Flight and Operations Manual for the Sailplane Model ASW20

his instruction time that the minimum speed goes up in steep turns or when loading the aircraft with ballast ( fuel, flight instructor ). In conformity to the same law as the minimum speed the speed ranges of the single flap settings do also shift by changement of the wing loading and/or the load factor. The following table will show to you the coherencies. The data stated are based on performance measurements. 8 A S W 2 0 - Flight Manual 8a A S W 2 0 - Flight Manual Now these above-mentioned coherencies should not confound the ASW 20-pilot nor make him give up because it is too complicated. There is a very simple method of estimating the correct flight attitude. The flap has been designed such that the change in angle of attack produced by flap deflection just compensates for the difference in angle of attack which results from the new flight attitude. This means that the fuselage and tailplane always remain almost parallel to the airflow. Since the glide angle is very flat for the whole speed range of the ASW 20, the relation of the ship to the horizon remains the same for load factor 1 ( 1g ) provided that the flaps are used properly, A simple pitch indicator will move only in a small range, even in turns and other accelerated manoeuvres, and, therefore, is a good control instrument for the low drag angle of attack. ( This is, however, not true for flap Position 5 or for extended air brakes because in this case you are intentionally leaving the aerodynamically optimum ranges in order to produce more drag ). The table also shows the control actions for some flight manoeuvres. Principally, a flapped glider has two pitch controls : flaps and elevator. However, only one combination of both control settings results in optimum performance for a given flight attitude. 9 A S W 2 0 - Flight Manual Case 1 Acceleration from thermalling to fast cruise : According to the law that energy remains constant we can only pick up speed ( kinetic energy ) by giving away altitude ( potential or static energy) with regard to the air around us. This is only possible by reducing our g-load ( or load factor , below 1. For thermalling our speed was 85 km/h and n = 1.3 (because of 40° bank ) in flap position 4. Now we want to accelerate downwards ( n = 0.5 ) and, pursuant to our table, therefore simultaneously must reduce bank and put the lever at least into No. 3 position, but as soon as our speed exceeds 92 km/h we must even put the flap lever into position No.2. If we now do not do anything else, the static stability of the sailplane will balance out at approximately 130 to 160.km/h and load factor 1. If we want to fly faster, we have to set flap position No.1. The stick shows only little movement during the whole manoeuvre which manifest itself also by the fact that the trim hardly needs to be adjusted. With a conventional rigid profile wing the whole trim range would be needed for such a manoeuvre. Case 2 Pull-up into a thermal from very high speed ( wing loading 3 kp/m 2 ) : From fast cruise of 200 km/h ( 1g ) a pull-up into a thermal shall be done. This is impossible without increasing the load factor. Since turbulence is to be expected, a mild 1.3 g – pull-up should be initiated. Looking at our table we find that flap position 1 still should be set for load factor 1.3 and 200 km/h. 10 A S W 2 0 - Flight Manual The pull-up is initiated by slightly pulling the stick. At about 183 km/h flap position 2 is set. The sailplane meanwhile climbs so rapidly that no further pulling is necessary and a straight climb at load factor 1 is following. Flap position 2 can be maintained down to 130 km/h, then flap position 3 is set. To finish the climb, we are shortly setting flap position 2 which is reducing the load factor to about 0.5, then bank is applied and simultaneously the flap lever is shifted to position 4. The stick position is again the same during the whole manoeuvre and the trim needs only slight adjustment. In a flapped sailplane the flap handle is the more active pitch control whereas the stick is more or less a correcting control. The flap handle directly controls the wing lift and is, therefore, much more sensitive than a conventional elevator which through rotation of the aircraft changes the angle of attack, and thus relatively slowly changes the lift. At high speed flight of above approximately 180 km/h the pitch is merely controlled by elevator movement, since flap position 1 covers more than the angle of attack range which is necessary. For low altitude flights ( approach, slope soaring, finish gate low passes ) and when thermalling together with other sailplanes you absolutely have to leave off the operation of the flap handle because of the sudden altitude changes which are hardly to calculate. 