The Helio Courier could maintain control at speeds as low as 27 miles per hour (43В km/h). In conjunction with the leading-edge slats, 74% of the trailing edge incorporates high-lift slotted flaps, which together with interrupter blades atop each wing when roll control is lost at very low airspeed, allows for a tight turning radius. The slats contribute to the Helio's outstanding short takeoff and landing (STOL) capability, and allow for stall/spin-proof controllable flight.

The wings are of conventional aluminum construction, but feature Handley Page leading-edge slats that deploy automatically when the aircraft's airspeed falls below a certain valueВ - 55 to 60 miles per hour (89 to 97В km/h). The demonstrator's first flight took place on April 8, 1949, flying from what was then called the Boston Metropolitan Airport, an airport located within the greater Boston suburban town of Canton, Massachusetts which was closed at the end of the 1960s, after the opening of nearby Norwood Memorial Airport (only 1.5 miles (2.5 km) NNW of the Canton facility), which itself first opened as an emergency WW II airfield in 1942.ДЇor the construction of the production Courier aircraft, its all aluminum-clad airframe features a welded 15G steel-tube center section fuselage, with shoulder harnesses that protect the occupants in an emergency.

The powerplant for the demonstrator was switched to the Continental C85 boxer-four cylinder air-cooled engine, upgraded with fuel-injection, and uniquely equipped with a multi-belt speed reduction unit to drive its Aeroproducts nine-foot (2.75 meter) diameter, variable-pitch two-blade propeller, which contributed greatly to the amazing STOL flight characteristics of the demonstrator aircraft. Only the cabin area of the PA-17's original airframe remained unmodified, with the fuselage lengthened by four feet (1.2 meters), given a taller fin-rudder unit, clipped the Vagabond's stock 29 ft-3 inch (8.92 meter) wingspan down to only some 28.5 feet (8.7 meters), fitted the shortened wings with full-span leading-edge slats, long-span wing flaps that forced the ailerons to be much diminished in size, and a longer-travel main landing gear of a taller design, not unlike that of the 1930s-origin Fieseler Fi 156 German military STOL pioneer aircraft. The demonstrator for the Courier's concept, 'Helioplane #1', was converted by the then-local Wiggins Airways firm from a Piper PA-17 Vagabond Trainer, one of the so-named 'short-wing Pipers' in production following World War II. Koppen went on to design the Helio Courier. Koppen designed aircraft for the Stout Metal Airplane Division of the Ford Motor Company, including the Ford Flivver, an aircraft that was supposed to be mass-produced by Ford.

Helio courier