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发表于 2009-3-20 23:57:56
pedal pressure in a clockwise system. If cruisingairspeed is the same as, or slightly above descending airspeed, simultaneously apply the necessary cyclicpressure to obtain the approximate descending attitude.If cruising speed is well above descending airspeed, youcan maintain a level flight attitude until the airspeedapproaches the descending airspeed, then lower thenose to the descending attitude. Throughout the maneuver, maintain descending attitude and airspeed with thecyclic; descending power and r.p.m. with the collectiveand throttle; and heading with the antitorque pedals.To level off from the descent, lead the desired altitude byapproximately 10 percent of the rate of descent. For example, a 500 feet per minute rate of descent would require a50 foot lead. At this point, increase the collective to obtaincruising power, adjust the throttle to maintain r.p.m., andincrease left antitorque pedal pressure to maintain heading(right pedal pressure in a clockwise rotor system). Adjustthe cyclic to obtain cruising airspeed and a level flight attitude as the desired altitude is reached.COMMON ERRORS1. Failure to maintain constant angle of decent during training.2. Failure to lead the level-off sufficiently, whichresults in recovery below the desired altitude.3. Failure to adjust antitorque pedal pressures forchanges in power.GROUND REFERENCE MANEUVERSGround reference maneuvers are training exercisesflown to help you develop a division of attentionbetween the flight path and ground references, whilecontrolling the helicopter and watching for other aircraft in the vicinity. Prior to each maneuver, a clearingturn should be accomplished to ensure the practice areais free of conflicting traffic.RECTANGULAR COURSEThe rectangular course is a training maneuver in whichthe ground track of the helicopter is equidistant fromall sides of a selected rectangular area on the ground.While performing the maneuver, the altitude and airspeed should be held constant. The rectangular coursehelps you to develop a recognition of a drift toward oraway from a line parallel to the intended ground track.This is helpful in recognizing drift toward or from anairport runway during the various legs of the airporttraffic pattern.For this maneuver, pick a square or rectangular field,or an area bounded on four sides by section lines orroads, where the sides are approximately a mile inlength. The area selected should be well away fromother air traffic. Fly the maneuver approximately 600to 1,000 feet above the ground, which is the altitudeusually required for an airport traffic pattern. Youshould fly the helicopter parallel to and at a uniformdistance, about one-fourth to one-half mile, from thefield boundaries, not above the boundaries. For bestresults, position your flight path outside the fieldboundaries just far enough away that they may beeasily observed from either pilot seat by looking outthe side of the helicopter. If an attempt is made to flydirectly above the edges of the field, you will haveno usable reference points to start and complete theturns. In addition, the closer the track of the helicopter is to the field boundaries, the steeper the banknecessary at the turning points. Also, you should beable to see the edges of the selected field while seatedin a normal position and looking out the side of thehelicopter during either a left-hand or right-handcourse. The distance of the ground track from theedges of the field should be the same regardless ofwhether the course is flown to the left or right. Allturns should be started when your helicopter is abeamthe corners of the field boundaries. The bank normally should not exceed 30°.Although the rectangular course may be entered fromany direction, this discussion assumes entry on a9-15downwind heading. As you approach thefield boundary on the downwind leg, you should beginplanning for your turn to the crosswind leg. Since youhave a tailwind on the downwind leg, the helicopter'sgroundspeed is increased (position 1). During the turnonto the crosswind leg, which is the equivalent of thebase leg in a traffic pattern, the wind causes the helicopter to drift away from the field. To counteract thiseffect, the roll-in should be made at a fairly fast ratewith a relatively steep bank (position 2).As the turn progresses, the tailwind componentdecreases, which decreases the groundspeed.Consequently, the bank angle and rate of turn must bereduced gradually to ensure that upon completion ofthe turn, the crosswind ground track continues to be thesame distance from the edge of the field. Upon completion of the turn, the helicopter should be level andaligned with the downwind corner of the field.However, since the crosswind is now pushing youaway from the field, you must establish the proper driftcorrection by flying slightly into the wind. Therefore,the turn to crosswind should be greater than a 90°change in heading (position 3). If the turn has beenmade properly, the field boundary again appears to beone-fourth to one-half mile away. While on the crosswind leg, the wind correction should be adjusted, asnecessary, to maintain a uniform distance from the fieldboundary (position 4).As the next field boundary is being approached (position 5), plan the turn onto the upwind leg. Since a windcorrection angle is being held into the wind and towardthe field while on the crosswind leg, this next turnrequires a turn of less than 90°. Since the crosswind
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发表于 2009-3-20 23:58:12
