Beechcraft Model 18

Beechcraft 18 on floats.

The Beechcraft Model 18 was a small six- to 11-place, twin-engine, low-wing, conventional-gear aircraft manufactured by the Beech Aircraft Corporation of Wichita, Kansas. Construction was all-metal semi-monocoque with fabric covered control surfaces. This model saw service during and after World War II in a number of versions including the C-45 Expeditor and AT-11 Kansan for the United States Army Air Corps and SNB for the United States Navy. An estimated aggregate total time in service for the aircraft time is in excess of 20,000,000 hours of flight time.

The Beech 18 is the not only has the longest production run (1937-1970) of any aircraft ever built but is the most modified with over 200 FAA approved 337's (Supplemental Type Certificates)on record for the aircraft.The aircraft uses have included aerial spraying, sterile bug release, fish seeding, dry ice cloud seeding, aerial fire fighting, airborne mail pick up and drop, ambulance service, numerous movie productions, skydiving, frieght, gun and drug smuggling, engine test bed, skywriting and banner tow. A number of them were operated as passenger aircraft, and many are now in private hands as highly prized collectibles.

Operational history

The aircraft has used a variety of engines and has had a number of airframe modifications to increase gross wieght and speed. At least one aircraft was modified to a 600 horse power R-1340 Pratt and Whitney powerplant configuration. The added wieght of approximately 200 pounds per engine with R-1340 engine was not satisfactory due to the weakest structural area of the aircraft being the engine mounts. With the exception of the center truss, the central component around which the entire aircraft is built, nearly every airframe component has been modified at one time or another.

While legendary for rugged construction, in the event of a very hard (crash) landing it is not uncommon for an engine to snap off the mount and roll ahead of the wreckage like a large bowling ball. In one instance in 1996 a California skydiving operator landed in a plowed field during a forced landing due to fuel exhaustion. One engine rolled nearly 500 feet ahead of the airplane while the other smashed through the tail plane. The pilot walked out unharmed and the airplane was successfully sold for scrap.

Some aircraft were almost unrecognizable as having originated as a Beech 18. In one case the aircraft was modified to a triple tail, tri-gear, hump backed configuration and appeared similar to a miniature Lockheed Constellation.

Some of the modifications created by independent engineering entreprenuers were adopted in concept by the factory in later production versions in similar fashion to the current practice Harley Davidson copying of custom motorcycles built in the 1960's and 1970's. Among the most notable cooling air and exhaust modifications were those engineered by Benjamin Isreal while employed by Conrad Conversions. His modifications were based largely on creating a more efficient use of cooling air to reduce cooling drag, a major detriment to aircraft cruise performance. The difference in cruise performance was a significant 10% or better at the same power settings as before the modifications. These modifications were largely copied on the factory produced G and H models.

This D-18S Beech is used frequently for nostalgic skydiving events in the southwestern United States. It was a corporate aircraft for Lay's Potatoe Chips in the 1950's

A factory option at one point was the addition of JATO bottles on each engine nacelle which added the equivalent of 200 horse power per engine for about 12 seconds. The most successful powerplant upgrade was that of the Pratt and Whitney turbine PT-6 engine and Hartzell propellor. The combination of engine and propellor successfully extended the commercial life of an aging aircraft. A number of these turbine conversions are still flying on freight, skydiving or med-fly abatement assignments.

Military Operators

* Argentina, Bolivia, Brazil, Canada, China, Colombia, Costa Rica, the Dominican Republic, Ecuador, El Salvador, France, Guatemala, Honduras, Indonesia, Italy, India, Ivory Coast, Mexico, Netherlands, Nicaragua, Niger, Peru, Philippines, Portugal, Somalia, Sri Lanka, Sweden, Turkey, United Kingdom (Royal Air Force, Royal Navy), United States (Army, Army Air Corps, Army Air Force, Air Force, Marine Corps, Navy), Uruguay, Venezuela, Zaire

Specifications (UC-45 Expeditor)

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