+++ DISCLAIMER +++
Nothing you see here is real, even though the model, the conversion or the presented background story might be based historical facts. BEWARE!
Some background:
The Heinkel He 70 Blitz (Lightning) was designed in the early 1930s to serve as a mailplane for Deutsche Luft Hansa in response to a request for an aircraft faster than the Lockheed Vega and Orion (as used by Swissair) for use on short routes.
It was a low-wing monoplane, with the main characteristic of its design being its elliptical wing (which the Günther brothers had already used for the Bäumer Sausewind sports aircraft before they joined Heinkel) and its small, rounded control surfaces. In order to meet the demanding speed requirements, the design minimized drag with a steamlined cowling, flush rivets, giving a smooth surface finish, and a retractable undercarriage. It was powered by a liquid-cooled BMW VI V12, cooled by ethylene glycol rather than water, allowing a smaller radiator and therefore reducing drag even further. The pilot and radio operator were seated in tandem, with a cabin housing four passengers on two double seats facing each other behind them.
The first prototype flew on 1 December 1932, and proved to have excellent performance, setting eight world records for speed over distance, and reaching a maximum speed of 377 km/h (222 mph) – faster than many contemporary fighter aircraft.
Luft Hansa operated He 70s between 1934 and 1937 for a fast flight service, which connected Berlin with Frankfurt, Hamburg and Cologne, as well as on the Cologne/Hamburg route. He 70s were also flown abroad from Stuttgart to Seville between 1934 and 1936. This route was part of the South America mail service provided by Luft Hansa that continued via Bathurst, The Gambia to Natal, Brazil, using Junkers Ju 52/3m and Dornier Wal flying boats. Swissair received a few Heinkel He 70s for express trans-alpine flights between Zurich and Milan in 1934, too.
Remaining aircraft were transferred to the Luftwaffe in 1937, and the type saw limited military use during WWII. The Luftwaffe operated He 70s from 1935 onwards, initially as a light bomber and reconnaissance aircraft, but as soon as purpose-built designs became available, the He 70 was relegated to liaison and courier aircraft duties.
Twenty-eight He 70s were sent with the Legion Condor and used during the Spanish Civil War as fast reconnaissance aircraft. Their high speed (and likely the already existing "blitz" title) gave them the nickname Rayo (lightning).
The He 70K was another fast reconnaissance airplane variant, but it was powered by a WM-K-14 radial engine, a license-built version of the French Gnome-Rhône 14K Mistral Major engine. It was used by the Royal Hungarian Air Force in early World War II during 1941–42 and later re-designated He 170 (since the suffix “K” originally indicated “kommerziell” for a civil export version).
Another military customer of the He70K was Sweden, even though in the unique form of a floatplane conversion. Twelve machines, basically of similar configuration to the land-based Hungarian He 70Ks, were delivered in 1937 and operated for reconnaissance and patrol duties along the Baltic coast line under the local designation S 13 (Spaning = Observation). By the end of the hostilities in Europe in 1945, nine S 13 floatplanes were still operational but deemed outdated for military purposes.
However, six of the robust machines were still in good shape and earmarked for the new Scandinavian Airlines System (better known as 'SAS'). SAS airline was officially founded on 1 August 1946, when Svensk Interkontinental Lufttrafik AB (an airline owned by the Swedish Wallenberg family), Det Danske Luftfartselskab A/S and Det Norske Luftfartselskap AS (the flag carriers of Denmark and Norway) formed a partnership to handle the intercontinental air traffic of these three Scandinavian countries. Operations started on 17 September 1946, and the revamped He 70 floatplanes (registered in Norway with the codes LN-KMA-F) were to operate in the northern regions of Norway and Sweden for postal and other transport services, extending the Hurtigruten postal ship connections landwards. The other three surviving aircraft were retired, but stored for spares.
All military equipment, like the dorsal defensive weapon station, which was simply faired over, was deleted. The civilian crew consisted typically of two (pilot and navigator/Radio operator), but a PostVerket (the Swedish Postal service) official who would assist loading and handle the official paperwork was a frequent third crew member.
