The Eta is the customized Bentley of gliders. It is huge, beautiful, and costs over a million dollars. The controls and interior are taken from the high performance ASH-25. Dr. Reiner Kickert is heading the design team. The sugar daddy behind it all is Hans Werner Grosse, among others. Grosse is a record setting pilot himself. The plane is called the Eta, after the Greek letter symbolizing efficiency.
The Eta was first concieved of in 1996. The financiers founded Flugtechnik & Leichtbau to design the plane, no holds barred. Carbon fiber was chosen as the design material of choice. The design was modeled and tested in a wind tunnel August-December of 1996. At the end of 1997, the design was frozen, and plans for building a prototype begin.
The construction of this plane was full of difficulties, and even yielded some new construction methods. Construction of some parts independant of design changes begin in 1996. The a mockup was fully assembled in early 1998, and sacrificed to the stress test Gods. The plane passed 42,000 hours of simulated stress testing, making it certifiable for a life of 14,000 (one third) hours. This is 2,000 hours above the required minimum. Construction of a second wing for break testing was begin. In early/mid 1999, the model wing was completed. In mid 1999 it was static tested, and broke after forming a semi-circle. After they pick up all the carbon fiber shreds, they begin building a flyable prototype.
The prototype was finished in July of 2000. The plane passed its' ground vibration test during the month. On July 31, the plane flew for the first time. It was publically demonstrated the day after.
A new lighter fuselage was built in March of 2001, and construction of the second prototype was started.
Building and Design Charicteristics
This plane is full of new technologies and design characteristics. This plane uses an insane aspect ratio of 51.3 feet of wing length for every foot of width. This is about the limit of current fiber technology. Oddly, longitudal trim is adjusted by changing the angle of attack of the rear stabalizer. This is not often used in gliders. The wing also has a "chord skip". The wings widen suddenly about 3/4 of the way out. This allows for drag reduction while turning.
The plane uses many new manufacturing techniques. The wing spars were built as prepregs. The wing surface, being large and thick, was vacuuminjected. As far as safety goes, the cockpit is kevlar lined to prevent the carbon fiber from shattering in the event of a crash.
- Wing Span: 30.9m/101.38 feet
- Length: 9.84m/32.28 feet
- Height: not specified
- Maximum Weight: 920 Kg/2029.3 pounds
- Takeoff Weight: 850 Kg/1873.9 pounds (Depends on the glider-some were built heavier, and not within FAI rules for open class gliders. heavier gliders can still compete, but are not allowed water ballast.
- Empty Weight: UNKNOWN
- Wing Loading: 380 - 500 N/m2 7.93-10.44 lb/ft2
- Wing Area:18.6 m2/200.21 ft2
- Stall Speed:UNKNOWN
- Maximum Speed:UNKNOWN
- Engine:Solo 2625: 47 KW/64 HP
- G limits:UNKNOWN
- glide ratio: not officially released, but suspected to be in the range of 60-70 to 1, making it the highest performance sailplane ever.
- Production Volume: 6 hulls made as of 2004, one destroyed in testing, two totaled in crashes.
Sources: Fundamentals of Sailplane Design, http://www.leichtwerk.de/eta and atlas for composite info.
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