Resume of Handling Qualities of the X-15 Airplane

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(CODE) XL CONFIDENTIAL NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TECHNICAL MEMORANDUM X-715 0 _'-I I C.D RESUME OF HANDLING QUALITIES OF THE X-15 AIRPLANE* ** H 0 By Robert M. White, Glenn H. Robinson, and Gene J. Matranga E-g c.._ I-.I H

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The handling qualities of the X-15 research airplane are assessed _ _t ,,-,I c3%yI from pilot opinion_ with verification in many cases by data acquired during flights. Areas of interest covered are the launch, climbout, semiballistic flight, atmosphere entry_ and landing phases of X-15 flight s.

INTRODUCTION The concept of aircraft handling qualities has been specified since World War II to provide certain performance features, such as rolling velocity and stall warning_ and a desired level of static and dynamic stability to allow the pilot to fly the aircraft with relative ease. Although great efforts have been made toassign quantitative values to these parameters, to a great extent how the airplane flies is assessed through pilot opinion. Both pilots and engineering analysts might do well to accept this thesis, for to quote one well-used text book (ref. i): "The desired magnitude of dihedral effect has never been very successfully determined. From the analysis of many stability and control flight tests, it has become apparent the pilot likes to have some dihedral effect, but not too much."

This r@sum@ covers in broad aspects many of the handling features of the X-I_ from launch to landing. Some conclusions can be drawn, but many comments regarding handling-quality specifications for hypersonic and high-altitude flight must be delayed until future flights are made and the data thoroughly examined.

*This document is based on a paper presented at the Conference on the Progress of the X-15 Project, Edwards Air Force Base, Calif., November 20-21_ 1961.

**Title, Unclassified.

CONFIDENTIAL SYMBOLS longitudinal acceleration_ g units

at

normal acceleration_ g units an g acceleration due to gravity M Mach number maximum angular rolling velocity_ deg/sec

Pmax

angular pitching acceleration_ deg/sec 2 dynamic pressure, ib/sq ft maximum dynamic pressure_ ib/sq ft average wing loading_ ib/sq ft

(W/S)av

angle of attack_ deg trim angle of attack_ deg _trim angle of sideslip, deg maximum roll-angle increment_ deg _h horizontal-tail deflection_ deg damping ratio pitch angle_ deg natural frequency in pitch_ radians/sec % X-15 COCKPIT Since frequent reference will be made to the pilot's cockpit_ some of the salient items used for display and control are shown in figure i.

The display is conventionalin that it shows in standard fashion the operating level of many of the aircraft and engine systems. The flight phase is monitored chiefly from the inertial system which provides

CONFIDENTIAL 3

readout in altitude_ velocity, and aircraft attitude. Additions from the flow-direction-sensor ball nose provide pointers and cross bars that allow the pilot a reading of angle of attack and vernier indications of angle of attack and sideslip. Prime reliance is placed on the attitude indicator in three axes_ inasmuch as the earth's horizon is quickly lost as an outside reference during the high-pitch-angle climb experienced on all flights. Simplicity is the key, and small changes are being made continually_ as requested by the pilots, to provide a readable display for the rapid cross checks that a pilot makes in a fast-moving situation.

H

Control is afforded in several ways. Aerodynamic control is provided by a conventional center stick or by an interconnected side stick positioned to allow pilot control without inadvertent or adverse inputs from acceleration forces. Reaction control for attitude control at low dynamic pressure is given by a simple controller on the left side of the cockpit that allows inputs in roll, pitch, and yaw.

LAUNCH AND CLIMBOUT Two areas common to all flights, the launch and initial climbout, have been studied in detail. The launch is characterized by two prom- inent features: first_ a sudden departure from the B-52 pylon, yielding a zero g peak normal acceleration_ and_ second, an abrupt roll-off to the right that rarely exceeds a i0 ° to 15 ° change in bank angle. The release is what might be expected and_ after the first experience_ is of no concern to the pilot inasmuch as normal i g flight is regained within 2 seconds. The roll-off at launch stops as the X-15 emerges from the B-52 flow field. Since the bank-angle change is smali_ it is easily and quickly corrected. Launch has been made by using either the center or side aerodynamic control stick_ with equal satisfaction in both cases. In addition_ launch has been made with the control neutral, correcting the roll-off as it occurred, and with small lateral-control input to counteract the roll before it could develop. Both methods have been acceptable and resolve into individual pilot's technique and preference.

