Blackburn - pre-WW2 commercial flying boat projects

[Schneiderman]

Civil variants of the large Iris flying boat had failed to attract any orders, but with a contract secured to build the R.B.2 Sydney 3-engine reconnaissance flying boat for the Air Ministry Blackburn pushed ahead with the design and construction of a civil commercial derivative, the C.B.2E Nile for their airline venture in association with Alan Cobham. As noted in previous thread this was abandoned when Air Ministry approval and subsidies were not forthcoming. The project is well known and discussed elsewhere on this forum but is repeated here as it is the starting point for a small family or commercial flying boats of similar style. A version with sponsons in place of the usual wing floats was considered.

 

[Schneiderman]

C.B.5 Oceanic

The first project developed from the Nile was the C.B.5 Oceanic dating from February 1929. This 6-engine flying boat had a cabin capable of accommodating up to 50 passengers. The engines were specified as Rolls-Royce ‘H’ (later renamed as the Buzzard), two as tractors in the outer nacelles and four as tandem tractor and pusher pairs in the inner nacelles. Maximum range with 50 passengers and cargo limited to 1000lb was 1000 miles. The Blackburn brochure pre-dates the official issue of Air Ministry specification 20/28 for a civil flying boat but matches the requirements. It also pre-dates the Supermarine Type 179 project that was ordered to meet the specification. Whether the Oceanic was designed to meet an early draft of the specification or influenced the writing of the specification is not known.



Although Supermarine were contracted to build the Type 179 Blackburn did not abandon their project but reworked the concept, publishing details in 1931. The changes were not great, the more obvious being the installation of all the engines as tractors and the addition of a control cabin on the leading edge of the wing centre section. Maximum range, loaded as above, had increased to 2500 miles.

 

[Schneiderman]

L4

In October 1929 Blackburn responded to a specification issued by Imperial Airways for a four engine flying boat, the specification that was fulfilled by the Short Kent. Blackburn’s submission was the L4, a monoplane powered by four Armstrong-Siddeley Leopard J with accommodation for 21 passengers and a range of just 450 miles. The drawings are missing from the brochure I have viewed but the dimensions and description make it obvious that the layout was like a scaled-down Oceanic or scaled-up Nile.



At the end of the brochure there is a brief table that compares the L4 with two smaller versions. The J4, was a 14 passenger aircraft powered by four Bristol Jupiter X or Armstrong- Siddeley Jaguars and the J3, 8 passengers with three Jupiters or Jaguars.

 

[Schneiderman]

No known designation no.1

In 1933 Blackburn issued a brochure for a completely new design. The 4-engine Merchant Flying Boat was a long range biplane designed for routes such as the transatlantic route of up to 2000 miles carrying up to 8 passengers with stops at Newfoundland for the northerly option or the Azores for the southerly. It was to be powered by Junkers Jumo IV diesel engines (Napier Culverin). Two different wing designs and engine installations were considered.





Work undertaken at the RAE and patent applications by Blackburn could appear to suggest that a design broadly along these lines, rather than one similar to the L4/J4 projects as I suggested, tentatively, in a thread a few years ago, may have been submitted as Blackburn’s tender to Specification 3/33 for a large reconnaissance flying boat, which resulted in the Short Sunderland.

 

[Schneiderman]

No known designation no.2

In 1934 John Rennie conceived the idea of a flying boat where the planing bottom was retractable, thereby reducing the front cross section area of the aircraft, and hence profile drag, when in the air. The concept was the subject of a patent application in 1935 and wind tunnel and tank studies undertaken by the RAE in the same year. The initial twin-engine design, the B.B.3, formed the basis for a number of subsequent projects.




An un-named 4-engined Civil Flying Boat was described in a specification brochure issued in September 1935. It was to be powered by four Bristol Aquila radials, the smallest of Bristol’s new family of sleeve-valve engines. The aircraft, although moderately large, was only configured to carry up to 8 passengers. Range was up to 1200 miles. It is hard to envisage how this would have been commercially viable.
A military version of the aircraft was tendered to meet Specification R.12/35 for a high performance reconnaissance flying boat. This had a maximum range of 2000 miles.

 

[Schneiderman]

B.B.4

Also in September 1935 Blackburn drew up the B.B.4, a 32 passenger flying boat powered by four Bristol Taurus TE-1M twin-row radials. The lines were essentially a scaled-up version of the previous project but lacked the retractable planing bottom. Range is not known.