becomes a headwind, causing the groundspeed todecrease during this turn, the bank initially must bemedium and progressively decreased as the turn proceeds. To complete the turn, time the rollout so that thehelicopter becomes level at a point aligned with thecorner of the field just as the longitudinal axis of thehelicopter again becomes parallel to the field boundary(position 6). The distance from the field boundaryshould be the same as on the other sides of the field.On the upwind leg, the wind is a headwind, whichresults in an decreased groundspeed (position 7).Consequently, enter the turn onto the next leg with afairly slow rate of roll-in, and a relatively shallow bank(position 8). As the turn progresses, gradually increasethe bank angle because the headwind component isdiminishing, resulting in an increasing groundspeed.During and after the turn onto this leg, the wind tendsto drift the helicopter toward the field boundary. ToWINDNo CrabStart TurnAt BoundaryComplete TurnAt BoundaryTurn less Than90°—Roll OutWith Crab EstablishedCrab IntoWindStart TurnAt BoundaryTurn MoreThan 90°EnterPatternComplete TurnAt BoundaryNo CrabStart TurnAt BoundaryTurn More Than90°—Roll OutWith Crab EstablishedComplete TurnAt BoundaryCrab IntoWindStart TurnAt BoundaryTurn LessThan 90°Complete TurnAt BoundaryTrackWithNoWindCorrectionTrackWithNoWindCorrectionFigure 9-15. Rectangular course. The numbered positions in the text refer to the numbers in this illustration.9-16compensate for the drift, the amount of turn must beless than 90° (position 9).Again, the rollout from this turn must be such that asthe helicopter becomes level, the nose of the helicopteris turned slightly away the field and into the wind tocorrect for drift. The helicopter should again be thesame distance from the field boundary and at the samealtitude, as on other legs. Continue the crosswind leguntil the downwind leg boundary is approached (position 10). Once more you should anticipate drift andturning radius. Since drift correction was held on thecrosswind leg, it is necessary to turn greater than 90° toalign the helicopter parallel to the downwind legboundary. Start this turn with a medium bank angle,gradually increasing it to a steeper bank as the turn progresses. Time the rollout to assure paralleling theboundary of the field as the helicopter becomes level(position 11).If you have a direct headwind or tailwind on theupwind and downwind leg, drift should not be encountered. However, it may be difficult to find a situationwhere the wind is blowing exactly parallel to the fieldboundaries. This makes it necessary to use a slightwind correction angle on all the legs. It is important toanticipate the turns to compensate for groundspeed,drift, and turning radius. When the wind is behind thehelicopter, the turn is faster and steeper; when it isahead of the helicopter, the turn is slower andshallower. These same techniques apply while flying inan airport traffic pattern.S-TURNSAnother training maneuver you might use is the S-turn,which helps you correct for wind drift in turns. Thismaneuver requires turns to the left and right. The reference line used, whether a road, railroad, or fence, shouldbe straight for a considerable distance and shouldextend as nearly perpendicular to the wind as possible.The object of S-turns is to fly a pattern of two half circles of equal size on opposite sides of the reference line. The maneuver should be performed at aconstant altitude between 600 and 1,000 feet above theterrain. S-turns may be started at any point; however,during early training it may be beneficial to start on adownwind heading. Entering downwind permits theimmediate selection of the steepest bank that is desiredthroughout the maneuver. The discussion that follows isbased on choosing a reference line that is perpendicularto the wind and starting the maneuver on a downwindheading.As the helicopter crosses the reference line, immediately establish a bank. This initial bank is the steepestused throughout the maneuver since the helicopter isheaded directly downwind and the groundspeed is at itshighest. Gradually reduce the bank, as necessary, todescribe a ground track of a half circle. Time the turnso that as the rollout is completed, the helicopter iscrossing the reference line perpendicular to it and heading directly upwind. Immediately enter a bank in the
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opposite direction to begin the second half of the “S.”Since the helicopter is now on an upwind heading, thisbank (and the one just completed before crossing thereference line) is the shallowest in the maneuver.Gradually increase the bank, as necessary, to describe aground track that is a half circle identical in size to theone previously completed on the other side of the reference line. The steepest bank in this turn should beattained just prior to rollout when the helicopter isapproaching the reference line nearest the downwindheading. Time the turn so that as the rollout is complete, the helicopter is perpendicular to the referenceline and is again heading directly downwind.In summary, the angle of bank required at any givenpoint in the maneuver is dependent on the groundspeed. The faster the groundspeed, the steeper thebank; the slower the groundspeed, the shallowerthe bank. To express it another way, the more nearlythe helicopter is to a downwind heading, the steeper thebank; the more nearly it is to an upwind heading,the shallower the bank. In addition to varying the angleof bank to correct for drift in order to maintain theproper radius of turn, the helicopter must also be flownwith a drift correction angle (crab) in relation to itsground track; except of course, when it is on directupwind or downwind headings or there is no wind. Onewould normally think of the fore and aft axis of the helicopter as being tangent to the ground track pattern ateach point. However, this is not the case. During the turnon the upwind side of the reference line (side fromwhich the wind is blowing), crab the nose of the helicopter toward the outside of the circle. During the turnon the downwind side of the reference line (side of thereference line opposite to the direction from which thewind is blowing), crab the nose of the helicopter towardthe inside of the circle. In either case, it is obvious thatPoints ofShallowest BankPoints ofSteepest BankWINDFigure 9-16. S-turns across a road.9-17the helicopter is being crabbed into the wind just as it iswhen trying to maintain a straight ground track. Theamount of crab depends upon the wind velocity andhow nearly the helicopter is to a crosswind position.The stronger the wind, the greater the crab angle at anygiven position for a turn of a given radius. The morenearly the helicopter is to a crosswind position, thegreater the crab angle. The maximum crab