Immediately after launch the engine is fired and the climbout begins. Assumej for a moment, that a long delay occurs before engine ignition, which has been true on several occasions. The pilot glides at an angle of attack of 8 ° , which is near the best lift-drag ratio for glide; the aircraft responds well and is free of buffet. If angle of attack is increased to i0°_ a mild buffet onset is immediately detected, which allows the pilot to make corrections well in advance of a stall condition. The aerodynamic qualities, then, at 45,000 feet, a Mach number of 0.8, and maximum weight are considered excellent. Very

4 CONFIDENTIAL

quickly after engine light-off, supersonic speed is reached and an

angle of attack of i0 ° is maintained to rotate the airplane to a climb-

out pitch angle that is established by the mission requirement. Buffet

is absent above a Machnumber of 1.0, but a nosedowntrim change occurs

between Machnumbers of i.i _ud 1.4. Figure 2 illustrates this trim

change. Note that the piloting task in the low-supersonic speed range

calls for constant angle of attack. In order to maintain constant

angle of attack, the pilot must trim in substantial up-stabilizer.

Frequently, the speed change is so rapid (approximately 6 seconds from

M = i.i to 1.4) that the pilot has difficulty keeping up with the trim

change. As a result, the angle of attack in this speed range is

usually lower than desired. The trim change is mild, however, and has

not received theobjections from pilots that have often been given to

the more abrupt trim change in the transonic region below a Mach number

of 1.0 that occurs on many jet aircraft.

CONTROL CHARACTERISTICS

Figure 3 presents the details of an altitude mission which reached

217,000 feet and which enables many commentsto be madepertinent to

X-15 flight control characteristics. After initial rotation at an angle

of attack of i0 °, a constant pitch angle of 32° is established and

maintained to burnout where the acceleration along the longitudinal

axis a_ reached 3.6g. From engine burnout until the reentry, the

aircraft followed a ballistic trajectory. Two unique features that

occurred are weightlessness experienced by the pilot for about 2 minutes

and the requirement that reaction controls be used since dynamic

pressures have decreased to a minimumof 3 pounds per square foot at

peak altitude. This part of the flight is followed by the reentry

maneuver, which terminates when the aircraft rotates to level flight

after experiencing, as in this case, normal acceleration an of 3.8g,

longitudinal acceleration of -2.2g, and peak dynamic pressure in

excess of 1,400 pounds per square foot.

The portion of the profile during exit is particularly pleasing to

the pilot since the airplane is very stable and the damping appears

adequate, even with roll and yaw dampers failed. The increase in

acceleration along the longitudinal axis during the thrust period

reaches a maximumof 3.6g at burnout. The acceleration level, although

certainly noticeable to the pilot, has not been high enough to provide

any adverse commentin regard to impairing the pilot's ability to perform

his essential tasks. Thrust termination during flight occurs when the

pilot stops the engine or when burnout results from propellant exhaustion.

In all cases there have been no transient aircraft motions, and thrust

misalinement has not been a factor of concern. The stabilizer is trimmed

to maintain an angle of attack of 0°. This change in trim is complete at

CONFIDENTIAL 5

approximately 145,000 feet, where dynamic pressure has decreased to

26 pounds per square foot. At this point a decay in response to aero-

dynamic control is easily noted by the pilot, and reaction controls are

then employed. The reaction controls proved to be very effective,

aircraft response to inputs in roll and yaw were good, and the response

in pitch was more than desired and caused somedifficulty in damping

the pitch oscillations.

Ballistic Control

The motions in the ballistic flight region can best be illustrated

by the time history shown in figure 4, which includes that part of

flight at dynamic pressures of less than i0 pounds per square foot.

