+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based historical facts. BEWARE!
Some background:
The Fokker D.XX fighter was designed in 1935 by Dutch aircraft manufacturer Fokker as a conservative export alternative to the D.XXI monoplane. The latter had been developed in response to requirements laid out by the Royal Netherlands East Indies Army Air Force (Militaire Luchtvaart van het Koninklijk Nederlands-Indisch Leger, ML-KNIL), but Fokker saw a good deal of market potential for the aircraft in Europe, too, but was afraid that many smaller European air forces still preferred conservative biplane designs.
As a consequence, the D.XX was developed in parallel to the D.XXI and both aircraft shared many components, primarily the fuselage and the tail section. Like its D.XXI stablemate the D.XX biplane was designed as an inexpensive, rugged, and compact fighter aircraft that would possess respectable performance for its era.
Following standard Fokker design practice of the period, the D.XX featured a welded steel tube fuselage that was largely covered by fabric, including the flight control surfaces, but elements forward of the trailing edges of the wings were covered by detachable aluminum panels instead. The wings were of a wooden construction, being composed of two box spars attached to ribs made of plywood, and covered by fabric, too. The aircraft was outfitted with a fixed, spatted undercarriage with cantilever legs, and braking was provided by independently-operated pedals using compressed air.
The cockpit of the D.XXI was fully enclosed by a plexiglas hood featuring large sliding sections. The canopy was entirely jettisonable in an emergency situation to enable pilots to bail out. Pilots were protected against turnover injuries by means of a pylon built into the structure of the aircraft set behind the seat. Fuel was housed in a 77-gallon tank located aft of the engine, and an auxiliary fuel tank could also be installed behind the pilot seat.
Main armament consisted of two pairs of 7.92mm M36 FN-Browning machine guns, two being housed within the forward fuselage above the engine, requiring the latter to be synchronized in order to shoot through the propeller blades, and another pair was carried in fairings under the lower wings, outside of the propeller arc.
Initially, the Fokker D.XX was powered by the 830 h.p. Bristol Mercury VII or VIII engines, but for export customers a number of alternative engines were considered, too. These included such power plants as the 650 h.p. Rolls-Royce Kestrel V and the 750 h.p. Pratt and Whitney Twin Wasp Junior. There were even plans to mount the 1,050 h.p. Rolls-Royce Merlin and the 1,090 h.p. Daimler-Benz DB 600H, both coupled with a radiator installation under the fuselage.
However, interest in the Fokker D.XX was low, since the monoplane promised much superior performance and future development potential. Compared with the Fokker D.XXI, the D.XX lacked top speed and acceleration, but it had, thanks to its much bigger wing area, a better rate of climb and was the superior dogfight aircraft.
Anyway, with the D.XXI as direct in-house competitor and very similar aircraft like the Gloster Gladiator on the market, Fokker's last biplane aircraft was not a success. A major contract with Sweden for an initial batch of 30 aircraft and rights for further license production did not materialize. Other prospects, e. g. Lithuania, Latvia, Greece, Egypt and Yugoslavia, settled upon aircraft of British production, and in the end only Norway and Denmark bought the biplane fighter.
Total production, including two prototypes and three pre-production aircraft, only reached a mere 46 machines, and none of them survived the first months of the 2nd World War.
General characteristics:
Crew: one
Length: 8.2 m (26 ft 11 in)
Wingspan: 10.6 m (34 ft 8 ½ in)
Height: 2.92 m (9 ft 7 in)
Wing area: 28m² (300 sq ft)
Empty weight: 1,594 kg (3,514 lb)
Loaded weight: 4,594 lb (2,088 kg)
Powerplant:
1 × Bristol Mercury VIII 9-cyl. air-cooled radial piston engine, 620 kW (830 hp)
Performance:
Maximum speed: 253 mph (220 knots, 407 km/h) at 14,500 ft (4,400 m)
Cruise speed: 338 km/h (210 mph; 186 kn)
Stall speed: 85 km/h (53 mph; 46 knots)
Range: 930 km (578 mi; 502 nmi)
Endurance: 2 hours
Service ceiling: 11,350 m (37,240 ft)
Rate of climb: 11.7 m/s (2,300 ft/min)
Climb to 10,000 ft (3,050 m): 4.75 min
Power/mass: 0.309 kW/kg (0.188 hp/lb)
Armament:
4× 8 mm (0.315 in) machine guns with 500 RPG in the fuselage and 300 RPG under the lower wings
The kit and its assembly:
I had found the spare wings from a Gloster Gladiator in my donor bank, and wondered what I could do with them - and eventually stunbled upon a PM Model Fokker D.XXI. Why not retrograde this early monoplane fighter into a biplane, with relatively modern features?
