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N A S A T E C H N I C A L N O T E N A S A TN D-4170
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' INVESTIGATION OF PITCH MANEUVER
SPEED MARGINS FOR A SUPERSONIC
TRANSPORT CONFIGURATION WITH
A VARIABLE-SWEEP WING
by Richurd H . Suwyer, Milton De McLuughlin,
und Normun S. Silsby
L.ZngZey Research Center
Langley Station, H~mpton, Va, N A T I O N A L A E R O N A U T I C S A N D S P A C E A D M I N I S T R A T I O N W A S H I N G T O N , D. C. O C T O B E R 1 9 6 7 NASA T N D-4170 INVESTIGATION O F PITCH MANEUVER S P E E D MARGINS FOR A SUPERSONIC TRANSPORT CONFIGURATION WITH A VARIABLE-SWEEP WING By R i c h a r d H. Sawyer, Milton D. McLaughlin, and Norman S. Silsby Langley Research Center Langley Station, Hampton, Va.
N A T I O N A L AERONAUTICS AND SPACE ADMINISTRATION For s a l e by t h e Clearinghouse for F e d e r a l Scientific and T e c h n i c a l Information Springfield, V i r g i n i a 22151 - CFSTI price $3.00 INVESTIGATION O F PITCH MANEUVER SPEED MARGINS F@R .A SUPERSONIC TRANSPORT CONFIGURATION WITH A VARIABLE-SWEEP WING By Richard H. Sawyer, Milton D. McLaughlin, and Norman S. Silsby Langley Research Center SUMMARY An investigation has been made of the speed and altitude excursions for 0.5g push- over and 71' upset-in-pitch maneuvers for a generalized supersonic transport (SST) con- figuration with a variable-sweep wing in order to provide information pertinent to the establishing of speed-margin requirements for the SST. A piloted fixed-base a i r c r a f t simulator was used in the investigation. Tests were made f o r level, climbing, high-speed descent, and emergency-descent flight conditions. The results show that at subsonic speeds, a 10-second 0.5g pushover maneuver would provide about the s a m e speed margin between maximum operating speed and design dive speed as a 71' 20-second upset maneu- v e r with the wings swept to either the 4 2 0 or 72O positions. Over the supersonic speed range below conditions at which the aircraft is Mach-limited, the speed margins for each of the lo-, 15-, and 20-second 0.5g pushover maneuvers were approximately constant, in lo contrast t o the speed margin for the 7- upset maneuver which increased greatly witn increase in speed. Over this speed region, the speed margin found for the 10-second 0.5g pushover maneuver generally exceeded the speed margin for the "miscellaneous causes" requirement. Over the Mach-limited flight region, the speed margin for the "miscellaneous causes" requirement exceeded the speed margins found for each of the lo-, 15-, and 20-second 0.5g pushover and the 71' 20-second upset maneuvers.
INTRODUCTION In recent revisions to the Tentative Airworthiness Standards for the supersonic l), it is proposed that the upset maneuver criterion for determining transport (SST) (ref.
the speed margin between the maximum operating speed and the design dive speed for the supersonic speed region be a 0.5g pushover maneuver rather than the 7-o 20-second upset maneuver currently specified for both subsonic and supersonic speeds. It is proposed that the 0.5g pushover maneuver be flown for the number of seconds shown to be adequate f o r subsonic operations; this proposal implies that the maneuver time chosen for the 0.5g pushover should provide a speed margin a t subsonic speeds equivalent to the speed margin provided by the 7- upset maneuver.
The proposed change from the ' 7 1 ' upset maneuver t o the 0 . 5 ~ ; pushover maneuver
lo f o r supersonic speeds is based on indications that the 7- upset maneuver may be inappro- Results of simulator tests (ref. 2 and unpublished priate for use at supersonic speeds.
North American Aviation t e s t s made for the FAA) appear to support this view.
In order to provide information pertinent to the proposed revisions to the speed- margin requirements for the SST, simulator t e s t s have been made t o determine the speed lo and altitude excursions a t both subsonic and supersonic speeds in '7% 20-second upset maneuvers and in lo-, 15-, and 20-second 0.5g pushover maneuvers. Level flight, climbing, high -speed-des cent , and emergency- des cent flight conditions were examined.
