sign in sign up
<<
Home , Airframe, Aviation Partners, Boeing Business Jet, Spar (aeronautics), Stick shaker, Wingbox

BLENDED WINGLETS FORFOR IMPROVEDIMPROVED AIRPLANEAIRPLANE PERFORMANCEPERFORMANCE

New blended winglets on the and the 737-800 commercial offer operational benefits to customers. Besides giving the a distinctive appear- ance, the winglets create more efficient flight characteristics in cruise and during takeoff and climbout, which translate into additional range with the same fuel and payload.

ROBERT FAYE ROBERT LAPRETE MICHAEL WINTER TECHNICAL DIRECTOR ASSOCIATE TECHNICAL FELLOW PRINCIPAL ENGINEER BOEING BUSINESS JETS STATIC AEROELASTIC LOADS BOEING COMMERCIAL AIRPLANES BOEING COMMERCIAL AIRPLANES BOEING COMMERCIAL AIRPLANES

TECHNOLOGY/PRODUCT DEVELOPMENT

AERO 16 vertical height of the lifting system (i.e., increasing the length of the TE that sheds the vortices). The winglets increase the spread of the vortices along the TE, creating more at the wingtips (figs. 2 and 3). The result is a reduction in induced drag (fig. 4). The maximum benefit of the induced drag reduction depends on the spanwise lift distribution on the . Theoretically, for a planar wing, induced drag is opti- mized with an elliptical lift distribution that minimizes the change in vorticity along the span. For the same amount of structural material, nonplanar wingtip devices can achieve a similar induced 737-800 TECHNICAL CHARACTERISTICS drag benefit as a planar span increase; however, new Boeing airplane designs focus on minimizing induced drag with Passengers 3-class configuration Not applicable The 737-800 commercial airplane wingspan influenced by additional design benefits. 2-class configuration 162 is one of four 737s introduced BBJ TECHNICAL CHARACTERISTICS The On derivative airplanes, performance 1-class configuration 189 in the late 1990s for short- to (BBJ) was launched in 1996 can be improved by using wingtip Cargo 1,555 ft3 (44 m3) medium-range commercial air- Not applicable as a joint venture between devices to reduce induced drag (see Passengers line operations. Demonstrating oeing offers blended Boeing and General Electric. Engines CFM56-7 “Wingtip Devices” on p. 30). Selection B Cargo Not applicable exceptional flexibility in size Designed for corporate and Maximum thrust 27,300 lb (12,394 kg) of the depends on the Engines CFM56-7 winglets — upward-swept individual use, the BBJ is a and mission, the four models — specific situation and the airplane model. Maximum thrust 27,300 lb (12,394 kg) Maximum fuel capacity 6,875 U.S. gal (26,035 L) extensions to airplane — high-performance derivative 737-600/-700/-800/-900 — An important consideration when Maximum fuel capacity Maximum takeoff weight 174,200 lb (79,015 kg) as standard equipment on its of the 737-700 commercial essentially are four sizes of the designing the wingtip device for the BBJ 10,695 U.S. gal (40,480 L) airplane. The BBJ marries the Maximum range 3,383 statute mi (5,449 km) same airplane. Two convertible BBJ 2 10,443 U.S. gal (39,525 L) BBJ was that it could be retrofitted Boeing Business Jet (BBJ) and 737-700 with the Cruise speed at 35,000 ft 0.785 Mach (530 mi/h) models are available for conver- on BBJs already in service. A blended Maximum takeoff weight stronger wing and gear of the sion to an all-freighter configu- as optional equipment on its BBJ 171,000 lb (77,565 kg) Basic dimensions winglet configuration (patented and de- 737-800 commercial airplane. BBJ 2 174,200 lb (79,015 kg) Wingspan (with winglets) 117 ft 5 in (35.79 m) ration. All the new 737s can fly signed by Dr. L. B. Gratzer of Aviation 737-800 commercial airplane. A second version of the BBJ, Overall length high-frequency, high-utilization Partners, Inc., Seattle, Washington) Maximum range 129 ft 6 in (39.48 m) called BBJ 2, was launched in Tail height Winglets also are available for BBJ 6,200 nmi (11,480 km) 41 ft 2 in (12.55 m) flights as well as transcontinental was selected because it required fewer retrofit on in-service airplanes. BBJ 2 5,750 nmi (10,650 km) 1999. Based on the 737-800 Interior cabin width 11 ft 7 in (3.53 m) and extended-range twin-engine changes to the wing structure. The commercial airplane, the BBJ 2 Cruise speed at 35,000 ft 0.785 Mach (530 mi/h) operation missions. aerodynamic advantage of a blended The 8-ft, carbon graphite has 25 percent more cabin winglet is in the transition from the Basic dimensions space and twice the cargo space existing wingtip to the vertical winglet. winglets allow an airplane Wingspan (with winglets) 117 ft 5 in (35.79 m) of the BBJ. Both provide the Overall length The blended winglet allows for the to extend its range, carry as highest levels of space, com- BBJ 110 ft 4 in (33.63 m) 1 INDUCED DRAG Induced drag distribution to change smoothly much as 6,000 lb more BBJ 2 129 ft 6 in (39.48 m) fort, and utility. BBJ customers component from the wingtip to the winglet, which payload from takeoff-limited Tail height 41 ft 2 in (12.55 m) are individuals, corporations, FIGURE optimizes the distribution of the span Interior cabin width 11 ft 7 in (3.53 m) governments, armed forces, load lift and minimizes any aerodynam- airports, and save on fuel. and heads of state. ic interference or airflow separation. Understanding the benefits of blended winglets requires Lift component knowledge of the following: the lift of the wing, the total lift vector 1 AERODYNAMICS OF WINGLETS tilts back. The aft component of this Lift 2 STRUCTURAL DESIGN 1. Aerodynamics of winglets. lift vector is the induced drag (fig. 1). force CONSIDERATIONS vector From an engineering point of view — The magnitude of the induced drag is Induced The aerodynamic benefits of a winglet 2. Structural design and ultimately that of mission capabilitydetermined by the spanwise distribution angle application are determined in part by considerations. and operating economics — the main of vortices shed downstream of the the extent of the wing modifications purpose and direct benefit of winglets wing (TE), which is made to accommodate the winglet. This 3. Design and testing. are reduced airplane drag. related in turn to the spanwise lift dis- especially is the case when an airplane tribution. Induced drag can be reduced Winglets affect the part of drag called Direction of flight model has been designed and certified 4. Retrofit and maintenance. induced drag. As air is deflected by by increasing the horizontal span or the without winglets. The magnitude of the