Said and done, and the respective conversion/kitbashing was a rather straightforward affair, even though not without some challenges.
The biggest issue became the lower wings: the Gladiator wings are much thinner and have less depth than the original Fokker wings, so that much of the wing roots on the fuselage had to be sanded away. This resulted in gaping openings, which had to be filled, including a resculpted trailing edge intersection. Not a complicated feat, but messy.
Another issue arose through the fact that the D.XXI's fuselage is wider than the Gloster Gladiator's - resulting in a wider span of the lower wings than the upper! In order to correct this, the lower wings' tips were clipped and I used the occasion to re-sculpt all wing tips, trying to get away from the Gladiator's characteristic round shape.
Once the lower wings were mated with the fuselage, the upper wings were added with the help of the outer support struts only. Once dry, the additional struts between the upper wing and the fuselage were added - the latter were scratched with styrene strips. Thin styrene was also used to add some diagonal bracing struts, once more in an attempt to change the wings' look away from its Gladiator origins.
The spatted wheels were taken from the PM Model kit, but shortened by 2mm - OOB they are IMHO much too long, and the result would be a very stalky stance. The tail wheel was also taken OOB, but moved aft and shortened, too.
Inside, a different seat was used; a box was placed behind it, filling the gap, and a dashboard was added under the windshield. The canopy (very thick material!) was cut into three pieces, for a potential open presentation.
Engine and cowling were taken OOB, but the propeller was replaced with a better-looking scrap box find, which also received a longer axis for better balance and free spinning.
The rigging was done with material derived from heated, black IP sprues, which I like because it bonds well with the kit's plastic and can be attached with standard glue. Additionally, the wire's strength can the individually tailored.
Painting and markings:
I used this occasion to apply the somewhat obscure camouflage of the Royal Danish Air Force from the late Thirties. While the scheme itself is rather simple, the colors remain obscure. In profiles and painting instructions you can find a wide range of recommendations - ranging from sand or a greenish yellow and olive drab to dark green and dark earth! The undersides were supposed to be "bluish grey".
I eventually settled upon a relatively simple choice, with Humbrol 83 (Ochre) and Revell 46 (NATO Olive Drab, RAL 7013 a.k.a. Gelboliv), which looks almost like a dark brown together with the greenish sand tone. IMHO they make a good combo for the Danish scheme. For the undersides, I went for Humbrol 128 (FS 36320). Interior surfaces were painted in a dark slate grey tone, the propeller received an aluminum front and flat black back surfaces.
The kit received a light black ink wash and a post-shading treatment with various shades of the basic tones, including ModelMaster RAL 7028 (German WWII Dunkelgelb) as well as Humbrol 155, 163 and 247. Finally, the fabric structure on the wings was slightly emphasized with dry-brushed light grey, and exhaust soot under the fuselage was added with grinded graphite.
The markings come from various sources: roundels from a D.XXI sheet from PrintScale, the flags on the fin belong to a Danish F-100 (XtraDecal) and the tactical code was puzzled together. The nose art, the charging knight on the cowling, which I added because I found the overall aircraft to look pretty bleak, comes from a ModelCollect tank model sheet.
Finally, the whole kit was sealed with matt acrylic varnish (Italeri).
Not a spectacular whif, and this one does not really stand out between similar builds (e.g. the Macchi Brezza or the Gloster Glaive) I did before, but I find it interesting how good and plausible the retrograded Fokker D.XXI looks. The new/old wings blend in nicely, and the Danish scheme looks good on this biplane, too, even though I wonder why these colors were chosen? It looks rather like a desert paint scheme than something for Northern Europe, with lots of water and mostly green, flat landscape?
