Helio
 
U-10
Super Courier
 

The Koppen-Bollinger Aircraft Corporation was founded by Otto Koppen and Lynn Bollinger in Massachusetts in 1948 to develop a light STOL utility aircraft. It was renamed the Helio Aircraft Corporation by the time manufacture of the Courier commenced in the early 1950s at a plant in Pittsburg, Kansas.

The business was bought by the General Aircraft Corporation in 1969, was renamed Helio Aircraft Company and continued production until 1974, when General Aircraft commenced legal proceedings against the CIA, alleging that the agency had planned to ruin the business through organizing unlicensed production of the Courier. During the 1970s, the rights changed hands several times before being purchased by Helio Aircraft Ltd , which returned the Courier to production in the 1980s, but only built 18 aircraft.

The rights to the Courier and Stallion were bought and sold a number of times more before being purchased by Helio Aircraft LLC of Prescott, Arizona, which announced plans in 2004 to return both types to production.

Variants

Koppen-Bollinger Helioplane.
Original prototype soon re-named Helio Courier.
Helioplane Four.
unknown possible variant.
Helioplane Two.
unknown possible variant.
Hi-Vision Courier.
unknown possible variant.
H-291.
Prototype, one built.
H-295 Super Courier.
Variant with a Lycoming GO-480-G1D6, purchased by USAF as U-10D, 173 built.
HT-295 Super Courier or Trigear Courier.
H-295 with tricycle undercarriage, 19 built.
H-250 Courier.
H-295 with lengthened fuselage and Lycoming O-540-A1A5 engine, 41 built.
H-391 Courier.
Prototype with Lycoming GO-435-C2 engine, one built.
H-391B Courier.
Production version of H-391, 102 built.
H-392 Strato Courier.
High-altitude version of H-391 with Lycoming GSO-480-A1A5 engine (340 hp).
H-395 Super Courier.
H-391B with Lycoming GO-480-G1D6, purchased by USAF as U-10A and U-10B, 138 built.
H-395A Courier.
Variant of the H-395 with a Lycoming GO-435-C2B6 engine, seven built.
H-500 Twin Courier.
Twin-engined H-395 for the CIA. Very little information available except seven delivered to the CIA under front designation U-5.
Helio H-550 Stallion.
Turboprop powered development
H-580 Twin Courier.
A longer nosed H-500 with twin wing mounted piston engines, five built.
H-634 Twin Stallion
Planned twin Allison C250 powered Stallion.
H-700 Courier.
H-295 with redesigned wing and undercarriage and Lycoming TIO-540-J2B engine.
H-800 Courier.
H-700 with Lycoming IO-720-A1B engine, 18 built (H-700 and H-800 together).
L-24 Courier.
Military version of the H-391 Courier.
L-28 Courier.
Military version of the H-395 Courier.
U-5 Twin Courier.
Probable front designation for CIA Twin Couriers.
U-10 Courier
Re-designation of L-28 Courier
U-24 Stallion
Military designation for H-550 Stallion

Source: Wikipedia