AERO AERO 18 19 reaches its highest loads in the clean Flutter. 2 VORTICITY CONTOURS BEHIND WING TE WITH AND WITHOUT WINGLETS wing configuration (i.e., with speed The flutter characteristics of an airplane 15.0 FIGURE brakes retracted). are evident at high speed when the condition (fig. 5). The test data from 7.5 The outboard tip of the wing generally combined structural and aerodynamic Streamwise vorticity x span this configuration were used to determine is designed for roll maneuvers. However, interaction can produce a destabilizing free-stream velocity 0 the change in air load distribution on the when winglets are added, the high loads or divergent condition. Under such cir- wing in the deflected shape. This infor- 737 BBJ winglet 737 BBJ baseline -7.5 on the winglets during sideslip maneu- cumstances, an airplane with winglets Mach = 0.78, lift coefficient = 0.50, alpha = 2.43° Mach = 0.78, lift coefficient = 0.50, alpha = 2.55° mation was used to refine the analysis -15.0 vers cause the wingtip area to be more is sensitive to the weight and center and helped minimize the adverse effects highly loaded. Therefore, sideslip ma- of gravity (CG) of the winglets and asso- 4.0 4.0 of the higher loads that resulted from ciated structural wing changes. Additional neuvers became the design case for the the winglets. weight near the wingtip, either higher wingtip and winglet. Flight tests were conducted to than or aft of the wing structural neutral 2.0 2.0 determine the cruise drag reduction of axis, will adversely affect flutter. Dynamic flight loads. the winglets and provide data on loads,

