Taking the G102 Astir design as a starting point, the Speed Astir featured a new wing of narrower chord and different section, a fin and rudder of reduced height, capacity for 150 kg (330 lb) of water ballast, and "elastic flaps".

This latter feature eliminated the drag normally associated with the air gap between the wing and a deployed flap.

It did this by extending the wing skin over the entire upper surface so the highly flexible skin served as the flap hinge and there was no air gap between the flap and the remainder of the wing.

This had a slimmer, laminar-flow fuselage and made use of carbon fibre in its construction.

A version with a lengthened fuselage for taller pilots and incorporating carbon fibre wing spars was made available in 1979 as the IIB, along with an increased-span version of the IIB as the II 17.5.