Plotted are the angle of attack and airplane pitching acceleration

which developed as a result of the use of reaction control. All

reaction-control inputs were essentially in the proper direction to

dampthe airplane motion except at one point where the angle-of-attack

oscillation experienced its largest excursion. At this point an input

was madethat reinforced the increase in angle of attack, but immediately

afterward the pilot was able to dampthe oscillation adequately to

maintain the desired angle of attack. Although the longitudinal control

task was complicated by the presence of an out-of-trim stabilizer condi-

tion, the results are indicative of control difficulties that can be

encountered with an acceleration-command reaction control system. Since

this figure presents results of the first and only significant reaction-

control experience with the X-15, proper longitudinal control trim and

pilot experience are expected to yield an improvement in airplane

attitude control at low dynamic pressure. The excursions in sideslip

were contained to acceptable limits by using reaction control. Similar

results were evident in bank-angle control. Lateral-aerodynamic-control

inputs were used at low dynamic pressure with no apparent response

comparedwith the good response and control afforded by reaction control.

Pilot technique in this region was use of reaction control in one axis

at a time.

Zero g, although an interesting area to consider_ has had no

noticeable effect on the pilot control task for the approximate 2-minute

period during which the weightless state was experienced.

The presentation for control is provided by cross bars, shown in

figure 5_ to allow flying at prescribed values of angles of attack and

sideslip. As can be seen_ these bars are incorporated within the face

of the attitude indicator which additionally provides roll information

for control inputs. Inasmuch as the pilot is nowmanually controlling

attitude about three axes without any damping system, the instrument

presentation is considered adequate; all information is displayed

centrally and minimizes scanning and instrument cross-check.

6 CONFIDENTIAL

Control During Reentry

The reentry maneuver is perhaps the most interesting from the

pilot's standpoint_ since it is flown at relatively high angles of

attack and under rapidly changing conditions of dynamic pressure, temper-

ature, and velocity, with the associated changes in aircraft stability

and responses. The maneuver actually begins as the aircraft passes

through 180,000 feet (see fig. 3) where the stabilizer is trimmed to a

value that will maintain reentry normal acceleration. The reaction

control is used to establish the reentry angle of attack.

The time history shownin figure 6 begins immediately after the

stabilizer has been trimmed for reentry. With the stabilizer constant

and the angle of attack raised to i0°_ the normal acceleration an

increases to approximately 2g as the dynamic pressure _ increases.

The angle-of-attack decrease results from a repositioning of the

stabilizer to maintain the reentry acceleration until level flight is

regained just above 60,000 feet. Returning to the point where reentry

angle of attack was reached_ but just prior to significant change in

dynamic pressure_ a sideslip oscillation developed but was low enough

in magnitude and frequency to be disregarded by the pilot, particularly

since it dampedadequately as dynamic pressure increased. It is

interesting to note that the static simulations and the Johnsville

centrifuge program provided good training for these conditions so that

the actual reentry did not result in a completely new or unexpected flight

experience.

Other Control Features

Several features, common to all flights_ can be noted prior to a

discussion of the terminal and landing phases of the X-15.

The speed brakes have been used in many areas throughout the speed

and altitude range_ under thrust, and after engine shutdown. Except

for incremental use in the landing pattern_ they have always been

extended symmetrically, that is_ with equal brake deflection for the

segmentsboth above and below the fuselage_ and opened to full deflection.

During extension there is a mild trim change. Aside from the trim change,

no undesirable aircraft motions have been experienced with speed-brake

use; the brakes are extremely effective, and there has never been a

report of buffet due to speed-brake deflection.

Lateral control of the aircraft has been effected by differential

deflection of the horizontal stabilizer_ that is_ the so-called "rolling

tail." This method of lateral control has been excellent on the X-15.

The pilot is not aware of what specific type of lateral control is

allowing the roll motion. His only concern is in being able to get the

CONFIDENTIAL 7 aircraft response he calls for when deflecting the control stick.

Figure 7 shows many representative points obtained in flight and illus- trates the comparatively low roll rates and moderate bank-angle changes associated with the X-15 mission. From the flight experience, the rolling tail has provided a good rolling control for the X-15, and there have been no undesirable aircraft motions coupled in any axis because Of lateral-control deflection. It is true that inertial coupling is a factor under specific conditions of dynamic pressure, angle of attack_ and rolling velocity, but no attempt has been made to H verify such predictions by specific roll-performance flight tests_ aside from determining lateral effectiveness and using roll control only as required on any particular flight.

