Research Memorandum

NFIDENTIAL

NACA

RESEARCH MEMORANDUM

FLIGHT INVESTIGATION OF AN AILERON AND A SPOILER ON A WING

OF THE X-3 AIRPLANE PLAN FORM AT MACH NUMBERS FROM 0.5 TO 1.6 C? By Roland D. English

Langley Aeronautical Laboratory Langley Field, Va.

: o .. CLASSIFIED DOCUMENT This material contains information affecting the National Defense of the United States within the meaning 0, of the espionage laws, Title 18, U.S.C., Secs. 793 and 794, the transmission or revelation of which in any manner to an unauthorized person is prohibited by law. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WASHINGTON June 18, 1954 NACA EM L54D26a CONFIDENTIAL

NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

RESEARCH MEMORANDUM

FLIGHT INVESTIGATION OF AN AILERON AND A SPOILER ON A WING

OF THE X-3 AIRPLANE PLAN FORM AT MACH NUMBERS

FROM 0.7 TO 1.6

By Roland D. English

SUMMARY

A flight investigation has been made to determine the rolling effectiveness and drag of several controls on a tapered wing which was uriswept at the 75-percent-chord line (x-3 airplane plan form). The investigation was made by the use of rocket-propelled models in free flight over a Mach number range from 0.5 to 1.6. The results indicate that the rolling effectiveness was slightly higher for a 0.25-chord aileron deflected 50 than for a 0.02-chord trailing-edge spoiler, except in the transonic region. In the subsonic range the difference was negligible. At supersonic speeds, the difference in rolling effectiveness was near the limits of experimental accuracy, but because of the consistency of the variation over the supersonic range, it is believed to be significant. Drag coefficient was higher for the wing with spoilers than for the wing with aileron, but the difference is believed to be largely due to a difference in the airfoil sections of the two wings. There was no appreciable difference in either rolling effectiveness or drag coefficient for the spoiler mounted flush with the wing surface and raised 0.01 chord above the wing surface.

INTRODUCTION

An investigation has been made in free flight to determine the rolling effectiveness and drag of two types of controls on a tapered wing which was unswept at the 75-percent-chord line (x-3 airplane plan form). The investigation was made with rocket-propelled models in free flight over a Mach number range from 0.5 to 1.6. The controls tested included a 0.25-chord aileron deflected 50 and a 0.02-chord spoiler,

CONFIDENTIAL 2 CONFIDENTIAL NACA RN L54D26a both extending over the outboard 30 percent of the semispan. Tests were made with the spoiler mounted flush with the wing surface and with a 0.01-chord gap between the spoiler and the wing surface. This paper presents the results of the investigation.

SYMBOLS b wing span, ft c local wing chord, ft c 1 section lift coefficient

CD drag coefficient based on exposed wing area (1.04 sq ft)

G shear modulus, lb/sq. in.

J torsional constant of free-stream airfoil section, in.

M Mach number p rolling velocity, rad/sec

R Reynolds number based on mean exposed wing chord of 0.626 ft

V model flight-path velocity, ft/sec pb/2V wing-tip helix angle, rad

angle of attack, deg

B deflection of each aileron, deg

angle of attack of wing-aileron section equivalent to unit j/dB aileron deflection, dc dc/dcr.

MODELS AND TESTS

The models tested consisted of two wings on a pointed cylindrical body which was equipped with a tail that was free to roll relative to the body so as to keep the models near zero angle of attack and zero

CONFIDENTIAL NACA RM L54D26a CONFIDENTIAL 3 angle of yaw without affecting the rolling effectiveness of the controls. The wings had an aspect ratio of 3.04, a taper ratio of 0.40, a semispan of 1.01I feet, an exposed area of 1.04 square feet, and were unswept at the 75-percent-chord line. The maximum thickness of the airfoil sections was 0.045c. The wing of model 1 had a sharp trailing edge, but, because of the impracticability of mounting a trailing-edge spoiler on a full- scale airplane wing with sharp trailing edge, the basic airfoil section was modified on models 2 and 3 to give a blunt trailing edge 0.02c thick. Model 1 was equipped with a 0.25c sealed flap-type aileron and models 2 and 3 with 0.02c spoilers located at the trailing edge of both wings. On model 2 the spoiler was attached directly to the wing surface, whereas on model 3 the spoiler was raised O.Olc above the wing surface. The aileron deflection (50) of model 1 was selected so as to make the dis- placement of the aileron trailing edge from the chord plane approximately equal to the height of the spoilers on models 2 and 3. Both the ailerons and the spoilers extended over the outboard 30 percent of the semispan. All wings were made of solid aluminum alloy. The geometric details and dimensions of the models are given in the photographs of figure 1 and the sketches of figure 2.

