|Sk 4 - Heinkel HD 24 (1926-1939)|
Heinkel HD 24s (HD = Heinkel Doppeldecker), Sk 4 in the Air Force, was ordered in the first half of 1926 by the
MFV (the Navy aviation), just before the forming of the Swedish Air
Force. The aircraft was designed as a naval aviation trainer, but the
floats could be replaced by wheel landing gear or skis. The eight Sk 4s
were all based at the naval aviation Wing F 2 at Hägernäs.
had originally built two HD 24s for the competition
”Seeflugwettbewerb” in 1926. Further aircraft were built for the
German Airline Pilot School (DVS). The Swedish Sk 4s were ordered from
Heinkel’s Swedish subsidiary Svenska Aero AB.
the first two Sk 4s were manufactured at Heinkel’s Warnemünde works
as pattern aircraft for the rest of the series. The two aircraft were
approved by the Air Force in November 1926. Some months later, they were
given the Air Force numbers 201 and 202. The six aircraft built in
Sweden were approved in July 1927 - November 1928 (Air Force numbers
story of the engines installed at the HD 24s is somewhat complex. The
six first aircraft (201-206) were fitted with Mercedes engines of 180
hp. These engines were unfortunately not very reliable. Therefore, the
207 and 208 got Junkers Jumo L 25 engines. These engines delivered 280
hp (100 hp more than the Mercedes engines). The 207 and 208 got the
subdesignation Sk 4A. After
some time, also the 203, 204 and 206 got the L 25 engine and got their
designation changed to Sk 4A.
Aircraft 201, 202 and 205 also got their original Mercedes engines
replaced, but this time to the Armstrong Siddeley Puma (240 hp). New
designation Sk 4B.
Photo at top: The
first delivered Sk 4 with Swedish Air Force no 201 on the ice at
Airforce Wing F 2 at Hägernäs, Stockholm in early 1927.
4: Length: 9,69 m. Span: 14,20.
Height: 4,15 m.
MTOW: 2.150 kg. Max. speed: 168 km/h.
To the right the Broplan kit of Sk 4A (aircraft # 206) with
wheel landing gear fitted. Catalogue number MS-96.
Click on thumbnails for larger images.
© Lars Henriksson