angle shouldbe at the point of each half circle farthest from thereference line.A standard radius for S-turns cannot be specified, sincethe radius depends on the airspeed of the helicopter,the velocity of the wind, and the initial bank chosenfor entry.TURNS AROUND A POINTThis training maneuver requires you to fly constantradius turns around a preselected point on the groundusing a bank of approximately 30°, while maintaininga constant altitude. Your objective, as inother ground reference maneuvers, is to develop theability to subconsciously control the helicopter whiledividing attention between the flight path and groundreferences, while still watching for other air traffic inthe vicinity.The factors and principles of drift correction that areinvolved in S-turns are also applicable in this maneuver. As in other ground track maneuvers, a constantradius around a point will, if any wind exists, requirea constantly changing angle of bank and angles ofwind correction. The closer the helicopter is to adirect downwind heading where the groundspeed isgreatest, the steeper the bank, and the faster the rateof turn required to establish the proper wind correction angle. The more nearly it is to a direct upwindheading where the groundspeed is least, the shallowerthe bank, and the slower the rate of turn required toestablish the proper wind correction angle. It follows,then, that throughout the maneuver, the bank and rateof turn must be gradually varied in proportion to thegroundspeed.The point selected for turns around a point should beprominent and easily distinguishable, yet small enoughto present a precise reference. Isolated trees, crossroads,or other similar small landmarks are usually suitable.The point should be in an area away from communities,livestock, or groups of people on the ground to preventpossible annoyance or hazard to others. Since themaneuver is performed between 600 and 1,000 feetAGL, the area selected should also afford an opportunity for a safe emergency autorotation in the event itbecomes necessary.To enter turns around a point, fly the helicopter on adownwind heading to one side of the selected pointat a distance equal to the desired radius of turn. Whenany significant wind exists, it is necessary to roll intothe initial bank at a rapid rate so that the steepestbank is attained abeam the point when the helicopteris headed directly downwind. By entering the maneuver while heading directly downwind, the steepestbank can be attained immediately. Thus, if a bank of30° is desired, the initial bank is 30° if the helicopteris at the correct distance from the point. Thereafter,the bank is gradually shallowed until the point isreached where the helicopter is headed directlyupwind. At this point, the bank is gradually steepeneduntil the steepest bank is again attained when heading downwind at the initial point of entry.Just as S-turns require that the helicopter be turned
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into the wind in addition to varying the bank, so doturns around a point. During the downwind half of thecircle, the helicopter’s nose must be progressivelyturned toward the inside of the circle; during theupwind half, the nose must be progressively turnedtoward the outside. The downwind half of the turnaround the point may be compared to the downwindside of the S-turn, while the upwind half of the turnaround a point may be compared to the upwind sideof the S-turn.As you become experienced in performing turnsaround a point and have a good understanding of theeffects of wind drift and varying of the bank angleand wind correction angle as required, entry into themaneuver may be from any point. When enteringthis maneuver at any point, the radius of the turnUPPERHALFOFCIRCLEDOWNWINDHALFOFCIRCLEShallowestBankSteeperBankSteepestBankShallowerBankWINDFigure 9-17. Turns around a point.9-18must be carefully selected, taking into account thewind velocity and groundspeed so that an excessivebank is not required later on to maintain the properground track.COMMON ERRORS DURING GROUNDREFERENCE MANEUVERS1. Faulty entry technique.2. Poor planning, orientation, or division ofattention.3. Uncoordinated flight control application.4. Improper correction for wind drift.5. An unsymmetrical ground track during S-TurnsAcross a Road.6. Failure to maintain selected altitude or airspeed.7. Selection of a ground reference where there is nosuitable emergency landing area within glidingdistance.TRAFFIC PATTERNSA traffic pattern is useful to control the flow of traffic, particularly at airports without operating control towers. Itaffords a measure of safety, separation, protection, andadministrative control over arriving, departing, andcircling aircraft. Due to specialized operating characteristics, airplanes and helicopters do not mix well in thesame traffic environment. At multiple-use airports,you routinely must avoid the flow of fixed-wing traffic. To do this, you need to be familiar with thepatterns typically flown by airplanes. In addition, youshould learn how to fly these patterns in case air traffic control (ATC) requests that you fly a fixed-wingtraffic pattern.A normal traffic pattern is rectangular, has five namedlegs, and a designated altitude, usually 600 to 1,000feet AGL. A pattern in which all turns are to the left iscalled a standard pattern. The takeoff leg(item 1) normally consists of the aircraft’s flight pathafter takeoff. This leg is also called the upwind leg. Youshould turn to the crosswind leg (item 2), after passingthe departure end of the runway when you are at a safealtitude. Fly the downwind leg (item 3) parallel to therunway at the designated traffic pattern altitude anddistance from the runway. Begin the base leg (item 4)at a point selected according to other traffic and windconditions. If the wind is very strong, begin the turnsooner than normal. If the wind is light, delay the turnto base. The final approach (item 5) is the path the aircraft flies immediately prior to touchdown.You may find variations at different localities and atairports with operating control towers. For example, aright-hand pattern may be designated to expedite theflow of traffic when obstacles or highly populated