11 A S W 2 0 - Flight Manual 1.2. Operating Handles, Placards and Nomenclatures Stick with wheel-brake lever and transmitter button ( optional ). Rudder pedal with longitudinal adjustment. Rudder pedal adjustment : grey knob RH of control stick To move pedals back : Take load off pedals and pull back. Release control knob suddenly and put slight pressure on pedals to adjust them. To move pedals forward : Pull knob and simultaneously push pedals forward. Release control knob suddenly and lock in place by putting slight pressure on pedals. Flap control : Black lever on upper LH cockpit wall. Marking of the essential flap positions by numbers 1, 2, 3, 4, and 5 below the flap lever. Flap lever in high position Flap lever in landing position Air brakes (spoilers) Blue lever on LH cockpit wall. Extending of air brakes by pulling lever backwards. 12 A S W 2 0 - Flight Manual Trim noseheavy: press together the green trim knob (left cockpit wall) and push forwards. Trim tailheavy: press together the green trim knob and push back- wards. Landing gear retracted : Black handle on lower LH cockpit wall pulled back. Landing gear extended Tow release : Yellow knob LH of stick Open canopy : Move white knobs LH and RH on upper side of canopy frame forward. To jettison canopy: Pull red handle above instrument panel; the normal canopy locking mechanism must be opened before !!! 13 A S W 2 0 - Flight Manual Ventilation : Light blue knob above LH area of instrument panel. Knob pulled = Open Additional ventilation : Intake in sliding window Water ballast : Dark blue lever LH and RE on upper cockpit wall. To open valve move lever forward. Note : LH lever for left wing tank, RH lever for right wing tank. Anchoring point for parachute static line : Red ring on main bulkhead 14 A S W 2 0 - Flight Manual Serial number and Type Plate: A . Schleicher 6416 Poppenhausen AS - W 20 20 XXX Made in West Germany Muster : Werk Nr. Kennz : loading of baggage compartment Loading of baggage max. Compartment 15kp [33lb] Data Placard and loading scheme: Segleflugzeugbau A. Schleicher Poppenhausen Type: S. No. Data plate Permission For: Winch Launch Aero tow Max. speed Maneuvering speed 1 up to up to up to Max. speed for flap pos. Max. speed for flap pos. Max. speed for flap pos. Max. speed for flap pos. Max. speed for flap pos. Gear down up to 2 3 4 5 Weight and Balance single dual max. min. Max. permisible all up weight up to 15 A S W 2 0 - Flight Manual 1.3. Operation Values and Limitations Maximum indicated airspeeds ( equivalent airspeeds are about 5 % higher, see page 49 ) ( below 3000 a m.s.l. / 9000 feet m.s.l.* ) For flap position 1 For flap position 2 For flap Position 3 For flap position 4 For flap position 5 (lan- In rough air ** With full control deflec- tions (manoeuvre speed) For winch and auto tow For aerotow For extending landing gear 265 km/h 200 km/h 200 km/h 160 km/h 120 km/h 180 km/h 175 km/h 120 km/h 175 km/h 175 km/h 143 knots 108 knots 108 knots 86 knots 65 knots 97 knots 94 knots 65 knots 94 knots 94 knots For this purpose the following coloured calibration markings appear on the airspeed indicator : Red line at Green range between Yellow range between White range between White marking WK5 at WK4 at WK2 & 3 at km/h 265 90 - 180 180 - 265 85 – 200 120 160 200 Knots 143 48,5 – 97 97 - 143 46 – 108 65 86 108 The yellow at 90 km/h shows the recommended approach speed for landing. * Please note : The in-flight flutter tests are done at about 2,500 m to 3,500 m m.s.l. Since the airspeed indicator reads too low values 16 A S W 2 0 - Flight Manual at increasing altitude, the critical flutter speed , however, is more or less determined by true airspeed for light aircraft, the following speed limits are valid for high altitude flights Altitude Max. Speed (indicated) meter m.s.l. feet m.s.l km/h Knots 0-3,000 5,000 7,000 9,000 11,000 13,000 0-10.000 16,400 23,00 29,500 36,000 42,600 265 240 215 195 170 145 143 130 115 105 92 78 If the above limited values are not exceeded, the true airspeed will be constantly 315 km/h above 3000 m / 10000 feet m.s.l. and thus is high enough to face the strongest wind in wave flight. ** Please note : Rough air, according to airworthiness requirements, is turbulence found in wave rotors, thunderstorm clouds, dust devils and when skimming mountain crests. An experienced pilot will know that he must be aware of even stronger turbulence in thunderstorms or in alpine regions. Weights ( masses ) Empty weight with min. equipment ~ 255kg / 565lbs. Max. all-up weight 454kg / 1000lbs. Max. weight of non lift producing 235kg/ 518lbs. Components. Permissible water ballast max. 120kg / 265lbs ( depending on cockpit load ) or 32 USGals. See table on page 20. 