Cooney, T V

Mcgowan, William A

English

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RM L9128a 
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RESEARCH MEMORANDUM 
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TIME HISTORIES OF LOADS AND DEFORMATIONS ON A 
B-45A AIRPLANE IN TWO AILERON ROLLS

By I. V. Cooney and William A. McGowan 
Langley Aeronautical Laboratory 	 GROUP 4 
A ::	 Langley Air Force Base, Va.	 Downgraded at 
FILM	 nterb1s affft  
Uopy CassUication Changed to 
CLASSIFIED UTMEN 
This do	 ent contains olaaaldhed information S TtflI
 al""ting the National Defense of the Unit d 
States within the wnaalng of
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revelation of itscontents in any manaer to an Da e	 3 
oneothorized person Is prohibited by law. 
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MAR 3	 14_¶2 o 
of 
civiloan 	 weternpioyeet. of the Federal 
Governan-st	 who have a legitimate 	 Interest 
therein	 and to Jolted Statea citizens of known 
loyalty and discretion who of necessity moat be 
ofoCrned throob.
NATIONAL ADVISORY COMMITTEE 
FOR AERONAUTICS 
WASHINGTON 
November 8, 1949 \iIIIIIIiiJI 
By 
k11?A I
 
UNCLASSIFIED 
https://ntrs.nasa.gov/search.jsp?R=19930085994 2020-06-17T16:16:27+00:00Z
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NATIONAL ADVISORY COMt{tTl'EE FOR
	
Y. 
RESEARCH MEMORANDUM 
TIME HISTORIES OF LOADS AND DEFORMATIONS ON A 
B-45A AIRPLA1E IN TWO AILERON ROLLS 
By T. V. Cooney and William A. McGowan 
Loads measured. on the horizontal tail, vertical tail, and wing 
and the aeroelastic distortions of elevators, stabilizers, and fuselage 
of a B-45A airplane in a right and a left roll at a Mach number of 0.60 
and an altitude of 15,000 feet are presented. The data are given in 
time-history form.
INTRODUCTION 
A B-5A airplane has been made available to the NACA for a tail-. 
loads investigation. The airplane has been instrumented with strain 
gages for measurements of the horizontal-tail, vertical-tall, and wing 
loads and with additional instruments for measurement of the deforma-
tion which occurs in the elevators, stabilizers, and fuselage due to 
aerodynamic and inertia loads. 
Some immediate results obtained from the first flight, which was 
primarily a pilot familiarization and instrument check flight, are 
presented in this paper. Loads on the horizontal tail, vertical tail, 
and wing and the structural deformation of stabilizers, elevators, and 
fuselage during right and left aileron rolls with rudder fixed at an 
altitude of 15,000 feet and a Mach number of 0.60 are presented in 
time-history form. Time histories of a steady-flight run, two pull-ups, 
and a turn have previously been reported in reference 1. 
Classification Changed to GONPOENTIAL
 
