Blackburn Bluebird IV

{{Use dmy dates|date=February 2017}} {{Use British English|date=February 2017}} {{Infobox aircraft |name = L.1C Bluebird IV |image = Blackburn Bluebird IV.jpg |caption =  |type = Tourer /Trainer |manufacturer = Blackburn Aircraft |designer =  |first_flight = 23 February 1929 |introduction = 1929 |retired = 1947 |status = |primary_user =  |more_users =  |produced = 1929–1931 |number_built = 58<ref name="Jack Black p289">Jackson 1968, p. 289.</ref> |unit cost = |developed_from = Blackburn Bluebird |variants = Blackburn B-2 }}

The '''Blackburn Bluebird IV''' was a single-engine biplane light trainer/tourer biplane with side-by-side seating designed by the British aviation manufacturer Blackburn Aircraft. It was an all-metal development of the wooden Blackburn Bluebird I, II and III aircraft.

The Blackburn IV was developed as a refinement of the preceding members of the Bluebird series; in addition to its all-metal airframe, it was noticeably more streamlined and its structure was simplified as to more readily facilitate its construction. Individual areas such as the tail unit and undercarriage were extensively revised. Conventional controls were used wherever practical. The Bluebird IV was a larger and heavier aircraft than its predecessors and could be fitted with various engines as standard, such as the de Havilland Gipsy, ADC Cirrus, and Cirrus Hermes. The first prototype performed its maiden flight on 23 February 1929. One month prior to the first flight, the prototype Bluebird IV had already been sold to a private owner that, only two weeks following, undertook a five-week long-distance journey to South Africa with it.

Due to a lack of capacity, Blackburn did not proceed with quantity manufacture of the type in-house; instead, this work was outsourced to other aviation companies. Saunders-Roe was subcontracted to construct the Bluebird IV, building 55 aircraft between late 1929 and May 1931. Another manufacturer, Boulton & Paul Ltd, was contracted to produce its wings. However, this arrangement only lasted for 15 months as Saunders-Roe was keen to pursue its own projects instead. Blackburn also established the Detroit-based company ''Blackburn Corporation of America'' with the intention to manufacture and sell both the Bluebird IV and other aircraft to customers across the whole of North America and much of South America; this venture did not achieve many sales however. Several of the privately owned Bluebird IVs undertook a number of pioneering long-distance flights, the most famous of which was the round-the-world trip by Mrs Victor Bruce. The last example of the type is believed to have been scrapped in 1947.

==Design and development== ===Background=== During 1928, Blackburn instructed their design team, headed by G. E. Petty, to conduct an extensive redesign of the wooden Bluebird trainer aircraft.<ref name="Jack Black p278">Jackson 1968, p. 278.</ref> Flight experiences with the Bluebird III had demonstrated the performance advantages of its slimmer and streamlined nose (achieved via the adoption of an ADC Cirrus III inline engine rather than a broader radial engine), and a series of wind tunnel experiments had informed the team's efforts to improve the fuselage lines. As the revised aircraft, which was referred to as the ''L.1C Bluebird IV'', took form, numerous refinements and improvements from its predecessors.<ref name="Jack Black p2789">Jackson 1968, pp. 278-279.</ref>

One substantial change, was the decision to adopt an all-metal airframe; this was designed in a manner that was also simplified considerably from its wooden predecessor so that the manufacturing process would be both easier and faster.<ref name="Jack Black p278"/> Specifically, the fuselage was divided into four subassemblies, the engine mounting, cockpit section, rear fuselage, and stern bay. Its rectangular-section basic structure comprised four equal-length longerons paired with U-shaped stringers composed of duralumin; they were fitted onto supporting stubs that enabled rapid removal for inspections and maintenance work alike. Only a single gauge of steel tubing was used throughout.<ref name="Jack Black p278"/>

The rounded rudder formerly used on the wooden Bluebirds was dispensed with in favour of a rectangular horn-balanced unit that lacked a fixed fin.<ref name="Jack Black p278"/> The tail unit, the structure of which comprised duralumin ribs and steel-tube spars, had an in-flight adjustable incidence, achieved via a notched quadrant level in the cockpit.<ref name="Jack Black p2789"/> The Frise-type ailerons were installed to the bottom wing only. A noticeable improvement in ride quality while taxing was achieved by abandoning a cross-axle undercarriage arrangement in favour of a divided counterpart that had oil-damped spiral steel springs.<ref name="Jack Black p2789"/>

