GlasflŸgel H-206 Hornet (WL)

 

INTRODUCTION

The H-206 Hornet is the successor of the well-known Std-Libelle and was built between 1974 and 1979 in the former GlasflŸgel Factory. It has the same wings as the Club-Libelle which is also the same as the Std-Libelle, except that the later has more usual airbrakes compared to the trailing edge system for the Club-Libelle and the Hornet. The fuselage rear part is the same as the Club-Libelle; the front part of the fuselage is new designed. The fuselage was later copied for the Mosquito and the 304, which is now still in production at the HPH factory. A total of 102 Hornets have been built plus about 30 Hornet-C featuring carbon fiber wings and a single piece front hinged canopy, like the later Mosquito.

 

THE GLIDER

Like all the gliders of the GlasflŸgel Company, the design was very advanced:

-       In flight adjustable pedals and backrest

-       Automatic connection of all controls, this system invented by GlasflŸgel, is still used by all Schemp-Hirth sailplanes, and partly in other types.

-       Automatic water ballast system connection, water dump at fuselage bottom.

-       Control surface actuator arms are built in, so the glider has no extruding actuator covers.

-       Parallelogram elevator stick with automatic trim system

 

The wings have a double tapered form with an area of 9.8m²; the wing profile is a Wortmann FX 66-17AII-182, whatever that means. The wings are a glass fiber reinforced plastic construction (carbon fiber for the C-model), it has water tanks (no bags!) of 2x 40l. Compared to the two Libelle gliders, the Hornet wing was reinforced to accommodate the extra water ballast. The lack of Schemp-Hirth type airbrakes and the built in actuator arms make the wing very smooth and streamlined.

 

The fuselage has also built in actuator arms for the rudder and the elevator; it features a big, 5.00 x 5 main wheel that gives good ground clearance. Standard equipped includes a tail wheel and two Tost-hooks. The nose hook is actually situated at the nose which is very safe and easy for air-tows. The hornet has a two piece canopy, except for Hornet-C. The front part is fixed and the rear part tilts backwards (as in early Jantars and DG100). This cockpit mechanism is the only thing on the plane that is GlasflŸgel unworthy. Eugen HŠnle probably thought the same and replaced it with a single piece, front tilting canopy on Hornet-C, Mosquito and an improved version on the H-304. The cockpit is full of space, and the luggage compartment is also very big. For works on the instrument panel, the front piece of the canopy and can easily be removed by unscrewing some bolts.

 

THE AIRBRAKES

An eye-catcher on the Hornet is the airbrakes, or should we say dive-brakes. At that time, designers were looking for solutions to minimize the drag caused by the airbrakes. First step was the top only airbrake to prevent pressure loss through the wing. Some designs of that time show conventional airbrakes that are placed at the rear part of the wing, where the airflow is already turbulent, some designs show no airbrakes at all (ASW12 and original PIK20). The Hornet has trailing edge airbrakes which deploy about 1/3 above the wing and 2/3 on the underside. It is a brake-only system; there is no possibility to use the lower part separately as a flap like on the (mini-)Nimbus, Ventus, H-303 and 304.

 

This kind of non-conventional airbrakes has its advantages and difficulties, but once you know the system it is far from dangerous. What not to do is come on approach with full airbrakes near stall speed and than suddenly close the airbrakes. Because the stall speed with airbrakes is some 3 to 4 km/h lower than the normal stall speed, this can cause the plane to stall close to the ground. Another difficulty is landing the plane. The glider tends to float on ground effect; a fully held-off landing is not easy and it takes some training to make spot landings. If not fully held of on short grass, the glider can jump up again. In that case, leave the airbrakes where they are and just wait, it will go down again. However, one can never feel more comfortable for on out-landing than with these trailing edge dive brakes. The approach angle decreases to 1/3 with full airbrakes and when you hit rough surface, the glider doesnÕt tempt to bump up again. So no problems with the ground effect any more, just put it on the ground. Fully extended and with the nose pointed 80¡ down, this glider does not go faster than 170km/h (make sure everything is fixed in the luggage compartment behind the headrest). The airbrakes can be opened at max speed (250km/h); people who actually did it, donÕt recommend it however. Once you get to know the airbrakes, you will enjoy it.

