Glass wing 604 Kestrel

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Glass wing 604 Kestrel
Glass wing 604 (D-2085)
Type: Glider
Design country:

Germany Federal RepublicFederal Republic of Germany BR Germany

Manufacturer:

Glass wing

First flight:

April 30, 1970

Production time:

1970-1973

Number of pieces:

10

The Glasflügel 604 Kestrel is a single-seat glider manufactured by Glasflügel Segelflugzeugbau GmbH . The gliding index is 114 for the 22 m version and 118 for the 24 m version.

history

The glass wing 604 is aerodynamically and conceptually based on the 401 Kestrel constructed by Josef Prasser and Dieter Althaus in 1968 and was originally planned as a test vehicle for a two-seater. The span was increased from 17 to 22 meters. The hull was lengthened by almost a meter. The aircraft also received an enlarged elevator and vertical stabilizer. The prototype of the Glasflügel 604 took off after only four months of development with Huldreich Müller on April 30, 1970 at the Karlsruhe-Forchheim airfield on its successful maiden flight.

The flight performance and characteristics of the prototype were so promising that after only minor modifications to the prototype (lengthening the fuselage by a few cm and improving the rudder adjustment), Glasflügel decided to build the single-seater in series. The wing of the glass wing 604 is divided into three parts. At around 272 kg it is very heavy; the middle part alone weighs over 160 kg. The wing has a six-part flap , whereby the outer flaps are controlled in a ratio of 1: 2 with the ailerons . Operating the outer ailerons does not affect the inner flaps and flaps. At the same time, the ailerons and flaps are superimposed in such a way that when the inner flaps are in the landing position (+ 35 °) there is a strong twist of the wing. This means that the aircraft can also be safely controlled in slow flight. In addition to the usual landing aids such as spoilers and landing flaps, the glider has an additional dropping brake parachute in the rudder. This enables very steep approaches without a significant increase in speed. In contrast to the other open class gliders, the 604 had quite balanced flight and control characteristics in its time and impressed with its maneuverability, which was pronounced for the size and weight of the aircraft. At the same time, it impressed with its excellent performance potential, but was only reserved for a small group of glider pilots due to the small number of units and the high price.

Although the cockpit is equipped with many controls, it is characterized by a high level of ergonomics - it is very spacious and comfortable. Only the bridge of the two-part cockpit canopy is annoying - two of the 604 glass wings approved in Germany have now been equipped with a continuous one-piece canopy (D-6604 and D-2085). The aircraft also has completely internal rudder drives - an aerodynamically favorable, but very complex construction detail that can only be found in this version in gliders from Glasflügel.

The first flight took place in the spring of 1970. Just a few weeks later, Walter Neubert took sixth place at the World Championships in Marfa / USA with the prototype D-0604 (despite a competition day that was canceled for him). With this aircraft, Walter Neubert flew a world speed record in Kenya over a 300 km triangle with a cutting speed of 153 km / h after he had already improved the record over a 100 km triangle to 155 km / h in early July 1970.

Bert Zegels was able to achieve second place in the open class on the Glasflügel 604 at the World Gliding Championship in 1974; at the 1976 World Cup, Dick Butler came fifth in Open Class with this aircraft. Despite its success and exceptional flight performance for the time, the glass wing 604 was only manufactured ten times by the end of 1973; Design and manufacture were too expensive and time-consuming. At least three copies were stationed in Italy in the 1970s, two of which were temporarily owned by Adele and Giorgio Orsi from Calcinate near Varese (work numbers 4 and 6).

