Fokker G.I Heavy Fighter

While researching some upcoming articles that I’m working on, I came across a fascinating WWII aircraft, the Fokker G.I. I am familiar with Anthony Fokker, “The Flying Dutchman,” and many of his designs, but the G.I caught me by surprise. Maybe it’s my love for his initial designs during WWI, such as the Eindecker, or to get my heart pounding, the Dr.I triplane that I associate the Fokker name to and clouds my vision of the many aircraft that he produced.

General view of the exhibition hall during the assembly of airplanes, incl. 
Letov from Czechoslovakia, Koolhoven from the Netherlands, Caudron-Renault from France. 
On the left, a fragment of the reconnaissance aircraft of the French production Caudron C.600 Aiglon is visible. November 1936. (Photo & description courtesy,

The Palais de l’Air (Paris Air Show) of 1936 is the fifteenth exhibition since its inception in 1908 and showcased the modern aircraft construction techniques where the newly prototyped but never flown Fokker G.I is proudly displayed. Perched high upon welded steel wing stands positioned between Russian and Polish airplanes, the Fokker G.I gained the most attention because of its heavy armament.

Two rapid-fire 23 mm Madsen cannons along with two 7.9 mm machine guns reside in the nose, and one moveable 7.9 mm machine gun protects the rear section of the transparent cone-shaped fuselage.

Fokker G.I Flyer (Photo courtesy,

This twin-engine aircraft with its streamlined fuselage nestled between two tail booms supporting a single rear horizontal stabilizer with twin rudders is a sight to see and leaves a lasting impression! The plane earned several nicknames during the show where the British referred to it as the “Reaper,” and the French called it the “Le Faucheur” or “Mower.” Though some suggest, Mr. Fokker nicknamed it the “Mower” himself, and I can see why. I would hate to see that coming at me in my 6!

Anthony Fokker (courtesy

Mr. Fokker and his team of designers anticipated a large turnout that year and hoped to spark the spectator’s interest with their new aircraft, and in true Fokker fashion, his G.I is the prodigy of the show! Written by the flight correspondent on the eve of the show;

“Never in the history of flying has the technique of aircraft construction stood so high; the days of stick-and-string contraptions are over, and real engineering has taken their place. The art of designing aero engines has also improved very materially, with the result that power has gone up and weight down. Reliability, once a doubtful quantity, is now taken for granted.”

The G.I prototype painted green with a medium blue belly, designated X-2, first flew on March 16, 1937, from Welschap airfield, near Eindhoven, Netherlands, piloted by a Czechoslovakia pilot. It was a successful flight lasting for about 20 minutes until landing safely without any problems. Testing continued, and after four flights, some issues did arise on the fifth flight with one of the supercharged Hispano Suiza engines overheating due to a design flaw in the oiling system. Engine damage resulted from insufficient lubrication to the extent of broken parts exiting the exhaust and damaging one of the tail booms. Frustrated with the Hispano Suiza engines’ known issues, Mr. Fokker attempted to add extra oil coolers underneath each powerplant. Still, it had little effect on lowering the temperature, and he decides to replace the engines entirely with the more reliable Pratt & Whitney R-1535 Twin Wasp Junior known as the Fokker G.I “Wasp” version. He also produced the Fokker G.I “Mercury” version for the Dutch, where larger Bristol Mercury VIII engines rated at 850 hp replaces the less powerful and smaller 750 hp Pratt & Whitney R-1535.

Men inspecting the rear turret on a Fokker G.I X-2. (Photos courtesy,
Check out this video that I narrated and added a sound track. (The original was silent.)

*My brother Doug brought to my attention that he noticed in the video the Fokker G.I. X-2 prototype has counter-rotating propellers. I was unaware of that, and I thank him for pointing it out. He also said that he could see the propellers’ rotational direction in the photos of the X-2. The news piqued my curiosity, so let’s have a look into why Mr. Fokker designed it this way, and I’ll discuss it at the bottom of this post.