The stability-augmentation system which provides rate damping about all axes has had significant effect on pilot opinion. During early flights below a Mach number of 3.5_ moderate gains were used. Pilot opinion expressed a desire for a stiffer aircraft_ particularly in pitch and roll, and flights above M = 3-5 have used considerably higher gains. In general_ pilot opinion of the augmented handling qualities in the Mach number range from 2.5 to 6.0 has been favorable. It is interesting to note that_ at an angle of attack of 8 ° and above with low damper gain and particularly with roll or roll and yaw dampers off, the pilot has great difficulty in controlling the lateral and directional motions to prevent divergence. This difficulty is caused primarily by an adverse dihedral effect which is present at Mach numbers above 2.3.

This problem has received a great deal of attention. A summary of the area of unaugmented X-15 lateral and directional characteristics is presented in reference 2. With dampers set at high gain_ however, the lateral and directional characteristics have been acceptable to the highest angle of attack explored, approximately 17 °.

The pilot ratings (P.R.) for longitudinal controllability are summarized in figure 8 as a function of frequency _n and damping ratio and are compared with criteria developed by the Ames Research Center (ref. 3) from simulator studies of reentry vehicles. The X-15 flight data obtained during powered and unpowered flight are shown by circular symbols (according to pilot rating)_ and the comparative Ames results are indicated by the curves. Most of the X-15 data have satisfactory ratings including one of the two points representing damper-off conditions. In general, the correlation between the X-15 flight points and the Ames criteria is good. It appears, however_ that the damper- off points were rated in flight more favorably than would be predicted from simulator results.

The side aerodynamic control stick designed for the X-15 has received the usual critical analysis associated with a departure from

CONFIDENTIAL

the conventional control. Most of the factors considered are included

in the following tabulation:

Force gradients - sensitivity

Dead band - centering

Control harmony

Utility at high acceleration

Controller geometry and location

Trim control

H

As experience using the side stick was gained and modifications were

V¸

attempted to make each factor fully acceptable to the pilot, most

features included in the initial design were found to be satisfactory.

All pilots agree to the utility value of the side stick at high

acceleration; however, the location of the control in relation to the

pilot's arm position proved most critical. A modification allowed the

selection of five different positions, which provided for adjustment of

the control stick, fore or aft prior to flight, to satisfy an individual

pilot's desire. The trim control remains controversial, and further

evaluations will seek the best compromisebetween a wheel or button

control and the best location for it on the stick. In general, the

control has been most desirable on many occasions and has been used

entirely on someflights from launch to landing.

LANDING TECHNIQUES The final phase of each flight is, of course, the landing. This area has progressed from one receiving a great deal of concern and attention in the first flights to routine operation based on the experience, procedures, and techniques developed (see ref. 4).

Prior to and during the X-I_ flight program, landing simulations have been made by using the F-104 airplane. With predeterminedsettings of the lift and drag devices and the engine thrust, the lift-drag ratio is established to match that of the X-15. This experience allowed the pilots to establish geographic checkpoints andkey altitudes around the landing pattern; pilots thus become familiar with the position and timing required in the pattern by the low lift-drag ratio. At present, prior to each X-15 flight, the pilot devotes an entire F-f04 flight to approaches and landings in what is considered satisfactory preparation and practice for the landing maneuver.

Space positioning of the X-15 for a landing is shown in figure 9, which illustrates the wide range of conditions in altitude at the high key and lateral dispersionfrom the touchdown point. This figure indicates the flexibility allowed the pilot in maneuvering to a designated

CONFIDENTIAL 9

touchdown point. This flexibility is primarily attributed to several factors. The pattern is normally flown at an indicated airspeed of 300 knots, and the handling qualities, including the control-system use and the airplane responses, are considered excellent. If less sink rate is desired, the aircraft can be flown at an indicated airspeed of 240 knots for best lift-drag ratio; and, if necessary_ excess altitude can be lost at constant airspeed by use of the speed brakes. Although rates of sink average 250 feet per second and have been as high as 475 feet per second prior to landing flare, none of the pilots has considered these values to be a limiting factor in the pattern.

H

A summary of flare characteristics is shown in figures i0 and ii.

Note again the wide range of conditions that a pilot can choose to arrive at a similar landing. The flare-initiation altitude shown in figure lO has generally averaged less than 1,O00 feet but covers a wide range of airspeeds.