17 A S W 2 0 - Flight Manual Weak link in towing line 600 kg ( 1320 lbs ) for auto / winch and aerotow In Flight Centre of Gravity Datum point is the leading edge of the wing root rib ( without the fillet of the wing - fuselage fairing ). The horizontal reference line is the centre line of the fuselage tail cone or a 1000 : 45 wedge template levelled out on the top side of the fuselage aft portion (see the page "Rigging Data" in the appendix). In flight centre of gravity range is from 240 mm ( 9.45 inch ) to 360 mm ( 14,17 inch ) behind datum. Cloud flying The sailplane is suited for cloud flying. Flights under icing conditions are not recommended, specially if the glider has been wet before climbing through the icing level. Experiences have shown that in the area of the rather narrow control gaps, any rain or condensation drops dry off relatively slowly and turn to ice when climbing above the freezing level. Therefore, one has to face a stiffening of the controls, leading to blocked controls in extreme cases. Isolated climbs above the freezing level with a dry sailplane did not lead to any stiffening of the controls, even though the leading edges of wings and control surfaces showed severe icing. Flights with water ballast above freezing level should be avoided because of the risk of icing-up of the tank ventilation. 18 A S W 2 0 - Flight Manual There fore o ne has to face stiffening of the cont ro ls which is le ading to blocked controls in extr eme ca ses. After one c limb above the freezing level wit h a dr y sailp lane n o stiffening of the controls is t o be e xpec te d even if t he leading edges of wings and c ontr ol s ur face s show seve re icing With wate r ballast flights above freezin g le vel sh ould b e avoid ed b ec ause of the risk of icing-up of t he t an k venti lati on Aerobatics The 1 6,59 m span version of the ASW 20 L . is no t ap pr oved for a erob at ics. For aerobatic manoeuvres wit h th e 15 m span vers io n see page 32. Seati ng p os ition: 1. Do no t us e soft seat or back cushion s wh ich are th ick er t han 2 cm. 2. Th e b ackr est must be adjusted such t hat the pilo t is se ate d wi th his head just below the cano py a nd a s far fo rwa rd a s possible. When the stick is i n th e no rm al po sit ion (trim 10 mm off the front e dge of t he s lo tted ga te) , th e upper arm should rest aga inst the bod y wh ile the elbow rests an the upper t high . Su ch a co mfo rtab le seating position is prev enti ve a gain st PIO (p ilo t in duced oscillations). Extre me P il ot Sizes Tall pilo ts may fly without the adjustab le s eat re st, howev er, th ey have to use a stiff cushio n th at l ev els th e edge of t he tow hook fairing and the box of the wh eel. Prior to th e first start the sailplane m ust be p ut . on stand s an d - with a pilot sitting in the coc kpit - it ha s to be che ck ed that the parachute does no t pr ess so har d again st t he cockpit rear wall that the l andi ng g ea r ca n only be p ul led up by severe forces. If t his is t he cas e, the r ear wa ll must be reinforced by a pi ece of w oo d fr om the o utsi de . Tall pilo ts should also use gym shoes wi th h eels a s lo w as po ssib le so that they can use the mos t fo rwar d peda l posit ion. S mall pilots should check prio r to sta rt if they can ap ply full rudder deflections a nd i f th ey can no t fall off th e pedals with their feet. If nece ssar y, a board wit h a support for the heels can b e in stal le d on the p edal s. Do not use soft (lead or sand) seat cushions. We recommend to use only trim weights in the fuselage nose and seat cushions made from a foam which cannot be compressed (Styrofoam, Conticeil or safety foam like Dunlopillo etc.). T N n o . 3 0 0 1 . 0 4 . 8 7 19 A S W 2 0 - Flight Manual Limit Load Factors 16,59m 15,00m 165km/h 89kn. 175km/h 94kn. Span Max. positive load factor + 5.3 Max. negative load factor - 2.65 Reducing proportionally with airspeed to Max. positive load factor + 4.0 Max. negative load factor - 1.5 250km/h 135kn. 265km/h 143kn. 1.4. Weight and Balance Information Payload in cockpit ( pilot plus parachute ) : minimum 70 kg ( 154 lbs ) maximum 115 kg ( 253 lbs ) For possible exceptions see page 31 If the useful load is below the minimum, the shortfall below the minimum payload must be made good by the addition of trim weights in the fuselage nose (this is available as an optional extra, see page 22). We recommend that inexperienced pilots and/or pilots who fly this model for the first time, do not make their first flights with the rearmost C.G. position, i.e. they should not go for a just still acceptable minimum payload, but should stay approx. 