1、NASA - m N N I n z c 4 u9 4 z TECHNICAL NOTE NASA TN _. L.- D-2231 A FLIGHT INVESTIGATION OF THE PERFORMANCE, HANDLING QUALITIES, AND OPERATIONAL CHARACTERISTICS OF A DEFLECTED SLIPSTREAM STOL TRANSPORT AIRPLANE HAVING FOUR INTERCONNECTED PROPELLERS by Heruey C. Quigley, Robert C. Innis, und Curt A.
2、 Ho Zzhuuser Ames Reseurch Center M o ffett Field, Cu Zz$iorniu i NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. MARCH 1964 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-A FLIGHT INVESTIGATION OF THE PERFORMANCE, HANDLING QUALITIES
3、, AND OPERATIONAL CHARACTERISTICS OF A DEFLECTED SLIPSTREAM STOL TRANSPORT AIRPLANE HAVING FOUR INTERCONNECTED PROPELLERS By Hervey C. Quigley, Robert C. Innis, and Curt A. Holzhauser Ames Research Center Moffett Field, Calif. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Office of T
4、echnical Services, Department of Commerce, Washington, D.C. 20230 - Price $1.50 I Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-A FLIGHT INVESTIGATION OF THE PERFORMANCE, HANDLING QUALITIES, AND OPERATIONAL CHARACTERISTICS OF A DEFLECTED SLIPSTREAM
5、 STOL TRANSPORT AIRPLANE HAVING FOUR INTERCONNECTED PROPELLERS By Hervey C. Quigley, Robert C. Innis, and Curt A. Holzhauser Ames Research Center Moffett Field, Calif. SUMMARY A large four-engined aircraft having full-span triple-slotted, trailing-edge flaps and interconnected propellers was studied
6、 to gain further information on the flight and operational characteristics of typical STOL aircraft. The air- plane investigated - the Breguet 941 - had good STOL performance with the capa- bility of making a landing approach with a glide slope of about 8 at an air- speed of less than 60 knots. 50 f
7、eet obstacles, respectively, were less than 1000 feet. The STOL handling qualities of the airplane were rated satisfactory except for longitudinal static stability and the lateral-directional static and dynamic stability which were rated acceptable. considered safe to fly at the low airspeeds requir
8、ed for STOL performance. 3- The take-off and landing distances over 35 and Because of a propeller interconnect feature the airplane was INTRODUCTION The interest in STOL transport airplanes for military transport missions and for short-haul airlines has created a requirement for information on the p
9、erform- ance, handling qualities, and operational characteristics of deflected slipstream airplanes. The principle of obtaining augmented lift by deflecting the propeller slipstream with highly deflected trailing-edge flaps has been demonstrated in obtained by flying the YC-l34A, NC-l30B, and VZ-3 S
10、TOL vehicles. The results of these investigations have been reported in references 1 through 4. In France an extensive research and development program has been carried out on the deflected slipstream STOL transport airplanes by the Breguet Aircraft Company. references 5 and 6, initial studies on th
11、e Breguet 94 series date back to 1945 and the first flight on the Breguet 940 test vehicle was made in 1957. Breguet 940 demonstrated experimentally the feasibility of the highly deflected triple-slotted flap, interconnected propellers, and the use of differential out- board propeller pitch for cont
12、rol to obtain acceptable STOL performance and handling qualities. These features were then incorporated into a prototype assault transport known as the Breguet 941. Reference 5 describes some of the performance and handling qualities characteristics of the 941 aircraft in STOL operation. I flight on
13、 several airplanes. In this country, limited experience has been As noted in The Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-In order to gain additional information on the operation of large STOL aircraft, the NASA has conducted an investigation
14、of the Breguet 941 airplane, including a limited flight study in France in cooperation with the French Air Force and the Societe Anonymes des Ateliers DAviation, Louis Breguet. The results of the investigation are presented herein as representative of the char- acteristics of a current state-of-the-
15、art design. Some of the basic aircraft flight test data on which the report is based as received fromBreguet without analysis are available from Ames Research Center upon request. NOTATION longitudinal ac celerat ion, f t /s e c2/g normal acceleration, ft /s e c2/g drag coefficient including thrust
16、AZW %Js lift coefficient, - maximum lift coefficient pitching-moment coefficient longitudinal stability derivative, -, per radian longitudinal stability derivative, -, per ft/sec acceleration of gravity, ft/sec2 horizontal stabilizer angle (leading edge up, positive), deg gas generator speed, percen
17、t roll angular velocity (right roll, positive), radians/sec pitch angular velocity (nose-up, positive), radians/sec free-stream dynamic pressure, lb/ft2 %l acm that is, the left inboard and right outboard turn clockwise and the left outboard 3 Provided by IHSNot for ResaleNo reproduction or networki
