Sailplane - SpeedyLook encyclopedia

Principal components

Single-seaters or two-seaters, three essential parts are distinguished:

aerofoil: Its function is to ensure the bearing pressure of the machine. From 13 to 31 meters of Scale, it consists of two wings, so called feathers, which ensure the bearing pressure. Those have at their ends, on the trailing edge (left back the wing), of the ailerons of slope which control the axis of rolling.

Each wing is equipped with air-brakes which are devices whose function is to increase the rate of fall of the machine. The most powerful models also lay out of camber flaps, called sometimes high-lift devices , whose function is to increase the bearing pressure at low speed when they are directed into positive (downwards) and to decrease the trail if they are directed into negative (upwards) in high-speeds.

Research in aerodynamics made progress the technique and one nowadays finds devices of takeoff and sticking together of the boundary layer. You will be able to observe on surfaces of the profiles of tiny holes being used today for blowing (what allows the sticking together of the boundary layer) and which tomorrow will also be used for the aspiration of this boundary layer. These devices aim to improve the performances in all the flight envelope (minimum speed and maximum speed according to the angles of incidence).

the fuselage: Its function is to shelter the pilots and its connection with the empennage and the aerofoil ensures the control of the three axes; lace, rolling, pitching. This cylindroconic central part from 6 to 10 meters length receives with front, the cockpit and, in lower part, the landing gear. The fuselage also shelters, on the models with device of embarked takeoff, the engine and, in the majority of the cases, the pylon support of the propeller and/or the engine. The whole of this device is retractable in order to preserve at the machine all its aerodynamic qualities.

the empennage: Their function is to ensure the control of the axes of pitching and lace, and for the horizontal stabilizer, the stability of vol. They are made up, nowadays, of vertical plans and horizontal in “T” which carry the depth and rudders (rudder) also called stabilizer. Historically the empennage was also laid out in cross and “V”.

Instruments of flight and equipment

In 2003 in France the devices and the instruments of assistance to piloting requirements are the following:

the Anemometer or “airspeed indicator” in km/h;
the Altimeter in meters;
the variometer (measurement vertical speed) in m/s;
the compass;
the ball.

The complementary instruments are the following:

the radio;
the calculator of flight which integrates the principal following functions: altimeter, variometer, tachometer, géopositionnement by satellite, duration of flight, autonomy etc;
the wool yarn;
the Transponder on certain apparatuses.

To finish, the pilots generally have a Parachute. This one is obligatory in certain countries.

Essential parameters characterizing a sailplane

Its maximum smoothness, i.e., in calm air, the relationship between the horizontal distances and verticals which it can traverse. If he traverses 30 km for a loss of altitude of 1 000 meters (1 km), it has a smoothness of 30.

the smoothness max does not vary with the weight of the sailplane, only the speed to which this smoothness will be reached varies.
the smoothness of the sailplane varies with its horizontal speed; its smoothness is maximum for a determined weight, at a given horizontal speed.
This parameter is also trailed the bearing pressure ratio/(or top spin/drag L/D in English).

Its speed of maximum smoothness: this parameter is important when the sailplane must go up the wind (what slows down it compared to the ground and degrades its smoothness connect) by or although it crosses a zone of descents of which it may find it beneficial to leave quickly.

60 km/h for a sailplane of the years 1950
from 90 to 100 km/h for a current sailplane

Its polar speeds: it is the curve binding speeds horizontal (in X-coordinate) and vertical (in ordinate). The more “punt” it is, the more the sailplane preserves its smoothness when its speed increases. This curve mention the two parameters above (maximum smoothness and speed of smoothness maximum) but gives much better information on the total characteristics of the sailplane.

Its falling speed minimal, i.e. speed of descent lowest possible. The lower this speed is, the more quickly the sailplane will go up in ascents and will be able to exploit weak ascents.

Its minimal speed: more slowly it can fly, better it can exploit narrow ascents.

Its rate of Rolling, i.e. the maximum angular velocity which the pilot can order when it enters or leaves turn. An important rate of roll is useful to be able to exploit narrow and/or chopped ascents.

Its maximum speed not to be exceeded; this characteristic is of interest only under exceptional weather conditions when the ascents are frequent and powerful. It is crucial for the flights of record of distances and speeds.

Each type of sailplane is a compromise between these various parameters and other criteria like the facility of piloting, a healthy and homogeneous behavior on all the beach speed, the protection of the pilot in the event of accident, the facility of assembly and disassembling, its cost price, etc

Ballasting or Ballasting

Certain sailplanes are equipped with tanks enabling them to carry water for ballaster (to weigh down) the sailplane (water added with antifreeze if the flight is likely to be carried out under basic conditions temperature). The goal of this carrying of additional weight is to increase the speed of maximum smoothness. Indeed, the smoothness is maximum with a given angle of incidence. If the weight is more important, speed necessary to lift will be more important for this angle of incidence. To weigh down the sailplane thus makes it possible to shift polar speeds towards high speeds what is advantageous as well for speed in the competitions as to carry out connections in zones of descent or by wind of face.

