|National origin||West Germany|
|First flight||early 1970|
|Status||No longer in production|
|Developed from||Glasflügel Kestrel 17|
Design and development
The 604 was originally intended as a test aircraft for a proposed two-seat glider that was never built. The prototype did so well in competition that a ten-aircraft production run was completed, resulting in a total of eleven 604s being completed, including the prototype.
Due to the aircraft's huge size, including its 22.0 m (72.2 ft) three-piece wing that weighs over 272 kg (600 lb), the aircraft picked up the nickname "the Jumbo". The wing centre section alone weighs 115 kg (254 lb), making rigging it for flight a chore that requires a large crew.
The 604 is constructed from fibreglass. The wing employs a modified Wortmann FX 67-K-170 airfoil at the wing root, changing to a Wortmann FX 67-K-150 at the wing tip. The wing features six flaps, with the outer pair moving at a 2:1 differential ratio with the ailerons. For glidepath control the 604 has wing top-surface spoilers and a tail-mounted drag chute. The aircraft can carry 100 kg (220 lb) of water ballast. The landing gear is a retractable monowheel.
The 604 prototype, flown by Walter Neubert, came in sixth in the 1970 World Gliding Championships held at Marfa, Texas, even though the pilot was lost overnight after a land-out during the competition and missed the following day. A 604 came second in the Open Class at the 1974 World Championships held at Waikerie, South Australia. The aircraft also set several world records between 1970 and 1974.
- Crew: one
- Wingspan: 22.0 m (72 ft 2 in)
- Wing area: 16.3 m2 (175 sq ft)
- Aspect ratio: 29.8:1
- Airfoil: Wing root: Wortmann FX 67-K-170 mod, wing tip: Wortmann FX 67-K-150
- Empty weight: 420 kg (926 lb)
- Gross weight: 600 kg (1,323 lb)
- Never exceed speed: 249 km/h; 135 kn (155 mph) in rough air
- Maximum glide ratio: 49:1 at 61 mph (98 km/h)
- Rate of sink: 0.50 m/s (98 ft/min) at 45 mph (72 km/h)
- Wing loading: 37.0 kg/m2 (7.57 lb/sq ft)
- Aircraft of comparable role, configuration and era
- Related lists
- Activate Media (2006). "604 Glasflugel". Retrieved 11 July 2011.
- Said, Bob: 1983 Sailplane Directory, Soaring Magazine, page 81, Soaring Society of America November 1983. USPS 499-920
- Lednicer, David (2010). "The Incomplete Guide to Airfoil Usage". Retrieved 11 July 2011.
- Griffith Jr., Marion (February 1982). "645 Miles in a 604". Soaring 46 (2): 41–44.
- Federal Aviation Administration (July 2011). "Make / Model Inquiry Results Glasflugal 604". Retrieved 11 July 2011.