18、ng permitted without license from IHS-,-,-and right inboard turn counterclockwise (see fig. 2), (3) differential outboard propeller pitch is used to augment lateral and directional control, and (4) the cockpit controls included a pilots stick for lateral and elevator control and a single throttle at
19、 the pilots left hand for all four engines. Trailing-Edge Flaps Figure 3 presents a sketch of the trailing-edge flaps. 38.5 percent of the wing chord and is constructed with three chordwise sections. The angle between the lower, or trailing edge, section and the normal wing chord - line defines the
20、flap deflection. The small middle surface is rigidly attached to the lower flap section. The upper flap section is deflected about one-half that of the lower section. The flap chord is The flap is divided into four spanwise sections on each wing. The two inboard sections are known as the internal fl
21、ap and the two outboard sections as the external flap. The aft section of the external flap serves as an aileron. The deflections for the four flap configurations tested and the notation used in this report to identify the flap configurations are as follows: I Wave-off I 75O I 5oo o/o 45/30 75/50 Fl
22、ight Cont r 01s A short control stick, about 8 inches long, on top of the control column is used to control the airplane laterally. The control stick operates ailerons, spoiler, and differential outboard propeller pitch to produce lateral control moments. Figure 4 shows the variation of the flight c
23、ontrol displacements with pilot s control displacement for all the controls. spoilers have been rigged slightly up on both wings which reduces the nonlinear effectiveness associated with spoiler deflection near zero deflection. As shown in figure 4( a), the Standard rudder pedals are used to operate
24、 the double-hinged rudder and dif- The double-hinged rudder con- At airspeeds above 100 knots, ferential propeller pitch for directional control. sists of two chordwise surfaces of about equal chords (see fig. 1). The forward surface has half the deflection of the aft surface. the forward rudder is
25、locked at zero deflection and onlythe aft surface is used and can be deflected +40. both lateral and directional control is shown in figure 4(b). The variation of differential propeller pitch with 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Lon
26、gitudinal control was provided by the control column pivoted fromthe floor. An adjustable horizontal stabilizer was normally set at +3 for take-off, at +9 for landing, and at 3-1 for cruise. The ailerons, spoilers, elevators, and rudder are actuated by an irrevers- ible hydraulic control system with
27、 control forces supplied by feel springs. The control force variation with pilot s the breakout forces and friction are outboard propeller pitch is actuated era1 control stick and rudder pedals horizontal stabilizer is actuated by trically . control displacement is shown in figure 5; also shown by t
28、hese data. The differential by a mechanical mixing system from the lat- to the propeller pitch control system. The the hydraulic system but is controlled elec- Propulsion System Power is supplied by four gas turbine engines each with a power rating of 1165 horsepower. and a free-wheeling unit. Each
29、propeller is coupled to the cross shaft through a gear box and a clutch. estimated losses due to gearing and accessories are 25 horsepower per engine. Each of the four propellers has three blades, 14.76 feet in diameter, with a max- imwn speed of 1200 rpm. Propeller characteristics used to compute t
30、he thrust coefficients are based on 0.55-scale propeller tests performed in a 26-foot wind tunnel of ONERA. These tests showed that the static propeller performance was 4.2 pounds of thrust per shaft horsepower (figure of merit equal to 0.57) at 1100 horsepower and the cruise efficiency was 82 perce
31、nt. The engines are coupled to the cross shaft through a gear train The maximum speed of the cross shaft is 6000 rpm. The The shaft and, therefore, the propeller speed is controlled by a governor which adjusts the pitch of all four propellers simultaneously. This shaft speed is set by a lever in the
32、 cockpit. The power output of each engine is determined by its gas generator speed which can be adjusted by individual engine throttles on the center pedestal in the cockpit. Further, the gas generator speed of all engines can be collectively controlled by a single power lever to the left of the pil
33、ot. This lever moves all four throttles together. Also incorporated into the single-power control lever was the control for propeller reverse pitch. It was possible to put the propeller into reverse from any throttle position. This was accomplished without unloading the engines by having the inboard