Mr. Fokker received the first production orders for the G.I “Wasp” from the Spanish Republicans just before the beginning of the Spanish Civil War that started on July 17, 1936, and lasted until April 1, 1939. The Republicans contacted him looking for a good fighter plane for the looming civil war. He told them about a new fighter plane that his design team started working on in 1935 for the French Airforce but later rejected when other French designs seemed more practical. Mr. Fokker saw potential in this new design and continued developing the prototype, referred to as “project 129.” The Republicans, in dire need of a fighter airplane, ordered 26 planes, even before Mr. Fokker could complete a test flight. Because of the signing of the Non-Intervention Agreement in August 1936 that places an embargo against the fighting parties, Fokker suspends the order and focuses his attentions on the upcoming Paris Air Show in November that same year. He did continue to build those 26 aircraft and later told the press that Finland is interested.

Servicemen in front of a Fokker G.I “Mercury” (Photo courtesy,

Soon after the test flight, the Dutch Army Aviation Group (Luchtvaartafdeeling or LVA) ordered 36 Fokker G.I “Mercury” airplanes and received delivery in 1938 with aircraft registration numbers 300 through 335. This airplane differed slightly from the prototype with the installation of the Bristol Mercury VIII engines. Most importantly, as requested by the LVA, eight fixed 7.9 mm Browning machine guns to be installed in the nose and one moveable 7.9 mm Browning machine gun mounted in the rear. Also, provisions to be able to carry a bomb load of 400 kg if desired.

Fokker G.I with hatches open (Photo courtesy,
Fokker G.I “Mercury” 312 (Photos courtesy,

The Fokker G.I “Mercury” has a wingspan of 17.16 m(56 ft), a length of 10.89 m(36 ft), and an overall height of 3.35 m(11 ft). The unladen weight is 3360 kg(7408 lbs) with a gross weight of 4800 kg(10,582 lbs). It can reach a maximum speed of 475 km/h(295 mph) and a cruising speed of 356 km/h(221 mph) with a service ceiling of 9300 m(30,511 ft). A flight range of 1410 km(876 miles) is possible with full fuel tanks carrying 550 liters(145 gallons) plus 150 liters(40 gallons) in reserve at cruising speed.

Fokker G.I “Mercury” 302 fitted with dive brakes at Soesterberg. (Photo courtesy,

The aircraft completed missions in their 3rd and 4th JaVA (Fighter Flight Department) used as a hunting/cruiser airplane. Initially, the Dutch intended to use them as a dive bomber aircraft but decided not to because it performed better configured as a fighter plane. Some testing included fitting dive brakes on aircraft number 302, similar to those found on the Junkers Ju 87 or Stuka, but showed poor results on the Fokker G.I “Mercury.” Other variants included setting up aircraft number 304 as a scout by installing an observation dome or “Bathtub” under the hull, but proved unsuccessful. I can imagine the extra drag and weight created significantly reduced flight performance.

Fokker G.I “Mercury” 304 Reconnaissance Scout (Photo courtesy,

The Fokker G.I “Wasp” version is similar to the “Mercury” version but with the smaller, lighter, and less powerful 750 hp Pratt & Whitney R-1535 Twin Wasp Junior engines. The nose armament is reduced to four fixed 7.9 mm Browning machine guns but still retains the single movable 7.9 mm Browning machine gun in the rear. This airframe is slightly shorter than the “Mercury,” with an overall length reduced to 10.30 m(34 ft) needed to adjust for the center of gravity. The unladen weight diminishes to 3150 kg(6945 pounds) with a decreased gross weight of 4400 kg(9700 pounds). While maintaining a cruising speed of 322 km/h(200 mph), the pilot can expect a flight range of 1580 km(982 miles), and at full-throttle will result in a maximum speed of 434 km/h(269 mph). Both Fokker G.I versions operated with a flight crew of two but had an optional “middle seat” for a third crew member, but rarely used. Through testing, the aircraft performed better with a flight crew of two. Fokker produces 26 G.I “Wasp” aircraft and assigned registration numbers 341 through 365.

