Marsden Gemini

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Role Glider
National origin Canada
Designer Dr. David Marsden
First flight 1973
Status Production completed
Number built one

The Marsden Gemini is a Canadian mid-wing, T-tailed, two-seats in side-by-side configuration, experimental research glider that was designed and constructed by Dr. David Marsden at the University of Alberta, first flying in 1973.[1][2]

Design and development[edit]

The Gemini was designed to explore the use of flaps to create a variable geometry sailplane that would be optimized for both low speed thermalling flight and also high speed gliding between thermals.[1][2]

The aircraft was predominantly made from aluminium, with some stainless steel used for the wing ribs, controls and fittings. The two-place side-by-side cockpit was made from fibreglass. Its four-piece 60.75 ft (18.5 m) span high aspect ratio wing employed a modified Wortmann FX-61-163/35SF airfoil. The Fowler flaps occupied the entire trailing edge of the wing and accounted for 35% of the wing chord. In cruise the flaps were retracted, reducing the wing area. While climbing, the flaps were extended, producing a high lift coefficient of 2.2. For glidepath control when landing the flaps deployed to 80° to create aerodynamic drag. The outer flaps acted as slotted ailerons for roll control.[1][3]

Only one Gemini was built.[1][2] The aircraft is still operational and as of August 2011, owned by Gary Osoba of Wichita, Kansas, United States.[4]

Operational history[edit]

The aircraft was flown to set seven Canadian multi-place records, including the record for speed over a 500 km (311 mi) triangle. It was also used to set the US national record for the 300 km (186 mi) of 94 mph (151 km/h).[1][2]

On July 2, 2011, Osoba and his wife Christine flew the Gemini on a 565 mi (909 km) free distance flight from Zapata, Texas to just east of Amarillo, Texas, a flight which won the 2011 Barringer Trophy.[5][6]

Specifications (Gemini)[edit]

Data from Sailplane Directory[1]

General characteristics

  • Crew: one
  • Capacity: one passenger
  • Wingspan: 60 ft 8 in (18.49 m)
  • Wing area: 124 sq ft (11.5 m2) with flaps retracted
  • Aspect ratio: 29.8:1
  • Airfoil: modified Wortmann FX-61-163/35SF
  • Empty weight: 785 lb (356 kg)
  • Gross weight: 1,240 lb (562 kg)


  • Maximum glide ratio: 40:1 at 74 mph (119 km/h)
  • Rate of sink: 124 ft/min (0.63 m/s)
  • Wing loading: 10 lb/sq ft (49 kg/m2)

See also[edit]

Other gliders with Fowler flaps

Related lists


  1. ^ a b c d e f Activate Media (2006). "Gemini Marsden". Retrieved 15 August 2011. 
  2. ^ a b c d Armstrong, Ken (August 2011). "Capt. Ken's comments - July". Canadian Owners and Pilots Association. Retrieved 15 August 2011. 
  3. ^ Lednicer, David (2010). "The Incomplete Guide to Airfoil Usage". Retrieved 1 August 2011. 
  4. ^ "FAA Registry N Number Query Results - N77ZV". Retrieved 23 August 2011. 
  5. ^ "July 2 OLC". Retrieved 23 August 2011. 
  6. ^ "The Lewin B. Barringer Memorial Trophy". Retrieved 9 May 2012.