For easier loading the machines received bigger two-wing freight room doors on both sides of the fuselage, and the original Gnome-Rhône 14K engine with 746 kW (1,000 hp) was replaced by its post-war SNECMA 14R evolution. This supercharged engine considerably improved the aircraft’s take-off performance and overall payload (400kg of goods could be carried now instead of 300kg) and temporarily delivered 1,190 kW (1,590 hp). The cabin had a level floor and featured foldable seats on the side walls for up to six passengers, even though this was only a secondary duty.
In 1948 the Swedish flag carrier AB Aerotransport joined SAS and the companies coordinated European operations and finally merged to form the SAS Consortium in 1951. When established, the airline was divided between SAS Danmark (28.6%), SAS Norge (28.6%) and SAS Sverige (42.8%), all owned 50% by private investors and 50% by their governments.
However, the fast technical development in the late Forties and the advent of the jet age rendered the SAS’ He 70 floatplane fleet quickly obsolete and they were retired in 1953.
General characteristics:
Crew: 2 (pilot, navigator/radio operator) plus up to 6 passengers
Length: 11.70 m (38 ft 4⅔ in)
Wingspan: 14.80 m (48 ft 6⅔.75 in)
Height: 3.10 m (10 ft 2 in)
Wing area: 36.50 m² (392.9 sq ft)
Empty weight: 2,360 kg (5,203 lb)
Loaded weight: 3,386 kg (7,450 lb)
Max. takeoff weight: 3,500 kg (7,700 lb)
Powerplant:
1× SNECMA 14R supercharged 14 cylinder radial engine with 1,190 kW (1,590 hp) for take-off
Performance:
Maximum speed: 320 km/h (177 knots, 200 mph) at sea level
Cruise speed: 260 km/h (144 knots, 162 mph)
Range: 2,100 km (1,135 nmi, 1,305 mi)
Service ceiling: 5,300 m (17,390 ft)
Climb to 1,000 m (3,300 ft) 3 min
Climb to 4,000 m (13,125 ft): 18 min
The kit and its assembly:
A straightforward idea for the “Flying Boat, Seaplane and Amphibian” Group Build at whatifmodelers.com in late 2017. This civilian transport aircraft originally started as a military aircraft (even though this one might materialize later, too). The decision to change the topic fell when I came across a Ju 52/3m sheet (Italeri) in my decal box which features an SAS machine. After some legwork I found that these machines were still in use in the Fifties, and so, why not add a smaller aircraft on floats to the post-WWII SAS fleet for remote regions, e. g. for postal service? The He 70 appeared like a plausible candidate, and from this concept the model evolved.
Kit basis is the Matchbox He 70, and the floats come from the KP Letov S.328, a popular donor source since you find this kit quite often and with a small price tag. The floats are still a little ‘petites’ for the He 70, and their "track" is rather narrow. But the combo works, since the He 70 is a very sleek aircraft.
The floats’ assembly needed some serious PSR, though, and mounting them to the wobbly struts was challenging in itself. They were outfitted with mooring anchors, new rudders (one OOB piece got lost, they are very fragile and wobbly) and walking planks.
The aircraft model is a Revell re-boxing of the Matchbox He 70, and the kit is a PITA. Gone are the days when I thought that a Matchbox kit was simple, but would go together well. Here, nothing really fits, PSR everywhere, this thing SUCKS. Be warned!
Since the small windows do not allow much view inside, the interior was kept at a minimum detail level. The original IP side windows were omitted, because they are thick and blurry, and they were later replaced/filled with ClearFix. The cockpit canopy is OOB, but it is so small (and thick, too) that only the pilot's head can be seen – or better: guessed. Since there’s surprisingly little space under the canopy, I could not mount an 1:72 figure and rather used a generic 1:87 (H0 scale) sitting figure.
