Sk 6 - Heinkel HD 36 (1927-1940)

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When the War Flying School (F 5) at Ljungbyhed was founded in 1927, general orders were issued regarding the training programme. This was to be divided into four phases:  

I - Ab-initio training.   

II - Secondary training (during heavier conditions, flying in formation and in darkness). 

III - Practice exercises and aerial reconnaissance.  

IV - Elementary naval flying. 

Due to meagre appropriations from the Parliament, the Air Staff planned to purchase one standard type of aircraft which could be used for phases I-III. This was unfortunately not a very realistic solution. On the contrary, it created big problems for a long time.  

In 1927, a Heinkel HD 36 was bought directly from Germany (HD = Heinkel Doppeldecker). The HD 36 design was a further development of the HD 35 (Sk 5), of which one single aircraft was  purchased for evaluation. The Sk 5 was found too heavy and with a too low-powered engine. The HD 36, designated Sk 6 (SwAF/n 569), was powered  with a somewhat stronger engine - the Mercedes D.IIIa,  delivering 180 hp. The Sk 6 type was intended to be the universal for the Air Force Flight Academy.   

When the single Sk 6 was bought from Heinkel in Germany, the rights for license production in Sweden were also secured. Airframes were to be manufactured at CFM - Centrala Flygverkstaden i Malmslätt (the Central Aircraft Workshop at Malmslätt), belonging to the Air Force. Earlier purchased surplus Mercedes engines of 160 hp were to power the Swedish-built aircraft. As the original HD 36 performed badly in some respects, CFM made some alterations to the design. This did not entirely cure the problems, but the aircraft was yet approved.  

20 aircraft were built by CFM in two batches of ten aircraft each. They were delivered to F 5 in 1929 and in 1930. But the engines caused problems from the beginning. The engines, all with long running times, were unreliable. In the beginning of 1931, longer flights were forbidden. In less than a month, eleven force landings had been made due to engine troubles.     

To solve the problem, the engines were replaced. Armstrong Siddeley Puma engines of 240 hp were installed in all aircraft. The designation of the aircraft was changed to Sk 6A. The Puma engines were unused, but as they were bought as surplus, they were far from new. A thing that soon showed itself. The Sk 6A was never used for basic (type I) training. Most of them were disassembled and stored after a couple of years. Before that, they were used mostly used for the training of observers.   

Photo at top: Sk 6, SwAF/n 569 (marked "41") with skis.

Photo: below: Sk 6A, SwAF/n 575, at Malmslätt. Both photos via Lars E. Lundin, Västervik.

Sk 6A: Length: 7,50 m. Span:10,97 m. MTOW 1.250 kg. Max. speed: 130 km/h.


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© Lars Henriksson

Updated 2010-07-10