The models were propelled to a Mach number of 1.6 by a two-stage rocket propulsion system. All test data were recorded during a period of free flight following burnout of the second propulsion stage. Rolling velocity was measured by special radio equipment (spinsonde) and model flight-path velocity and range coordinates by means of radar. Atmos- pheric data were recorded immediately before the model flights by radio- sonde and were used with the model test data to calculate the variation of the rolling-effectiveness parameter pb/2V and drag coefficient CD with Mach number. The range of test Reynolds numbers is given in figure 3. A more detailed description of the test technique is presented in references 1 and 2.

From previous experience and mathematical analysis it is estimated that the test data are accurate within the following limits:

Subsonic Supersonic

pb/2V ±0.004 ±0.002

CD ±0.004 ±0.002 M ±0.01 ±0.01

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DISCUSSION OF RESULTS

Rolling Effectiveness

Comparison of aileron and spoiler.- The variation of the rolling- effectiveness parameter pb/2V with Mach number is presented in figure 4. Rolling effectiveness was corrected by the method of reference 3 for the small wing-incidence errors resulting from construction tolerances. No correction was made for the effects of moment of inertia in roll, since reference 1 shows this correction to be small. It may be seen from figure !i that the pb/2V curve for the aileron model is slightly higher than those of the spoiler models except in the transonic region. In the subsonic range, the difference is negligible. At supersonic speeds, the difference in rolling effectiveness is near the limits of experimental accuracy, but because of the consistency of the variation over the supersonic range, it is believed to be significant. It should be noted that the wing trailing edge of the aileron model was sharp whereas the trailing edges of the wings of the spoiler models were blunt. Refer- ence Ii- indicates that blunting the trailing edge of the wing increases aileron control effectiveness slightly. If the trailing-edge thickness of the aileron model in the present investigation were increased to that of the spoiler models, the difference in rolling effectiveness for the aileron and the spoiler would probably be greater. There was essentially no difference in the rolling effectiveness of the spoiler when mounted flush with the wing surface and raised O.Olc above the wing surface.

Aeroelastic effects.- The effects of aeroelasticity on the rolling effectiveness of the aileron model are shown in figure 5 by a comparison of the rolling effectiveness of a solid aluminum-alloy wing and a solid magnesium wing with rigid-wing rolling effectiveness. Solid magnesium was selected arbitrarily as a means of extending the range of structural characteristics for which rolling effectiveness is presented. The method of reference 5 was used to obtain the rolling effectiveness of the rigid and magnesium wings and to correct the rolling effectiveness of the aluminum-alloy wing to sea-level conditions. The data of figure 5 are cross-plotted in figure 6 to give the variation of rolling effectiveness with the structural-stiffness parameter c/GJ at various Mach numbers. The curves of figure 6 may be used to obtain an estimate of the rolling effectiveness of a wing of the same plan form with any value of &4/GJ that falls within the range considered. The method of reference 5 is not applicable to spoilers, so the effects of aeroelasticity on spoiler rolling effectiveness were not determined.

Comparison with theory.- Rigid-wing rolling effectiveness is compared with various theoretical calculations in figure 7. Theoretical rolling effectiveness was calculated by using the zero-aspect-ratio theory of

CONFIDENTIAL NACA EM L54D26a CONFIDENTIAL 5 reference 6 at subsonic speeds, the linearized three-dimensional theory of reference 7 at supersonic speeds, and the strip theory of reference 3 at both subsonic and supersonic speeds. Good agreement is shown between experiment and both three-dimensional and strip theories at supersonic speeds. Experiment agrees fairly well with strip theory in the subsonic region also, but is underestimated by about 20 percent by zero-aspect- ratio theory. However, it should be noted that in the strip theory and zero-aspect-ratio theory calculations, theoretical values of a,, were used which are believed to be considerably lower for wings of low aspect ratio at subsonic speeds.

