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. The demonstrator's first flight took place on April 8, 1949, flying from what was then called the Boston Metropolitan Airport. For 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 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 value — 55 to 60 miles per hour (89 to 97 km/h). The slats contribute to the Helio's outstanding short takeoff and landing capability, and allow for stall/spin-proof controllable flight. 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 Helio Courier could maintain control at speeds as low as . The design of the Helio features a large vertical tail surface and rudder for control at very low flight speeds. However, on conventional geared aircraft (taildraggers), the airplane tends to be sensitive to crosswinds, thus a crosswind gear option is available, allowing the main tires to caster left or right 20 degrees, increasing the crosswind component to . The Helio has its main gear placement far forward of the cabin, enabling hard braking on unprepared landing areas. A tricycle-gear model was produced, but is unsuitable for unprepared rough terrain. Helios are also capable of being equipped with floats; both straight and amphibious floats being offered. Operational history With a minimum-control speed of around 28 mph, the Courier is perfectly suited for confined off-airport operations. The first one was certified in July 1954 and powered by the 260 hp Lycoming GO-435-C2B2. The first production Courier (Serial Number 001, dubbed "Ol' Number 1")C-G001 was previously owned and operated by JAARS as N242B until 2010. Jaars Helio Courier has been a frequent airshow performer at EAA AirVenture Oshkosh for decades, displaying its slow flight capability in front of thousands and serving as a drop plane for the Liberty Parachute Team.