+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
Some background:
The Saab B20 was a two-seat dive bomber developed in Sweden during the final phase of WWII, as a higher-performance successor of the company’s own B17 dive bomber which had been introduced in – a robust and effective aircraft, which, due to its limited engine power and poor aerodynamics, was already considered obsolete by late 1944.
The B20 had originally been developed by the Flygtekniska försöksanstalten (National Aeronautical Research Institute) in Ulvsunda around the license-build German DB605B engine, which had become available in , primarily for the new Saab J21 fighter and the B18 bomber. The B20 was a single-engine, all-metal mid-wing monoplane, with a wide-track retractable undercarriage and wing-mounted dive brakes. It had a crew of two: a pilot and a navigator/radio-operator/gunner, seated under a long, glazed canopy which provided good all-round visibility. The pilot was provided with a telescopic bombsight. The SFA-built DB605B was mounted in the nose, with the radiator behind and below a three-blade propeller, giving the aircraft a nose profile that resembled the American Curtiss P-40 Warhawk, even though more elegant and streamlined, to enable a high performance.
The narrow engine offered high aerodynamic efficiency and had a slim fuselage. The landing gear was full retractable and covered and the cockpit greenhouse smoothly blended into the body. Under the wing’s main spar was space for an internal bomb bay, large enough for a single 500 kg (1,100 lb) bomb on a swing arm that kept the dropped bomb away from the propeller disc. The fully closed bay was also wide enough to carry two 250 kg (550 lb) bombs for horizontal, bombing, too, and single bombs of the same caliber could be carried under the wings for a total ordnance of 1.000 kg (2200 lb).
Furthermore the aircraft was armed with two 13.2 mm (0.52 in) akan m/39A aircraft machine guns (Belgian FN Herstal M.1939 machine guns license built by LM Ericsson) with 300 RPG in the nose, synchronized to fire through the propeller, and a defensive 8 mm (0.315 in) ksp m/22 (license-built AN/M2) machine gun with 500 RPG in the rear of the cockpit on a flexible mount, operated manually but with hydraulic support by the bomb aimer/radio operator/navigator/observer.
The first (of three) prototypes was complete in November 1943 and made its maiden flight in April 1944. After the prototype trials, problems with flutter were encountered, a fatal flaw for an airframe subject to the stresses of dive bombing. However, the B20 showed overall very good flight characteristics and handling, despite a relatively high wing load.
Production already started in August 1944, and until the structural problems could be resolved, early production aircraft were outfitted with DB605Bs of German production (which were highly unreliable, the Swedish license production introduced over 2.000 detail changes and improvements) and two cameras in the bomb bay and used as reconnaissance aircraft, as the S20A, which took advantage of the aircraft’s high speed and long range while not over-stressing the original airframe.
Due to the lingering structural and engine troubles production of the S20A continued in small numbers and only 21 were finished. Once production of the improved SFA-built DB605B ramped up as well as the elimination of the structural problems, production switched to the improved B20B dive-bomber in March 1945, with the first operational machines, all outfitted with Swedish-built engines, arriving at frontline units in May 1945, starting with F7 Såtenäs at Lidköping.
By that time the conflict around neutral Sweden was coming to an end, and the necessity for the B20B waned. The two-engine B18, which was dive-bombing-capable, too, had become available in considerable numbers now and the production of its DB605B-powered variant (the T/B18B) had just started. Furthermore, the J21 fighter, which, despite the original intention for the type to be principally used in air defense roles, had entered service, too, but was rather utilized in the light bomber/attack role, satisfying the need for a less performant aircraft type in the Swedish arsenal, too.
B20B production was therefore already stopped after 60 only aircraft in early 1946, despite of a planned production run of 124 aircraft and the option to develop a torpedo bomber from it (a role which was taken over by the B18). Additionally, the jet age was approaching fast, and Saab began converting the piston-engine J21 to jet propulsion in 1947 as the J21R, and the even more advanced Saab 29 project was also taking shape. Both types would rather sooner than later render the B20B obsolete, and the type became only a stopgap that was operated along other types in the same units (primarily F1 and F7).
Another factor that spoke against the B20 was the obsolescence of the dive bomber concept itself. Advanced anti-aircraft defenses and potent/fast interceptors had rendered the light bomber concept from the beginning of WWII too vulnerable. In consequence the small B20B fleet was from 1947 on either modified to S20B standard (basically the same photo equipment as the early S20A machines in the reinforced B20B airframe, just with the additional option to carry two 300 l drop tanks on the underwing hardpoints to extend range; 25 airframes were converted and mostly replaced the S20As with their poor engines) or upgraded with engine modifications like water/methanol injection that raised the DB605B’s temporary maximum output to 1.700 hp (1.250 kW) and top speed in horizontal flight to almost 600 km/h (372 mph). To better cope with this extra power and as a support for the air brakes a new reversible 4 blade propeller was mounted, as well as wirings and hardpoints to carry and fire up to eight unguided rockets under the outer wings (primarily British RP-3 missiles with different war heads) or various types of 50 kg (110 lb) bombs to improve the type’s ground attack capabilities, which became the type’s new primary mission.