Height Height Dynamic flight loads also contribute handling qualities, and aerodynamic 0.0 0.0 to the maximum load envelope of the DESIGN AND TESTING performance. Strain gages and rows of outboard wing. The response of the 3 pressure taps placed on the winglet and to gusts or turbulence creates outboard wing were used to indicate the – 2.0 – 2.0 To design a satisfactory product that dynamic flight loads on the wing and 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 integrated performance and structural changes in bending moment on the out- winglet. During turbulence, the airframe Span Span requirements, the design team gathered board wing resulting from the winglet. responds at different frequencies de- technical data on aerodynamics, loads, Data from these flight tests were used pending on its aerodynamics, inertia, and flutter through wind tunnel and to adjust and validate the aerodynamic and stiffness. Modifications to these flight tests. database derived from the wind tunnel parameters change how the airframe 3 SPANWISE LIFT DISTRIBUTION 4 REDUCTION IN INDUCED DRAG The loads on a 737-600/-700/-800/ tests. Table 1 summarizes the aero- responds to turbulence, which in turn -900 airplane with winglets were dynamic flight test results. FIGURE FIGURE changes the loads. In addition to the analyzed through wind tunnel testing Gross fuel mileage improvement winglet-induced increase in air load, using a standard model constructed with winglets was recorded in the range 0.7 0.7 the weight of the winglet itself and its in the 1.0-g cruise shape and a unique of 4 to 5 percent. Taking into account Calculated using Maskell’s induced drag extreme outboard location also increase model. The unique wing model, the weight of the winglet and the related integrand, which is proportional to the first moment of the slope of the spanwise the loads for the outboard wing. The complete with a full set of pressure wing structural modifications, the net 0.6 0.6 change in the TE wake circulation heavier the winglets are, the higher the ports, was built in the deflected shape performance improvement was approxi- Baseline dynamic loads. for the 2.5-g design maneuver mately 4 percent for long-range flights 0.5 0.5 (fig. 6). Low-speed testing showed a significant reduction in takeoff and With winglet 0.4 0.4 737 BBJ 5 WIND TUNNEL TEST Mach = 0.78, lift coefficient = 0.50, FIGURE local wing chord / reference local wing chord / reference local wing 0.3 x x delta CDinduced = 0.00105 0.3 0.2 Baseline 0.2 737 BBJ

s induced drag 0.1 Mach = 0.78, lift coefficient = 0.50 ’ 0.1

Maskell 0.0

Sectional lift coefficient Sectional lift With winglet

0.0 – 0.1 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Span Span winglet-induced load increase and its maneuver. Although these maneuvers distribution along the wing can signifi- all contribute to the design, cantly affect the cost of modifying the Static loads. most of the wingbox is designed for wing structure. From the perspective of Static loads are determined by 2.5-g maneuvers. The highest loads on loads and dynamics, the three areas that Boeing and U.S. Federal Aviation the mid- to outboard part of the wing Image of wind tunnel model constructed affect structural change are static loads, Administration (FAA) design require-occur when speed brakes are extended. in the shape of the 2.5-g deflected wing ments, such as a symmetric 2.5-g The inboard portion of the wing superimposed over an image of the dynamic flight loads, and flutter. wing in the nominal 1.0-g cruise shape maneuver, a roll maneuver, or an abrupt input that results in a sideslip

AERO AERO 20 21 6 BLOCK FUEL IMPROVEMENTS RESULTING FROM WINGLETS 7 EFFECT OF WINGLETS ON TAKEOFF FIELD LENGTH FIGURE FIGURE 14 6 Takeoff at 5,000-ft altitude Average of eastbound and westbound block fuel improvement 12 5 Air conditioning off Zero slope Zero wind Takeoff at sea level 4 10 30°C 737-800 Category C brakes Dry runway 8 3 BBJ Weights include winglets 737-800 BBJ Cruise LRC LRC 2 OEW 91,660 lb 94,350 lb 6 Passengers 162 12 Takeoff field length, ft (000s) Takeoff Mission rules Typical mission NBAA

Percentage improvement in block fuel improvement in block Percentage 5% contingency None 737-800/CFM56-7B24 engines 1 200-nmi alternate 200-nmi alternate 4 30-min hold at 1.5 k 30-min hold at 5 k Without winglet With winglet

0 2 0 1,000 2,000 3,000 4,000 5,000 6,000 90 100 110 120 130 140 150 160 170 180 Range, nmi Takeoff gross weight, lb (000s)