The resultant Bluebird IV was both larger and heavier than its wooden predecessors. It could be fitted with a variety of engines, with the de Havilland Gipsy, ADC Cirrus, or Cirrus Hermes engines available as standard.<ref name="Jack Black p2789"/> The bench-style seating of its predecessor was replaced by a pair of individual side-by-side seats, the passenger seat was easily removable if required. Conventional stick-type flight control columns and push-pull rods were used where practical to do so, while instrumentation was clustered together on a central panel.<ref name="Jack Black p279"/> A sizable compartment for luggage is located aft of the cockpit, two glove compartments were also present in the cockpit itself. The aircraft could also be fitted with twin-floats for water-based operations.<ref name="Jack Black p279">Jackson 1968, p. 279.</ref>

===Into production=== During late 1928, amid the early stages of the first prototype's construction, the project drew the interest of Squadron Leader L. H. Slatter of the RAF High Speed Flight; he opted to purchase the aircraft a month prior to it even taking flight.<ref name="Jack Black p279"/> On 23 February 1929, the first Bluebird IV, which was powered by a Gipsy I engine, conducted its maiden flight from Brough. Few modifications were performed and even the manufacturer's trials were incomplete when Slatter made his first flight in it on 3 March; one week later, it embarked on a long distance in Slatter's hands to South Africa, performing 47 landings in mostly unprepared fields during the trip, completing the journey between Croydon and Durban on 15 April 1929.<ref name="Jack Black p27980">Jackson 1968, pp. 279-280.</ref><ref name="Jacksonv1"/>

Two additional aircraft were promptly built by Blackburn, one having an enclosed cowling for operations in Norway while the other functioned as a demonstrator.<ref name="Jack Black p280">Jackson 1968, p. 280.</ref> During April 1929, this demonstrator made its first public appearance in Croydon. As the company's own manufacturing resources were already occupied fulfilling orders for military aircraft, so further construction was subcontracted to Saunders-Roe; it would build a further 55 aircraft between late 1929 and May 1931.<ref name="Janes aviation">Taylor 1989, p. 158.</ref> Several detailed refinements were made to the structure for the purpose of speeding up construction, such as rivetting the fuselage stringers to the formers; the production line was reportedly capable of producing four aircraft per week. A separate aircraft manufacturer, Boulton & Paul Ltd, was also contracted to produce its wings at its Norwich facility.<ref>{{Harvnb|Brew|1993|p=57}}</ref><ref name="Jack Black p280"/>

However, this manufacturing arrangement only lasted for 15 months.<ref name="Jack Black p284"/> The primary reason for its termination appears to have been an emerging lack of capacity at Saunders-Roe, the company wanting to direct its resources towards a new generation of amphibians. A final batch of airframes were completed by Blackburn at Brough in response to customer orders.<ref name="Jack Black p284">Jackson 1968, p. 284.</ref>

==Operational history== thumb|A Bluebird IV, December 1929 Like the wooden Bluebirds, the Bluebird IV was heavily used by flying clubs; the side-by-side seating arrangement was considered to be particularly beneficial for instructional flying.<ref name="Jacksonv1"/><ref name="Jack Black p282">Jackson 1968, p. 282.</ref> However, it suffered from a high attrition rate. Several aircraft were reportedly lost in fatal crashes, which included a number of unexplained dives into the ground from normal cruising flight.<ref name="Jacksonv1"/> Several of the privately owned Bluebird IVs undertook a number of pioneering long-distance flights, the most famous of which was the round-the-world trip by Mrs Victor Bruce, and also included a number of flights to Australia and Africa.<ref name="Jacksonv1"/><ref name="Jack Black p2813">Jackson 1968, pp. 281-283.</ref>

Blackburn had ambitions for substantial sales of the Bluebird IV in the United States.<ref name="Jack Black p281"/> According, it established the Detroit-based company ''Blackburn Corporation of America'' with the intention to manufacture and sell both the Bluebird IV and other company aircraft to customers across the whole of North America and much of South America, with one exception being Brazil. However, a total of six Bluebird IVs would ever be ordered under this initiative.<ref name="Jack Black p281">Jackson 1968, p. 281.</ref>