A generalized SST configuration with a variable-sweep wing was used in the study. The t e s t s were conducted with a fixed-base SST simulator. Results of these studies are pre- sented and compared with the speed-margin requirement for miscellaneous causes such as atmospheric variations, instrument e r r o r s , and a i r f r a m e production variations.
SYMBOLS D drag, pounds (newtons) acceleration due to gravity, 32.2 ft/sec2 (9.81 rn/sec2) g h altitude, feet (meters) L lift, pounds (newtons) M Mach number T thrust, pounds (newtons) design dive speed, knots VD maximum operating limit speed, knots 'MO indicated airspeed, knots Vi
w
weight, pounds (newtons)
x
wing-sweep angle, deg nominal flight-path angle, deg Y Subscript: TO take -off conditions SUPERSONIC TRANSPORT SIMULATION The supersonic transport (SST) w a s simulated by u s e of a fixed-base aircraft flight compartment linked t o a n analog computer facility. The flight compartment was r e p r e - sentative of current jet transport types with statin-ns f n r captain, first officer, ~nc! flight engineer. (See fig. 1 .) Airplane control was effected through conventional control column, rudder pedals, throttles, and trimming arrangements. The flight instruments were vertical-scale, tape-type instruments used in supersonic fighter aircraft (fig. 2).
The normal acceleration was displayed on a digital-counter readout. The flight instru- ments included a modern flight-director system.
The analog computer w a s programed with six-degree-of-freedom motion equations and the physical, aerodynamic, and control characteristics of a generalized SST config- I.) A m o r e complete description of the uration with a variable-sweep wing. (See table equipment may be found in reference 3 .
TABLE I. - SUPERSONIC TRANSPORT CHARACTERISTICS Performance:
Mach number . . . . . . . . . . . . . . . . . . . . . 0.7 1 .o 2.7
L/D . . . . . . . . . . . . . . . . . . . . . . . . . 15.0 8.1 7.7
T/W (maximum dry) . . . . . . . . . . . . . . . . 0.22 0.18 0.11
T/W (maximum afterburner thrust) . . . . . . . . . 0.30 0.26 0.22
Short-period dynamics:
Mach number . . . . . . . . . . . . . . . . . . . . . 0.7 1 .o 2.7
Longitudinal short period . . . . . .
(no damping augmentation), s e c . . . . . . . . . . 6.0 5.0 6.2
Cycles t o damp to one-half amplitude
. . . . . . . . . . . . . Critically Critically 0.1
(damping augmentation) damped damped Figure 1.- Interior view of the fixed-base supersonic transport simulator cockpit. L-67-2802 Figure 2.- View of the flight instruments used. L- 67- 2804 TENTATIVE SPEED-MARGIN REQUIREMENTS FOR THE SUPERSONIC TRANSPORT (ref. 1) for maximum operating speeds established The revised tentative standards for Federal Aviation Agency type certification of supersonic transports require that a m a r - gin be previded tc allow for inadvertent overspeecis resulting from either (1) a specified upset maneuver in pitch or (2) miscellaneous causes such as atmospheric variations, instrument e r r o r s , and a i r f r a m e production variations, whichever is the greater, with- out exceeding the design dive speed. The currently specified upset maneuver is a 71' 20-second upset in flight path. As noted in reference 1, under consideration is a proposed revision which would establish the upset maneuver for supersonic speeds to be a 0.5g push- over flown for the number of seconds shown to be adequate for current subsonic aircraft and for SST configurations while flying subsonic. This proposal thus implies that the maneuver time chosen for the 0.5g pushover should provide a speed margin at subsonic speeds equivalent to the speed margin provided by the 71' upset maneuver. The proce- d u r e s used in executing the upset and pushover maneuvers are described in the section "Test Procedure." The minimum overspeed margin specified for miscellaneous causes is 0. 05M for subsonic speeds up to M = 0.95, and 0.20M for M = 1.5 and above, with a straight-line variation of the minimum overspeed margin between M = 0.95 and 1.5.
