ETA Sailplane
See also: ETA
The sailplane ETA is a two-seater motoplanor whose scale is of 30,90 m of the class of competition known as " Libre". They are to date (2006) largest and more effective the sailplanes competition posting a smoothness 70 (for 1000 meters height lost; 70 km traversed).
It owes its name with the area of the technology where the Greek letter " eta" indicate the output.
It was to date built three specimens. In September 2003 the prototype specimen N° 2 was lost during a trial flight following a rupture of structure, the machine having been pushed out of its normal flight envelope, without damage for its two pilots who could eject and use their parachutes. Of course the machine was modified and in-flight tests were continued without problem.
The apparatus will be built into small série ; a production of three specimens per annum is programmed.
Quality of flight
Aerodynamic qualities of a sailplane are not measured only with the only value of the smoothness. The difference is also felt in the field of vol. the best angle of planed is reached at a specific speed which must be maintained precisely; what is seldom the case at the time of the practice. For this machine, no particular smoothness had been fixed, that Ci was given during in-flight tests and made it possible to leave polar speeds really measured. In practice, Eta makes the difference in low speeds, a little less in high speeds.
Characteristics
A sailplane of great scale undergoes important differentials speed applying to the wings at the time of the turns to strong slope. The consequences are notable on the drawing board and the result. The Eta has three sections of shutters by half-scale. at the time of the turns, the interior section is directed with 50° in positif ; the median section remains unchanged whereas the external section is clearly into negative. The gigantic scale requires also a particularly effective rudder.For this machine, a specific range of profiles was developed and tested in the vein low speed of the DNV of Brunswick.
The interior profile (in medium of wing) HQR 1 drift of the profile tested HQ 17 particularly efficient in large the speed of the field of vol.
The external profile (in end of wing) HQR 2 fact proof of a better bearing pressure than the HQR profile; 1 and still contributes to the effectiveness of the geometry of the wing. Contrary to the conventional ailerons, the suction face preserves a laminar flow even at the great incidences, without loss of effectiveness to the ailerons.
In the zone of the root, the HQR profile; 3 was especially studied to counter the turbulences met by employing a relative thickness of 16,45 %.
Thanks to its largely dimensioned surface, the rudder benefits from a HQR profile; 4 whose aerodynamic resistance was decreased.
The HQR profile; 5 of the elevator was calculated so that, even when the ordering of trim is in opposed position, the piloting of the machine remains effective.
Weblinks
Official page of Eta-Aircraft
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