The disadvantage is a falling speed minimal more important and obtained at a more important horizontal speed. it results from it a less good climbing speed and a difficulty increased to exploit narrow ascents.

Generally this ballast can be evacuated in vol. This for two reasons: especially in order to reduce the sailplane if the weather conditions are appropriate better for a not ballastée machine and to avoid landing with the ballast. The overweight could damage the machine in the event of hard landing. Moreover, the speed of approach would be more important and the increased take-off run what would be extremely unfavourable with a landing in shift.

The weight of ballast which a sailplane can carry varies:

LS-1D: 2 X 30 liters
Nimbus 4: 300 liters

Various types of sailplanes

Historically one can classify the various types of manufacture in the following way:

timber constructions and fabric (old);
mixed constructions of steel wood and tubes;
constructions all-metal (rare);
carbon or glass fiber constructions and resin (contemporary);
autonomous sailplanes with device of propulsion built-in and retractable, with an electrical motor or combustion engine more recently (like Antares);
the motoplaneurs whose device of propulsion is not retractable, are used as machine of school, towing or weather survey. Finer than the planes, and also much more sober, they offer a good compromise by combining the advantages of the one and other.

Various classes of sailplanes of competition

These categories are defined in chapter 7 of document FAI “Sporting Code Section 3 - Gliding”

Free class

No the rule.

Classify 15 meters

The only limitation is a maximum scale of 15 meters.

Classify 18 meters

The only limitation is a maximum scale of 18 meters.

Classify standard

Wings:

the scale cannot exceed 15 meters. All methods modifying the profile of the wing, others that the normal use of the ailerons, are prohibited. The elements increasing the bearing pressure are prohibited even if they are unusable.

Air-brakes:

the sailplane must be equipped with air-brakes which cannot be used to increase the performance. The brake chutes are prohibited.

Gear landing:

the landing gear can be fixed or retractable. The principal wheel must have at least 300 mm in diameter and 100 mm of width.

Ballast:

ballasting with water which can be evacuated in flight is authorized (ballasting).

Classify World

The sailplane of World class is the PW-5 whose design gained the competition of design of 1994. All the sailplanes must be built according to the specification of the IGC for the World class and must be in conformity with all the rules of the IGC. No modification allowed except those approved and is diffused in writing by the FAI towards all NAC with the account of the FAI.

Modification of the flow of air

Any modification modifying the flow of air around the sailplane is prohibited. That includes, but, is not limited to, the use of turbulateurs, careenages, surface treatment special. The only exceptions are:

a wool yarn;

a probe of total energy;

the adhesive band closing the hiatuses enters the fuselage and the wings, and between the fuselage and the tail. The closing of the hiatuses between surfaces of controls and the wings or depths are prohibited.

Switchgear

the electricals appliance and electronic is authorized, including for the instruments and the assistances with navigation.

Lest

the ballasts which can be evacuated in flight are prohibited. For a competition of World class, a mass must be specified by the director of the competition, between the maximum mass and the smallest possible mass for heaviest of the participants. To obtain this mass, each sailplane must incorporate a fixed ballast, approved by the IGC and which can include a ballast of tail.

Control of the center of gravity

All device able to modify, in flight, the position of the center of gravity of the sailplane is prohibited.

Classify Club

The goal of the class club is to preserve the value of old sailplanes of performance, by providing a cheap world championship and large quality, and to allow the pilots who do not have access to the sailplanes of the most standard of performance to take part in competitions with the more high level.

Inscription

the only limitation for the acceptance of a sailplane in a competition of class club is that it is in the beach of factors of handicap authorized for this competition.

Lest

ballasting with water is prohibited

Décompte of the points

a championship of class club must be with dimensions by using the formulas which take account of the handicaps

Classe Multi places 20 meters

Inscription

The class 20 m multi place takes again the sailplanes multi seats having a crew of two people. So handicaps are applied, then it must be in the beach of factor of handicaps authorized for this competition.

Équipage

the crew must be made up of two pilots who represent same NAC and have a license allotted consequently NAC. The gaining crew receives the title jointly.

Wings:

the scale cannot exceed 20 meters.

Ballast

ballasting with water which can be evacuated in flight is authorized.

Décompte of the points

a championship of class 20 meters multi-seat can be with dimensions by using the formulas which take account of handicap

List various sailplanes

Alexander Schleicher K8 : single-seater of semi drive lifting. Construction timber, fabric and tubes metal. First flight in 1957. Smoothness: 27 to 72 km/h; fall minimal: 0,65 m/s. More 1 000 specimens were manufactured. It is still extremely used as sailplane of approval, in local flight, and has excellent characteristics by small time.
ASK 13: sailplane wood and two-seater fabric dating from the Fifties. It is still often used for basic schooling.
Blanik L-13 and L-23: metal Czech two-seater sailplane. Popular in the USA.
ASK 21: two-seater plastic sailplane largely used for the school and the improvement. It is one of the rare sailplanes " certified Stunt-flying " according to the French aeronautical regulation.