PROTOTYPE WINGLET AERODYNAMIC landing drag and a significant Toe angle. PROCESS FOR WINGLET AND 1 FLIGHT TEST RESULTS benefit in payload capability The initial winglet configuration with 8 WING MODIFICATION DESIGN angle automatically at heavy weights TABLE for certain operations (fig. 7). a 0-deg toe angle was designed to mini- FIGURE and high speeds for critical design load Performance Using the information mize induced drag but resulted in high conditions. For airplanes in production, gleaned from the wind tunnel wing loads. Therefore, the winglet was a strengthened wing allows for full Four to five percent cruise drag reduction and flight tests, a winglet toed out 2 deg to reduce wing-bending speed-brake capability to be retained. No change to initial buffet boundary configuration was developed loads. The 2-deg toe angle, while Figure 10, which shows the net load that balanced the benefits reducing the loads, did not compromise reduction from changing the toe angle No change to speeds of aerodynamic performance the cruise drag. Figure 9 shows a break- and reducing the speed-brake angle, No pilot-perceived buffet before against the weight and cost down of the total drag of the winglet depicts how structural changes to the of modifying the airplane. installation as a function of toe-out wing were minimized. Flaps-down lift increase The optimal configuration angle at the cruise condition. The Structural changes. Significant drag reduction for takeoff flaps reduced loads and minimized increase in induced drag from unloading After completing the studies of the toe weight and structural modifi- the winglet was offset by the reduction angle and speed-brake angle, structural Handling qualities cations without sacrificing in trim, profile, and wave drag. A material for the mid- to outboard wing- Improved Mach tuck significant winglet perfor- performance flight test showed the drag box was still required. (Because the mance. It was achieved by was equivalent for a 0-deg toe angle Improved directional stability inboard wing had sufficient strength an iterative process during and a 2-deg toe-out angle. margins, structural changes to that Improved longitudinal and lateral trim stability which tradeoffs among critical The toe-out angle change did slightly area were minimal or unnecessary.) design functions were con- Increased pitch stability reduce the winglet-induced lift when the To minimize the adverse effects of the tinually reviewed by experts flaps were down. Induced drag is much Speed-brake angle. operators: The angle was reduced by wing structural modifications on flut- No degradation of stall characteristics and in aerodynamics, loads, flutter, greater during flaps-down operation than The mid- to outboard portion of the 50 percent for the BBJ; the 737-800 ter, wing torsional stiffness was maxi- stall identification design, and stress (fig. 8). at cruise because of the higher lift of the wing was designed for speed-brakes-up commercial airplane required full use mized in relation to bending stiffness. Unchanged rudder crossover speed Five major issues were wing. However, this loss in improved maneuver loads of 2.5 g. Loads in this of the speed brakes to the in-flight addressed in the develop- performance during flaps-down opera- area can be lowered by reducing the in- detent position for emergency descent Weight and CG control. Unchanged Dutch roll damping ment of the optimal winglet tion was considered an acceptable trade- flight speed-brake angle. The reduction certification requirements. For 737-800To address the effects of both flutter Unchanged manual reversion roll characteristics configuration. off for reduced structural modifications. in the acceptable speed-brake angle retrofits, a load alleviation system wasand dynamic load, the weight and CG depended on airplane utilization by the developed to reduce the speed-brake control of the winglet were considered

AERO AERO 22 23 TOTAL DRAG OF THE WINGLET INSTALLATION AS A 9 FUNCTION OF TOE-OUT ANGLE AT THE CRUISE CONDITION 11a AIRPLANE-LEVEL CONFIGURATION CHANGES — BBJ FIGURE FIGURE 2.5

2.0 Induced drag 1.5

1.0 APB winglet installation Wing interface with winglet 0.5 Includes navigation and New 25 and closure rib 27 (wingbox only) 0.0 anticollision lights New fittings to interface with winglet Drag counts Trim drag Replace upper and lower surface panels with – 0.5 new, thicker honeycomb panels Profile drag Modified – 1.0 Update FMC for Wave drag new aerodynamics – 1.5 Total drag – 2.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Toe-out angle (deg) In-flight speed-brake detent adjustment Reduce detent 50 percent to limit in-flight speed-brake deployment