In figure ll_ the average vertical velocity at the flare ranges between lO0 and 180 feet per second, which is usually at a lower rate of sink than that for steady glide. This reduction is generally a result of deceleration during the approach. Aside from airspeed control, the cues that a pilot uses are all external. A landing point is chosen and the flare point is selected so that the remaining energy will carry the aircraft to the intended touchdown spot. The flare altitude is not selected from the altimeter_ but from the pilot's own estimate of the height necessary to reduce the sink rate and arrive level in proximity to the ground. It is significant that as flight progressed, the flare speeds increased, not to seek better handling qualities_ which are good throughout, but to gain more time after the flare to make configuration changes, correct trim changes, and then execute the landing at acceptable values of angle of attack, sink rate, and proximity to the intended landing point.

Pertinent touchdown parameters are presented in figures 12 and 13.

As is shown in figure 12, most landings have been accomplished with vertical velocities of less than -5 feet per second at angles of attack between 6 ° and 8 °. Ground effect_ while noted in some cases, has not been a significant factor in the pilot's analysis of the landing. In each of the last 20 landings a specific spot has been used for the intended touchdown point. In figure 13, all but four landings have been grouped within ±i_200 feet of that spot. This degree of precision is considered to be very good. The landing summary shownreveals an average slideout distance from touchdown of 5,000 to 6,000 feet. The shortest distance can be achieved by using full aft longitudinal control and flap retraction to place the greatest load on the skids_ and full deflection with speed brakes for added drag. In addition to good inherent directional characteristics on the ground, the pilot has used lateral'control inputs to provide greater load on one skid and achieve some measure of directional cont

l0 CONFIDENT IAL

In summarizing the landing information, it is considered important

to indicate that the pilot, provided an aircraft with good control and

handling qualities as represented in the X-15 in the landing pattern,

can intercept the pattern at any one of its key positions, can make

adjustments based on his experience, judgment, and reactions to the

many cues available, and can complete a satisfactory landing in proximity

to a designated landing spot with a power-off, low-lift-drag-ratio

airplane. Experience with the X-15 has included landings with various

dampers inoperative, a few recent landings using only the side-located

controller, and one recent landing with one windshield outer panel

shattered to the point of being opaque, with an attendant compromisein

H

the pilot's visibility and the landing task. These landings have been

equally satisfactory and are grouped with the other data presented.

CONCLUDING REMARKS

This summary of X-15 handling qualities has been, in general, an expression of pilot opinion, verified in many cases by the data acquired, rather than an attempt to compare with specifications. Obviously, the main concern in expanding the flight envelope to design speed and altitude has been a detailed analysis of each forward step taken so that it could be achieved safely. With these missions completed, flights can now be performed within the flight envelope with an aim to gathering handling-quality data as they compare or relate to formulating detail specifications.

The flight environment into which the X-15 has been flown has not indicated a significant change in handling-quality specifications as they are known today. In this sense the performance of the X-15 can still be related to that of certain of the century-series fighters, despite their vast performance differences. The pilot still desires an excellent control system, insists on the aircraft responding to his inputs at the rates he desires, and is displeased with undamped oscillations about any axis. Certain differences in what the pilot desires may become evident whether he is flying an X-15 or an operational fighter. When proceeding in unexplored regions in an X-15, pilots prefer having damping in roll and a high longitudinal damping, probably because it gives a feeling of security to have a solid air- plane. In the fighter, excessive damping might inhibit the ease with which a pilot can track a target. In the past, pilot preferences have been translated into design specifications regarding handling qualities.

From pilot experience, it seems apparent that many of the procedures • _ T• !,,,_ • CONFIDENTIAL ii followed in the X-15 program will be used for future hypersonic and aerodynamic reentry vehicles.

Flight Research Center National Aeronautics and Space Administration Edwards_ Calif._ November 20_ 1961 REFERENCES H l.

7 Perkins_ Courtland D._ and Hage_ Robert E.: Airplane Performance Stability and Control. John Wiley & Sons_ Inc., c. 1949.

.

Petersen, Forrest S., Rediess_ Herman A._ and Weil, Joseph: Lateral-Directional Control Characteristics of the X-15 Airplane.

NASA TM X-726 , 1962.

.

Creer, Brent Y._ Heinle_ Don,van R._ and Wingrove_ Rodney C.: Study of Stability and Control Characteristics of Atmosphere- Entry Type Aircraft Through Use of Piloted Flight Simulators.

