Avia S.91; aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force, 1950

Dizzyfugu · February 06, 2014, 01:55:10 AM

More or less a double post with the Anthony P Memorial GB entry, but now/here in a compact article:

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

Some background:
During the Second World War, the Slovak Air force was charged with the defense of Slovak airspace, and, after the invasion of Russia, provided air cover for Slovak forces fighting against the Soviet Union on the Eastern Front While engaged on the Eastern Front, Slovakia's obsolete biplanes were replaced with German combat aircraft, including the Messerschmitt Bf 109 and the Focke Wulf Fw 190. The air force was sent back to Slovakia after combat fatigue and desertion had reduced the pilots' effectiveness. Slovak air units took part in the Slovak National Uprising against Germany from late August 1944.

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

Towards the end of the war, General Alois Vicherek left Britain for the Soviet Union, where he was supposed to take over command of the Czechoslovak Air Force in the USSR. However he only arrived on May 1, 1945, when the war was almost over. Vicherek was happy to serve an Eastern Bloc Czechoslovakia, and on May 29, 1945, he was appointed the Commander of the Czechoslovak Air Force.

Initial equipment of the Czechoslovak Air Force directly after WWII consisted mainly of surviving German aircraft, and parts and tools in the factory sites on Czechoslovak territory. One of these "indigenous" types were the Avia S-99 (a Bf 109G-6) and the S-199, a Bf 109 derivate with a Junkers Jumo 211 F engine that actually belonged to the He 111 bomber. Another similar family consisted of the Avia S-90 and S-91: the S-90 was a Fw 190 A-8, while the S-91 was built from unfinished Fw 190 A-8 airframes and spare parts, and due to the lack of engines outfitted with a Soviet Shvetsov ASh-82FNU engine and other Soviet equipment.

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

All these aircraft were built or made airworthy by the two aircraft factories in Czechoslovakia: one of them officially called závod Avia (Avia Plant) (1946–48) and závod Avia-Jiřího Dimitrova (Avia-George Dimitroff-Plant, 1948–49) in Čakovice near Prague, as a post-war corporative part of the Automobilové závody, n.p. [Automotive Works, National Corp.], and the other one called závod Vysočany (Vysočany Plant, 1948–49) in Prague, as a corporative part of Letecké závody, n.p. [Aviation Works, National Corp.] They were effectively constructed with parts and plans left over from Luftwaffe aircraft production that had taken place under the country's German occupation during the war.

While around 550 S-199s were built and even exported to Israel, the S-90 and S-91 were only produced in small numbers, and only for the Czechoslovak Air Force. About 40 S-90 were taken into service in 1946, while the assembly of the S-91 with its different engine and other adaptations started in 1948, and less than 20 were built from existing materials – none was actually newly manufactured.

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

The S-91 was easy to recognize by its bigger fin with a square outline, as well as the different cowling with its oil cooler underneath the ASh-82FNU. This was an improved M-82FN with more boost pressure and RPM and the power output increased to 1,380 kW (1,850 hp). The different engine and its radiator fan called for a different spinner, too, so that the nose profile differed considerably from the Fw 190 A-8, even though most of the internal structure was still the same.

Armament of the S-91 consisted of four Nudelman-Suranov NS-23 23 mm cannons in the wings (one pair in the wing roots, synchronized to fire through the propeller disc, and another pair outside of the landing gear wells) with 125 RPG, the fuselage-mounted machine guns of the Fw 190 A-8 were omitted to save weight. The original underfuselage hardpoint for a drop tank or a bomb of up to 500 kg (1.102 lb) caliber was retained, as well as optional hardpoints under the wings for bombs or other ordnance of up to 250 kg (551 lb) weight, even though the S-90 and S-91 were almost exclusively used in the fighter role. Both types were very popular among the crews, as they were both much more agile and better armed than the rather sluggish S-199, which was cheaper to produce, though.