10 - 15 kg above the minimum useful load in the pilot seat. Light pilots should fix about 4 trim discs more than the actually required minimum. Loading of Water Ballast (only for 15 m span version) The maximum all up flying weight of 454 kg (1000 lbs.) must not be exceeded. For the determination of the proper amount of water ballast the following table may be used : 20 A S W 2 0 - Flight Manual The loading of the baggage compartment has no significant effect on the CG location. It must not, however, be loaded by more than 15 kg ( 331 lbs ). Hard objects weighing more than 1 kg ( 2.21 lbs ) should be carefully secured in the baggage area in order to prevent accidents. Loading of Water Ballast : The maximum all up flying weight of 454 kg (1000 lbs.) must not be exceeded. For the determination of the proper amount of water ballast the following table may be used : 20a A S W 2 0 - Flight Manual As an option the ASW 20 can be equipped with a pin in front of the rudder pedals which allows the installation of interchangeable trim weights. These trim weights are recommended if the sailplane is flown by several pilots of more than 20 kg ( 45 lbs. ) difference in weight. By the installation of a permanent lead trim weigh in the tail above the tail skid the glider is trimmed in such a way that the heaviest pilot gets an in flight C, of G. of about 0,3 m behind datum. This is causing, of course, an increase of the minimum permissible cockpit payload so that a light-weight pilot cannot fly the sailplane without additional ballast. In order to avoid the taking along of heavy and unwieldy lead cushions a light-weight pilot shall install trim-discs at the bolt in front of the pedals The lead discs weigh 1 kg ( 2.2 lbs. ) each. Since the weights are installed so far forward in the sailplane, they have 2.5 times the effectivity. 20b A S W 2 0 - Flight Manual of the same mass in the seat. If 1 kg is installed in front of the pedals, the minimum cockpit payload is by 2.5 kg ( 5.51 lbs.) lower; if 2 kg ( 4.4 lbs.) are installed, the payload is by 5 kg ( 11.02 lbs.) lower, and so on Remark ( Important ! ) : 1. Only 7 weights, i.e. 7 kg, are allowed to be installed at the fittings. 2. The nut must be properly fixed and checked for every take - off. It must be safetied with a safety pin. 3. If the minimum cockpit payload trimmed by the ballast weights is exceeded by more than 30kg ( 66 lbs.), i.e. if a heavier pilot wants to fly again, the trim weights have to be removed. The inner cockpit wall at the right hand side must show the following placard : Minimum Cockpit Load without Trim Weight kg ( lb.) 1 Trim Disc is equivalent to 2,5 kp (5lb) Cockpit Load Check Weight and proper fixing to Trim Discs prior to Start. 20c A S W 2 0 - Flight Manual 1.5. Minimum Equipment Airspeed indicator with 50 to 300 km/h range ( 25 to 160 knots, 30 to 190 mph ), Lap and shoulder straps, Parachute or back-cushion at least 6 cm thick ( 2.5 inches ) when compressed, Altimeter. Additional minimum equipment for cloud flying : Turn and bank indicator, Compass, Transceiver ( Federal Republic of Germany only ) Experience to date has shown the pitot pressure system for the airspeed indicator satisfactory for cloud flying. If the compass cannot properly be compensated on the instrument panel, it should be mounted either above the control stick or on the right cockpit wall in the area above the map pocket. Instruments which weigh more than 1.000 grams ( 2.2 lbs.) should not be mounted solely with the 4 instrument screws, but should be braced against one or possibly several of the rubber buffers. It is strongly advised to use only instrument panels made from fibreglass. Panels made from other materials might, in the case of crash landings, lead to serious injuries. An equipment list of approved or suitable instruments for the minimum equipment can be found in the annex of this manual ( see page 47a and 47b). 21 A S W 2 0 - Flight Manual 1.6. Emergency Procedures Recovery from spins according to ( German ) standard procedure (1) Apply opposite rudder, i.e. against the direction of rotation of the spin. (2) Short pause. (3) Ease the control column forward, until the rotation ceases and sound airflow is established again. (4) Centralise rudder and allow sailplane to dive out. Remarks : 1. Recovery from spin can be easier achieved, if the flaps are set in negative position (handle forward). Extending the airbrakes ( spoilers ) slows down rotation speed, but needs more height for recovery and, therefore, is less recommended. 2. If the ASW 20 recovers itself from spin, it starts a spiral-like sideslip with high increase in speed. Recovery from this flight attitude is done by usual control movements ( opposite rudder and reducing bank by use of ailerons; approx. half travel of controls is needed ). Emergency Bailout (1) Open (white ) canopy locks. (2) Pull red canopy emergency release knob and push canopy upwards. (3) Open safety harnesses. (4) Try to push yourself away from the sailplane. Watch the tailplane ! Jammed Elevator Control Circuit A jammed flap control system will convert the ASW into a 'rigid profile' sailplane. However, not every pilot will remember that he still has pitch control by use of flaps even though the elevator control circuit is jammed. Thus he probably still can improve his situation for an emergency bailout or even avoid bailout entirely. 