Tag Archives: Experimental

Focke Wulf Fw 190 mit DB 609

Nazi flag Nazi Germany (1942)
Fighter Concept – None Built

An alternate side view of the Fw 190 mit DB 609 model. [Falko Bormann]
The Focke-Wulf Fw 190 mit DB 609 was a 1942 design venture to provide the Luftwaffe with a successor to the Fw 190 and its troublesome BMW 801 radial engine. Intended, to mount the envisioned experimental 16-cylinder Daimler-Benz DB 609 engine to produce around 2,600 hp (later 3,400 hp), the new power plant would have required a drastic redesign to the forward section of the Fw 190 as well as parts of the fuselage. In the end, the Fw 190 mit DB 609 was canceled due to flaws with the design and Daimler-Benz’s cancellation of the DB 609 project. Similar to many of the other designs produced in 1942, the Fw 190 mit DB 609 remained a paper design only, although an airframe was provided for the intent of mounting and testing the engine. Obscure in nature and short-lived, much of the project’s specifications and estimated performance are unknown.


The original blueprint illustration of the Fw 190 mit DB 609. [War Thunder Forums]
The Focke-Wulf Fw 190 Würger (Shrike) was one of Nazi Germany’s most iconic fighters of the Second World War. First introduced in August of 1941, the Fw 190 gave contemporary Allied fighters a run for their money and proved to be a relatively successful design. However, the air-cooled 14-cylinder BMW 801 radial engine which powered the Fw 190 proved to be troublesome at times. The BMW 801’s cooling system was inadequate, which caused overheating and production of fumes, which would leak into the cockpit and could suffocate the pilot. Despite the relatively successful introduction of the Fw 190, it was not known if the Reichsluftfahrtministerium (RLM / Ministry of Aviation) would make further orders for the aircraft. However, the spring of 1942 was a prosperous time for the Focke-Wulf firm and assured the Fw 190’s future. The RLM put in orders for large quantities of Fw 190, which in turn boosted the firm’s budget. As such, designers at the Bremen-based Focke-Wulf firm initiated a design venture to produce a successor for the Fw 190 by replacing the troublesome BMW 801 engine with more advanced engines being developed by BMW and Daimler-Benz.

As such, the Focke-Wulf firm produced several drawings in late 1942 which saw the Fw 190 mounting experimental engines. The designs are as follows:

Drawing Number Project Title
10 10 05-201 Fw 190 mit BMW P. 8028
10 10 05-202 Fw 190 mit BMW 801 J
10 10 05-203 Fw 190 mit DB 609
10 13 141-02 Fw 190 mit DB 623 A
10 13 141-16 Fw 190 mit DB 614
11 19 05-502 Fw 190 mit BMW P. 8011
Unknown Fw 190 mit DB 603
Unknown Fw 190 Strahljäger

In order to provide a suitable testbed for these engines, Fw 190 V19 (Werknummer 0042, rebuilt from a Fw 190 A-1) was allocated for engine installation tests. Curiously enough, Fw 190 V19 would be later be redesigned for the “Falcon” wing design which saw a drastic redesign of the wing to a swept, bent design. Conversion to this wing type was meant to take place on February 16, 1944 but this would never occur. Nonetheless, Fw 190 V19 would maintain the regular wings for engine testing.

A closeup of the Fw 190 mit DB 609 model’s cockpit and fuselage section, highlighting the supercharger radiator’s placement. [Falko Bormann]
Although the Fw 190 mit DB 609 showed potential, there were several problems which plagued the design. For one, the rather heavy and bulky engine severely affected the aircraft’s center of gravity. As such, the engine’s radiators had to be moved down the fuselage behind the cockpit. The engine also would have put too much stress on the landing gears which could potentially result in a fatal crash if landing conditions were rough. On top of the airframe design issues, the intricate design of the engine also proved a problem for the Daimler-Benz designers, who would terminate the DB 609 (and its subprojects) in April 1943. As such, the Fw 190 mit 609 project would be dropped as well without the experimental engine ever being mounted on V19. Many of the other designs produced by Focke-Wulf in 1942 would also meet the same fate, for more or less similar reasons.

Due to the short-lived conceptual nature of the design, detailed specifications and estimated performance do not appear to have survived. As such, much of the aircraft’s intricate details and specifications are unknown. One could only hope that, in the near future, more details of the Fw 190 mit DB 609 and it’s contemporary designs will surface.