Overseas operations of the Bluebird IV saw it being used for a range of purposes. One was used in Rhodesia to provide pleasure flights over the Victoria Falls during the early 1930s.<ref name="Jack Black p283">Jackson 1968, p. 283.</ref> Another aircraft reportedly performed the first purely commercial flight around Australia in a sales tour that started on 24 October 1931 and ended on 6 December of that year. A few overseas training schools also used Bluebird IVs.<ref name="Jack Black p2836">Jackson 1968, pp. 283-286.</ref>

No Bluebirds have been preserved, the last aircraft is believed to have been broken up at Hamsey Green during 1947.<ref name="Jacksonv1"/><ref name="Jack Black p287">Jackson 1968, p. 287.</ref>

==Operators== ;{{AUS}} * Royal Australian Air Force ;{{flag|Canada|1921}} * Royal Canadian Air Force ;{{flagicon|India|British}} British India ;{{UK}} * Royal Air Force

==Specifications (Bluebird IV (Gipsy I engine))== thumb|Blackburn Bluebird IV 3-view drawing from NACA Aircraft Circular No.94 {{Aircraft specs |ref= ''British Civil Aircraft since 1919, Volume 1'',<ref name="Jacksonv1">{{cite book |last = Jackson |first = A. J. |title = British Civil Aircraft since 1919, Volume 1 |year = 1974 |publisher = Putnam |location = London |isbn = 0-370-10006-9 }}</ref> ''Blackburn Aircraft since 1909''<ref name="Jack Black p2889">Jackson 1968, pp. 287-288.</ref> |prime units?= imp  |crew= 2 |length ft= 23 |length in= 2 |length note= |span ft= 30 |span in= 0 |span note= |height ft= 9 |height in= 0 |height note= |wing area sqft= 246 |wing area note= |aspect ratio= |airfoil= |empty weight lb= 1,070 |empty weight note= |gross weight lb= 1,750 |gross weight note= |max takeoff weight lb= |max takeoff weight note= |fuel capacity= |more general=  |eng1 number= 1 |eng1 name= de Havilland Gipsy I |eng1 type= four-cylinder air-cooled in-line piston engine |eng1 hp= 100 |eng1 note=

|prop blade number= 2 |prop name= fixed-pitch propeller |prop dia ft= |prop dia in= |prop dia note=  |max speed mph= 120 |max speed note= |cruise speed mph= 85 |cruise speed note= |stall speed mph= |stall speed note= |never exceed speed mph= |never exceed speed note= |range miles= 278 |range note= |ferry range miles= |ferry range note= |endurance= |ceiling ft= |ceiling note= |climb rate ftmin= 730 |climb rate note= |time to altitude= |lift to drag= |wing loading lb/sqft= 7.11 |wing loading note= |fuel consumption lb/mi= |power/mass= {{cvt|0.057|hp/lb}} |more performance= }}

==See also== {{Aircontent  |related= * Blackburn Bluebird * Blackburn B-2 |similar aircraft= * Avro Avian * de Havilland Moth |lists= |see also= }}

==References== ===Citations=== {{Reflist}}

===Bibliography=== * {{cite book |last = Brew |first = Alec |title = Boulton Paul Aircraft since 1915 |year = 1993 |location = London |publisher = Putnam Aeronautical Books |isbn = 0-85177-860-7}} * {{cite book |last = Jackson |first = A. J. |title = Blackburn Aircraft since 1909 |year = 1968 |publisher = Putnam |location = London |isbn = 0-370-00053-6 }} * {{cite book |editor-last = Taylor |editor-first = M. J. H. |title = Jane's Encyclopedia of Aviation |year = 1989 |publisher = Studio Editions |location = London |pages = 158}}

==External links== {{commons category|Blackburn Bluebird IV}} * [http://www.ivyandmartin.demon.co.uk/v_bluebird.htm The Hon Mrs Victor Bruce's Bluebird] * [https://web.archive.org/web/20070930182547/http://www.britishaircraft.co.uk/aircraftpage.php?ID=595 Blackburn Bluebird] – British Aircraft Directory

{{DEFAULTSORT:Blackburn Bluebird Iv}} Category:1920s British sport aircraft Bluebird IV Category:Single-engined tractor aircraft Category:Biplanes Category:Aircraft first flown in 1929 Category:Aircraft with fixed conventional landing gear Category:Single-engined piston aircraft