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

The S-90's and S-91's service career was short, though: from 1955 Czechoslovakia became a member of the Warsaw Pact. Because of this, the Czechoslovak Air Force started to use Soviet aircraft, doctrines, and tactics, and with the purchase of equipment of Soviet origin the leftover WWII relics were soon retired. Nevertheless, both received the NATO ASCC reporting names 'Finch A & B', respectively. The S-90 was phased out until 1958, the slightly superior S-91 followed soon in 1960, when both were replaced by MiG-15 jet fighters.

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

General characteristics
Crew: 1
Length: 9.10 m (29 ft 7 in)
Wingspan: 10.51 m (34 ft 5 in)
Height: 3.95 m (12 ft 12 in)
Wing area: 18.30 m² (196.99 ft²)
Empty weight: 3.170 kg (7.010 lb)
Loaded weight: 4.400 kg (9.700 lb)
Max. takeoff weight: 4,900 kg (10,800 lb)

Powerplant
1× Shvetsov ASh-82FNU air-cooled radial engine with a two-stage supercharger and fuel injection, rated at 1,380 kW (1,850 hp)

Performance
Maximum speed: 685 km/h (426 mph) at 6,600 m (21,655 ft), 710 km/h (440 mph) at 37,000 ft (11,000 m)
Range: 950 km (590 mi), clean and with internal fuel only
Service ceiling: 12,000 m (39,370 ft)
Rate of climb: 758 m/min (2,487 ft/min)
Wing loading: 241 kg/m² (49.4 lb/ft²)
Power/mass: 0.29-0.33 kW/kg (0.18-0.21 hp/lb)

Armament
4× Nudelman-Suranov NS-23 23 mm cannons with 125 RPG in the wings
Up to 1.000kg (2.202 lb) of external ordnance on three hardpoints under the fuselage and under the outer wings (rarely used)

The kit and its assembly:
Another whif inspired by someone else's idea. This time, the model was inspired by Czech-based fellow user PantherG at whatifmodelers.com, who posted a profile of a Fw 190 A-8 in Czechoslovak Air Force markings, the Avia S-90 - the latter must have been an authentic designation, but I could not find any proof for a service use of the Fw 190 A-8 in the Czechoslovak Air Force?

Anyway, the post-WWII idea had its charm, and I liked PantherG's idea of a rather ugly livery in RLM colors. So much that I decided to build it in hardware form! But, as things evolved, I decided to add a personal twist to the model, taking the original idea one step further.

This led directly to "my" S-91: a re-engined variant of the S-90 – I found parts for a Shvetsov ASh-82 engine in my scrap box, and thought THAT could be a fine alternative...?

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) - WiP by dizzyfugu, on Flickr

The basic kit is the Academy Fw-190 A-8, a solid model with some flaws (e .g. a rather clumsy landing gear), but with good fit and overall details. It is mostly built OOB, with only minor mods: The engine cowling was re-shaped with putty, two ram air scoops for the twin turbochargers were added and a chin oil cooler was mounted added. A new propeller with the typical, different radiator fan was scratched from various single parts (I assume there are He 100D, Spitfire and I-210 parts in it!).

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) - WiP by dizzyfugu, on Flickr

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) - WiP by dizzyfugu, on Flickr

As an additional design twist the Fw 190 fin was replaced by a leftover Me 163 donation part, making it taller and slightly larger in area. This change was not really necessary, but I wanted to change the Fw 190's classic outline a little, for a more modern and Lavochkin La-9/11-like look.
Unfortunately the model suffered from a major crash from the work bench, just before I wanted to apply decals - the fin was ripped apart. I tried to fix it, but the damage can still be recognized.

The fuselage hardpoint comes from a Hobby Boss Fw 190, but it was left empty. In the cockpit a different seat was added, as well as a Matchbox pilot figure and a scratched gun sight. Hollow steel needles were used as gun barrels on the wings.

