. Thanks to that skin method the aircraft resembled the Hawker Hurricane, which was built using similar methods.
It was armed with just three guns, one 20mm Hispano-Suiza H.S.404 firing through the propeller's hub and two 7,5mm MAC 1934 machine guns in the wings, quite underarmed for 1939-1940.
The first prototype flew for the first time on 8th August 1935 and was powered by an Hispano-Suiza 12Ygrs engine which yielded 824 hp of power for take-off and 848 hp at 4000 m (13123 ft) high. It had a top speed of 480 km/h (298 mph) at 4000 m (13120 ft) high. It was a nice top speed for the year 1935, however, it would take up to three years of development. The second prototype didn't appear until January 1937 and was powered by an improved Hispano-Suiza 12Ycrs engine. This second prototype showed promising results and on 1st March 1937, the French placed a pre-production order of 16 models.
The first of the pre-production aircraft, flew for the first time on 3rd February 1938 at Centre d'Essais de Materiel Aérien (CEMA). The No.2 was sent to Reims for operational testing, after which, it was decided to change the engine again. This time a Hispano-Suiza 12Y-31 would be fitted and thus the first prototype for the M.S.406 was built, which was the one that entered mass-production. The first production order for the M.S.406 was placed in April 1938 and in May the M.S.405 flew with a new engine.
Three of the pre-production M.S.405 were used for experiments which resulted in new designations, like the No.3 which had fuel tanks placed in the wings to make space to fit a dummy parachutist. This experimental aircraft was called Morane-Saulnier M.S.407L.P.
The No.12 was fitted with a Hispano-Suiza 12Y-45 engine and became the prototype for the Morane-Saulnier M.S.411 (which was also a development of a previous M.S.410 variant). It flew for the first time on 24th January 1939 and it had a fixed-radiator (while the ones equipped with the 12Y-31 had a retractable one.
The No.13 had the same fixed radiator as the No.12 but included compartments in the wings for flares. It was given the designation of Morane-Saulnier M.S.408. This aircraft became the prototype for the Swiss-produced variant D-3800.
Apparently some M.S.405 were used during the Phony War and the German Invasion of France mixed with the more advanced M.S.406. However by that time there were so few of them that most of them were used testbeds for other types of engines as we've shown.

Sources:
1. http://www.historyofwar.org/articles/weapons_MS405.html
2. https://en.wikipedia.org/wiki/Morane-Saulnier_M.S.406#M.S.405
3. https://www.valka.cz/Morane-Saulnier-MS-405-C-1-t71689
4. Signal Squadron - Aircraft In action 180 - French Fighters of World War II in Action
5. Salamander Books - The Complete Book of Fighters
6. AJ Press - Monografie Lotnicze - Morane-Saulnier M.S.406

Messerschmitt Bf.109W

In 1941 the Reich's Aviation Ministry (RLM) asked Messerschmitt for the possibility of a floatplane fighter based on the Bf.109.
Messerschmitt chose the Bf.109F as the basis for this new project and, on the drawing designs, they added a pair of floaters taken straight from the Arado Ar.196.
Apparently nothing came out from this idea and it was therefore abandoned as the war progressed on. According to some sources, the project was also drawn around the Bf.109T which was a sub-variant of the Bf.109E. If it went ahead, it would've been developed by Blohm & Voss, which apparently were going to add a third central floater and replace the lateral ones with two smaller floaters, kinda like the floater version of the Mitsubishi A6M and was going to have also a modified tail and larger wings.
Anyway, the initial Messerschmitt's version was also going to be able to operate from ships but, as we've said before, its development was halted as it was envisioned that a floater equipped Bf.109 would've been very heavy and cumbersome and would've been an easy prey for conventional fighters. Both Japanese and British had the same idea of fitting floats to their main fighters.
As this project is shady and the information available is short, the whole project should be taken with a grain of salt.