22 A S W 2 0 - Flight Manual 1.7. In Flight Information Instructions for rigging and derigging are given on pages 32 to 34. After rigging it is advisable to check all controls, dive brakes, wheel brake, and tire pressure. Even when the sailplanes is hangared it must be preflighted by checking all controls. According to experience hangared sailplanes are subject to hangar switching damages and are endangered by small animals. Winch Launch Maximum winch launch speed is 120 km/h ( 65 knots 75 mph ). Recommended flap setting is No.3 ( 0° )When the trim lever is in the centre or in slight back position, the sailplane lifts off by itself and takes to a moderate climb. When safety height is reached, slight back pressure can be applied. The landing gear can only be retracted after the tow. Winch tows with water ballast are only recommended with more than 10 knots headwind. There is a strict warning : No tailwind tows on low powered winches ! Aerotow Maximum aerotow speed is 175 km/h (94 knots, 109 mph). Tested lengths for manila or nylon tow- ropes are within the 25 - 60 m ( 80 to 200 feet ) range. For tows behind 180 hp or even stronger tow planes the tow-rope should be at least 40 m (130 feet) long. For take-off roll flap position No. 2 ( -6° ) is recommended. After about 50 km/h ( 25 knots ) have been gained, flap position No.3 ( Oo ) or even No 4 ( +9° ) is applied for earlier lift-off. 23 A S W 2 0 - Flight Manual Pilots with little experience on flapped sailplanes should use flap position No.3 for the whole tow. The pilot should try to keep the tailskid on the ground until take-off. This means several advantages. Lift-off will be at the earliest possible time. The landing gear gets lower loads. The direction stability during ground roll is considerably improved. During flight tests aerotows with stronger than 25 knots crosswinds were demonstrated. After take-off an altitude of about 5 feet should be maintained in order to avoid pitch oscillation because of ground effect and turbulence behind the towplane. Retracting of the landing gear is only allowed after release, since the landing gear doors cover the towing hook. Free Flight Because of the possibility of loading the ship with water ballast, the all up weight varies in a wide range. The following speeds are given for an all up weight of 350 kg ( 772 lbs ). The speeds for maximum all up weight of 454 kg ( 1000 lbs.) are given in brackets. Minimum speed in level zero bank flight is : For flap position 4 70 km/h or 38 knots ( 80 km/h or 43 knots ) For flap position 3 72 km/h or 39 knots ( 82 km/h or 44 knots ) For flap position 2 73 km/h or 39,5 knots ( 83 km/h or 45 knots ) For flap position 1 76 km/h or 41 knots - ( 87 km/h or 47 knots ) 24 A S W 2 0 - Flight Manual For flap position 5 ( flaps 55 down, ailerons -8 up) minimum speed in level flight is : 66 km/h or 35,5 knots ( 75 km/h or 40,5 knots ) Extending of the airbrakes ( spoilers ) increases minimum speeds by approx. 7 km/h or 4 knots. In bankings the minimum speeds age increased. An increase of 10% is valid for 30° bank, 20% are valid for 45° bank. About the proper use of flap settings this manual has already informed you at length in the preface page 8. Maximum approved wing loading is not always the most favourable, the type of flight rather has to be considered. For long distance flights ballast is not necessary, since the optimisation of weak morning and evening thermals matters and not a slightly increased cruising speed. For speed tasks the following wing loadings are proposed : 0 to 1 m/s ( 200 feet per min.), flying weight should be al low as possible ( wing loading below 33 kg/m or 6,75 lbs. per sq.ft. ) 1,5 m/s ( 300 feet per min.), flying weight about 360 kg or 800 lbs. ( wing loading 35 kg/m 2 or 7.2 lbs. per sq.ft. ) If the rate of climb is higher than 2 m/s ( 400 feet per min.), the ASW 20 should fly with max. all up weight of 454 kg ( 1000 lbs.). 