areasmake the use of a left-hand pattern undesirable.When approaching an airport with an operating controltower in a helicopter, it is possible to expedite traffic bystating your intentions, for example:1. (Call sign of helicopter) Robinson 8340J.2. (Position) 10 miles west.3. (Request) for landing and hover to...In order to avoid the flow of fixed-wing traffic, thetower will often clear you direct to an approach pointor to a particular runway intersection nearest yourdestination point. At uncontrolled airports, if at allpossible, you should adhere to standard practicesand patterns.Traffic pattern entry procedures at airports with anoperating control tower are specified by the controller.At uncontrolled airports, traffic pattern altitudes andentry procedures may vary according to establishedlocal procedures. The general procedure is for you toenter the pattern at a 45° angle to the downwind legabeam the midpoint of the runway. For informationconcerning traffic pattern and landing direction, youshould utilize airport advisory service or UNICOM,when available.The standard departure procedure when using thefixed-wing traffic pattern is usually straight-out, downwind, or a right-hand departure. When a control toweris in operation, you can request the type of departureyou desire. In most cases, helicopter departures aremade into the wind unless obstacles or traffic dictateotherwise. At airports without an operating control
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tower, you must comply with the departure proceduresestablished for that airport.Downwind LegBase LegFinal ApproachLegTakeoff Leg(Upwind)Crosswind LegFigure 9-18. A standard traffic pattern has turns to left andfive designated legs.9-19APPROACHESAn approach is the transition from traffic pattern altitude to either a hover or to the surface. The approachshould terminate at the hover altitude with the rate ofdescent and groundspeed reaching zero at the sametime. Approaches are categorized according to the angleof descent as normal, steep, or shallow. In this chapterwe will concentrate on the normal approach. Steep andshallow approaches are discussed in the next chapter.You should use the type of approach best suited to theexisting conditions. These conditions may includeobstacles, size and surface of the landing area, densityaltitude, wind direction and speed, and weight.Regardless of the type of approach, it should alwaysbe made to a specific, predetermined landing spot.NORMAL APPROACH TO A HOVERA normal approach uses a descent profile of between8° and 12° starting at approximately 300 feet AGL.TECHNIQUEOn final approach, at the recommended approachairspeed and at approximately 300 feet AGL, align thehelicopter with the point of intended touchdown. After intercepting an approach angle of 8°to 12°, begin the approach by lowering the collectivesufficiently to get the helicopter decelerating anddescending down the approach angle. With the decreasein the collective, the nose tends to pitch down, requiringaft cyclic to maintain the recommended approach airspeed attitude. Adjust antitorque pedals, as necessary, tomaintain longitudinal trim. You can determine the properapproach angle by relating the point of intendedtouchdown to a point on the helicopter windshield. Thecollective controls the angle of approach. If the touchdown point seems to be moving up on the windshield, theangle is becoming shallower, necessitating a slightincrease in collective. If the touchdown point movesdown on the windshield, the approach angle is becomingsteeper, requiring a slight decrease in collective. Use thecyclic to control the rate of closure or how fast your aremoving toward the touchdown point. Maintain entryairspeed until the apparent groundspeed and rate ofclosure appear to be increasing. At this point, slowlybegin decelerating with slight aft cyclic, and smoothlylower the collective to maintain approach angle. Use thecyclic to maintain a rate of closure equivalent to abrisk walk.At approximately 25 to 40 feet AGL, depending on wind,the helicopter begins to lose effective translational lift. Tocompensate for loss of effective translational lift, youmust increase the collective to maintain the approachangle, while maintaining the proper r.p.m. The increaseof collective pitch tends to make the nose rise, requiringforward cyclic to maintain the proper rate of closure.As the helicopter approaches the recommended hoveraltitude, you need to increase the collective sufficientlyto maintain the hover. At the same time you need toapply aft cyclic to stop any forward movement, whilecontrolling the heading with antitorque pedals.COMMON ERRORS1. Failing to maintain proper r.p.m. during the entireapproach.2. Improper use of the collective in controlling theangle of descent.3. Failing to make antitorque pedal corrections tocompensate for collective changes during theapproach.4. Failing to simultaneously arrive at hovering altitude and attitude with zero groundspeed.5. Low r.p.m. in transition to the hover at the end ofthe approach.6. Using too much aft cyclic close to the surface,which may result in tail rotor strikes.HImaginaryCenterlineFigure 9-19. Plan the turn to final so the helicopter rolls outon an imaginary extension of the centerline for the finalapproach path. This path should neither angle to the landing area, as shown by the helicopter on the left, nor requirean S-turn, as shown by the helicopter on the right.9-20NORMAL APPROACH TO THE SURFACEA normal approach to the surface or a no-hover landing isused if loose snow or dusty surface conditions exist.These situations could cause severely restricted visibility,or the engine could possibly ingest debris when the helicopter comes to a hover. The approach is the same as thenormal approach to a hover; however, instead of terminating at a hover, continue the approach to touchdown.Touchdown should occur with the skids level, zerogroundspeed, and a rate of descent approaching zero.TECHNIQUE:As the helicopter nears the surface, increase the collective, as necessary, to cushion the landing on the surface, terminate in a skids-level attitude with no forwardmovement.COMMON ERRORS1. Terminating at a hover, then making a verticallanding.