Sources:
1. http://me109.airwar1946.nl/family/109W.htm
2. https://forum.axishistory.com/viewtopic.php?t=64377
3. http://home.catv.ne.jp/kk/galland/bf109w/bf109w1.html (translated)

Messerschmitt Bf.109X

The Messerschmitt Bf.109X was yet another variant of the Bf.109 with two sub-variants.
Its inception can be traced back to 1937 when, after the demonstration meeting in Zurich, Ernst Udet was receptive to the idea of creating an export version of the Bf.109 but powered with a different engine than the DB.601. The Pratt & Whitney R-1830 radial engine (AKA Pratt & Whitney Twin Wasp) was chosen which could yield 1200 hp of theoretical power. Messerschmitt received a contract from RLM (Reich's Aviation Ministry) on 13th June 1938 to install the R-1830 on the Bf.109V-21. Apparently, it flew for the first time on 17th August 1939 at Augsburg. However, it's not known the exact date and most probably it had already flown before. In September 1940, as the first prototype wasn't very useful in combat, it was part of the Deutsche Versuchsanstalt für Luftfahrt - DVL (German Flight Research Institute) located at Brauschweig-Völkenrode. It's fate is unknown.
A further development was made as the BMW 801 radial engine became available. A single Bf.109F was fitted with the BMW 801, which became the prototype for the Bf.109X. The fuselage had a wider cross-section and it was fitted with a new canopy. Wing tips were like the ones found on the Bf.109E. It flew for the first time on 2nd September 1940 by Flugkapitän Fritz Wendel. Tests continued , in spite of the usual troubles with the BMW 801A engine, until early 1942, when development was stopped.
Testings showed that the engine behaved better when diving than the standard Daimler-Benz engine, but the BMW had some serious problems with the oiling system and didn't offer, overall, much more improvement when compared to the Bf.109F. After the Focke-Wulf Fw.190 entered service with the BMW 801 A engine the project Bf.109X was definitely cancelled and the prototype was destroyed in early 1942.

Sources:
1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_109_variants#Bf_109X
2. http://www.germanaircraftwwii.org/2015/02/messerschmitt-bf-109x.html
3. AJ Press - Monografie Lotnicze 44 - Messerschmitt Me.109 Cz.3 (Translated)

Messerschmitt Me.509

Although the Messerschmitt Me.509 was related to the Me.309, not a lot of information survived the war. It was to be an all-metal fighter with a new fuselage featuring a pressurized cockpit which was placed well forward close to the nose, mimicking the cockpit configuration previously seen in the Bell P-39 Airacobra.
It was going to be powered by a single Daimler Benz 605B 12 cylinder engine with a expected power of 1455hp, that was integrated in the fuselage behind the cockpit. The engine was expected to drive a three-bladed reversible-pitch propeller by an extension shaft which passed beneath the cockpit.
The wing was tapered and had rounded wingtips which were mounted low on the fuselage. Some components from the Me.309 were going to be used, like the tricycle undercarriage and the vertical tail assembly, that was similar to the one used in the first prototype of the Me.309, the Me.309V1.
Armament wasn't decided upon, but most probably it was going to be armed with two 13 mm MG 131 machine guns and 20 mm MG 151/20 cannons, all of them placed in the wings, close to the fuselage. Apparently, just like the Me.309 the radiator was also extendable.
Even if there were real advantages with the new placement of the cockpit, as visibility was improved a lot, and the new engine weight placement, which was important since the Me.309's nose gear often collapsed due to the extra weight, the Me.509's design and development ended when  Messerschmitt put an end to the Me.309 program in mid-1943.
It's believed that, although no firm evidence exist, the Me.309/509's design information was licensed somehow to the Japanese (like it had happened with other designs like Bf.109, Heinkel He.100, Messerschmitt Me.163 or Me.410, among others) because some time later, in April 1945, the Japanese completed a somewhat similar design, the Yokosuka R2Y which had engine overheating problems.
We have decided to include some "what-if" variants like the tropicalized or the radar-equipped night fighter variants.

