Grob G104 Speed Astir

The Grob G104 Speed Astir was a competition sailplane produced in Germany in the late 1970s as Grob's first design in the 15 metre class. 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 created by the gap between the wing trailing edge and a deployed flap by attaching the highly-elastic skin of the wing to the flap itself, so that when the flap was deployed, this skin would stretch over the gap that would normally be created.

G104 Speed Astir and Speed Astir II
Speed Astir IIb in flight
Role 15 metre class sailplane
National origin Germany
Manufacturer Grob Aircraft
Designer Burkhart Grob
First flight April 1978
Number built 108
External image
Grob G104 Speed Astir IIb taking off on aerotow

The original Speed Astir flew in early 1978, but was replaced in production by the end of the year by a refined design named the Speed Astir II. 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. Production of all variants was discontinued shortly thereafter.


Specifications (Speed Astir II)

General characteristics

  • Crew: One pilot
  • Length: 6.69 m (21 ft 11 in)
  • Wingspan: 15.00 m (49 ft 3 in)
  • Height: 1.27 m (4 ft 2 in)
  • Wing area: 11.5 m2 (124 sq ft)
  • Aspect ratio: 19.6
  • Empty weight: 265 kg (584 lb)
  • Gross weight: 515 kg (1,135 lb)

Performance

  • Maximum speed: 270 km/h (168 mph, 146 kn)
  • Maximum glide ratio: 41.5
  • Rate of sink: 0.60 m/s (120 ft/min)

gollark: It does not block the entire output of the sun. You can tell this by looking outdoors depending on time of day.
gollark: It's not like it magically goes to the V O I D.
gollark: Wouldn't it just *absorb* it, not *block* it?
gollark: As far as I know, water vapour does have a big effect on heating but is regulated by feedback loops which don't control CO2.
gollark: If they behaved *really* differently, stuff like weather balloons and satellites would fail in bizarre ways.

References
  • Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. p. 441.
  • Hardy, Michael (1982). Gliders and Sailplanes of the World. Shepperton: Ian Allan. pp. 49–50.
  • Homepage of Grob Aircraft
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