Model Number

F3J

1. The 18th letter in the Greek alphabet (Σ, σ)
2. Maths the symbol Σ, indicating summation

This sailplane like all of my designs was developed over many years, and like its name suggests has been the sum of all I knew with each version.

Beginning in 1985 with the Sigma I prototype that was intended for and proved to be quite successful at MOM pylon racing, this new version comes with a good pedigree that I hope it will continue to bear out.

The aerofoil section used for the wings – JH35 series – has been designed for constantly changing flaps and has been thoroughly tested in a professional wind tunnel. The aerofoil profile is quite different to most that are flying today and is designed to get you up as fast as possible, keep you there as long as possible, but at the same time when reflexed, go as fast as possible.

With its long nose and generous moments the Sigma II gives good lateral response while saving nose weight needed to compensate. Wings are elliptical to provide optimum lift distribution, while the removable tailplanes are designed to give exactly correct compensation with minimum drag penalty.

Other than the more technical aspects, this plane just looks right and that is generally a very good performance indicator.

Available in both F3B and F3J versions (3.1M span and 3.7M respectively) the plane is completely CAD designed and CNC moulded and comes highly finished with a full set of hardware and a large 20mm ID ballast tube installed.

SiΣma II  Specifications (F3b & F3j)

Span: 3.1 and 3.7m respectively
Length: 1.63m
Aerofoils: JH35 series, 8%, 7.5%, 7% elliptically blended.
Controls: Ailerons, Elevators, Flaps, Rudder