The Emsco B-4 Cirrus was a

mid-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

, two-seat trainer built in the US in the late 1920s. Six were built and three variants with more powerful engines flown.

Design

The two-seat B-4 trainer was a mid-wing

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

with wings of rectangular plan out to blunted tips. Structurally, the largely wooden wings were based on pairs of box spars and spruce and plywood ribs, with duralumin sheet stiffening the

leading edge The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...

s. The rest of the wing was fabric covered. They were wire-braced from above and below with streamlined wires from pylons within the

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraf ...

to the spars. Its Frise ailerons were inset. The B-4's fuselage was based on a

chrome-molybdenum steel 41xx steel is a family of SAE steel grades, as specified by the Society of Automotive Engineers (SAE). Alloying elements include chromium and molybdenum, and as a result these materials are often informally referred to as chromoly steel (common ...

frame. It had a American Cirrus III four-cylinder, upright inline engine in the nose with an aluminium

firewall Firewall may refer to: * Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts * Firewall (construction), a barrier inside a building, designed to limit the spr ...

and tanks in the wing roots. The two

tandem Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction. The original use of the term in English was in ''tandem harness'', which is used for two ...

cockpits, fitted with dual controls, were over the wing. The view from the forward cockpit, placed around quarter- chord, was good and the instructor's view from the rear cockpit was improved with windows in the underside wing roots. The B-4's

empennage The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow.Crane, Dale: ''Dictionary of Aeronautical Terms, third e ...

was conventional, framed like the wings and fabric covered. The

tailplane A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyropla ...

was mounted at mid-fuselage height; its angle of incidence could be varied in-flight for trimming. It carried split, unbalanced

elevators An elevator or lift is a cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or decks of a building, vessel, or other structure. They are ...

. There was a small

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...

with a curved-topped, straight-edged balanced rudder which extended down to the keel between the elevators. It had conventional, split axle, fixed

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

with a track. The axles and drag struts were hinged from the same pylon used by the lower wing bracing wires.

Strut A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension. Human anatomy Part of the functionality o ...

s joined the wheels, enclosed in fairings, to shock absorbers within the wing root aircraft fairings. At the rear the B-4 had a tripod tailskid with a vertical rubber shock absorbing extension of the rudder post.

Development

The exact date of the first flight of the Emsco Cirrus is not known, though it was flying in mid-November 1929. It was one of the aircraft taking part in the non-competitive First All-

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

Tour, which ended at

Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the List of municipalities in California, largest city in the U.S. state, state of California and the List of United States cities by population, sec ...

on 7 November. This event was intended to advertise the Western Aircraft Show held at Los Angeles from 9–17 November, where the Cirrus was on display. Its tests were complete by January 1930, though it never reached certification, partly because of the departure of its designer, Charles Rocheville, from the firm. His replacement Gerard Vultee, ex-Lockheed, decided to re-engine the sole B-4 with a five-cylinder

radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective form of * Radial distance, a directional coordinate in a polar coordinate system * Radial set * A bearing f ...

, the

Wright J-6-5 Whirlwind The Wright R-540 Whirlwind was a series of five-cylinder air-cooled radial aircraft engines built by the Wright Aeronautical division of Curtiss-Wright. These engines had a displacement of 540 in³ (8.85 L) and power ratings of around ...

. The modified aircraft was designated B-7 and received its Approved Type Rating (ATC) on 21 February 1931. It was longer than the B-4 and was about heavier empty. No other B-7s were built; instead it was followed by the newly built, solitary B-7-C, powered by a Continental A.70 seven-cylinder radial which produced the same power as the Whirlwind. It was longer than the B-4 but was otherwise similar to the B-7, with about the same empty weight, though it had various refinements such as a tailwheel. The B-7-C got its ATC in June 1931. Vultee left Emsco to set up

Vultee Aircraft The Vultee Aircraft Corporation became an independent company in 1939 in Los Angeles County, California. It had limited success before merging with the Consolidated Aircraft Corporation in 1943, to form the Consolidated Vultee Aircraft Corporatio ...

and was replaced by T.V. van Stone, who built another airframe with a

Curtiss Challenger The Curtiss R-600 Challenger was a six-cylinder, double-row, air-cooled, radial engine for aircraft use built in the United States in the late 1920s. It developed . Design and development Curtiss started work on a small six-cylinder engine in Ma ...

six-cylinder radial. Designated B-7-CH, it flew late in 1931.

Operational history

Little is known about the six B-4s constructed apart from the B-7 conversion. The latter's subsequent career is also obscure. The B-7-C was scrapped in 1946 but its flying life is not recorded. The B-7-CH has a better recorded history. It was used for a time by Scott Flying Services of

Long Beach Long Beach is a city in Los Angeles County, California. It is the 42nd-most populous city in the United States, with a population of 466,742 as of 2020. A charter city, Long Beach is the seventh-most populous city in California. Incorporate ...

until it was sold in 1936 and flown to Haiti with the intention of starting an internal service there. It returned to

New York City New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...

where a new owner took it back to the West Coast and sold it on. It was last recorded at the Multnomah School of Aviation in 1950.

Variants

;Emsco B-4 Cirrus: American Cirrus III engine. 6 built. ;Emsco B-7:

engine. 1 converted from a B-4. ;Emsco B-7-C:

Continental A70 Continental may refer to: Places * Continent, the major landmasses of Earth * Continental, Arizona, a small community in Pima County, Arizona, US * Continental, Ohio, a small town in Putnam County, US Arts and entertainment * ''Continental'' (a ...

engine. 1 built. ;Emsco B-7-CH:

engine. 1 built.

Specifications (B-4 Cirrus)

References

{{Emsco aircraft 1920s United States sport aircraft Mid-wing aircraft Single-engined tractor aircraft Aircraft first flown in 1929