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2. Touching down with forward movement.3. Approaching too slow, requiring the use of excessive power during the termination.4. Approaching too fast, causing a hard landing.CROSSWIND DURING APPROACHESDuring a crosswind approach, you should crab into thewind. At approximately 50 feet of altitude, use a slip toalign the fuselage with the ground track. The rotor istilted into the wind with cyclic pressure so that thesideward movement of the helicopter and wind driftcounteract each other. Maintain the heading and groundtrack with the antitorque pedals. This technique shouldbe used on any type of crosswind approach, whether it isa shallow, normal, or steep approach.GO-AROUNDA go-around is a procedure for remaining airborne afteran intended landing is discontinued. A go-around maybe necessary when:• Instructed by the control tower.• Traffic conflict occurs.A good rule of thumb to use during an approach is tomake a go-around if the helicopter is in a position fromwhich it is not safe to continue the approach. Anytimeyou feel an approach is uncomfortable, incorrect, orpotentially dangerous, abandon the approach. The decision to make a go-around should be positive and initiatedbefore a critical situation develops. When the decision ismade, carry it out without hesitation. In most cases, whenyou initiate the go-around, power is at a low setting.Therefore, your first response is to increase collective totakeoff power. This movement is coordinated with thethrottle to maintain r.p.m., and the proper antitorque pedalto control heading. Then, establish a climb attitude andmaintain climb speed to go around for another approach.AFTER LANDING AND SECURINGWhen the flight is terminated, park the helicopterwhere it will not interfere with other aircraft and notbe a hazard to people during shutdown. Rotor downwash can cause damage to other aircraft in closeproximity, and spectators may not realize the dangeror see the rotors turning. Passengers should remain inthe helicopter with their seats belts secured until therotors have stopped turning. During the shutdownand postflight inspection, follow the manufacturer’schecklist. Any discrepancies found should be notedand, if necessary, reported to maintenance personnel.NOISE ABATEMENT PROCEDURESThe FAA, in conjunction with airport operators andcommunity leaders, is now using noise abatementprocedures to reduce the level of noise generated byaircraft departing over neighborhoods that are nearairports. The airport authority may simply request thatyou use a designated runway, wind permitting. Youalso may be asked to restrict some of your operations,such as practicing landings, during certain time periods. There are three ways to determine the noise abatement procedure at an airport. First, if there is a controltower on the field, they will assign the preferred noiseabatement runway or takeoff direction to you. Second,you can check the Airport/Facility Directory for information on local procedures. Third, there may be information for you to read in the pilot’s lounge, or evensigns posted next to a runway that will advise you onlocal procedures.10-1The maneuvers presented in this chapter require morefinesse and understanding of the helicopter and thesurrounding environment. When performing thesemaneuvers, you will probably be taking your helicopterto the edge of the safe operating envelope. Therefore, ifyou are ever in doubt about the outcome of the maneuver,you should abort the mission entirely or wait for morefavorable conditions.RECONNAISSANCE PROCEDURESAnytime you are planning to land or takeoff at an unfamiliar site, you should gather as much information asyou can about the area. Reconnaissance techniques areways of gathering this information.HIGH RECONNAISSANCEThe purpose of a high reconnaissance is to determinethe wind direction and speed, a point for touchdown,the suitability of the landing area, the approach anddeparture axes, obstacles and their effect on wind patterns, and the most suitable flight paths into and out ofthe area. When conducting a high reconnaissance, giveparticular consideration to forced landing areas in caseof an emergency.Altitude, airspeed, and flight pattern for a high reconnaissance are governed by wind and terrain features.You must strike a balance between a reconnaissanceconducted too high and one too low. It should not beflown so low that you have to divide your attentionbetween studying the area and avoiding obstructions toflight. A high reconnaissance should be flown at an altitude of 300 to 500 feet above the surface. A general ruleto follow is to ensure that sufficient altitude is availableat all times to land into the wind in case of engine failure. In addition, a 45° angle of observation generallyallows the best estimate of the height of barriers, thepresence of obstacles, the size of the area, and the slopeof the terrain. Always maintain safe altitudes and airspeeds, and keep a forced landing area within reachwhenever possible.LOW RECONNAISSANCEA low reconnaissance is accomplished during theapproach to the landing area. When flying theapproach, verify what was observed in the high reconnaissance, and check for anything new that may havebeen missed at a higher altitude, such as wires, slopes,
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and small crevices. If everything is alright, you cancomplete the approach to a landing. However, you mustmake the decision to land or go-around before effectivetranslational lift is lost.If a decision is made to complete the approach, terminate it in a hover, so you can carefully check thelanding point before lowering the helicopter to thesurface. Under certain conditions, it may be desirableto continue the approach to the surface. Once the helicopter is on the ground, maintain operating r.p.m. untilyou have checked the stability of the helicopter to besure it is in a secure and safe position.GROUND RECONNAISSANCEPrior to departing an unfamiliar location, make adetailed analysis of the area. There are several factorsto consider during this evaluation. Besides determiningthe best departure path, you must select a route that willget your helicopter from its present position to the takeoff point.Some things to consider while formulating a takeoffplan are the aircraft load, height of obstacles, the shapeof the area, and direction of the wind. If the helicopter isheavily loaded, you must determine if there is sufficientpower to clear the obstacles. Sometimes it is better topick a path over shorter obstacles than to take offdirectly into the wind. You should also evaluate theshape of the area so that you can pick a path that willgive you the most room to maneuver and abort the takeoff if necessary. Wind analysis also helps determine theroute of takeoff. The prevailing wind can be altered byobstructions on the departure path, and can significantlyaffect aircraft performance. One way to determine thewind direction is to drop some dust or grass, andobserve which way it is blowing. Keep in mind that ifthe main rotor is turning, you will need to be a sufficientdistance from the helicopter to ensure that the downwash of the blades does not give you a false indication.If possible, you should walk the route from the helicopter to the takeoff position. Evaluate obstacles that couldbe hazardous and ensure that you will have adequaterotor clearance. Once at the downwind end of the available area, mark a position for takeoff so that the tail andmain rotors have sufficient clearance from any obstructions behind the helicopter. Use a sturdy marker, suchas a heavy stone or log, so it does not blow away.10-2MAXIMUM PERFORMANCE TAKEOFFA maximum performance takeoff is used to climb at asteep angle to clear barriers in the flight path. It can beused when taking off from small areas surrounded byhigh obstacles. Before attempting a maximumperformance takeoff, you must know thoroughly thecapabilities and limitations of your equipment. Youmust also consider the wind velocity, temperature, altitude, gross weight, center-of-gravity location, andother factors affecting your technique and the performance of the helicopter.To safely accomplish this type of takeoff, there must beenough power to hover, in order to prevent the helicopter from sinking back to the surface after becomingairborne. This hover power check can be used to determine if there is sufficient power available to accomplishthis maneuver.The angle of climb for a maximum performance takeoff depends on existing conditions. The more criticalthe conditions, such as high density altitudes, calmwinds, and high gross weights, the shallower the angleof climb. In light or no wind conditions, it might benecessary to operate in the crosshatched or shadedareas of the height/velocity diagram during the beginning of this maneuver. Therefore, be aware of thecalculated risk when operating in these areas. Anengine failure at a low altitude and airspeed could placethe helicopter in a dangerous position, requiring a highdegree of skill in making a safe autorotative landing.TECHNIQUEBefore attempting a maximum performance takeoff,bring the helicopter to a hover, and determine theexcess power available by noting the differencebetween the power available and that required to hover.You should also perform a balance and flight controlcheck and note the position of the cyclic. Then positionthe helicopter into the wind and return the helicopter tothe surface. Normally, this maneuver is initiated fromthe surface. After checking the area for obstacles andother aircraft, select reference points along the takeoffpath to maintain ground track. You should also consideralternate routes in case you are not able to complete themaneuver. Begin the takeoff by getting the helicopter light on theskids (position 1). Pause and neutralize all aircraft movement. Slowly increase the collective and position thecyclic so as to break ground in a 40 knot attitude. This isapproximately the same attitude as when the helicopter islight on the skids. Continue to slowly increase the collective until the maximum power available is reached. Thislarge collective movement requires a substantial increasein pedal pressure to maintain heading (position 2). Use thecyclic, as necessary, to control movement toward thedesired flight path and, therefore, climb angle during themaneuver (position 3). Maintain rotor r.p.m. at its maximum, and do not allow it to decrease since you wouldprobably have to lower the collective to regain it. Maintainthese inputs until the helicopter clears the obstacle, or untilreaching 50 feet for demonstration purposes (position 4).Then, establish a normal climb attitude and reduce power(position 5). As in any maximum performance maneuver,the techniques you use affect the actual results. Smooth,coordinated inputs coupled with precise control allow thehelicopter to attain its maximum performance.
