Lycoming O-340

Last updated
O-340
Type Piston aero-engine
National origin United States
Manufacturer Lycoming Engines
First run1953
Major applications Temco D-16 [1]
Brantly B-2 [1]
Produced1954–1957 out of production
Developed from Lycoming O-320

The Lycoming O-340 is a family of four-cylinder horizontally opposed, carburetor-equipped aircraft engines, that was manufactured by Lycoming Engines in the mid-1950s. [2]

Flat engine engine configuration with horizontally opposed cylinders

A flat engine is an internal combustion engine with horizontally-opposed cylinders. Typically, the layout has cylinders arranged in two banks on either side of a single crankshaft and is otherwise known as the boxer, or horizontally-opposed engine. The concept was patented in 1896 by engineer Karl Benz, who called it the "contra engine."

Carburetor device that mixes air and fuel for internal combustion engines

A carburetor or carburettor is a device that mixes air and fuel for internal combustion engines in the proper air–fuel ratio for combustion. It is sometimes colloquially shortened to carb in the UK and North America or carby in Australia. To carburate or carburet means to mix the air and fuel or to equip with a carburetor for that purpose.

Lycoming Engines is a major American manufacturer of aircraft engines. With a factory in Williamsport, Pennsylvania, Lycoming produces a line of horizontally opposed, air-cooled, four-, six- and eight-cylinder engines including the only FAA-certified aerobatic and helicopter piston engines on the market.

Contents

Design and development

The O-340 was designed by Lycoming specifically for the TEMCO-Riley D-16A Twin Navion project. Jack Riley, the designer of that aircraft was interested in an upgraded version of the Lycoming O-320 that would produce more power to give the Twin Navion a better single-engine service ceiling. The Lycoming O-360 was still years away in development and so a modification of the O-320 was undertaken by Lycoming. The O-320 received longer cylinder barrels and a crankshaft with a longer stroke to increase displacement and different piston connecting rods. This increased the compression to 8.5:1 and boosted power output to 170 hp (127 kW) over the O-320's 150 hp (112 kW). The engine was later used in a number of airplanes and helicopters and also in amateur-built aircraft designs. [1]

Lycoming O-320 family of flat-four piston aircraft engines

The Lycoming O-320 is a large family of 92 different naturally aspirated, air-cooled, four-cylinder, direct-drive engines commonly used on light aircraft such as the Cessna 172 and Piper Cherokee. Different variants are rated for 150 or 160 horsepower. As implied by the engine's name, its cylinders are arranged in horizontally opposed configuration and a displacement of 320 cubic inches (5.24 L).

Lycoming O-360 flat-four piston aircraft engine family by Lycoming

The Lycoming O-360 is a family of four-cylinder, direct-drive, horizontally opposed, air-cooled, piston aircraft engines. Engines in the O-360 series produce between 145 and 225 horsepower, with the basic O-360 producing 180.

The O-340 family of engines covers a range from 160 hp (119 kW) to 170 hp (127 kW). All have a displacement of 340.4 cubic inches (5.58 litres) and the cylinders have air-cooled heads. [2]

Engine displacement

Engine displacement is the swept volume of all the pistons inside the cylinders of a reciprocating engine in a single movement from top dead centre (TDC) to bottom dead centre (BDC). It is commonly specified in cubic centimetres, litres (L), or cubic inches (CID). Engine displacement does not include the total volume of the combustion chamber.

Cylinder head Component of a cylinder of an internal combustion engine

In an internal combustion engine, the cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket. In most engines, the head also provides space for the passages that feed air and fuel to the cylinder, and that allow the exhaust to escape. The head can also be a place to mount the valves, spark plugs, and fuel injectors.

The O-340 series was certified under Type Certificate E-277 and first approved on 20 July 1954. The engines are approved for both tractor and pusher applications. [2]

A type certificate signifies the airworthiness of a particular category of aircraft, according to its manufacturing design (‘type’). It confirms that the aircraft is manufactured according to an approved design, and that the design ensures compliance with airworthiness requirements.

Tractor configuration arrangement of propellers on an aircraft to face forward

An aircraft constructed with a tractor configuration has the engine mounted with the airscrew in front of it so that the aircraft is "pulled" through the air, as opposed to the pusher configuration, in which the airscrew is behind and propels the aircraft forward. Through common usage, the word "propeller" has come to mean any airscrew, whether it actually propels or pulls the plane.

Pusher configuration arrangement of propellers on an aircraft to face rearward

In a vehicle with a pusher configuration, the propeller(s) are mounted behind their respective engine(s). According to British aviation author Bill Gunston, a "pusher propeller" is one mounted behind the engine, so that the drive shaft is in compression.

Variants

O-340-A1A
Four-cylinder, horizontally opposed, 340.4 cubic inches (5.58 litres), 170 hp (127 kW) at 2700, dry weight 250 lb (113 kg), Marvel-Schebler MA-4-5 carburetor, Scintilla S4LN-20 and S4LN-21 magneto. Minimum fuel grade 91/96 avgas. Certified on 13 January 1955. [2]
O-340-A2A
Four-cylinder, horizontally opposed, 340.4 cubic inches (5.58 litres), 170 hp (127 kW) at 2700, dry weight 250 lb (113 kg), Marvel-Schebler MA-4-5 carburetor, Scintilla S4LN-20 and S4LN-21 magneto. Minimum fuel grade 91/96 avgas. Identical to the A1A but with no provision for a hydraulic propeller control. Certified on 16 November 1956. [2]
O-340-B1A
Four-cylinder, horizontally opposed, 340.4 cubic inches (5.58 litres), 160 hp (119 kW) at 2700, dry weight 247 lb (112 kg), Marvel-Schebler MA-4-5 carburetor, Scintilla S4LN-20 and S4LN-21 magneto. Minimum fuel grade 80/87 avgas. Identical to the A1A except with a reduced 7.15:1 compression ratio and 160 hp to run on 80/87 fuel. Certified on 20 July 1954. The O-340-B1A was originally certified as just the "O-340", but the designation was changed to "O-340-B1A" on 27 September 1956. [2]

Applications

Brantly B-2

The Brantly B-2 is an American two-seat light helicopter produced by the Brantly Helicopter Corporation.

Cessna 170 airplane

The Cessna 170 is a light, single-engined, general aviation aircraft produced by the Cessna Aircraft Company between 1948 and 1956.

Specifications (O-340-A1A)

Data from TYPE CERTIFICATE DATA SHEET NO. E-277, Revision 5 [2]

General characteristics

Components

Performance

See also

Related lists

Related Research Articles

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References

  1. 1 2 3 4 5 6 7 8 twinnavion.com (n.d.). "An O-340? What's that?" . Retrieved 2009-04-19.
  2. 1 2 3 4 5 6 7 Federal Aviation Administration (April 1963). "TYPE CERTIFICATE DATA SHEET NO. E-277, Revision 5" . Retrieved 2009-04-19.


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