The Sling 4 concept emerged from the performance of the standard Airplane Factory Sling 2 trip around the world in 2009.
Conceived as a 1320 lbs Maximum All Up Weight “light sport” aircraft, it was soon clear that, even with a normally aspirated 100hp motor, the standard Sling was able to climb and perform well right up to 2138 lbs.
The first consequence is that The Airplane Factory Team performed all the required tests and approved the standard aircraft at 1543 lbs MAUW. We also simultaneously commenced work on development of a light 4 seater version of the same aircraft.
The chief differences between the Sling 2 and the Sling 4 are the wing size, the engine and the centre fuselage arrangements. Where the standard Sling customarily uses a 100hp Rotax 912 ULS or iS engine, the Sling 4 ais fitted with the 115hp turbocharged Rotax 914 UL engine.
Although a 15hp difference doesn’t sound like the world, the turbocharged engine gives full power at up to 15 000 feet, at which altitude the 100hp would only be delivering approximately 55hp. So, on a hot day the swing in power between the 912 ULS and 914 UL engine is in the vicinity of 36%, not just 15%.