25 A S W 2 0 - Flight Manual Dangerous Flight Attitudes The ASW 20 has an extremely harmless stalling flight which is indicated by large stick movements without noticeable speed change. The aileron effectivity, too, is noticeably weaker when stalling speed is reached. In all configurations approach to stall speed can be noticed by alight tail buffeting. Even in stalled flight attitude ( the vario will read 1,5 to 2 m/s sink in calm air, that is 300 to 400 feet per min. ) ailerons and rudder work in the usual manner, as long as only half control deflections are applied. Full control deflections result in light wing dropping, whereas full deflected controls in opposite directions with stick pulled completely back will cause rapid wing dropping. Initiated from turning flight wing dropping is more rapid than from level flight. The loss in altitude for wing dropping is about 20 m ( 60 feet ). For flap position 5 ( landing position ) loss in altitude can be 50 m until recovery, since the airflow may separate from the horizontal tail surface, if the elevator remains in full up deflected position. For recovery move stick in less pulled back position, until elevator effectivity is regained. Only at rear C. of G, positions ( near minimum cockpit load ) the ASW 20 will not maintain a stationary stall with the stick hard back, but starts 'porpoising'. Full deflections of rudder and aileron will cause wing dropping, opposite rudder and aileron deflections will lead to a spin. Wing dropping as well as spinning are terminated with the ( German ) standard procedure ( opposite rudder and elevator neutral, see page 22 ). If no corrective measures are taken, the sailplane will terminate the sideskid or spin by itself and will pass into a spiral-like side slip. This 26 A S W 2 0 - Flight Manual side slip can also be terminated with opposite rudder, before the ship eventually changes to a spiraldive with the typical build-up of high speeds. At forward C. of G, positions the ASW 20 spins very steeply and starts spiraldive after less than one turn, whereas at rear C. of G. positions the gliders pitch becomes steeper and steeper after an initial flat and slow turn ( approx. 30 negative pitch ) until the transition into spiral dive develops after 5 to 7 turns. Rain drops, hoarfrost, and icing deteriorate the aerodynamic flow and will cause a change in flight characteristics. Therefore, a safety margin of 10 km/h, 5 knots or 7 mph should be added to the above speeds for level flight and circling. These speeds must be regarded as minimum speeds. Again we point out that the ASW 20 spins easier and flatter with positive ( down ) flap settings ( 4 and 5 ) than with negative ( up ) flap settings ( 2 and 1 ). Therefore, setting the flaps in negative position is a measure to prevent wing dropping and spins. Because of the involved altitude losses ( about 15 m or 50 feet ) this is impossible near the ground or when thermalling in gaggles. Here only a safety margin in extra speed compared to minimum speed is good airmanship. Landing Lower tae landing gear in time, at the latest in 100 m ( 300 feet ) altitude, and put the flap lever in position No.4. The approach normally should be made at about 90 km/h or 48,5 knots ( yellow at airspeed indicator ), this speed should be trimmed. For turbulent air a correspondingly faster speed must be flown. Only if the pilot is very sure that he can make the threshold of his airstrip, the flap lever is moved to position No.5 ( flaps 55 down ). 27 A S W 2 0 - Flight Manual Because of the enormous aerodynamic twist of this flap configuration ( flap down, ailerons up ) the performance of the sailplane is bad in this flap setting. By extending of the airbrakes ( spoilers ) the performance can be further reduced ( glide ratio 4 in 1 at 85 km/h or 46 knots ) so that very steep approaches are possible with headwind. For strong headwinds flap setting No.5 is not recommended because of the danger of landing short off the field. Those pilots having no experience with flaps for landings should only use flap setting 4 for headwind landings ! Setting the flaps from position No.5 back to position No.4 is not recommended near the ground because of the danger of loss in altitude. This manoeuvre should only be done after plenty of training at a safe altitude and in a very careful manner. In flap position No.4 sideslipping is very effective with the ASW 20. At low bank and high yaw angles the loss in performance is great. In flap position No.5 such great yaw angles are impossible. Because of the good landing qualities which can be achieved by flap setting 5 in combination with the variable effectivity of the spoilers sideslipping is restricted to extreme situations (approaches in rain, snow-showers or into the sun ), since then the landing field can be observed more easily through the slide window. Therefore, landing with sideslip should be practised occasionally under good conditions. Water ballast must be dumped before landing ! 