Thanks folks
Greg: I forgotten that you'd already done a
Hampden with a "big honking gun"! However, your "some sort of fighter' transmogrification was definitely an inspiration
------------------------
As promised for the Swedish
Hampdens (
http://beyondthesprues.com/Forum/index.php?topic=351.msg146971#msg146971 ),
Part 1 ...
Handley Page H.P.53A - the 'Swedish Hampden'In 1937, Sweden expressed interest in the Handley Page H.P.53 - a coastal patrol bomber variant of the H.P.52
Hampden which could be configured as a landplane or as twin-float seaplane. Power was to be twin 1,010 hp Bristol
Pegasus XXIV radials. It was envisioned that 70 H.P.53 would be built in Sweden for use by the
Flygvapnet. The airframes would be assembled by CVM - the government-owned air force workshops - with assistance from the
privately-owned Götaverken Flygavdelning. Engines for the H.P.53 were to be built under licence by Nohab Flygmotorfabriker AB at Trollhättan.
Initially, the H.P.53 was to be armed with the standard Swedish air-dropped torpedo - the Norwegian-designed Torped m/38 - carried semi-externally. This was a 45 cm torpedo weighing 737 kg and almost 5 metres in length. However, this requirement was eclipsed by a smaller, Bofors-designed 40 cm aerial torpedo which could be carried within the H.P.53's enclosed bomb bay. [1] This ability also prompted the
Flygvapnet technical team to recommend that the float struts could be reduced in height to lower drag. [2]
Handley Page completed the prototype H.P.53 as a landplane in late 1938. This aircraft was delivered to
Flygflottilj 2 (F 2) at Hägernäs in early January 1939. The H.P.53 was then tranferred to nearby Torslanda for conversion to floats. The completed floatplane - now designated P 5 but still wearing Swedish civil registration SE-APD - was ready for flight trials in April 1939. This aircraft was powered by 1,010 hp
Pegasus XXII engines but was otherwise to full production standards. The prototype H.P.53/P 5 was written off in a landing accident at Torslanda in late May 1939 - a portent of things to come for the 'Swedish
Hampden'.
(
Top) Handley Page-built prototype H.P.53 or P 5 (
Provflygplan), Torslanda, May 1939
Under pressure to supply
Hampdens to the RAF, Handley Page found itself unable to provide CVM with sufficient compenents or even drawings to get Swedish H.P.53 production underway. In early 1939, a potential solution presented itself. Handley Page's production line at Radlett was winding down as the RAF lost interest in the
Hereford bomber - the
Dagger-powered
Hampden derivative. [3] Some
Herefords were re-engined as
Hampdens for the RAF but the final 40 production examples were offered to Sweden in semi-completed component-knock-down form as an alternative to building the H.P.53s. This was accepted by the
Flygvapnet and the first airframe sets arrived aboard Swedish-flagged vessels in the summer of 1940.
CVM created alternative nacelles to convert the
Hereford airframes to
Hampden standard. Engine supply was more difficult. Nohab was meant to have re-started its
Pegasus production line but had been overwhelmed by the process of reverse-engineering Pratt & Whitney's
Twin Wasp. [4] Britain was unable to supply engines but a solution came from an unlikely source. The Swedish Air Attache in Rome reported that Italy was both able and willing to supply
Pegasus engines to the
Flygvapnet. As a result, Swedish-assembled
Hampdens would be powered by Alfa Romeo 128 R.C.21 radials. These were lower-powered engines - producing only 950 hk at 2,100 m - but at least they were available.
(
Bottom) British airframes, Swedish Components, Italian Engines - the CVM H.P.53A (
Flygvapnet T 5)
Bombflygplan and Torpedfällningsflygplan - the CVM H.P.53A into ServiceThe resulting CVM H.P.53A entered service with F 2 in November 1940. A handful of the type served as landplanes from Hägernäs - where it was designated by the
Flygvapnet as the B 11 reconnaissance bomber. However, the majority of H.P.53As were on floats at Torslanda as the
Flygvapnet's T 5 (for
Torpedflygplan). A detachment of T 5s also served alongside T 2s (Heinkel He 115s) from a slip at Fårösund.
Meanwhile, further ship-sets of ex-
Hereford components were arriving at Göteborg for assembly by the Götaverken Flygavdelning. However, not all was as it appeared ...
[To be continued ...]
______________________________________
[1] Bofors based its design upon the French Type 1926 DA aerial torpedo. The Bofors Torped m/40 retained the French torpedo's 40 cm (15.75-inch) diameter but shortened its length from 5.14 m to just over 4 metres. As a result, the Torped m/40 weighed only 540 kg (compared to 670 kg for the Type 1926 DA and 850 kg for the m/38). The reduced warhead size and range (due to smaller compressed air reservoirs) was judged acceptable for operations in the Baltic Sea.
[2] A downside which would later be revealed was for the H.P.53A tailplane being routinely immersed upon landing.
[3] It also helped that the first English Electric-built
Hampdens were then coming off the line at Preston.
[4] Nohab had earlier produced the lower-powered
Pegasus VIIA for the S 7A biplane. The Swedish
Twin Wasp copy would emerge as the SFA STWC-3G.