Paper No. 59-129, Inst. Aero. Sci., Oct. 5-7, 1959- o Matranga_ Gene J.: Analysis of X-15 Landing Approachand Flare Characteristics Determined From the First 30 Flights. NASA TN D-I057 , 1961.

CONFIDENTIAL

X-15 COCKPIT

I ro Figure i

LONGITUDINAL TRIM CHARACTERISTICS

trim, DEG .8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 M Figure 2 CONFIDENTIAL

REPRESENTATIVE ALTITUDE MISSION

DYNAMIC I000 PRESSURE, PSF 500 f_ 240 x 103 ,/-APOGEE BURNOUT h- OJ I ALTITUDE, FT // \\ an=3.Sg #O'CLIMB REENTRY_ -2'2g

TURN TO

I I I I I I 0 40 80 120 160 200 240 RANGE, NAUTICAL MILES Figure 3

REACTION-CONTROL UTILIZATION

I I I I I I Ii0 5 3 5 _,PSF 5 I0 20- l L i i I I0 _, DEG -5 -_ I _ I I I I I I I 0 I0 20 30 40 50 60 70 80 90 TIME, SEC Figure 4 CONFIDENTIAL iiiiiiiiiiiii iSiiiiA|R NEiiii T!TUDE iiiiiiB! E ipiiiiiiiiii; .......................................................................................................................................................................................................................................................

............................................................................................................................................................................................... _...............................................................................................

_......................................................................................................................................................................................................_......_...........................................................................

Figure 5 REENTRY TIME HISTORY 0 °n'g 0

,e, OEG Oi , V v -

I

_4 I I I I I I I I 0 5 I0 15 20 25 30 ::55 40 TIME, SEC Figure 6 r CONFIDENTIAL

X-15 LATERAL-CONTROL UTILIZATION

M=2.5 TO 5.5 o o Oo o oJ I @ A_max, 80 o DEG o o o 0 o o 4-0 0 o o Qo°O_ ooo ° OEI 0 _0 0 o o ol#o_oaOoo@ o I °°B_# _ _ I o I I I 5 I0 15 20 0 25 30 Pmax, DEG/SEC Figure 7 SUMMARY, OF X-15 LONGITUDINAL HANDLING QUALITIES M = 2.5 TO 5.5, q=lO0 TO 1,400 PSF o SATISFACTORY (P.R.=I TO &5) e UNSATISFACTORY (PR.= 3.5 TO 6.5) PILOT RATING 6.5 3.5 --AMES CRITERIA SATISFACTORY RADIANS 3 _n, SEG 0 @ LUNS;TISFACToRY I I I I I I I I 0 .2 .4 .6 .8 1.0 1.2 1.4 16 Figure 8 CONFIDENTIAL SUMMARY OF X-15 LANDING PATTERN i ...... • LATERAL DISTANCE FROM TOUCHDOWN, FT 40 _ TYPICAL APPROACH (FLIGHT 1-10-19) RANGE OF FLIGHT DATA

ao _

ALTITUDE, FT 0 j 20 0 20 40xlo 3 LONGITUDINAL DISTANCE FROM TOUCHDOWN, FT Figure 9

X-15 FLARE-INITIATION ALTITUDE

(W/S)ov =73 PSF PREDICTED 1600 0 1.4 CONSTANT g 0 o FLARE / 0 0 // 0 ALTITUDE, / O J FT 0 o 0 ,.-,'_ 0 ___o_-o--- o_ o o _ 0 0 0 0 I I t I I 240 260 280 300 320 340 INDICATED AIRSPEED, KNOTS Figure i0 2L CONFIDENTIAL X-15 GLIDE CONDITIONS AT FLARE INITIATION (w/S)Qv : 7.3 PSF sSSIg TRIM 160 o .o" o (9 _,S _* 0 0 , s _SO 0 (9 0 CP 120 _..s o o (9 VERTICAL O _ (9 0 0 0 (9 VELOCITY, ),,,_ 0 (9 (9 (9 OJ o o o I o FPS 80- o o 0(9 o o 4O ' I I I I I I I I I 240 260 280 :.'.300 :320 :340 INDICATED AIRSPEED, KNOTS Figure ii X-15 TOUCHDOWN PARAMETERS (W/S)av = 73 PSF TOUCHDOWN o o VERTICAL -5 o _ o 9) VELOCITY, o

-,of o

FPS o (_/_'° o_07 0 _ UP 12

o TR,M

TOUCHDOWN 8 o _8-.

