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Schempp-Hirth Ventus / Lentus

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Ventus

 

The 15-meter Ventus (Latin for 'wind') designed by Holighaus, Schott, Treiber and Schuo, (not to be confused with the later completely redesigned Ventus 2) has all-carbon fiber wings. The Ventus high performance single-seater is the first of a new generation of racing and competition 15m Class sailplanes featuring carbon-fibre in their structures; the mid-set wings are specially designed to take full advantage of this material's lightness and extra stiffness. The strength of this material permitted use of a very thin and more laminar airfoil developed by F.X. Wortmann, Dieter Althaus and Ventus designer Klaus Holighaus, thinner than previous Wortmann profiles. The stiffness of carbon fiber prevents wing twist at high speeds such as often occurs with fiberglass. A special characteristic of this new section is that at low-drag speeds, stall warning buffeting occurs when the angle of attack must increase over 10° before the stall itself actually occurs, this giving a previously unknown safety margin in narrow thermals, in ridge or mountain flying and in landing. The wing and its skin are made entirely of carbon-fibre, which gives increased torsional stiffness and reduces by over two-thirds the negative tip twist experienced with thin glassfibre wings, and the resulting lift penalties; the wing skin is made of specially developed extrafine-weave carbon cloth, and has high stiffness to maintain the wing profile.
 
The same new air brake/flap system as on the Nimbus 2C is featured, the air brakes being behind the 70% chord line outside the wing's laminar flow area, and this system gives an unusually short and slow landing. The two-piece ailerons feature Grob elastic flap-type joints on the lower wing surfaces to make the aileron/wing joint gapless and reduce drag, while enabling the upper surface gap to be kept very small. Tail surfaces are similar to those of the Nimbus, with a fixed incidence tailplane and elevator.
The prototype Ventus first flew on 3 May 1980 and was offered with an A model for shorter pilots, and a slightly wider and longer B model. There are two fuselage sizes, the normal version (the Ventus B) being big enough for pilots from 5ft 9in to 6ft 5in tall, this fuselage being 24.75in wide, 32.75in high and 21ft 4.47in long. The smaller fuselage (the Ventus A) is designed so that pilots up to 5ft 9in tall will not feel 'lost' in a cockpit designed to accommodate six-footers, and is 21.25in wide x 29.5 in high x 20ft 9.5 in long; its smaller size results in a slight performance bonus.
 
In both versions the pilot sits under a one-piece sideways-hinging cockpit canopy which is easily jettisonable; the canopy frame is of carbon-fibre and there is provision for a variety of instrumentation. Both fuselage sizes have a steel mid-fuselage frame on which is mounted the retractable monowheel, the flap and aileron drives and the wing lift-pin sockets; this frame takes the stresses from the landing gear directly through to the wings, and there is also a tail bumper fairing under the fin. The rudder sizes are slightly different for each fuselage size, and there is provision for over 330lb of water ballast in integral fuselage tanks.The Ventus has trailing-edge combination flaps and dive brakes, and aileron control mixers which reduce aileron deflection when extreme positve or negative flap is selected.
 
The B model had optional 16.6 m. tip extensions, while the C model offered 15 m winglets tip extensions increasing the span to 16.6 or 17.6 m, and a 5 kg /11 lb fin ballast tank. Dick Johnson tested a modified Ventus A with 16.5 m. tip extensions to give a demonstrated best L/D of 50 at 78 kph/ 42 kt/ 48 mph and a minimum sink rate of 0.43 m/s/ 1.42 fps/ 0.84 kt.

 

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Ventus B/16.6


The sustainer Ventus bT had 16.6 m wings and a retractable 15 kW/ 20 bhp Oehler Solo turbo engine.

Constant refinement was also the key for the success of the Racing Class glider Ventus which debuted in spring 1986 as the model Ventus-c (on request with wing tip extensions for 17,6 m wingspan). Production of this model was ceased in 1994 after over 600 examples were produced (including self launchers and turbos).

The cT had 17.6 m wings and a Solo engine uprated to 22 kW/ 30 bhp.

A Ventus won the 15 m class at the 1983 World Championships at Hobbs, NM, and others took 10 of the first 15 places. R.L. Robertson of Great Britain, along with others, won the world triangle distance record of 1,363 km./ 846.9 miles in 1986 in a Ventus A.

The Ventus 2, despite its names, is substantially changed from its similarly named predecessor. It has a complely new Discus planform wing and comes in a number of different configurations.

The unpowered sailplane comes in three different varieties, the short fuselage 15 m Ventus 2a, the larger fuselage 15 m -2b, and the convertible tip 2c (which has the larger -2b fuselage) with a choice of 15 m or 18 m outer wing panels.

On the 31.03.94, the first flight of the “new Ventus generation’ took to the air. A concept still realized by Klaus Holighaus and advanced with energy, but he however could not bring to conclusion as he lost his life in a flight accident on the 09.08.1994.

He had still flown the variants Ventus-2a and Ventus-2b and had also witnessed the double victory of the Ventus-2 at the European Championships in Rieti in 1994 as a testament to his wing shape concepts.  
His last design also followed on to win the World Championships in New Zealand as well as in France in 1997.
The 18m version of the Ventus-2 which was designed by Klaus Holighaus was first flown on the 30th March 1995 by his son Tilo for the time. It is produced as the Ventus-2c, as the Ventus-2cT with the “Turbo” and as the self launcher Ventus-2cM.