Sources:
1. http://www.luft46.com/mess/me509.html
2. https://en.wikipedia.org/wiki/Messerschmitt_Me_509
3. https://me109.info (translated)

Blohm & Voss Bv.155

In September 1943 the Reich's Air Ministry placed an order for five prototypes which was accepted by Blohm & Voss under the condition of having complete design freedom and not being bound by Messerschmitt's work to date. The redesign received the name of Bv.155 and received a new laminar flow, wing and tail unit, lading gear from the Junkers Ju.87 and many other parts of the plane. This first early redesign was known as the Bv.155A and it vaguely resembled the Bf.109K. It never went beyond the wind testing tunnel model as it was shown that overwing radiators (one of the features of the new redesign) created some serious problems at high angles of attack as the wing "blanked" them from the airflow and cooling would suffer so the model was abandoned with just one testing model having been built.
The revised B model went much further ahead and its first prototype, named V1 took off on 1st September 1944. When testing the V1 it was shown that the outboard radiators provided inadequate cooling, specially at high attack angles, just like with the wind tunnel model of the A variant so the intakes in the second prototype, V2, were enlarged and underslung beneath the wing instead of placing them over the wing. This changement, however, changed the aircraft's centre of gravity requiring the pressurized cockpit to be moved forward. The Blohm & Voss team took advantage of this problem to replace Messerschmitt's original cockpit with another aft-sliding all-round vision of their own and to cut down the rear fuselage decking. This required a larger rudder to be fitted as well as a new ventral enlarged radiator bath.
After all these changes, the Bv.155 V2 flew for the first time on 8th February 1945, but Blohm & Voss was still not satisfied with the design and, before the trials begun, they had proposed to switch the engine to the DB 603U having the larger mechanically driven supercharger of the DB 603E. The DB 603U promised a power of 1660 hp for taking off and 1430 hp at 14935 m (49000 ft) high. The ventral turbosupercharger was retained. The Technisches Amt accepted this new proposal and abandoned all work on the Bv.155B in favour of the revised design which was called Bv.155C.
The Bv.155V2 was damaged beyond repair due to a bad landing and was to be replaced by a third prototype, the Bv.155V3, which was fitted with the DB 603U intended for the Bv.155C, however, both the engine cowling and turbosupercharger were unchanged.
Various armament proposals were made for the Bv.155B. The first one had an engine-mounted 30mm Mk.108 cannon and two 20mm MG 151/20 cannons mounted on the engine cowling.
The second one had a 30 mm Mk.103 cannon mounted in the engine and two wing-mounted 20 mm MG 151 cannons. The third had three 30 mm Mk.108, one of them engine-mounted and the other two in the cowling and the fourth one was identical to the third one but with two Mk.108 mounted in the wing instead of the cowling.
Estimated maximum speed was 650 km/h (400 mph) at 12.000 m (52490 ft) with a service ceiling of 16950 m (55610 ft) high. According to some sources, both V1 and V2 were provided to the Royal Air Force after the war, which tested them until they were written off and V3 lies in storage at the US Air and Space's museum storage.
In parallel with the prototype development, Blohm & Voss had been working on additional changes under the name of Project 205. Project 205 (P.205) replaced the underwing radiators with an annular one around the front of the engine, a very common design feature found in many German designs of the time. With the wings free of clutter, they were considerably simpler and reduced in span. This also had the side effect of reducing the track , which turned to be a welcome change. The new design was going to be simpler, lighter and faster and it was planned to be the standard version of the aircraft. During October's re-evaluation, it was agreed that V1 to V3 were going to be completed to B standards, while a new series of five were going to be completed to the new standard as the Bv.155C. However, as with many other projects, the initial design (which we drawn) suffered many changes.
The Bv.155C was to be different from the Bv.155B. The wing mounted radiators were eliminated, and the main landing gear leg attachments were moved inboard to retract inwards. Cooling was provided by an anular frontal radiator just like the Focke-Wulf Ta.152. Large circular intakes were attached to the fuselage sides above the wing roots.

Sources:
1. https://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_155
2. Salamander Books - The Complete Book of Fighters
3. Monogram Close up 20 - Blohm & Voss BV155

