NASA/TP—2013–218036

Effectiveness of a Wedge Probe to

Measure Sonic Boom Signatures

in a Supersonic Wind Tunnel

Floyd J. Wilcox, Jr., and Alaa A. Elmiligui

Langley Research Center, Hampton, Virginia

August 2013
NASA STI Program . . . in Profile

Since its founding, NASA has been dedicated to the 

advancement of aeronautics and space science. The 

NASA scientific and technical information (STI) 

program plays a key part in helping NASA maintain 

this important role. 

The NASA STI program operates under the 

auspices of the Agency Chief Information Officer. 

It collects, organizes, provides for archiving, and 

disseminates NASA’s STI. The NASA STI 

program provides access to the NASA Aeronautics 

and Space Database and its public interface, the 

NASA Technical Report Server, thus providing one 

of the largest collections of aeronautical and space 

science STI in the world. Results are published in 

both non-NASA channels and by NASA in the 

NASA STI Report Series, which includes the 

following report types: 

 TECHNICAL PUBLICATION. Reports of 

completed research or a major significant phase 

of research that present the results of NASA 

Programs and include extensive data or 

theoretical analysis. Includes compilations of 

significant scientific and technical data and 

information deemed to be of continuing 

reference value. NASA counterpart of peerreviewed formal professional papers, but 

having less stringent limitations on manuscript 

length and extent of graphic presentations. 

 TECHNICAL MEMORANDUM. Scientific 

and technical findings that are preliminary or of 

specialized interest, e.g., quick release reports, 

working papers, and bibliographies that contain 

minimal annotation. Does not contain extensive 

analysis. 

 CONTRACTOR REPORT. Scientific and 

technical findings by NASA-sponsored 

contractors and grantees. 

 CONFERENCE PUBLICATION. 

Collected papers from scientific and 

technical conferences, symposia, seminars, 

or other meetings sponsored or cosponsored by NASA. 

 SPECIAL PUBLICATION. Scientific, 

technical, or historical information from 

NASA programs, projects, and missions, 

often concerned with subjects having 

substantial public interest. 

 TECHNICAL TRANSLATION. 

English-language translations of foreign 

scientific and technical material pertinent to 

NASA’s mission. 

Specialized services also include organizing 

and publishing research results, distributing 

specialized research announcements and feeds, 

providing information desk and personal search 

support, and enabling data exchange services. 

For more information about the NASA STI 

program, see the following: 

 Access the NASA STI program home page 

at http://www.sti.nasa.gov

 E-mail your question to help@sti.nasa.gov

 Fax your question to the NASA STI 

Information Desk at 443-757-5803 

 Phone the NASA STI Information Desk at 

443-757-5802 

 Write to: 

 STI Information Desk 

 NASA Center for AeroSpace Information 

 7115 Standard Drive 

 Hanover, MD 21076-1320 
NASA/TP—2013–218036

Effectiveness of a Wedge Probe to

Measure Sonic Boom Signatures

in a Supersonic Wind Tunnel

Floyd J. Wilcox, Jr., and Alaa A. Elmiligui

Langley Research Center, Hampton, Virginia

National Aeronautics and

Space Administration

Langley Research Center

Hampton, Virginia 23681–2199

August 2013
The use of trademarks or names of manufacturers in this report is for accurate reporting and does

not constitute an official endorsement, either expressed or implied, of such products or manufacturers by the National Aeronautics and Space Administration.

Level of review: This material has been technically reviewed by a committee of peers.

Available from:

NASA Center for AeroSpace Information

7115 Standard Drive

Hanover, MD 21076–1320

443-757-5802
Summary

A wind tunnel investigation was conducted in the Langley Unitary Plan Wind Tunnel (UPWT) to

determine the effectiveness of a wedge probe to measure sonic boom pressure signatures. A generic

business jet model at a constant angle of attack and at a single model to probe separation distance

was used to generate a sonic boom signature. Sonic boom pressure signatures were acquired with

both a wedge probe and a slender conical probe for comparison. The test was conducted at a

Mach number of 2.0 and a free-stream unit Reynolds number of 2 million per foot. The results

showed that the wedge probe was not effective in measuring the sonic boom pressure signature of

the aircraft model because the spatial separation of three measured pressures on the wedge probe

violated an assumption in the development of the wedge probe data reduction equations that the

entire probe is in a uniform flow field.