TEST PROCEDURE for all tests, guidance being The SST simulator was operated under manual control The upset and pushover supplied entirely by the aircraft flight and navigation instruments.
maneuver tests were performed by a research engineer having piloting experience.
Time histories of altitude, Mach number, indicated airspeed, vertical speed, control surface positions, angular attitudes and velocities, normal acceleration, thrust, drag, and throttle position were recorded for each test.
The upset and pushover maneuvers were initiated at flight conditions corresponding t o points along the maximum-operating-speed-altitude VMO-h profiles between altitudes of 10 000 and 70 000 feet (3.0 and 21.3 km). At subsonic speeds, the maneuvers were ini- tiated from maximum operating speed conditions corresponding t o wing-sweep angles of 42O and 720. Supersonic speed tests were made only f o r the 720 wing-sweep condition.
The t e s t s were made for level flight, climbing, high-speed-descent, and emergency- descent flight conditions. For the level flight and climbing flight conditions, the aircraft weight was adjusted to the climb weight a t the specific altitude. Aircraft weight for the high-speed descent approximated end-of -mission letdown weight. Emergency descent weight conditions corresponded t o an emergency descent initiated immediately after establishing initial cruise. Thrust settings and spoiler, forebody, and gear positions cor- responded t o normal operating procedures. The test conditions are summarized in table 11.
TABLE E.- TEST CONDITIONS - .__.
h Vi, Spoiler Forebody Gear Flight condition knots z g w / w T o Thrust setting position position position deg
ft I km
Subsonic operations - - 42 10 x 10: 3.05 Level flight 358 1.64 0 0.974 T r i m m e d Retracted Down Level flight 4 2 20 6.07 368 .78 0 ,966 T r i m m e d Retracted Down Level flight 4 2 30 9.14 348 .90 0 ,955 T r i m m e d Retracted UP Climb 4 2 10 ,974 3.05 3 58 .64 7.6 Maximum d r y Retracted Down Climb 4 2 20 6.07 3 68 .78 4.7 ,966 Maximum d r y Retracted Down Climb 4 2 30 9.14 348 .90 2.6 ,955 Maximum d r y Retracted UP High-speed descent 4 2 10 3.05 358 .64 -8.9 .72a Idle Extended Down High-speed descent 4 2 20 6.07 368 .728 Idle .7a -6.9 Extended Down High-speed descent 4 2 30 9.14 3 4 8 .728 Idle .90 -6.5 Extended UP Level flight 7 2 15 4.57 387 .76 0 .972 T r i m m e d Retracted Down 7 2 Level flight 20 6.07 392 .84 0 .966 Trimmed Retracted Dawn 7 2 Level flight 25 7.62 410 .95 0 ,959 Trimmed Retracted UP 7 2 Climb 15 4.57 3 8 7 .76 6.3 ,972 Maximum d r y Retracted Down 7 2 Climb 20 6.07 392 .a4 4 . 6 .966 Maximum d r y Retracted Down 7 2 25 Climb 7.62 410 .95 3.2 ,959 Maxiniuiii afterburne; Retracted UP Emergency descent 72 15 4.57 387 .76 -8.4 ,853 Idle Extended Down Emergency descent 7 2 20 6.07 392 .84 -1.1 .a53 Idle Extendcd Down Emergency descent 72 25 7.62 410 .95 -6.4 .853 Idle Extended UP ~~ -~ ~~ - ...~ ~ - Supersonic oper tons - ~ __ - - 1 Level flight 9.14 458 1.15 0 0.956 Trimnied Retractcd Level flight 12.19 544 1.66 928 T r 1 in m ed Retracted Level flight 72 60 18.29 574 2.70 0 .858 T r i m m e d Retractrd Level flight 72 170 21.34 466 2.70 0 8 4 6 T r i m m e d Retracted Climb 7 2 30 9.14 458 1.15 2.0 ,956 Maximum afterburnei Retracted Climb 72 4 0 12.19 544 1.66 .I ,928 Maximum afterburne Retracted , Climb 72 60 18.29 574 ~ 2.70 .I ,858 Maximum afterburne Retracted High-speed descrnt 9.14 458 11 15 - 5 . 1 728 Idle Extendcd 1 . 1.66 High-speed descent 12.19 -3.9 ,128 Idle Extended High-speed descent 18.29 574 2.70 -.7 728 Idle Extended High-speed descent 21.34 4 6 6 2.70 -1.8 728 Idle Extended E m e r p n r y descent 9.14 458 1.15 -7.6 Extende d Emergency descent 72 4 0 12.19 -5.1 Xxtended Emergency descent 7 2 160 18.29 -2.0 Extended Emergency descent 72 65 19.81 -3.6 Extended 7- 10 20-Second Upset Maneuver The upset maneuver was initiated a t an indicated airspeed corresponding t o VMO at selected altitudes in stabilized flight, except that the flight-path angle was s e t 74' below the nominal flight-path angle. The maneuver consisted of flight for 20 seconds a t the reduced flight-path angle, and pull-up at a normal acceleration of 1.5g t o a level or climbing flight condition. The initial throttle setting was unchanged until pull-up was initiated; power w a s then reduced t o the idle setting.