The machine was built with the radial engine option (IMHO a plausible option for the original military operator and also more suitable for operations in the Far North), but the primitive OOB "engine plate" was replaced by a deeper and much better detailed resin piece found in the scrap box (IIRC, left over from a converted ArtModel Polikarpov I-185). It fits snuggly into the OOB front end, even though the ring cover needed some tuning. The propeller is new, too (from a Hobby Boss Fw 190A/F, IIRC), mated with a new axis.
In order to adapt the He 70 to the new floats the original landing gear openings were closed (thankfully, the kit comes with dedicated covers) and blended into the lower wing surface with putty. In order to give the floats a good hold to the fuselage, small round adapters (actually rings cut from a 3mm styrene tube) were glued to the lower hull. Not the most elegant solution, but a pragmatic way to bridge some gaps and lay a good foundation.
In order to add stability to the aircraft with the additional draggy floats, I mounted a ventral fin under the rear fuselage, under the fin.
Another detail: due to the floats, the crew and potential passengers would need boarding ladders, and I used the He 115 as a benchmark. I knew that I have some PE ladders somewhere, but could not find them... So I had to improvise and converted IP window frames from a H0 scale American industrial building into boarding aids. Looks better than most OOB solutions!
Towards the finish line, a HO scale pilot figure added to the cockpit (it's tight and the canopy so thick that I could not fit an 1:72 pilot inside!) and the canopy stuck into place with white glue.
Painting and markings:
I kept this aspect very simple, and used the livery of a post-WW2 Ju 52/3m as benchmark: uniform silver, but apparently not in NMF – but this could also be corroded aluminum. Or is it a silver paint coat against corrosion? The only contrast were black engine covers, and the airline markings.
In order to achieve the silver paint look I tried an experiment: a basic overall coat with acrylic paint from a rattle can, a Duplicolor tone called "Weissaluminium" - which, on the reference sample, rather looks like a greyish paint than a true NMF; at first I was skeptical about the mica particles' size when the paint was still fresh, but once dry the coat looked very good and even, and more like a bare NMF than expected. On top of that, some panel shading with Polished Aluminum Metallizer was added, but only lightly.
In order to add some more "color" I decided to paint the underwater parts of the floats in black. Not a good idea – at least with the Tamiya tape I used for a clean demarcation line... Painting went fine, but when I removed the tape wide sections of the alu paint came off with them. Hmpf.
Anyway, I will try to use the damage creatively and not sand it off or overpaint the damage with silver - I'll rather use a grey primer, as if some real world damage would have been repaired. After all, it's a kind of bush aircraft.
Then the black cowling was added, and I started with the decals, which had to be improvised. For the civil registration code on the wings I used large USAF 45° characters (from a Colorado Decals sheet) – chosing those letters which do not show the typical font, rather simple forms.
For the fuselage markings I used leftover material from an 1:144 SAS Caravelle from Mistercraft. These are a little modern for the aircraft’s intended timeframe, but the characteristic blue cheatline with the dragon boat head at the nose was already present on early post-war SAS aircraft, so this detail is more or less O.K., and with the trim in place the aircraft looks very elegant. The “Scandinavian” line also comes from the Caravelle – it should be complemented by “Airlines System” in smaller front, but this was not available, and the line alone was already so big and long that it covers literally the whole cabin.
However, the problem with these decals was that the cheatlines featured the triangular Caravelle windows, so that I had to paint them over manually (with Humbrol 104, which is a good match, though). Some more decals, like the country emblems on the fuselage, come from an Italeri SAS Ju 52/3m, or the OOB sheet. The cabin doors were simulated with single 0.5mm decal strips in black.
Finally the kit was sealed with semi-matt acrylic varnish (Italeri), the windows were created with Humbrol ClearFix (instead of the OOB styrene pieces) and almost no other weathering was done. In a final step, the floats were mounted under the fuselage and a wire antenna added.
Not a spectacular whif, but an elegant one, despite (or thanks to?) the relatively simple civil scheme. The Letov S.328 floats are IMHO a good match in size and volume, but somehow I think the floats’ track with is a little too narrow? Anyway, I stuck with it, and the resulting He 70 floatplane does not look bad at all.