Introduction

Experimental research to measure sonic boom pressure signatures of aircraft in wind tunnels has

been conducted since the 1950s using a variety of techniques (ref. 1–9). Through the years, the

technique that used slender conical probes became the predominate standard for measuring sonic

boom pressure signatures. Because slender conical probes only measure local static pressure, reference 10 described the development of a wedge probe that could not only determine local static

pressure but also stagnation pressure, Mach number, and flow angularity in the flow field of an

aircraft. Reference 10 presented the results of a wind tunnel test using the wedge probe and stated

that the probe worked well in the free-stream flow; however, wind tunnel problems during the test

prevented the acquisition of sonic boom pressure signatures of an aircraft model. In the late 2000s,

another similar but larger wedge probe was fabricated and tested in both a wind tunnel and in

flight as described in reference 11. The wind tunnel test of the second wedge probe did not measure

the sonic boom signature of an aircraft model but rather measured the pressure signature created

by a disturbance bump mounted to the tunnel sidewall. To date, the sonic boom signature of an

aircraft model has not been measured in a wind tunnel using a wedge probe. In the present study,

a wind tunnel test was conducted to investigate the effectiveness of a wedge probe to measure sonic

boom pressure signatures.

A wind tunnel investigation was performed in the Langley Unitary Plan Wind Tunnel (UPWT)

to measure the sonic boom pressure signature of an aircraft model using both the wedge probe

described in reference 11 and a slender conical probe for comparison. The sonic boom pressure

signature was generated with an existing generic business jet model. The investigation was conducted as part of a wind tunnel test that studied the ability of a slender conical probe to measure

sonic boom signatures while continuously moving the aircraft model past the probe as described in

reference 12. The tests were conducted at a Mach number of 2.0 and at a free-stream unit Reynolds

number of 2 million per foot. The sonic boom pressure signatures were obtained with the model

at a single angle of attack (≈ 2.3

◦

) and at a model nose to survey probe (wedge or slender conical)

separation distance of 13.5 in.

Nomenclature

Abbreviations and Acronyms

AOA angle of attack, deg

ID inside diameter

NF normal force, lbf

1
OD outside diameter

PM pitching moment, in·lbf

PRT platinum resistance thermometer

psfa pound-force per square foot absolute (lbf/ft2)

psfd pound-force per square foot differential (lbf/ft2)

SLSLE straight-line segmented leading edge

UPWT Unitary Plan Wind Tunnel

Symbols

h distance from model nose to survey probe (wedge or conical) measured perpendicular

to tunnel sidewall (see figure 2b and 4c), in.

M Mach number

p free-stream static pressure, psfa

p0 free-stream stagnation pressure, psfa

p03 measured stagnation pressure behind normal shock on wedge probe upper surface

(see figure A1), psfa

p04 measured stagnation pressure ahead of wedge probe oblique shock and behind normal

shock (see figure A1), psfa

p1 computed static pressure ahead of wedge probe (see figure A1), psfa

pref reference probe pressure, psfa

q free-stream dynamic pressure, psfa

Re free-stream unit Reynolds number × 10−6, ft−1

T0 free-stream stagnation temperature, ◦F

v aircraft model longitudinal speed during continuous sweep runs, in/s

α angle of attack, deg

∆p measured differential pressure between survey probe and reference probe or the differential between the computed static pressure ahead of the wedge probe and the

measured reference probe pressure (p1 − pref ), psfd

(∆p/pref )avg average sonic boom pressure signature parameter where ∆x ≤ 21.25 in.