0.5g Pushover Maneuver The 0.5g pushover maneuvers were initiated from stabilized flight at the s a m e altitude-maximum-operating-speed conditions as those f o r the 7 4 upset maneuvers.
The pushover maneuver consisted of a control-column-forward movement until a normal acceleration of 0.5g was reached. The 0.5g cscditisil w a s held for 10 seconds for the subsonic speed tests and f o r either 10, 15, or 20 seconds for the supersonic speed tests; a recovery at a normal acceleration of 1.5g was then made to a level or climbing flight The initial throttle setting was unchanged until pull-up was initiated; power condition.
was then reduced t o the idle setting.
RESULTS AND DISCUSSION The piloted simulator w a s used in these studies as a matter of convenience; earlier studies (ref. 2) have shown that simple point-mass calculations gave about the s a m e alti- tude and airspeed excursions as piloted-simulator tests.
Subsonic Flight Condition Speed and altitude excursions for the 71' 20-second maneuvers and 0.5g 10-second pushovers at subsonic speeds are presented in figure 3 . Results are shown for wing sweep angles X of 42O and 72O. Maximum operating speed VMO curves and the test conditions from which the maneuvers were initiated are given for each sweep angle. For X = 42O, the VMO curve reflects an aircraft operating speed limit of M = 0.9 above about 27,000 feet. The design dive speed VD curves shown were established by the maximum speed excursions in the 7 20-second upset maneuvers.
io
Inspection of the results in figure 3 indicates that with the exception of the high- speed descent flight condition, all the flight conditions tested contributed in establishing the VD envelopes. Although for this configuration the high-speed descent condition gave smaller speed excursions than the other flight conditions, it would appear that, in general, all flight conditions should be examined in determining the speed margin between VMO and VD. In the remainder of the discussion, those flight conditions which deter- VD boundary are r e f e r r e d to as the critical flight conditions.
mine the Examination of the 0.5g 10-second pushover maneuver r e s u l t s indicate that, for the critical flight conditions, the speed excursions are generally either of the s a m e magnitude or greater than the speed margin provided by the upset maneuver for both wing-sweep conditions. Thus, it appears that for the SST configuration tested a 0.5g 10-second pushover maneuver can be considered as providing a speed margin equivalent t o the 7 1 20-second upset maneuver speed margin at subsonic speeds.
.
M = 1.0 1::
I -
/
h, ft 30 1
h, km 20 1-
i6
'Mol 4 - for 7 1/2O , 20 sec upset I
0 I i I / I
250 300 350 400 450 V i , knots 7 1/Z0 0 . 59 I n i t i a l h, ft h, km 20 sec IO sec flight 20 '?- upset pus hover condition Leve I
A 2
Climb E cl High- speed I descent I Y Emergency I I I I I I / I 0 O L 250 300 350 A00 450 500 V i , knots (b) h = 720.
Figure 3.- Airspeed and altitude excursions at subsonic speeds for upset and pushover maneuvers from level, climbing, high-speed descent, and emergency- descent flight conditions on the VMO boundary.