 

RIGGING THE GLIDER

This glider is a dream to rig. Wings are of standard weight for a 15m plane, controls hook up automatic, a rigging aid is used to pull the wings together (same as Libelle, PIK20). It uses a fork tongue system where the wing root end pins fit into the other wings root rib when pulled together. A small central bolt is easily put in to secure that the wings donÕt separate. The tailplane is very light and uses a Schemp-Hirth system to install (actually the SH-system is a GlasflŸgel system, but since more people know the Schemp-Hirth planesÉ). The winglets are pushed in and locked with a spring pin in a hole at the top surface of the wing. Two trained persons clear the job in 10 minutes. Taping the plane is somewhat difficult at the leading edge of the wing to the fuselage, but a great improvement compared to the Std-Libelle.

 

FLIGHT HANDLING - CHARACTERISTICS

The Hornet has an empty weight that is about 250kg (50kg more than a Std-Libelle). The climbing characteristics are therefore comparable to a fully ballasted Libelle. With this high empty weight and the low wing area of 9.8m², the Hornet is flown at 33 to 34 kg/m² in unballasted configuration, which is quiet high for a club class glider. Together with the aerodynamic design, it makes the glider a fast competitor in club class competitions. With additional 80l water ballast, wing loadings up to 43kg/m² can be obtained. I never fly it fully ballasted. I prefer a 40l configuration for normal XC-conditions and 60l for strong weather (in Belgium!).

 

The rudder-aileron coordination of the Hornet is much improved compared to the Libelle (which rudder?). All controls are very light to use, including the landing gear lever. At low speeds, the ailerons seem a little underpowered. However, during take off and landing, the ailerons give sufficient control. The Hornet never drops a wing.

 

In smooth thermals, at the end of the day, you can thermal close to stall speed without any difficulties and the plane climbs as good as any other. However, the glider was not very stable in turbulent thermals and should be flown at higher speeds than other club class gliders, which makes him a difficult climber. The plane has to be flown very accurately if you want to perform well in a thermal. I found great handling and climbing improvement with the winglets which we retrofitted after 2 years. Like the Libelle, the wing profile is not very sensitive to bugs and rain.

 

The advantage of this glider is at high speeds. It has a very flat polar that out-flies a Pegase as from 140km/h and tends even towards an LS4, DG300 and Discus at speeds above 160km/h. The lower handicap of 100 makes this plane very hard to beat on fast days and final glides; and the parallelogram stick assures a very smooth ride when flying fast in turbulent weather. In the club class the glider is comparable to ASW19 and LS1f. Glide ratio is claimed 38 at 105km/h and I once read a test flight report a Hornet WL in England that showed an improved L/D of 40. I never fly in perfect laminar conditions so I wouldnÕt know if this is true, but I think the main advantage of the winglets lies in the improved stability and climbing characteristics.

 

Stall is completely harmless; I never sensed any intention of a wing drop. However, when flying in turbulent, rough thermals without winglets, one could get the impression that the wing sometimes drops when flying to slow.

 

MAINTENANCE

GlasflŸgel quitted the sailplane business in early eighties. People say that Eugen HŠnle was a better plane builder than business man. Hansjšrg Streifeneder, a former employee of the GlasflŸgel Company, started his own sailplane service and repair shop in Grabenstetten and continues offering service and maintenance on all GlasflŸgel planes. He also made it possible to get an official approval for the winglet retrofitting on both Libelles and the Hornet.

 

TECHNICAL INFO (from Wikipedia)

Constructor

Eugen HŠnle

First Flight

21. December 1974

Wing span

15,00 m

Wing surface

9,80 m2

Aspect Ratio

23

Length

6,40 m

Structure

GRP

Empty weight

245 kg

Max loading

180 kg

Max weight

420 kg

Wing loading

32 to 42,86 kg/m2

Vmin

65 km/h

Vne

250 km/h

Vmax Winch

110 km/h

Vmax Tow

150 km/h

Minimum Sinkspeed

0,60 m/s @ 74 km/h

L/D

1:38 @ 103 km/h

Profile

Wortmann FX 66-17AII-182

 

 

ý¬§©ª«£«¥¬Š¬§¬š¬

Before winglet retrofit

 

With the winglets

ý¬§©ª«£«¥¬Š¬§¬š¬

At start grid Ð shows the cockpit system