(∆p/pref )cor corrected sonic boom pressure signature parameter (see equation 1)

(∆p/pref )unc uncorrected sonic boom pressure signature parameter

∆x distance from model nose to survey probe orifices or wedge probe leading edge measured parallel to tunnel sidewall (see figure 2b and 4c), in.

γ ratio of specific heats

Apparatus and Experimental Methods

Wind Tunnel Description

The wind tunnel test was conducted in the Langley Unitary Plan Wind Tunnel, which is a continuous flow, variable pressure, supersonic wind tunnel. The tunnel contains two test sections that

are approximately 4 ft by 4 ft square and 7 ft long. Each test section covers only part of the

Mach number range of the tunnel. The nozzle ahead of each test section consists of an asymmetric

sliding block that allows continuous Mach number variation during tunnel operations from 1.5 to

2.9 in the low Mach number test section (#1) and 2.3 to 4.6 in the high Mach number test section

(#2). Reference 13 contains a complete description of the facility along with test section calibration

information.

2
Table 1 shows the nominal free-stream conditions used during this investigation in test section #1. Test section #2 was not used for this test.

Table 1. Nominal free-stream test conditions

M Re, ft−1 p0, psfa T0,

◦F q, psfa p, psfa

2.00 2.00 1253 125 448.5 160.2

The tunnel air dew point was maintained below −20◦F (at atmospheric pressure) to minimize

water vapor condensation effects.

General Test Description

Conical Survey Probe

Figure 1 shows a photograph and sketch of the wind tunnel test setup for the slender conical survey

probe. One of the test section doors that normally contains schlieren windows was replaced with a

solid steel door so that some of the sonic boom measurement hardware (free-stream reference probe,

survey probe, and transducer box) could be attached to the tunnel sidewall. The reference probe,

which was also a slender conical probe, was mounted to the tunnel sidewall above and slightly

upstream of the survey probe using a fixed (nonmovable) support bracket. The conical survey

probe was mounted to the sidewall near the tunnel centerline using a support that was part of a

mechanism that could move the probe longitudinally in the test section. However, during this test

the conical survey probe remained at a fixed longitudinal position for all runs where it was used.

A transducer box was located above and downstream of the conical survey probe location and was

used to house pressure transducers that measured the differential pressure between the reference

and survey probes, and a transducer that measured just the reference probe pressure. Figure 2

shows the relative positions of the sonic boom hardware. Figure 3 shows the overall dimensions

of the reference probe mounting bracket, survey probe mechanism, and transducer box. Details of

the reference and survey probes are presented in the Instrumentation and Measurements section.

Wedge Survey Probe

Figure 4 shows a photograph and sketch of the wind tunnel test setup for the wedge survey probe.

The test layout for the wedge survey probe was exactly the same as the conical survey probe except

that the conical survey probe and mechanism were replaced by the wedge probe and a wedge probe

holder. The leading edge of the wedge survey probe at the probe centerline was located at the same

position in the tunnel as the pressure orifices in the conical survey probe. The reference probe

remained on the tunnel sidewall, and the measured reference probe pressure was used in the wedge

survey probe data reduction similar to the conical survey probe data reduction (see Corrections

section). Figure 5 shows the overall dimensions of the wedge probe holder. Details of the wedge

survey probe are presented in the Instrumentation and Measurements section.

Aircraft Model

The aircraft model used during this test was a generic business jet configuration that had previously

been tested in UPWT and was designated as the straight-line segmented leading edge (SLSLE)

model. A sketch and photograph of the model are shown in figure 6. The SLSLE model was chosen

3
for this test because it was available and because data from the previous test were accessible for

comparison (ref. 8). The SLSLE model was tested without boundary layer transition grit. The

SLSLE configuration was designed using the following criteria:

• Cruise Mach number . . . . . . . . . . . . . . . . . . . . . . 2.00

• Beginning cruise weight . . . . . . . . . . . . . 88,000 lbf

• Beginning cruise altitude . . . . . . . . . . . . . 53,000 ft

• Sonic boom ground overpressure . . . . . . . 0.5 psfd

Additional details about the overall design of the model can be found in references 8 and 14.