Painting and markings
As already mentioned, I liked the rather ugly choice of camouflage that PantherG suggested for his S-90: RLM 75 & 81 (Grauviolett & Braunviolett, yuck!) from above and RLM 76 for the lower sides. Despite the kit mods I decided to stick to PantherG's original design as much as possible - I just changed the aircraft's squadron, since I found appropriate emblems in the stash (see below). Another motivation was that I wanted to see how sick this would actually look like on a Fw 190...

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) - WiP by dizzyfugu, on Flickr

I used ModelMaster Authentic enamels for the upper surfaces authentic RLM tones (2085 & 2090), and I tried the new RLM 76 from Humbrol (#247) for the lower sides.

Comparison of various RLM 76 enamel paint options by dizzyfugu, on Flickr

Compared with the Modelmaster enamel, Humbrol 247 is slightly lighter and recognizably more turquise, almost like RLM 65, and close to Humbrol 128 (FS 36320). In contrast to the poor RLM 83 (Humbrol 253) which I recently used and which failed miserably, the RLM 76 paint is fine: Opaque, good to apply with a synthetic brush, dries up quickly and with an even, matt finish. I hope the horrible 253 enamel is/was just a one-off!

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) - WiP by dizzyfugu, on Flickr

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) - WiP by dizzyfugu, on Flickr

After basic painting, the kit received a black ink wash and some dry painting on panels for weathering and visual drama (with Humbrol 155, 140 and 127), as well as some very light dry-brushed silver on leading edges – the aircraft was supposed to look used, but not too worn. Exhaust an soot stains were also added, with grinded graphite.

All interior surfaces were painted in Extra Dark Slate Grey, as a dull alternative to RLM02.

The markings were puzzled together, according to the original profile sketch; the Czechoslovakian roundels come from KP Arado Ar 96 and Yak-23 kits. Unfortunately I did not have roundels with white outlines in appropriate size in store, but the blue alternative does not look bad at all.
The tactical code was made from single letters from TL Modellbau. The unit badge, a black bat on yellow ground (a full moon?), comes from the Bilek MiG-21PF kit. The few other stencils etc. were taken from the OOB sheet of the Academy Fw 190 kit.

1:72 Avia S.91 (NATO Code 'Finch B'); aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force (Československé vojenské letectvo); Letňany AB, summer 1950 (Whif/Academy kit conversion) by dizzyfugu, on Flickr

So, a double tribute: first of all to Czech fellow modeler PantherG (who also inspired my German Marineflieger Super Étendard last year), and it is also a suitable contribution to a recent Group Build in memoriam of a deceased fellow user at whatifmodelers.com.

PantherG · February 06, 2014, 02:30:58 AM

Very nice build and AMAZING story about...

About service of S-90 (Focke Wulf Fw-190 A-8) in Czchoslovak Air Force in "true reality"....
After WW II was planned,that Fw-190 A-8 will be one of backbone types of CzAF. From many causes like a basic type was chosen Bf-109 G/K (S-99/S-199).
In service was only one or two of Fw-190 for testing. Today is not exactly known,if this was A-8 or F-8.

Dizzyfugu · February 06, 2014, 02:40:53 AM

Ah, that's a great info - I found in an old GDR-published book the hint that S-90 was the treu/official designation for the Fw 190 A/F-8 in CzAF service, but was not able to find any further clues concerning real service duty!

Glad you like it!

springheel jack · February 06, 2014, 06:53:15 AM

That's a nice model . You certainly have the knack of taking photos of your models

Dizzyfugu · February 06, 2014, 06:59:56 AM

Thank you. It's just practice - there's no rocket science behind the pics! But they add a lot of realism and improve overall impression: perspective is one key, and also the surrounding scene. All pics are also "taken as they are", with a simple pocket camera, and it's no composing. I just edit away a holder, if it's a flight scene, but do not change the pic as such.

Avia S.91; aircraft 'IF-07' of 2. Letka, 1. SLP, Czechoslovak Air Force, 1950

Dizzyfugu

PantherG

Dizzyfugu

springheel jack

Dizzyfugu