Steen
 
Skybolt
 

The Steen Skybolt is an American homebuilt aerobatic biplane. Designed by Lamar Steen as a high school engineering project, the prototype first flew in October 1970.

Variants

Skybolt (S)
The standard Skybolt as originally released for home-building
Skybolt (D)
A revised structure and capability to have engines from 180 to 350 hp (134 to 261 kW) fitted.
Skybolt (R)
A radial engined derivative, with revised fusellage plus the improved structure of the (D), fitted with either a 360 hp (268 kW) Vedeneyev M14P or a 400 hp (298 kW) Vedeneyev M14PF nine-cylinder radial.
Skybolt 300
A derivative of the Skybolt fitted with a 300 hp (224 kW) engine.
Super Skybolt
A two seater version created by John Shipler by amalgamating a Pitts S-2 with a Skybolt, the prototype of which is named Storm Warning.

Source: Wikipedia