Model Installation

The SLSLE model and sting were pinned together and were designed not to be taken apart. The

sting was attached to the sonic boom angle of attack (AOA) mechanism, which was in turn attached

to the tunnel roll coupling and model support system (see fig. 1a). The SLSLE model was tested

with positive normal force in the horizontal plane, i.e., wings vertical, for all of the sonic boom

pressure signature runs.

The tunnel angle of attack mechanism was not used to set the model angle of attack and

remained at a fixed position during this test. Instead, the sonic boom AOA mechanism was

used to set the model angle of attack to approximately 2.3

◦

. The AOA consisted of both the

pitch angle set with the sonic boom AOA mechanism and deflection caused by aerodynamic loads.

During this test, the sonic boom AOA mechanism pitch angle was set to approximately 1.7

◦

to

match one of the settings used during the previous test of the SLSLE model in UPWT. Because

data from a previous test that used the sonic boom AOA mechanism showed that the mechanism

contained approximately 0.2

◦ of play (movement of the pitch mechanism that was not indicated

by a linear potentiometer located inside the mechanism), a jam nut was fabricated and installed in

the mechanism to lock it at the required pitch angle. Figure 7 shows the jam nut installed in the

sonic boom AOA mechanism.

The tunnel model support system was used to position the SLSLE model laterally and longitudinally in the test section relative to the conical probe or the wedge probe. During this test,

the model nose was positioned at h ≈ 13.5 in. (see fig. 2b and 4c) then the tunnel model support

system was disabled in the lateral direction to prevent h from varying during the test. The tunnel

model support system longitudinal movement capability was used to move the SLSLE model past

either the conical probe or wedge probe to measure the sonic boom pressure signature. During

each pressure signature run, the model was moved longitudinally approximately 16.5 in.

During a typical run, the SLSLE model was initially positioned so that the nose shock was

located downstream of the conical survey probe or wedge probe. The model was moved forward

in 0.125 in. increments while the model sonic boom pressure signature data were acquired. Wedge

probe data were also acquired in continuous sweep runs where the model was moved continuously

past the probe. During the continuous sweep runs, the model was again positioned so that the nose

shock was located downstream of the wedge probe. The data acquisition system was started, and

approximately 10 s of data were acquired before the model movement began. After the model was

moved forward the required distance, the model movement was stopped, and data were acquired

for an additional 10 s.

4
Instrumentation and Measurements

Sketches of the conical reference and survey probes are shown in figure 8. The probes were identical

4

◦

included angle cones with a hole drilled through the probe and into a central chamber creating

two static pressure orifices. For these tests, the free-stream reference probe orifices were oriented

such that one orifice was on top of the probe and the other on the bottom of the probe when viewing

the probe from the side, i.e., looking into the tunnel sidewall. The conical survey probe orifices

should have been oriented the same as the reference probe; however, because of an installation

mistake, they were oriented such that one orifice was facing the tunnel sidewall used to mount

the probes and the other was facing toward the model. Comparison of the sonic boom pressure

signatures from the current test to a signature obtained during the previous test of the same model

in UPWT shows no significant differences indicating that the misalignment of the conical survey

probe orifices did not adversely affect the pressure signature. The comparison will be presented

later in this report. The lengths of stainless steel tubing used to connect the reference and survey

probes to the pressure transducers located in the transducer box are noted in figure 8. The final

pressure connections inside the transducer box used flexible tubing (7/32 in. outside diameter, OD,

by 3/32 in. inside diameter, ID).

Figure 9 shows a schematic of the reference and conical survey probe connections to the pressure

transducers. A solenoid activated valve that could be remotely operated was used to equalize

the pressures across the differential pressure transducer to minimize the risk of over pressurizing

the transducer during tunnel start and stops. The differential pressure between the reference

and conical survey probe was measured with a ±13.006 psfd (±2.5 in. water column) pressure

transducer, which had a quoted accuracy of ±0.018 psfd in the manufacturer’s product literature.