Drag Coefficient

The variation of the drag coefficient CD with Mach number ±s presented in figure 8 for all models. The drag coefficient of the body alone equipped with free-rolling tail is. included in the figure for reference. The drag coefficient of the wing with spoilers is considerably higher than that of the wing with ailerons except in the transonic region. However, reference 4 shows that blunting the trailing edge of the wing increases drag appreciably. The fact that the spoiler models had blunt trailing edges is believed to account for the larger part of the difference in the drag of the aileron model and spoiler models. There is no appreciable difference in the drag coefficient of the wing with spoiler mounted flush and with spoiler raised 0.Olc above the wing surface.

CONCLUSIONS

From the results of a free-flight investigation at essentially zero angle of attack and zero angle of yaw of the rolling effectiveness and drag of an aileron and a spoiler on a tapered wing which was unswept at the 75-percent-chord line (X_3 airplane plan form) the following conclusions may be drawn:

1. The rolling-effectiveness curve for a 25-percent-chord aileron deflected 50 is slightly higher, except in the transonic region, than that of a 2-percent-chord trailing-edge spoiler of the same span. In the subsonic range, the difference is negligible. At supersonic speeds, the difference in rolling effectiveness is near the limits of experimental accuracy but because of the consistency of the variation over the supersonic range, It is believed to be significant. There was essen - tially no difference in the rolling effectiveness of the spoiler when mounted flush with the wing surface and raised O.Olc above the wing surface.

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2. The drag coefficient is higher for the wing with spoilers than for the wing with ailerons except in the transonic region. However, the wing with spoilers had a blunt trailing edge whereas the trailing edge of the wing with ailerons was sharp. This difference in airfoil section is believed to have caused most of the difference in drag. Drag coefficient was essentially the same for the spoiler with bottom edge flush with the wing surface and with bottom edge 0.01 chord above the wing surface.

Langley Aeronautical Laboratory, National Advisory Committee for Aeronautics, Langley Field, Va., April 16, 1954.

REFERENCES

1. Sandahi, Carl A., and Marino, Alfred A.: Free-Flight Investigation of Control Effectiveness of Fall-Span 0.2-Chord Plain Ailerons at High Subsonic, Transonic, and Supersonic Speeds to Determine Some Effects of Section Thickness and Wing Sweepback. NACA EM L7D02, 1917.

2. Pitkin, Marvin, Gardner, William N., and Curfman, Howard J., Jr.: Results of Preliminary Flight Investigation of Aerodynamic Charac- teristics of the MACA Two-Stage Supersonic Research Model EM-i Stabilized in Roll at Transonic and Supersonic Velocities. MACA EM L6J23, 1947.

3. Strass, H. Kurt, and Marley, Edward T.: Rolling Effectiveness of All-Movable Wings at Small Angles of Incidence at Mach Numbers From 0.6 to 1.6. MACA EM L51H03, 1951-

Ii-. Fields, E. M., and Strass, H. Kurt: Free-Flight Measurement at Mach Numbers From 0.7 to 1.6 of Some Effects of Airfoil-Thickness Distri- bution and Trailing-Edge Angie on Aileron Roiling Effectiveness and Drag for Wings With 0 0 and 150 Sweepback. MACA EM L51G27, 1951-

5. Strass, H. Kurt, and Stephens, Emily W.: An Engineering Method for the Determination of Aeroelastic Effects Upon the Rolling Effec- tiveness of Ailerons on Sweptback Wings. MACA EM L53H14, 1953.

6. DeYoung, John: Spanwise Loading for Wings and Control Surfaces of Low Aspect Ratio. MACA TN 2011, 1950.

7. Tucker, Warren A., and Nelson, Robert L.: The Effect of Torsional Flexibility on the Rolling Characteristics at Supersonic Speeds of Tapered Unswept Wings. MACA Rep. 972, 1950.

CONFIDENTIAL NACA EM L74D26a CONFIDENTIAL

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NACA RN L54D26a CONFIDENTIAL 11

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0 .L. .6 .8 1.0 1.2 1.4 1.6 M

Figure 3.- Variation of test Reynolds numbers with Mach number. Reynolds numbers based on mean exposed wing chord, 0.626 foot.

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12 CONFIDENTIAL NACA EM L54D26a

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CO1FIDTIAL

NACA BM L54D26a CONFIDENTIAL 15

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.10

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.02

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Figure 8.- Variation of drag coefficient CD with Mach number.

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