thorit 
'ate [MAR 3i9M
A
2	 NACA RM 19128a 
SYMBOLS 
Symbols used in this paper are defined as follows: 
M	 Mach number 
hp	 pressure altitude 
g	 acceleration due to gravity, 32.2 feet per second per 
second 
Up loads on the horizontal stabilizers, elevators, and wing are 
considered positive. Positive loads on the vertical tail act to the 
right when looking forward. Other sign conventions used are defined 
in the figures.
APPARATUS AND TESTS 
The airplane used for this Investigation is a B-45A (No. 7021). 
Figure 1 is a three-view drawing of the airplane showing the approxi-
mate locations of the load and deflection-measuring devices. 
Standard NACA photographic recording instruments are used to 
measure airspeed and altitude, rolling, pitching, and yawing velocities, 
sideslip angle, accelerations, control forces, and control positions. 
The normal, transverse, and longitudinal accelerations are measured at 
the airplane center of gravity and at fuselage station 71 14 (approxi-
mately the one-quarter chord of the horizontal tail). Measurements of 
normal accelerations are also made at the midsemnlspan and tip of both 
horizontal stabilizers. 
The airspeed. boom is mounted at the left wing tip with the air-
speed head approximately 1 chord length ahead of the leading edge. 
The results of a flight calibration of the airspeed system for 
position error and the analysis of available data for a similar 
installation Indicate that Mach number is correct to ±0.01. The 
sideslip-angle recorder Is mounted on a boom extending approxi-
mately 1 chord length ahead of the right wing at the tip. 
Electrical resistance strain gages are installed on each spar 
for shear and bending-moment measurements at stations 18 and 114 on 
the horizontal and vertical tails, respectively, and at station 71 on 
the wing. In addition, strain gages Installed, on the elevator and 
rudder hinges and torque tubes permit measurements of loads and torques 
on these control surfaces. Twist bars installed in the horizontal
NACA RM L9128a
	 3 
stabilizers are used to measure the twist of the stabilizer niidsemi-
span and tip with respect to the root. Control—position transmitters 
mounted at the root and tip of each elevator are used to measure the 
elevator twist. The transmitters are wired so as to give no response 
when the elevator is deflected without twisting. In flight, these 
measurements refer to twist of the elevator relative to the stabilizer. 
The right and left elevators are warped at the tip 1.00 and 1.50
 trailing 
edge up, respectively. To obtain total elevator twist, the elevator 
built—in twist must be added to the flight measurements. Additional 
control—position transmitters installed at the root of the elevator are 
used to measure the elevator position. The positions of the tabs, rudder, 
and ailerons are also measured by control—position transmitters. 
An optigraph mounted at the rear spar of the wing (fuselage 
station 423) is used to record the vertical motion of small lights 
positioned in the fuselage at the approximate location of the front. 
and rear spare of the horizontal tail (fuselage stations 699 and 759). 
From this installation a time history of the structural deflection of 
the rear portion of the fuselage can be obtained. A —seconâ time 
pulse was used to correlate data from all recording instruments. 
The data reported herein were obtained in right and left rolls at 
an altitude of 15,000 feet and M = 0.60. 
RESULTS AND DISCUSSION 
The loads presented are aerodynamic loads. The estimated reading 
accuracies for the quantities measured are shown in table I. 
Presented in figure 2 are time histories of quantities measured. 
In the right roll with the airplane in the clean condition at a Mach 
number of approximately 0.60 at 15,000 feet. Time histories of 
measurements made during a left roll at approximately the same altitude 
and Mach number are shown in figure 3. There was no appreciable varia-
tion in airspeed or altitude during either maneuver. 
It can be seen from figure 2 that the horizontal—tail—load 
dissymmetry during a right roll is small, the greatest being 400 pounds 
more down load on the left tail. The horizontal—tail load varies 
between 2700 pounds and 3800 pounds in the down direction. Elevator 
loads are up and small and are less than 400 pounds. 
At the start of the ran the airplane is in steady 20 left side-
slip, and at the time of greatest vertical—tail load the sideslip angle 
- CONFflNTIL
4	 NACA RM L9128a 
A	 & 
is approximately zero. The maximum rate of roll is 0.14.6 radian per 
second. The elevator angles are practically constant at 2.00 down 
during the maneuver. 
The vertical-tail load in the right roll is small. The fin load 
is 1420 pounds to the right at the start of the run with a load 
of 950 pounds to the left occurring at the time of zero sideslip. The 