An in-situ calibration of the differential pressure transducer was performed, and the uncertainty

in the difference between the applied and measured pressures, otherwise know as the regression

uncertainty, was ±0.016 psfd at a 95 % confidence level. In addition, the reference probe pressure

was measured directly with a 720 psfa absolute pressure transducer, which had a manufacturer’s

quoted accuracy of ±0.72 psfa. An in-situ calibration of the absolute pressure transducer was

performed, and the regression uncertainty was ±0.172 psfa at a 95 % confidence level.

The transducer box was located on the tunnel sidewall above and downstream of the reference

and conical survey probes. The purpose of the transducer box was to house the differential and

absolute pressure transducers as close to the reference and conical survey probes as possible to

minimize pressure lag effects. The transducer box was sealed, and the inside was maintained at

near atmospheric conditions so that there would be no significant temperature or pressure effects on

the pressure transducers. The solenoid activated valve was also located inside the transducer box.

Figure 10 shows the inside of the transducer box with the two pressure transducers and solenoid

valve.

The transducer box was fabricated out of aluminum with a polycarbonate insulating cover,

which can be seen in figure 1a. The aluminum box was water cooled using 0.125 in. OD copper

tubing epoxied into grooves machined into the sides, top, and bottom of the box. There were four

separate cooling circuits for the left side, right side, top, and bottom of the transducer box. Cooling

water was supplied to each circuit, and the water flow was controlled with a small brass needle valve.

In addition to the water cooling, atmospheric air was circulated inside the box to help maintain a

constant temperature inside the box. Two 0.5 in. OD nylon tubes were routed to the box and were

used to supply cooling air to the box using a vacuum cleaner to pull atmospheric air through one

of the nylon tubes, into the box, and then out the second nylon tube. Six type T (copper/coppernickel) thermocouples were installed inside the transducer box to monitor the differential pressure

transducer, air, and transducer box wall temperatures.

5
Sketches and photographs of the wedge probe are shown in figure 11. The wedge probe had a

half angle of 8◦. The upper surface of the wedge probe had a total pressure tube and two static

pressure orifices (teed together) in the wedge surface. The lower wedge surface had a single total

pressure tube. Three pressure transducers were located inside the cylindrical portion of the wedge

probe. The total pressure tubes were measured with individual 10 psia transducers, and the static

pressure orifices were measured with a 5 psia transducer. The manufacturer’s quoted accuracies of

the 10 psia and 5 psia transducers were ±0.05 psia and ±0.025 psia, respectively.

A type T thermocouple was attached to the aft end of the cylindrical portion of the wedge

probe near the electrical connector as shown in figure 12. For this photograph, the cover plate on

the wedge probe holder was removed, and the wedge probe was positioned further downstream in

the holder than the normal wind on position. The purpose of this thermocouple was to measure

the approximate temperature of the pressure transducers during the wind-on runs. The pressure

transducers were supposed to be temperature compensated; however, previous calibrations of the

transducers at NASA Dryden Flight Research Center showed that some of the transducers were

not well temperature compensated (ref. 11). Therefore, the pressure transducers were recalibrated

after the present test at the approximate mean temperature measured by the thermocouple during

all wedge probe runs (95◦F). All of the wedge probe data were re-reduced after the test using the

new pressure transducer calibration constants.

Normal force and pitching moment data on the SLSLE model were measured with a 2-component

electrical strain gage balance that was integral to the sting. The strain gages were located near the

aft end of the sting and were covered with auto body filler that was faired to the sting contour.

Figure 13 shows the locations of the model and balance moment reference centers. The full scale

balance limits are shown in table 2 along with the computed balance accuracies as a percentage of

full scale balance limits. To compute the balance accuracies, the balance calibration data were run

through the balance calibration equations. The standard deviation of the difference between the

computed and applied loads was determined for all of the calibration loads. The balance accuracies

reported in table 2 are at a 95 % confidence level.