A model of the Fw 190 mit DB 609 in a hypothetical livery with a drop tank. [Falko Bormann]
The Focke-Wulf Fw 190 mit DB 609 was a 1942 project to produce a successor to the Fw 190 by replacing the troublesome BMW 801 engine with more promising experimental engines being developed at the time. As the name of the project suggests, this design would have seen the implementation of a Daimler-Benz DB 609 V16 engine. The Daimler-Benz DB 609 was a development of the company’s DB 603 engine. Unlike its predecessor, the DB 609 would have 16 cylinders in contrast to the former’s 12 cylinders. The DB 609’s output was estimated by Daimler-Benz designers to be approximately 2,600 to 2,660 hp, though it would later be upped to 3,400 hp. The benefits of this engine were the ability to function normally upright and inverted, but the bulky engine design required a drastic redesign of the engine cowl and parts of the fuselage. The cowl would have been extended to accommodate the DB 609 engine, the length of which would have measured at 115 in / 2,935 mm compared to the BMW 801’s 79 in / 2,006 mm length.

According to the official blueprints for the Fw 190 mit DB 609, the two large radiators intakes required for the engine’s supercharger were moved to the cockpit’s rear, on the side of the fuselage. This was done to pull the center of gravity back, as placing them in the front would make the aircraft too nose heavy. The placement of the supercharger radiators is similar to that of the American Republic P-47 Thunderbolt. It would appear that internet sources claim the radiator placement was nicknamed the Hamsterbacken (Hamster Cheeks), but it is unknown whether or not this was an official nickname.

Fw 190 V19 (Werknummer 0042), which was intended to mount and test the DB 609 engine, was rebuilt from a Fw 190 A-1, but it is unknown which variant precisely the hypothetical production variant would be based upon. Armament wise, the official project blueprints show two 7.92x57mm Mauser MG 17 machine guns mounted on top the engine cowl. What appears to be a 20x82mm Mauser MG 151/20 cannon would be installed in the engine hub and would fire out through the propellers. It is unknown what wing armament (if any) the Fw 190 mit DB 609 would have had.

Due to the rather short-lived and conceptual nature of the Fw 190 mit DB 609, not many of the plane’s specifications are unknown. Performance estimations do not appear to be available, nor are aircraft dimensions.


  • Nazi Germany – The Focke-Wulf Fw 190 mit DB 609 was intended to be a successor to the Fw 190. However, development was dropped due to various problems with the design and engine.


Artist Concept of the Fw 109 with the DB 609 Engine [Ed Jackson]
A retouched blueprint of the Fw 190 mit DB 609. [Heinz J. Nowarra]

Akaflieg Berlin B9

Nazi flag Nazi Germany (1942)
Experimental Aircraft – 1 Prototype Built

Three-quarters view of the B9, note the large glazed cockpit. Colorized by Michael Jucan [airwar.ru]
The Akaflieg Berlin B9 was a German experimental twin engine aircraft designed with the pilot placed in the prone position.  It was designed to withstand extremely high g-forces. One prototype was built and tested by a glider production workshop in 1943 but it would not be adopted for mass production. The author would like to especially thank Carsten Karge from the Archiv Akaflieg Berlin for providing information on this generally unknown aircraft.

Why prone position?

During sharp up and down turns while flying an aircraft, strong g-forces appear that act on the pilot, potentially leading to loss of consciousness. Under normal flying conditions, the g-forces that appear are relatively harmless. The first effect of the g-force which the pilot notices is the difficulty of moving his body normally, as normal movements feel much heavier. Another effect of strong g-forces, which is much more dangerous, is the loss of oxygen flow to the brain. In some cases, the flow of oxygen and blood to the human brain can be greatly diminished, which can lead to the pilot losing consciousness momentarily. This effect lasts a short time, but it is enough for the pilot to lose control of the plane with a potentially fatal outcome.