28 A S W 2 0 - Flight Manual Semi Aerobatics Besides spinning ( only with normal to rear C. of G, limits more than one turn is possible ) the following aerobatics are approved : Loops, Stall Turns, Lazy Eight, and Chandelle, as well as combinations of these manoeuvres. Negative load factors are not certified. The flap control is actuated according to the remarks in the preface ( see page 8 ). The speed limits for the different flap settings must be carefully observed. Loop A starting speed in the lowest point of about 160 to 180 km/h, 85 to 95 knots, or 100 to 112 mph is recommended. Flap setting No.1. Stall Turn A stall turn is started with 190 to 210 km/h, 102 to 113 knots, or 118 to 130 mph. At about 100 km/h 54 knots, or 62 mph the turn is started by full application of the rudder and, if need be, supported by some opposite aileron deflection. Flap setting No.1. Lazy Eight This manoeuvre can be done up to 180 km/h, 100 kts or 112 mph in the crossing point. It is an excellent practice for control and airspace co-ordination which every pilot should exercise with flap setting No.2. Chandelle This manoeuvre is started like a stall turn, however, the transition to level flight must already be initiated at 110 km/h, 60 knots, or 70 mph, by applying full rudder and full contrary aileron deflections. The stick, too, must be remarkably pushed. Flap setting No-1. Aerobatics are not approved with water ballast on board. 29 A S W 2 0 - Flight Manual A warning seems to be necessary for aerobatics : Experiences with the ASW 15 and ASW 17 as well as the flight tests show that high g-loads can be much better absorbed by the pilot in the reclined position with legs higher up than in the older gliders or even in motor aircraft. The temporary installation of a g-meter is recommended in order to get a feeling for the load factors. The rubber suspended instrument panel amplifies ground roll shocks by a factor of 1.5 whereas the low frequency g-loads in flight are read in correct manner. 1.8. Empty Weight Centre of Gravity Limits After repairs, installations of additional equipment, repainting of the sailplane etc. special attention is to be given to the empty weight centre of gravity which must remain within the permissible limits. Datum point and reference line are the same as stated in paragraph 1.3. A diagram of the empty weight centre of gravity location range is given on page 44. If these limits are maintained, it is assured that also the in-flight C. of G. is within the permissible limits provided the load limitations have been properly observed. The in-flight C. of G. has a great effect on the flight characteristics, it is, therefore, absolutely necessary to observe the prescribed limits. A C. of G. location aft of the rear limit is dangerous because this adversely affects the stall and spin characteristics. Moreover the elevator becomes hypersensitive. Excessive forward C. of G. location leads to a loss in the flight performance and prevents from flying in the maximum lift range which is very important in tight circling. 30 A S W 2 0 - Flight Manual Permanent Trimweight Installed Above Tailskid After repairs on the front fuselage, if a heavy instrumentation is installed, or if the sailplane is very often flown by heavy pilots, it is useful to install a lead trimweight in the tail. The weight of this lead ballast is determined by a weight and balance procedure. The basal surface of the cast lead should be 3,3 cm by 20 cm ( 1.3 inch by 7.9 inch ) in order to get it through the opening of the fin spar. The lead is fixed to the fuselage by 2 bolts of 8 mm diameter. For its installation the rubber tailskid has to be removed. Analogously to the resulting more tailheavy C, of G. position the minimum cockpit load is increased The new cockpit load is determined according to page 44 and to be registered on page 31. Arms for C. of G, calculations : (X P) Lightweight pilot ( 65 kg or 143 lbs.) X S = 625 mm vor BP X S = -24,6 inch forward of datum Heavy pilot ( 115 kg or 253,5 lbs.) X S = 550 mm vor BP X S = -21,65 inch forward of datum Instruments in the instrument panel X S = 1250 mm vor BP X S = -49,2 inch forward of datum Oxygen bottle ( 4 litre ) X S = 80 mm hinter BP X S = +3,15 inch behind datum 30a A S W 2 0 - Flight Manual 1.9 Centre of Gravity at the Last Weighing Signature of Examiner Maximum Payload in Cockpit inc. Parachute Minimum Empty Weight Centre of Gravity Date f Weight and Balance 31 A S W 2 0 - Flight Manual 2.1. Rigging All pins and fittings including the ball pip fittings are to be cleaned and lubricated. Insert right wing ( 2 prong-spar end )from the side into the fuselage tunnel, then left wing from the opposite aide. Align the main fittings, push in the main pins and safety. Now the wing tips can be released. Connect ailerons and dive brakes and double-check the connection by trying to pull the push-pull rods away from the ball fittings. The horizontal tail, first, is only inserted into the vertical tunnel of the fin. Then the ball fitting at the elevator is connected. And now the horizontal tail is pushed back until the Allan bolt at the nose can be screwed in. The taping of the wing-fuselage junction with a plastic Tape brings about a lot of performance with but small expenditure ( 1-2 points on the L/D). The inspection hole of the fuselage above the wings must also be taped so that its cover plate is not sucked off at high air pressure loads. Do not tape the canopy gap, otherwise any emergency exit is jeopardised. It is recommended to wax the taping area prior to taping so that the tape can be removed later on without pulling the lacquer finish off. Loading of the water ballast Water ballast must only be filled into the rigged glider. On page 20 of the Flight Manual the max. permissible amount of water in determined. 