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COMMON ERRORS1. Failure to consider performance data, includingheight/velocity diagram.2. Nose too low initially, causing horizontal flightrather than more vertical flight.3. Failure to maintain maximum permissible r.p.m.4. Abrupt control movements.5. Failure to resume normal climb power and airspeed after clearing the obstacle.RUNNING/ROLLING TAKEOFFA running takeoff in a skid-type helicopter or a rollingtakeoff in a wheeled helicopter is sometimes used whenconditions of load and/or density altitude prevent a sustained hover at normal hovering altitude. However, youshould not attempt this maneuver if you do not havesufficient power to hover, at least momentarily. If thehelicopter cannot be hovered, its performance is unpredictable. If the helicopter cannot be raised off thesurface at all, sufficient power might not be availableto safely accomplish the maneuver. If you cannotmomentarily hover the helicopter, you must wait forconditions to improve or off-load some of the weight.To accomplish a safe running or rolling takeoff, the surface area must be of sufficient length and smoothness,and there cannot be any barriers in the flight path tointerfere with a shallow climb.For wheeled helicopters, a rolling takeoff is sometimesused to minimize the downwash created during a takeoff from a hover. Figure 10-1. Maximum performance takeoff.10-3TECHNIQUERefer to figure 10-2. To begin the maneuver, first alignthe helicopter to the takeoff path. Next, increase thethrottle to obtain takeoff r.p.m., and increase the collective smoothly until the helicopter becomes light on theskids or landing gear (position 1). Then, move thecyclic slightly forward of the neutral hovering position,and apply additional collective to start the forwardmovement (position 2). To simulate a reduced powercondition during practice, use one to two inches lessmanifold pressure, or three to five percent less torque,than that required to hover.Maintain a straight ground track with lateral cyclic andheading with antitorque pedals until a climb is established.As effective translational lift is gained, the helicopterbecomes airborne in a fairly level attitude with little or nopitching (position 3). Maintain an altitude to take advantage of ground effect, and allow the airspeed to increasetoward normal climb speed. Then, follow a climb profilethat takes you through the clear area of the height/velocitydiagram (position 4). During practice maneuvers, afteryou have climbed to an altitude of 50 feet, establish thenormal climb power setting and attitude.COMMON ERRORS1. Failing to align heading and ground track to keepsurface friction to a minimum.2. Attempting to become airborne before obtainingeffective translational lift.3. Using too much forward cyclic during the surfacerun.4. Lowering the nose too much after becoming airborne, resulting in the helicopter settling back tothe surface.5. Failing to remain below the recommended altitudeuntil airspeed approaches normal climb speed.RAPID DECELERATION (QUICK STOP)In normal operations, use the rapid deceleration or quickstop maneuver to slow the helicopter rapidly and bringit to a stationary hover. The maneuver requires a highdegree of coordination of all controls. It is practiced atan altitude that permits a safe clearance between the tailrotor and the surface throughout the maneuver, especially at the point where the pitch attitude is highest.The altitude at completion should be no higher than themaximum safe hovering altitude prescribed by the manufacturer. In selecting an altitude at which to begin themaneuver, you should take into account the overalllength of the helicopter and the height/velocity diagram.Even though the maneuver is called a rapid decelerationor quick stop, it is performed slowly and smoothly withthe primary emphasis on coordination.TECHNIQUEDuring training always perform this maneuver into thewind. After leveling off at analtitude between 25 and 40 feet, depending on the manufacturer’s recommendations, accelerate to the desiredentry speed, which is approximately 45 knots for mosttraining helicopters (position 2). The altitude youchoose should be high enough to avoid danger to thetail rotor during the flare, but low enough to stay out ofthe crosshatched or shaded areas of the height/velocitydiagram throughout the maneuver. In addition, thisaltitude should be low enough that you can bring thehelicopter to a hover during the recovery.Figure 10-2. Running/rolling takeoff.Figure 10-3. Rapid deceleration or quick stop.10-4At position 3, initiate the deceleration by applying aftcyclic to reduce forward speed. Simultaneously, lowerthe collective, as necessary, to counteract any climbingtendency. The timing must be exact. If you apply toolittle down collective for the amount of aft cyclicapplied, a climb results. If you apply too much downcollective, a descent results. A rapid application of aftcyclic requires an equally rapid application of downcollective. As collective pitch is lowered, apply properantitorque pedal pressure to maintain heading, andadjust the throttle to maintain r.p.m.
