The St Croix Excelsior ( en, ever higher) is an American

ultralight aircraft Ultralight aviation (called microlight aviation in some countries) is the flying of lightweight, 1- or 2-seat fixed-wing aircraft. Some countries differentiate between weight-shift control and conventional three-axis control aircraft with aile ...

that was designed by Chad Wille and Charles Wille, produced by

St Croix Aircraft St Croix Aircraft, was an American manufacturer of wooden propellers for homebuilt and ultralight aircraft and a supplier of aircraft plans and kits. The company headquarters was located in Corning, Iowa.Purdy, Don: ''AeroCrafter - Homebuilt A ...

Corning, Iowa Corning is a city in Quincy Township, Adams County, Iowa, United States. The population was 1,564 at the 2020 census. It is the county seat of Adams County. Corning is located just north of the intersection of U.S. Route 34 and Iowa Highway 148 ...

and first flown in 1980. The aircraft was supplied in the form of plans for amateur construction with some hard-to-make parts available as well as partial kits.Purdy, Don: ''AeroCrafter - Homebuilt Aircraft Sourcebook'', page 247. BAI Communications. Cliche, Andre: ''Ultralight Aircraft Shopper's Guide'' 8th Edition, page E-15. Cybair Limited Publishing, 2001. Downey, Julia: ''1999 Plans Aircraft Directory'', Kitplanes, Volume 16, Number 1, January 1999, page 67. Primedia Publications. ISSN 0891-1851

Design and development

The Excelsior was designed to comply with the US FAR 103 Ultralight Vehicles rules, including the category's maximum empty weight of . The aircraft has a standard empty weight of . It features a strut-braced

high-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 conf ...

, a single-seat, open cockpit,

tricycle landing gear Tricycle gear is a type of aircraft undercarriage, or ''landing gear'', arranged in a tricycle fashion. The tricycle arrangement has a single nose wheel in the front, and two or more main wheels slightly aft of the center of gravity. Tricycle ...

and a single engine in

pusher configuration In an aircraft with a pusher configuration (as opposed to a tractor configuration), the propeller(s) are mounted behind their respective engine(s). Since a pusher propeller is mounted behind the engine, the drive shaft is in compression in no ...

. The aircraft fuselage is made from welded

4130 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 ...

tubing, with the wings and tail built from

rivet A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite to the head is called the ''tail''. On installation, the rivet is placed in a punched ...

ed sheet

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It h ...

, aluminum tubing and covered with doped

aircraft fabric covering Aircraft fabric covering is a term used for both the material used and the process of covering aircraft open structures. It is also used for reinforcing closed plywood structures. The de Havilland Mosquito is an example of this technique, as are ...

. Its straight

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, ...

, tapered

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 199 ...

, span wing is braced with a single

lift strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...

per side. The pilot sits in an open cockpit, with a small windshield. The engine and tail configuration are unconventional. The specified Zenoah G25 engine is mounted on top of the high wing and drives the tail-mounted propeller through a flexible extension shaft, that is designed to eliminate vibrations. 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 ...

and

elevator 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 ar ...

are mounted on top of the rear fuselage, with the fin and rudder mounted below the tailplane, providing protection for the propeller from contacting the ground. The controls are conventional, except that roll control is provided by spoilers, rather than

aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement arou ...

s. The

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 ...

consists of suspended main gear, a nose wheel and a rudder-mounted rear skid. The aircraft has enough

gliding Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word ''soaring'' is ...

performance to be soared. The construction time from the plans is estimated at 400 hours. Plans were intermittently available between 1980 and about 2000, but from 2001 the design was not advertised as being available by the company any longer.Downey, Julia: ''2001 Plans Aircraft Directory'', Kitplanes, Volume 18, Number 1, January 2001, page 28. Kitplanes Acquisition Company. ISSN 0891-1851

Specifications (Excelsior)

References

External links

Photo of an Excelsior
{{St Croix aircraft Excelsior 1980s United States ultralight aircraft Homebuilt aircraft Single-engined pusher aircraft