The sustainer engined 2cT comes with 18 m span, while the self-launching 2cM has the 15 m or 18 m wingtip option with an empty weight of approximately 350 kg / 772 lb. The liquid cooled Solo engine remains in the fuselage when the mast mounted propeller is raised. This has folding blades which reduce the size of the cutout required in the fuselage to accommodate the mast. As a flapped sailplane, the 15 m versions comply with 15 m racing class at the 1995 World Championships at Omarama, New Zealand.

Until spring 1998, 100 examples were delivered. As of the summer of 1998, the self launcher was being produced with an even more powerful SOLO engine.

The World Championships were successful in Mafeking 2001, with a renewed title for the Ventus-2ax in the 15m class, a variant sporting a drag reduced tail section and Maughmer winglets. These modifications (which improved the flight characteristics at lower speeds and higher wing loadings) were carried through to the Ventus2-bx, along with a newly designed outer contour and cockpit area shape.

The Ventus-2cT won the 18m class at the FAI World Air Games in Lillo/Spain. Mid May 2002 saw the delivery of the first ballistic chute “total recovery system“ fitted to a Ventus-2bxR which was designed by the neighbouring company Glasfaser-Flugzeug-Service GmbH in Grabenstetten and tested in a Discus. 2002 saw the delivery of the 1000th Discus (all variants) as well as the completion of the 1000th Ventus (all variants).

In 2003 a fire broke out in one of the buildings delaying production by several months. Affected were the fuselage moulds for the new Ventus-2cxT (a structurally strengthened version with optimised tail unit, improved outer wings and Maughmer winglets for increased roll rate at even higher wing loadings). These changes, including strengthening in the cockpit area, have been incorporated into the Ventus-2cx glider and the motorglider Ventus-2cxM as standard equipment and have the title of “New Ventus Generation“.

The European Gliding Championships in Lithuania 2004 confirmed the performance of the new Schempp-Hirth aircraft, with the the double win of the Ventus-2cx, and in the racing class with the bronze title from Axel Horn in a Ventus-2ax (behind two Ventus-2a).

 

A one-off sailplane known as the Lentus, which consists of a Ventus A fuselage fitted with Nimbus C wings, was used for performance comparison trials with the Ventus.

 

Ventus
Wing span: 15m / 49.2ft
Wing area: 9.51sq.m / 102.4sq.ft
Aspect ratio: 23.7
Length: 21.4 ft
Height: 2.7 ft
Empty Weight: 235kg / 518lb
Payload: 190kg / 639lb
Gross Weight: 525kg / 1157lb
Wing Load: 55.2kg/sq.m / 11.31lb/sq.ft
Water Ballast: 150kg / 331lb
Max speed: 135 kt
Stalling speed: 42 kt
L/DMax: 44 at 100 kph / 54 kt / 62 mph
MinSink: 0.58 m/s / 1.90 fps / 1.13 kt / 130 fpm at 58 kt
Airfoil: Wortmann/Holighaus/Althaus
Seats: 1

Ventus a
Wing span: 16.6m

 

Ventus a
Span: 49 ft 2.5 in
Length: 20 ft 9.5 in
Wing area: 102.4 sqft
Aspect ratio: 23.7
Empty weight: 474 lb
Max weight: 949 lb
Max speed: 155 mph
Min sinking speed: 2.17 ft/sec at 9.2 lb/sq ft wing loading
Best glide ratio: 44:1 at 74.6 mph

 

Ventus b
Span 15 m / 49 ft 2.5 in
Wing area 9.51 sq.m / 102.4 sqft
Aspect ratio 23,7
Fuselage length 6.58 m / 21 ft 4.75 in
Unloaded weight approx. 225 kg / 486 lb
Gross weight 525 kg / 949 lb
Wing loading 31,5-55,2 kg/sq.m
Water ballast 168 lt
Maximum speed: 250 km/h / 155 mph
Maneuver speed 200 km/h
Min sink: 0.58 m/s / 2.17 ft/sec at 9.2 lb/sq ft wing loading
Best glide ratio: 44:1 at 74.6 mph


Ventus b/16.6
Wing span: 16,5m

Ventus bT
Wingspan: 15/17,6m

Ventus 2A
Wing span: 15m / 49.2ft
Wing area: 9.67sq.m / 104.41sq.ft
Aspect ratio: 23.3
Airfoil: Boermans DU 93-132/15
Empty Weight: 225kg / 496lb
Payload: 300kg / 661lb
Gross Weight: 525kg / 1157lb
Wing Load: 54kg/sq.m / 11.1lb/sq.ft
Water Ballast: 200kg / 441lb
L/DMax: 46 93 kph / 50 kt / 58 mph
MinSink: 0.60 m/s / 1.96 fps / 1.16 kt
Seats: 1

Ventus 2C
Wing span: 18m / 59ft
Wing area: 11sq.m / 118.4sq.ft
Aspect ratio: 29.4
Airfoil: Boermans DU 93-132/15
Empty Weight: 265kg / 562lb
Payload: 270kg / 595lb
Gross Weight: 525kg / 1157lb
Wing Load: 47.73kg/sq.m / 9.77lb/sq.ft
Water Ballast: 200kg / 441lb
L/DMax: 46 93 kph / 50 kt / 58 mph
MinSink: 0.60 m/s / 1.96 fps / 1.16 kt
Seats: 1

Ventus cT
Wing span: 15/17.6m

Ventus cM
Wingspan: 15/17,6m

 

 


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