Blohm & Voss BV.138, part three

The Blohm & Voss C-1 was the main production version of the aircraft with 228 machines having been made. The first one rolled out from the factory in March 1941 and production was continued at Blohm & Voss' factories from March 1941 until October 1943 with 161 aircraft being manufactured. The other sixty-seven of them were manufactured by Weser Flugzeugbau, in Nordenham, close to Hamburg.
It had a stronger structure and was powered by three 6-cylinder, liquid-cooled Junkers Jumo 205D opposed piston diesel engines that yielded a power of 880hp each. Both starboard and port engines drove three-bladed propellers and the central one drove a four-bladed one. It was ,engines wise, the same configuration as the previous B variant, except that the C one had wider propellers. This way the excessive vibration pressent in the A and B versions was eliminated. It was armed with two 20mm MG 151 cannons, one of them placed in the nose turret and another one placed in another turret in the rear fuselage plus a single 13mm MG 131 machine gun in an open position placed behind the central engine. The standard C-1 could carry three SC-50 bombs, the same amount as the B variant, while the version with underwing racks, the C-1/U1 could carry up to six SC-50 bombs or four 150kg (331lb) depth charges. Incredibly enough, some of them were able to be catapult-launched.
The Bv.138 in all its variants was used by long range reconnaissance units of the Luftwaffe, operating mainly off the coasts of France and Norway, from where they helped the U-Boat campaign and, while the initial A and B variants weren't very successful, but, as the C variant overcame previous variants' problems, it was the most produced and used one.
They also served in the Baltic Sea and the Black Sea.
The Bv.138MS was a mine-sweeper variant produced from modified B aircraft. All guns were removed and a circular dural hoop was installed surrounding the fuselage which was used to detonate magnetic mines. Some Junkers Ju.52/3m had also installed that hoop and the British used a similar technique in some Vickers Wellington bombers.

Sources:
1. http://www.historyofwar.org/articles/weapons_blohm_und_voss_bv_138.html
2. https://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_138
3. https://www.valka.cz/Blohm-Voss-BV-138-C-1-t6475
4. Wydawnictwo Militaria 64 - Blohm & Voss Bv 138 (Translated)

Blohm & Voss BV.138, part two

As we said in the last post about the BV.138, the first prototypes were redesigned in 1938 due to stability problems both in air and water.
The new design shared the basic layout of the first two prototypes but with a longer hull, larger tail surfaces and stronger booms. The first of the redesigned aircraft was designated as BV.138A-01 and was followed by five more pre-production aircraft which were armed with one 20mm MG FF in the frontal turret, and flexibly-mounted rear-firing 7,92mm MG 15 machine guns. One just behind the central engine and another one at the back of the hull with a restricted field of fire thanks to the twin booms and the horizontal section of the tail. It could also carry up to three SC50 bombs under the root of the starboard wing.
The five pre-production aircraft were followed by twenty-five A-1 production aircraft, which flew for the first time in April 1940, the first two of which took place in the Invasion of Norway, but the type didn't really enter service until October-November 1940.
There were some variants apart from the BV.138A. The second version, the BV.138B. This variant was an strengthened version powered by three Junker Jumo 205D engines which yielded 880hp of power. It was armed with two 20mm MG 151/20 cannons, one of them placed in the frontal turret and another one in a rear turret plus the usual 7.92 MG 15 defensive machine gun placed behind the central engine. It could carry 150kg (330lb) of bombs below the root of the starboard wing or four times that payload at maximum overload weight. A total of 18 machines of this variant were produced with one of them being the pre-production one, designated BV.138B-0 and the rest BV.138B-1.
All of them, both A and B variants were manufactured at Blohm & Voss Abt. Flugzeugbau, in Hamburg in a production period ranging from 1939 to 1940 for the A variant and 1940 to 1941 for the B variant.
Due to the lack of available drawings and blueprints, we've only could draw the C variant which physically doesn't differ too much from both A and B variants.

Sources:
1. http://www.historyofwar.org/articles/weapons_blohm_und_voss_bv_138.html
2. https://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_138
3. https://www.valka.cz/Blohm-Voss-BV-138-A-1-t59211
4. https://www.valka.cz/Blohm-Voss-BV-138-B-1-t59212
5. Wydawnictwo Militaria 64 - Blohm & Voss Bv 138 (Translated)