In its modified form the Saab 20 dive bombers. re-designated B20C, remained in service with F7 Såtenäs and F14 Halmstad in South-Eastern and -Western Sweden, respectively, alongside B18B and A21R attack aircraft. They were, however, already phased out from frontline units in 1954 with the arrival of the Saab A29B attack variant of the highly successful Tunnan fighter, and the even more potent and all-weather-capable Saab A32A Lansen. The S20Bs were also soon replaced, by jet-powered Saab S29Cs, which were much more efficient in the photo reconnaissance role.
Most Saab 20s were scrapped after their retirement, but twenty machines were saved from this fate, revamped, and handed over to Ethiopia. Furthermore, a handful Saab 20s remained in Swedish Air Force service, converted into target tugs. As B20Ds four machines soldiered on with F3 Malmslätt until 1963, when they were replaced with J29s, too.
General characteristics:
Crew: 2
Length: 10.22 m (33 ft 6 in)
Wingspan: 11.5 m (37 ft 9 in)
Height: 3.74 m (12 ft 3 in)
Wing area: 23.6 m² (254 sq ft)
Empty weight: 2,440 kg (5,379 lb)
Gross weight: 4,250 kg (9,370 lb)
Powerplant:
1× SFA DB605B V-12 inverted liquid-cooled piston engine with 1,100 kW (1,475 hp),
driving a 4-blade constant-speed, variable-pitch propeller, 11 ft 2 in (3.40 m) diameter
Performance:
Maximum speed: 595 km/h (370 mph, 323 kn)
Range: 1,465 km (910 mi, 791 nmi)
Service ceiling: 10,700 m (35,100 ft)
Rate of climb: 14 m/s (2,800 ft/min)
Wing loading: 180 kg/m² (37 lb/sq ft)
Power/mass: 0.25 kW/kg (0.15 hp/lb)
Armament:
2× forward-firing 13,2 mm (0,52 in) akan m/39A machine guns with 300 RPG
1× rearward-firing 8 mm (0.315 in) ksp m/22 machine gun with 500 rounds
Internal bomb bay for a single bomb of up to 500 kg (1,100 lb) caliber
Underwings hardpoints for either 2× 250 kg (550 lb) bombs, two 300 l drop tanks, or launch rails for
8× 50 kg (110 lb) bombs, or
8× 8 cm Pansarraket m/46C (25 lb AP Mk II RP-3 armor piercing rockets), or
8× 15 cm Sprängraket m/51 (5.9 in high explosive rockets)
The kit and its assembly:
A spontaneous build, even though I had the idea for this livery whif for some time. A while ago I had, when I looked at a Yokosuka D4Y with its liquid-cooled engine of German origin, the thought that this elegant aircraft could also have been a Swedish design, from the era when the unique Saab 21 had been designed, and a potential alternative or even successor for the rather tubby Saab 17.
It took, however, a while to turn that thought into hardware, but I eventually procured an AZ Models kit of the D4Y and built it accordingly. Initially I considered some changes, like square wing tips or a different fin, but I found the aircraft to look so conclusive (and somehow reflecting the Saab 18’s design, at least from my point of view) that I only made small cosmetical changes.
The most obvious is a different 4 blade propeller, taken wholesale from a Matchbox P-51D, just with slightly clipped blade tips. It was mounted on a metal axis and matching adapter integrated into the model’s nose section. The original small carrier tail wheel was replaced with a bigger alternative, and I added a crew to the cockpit because I did not want to present the model with an open canopy, despite the nicely detailed interior.
Another extra: the underwing ordnance. I was lucky to have a set of British unguided RP-3 missiles with 25 lb. warheads in the donor bank, which were used by the Swedish Air Force, too, and they subtly change the look of the aircraft from a dive bomber into an attack aircraft.
The AZ Models kit goes together well, has very good recessed surface details, but it has some bugs like a lack of locator pins, sprue attachment points that reach into areas that are later supposed to be glued together (requiring some extra cleaning effort), and a somewhat dubious overall fit, esp. of the wings and the fuselage – but nothing major, some PSR mends the resulting seams well.
Painting and markings:
I made a conservative choice, after I used the Saab 21 as benchmark for the B20’s operational window in history. As a post-WWII aircraft there were only two “realistic” options: bare metal, or classic olive green/blue grey. I went for the latter and added yellow squadron markings.
The Swedish “Mörkgrön” became Tamiya XF-81 (RAF Dark Green) and for the undersides’ “Blågrå” I used a Tamiya paint, too, XF-22, which has a slightly greenish tint, though. The cockpit interior was, using pictures of a contemporary Saab 18 bomber as reference, in a greenish-grey shade, mixed from Revell 67 and 75, and using the same reference the crew received suits in a pale khaki tone, looking almost like WWII USN pilots. The landing gear and the respective wells were painted with Humbrol 56 (Aluminum Dope). The spinner was painted yellow (Tamiya X-8, Lemon Yellow), close to the unit code’s tone, showing that the aircraft belonged to the 3rd squadron. The British missiles were painted in a green shade with black warheads.
The markings were puzzled together from various 1:72 sources, including roundels from an SBS Models J8 and TL Modellbau generic sheet, a PrintScale J29 sheet (tactical code) and a Moose Republic A32 decal set (F14 codes and emblem). Some graphite was used to create soot stains behind the exhaust and dirt behind the cooler outlet, and the model was sealed with matt acrlyic varnish (Italeri).