While today, devices such as advanced anti-g suits help the pilot withstand strong g-forces, during the World War Two, other solutions had to be found. The Germans had noticed that, especially during sharp dive bombing actions, the pilots often lost consciousness. One way to tackle this was to put the pilot into a prone position, which in essence means to fly the plane while lying on the belly. In this position, the pilot has both his heart and his brain at the same level, which means that blood is no longer stopped from travelling to the brain during high-g maneuvers. Thus, this flying position allows the pilot to endure much greater g-forces than he would normally be able to if he would be in an ordinary sitting position. Other advantages of the prone position are the reduced aircraft size, smaller fuselage, less drag due to the smaller cockpit, and it would be easier for the pilot to operate the plane when conducting bomb sighting and ground attack, among other advantages.

During the war, the Germans would test several such aircraft designs, sush as the Henschel Hs 132 or B9, mostly for the ground attack role. Beside a few prototypes built, none were ever used operationally.


The SF 17 prone glider was the forerunner of the B9 powered aircraft [Akaflieg Stuttgart]
In order to test the idea of an aircraft with the pilot in the prone-position, the Aero-Technical Group (Flugtechnische Fachgruppe/FFG) of Stuttgart designed and later built the FS 17 all-wood test glider. It was especially designed to withstand forces up to 14 G. It made its first test flight on 21st March, 1938. In the spring of 1939, FFG Stuttgart made the first design drawings and calculations for a prone-piloted aircraft. This aircraft was to be powered by two Hirth HM 50 engines with an estimated speed of 250 mph (400 km/h).

FFG Stuttgart never completed this project as it was forced, for unknown but likely politicaly reasons, to hand over the project to Akaflieg (Akademische Fliegergruppe/Academic Aviator Group) Berlin. It is possible the order came from the German Experimental Department for Aerospace (Deutsche Versuchanstalt für Luftfahrt e.V. Berlin-Aldershof) DVL or even from the Ministry of Aviation (RLM – Reichsluftfahrtministerium), but precise information is lacking. Akaflieg Berlin, founded in 1920, was one of the oldest gliding clubs in Germany and it still exists today.

The RLM designation for this aircraft was “8-341” but Akaflieg used the simpler B9 designation. The technical characteristics that the new plane was supposed to have were a good field-of-view for the pilot in the prone position, a high degree of safety for the pilot, a high speed during diving, good general flying characteristics and being able to withstand forces of up to 25 G, or 22 G depending on the sources.

Akaflieg Berlin had a small number of engineers and workers and an adequately equipped workshop to complete the task given. For this purpose, a design team was formed with Theodor Goedicke, Leo Schmidt and Martin G. Winter, which was responsible for the creation of this new aircraft design. The first prototype was to be ready by August 1942 but this was never achieved, and the prototype was only completed in early 1943. It made its first test flight on the 10th April, 1943 at the Schönefeld airfield, near Berlin.

The Design

Front view of the B9 [airwar]
The B9 was a single-seat, low wing, mixed construction aircraft with the pilot in prone position. It consisted of a metal airframe, made of steel ribs, covered with wood and canvas. The main fuselage’s cross-section was trapezoidal shaped. As the B9 was specifically designed to withstand forces of up to 25 G, it had to have a strong fuselage.

The wings were made of wood covered with duralumin sheets. In order for the wooden wings to withstand the strong torsional forces which occur during high acceleration maneuvers, the spaces between the spars were heavily reinforced. The middle part of the wings viewed from above have a square shape and then narrow towards the wing tips. The wings were held in place by four bolts on each side. The rear tail design was a simple one, with standard rudder and elevators.

The B9 had a standard retractable landing gear copied from the Me-108, which consisted of two larger wheels and one smaller non-retractable wheel at the back. The landing gear was lowered and raised manually. The front wheels retracted into the engine nacelles, but they were not fully enclosed.

The B9 had a large 4.9 ft (1.5 m) long glazed cockpit with good all-around view. But, as the pilot was in a prone position, the above and the rear views were limited by the human body’s inability to turn the head in these directions. The glazed cockpit was made of two parts, the front windshield and the rear larger canopy that opened to the right side. The cockpit interior had to be especially designed for a pilot lying in the prone position. The usual flight controls were almost useless in this situation and, thus, certain changes were necessary. It was important to divide the controls on both sides of the cockpit, in order to avoid the pilot crossing hands, which could lead to complications in flight. On the right side were the controls for ailerons and elevation. The pilot would use his right hand to gain access to the harness and the canopy release mechanism. For controlling the rudders and brakes, the pilot would use his feet. Using his left hand, he would operate the remaining instruments, the throttles, flaps, ignition switches, emergency pump, fire warning, undercarriage control and others. Additional engine and flight instruments were located behind the pilot. These included, among others, the distance indicator, climb indicator, compass, oil and fuel pressure gauges and airspeed indicator. For the pilot to be able to see them, a small mirror was provided. There were also inclined and horizontal line markers on the inner windshield to help the pilot with orientation. For flying at high altitude, an oxygen supply system with a mask was provided to the pilot.