Messerschmitt P.1091

The Messerschmitt P.1091 was a series of projects to convert a regular Bf.109G into a high altitude fighter.
The project began in May 1942 when the Reich's Air Ministry announced the need for a new high altitude fighter which should be operational for late 1944, in order to counter the threat of the American B-29 bomber, which thanks to its high service ceiling, was out of reach of German fighters.
Messerschmitt offered a design based on the Bf.109H (a high altitude variant of the regular Bf.109), called P.1091. The design was, in fact, a stretched version of the 109 where the wings and the rear fuselage were enlarged.
The P.1091 Stuffe I (Stage I) was to quickly produce an aircraft that could reach theoretical altitudes of 17.000 m high (55.750 ft). The Stuffe I was to be powered by a modified turbocharged Daimler Benz DB 605 and armed with three 20mm MG 151 cannons.
By July 1943 it was thought that a higher operational fighter would be necessary, so the P.1091 Stuffe II was proposed to be powered by a Daimler Benz DB 628 high altitude engine with a pressurized cockpit, however, as shortly later, in August 1943, design work on the Stuffe III began.
The Stuffe III's design was similar to the Stuffe I's one but powered by the DB 603U engine or the DB 632. The DB 632 was a modified DB 603 to drive two contra-rotating four-bladed propellers.
As it was obvious that the designs couldn't be materialised within a reasonable amount of time, the RLM transferred every design work to Blohm & Voss, however, Messerschmitt continued work on a high altitude fighter, this time based on the Me.209.
Apparently, to test the DB 628 engine, a mock-up of the engine installation was made in a Bf.109G V49, which was based on a Bf.109G-5. The DB 628 was flight-tested in the Bf.109 V-50 and V-54. After the tests with the V-54, Messerschmitt abandoned every project with the DB 628 engine and the P.1091 was definitely cancelled in mid 1944.

Sources:
1. http://me109.airwar1946.nl/family/1091.htm
2. Midland Publishing - Luftwaffe Secret Projects - Fighters 1939-45
3. AJ Press - Monografie Lotnicze 44 - Messerchmitt Bf.109 Cz.3 (translated)

Blohm & Voss BV.138, part one

The Blohm & Voss 138 was a World War II German trimotor flying boat that served as the Luftwaffe's main seaborne long-range maritime patrol and naval reconnaissance aircraft.
It was originally developed by the Hamburger  Flugzeubau and the prototypes were initially denominated as Ha.138 V1, and Ha.138 V2 which were completed on 15th July 1937 and August 1937 respectively, although they weren't tested until November that year.
Their appearance was unique with its combination of unusual design features with its twin boom tail unit, short fuselage and trimotor engine configuration. The short hull with its hydrodynamic step beneath and flat sides, earned it the nickname "Fliegender Holzschuh" - the flying clog-.
The three prototypes were powered, by three Junkers Jumo 205C which yielded a power of 592hp each and, unlike production versions, like the Bv.138A, they drove three-bladed propellers each.
Eventually it came to be the most numerous aircraft manufactured by the Blohm & Voss which was a shipbuilding company and founded its aircraft subsidiary, the Hamburger Flugzeubau on 4th July 1933 under the control of Walter Blohm. Their first aircraft, the Ha.135 was a conventional biplane trainer which was designed by Reinhold Mewes, but he was soon replaced by Dr. Ing. Richard Vogt who was responsible for many of Blohm & Voss designs. From 1933 to 1937 their aircraft carried the Ha. designation, but that changed to Bv. in 1937. As that changement took place during the development of the Bv.138, the prototypes were known as Ha.138 and the production aircraft as Bv.138.
It was the first flying boat to be produced by Blohm & Voss which previously had examined a series of possible designs before project P.12 was selected as the basis for a long-range reconnaissance aircraft. The original design had shorter hull and a high mounted wing with twin engines, booms and floats attached to the wings.
A mock-up was built in early 1935 and Blohm & Voss was awarded by the Reich Air Ministry with a contract to produce three prototypes, each to be powered by a different type of an engine that could reach 1000hp. All three of the engines ran into design problems and Vogt was forced to redesign the aircraft using the aforementioned trio of Junkers Jumo 205C engines with the third engine mounted above the centre of the wing. These engines, in this configuration, produced almost the same amount of power as two 1000hp engines, but the third one produced extra weight and drag.
Those first prototypes had short hulls, smaller tail surfaces and narrow booms. Testing revealed that they were unstable both in the air and in the water, so a complete redesign was imposed, which began in 1938.

Sources:
1. https://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_138
2. https://en.wikipedia.org/wiki/Hamburger_Flugzeugbau
3. http://www.historyofwar.org/articles/weapons_blohm_und_voss_bv_138.html
4. https://www.valka.cz/topic/view/59211/Blohm-and-amp-Voss-BV-138-A-1