10 WINGSPAN DESIGN CONDITIONS FIGURE 11b AIRPLANE-LEVEL CONFIGURATION CHANGES — PRODUCTION 737-800 FIGURE 2.5-g clean wing 2.5-g speed brakes up Roll, gust, sideslip Roll, gust, sideslip 2.5-g speed brakes up 2.5-g clean wing Base winglet with 20 full speed brakes

2-deg toe out Winglet installation Includes 10 navigation and anticollision lights Wing modifications New outboard 50% speed brakes panels and spar fittings Percentage change in wing-bending moment change in wing-bending Percentage

Wing root Percentage of wing semispan Wingtip Strengthened wing Design conditions typically vary throughout the wingspan. Inboard wing: symmetric 2.5-g maneuver Avionics revision Midwing: 2.5-g speed brakes deployed FMC performance update Outboard wing: roll, gust, or sideslip maneuver

AERO AERO 24 25 REMOVAL OF OUTBOARD UPPER INSTALLATION OF THE SPAR ATTACH FITTINGS AIRPLANE-LEVEL CONFIGURATION CHANGES — RETROFIT 737-800 11c 12a AND LOWER SKIN PANELS 12d AND FINAL ASSEMBLY OF WING MODIFICATION FIGURE FIGURE FIGURE

Winglet installation Wing modifications Includes New outboard panels navigation and and fittings anticollision lights Strengthened stringers Revised fasteners

Avionics revision REMOVAL AND REPLACEMENT OF RIB 25 12e INSTALLATION OF WINGLET FMC performance update 12b AND THE CENTER SECTION OF RIB 27 FIGURE FIGURE

In-flight speed-brake load limiter Does not affect normal operations

carefully, including the location of the winglet lights and specifications for Analysis indicated that no additional 4 RETROFIT AND MAINTENANCE the painting and possible repair of the rework was required for the BBJ. winglet. To meet flutter requirements Because of the higher cycles of air- The wing modification was designed with minimal structural changes, addi- plane utilization and takeoff weights with retrofit in mind. Once the wing tional wingtip ballast was mounted on has been modified for winglets, the INSTALLATION OF THE NEW CENTER SECTION OF of the 737-800 commercial airplane, 12c RIB 27 AND THE NEW WINGLET ATTACH FITTING the front spar to counteract the incre- winglet itself can be replaced within some wing panel fastener holes require FIGURE mental weight of the winglet located aft rework for considerations on three hours. The more time-consuming on the wing. The use of wingtip ballast retrofitted airplanes. The inspection part of the retrofit is installation of the depended on the structural configuration intervals for the wing modification wing modification to accommodate the of the wing. In some cases, ballast was and winglet structure are the same as winglet. For example, a BBJ retrofit, simpler and more cost effective than those for all 737-600/-700/-800/-900 accomplished according to an FAA structural modification of the wingbox. airplanes. supplemental-, involves the following tasks. (This listing does No wingtip ballast is required for the The overall scope of the wing BBJ configuration; 75 lb of ballast per not constitute a complete work instruc- modification for the BBJ involves wing is required for each production tion package.) 10 percent of the outboard wing. This winglet on the 737-800 commercial air- small percentage results from the 2-deg plane; 90 lb of ballast is required per change in winglet toe angle and the Removal and replacement of the wing for 737-800 retrofit. 50 percent reduction in the in-flight outboard upper and lower skin panels speed-brake angle. For the 737-800 (fig. 12a). Damage tolerance and fatigue. retrofit, the modification involves Removal and replacement of rib 25, The winglet and the wing modifications 35 percent of the outboard wing. The which is third from the outermost rib Installation of the new center section of rib 27 and the Retrofit of the 737-800 commercial airplane includes a were designed to meet Boeing and production airplane with full speed- (fig. 12b). new winglet attach fitting (fig. 12c). load alleviation system to obtain full use of the speed brakes FAA criteria for damage tolerance and brake capability involved wing panel to the in-flight detent position during typical opera- Installation of the spar attach fittings (fig. 12d). fatigue. Any unchanged structure affect- changes that affect 60 percent of the Installation of stiffeners across rib 25. tions. The system, which is installed in the flight deck aisle ed by the increased loads was analyzed span. Figure 11 shows airplane-level Cutting of the closure rib (rib 27) and Installation of the aft-position light. stand, arms at heavy weights and high speeds at extreme to ensure that all requirements were met. configuration changes. trimming of the two spars (fig. 12b). Installation of the winglet (fig. 12e). portions of the flight envelope. When armed, the system