Today there are again five copies in Germany - of which currently (10/2012) four, WNr. 2 D-0279, WNr. 4, D-6604; WNr. 6, D-5720; WNr. 9, D-2085 in airworthy condition. Work number 2 was in Dunstable / England with the BGA registration number 2585. This machine has had a German registration since 2008 with the former registration number D-0279 and has been stationed in Ulm since September 2009. Home airfield of No. 6, D-5720 is Grabenstetten on the Swabian Alb. Only one glass wing 604 has been registered without interruption since its first flight in 1973 under the same registration number (WNr. 9, D-2085; today stationed in Nastätten in the Taunus). WNr. 10, formerly I-ALTI, is currently being restored to airworthy condition in Pirmasens and is approved in Germany under D-2109. Five copies are native to the USA. At least one of the latter is in an airworthy condition owned by Steven Leonard (WNr. 8, N57L). The other 604 matriculated in the USA are: WNr. 1 (prototype, formerly D-0604) as N62301, WNr. 3 as N165D, WNr. 5 as N854A and WNr. 7 as N604VP. WNr. 1, 3, 5, 7 are owned by James Turrell / Arizona. The author is currently not aware of their condition.

The Glasflügel 604 was the most powerful (and most expensive) glider built in series in GRP and was only replaced in its performance class in 1981 by the new developments ASW 22 and Nimbus 3 . For serial number 2, a shorter center section for a 20 m version was built and tested around 1972 at the instigation of Walter Neubert. This was last stationed in Ulm. One specimen was enlarged to a span of 24 m. This is the largest glider ever built in fiberglass (No. 4, D-6604, formerly D-7004; today it is based in ceiling Pfronn).

All subsequently built open class gliders use the much stronger and lighter carbon fiber in the wing. This made it possible to achieve thinner airfoil profiles as well as even larger spans and airfoil extensions, which resulted in lower air resistance and thus in the early 1980s a 10 to 15 percent higher maximum glide ratio and a slightly lower self-sinking. Today's top designs in the open class, such as the Eta, achieve glide ratios of 65.

Further use of the glass wing 604 forms

AK-2

The Akaflieg Karlsruhe developed on the basis of the wings and fuselage 604, the concept of a glider with retractable engine, where the engine remains in the body. This was a novelty in the 1970s. The AK-2 project was canceled in favor of the AK-5 due to technical difficulties with the engine and power transmission.

AK-5 / 5b

Akaflieg then developed two gliders with a wingspan of 15 meters, the AK-5 and AK-5b, based on the fuselage of the glass wings 604 .

fs 31, B12, B13

The tail units of the glass wings 604 were used for the tail unit occupancy of the fuselage of the fs 31 of Akaflieg Stuttgart. The contour of the horizontal stabilizer was used in the Berlin aircraft developments B12 and B13 .

Technical specifications

Parameter Data
Constructors Eugen Hänle / Josef Prasser / Dieter Althaus
crew 1
Hull length 7.56 m
span 22.00 m
Wing area 16.26 m²
Wing extension 29.8
Tail unit T-tail
Construction GfK
Empty mass 455 kg
Max. Payload in the fuselage 130 kg
Max. Water ballast 100 kg
Max. Takeoff mass 650 kg
Wing loading 34-40 kg / m²
v min 66 km / h
v ne 250 km / h
v max winch 130 km / h
v max F-tow 150 km / h
Slightest sinking 0.53 m / s at 75 km / h and 34 kg / m²
Glide ratio 49 at 105 km / h and 40 kg / m², according to Idaflieg measurement (D-2085)
Wing profile Wortmann FX-67-K-170 thickened to approx. 20% at the root for static reasons, towards the edge curve to Wortmann FX-67-K-150

Web links

swell

  • Aircraft data sheet
  • Dietmar Geistmann: The development of plastic gliders. ISBN 3-87943-483-2 .
  • Dietmar Geistmann: Gliders in Germany. ISBN 3-613-01449-1 .
  • Test report Glasflügel 604. Flug Revue Dec. 1972
  • Martin Simons: Gliders 1965-2000. ISBN 3-9808838-0-9 .
  • Flight u. Operating manual # 9 D-2085


Individual evidence

  1. ↑ a b History of the company Glasflügel Segelflugzeugbau GmbH / Schlattstall. Glasfaser-Flugzeug-Service GmbH , accessed on March 1, 2012 .
  2. ↑ Akaflieg Karlsruhe: AK-2 "The Unfinished". Retrieved September 11, 2015 .