Supersonic Flight Condition Results a t supersonic speeds of 10-second 0.5g pushover maneuvers are given in For additional information, results of 15- and 20-second 0.5g pushovers are figure 4.
given in figures 5 and 6 and results of 7 ; ' 20-second upset maneuvers in figure 7.
Design dive speed VD curves established by the maximum speed excursisns are given for each case.
Pushover maneuvers.- The results f o r the pushover maneuvers given in figures 4, 5, and 6 show that at supersonic speeds, all the flight conditions tested with the exception of the high-speed descent condition contributed in establishing the VD envelopes. This result is the s a m e as noted a t subsonic speeds; as discussed before, it appears that, in general, all flight conditions should be examined in determining the VD envelope. At speeds below the speed a t which the aircraft is Mach-limited (M = 2.7), the speed m a r - gins established by the pushover maneuvers a r e s e e n t o be approximately constant.
Over the flight region where the aircraft is Mach-limited, the speed margin is much smaller and appears t o be independent of the maneuver time.
0 I n i t i a l test condition 3 I n i t i a l flight condition 80 x 1 0 - A Level - 24
I ; Climb
I High-speed descent 0 Emergency descent - 20
M = 3. 0 I
- 1 6 / pushover / M = 1.0 , , I I i 4
lo t
I 4 o c 450 500 550 600 650 700 750 V., knots I Figure 4.- Airspeed and altitude excursions at supersonic speeds for 0.59 IO-second pushover maneuver from level, climbing, high-speed descent, and VMO boundary.
emergency-descent flight conditions on the 0 Initial test condition Initial flight condition (i Level 80 x IO a Climb 0 High-speed descent M = 3.0 1 6 h, km h, f t , , IO 1 I I I I I 400 450 5M) 550 600 650 7b0 750 V., knots Figure 5.- Airspeed and altitude excursions at supersonic speeds for 0.59 15-second pushover maneuver from level, climbing, high-speed descent, and emergency-descent flight conditions o n the VMO boundary.
0 Initial test condition Initial fliaht condition 80 lo3 h, ft IO
1"
0 L L I I I I I 1 0 400 450 Hx) 550 600 650 700 750 V., knots I Figure 6.- Airspeed and altitude excursions at supersonic speeds for 0.59 20-second pushover maneuvers from level, climbing, high-speed descent, and emergency-descent flight conditions on the VMO boundary.
.
lo Upset maneuver.- The speed margin for the 7- upset maneuver at supersonic speeds (fig. 7) is solely determined by the emergency descent condition; however, speed margins for the climb and level-flight conditions are only slightly less.
The speed m a r - gin is seen to increase greatly with speed up t o Mach-limited flight speeds. Similar t o the results for pushover maneuvers, the speed margin is small over the Mach-limited flight regime.
Comparison of pushover and upset maneuvers. - The speed-margin requirements for
0.5g pushovers and 7L0 20-second upsets are compared in figure 8. The speed-margin requirements for the upset maneuver a r e s e e n to increase from being about equivalent t o a 10-second pushover at M = 1.0 t o greater than a 20-second pushover at higher speeds.
Examination of the relative speed margins for the lo-, 15-, and 20-second pushovers indicates that the increase in speed margin with maneuver time is greater than a linear rate. Careful selection by the designer of the time for the equivalent pushover maneuver at subsonic speeds will be necessary in order to avoid establishing an excessive speed margin at supersonic speeds.
5 I n i t i a l test condition I n i t i a l f l i g h t condition c Level 80 x I O A Climb 24 0 High-speed descent 1 6 h, km h, f t 40 I?
IO I , I 1 I I I 400 450 500 550 600 6 5 4 3 700 75O V i , knots Figure 7.- Airspeed and altitude excursions at supersonic speeds for 74 20-second upset maneuvers from level, climbing, high-speed descent, and emergency-descent flight conditions o n the VMO boundary.
--- v D for 0.59 pushover
1 24
V , v for 7 112" 20 sec gpset
IO3 I I
1 4 400 450 500 550 600 650 700 750 Vi, knots Figure 8.- Comparison of speed-margin requirements for 0.59 pushover and 7 ; 20-second upset maneuvers.