AERO AERO 26 27 actuates the in-flight speed-brake handles and retracts them to 50 percent. For airplanes in production, the wings are strengthened throughout the wingbox to accommodate the winglet loads with full use of the speed brakes SUMMARY to the in-flight detent position. The in- Blended winglets offer operational production modification meets the same design criteria as those for the retrofit. and economic benefits to BBJ and However, during production, structural 737-800 customers. Mission block strengthening is accomplished by fuel is improved approximately increasing the gage of spars, stringers, ribs, and panels. Rib 27 incorporates 4 percent. Range capability is bolt hole patterns that allow attachment increased by as much as 200 nmi of either a winglet or a standard wingtip. The winglet is installed in final assembly. on the BBJ and 130 nmi on the Navigation and strobe lights are 737-800 commercial airplane. The mounted on the (LE) of reduction in takeoff drag during the winglet in a way similar to that of the basic wingtip for production. the second segment of climb allows Replacement of the winglet forward- increased payload capability at position light, strobe light, and lens requires removal of the LE assembly takeoff-limited airports. from the winglet. The winglet aft- Environmental benefits include a position lights are easily accessible 6.5 percent reduction in noise levels for maintenance. Except for replacement of the winglet around airports on takeoff and a forward-position lights and strobe lights, 4 percent reduction in nitrogen dioxide the winglets minimally affect in-service maintenance of the airplane, and the emissions on a 2,000-nmi flight. design allows for The blended winglets now are a wide range of available as standard equipment structural repairs. Primary materials 13 BLENDED WINGLET STRUCTURE on BBJs, as optional equipment on are graphite spars, FIGURE 737-800 commercial airplanes, and honeycomb gra- FWD Aluminum LE skins phite panels, and by retrofit for BBJs, 737-800, D aluminum LE Graphite spars INB and 737-700 commercial airplanes Aluminum tip and interface joints already in service. Because the (fig. 13). Designed to meet Boeing and winglet structure and systems follow Aluminum ribs FAA criteria for splice plates established maintenance intervals fatigue and damage tolerance, the wing- Position and and life cycles, winglets have a mini- let structure and Aluminum strobe lights mal effect on airplane maintenance. systems fit within TE arrowhead current airplane maintenance inter- vals and life cycles, Graphite with honeycomb with the exception upper and lower skins of the 737-800 lens, which has a Blind fasteners upper skin attach Aluminum temporary certifi- Huck bolts lower skin attach interchangeable Editor’s note: The 737 BBJ blended winglets are patented by Dr. L. B. Gratzer cation maintenance No bonding interface joint Aft position light of , Inc. (API), Seattle, Washington. Boeing and API formed requirement. a joint venture, Aviation Partners Boeing, during the development of the 737 BBJ blended winglet design. This article was provided solely by Boeing.

AERO AERO 28 29 767-400 WINGTIP DEVICES

Wingtip devices on derivative airplanes can improve performance by 747-400 reducing induced drag. Selection of the wingtip device depends on the specific situation and the airplane model. 747-400. The 747-400 commercial airplane needed a significant span increase to meet the range requirement. However, structural constraints prevented the total span increase, so a combination of winglet and span increase was used. 767-400. BBJ and 737-800 Following a business-case study of the benefits of adding winglets or increasing wingspan, the 767-400 program chose a span increase in the form of a raked tip. MD-11 BBJ and 737-800. Drag Reduction of Wingtip Device The wingtip device for the BBJ and 737-800 commercial airplane involved 6 a retrofit of existing wings. The blended winglet was selected because it required minimal changes to the wing structure and provided improved 5 aesthetic appeal for the BBJ.

MD-11. 4 The MD-11 program chose a winglet based on wingspan constraints and minimum structural weight. 3 KC-135. The U.S. Air Force and the National Aeronautics and Space Administration KC-135 winglet conducted a winglet development 2 KC-135 program in 1978 to understand how MD-11 extended winglet winglets could improve performance. 747-400 tip plus winglet Percentage of drag reduction at average cruise 1 737-800 blended winglet 767-400 raked tip

0 0 2 4 6 8 10 12 14 16 18 Percentage increase in horizontal and vertical span

AERO AERO 30 31