_o_.

0080 o'--.

ANGLE OF ATTACK, o o_ -..

Oo _6 Oo DEG 4 o O i I I F 140 160 180 200 220 TOUCHDOWN INDICATED AIRSPEED, KNOTS Figure 12 18 CONFIDENTIAL X-15 TOUCHDOWN AND SLIDEOUT DISTANCES LONG 4xlO 3 o oOO ° TOUCHDOWN 0 o% o DISPERSION, cp LONGITUDINAL } o / FT o o SHORT 4 ' ' ' ' ' ' ' J BxlO 3 O0 O0 0 SLIDEOUT, O FT C i i i i

,6o ,8o 260 2_,o

TOUCHDOWN INDICATED AIRSPEED, KNOTS Figure 13 NASA-Langley, 1962 H-270 NASA TM X-715 NASA TM X-715 National Aeronautics and Space Administration.

National Aeronautics and Space Administration.

RF.SUM_ OF HANDLING QUALITIES OF THE X-15 I. White, Robert M. RESUM]_ OF HANDLING QUALITIES OF THE X-15 I. White, Robert M, - -, II. Robinson, Glenn H_ II. Robinson, Glenn H. AIRPLANE. Robert M. White, Glenn H. Robinson, AIRPLANE. Robert M. White, Glenn H. Robinson, III. Matranga, Gene J.

III. Matranga, Gene J. and Gene J. Matranga. March 1962. 18p.

and Gene J. Matranga. March 1962. 18p.

IV. NASA TM X-715 IV. NASA TM X-715 (NASA TECHNICAL MEMORANDUM X-715 (NASA TECHNICAL MEMORANDUM X-715 (Initial NASA distribution" (Initial NASA distribution: (Title, E (Title, l: 3, Aircraft; . _ "_ 3, Aircraft; A summary of handling qualities is presented as A summary of handling qualities is presented as 50, Stability and control.)

assessed from pilot opinion and flight data. Segments assessed from pilot opinion and flight data. Segments 50, Stability and control.). :-_ of the flight profile which were evaluated include the of the flight profile which were evaluated include the launch, climbout, semiballistic flight, atmosphere launch, climbout, semibailistic flight, atmosphere entry, and landing. Longitudinal controllability is entry, and landing. Longitudinal controllability is compared with results from current studies of compared with results from current studies of reentry-type vehicles.

reentry-type vehicles.

NASA NASA Copies obtainable from NASA, Washington Copies obtainable from NASA, Washington NASA TM X-715 NASA TM X-715 National Aeronautics and Space Administration.

National Aeronautics and Space Administration.

I. White, Robert M. RESUMI_, OF HANDLING QUALITIES OF THE X-15 I. White, Robert _I:_ ,_, RESUM_ OF HANDLING QUALITIES OF THE X-15 II. Robinson, Gleni_ _H_, ® If. Robinson, Glenn H. AIRPLANE. Robert M. White, Glenn H. Robinson, AIRPLANE. Robert M. White, Glenn H. Robinson, III. Matranga, Gene J.

Ill. Matranga, Gene J. and Gene J. Matranga. March 1962. 18p.

andGene J. Matranga. March 1962. 18p.

IV. NASA TM X-715 IV. NASA TM X-715 (NASA TECHNICAL MEMORANDUM X- (NASA TECHNICAL MEMC (Initial NASA distribution: (Initial NASA distribution: (Title, Unclassifiec (Title, Unclassifie 3, Aircraft; 3, Aircraft; A summary of handling qualities is presented as A summary of handling qualities is presented as 50, Stability and control.) 50, Stability and control.)

assessed from pilot opinion and fl.ight data. Segments assessed from pilot opinion and flight data. Segments of the flight profile which were evaluated include the of the flight profile which were evaluated include the launch, climbout, semiballistic flight, atmosphere launch, climbout, semiballistic flight, atmosphere entry, and landing. Longitudinal controllability is entry, and landing. Longitudinal controllability is compared with results from current studies of compared with results from current studies of reentry-type vehicles.

reentry-type vehicles.

NASA NASA Copies obtainablefrom NASA, Washington ;Copies obtainablefrom NASA, Washington