Comparison of maneuvers with other speed-margin requirements. - Speed-margin
requirements for 7- 10 20-second upsets, and 0 . 5 g 10-second pushovers are compared with the "miscellaneous causes" requirements (see section "Tentative Speed-Margin Require- ments for the Supersonic Transport") in figure 9. For comparative purposes, an alterna- tive method of speed-margin determination allowed in the Federal Aviation regulations for subsonic aircraft in lieu of providing the margins required by the upset maneuver and "miscellaneous causes" provisions is also shown. The optional method, which provides that VD = 1.25VMo, has not been included in the revised tentative standards for the SST.
(See ref. 1.) The optional method calculation has been shown h e r e t o indicate the large penalties which would result from the use of such a simplified method, particularly at the higher supersonic speeds.
Comparison of the 0.5g 10-second pushover and "miscellaneous causes" speed margins show that below Mach-limited flight conditions, the "miscellaneous causes" speed margin is smaller, with the exception of the region between 37 000 and 50 000 feet (11.3 and 15.2 km). For Mach-limited flight conditions, the "miscellaneous causes" 1 0 speed margin is l a r g e r than either the 10-second pushover or 7- upset maneuver m a r gins.
_ _ _ _ _ _ 'MO -- - V for "miscellaneous causes" requirement D - -- VD for 0.59 I O sec pushover
- - v D for 7 1/2' 20 sec upset
80 lo3 V D = I. 25 VMo h, km h, ft
1 4
IO 1 0 0 450 500 550 600 650 700 750 " Vi, knots Figure 9.- Comparison of speed-margin requirements for 0.59 10-second pushover and 7 A 20-second upset maneuvers with "miscellaneous causes" requirement. Speed margin for optional calculation method (VD = 1 . 2 5 V ~ o ) also shown.
CONCLUDING REMARKS Speed-margin requirements for a generalized supersonic transport (SST) configura- tion with a variable-sweep wing have been examined with the use of a fixed-base piloted aircraft simulator. Measurements were made of the speed and altitude excursions for a 74' 20-second upset in pitch maneuver and a 0.5g pushover maneuver for lo-, 15-, and 20-second time intervals. The investigation covered level, climbing, high-speed descent, and emergency descent flight conditions at both subsonic and supersonic speeds. The subsonic speed tests were conducted at wing-sweep angles of 42O and 72'; the supersonic speed tests were conducted at a wing-sweep angle of 72O.
was found to pro- At subsonic speeds, the 0.5g pushover maneuver for 10 seconds vide about the same speed margin between the maximum operating speed and the design dive speed as the 74' 20-second upset maneuver. The 10-second pushover maneuver was
-
4s approximately equivalent t o the 7 1 upset maneuver f u r both xifig-sweep cnnditions tested.
Over the supersonic speed range, below conditions at which the aircraft is Mach- limited, the speed margins f o r each of the l o - , 15-, and 20-second 0.5g pushover maneu- v e r s were approximately constant; whereas the speed margin for the 7 1 upset maneuver increased greatly with increase in speed. Over this speed region: the speed margin found for the 10-second 0.5g pushover maneuver generally exceeded the speed margin f o r the "miscellaneous causes" requirement. Over the Mach-limited flight region, the speed margin for the "miscellaneous causes" requirement exceeded the speed margins found for each of the l o - , 15-, and 20-second 0.5g pushover and the 71' upset maneuvers.
Langley Research Center, National Aeronautics and Space Administration, Langley Station, Hampton, Va., May 18, 1967, 7 20 - 05 -00-04 -23.
REFERENCES 1. Anon. : Tentative Airworthiness Standards for Supersonic Transports. Revision 2.
Flight Standards Service, FAA, Dec. 30, 1966.
2. McLaughlin, Milton D.: Simulator Investigation of Maneuver Speed Increases of an SST Configuration i n Relation to Speed Margins. NASA T N D-4085, 1967'.
3. Sawyer, Richard H.; Stickle, Joseph W.; and Morris, Richard: A Simulator Study of the Supersonic Transport in the Air Traffic Control System. 1964 Proceedings National Aerospace Electronics Conference, IEEE, May 1964, pp. 352-356.
NASA-Langley, 1961 - 2 L-5611 15