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 confi ...

, 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 confi ...

with wings of rectangular plan out to blunted tips. Structurally, the largely wooden wings were based on pairs of box

spars The United States Coast Guard (USCG) Women's Reserve, also known as the SPARS (SPARS was the acronym for "Semper Paratus—Always Ready"), was the women's branch of the United States Coast Guard Reserve. It was established by the United States ...

and

spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ( taiga) regions of the Earth. ''Picea'' is the sole genus in the sub ...

and plywood

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ch ...

s, with

duralumin Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of age-hardenable aluminium alloys. The term is a combination of ''Dürener'' and ''aluminium''. Its use as a tra ...

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 aircraft t ...

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 var ...

frame. It had a

American Cirrus III The ADC Cirrus is a series of British aero engines manufactured using surplus Renault parts by the Aircraft Disposal Company (ADC) in the 1920s. The engines were air-cooled, four-cylinder inline types. They were widely used for private and li ...

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 spre ...

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 Chord may refer to: * Chord (music), an aggregate of musical pitches sounded simultaneously ** Guitar chord a chord played on a guitar, which has a particular tuning * Chord (geometry), a line segment joining two points on a curve * 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 ed ...

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 gyroplan ...

was mounted at mid-fuselage height; its

angle of incidence Angle of incidence is a measure of deviation of something from "straight on" and may refer to: * Angle of incidence (aerodynamics), angle between a wing chord and the longitudinal axis, as distinct from angle of attack In fluid dynamics, ang ...

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 a ...

. 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 Balanced rudders are used by both ships and aircraft. Both may indicate a portion of the rudder surface ahead of the hinge, placed to lower the control loads needed to turn the rudder. For aircraft the method can also be applied to elevators and ...

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. Marti ...

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 absorber A shock absorber or damper is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat) which is then dissipated. Mos ...

s within the wing root

aircraft fairing An aircraft fairing is a structure whose primary function is to produce a smooth outline and reduce drag.Crane, Dale: ''Dictionary of Aeronautical Terms, Third Edition'', page 206. Aviation Supplies & Academics Inc, Newcastle Washington, 1997. ...

s. 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 ...

Tour, which ended at

Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the wor ...

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 Gerard is a masculine forename of Proto-Germanic language, Proto-Germanic origin, variations of which exist in many Germanic and Romance languages. Like many other Germanic name, early Germanic names, it is dithematic, consisting of two meaningfu ...

, 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 from ...

, the Wright J-6-5 Whirlwind. 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 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. Incorporated ...

until it was sold in 1936 and flown to

Haiti Haiti (; ht, Ayiti ; French: ), officially the Republic of Haiti (); ) and formerly known as Hayti, is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean Sea, east of Cuba and Jamaica, and ...

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 U ...

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:

engine. 6 built. ;Emsco B-7: Wright J-6-5 Whirlwind engine. 1 converted from a B-4. ;Emsco B-7-C: Continental A70 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