32 A S W 2 0 - Flight Manual Take care that both wings get the same amount of water. This may easily be verified by levelling the loaded glider. If the loading of water is not symmetrical, one connects both exit pipes by means of a short tube and opens both valves. With level wings the ballast will become nearly symmetric. After the balancing the valves are re-closed and the connecting tube is removed. Filling is done through the exit pipe near the landing d o o r s by using a big funnel. The filling with pressure water is strongly prohibited, because the ventilation pipe is too narrow and the water pressure becomes too strong when the reservoir is full and will blow up the wing. Each wing tank takes about 60 litres ( 15.8 USGal.). However, this maximum cannot be carried, since every lateral acceleration will press some water through the ventilation. Therefore, you either fill the tanks full up and drop one gallon ( open the valve approx.10 sec. ) or fill each side from the first with only 15 gallons. In flight the full ballast can be dropped in less than 2 minutes; this is equivalent to 1/4 USGal. per second Remark : With full tanks the wing cannot be laid down with the wing tip on the ground because then the higher wing is emptying through the ventilation pipe. 33 A S W 2 0 - Flight Manual 2.2. Checking After rigging respectively prior to the first flight every day : Make sure that all assembly connections have been properly mounted and are safetied. Check for foreign matters in the cockpit, check the controls for ease of operation. It is advisable to inspect the entire aircraft from time to time. Many a bolt without safety and many a damaged area has been noticed this way. Especially with a newly developed aircraft such inspections are very important despite of the fact that the aircraft has been designed and built with care. 2.3. Derigging First of all drop water ballast completely, disconnect the exit pipes. Derigging is done in inverted sequence like the rigging. 2.4. Road Transport The Schleicher Company can supply drawings for a light weight trailer. It is important that the wings are sitting in well fitted saddles or are supported at the spar roots as near as possible to the wing root rib. Good attachment points for the fuselage are : tail skid, wheel, wing attachment pins, and the instrument panel bulkhead. If transported on an open trailer, the ASW 20 can be made water-proof to a certain extent by taping up aileron gaps, dive brakes, canopy, pitot head and static vents. For some variometers a taping up is not allowed ( e.g. Pirol, Bohli ). 34 A S W 2 0 - Flight Manual Since we are dealing, however, with a sailplane of which the performance depends on the quality of its surface, the purchase of a light, waterproof cover or better yet of an enclosed light-coloured trailer is a good investment. It is important to keep the closed trailer well ventilated in order to avoid high temperature and high atmospheric moisture. Road transport and parking of the sailplane with water ballast is prohibited. 2.5• Upkeep and Maintenance Moisture is an enemy of fibreglass. Always take great care that no water remains in any corner. The upper dive brake boxes are not vented for performance reasons. They have to be kept dry with the aid of a sponge. On the suspicion that water has soaked into different components, one should store them in a dry room and turn them over daily. Do not underestimate the amount of condensation which can got inside an airplane. Therefore, hangars and trailers should always be well ventilated ( remove the instrument before a longer storage period ). If the glider is equipped with water tanks, special attention must be given to their maintenance. If the tanks are not needed for a longer period, they should be altogether removed. If they are in use, they should be removed and checked for leaks every month. If water is found in the wing structure, the wing must be dried in the before-mentioned manner. Afterwards the tanks ( which have to be also dry ) can be reinstalled. To do this one is using the line in the wing nose which leads to a 30 mm hole in the wing tip. 35