Pilatus B4 : aluminum sailplane manufactured in the years 1970 and which was a strong success in Switzerland. Of a smoothness from approximately 35, it is " certified stunt-flying ".
Swift S1: Sailplane of Stunt-flying conceived for the stunt-flying.
Marianne C201B : two-seater plastic sailplane largely used for the school and the improvement. This sailplane with heavy piloting is the fruit of an ambitious French design: to produce a machine of competition accessible to the beginners. It is a sailplane of 18,55 meters scale, given for a maximum smoothness of 40.
PEGASE C101: single-seat plastic sailplane. It is one of the most widespread sailplanes of improvement in the club, even most widespread.
Twin Astir G103 : two-seater plastic sailplane largely used for the school and the improvement.
WA30 Bijave : sailplane wood and fabric have fuselage out of cloth-lined mesh wire. Old sailplane school (design années 1960) largely widespread in the small clubs as well as ASK 13. It gradually yields its place to the plastic sailplanes of school such as Alliance 34, ASK 21 or the twin Astir…
There also exists of many models of sailplanes been driven by an engine ( motoplaneurs ) with retractable propeller making it possible the sailplane to take off by its own means. Once desired altitude reached, the engine returns in the back beam of the fuselage of the sailplane. This type of sailplane is authorized in competitions if a recorder certifies that the engine was not given on the way during the épreuve !)
Lange Antares 20th motoplanor with electric propulsion.
two-seater Stemme S10-VT motoplanor in side by side with the engine positioned behind the pilots, and the propeller which is spread by advance of the nose cone.

Examples of sailplanes appearing in the classes

the class “Club”: old sailplanes having still honourable performances. Practically any machine of which handicaps it is known, can take part in compétions if its handicaps is in the beach retained for this contest. Certain sailplanes of appear in this class are also machines of class standard, race or free.

the Standard Cirrus of Schempp-Hirth;
LS1 C, D, F of Rolladen-Schneider;
the Makes out Glasflügel;
Centrair PEGASE.

the “standard” class: sailplanes of 15m maximum of scale without shutters.

Schempp-Hirth Discus and Discus 2;
Schleicher ASW 24;

the class “race”.

the family of the Ventus of Schempp-Hirth is in the class race (wing equipped with camber flaps).
the model ASG 29 of Alexander Schleicher.

the “free” class.

the Nimbus of Schempp-Hirth train a family of sailplanes of the large type feather.
ASH 25 of Alexander Schleicher GMBH & Co.
the Eta is currently the sailplane which presents largest Envergure to the world.

Some records

Which is the actual position of the technique?

The most powerful machines post today smoothnesses of 60 up to 70 for the last word (ETA) while the manufacturers more with the point of technology, ensure being technically able to produce today machines of smoothness 100 what remains still a mythical border: to traverse 100 kilometers for a loss of altitude of 1000 meters. Maybe, for one day of flight in plain in a zone of moderated climate, where the ceilings of about 2200 meters are frequent, a theoretical autonomy of 220 kilometers

Principal technologies employed

Sailplanes on takeoff with feet

They are aircraft controlled on three axes. They return in the category of the extra-light sailplanes. Takeoff is carried out while running on a slope, an auxiliary handle with brushes allowing the control of the rudder. Once the machine in flight, the pilot returns the legs in the careenage and uses a swing bar classique.
They are adapted to the flight of slope and the thermal flight. Their weak speed confers the possibility to them of exploiting small ascents. Certain models have diameters of spirals of 60 meters seulement.
The performances of some models are the following ones:

ULF 1 (1977): Smoothness from 16 to 55 km/h and a minimal fall of 0.8 m/s
Swift (2007): Smoothness from 27 to 75 km/h, VNE of 120 km/h and a minimal fall of 0.8 m/s
Archaeopteryx (2007): Smoothness 28 to 55 km/h, stalling speed from 30 to 35 km/h according to the wing load, VNE of 130 km/h and a minimal fall from 0.44 to 0.51 m/s according to the wing load

Experimental sailplanes

See also the sailplanes of the hang-glider type like Fauvel and its derivatives as Marske whose performances are, for the most powerful models, comparable with the traditional sailplanes of competition. They have some interesting characteristics: very good stability, very great solidity, bores unknown, very soft unhooking to see non-existent even in turn. There are nevertheless some small inconveniences: beach of centering reduced, almost impossible lift increasing, the action on the depth slows down definitely more the apparatus that a conventional sailplane.

Another type of hang-glider, the Swift, a light ultra sailplane on takeoff with feet or engine, whose sweptback wing (related with the Horten wings) is equipped with drifts with control surfaces of end of wings, its piloting being done on 3 axes on the last versions " light" (on 2 axes before).

Planes completing their flight while planing

Certain experimental or very specific planes complete their mission in planed flight. Although one can consider that this phase of flight makes it possible to classify them among the sailplanes or the motor bike sailplanes, it should be noted that they in common do not have almost anything with the sailplanes used for the gliding.

Among these machines, one can quote the Messerschmitt Me 163, the Bell X-S1, the X-15, the bearing Corps S and the Space shuttle.

These machines generally plane even less although conventional planes. They are practically “controllable stones”.

References

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