34、 propeller pitch lead the outboard propeller pitch when going to reverse pitch. There were sev- eral safety features on this control to prevent the pilot from inadvertently placing the control in reverse pitch during flight. Instrument at ion All quantities were recorded by oscillographs. Take-off a
35、nd landing dis- tances were measured by the use of a phototheodolite and direct ground measure- ment s . 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Special cockpit instrumentation included angle of attack and sideslip indi- cators. A paravisua
36、l angle-of-attack indicator (BIP) was also provided. This instrument consisted of three lights mounted above the instrument panel in the view of the pilot as he looked out of the windshield of the airplane. The lights were controlled by angle of attack. A green light indicated an angle of attack bet
37、ween 0 and +3O. Amber plus green indicated an angle of attack less than 0 while red plus green indicated an angle of attack greater than +3O. indicated an angle of attack above 13. system to provide stall warning. Red alone A stick shaker was also operated by this Test Procedures and Conditions The
38、tests were conducted at Centre D9Essais en Vol (French Flight Test Cen- ter) at Istres, France under VFR flight conditions. The flights were made by an NASA pilot in cooperation with Breguet personnel and with a Breguet test pilot and/or flight test engineer aboard. All NASA landings and take-offs w
39、ere from a concrete field at an elevation of 82 feet. A landing approach mirror was used for a portion of the landing evaluation. The airplane was flown with a take-off gross weight of 38,600 pounds with the center of gravity at 30.8 percent of MAC. The loading consisted of the test instrumentation,
40、 water ballast, and 3,200 liters (about 5,500 pounds) of fuel. Final landing gross weight was about 36,000 pounds with little change in center- of-gravity position from take-off to landing. RESULTS AND DISCUSSION The results of the investigation will be discussed in three sections enti- tled (1) Per
41、formance, (2) Handling Qualities, and (3) Operational Techniques. The lift and drag characteristics are presented in the appendix. Performance The take-off, landing, and cruise performance for the test airplane are summarized in the following table for a gross weight of 38,500 pounds. the values lis
42、ted are based on measurements made during Breguet and NASA flights. All of 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Take-off (6f = 45/30) Power Stall speed, knots Take -off speed, knots Ground roll on concrete, ft Air distance to 35 ft, ft .
43、- . Flight idle . I_ 4 - 200 sm 68 3 engine 3 - 1100 SHP 53 - - - - Lanling ( 6f = 98/65) Power (each of 4 engines) Stall speed, knots Approach speed, knots Air dish“, ft Ground roll on concrete or grass, ft -T?f-!?L Ai.St.F.c.e. over 59. ft, . $3. . . Flight idle -200 SHP 60 - .- 49 I 450 59 I 55 6
44、1 Cruise (6f = O/O) Normal continuous power each of four engines) True airspeed, knots _._._ Take-off.- The effect o gross weight on the measured ground distance over 35 feet is shown in figure 6 for take-offs on grass roll and total and concrete. Data are shown for flights made by Breguet and NASA;
45、 data obtained by Centre DEssais en Vol were used in establishing the faired average curve. are for the normal take-off configuration with an average power of 1100 horse- power per engine. The operational envelope for the airplane in the take-off configuration is presented in figure 7. iation with a
46、irspeed as well as the angle of attack required for various air- speeds. knots. The procedure used in the take-off maneuver is illustrated by figure 8 which shows a time history of a typical take-off. It can be seen that shortly after lift-off the angle of attack is reduced as airspeed increases. Al
47、though this procedure did not take complete advantage of the STOL take-off capability of the airplane, the pilots considered it an easy and safe technique. discussion of the take-off procedure is included in the Operational Techniques These data These data show the climb-out angle var- An angle of a
48、ttack of about 10 is required for a lift-off speed of 39 (Further 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-section of this report.) Calculations have shown that air distance could be reduced if higher angles of attack were maintained during
49、transition thereby utilizing the available energy to increase altitude instead of increasing airspeed so rapidly. Landing.- The variation of the computed landing distances with gross weight is shown in figure 9. Spotted on the curves are the measured ground-roll dis- tances and distances over 50 feet obtained during Breguet and NASA tests. Data