Fokker used his proven mixed construction technique in building the G.I with a combination of welded steel tubing covered with removable aluminum panels for the nose armament, front cockpit, and engine nacelles. The fuselage’s rear consisted of a wooden frame covered with thin plywood and Perspex windows, a clear acrylic, hung in aluminum frames. The rear conical turret is capable of turning 360 degrees for the gunner.

Fokker G.I Under Construction (Photo courtesy,

Aluminum framing and removable panels form the wing roots and contain the oil tanks along the leading edges and the middle section’s fuel tanks. Fokker also constructs the twin tail booms, horizontal stabilizer, and twin rudders from aluminum. Past the engine nacelles, the outer wing development consists of wooden framing and plywood covering. The wing spars run through the cockpit behind the pilot and fore of the rear gunner turret providing maximum support. Steel frames covered with linen make up all of the controlling surfaces. This mixed construction technique is a standard Fokker process and became characteristic of their cantilever high-winged monoplanes such as the Fokker F.VIII in the late 1920s.

In April 1940, the Dutch Ministry of Defense purchased the remaining 26 Fokker G.I “Wasp” aircraft leftover from the Non-Intervention Agreement signed in 1936 involving the Spanish Republicans. They were supposedly going to Finland after that cancellation but never left the Netherlands. Most were incomplete and stored in multiple hangers in various locations, but the JaVA were able to complete some ready for service in a short time.

Fokker G.I Advertisement (courtesy
Fokker G.I “Mercury” (courtesy

In the early morning on May 10, 1940, Germany invaded the Netherlands with the Luftwaffe attacking the Dutch airfields. The battle was fierce and devastating to both JaVa divisions, and on May 14, the Dutch surrender. The Germans seized the remaining Fokker G.I airplanes and were taken into service by the Luftwaffe as testing and training aircraft.

A crashed Fokker G-1 with on the nose in the foreground the emblem of a duck with a button on its neck, the emblem of the 3rd JaVA (Fighter Flight Department) which on
Waalhaven airfield was stationed. (Photo & description courtesy,
Luftwaffe soldiers at a captured Fokker G-1 Wasp, now equipped with Luftwaffe crosses, at Waalhaven airfield (Flugplatz). (Photo & description courtesy,
Wreckage of a Fokker G.1 Mercury of the 4th JaVA at Bergen in front of Hangar 6. Left front. (Photo & description courtesy,

None of the original Fokker G.I survived the war with only a few pieces found not worth saving, but a replica is proudly on display at the Dutch Nationaal Militair Museum (National Military Museum) in Soesterberg, Netherlands. I hope to visit this place someday and enjoy first hand the true beauty of this Fokker design!

A replica of a Fokker G.I on display at the Dutch National Military Museum. (Photo courtesy Nationaal Militair Museum)

*The term “counter-rotating propellers,” is used when a twin or multi-engine aircraft has propeller(s) on one wing that spins in the opposite direction of the propeller(s) on the other side. The primary purpose is to remove any potential issues related to a “Critical Engine” situation by balancing the torque output between the engines along the vertical axis.

The definition of a “Critical Engine” on a multi-engine airplane would be the engine that would cause the most significant impact upon the aircraft’s performance and handling if it were not in operation. A “Critical Engine” does not exist on multi-engine aircraft with counter-rotating propellers that spin towards the fuselage looking at the propeller’s top while seated in the cockpit, like on the X-2. A good reason why Mr. Fokker set up the G.I this way, and I understand his reasoning.

When counter-rotating propellers spin away from the fuselage, the opposite is accurate, and both engines are critical. A prime example is the Lockheed P-38, but I’ll save that for a future post.