Shipbucket

Splendid!

H.P.55

As the pacifism of the Western Allies was seen to have failed and rearmament became an urgent priority, in 1935 the Air Ministry issued a specification for an advanced day bomber. Looking like a Harrow fuselage with a DC-2 wing, a serial number was allocated and delivery scheduled for the prototype of 1937.



Efforts to reduce drag and improve performance were not allowed by the Ministry, although an engine change to Merlins was approved and mocked up. However due to criticisms of the design and a new desire for an aircraft able to carry a significantly greater payload, work on this design was halted.

H.P.56

In the scramble to rearm, the bomber specification of 1935 was superseded in 1936 by a specification for a significantly larger bomber, taking the technical risk of using Rolls Royce Vulture engines - then still estimating needing three years of development until ready for squadron service. In typical British style the design was to be a bomber, torpedo bomber and dive-bomber, but also capable of general reconnaissance and troop-carrying.



In 1937 HP also considered a completely unarmed highspeed version of the design. No formal design was drafted and the Ministry considered the drag calculations to be overly optimistic and rejected, but the concept was taken further by DeHavillands to create the Mosquito.
Prototypes were initially ordered with two Vulture engines, but before the end of the years this had been changed to with four Merlin engines, which meant that the original DC-2-style swept wings would have to be changed to a more straight wing with the change in weight distribution. Likewise the dive bombing, torpedo bombing and catapult launcing ability requirements were rescinded.
In this new configuration a production order was awarded in January 1938 for the design, revised to be named the H.P.57.

Hi Sheepster!

Somehow I overlooked this thread till now. Extremely informative and very well done!!

Greetings
GD

Good work!
Relationship of HP.56 with the Halifax (HP.57) can be clearly seen.

H.P.57 Halifax I

Construction was ordered in January 1937, and after the Munich Crisis production orders were massively increased. While Avro persevered with their Vulture engine Manchester, HP were able to skip directly to the Merlin - but all that meant was that the initial teething problems of a new design would continue to dog the reputation of the Halifax for all its production.



The prototype Halifax first flew in the opening days of the War, and design and production was kept as secret as possible. The first protype was flown without armorment, but the second protoype was completed fully configured. Dorsal and ventral turrets were not installed, but waist guns were installed on either fuselage side.
The first production Halifax was kept as a development aircraft, and became the most heavily armed Halifax I when testing dorsal and ventral turrets in addition to the standard gun positions.
The first operational sortie for the Halifax was on 10/11 March 1941. The secrecy of the design was such that the first Halifax casualty occurred on that first raid, and was an aircraft shot down by a British night fighter unaware of the existence of the Halifax.
Structural modifications allowed a greater all-up weight, and these aircraft were designated Halifax B.I series 2 aircraft. Initially the aircraft were fitted with retractable tailwheels, but they were troublesome and soon discarded.
The next modification involved the addition of a fuel dump system.
A Halifax B.I was the test aircraft for the H2S radar system, and was the first aircraft to fly with H2S.

H.P.58 Halifax II

With the Halifax as a night bomber, the first major modification was to create a day bomber. Armament was to include both dorsal and a ventral twin-cannon low-profile turrets, with the rear fuselage tapered as in the Hampden.



The original Halifax prototype was scheduled to be modified, and production to commence after the tenth Halifax B.I. Delays developing the turrets led to a reversion to the original Halifax tail with a new dorsal turret being planned. Eventually the delays led to the design reverting back to the original Halifax fuselage with a dorsal turret, to become the H.P.59 Halifax B.II

Fantastic work with these Sheepster! The Halifax especially has always been a favourite of mine so it's great to see you do it justice here

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Are the dorsal and ventral turrets meant to be the Boulton-Paul Type H and Type O? I'm not aware of any other 20mm cannon armed designs that would be available in 1939.

Excellent job.

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Nobody expects the Imperial Inquisition!