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发表于 2009-3-20 23:59:36
After attaining the desired speed (position 4), initiatethe recovery by lowering the nose and allowing the helicopter to descend to a normal hovering altitude in levelflight and zero groundspeed (position 5). During therecovery, increase collective pitch, as necessary, to stopthe helicopter at normal hovering altitude, adjust thethrottle to maintain r.p.m., and apply proper pedal pressure, as necessary, to maintain heading.COMMON ERRORS1. Initiating the maneuver by applying downcollective.2. Initially applying aft cyclic stick too rapidly,causing the helicopter to balloon.3. Failing to effectively control the rate of deceleration to accomplish the desired results.4. Allowing the helicopter to stop forward motionin a tail-low attitude.5. Failing to maintain proper r.p.m.6. Waiting too long to apply collective pitch (power)during the recovery, resulting in excessive manifold pressure or an over-torque situation whencollective pitch is applied rapidly.7. Failing to maintain a safe clearance over theterrain.8. Improper use of antitorque pedals resulting inerratic heading changes.STEEP APPROACH TO A HOVERA steep approach is used primarily when there areobstacles in the approach path that are too high to allowa normal approach. A steep approach permits entry intomost confined areas and is sometimes used to avoidareas of turbulence around a pinnacle. An approachangle of approximately 15° is considered a steepapproach. TECHNIQUEOn final approach, head your helicopter into the windand align it with the intended touchdown point at therecommended approach airspeed (position 1). Whenyou intercept an approach angle of 15°, begin theapproach by lowering the collective sufficiently tostart the helicopter descending down the approachpath and decelerating (position 2). Use the properantitorque pedal for trim. Since this angle is steeperthan a normal approach angle, you need to reduce thecollective more than that required for a normalapproach. Continue to decelerate with slight aftcyclic, and smoothly lower the collective to maintainthe approach angle. As in a normal approach,reference the touchdown point on the windshield todetermine changes in approach angle. This point is ina lower position than a normal approach. Aft cyclic isrequired to decelerate sooner than a normal approach,and the rate of closure becomes apparent at a higheraltitude. Maintain the approach angle and rate ofdescent with the collective, rate of closure with thecyclic, and trim with antitorque pedals. Use a crababove 50 feet and a slip below 50 feet for any crosswind that might be present.Loss of effective translational lift occurs higher in asteep approach (position 3), requiring an increase in thecollective to prevent settling, and more forward cyclicto achieve the proper rate of closure. Terminate theapproach at hovering altitude above the intended landing point with zero groundspeed (position 4). If powerhas been properly applied during the final portion ofthe approach, very little additional power is required inthe hover.15° DescentFigure 10-4. Steep approach to a hover.Balloon—Gaining an excessive amount of altitude as a result of anabrupt flare.10-5COMMON ERRORS1. Failing to maintain proper r.p.m. during the entireapproach.2. Improper use of collective in maintaining theselected angle of descent.3. Failing to make antitorque pedal corrections tocompensate for collective pitch changes duringthe approach.4. Slowing airspeed excessively in order to remainon the proper angle of descent.5. Inability to determine when effective translational lift is lost.6. Failing to arrive at hovering altitude and attitude,and zero groundspeed almost simultaneously.7. Low r.p.m. in transition to the hover at the end ofthe approach.8. Using too much aft cyclic close to the surface,which may result in the tail rotor striking the surface.SHALLOW APPROACH ANDRUNNING/ROLL-ON LANDINGUse a shallow approach and running landing when ahigh-density altitude or a high gross weight condition,or some combination thereof, is such that a normal orsteep approach cannot be made because of insufficientpower to hover. To compensate for thislack of power, a shallow approach and running landingmakes use of translational lift until surface contact ismade. If flying a wheeled helicopter, you can also use aroll-on landing to minimize the effect of downwash.The glide angle for a shallow approach is approximately 5°. Since the helicopter will be sliding or rollingto a stop during this maneuver, the landing area mustbe smooth and long enough to accomplish this task.TECHNIQUEA shallow approach is initiated in the same manner asthe normal approach except that a shallower angle ofdescent is maintained. The power reduction to initiatethe desired angle of descent is less than that for a normalapproach since the angle of descent is less (position 1).