rudder load. is to the left throughout the maneuver and is always less 
than 200 pounds. The rudder angle Is zero. 
Right and left wing loads are presented. The differential rigging 
of the ailerons accounts in part for the unsymmetrical appearance of 
the curves. Maximum total aileron deflection for this maneuver (sum of 
right and left deflections). is approximately 180. The maximum total 
aileron angle available is 450. 
Right and left stabilizers twisted approximately 0.20 nose down 
while the 0.16-inch tail-down bending of the fuselage at station 699 
was reduced 0.03 inch during the roll. Measured twist of the left 
elevator is 0.750 trailing edge up while the twist measured on the 
right elevator is 1.50 trailing edge up. The difference in measured 
twist of right and left elevators in flight may be attributed to the 
elevator built-in twist. 
Figure 3 shows that the greatest horizontal-tail-load dissymmetry 
in left roll is 750 pounds. At the same time the sideslip angle 
increased from 1.70 left to 4.4 left. Total horizontal-tail loads 
increased positively from 3800 pounds down to 2000 pounds down. 
Elevator loads are less than 14.00 pounds in the up direction. 
The maxiinuni rate of roll In the left roll is 0.56 radian per 
second. The elevator angles are constant at approximately 2.00 down. 
The greatest total aileron angle is 230. 
It is seen that the increment in fin load is 1600 pounds with a 
maximum load to the right of 2000 pounds, which occurs at approximately 
the time of peak sideslip. The rudder load is small and varies 
from 100 pounds to the left to 40 pounds to the right. The rudder 
angle is zero. 
The right and left wing loads are approximately symmetrical about 
a mean which follows the trend of the center-of-gravity normal-
acceleration curve. Stabilizer and elevator twists and fuselage defleo-
tion are similar to those shown in figure 2. This similarity is to be 
expected since horizontal-tail loads in both right and left rolls were 
found to be comparable.
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NACA RM L9128a	 5 
The results obtained indicate that loads on the fin and rudder of 
the test airplane are small during right and left aileron rolls with 
rudder fixed at M = 0.60 and an altitude of 15,000 feet. The incre-
ment in sideslip angle of 2.70 was obtained using a total aileron 
deflection of approximately one—half the available aileron travel. The 
greatest load dissymmetry on the horizontal tail occurred during the 
left roll where the right tail carried 750 pounds more down load, than 
the left. 
Langley Aeronautical Laboratory 
National Advisory Comniittee for Aeronautics 
Langley Air Force Base, Va. 
1. Aiken, William S., Jr., and Wiener, Bernard : Time Histories of 
Horizontal-Tail Loads on a Jet—Powered Bomber Airplane in Four 
Maneuvers. NACA RM L91116a, 1949. 
cp	 pEINTI1 •;i
	 -
6	 NACA RM L9128a 
TABLE I 
ESTIMATED READING ACCURACIES FOR MEASURED QUANTITIES 
Center—of—gravity normal acceleration, g units ......... ±0.03 
Tail normal acceleration, g units 	 ............... ±0.05 
Tail transverse acceleration, g units	 ............. ±0.01 
Elevator positions,	 deg	 .................... ±.0.25 
Aileron positions,	 deg	 ..................... ±0.10 
Rudder positions,	 deg	 ....................... ±0.10 
Sideslip angle,	 deg	 ...................... ±0.10 
Pitching acceleration, radians/sec 2	 ............... ±0.01 
Rolling velocity, radians/sec 	 ................. ±.o.008 
Yawing velocity, radians/sec	 .................. ±0.01 
Total horizontal—tail aerodynamic load, lb ........... ±.i60 
Stabilizer aerodynamic load, lb (each stabilizer) 	 ........±lli.O 
Elevator aerodynamic load, lb (each elevator)
	
.' ........ ±60 
Total vertical—tail aerodynamic 1oad,lb ............ ±130 
Fin aerodynamic load, lb ..................... ±100 
Rudder aerodynamic load, lb 	 .................. t30 
Wing aerodynamic load, lb (each wing) 	 ............. ±1000 
Stabilizer twist at tip, 	 deg ................... ±0.017 
Stabilizer twist at midsentLepan, deg .............. ±0.001 
Elevator twist (uncorrected for stabilizer twist), deg ..... ±0.07 
Fuselage bending deflection, in . 	 .	 .	 .	 .	 .	 .	 .	 .	 .	 .	 .	 .	 . .	 .	 .	 ±0.03 
Mach number	 .......................... ±0.01
NACA PM L9128a
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locations of strain-gage bridges and deflection-measuring devices.
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NACA RM L9128a
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Figure 3.- time histories of measured quantities during a left roll. 
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'end of record____ 
.2 iIIIII.	 'Trji'_III_I /	 J	 4 Q/ OWfl	 Tire,  sec 
Figure 3 . - Concluded. 
NACA-Langley - 11-8-49 - 275 


Time histories of loads and deformations on a B-45A airplane in two aileron rolls

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