The aircraft was powered by two Hirt HM 500 air-cooled engines, with 105 hp each. The maximum speed was around 140 mph (225 km/h) but, according to some sources, it was as high as 155 mph (250 km/h). The four fuel tanks, with a total capacity of 25 gallons (95 l), were located between the spars on both engine sides. The B9’s effective operational range was 250 mi (400 km). Originally, the B9 was meant to be equipped with two variable-pitch propellers, but it was instead fitted with ordinary wooden fixed pitch propellers made by the Schäfer company.

As the B9 could be used as a ground attack aircraft, a bomb rack was meant to be installed, but it is not clear if this was ever implemented.

Operational Testing

The B9 in flight [airwar]
The operational prototype was ready by the summer of 1943. The first test flights were carried out by Ing. L. Schmidt and Dipl.-lng. E. G. Friedrichs. On one flight, L. Schmidt had an accident, the details of which are not known, but the plane probably suffered only minor damage.

The B9 was meant to make a series of test flights in order to ascertain if the prone position design had any merit and to test the general flying and overall structural performance. If these proved to be successful, the B9 would serve as base for future development and be put into active service. The B9 aircraft received the ”D-ECAY” marking, which was painted on both sides of the fuselage.

The tests were carried out from July to October 1943, during which time around thirty pilots had the opportunity to fly it. The test flights were conducted without any major problems and only one accident was recorded. This accident was caused not by any mechanical problems, but by a pilot mistake during takeoff. The B9 was damaged, but it was repaired and put back into service in only a few weeks.

The pilots did not have many objections to flying in the new prone position. They described it as comfortable and that it was relatively easy to adapt to the new commands. There were some issues, like fatigue and tiredness of the neck and shoulder muscles because of the constant moving of the upper arms. There were also some complaints about the chin supporter, which was deemed as unpleasant during flight but it was essential during high g-force maneuvers. During these test flights, the control panel and the controls did receive some changes in design. The large and fully glazed cockpit provided the pilot with good front and below fields of view, while the rear and upward view was somewhat problematic due to the prone position.

These tests showed that this type of aircraft was well suited for bomber, ground attack, high speed reconnaissance and possibly even in a high-speed fighter role. But it was also noticed that, due to the somewhat restricted view, the use of low speed prone pilot aircraft without air support was not recommended. Despite being designed to withstand forces of up to 25 G, the maximum achieved was only 8.5 G. One of the reasons for this was the use of low rotational speed propellers.

For 1944 and 1945 unfortunately, there is no information about the B9’s operational use. The B9 was found abandoned at the Johannisthal airfield near Berlin after the war. In what condition it was by the time of capture is not known. What is unusual is that the B9 was captured by the Americans and not the Soviets (according to author Hans J.W.). What the Americans did with the plane is unknown to this day, but it was most likely scrapped.

Only one B9 plane prototype was ever built. By 1943 and 44, a large amount of resources were invested in the production of fighters for the defense of the Reich and there were neither the time nor the resources needed to develop and test such an aircraft.

Akaflieg Berlin B9 Specifications

Wingspan 30 ft 10 in / 9.4 m
Length 19 ft 8 in / 6 m
Height 7 ft 7 in / 2.3 m
Wing Area 128 sq ft / 11.9 m²
Engine Two Hirt HM 500 engines, with 105 hp each
Empty Weight 2,207 lbs / 940 kg
Maximum Takeoff Weight 2,458 lbs / 1,115 kg
Fuel Capacity 95 l
Maximum Speed 140 mph / 225 km/h
Range 250 mi / 400 km
Maximum Service Ceiling 13,000 ft / 4.000 m
Climb to 13,125 ft / 4,000 m 4 minutes and 12 seconds
Crew One pilot
Armament None


Illustrations by Haryo Panji https://www.deviantart.com/haryopanji


Akaflieg Berlin B9 – Prototype [Haryo Panji]
B9 drawings [airwar]