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发表于 2009-3-20 23:59:52
As you lower the collective, maintain heading withproper antitorque pedal pressure, and r.p.m. with thethrottle. Maintain approach airspeed until the apparentrate of closure appears to be increasing. Then, begin toslow the helicopter with aft cyclic (position 2).As in normal and steep approaches, the primary controlfor the angle and rate of descent is the collective, whilethe cyclic primarily controls the groundspeed.However, there must be a coordination of all the controls for the maneuver to be accomplished successfully.The helicopter should arrive at the point of touchdownat or slightly above effective translational lift. Sincetranslational lift diminishes rapidly at slow airspeeds,the deceleration must be smoothly coordinated, at thesame time keeping enough lift to prevent the helicopterfrom settling abruptly.Just prior to touchdown, place the helicopter in a levelattitude with the cyclic, and maintain heading with theantitorque pedals. Use the cyclic to keep the headingand ground track identical (position 3). Allow thehelicopter to descend gently to the surface in a straightand-level attitude, cushioning the landing with thecollective. After surface contact, move the cyclicslightly forward to ensure clearance between thetailboom and the rotor disc. You should also use thecyclic to maintain the surface track. (position 4). Younormally hold the collective stationary until the helicopter stops; however, if you want more braking action,you can lower the collective slightly. Keep in mind thatdue to the increased ground friction when you lower thecollective, the helicopter’s nose might pitch forward.Exercise caution not to correct this pitching movementwith aft cyclic since this movement could result in therotor making contact with the tailboom. During thelanding, maintain normal r.p.m. with the throttle anddirectional control with the antitorque pedals.For wheeled helicopters, use the same technique exceptafter landing, lower the collective, neutralize thecontrols, and apply the brakes, as necessary, to slow thehelicopter. Do not use aft cyclic when bringing thehelicopter to a stop.COMMON ERRORS1. Assuming excessive nose-high attitude to slowthe helicopter near the surface.2. Insufficient collective and throttle to cushionlanding.3. Failing to add proper antitorque pedal as collective is added to cushion landing, resulting in atouchdown while the helicopter is moving sideward.4. Failing to maintain a speed that takes advantageof effective translational lift.5° DescentFigure 10-5. Shallow approach and running landing.10-65. Touching down at an excessive groundspeed forthe existing conditions. (Some helicopters havemaximum touchdown groundspeeds.)6. Failing to touch down in a level attitude.7. Failing to maintain proper r.p.m. during and aftertouchdown.8. Poor directional control during touchdown.SLOPE OPERATIONSPrior to conducting any slope operations, you shouldbe thoroughly familiar with the characteristics ofdynamic rollover and mast bumping, which are discussed in Chapter 11—Helicopter Emergencies. Theapproach to a slope is similar to the approach to anyother landing area. During slope operations, makeallowances for wind, barriers, and forced landing sitesin case of engine failure. Since the slope may constitutean obstruction to wind passage, you should anticipateturbulence and downdrafts.SLOPE LANDINGYou usually land a helicopter across the slope ratherthan with the slope. Landing with the helicopter facingdown the slope or downhill is not recommendedbecause of the possibility of striking the tail rotor onthe surface.TECHNIQUERefer to figure 10-6. At the termination of theapproach, move the helicopter slowly toward the slope,being careful not to turn the tail upslope. Position thehelicopter across the slope at a stabilized hover headedinto the wind over the spot of intended landing(frame 1). Downward pressure on the collective startsthe helicopter descending. As the upslope skid touchesthe ground, hesitate momentarily in a level attitude,then apply lateral cyclic in the direction of the slope(frame 2). This holds the skid against the slope whileyou continue lowering the downslope skid with the collective. As you lower the collective, continue to movethe cyclic toward the slope to maintain a fixed position(frame 3). The slope must be shallow enough so youcan hold the helicopter against it with the cyclic duringthe entire landing. A slope of 5° is considered maximum for normal operation of most helicopters.You should be aware of any abnormal vibration or mastbumping that signals maximum cyclic deflection. Ifthis occurs, abandon the landing because the slope istoo steep. In most helicopters with a counterclockwiserotor system, landings can be made on steeper slopeswhen you are holding the cyclic to the right. Whenlanding on slopes using left cyclic, some cyclic inputmust be used to overcome the translating tendency. Ifwind is not a factor, you should consider the driftingtendency when determining landing direction.After the downslope skid is on the surface, reduce thecollective to full down, and neutralize the cyclic andpedals (frame 4). Normal operating r.p.m. should bemaintained until the full weight of the helicopter is onthe landing gear. This ensures adequate r.p.m. forimmediate takeoff in case the helicopter starts slidingdown the slope. Use antitorque pedals as necessarythroughout the landing for heading control. Beforereducing the r.p.m., move the cyclic control as necessary to check that the helicopter is firmly on theground.COMMON ERRORS1. Failure to consider wind effects during theapproach and landing.2. Failure to maintain proper r.p.m. throughout theentire maneuver.3. Turning the tail of the helicopter into the slope.4. Lowering the downslope skid or wheel too rapidly.5. Applying excessive cyclic control into the slope,causing mast bumping.SLOPE TAKEOFFA slope takeoff is basically the reverse of a slope landing. Conditions that may be associatedwith the slope, such as turbulence and obstacles, mustFigure 10-6. Slope landing.10-7be considered during the takeoff. Planning shouldinclude suitable forced landing areas.TECHNIQUEBegin the takeoff by increasing r.p.m. to the normalrange with the collective full down. Then, move thecyclic toward the slope (frame 1). Holding cyclictoward the slope causes the downslope skid to rise asyou slowly raise the collective (frame 2). As the skidcomes up, move the cyclic toward the neutral position.If properly coordinated, the helicopter should attain alevel attitude as the cyclic reaches the neutral position.At the same time, use antitorque pedal pressure tomaintain heading and throttle to maintain r.p.m. Withthe helicopter level and the cyclic centered, pausemomentarily to verify everything is correct, and thengradually raise the collective to complete the liftoff(frame 3).After reaching a hover, take care to avoid hitting theground with the tail rotor. If an upslope wind exists,execute a crosswind takeoff and then make a turn intothe wind after clearing the ground with the tail rotor.COMMON ERRORS1. Failure to adjust cyclic control to keep the helicopter from sliding downslope.2. Failure to maintain proper r.p.m.3. Holding excessive cyclic into the slope as thedownslope skid is raised.4. Turning the tail of the helicopter into the slopeduring takeoff.CONFINED AREA OPERATIONSA confined area is an area where the flight of the helicopter is limited in some direction by terrain or the