Table 2. Range and accuracy of balance components

Component Range Accuracy

Normal force ±5 lbf ±0.23 % of full scale

Pitching moment ±109.2 in·lbf ±0.04 % of full scale

Two platinum resistance thermometers (PRT) were installed on the sting; one near the forward

balance bridge and the second near the aft balance bridge. The purpose of the PRTs was to monitor

the temperature gradient across the balance bridges and not to compensate for balance sensitivity

changes caused by temperature. Data were only acquired after the two PRT temperatures stabilized

with minimal temperature differential.

The tunnel stagnation pressure was measured with a 100 psia bourdon tube pressure transducer

that had a manufacturer’s quoted accuracy of ±0.003 psia at a 95 % confidence level. The tunnel

stagnation temperature was measured with a platinum resistance thermometer.

The model support system lateral and longitudinal movement were measured by absolute rotary

encoders that were mounted to the system drive screws. The estimated accuracy of the model

support system position based on calibration data was ±0.005 in. for both the longitudinal and

lateral positions.

6
The model support system AOA was measured with an accelerometer mounted to the support

system just downstream of the roll coupling and was adjusted so that the sonic boom AOA mechanism was level before the SLSLE model was rolled to the wings vertical position. The model

support AOA mechanism was not adjusted after leveling the sonic boom AOA mechanism.

The sonic boom AOA mechanism pitch angle was measured with a linear potentiometer. As

discussed earlier, a jam nut was used to lock the mechanism to a single pitch angle. However,

the jam nut could have locked in some unknown pitch error caused by the sonic boom AOA

mechanism play. Based on unpublished checks conducted during a previous test, the mechanism

play (and, consequently, the unknown pitch error) was as large as 0.2

◦

. Because the sonic boom

AOA reading probably contained some fixed unknown error, the computed SLSLE model nose

separation distance, h, which was a function of the pitch angle, also probably contained some error.

However, since the pitch angle was fixed for the entire test, the small error in h would be constant

for the entire test and, therefore, would not affect the results or conclusions of the test.

Data were acquired in either a move-pause or continuous mode depending on the run. The data

acquisition system scan rate for the move-pause runs was 30 frames/s for two seconds; all of the

instrumentation readings (millivolt values) acquired during the two second period were averaged

before data reduction. The data acquisition system scan rate for the continuous runs was 120

frames/s. The data acquisition system used a 1 Hz low pass filter (2-pole Butterworth).

Wedge Probe Data Reduction

Using the two stagnation pressure measurements and the upper surface static pressure measurement

on the wedge probe, an iterative procedure as described by Bobbitt (ref. 10 and 11) can determine

the static pressure ahead of the wedge probe. The step by step procedure used for the wedge probe

data obtained during this test is documented in the appendix. The computed static pressure ahead

of the wedge probe is then used to compute the sonic boom pressure signature parameter.

Corrections

The data acquired during the test were not corrected for tunnel flow angularity. The distance

from the model nose to the conical survey probe or wedge probe measured perpendicular to tunnel

sidewall, h, was corrected for sting deflection caused by aerodynamic loads. In addition, the model

AOA was corrected for sting deflection caused by aerodynamic loads. Because the sonic boom AOA

mechanism was locked at one position, the SLSLE model AOA remained at approximately 2.3

◦

for

the entire test.

The measured sonic boom pressure signature parameter was defined as (∆p/pref )unc. For the

conical survey probe, ∆p was the measured differential pressure between the conical survey probe

and the reference probe. For the wedge survey probe, ∆p was the difference between the computed

static pressure ahead of the wedge probe and the reference probe pressure (p1 − pref ).

Because of static pressure variation within the tunnel test section, the ∆p values for the conical

and wedge survey probes were not equal to zero. Consequently, the uncorrected sonic boom pressure

signature parameter, (∆p/pref )unc, was also not equal to zero when the model nose shock was

located downstream of either the conical survey probe or wedge survey probe, i.e., the probes

were located in the free-stream flow. Therefore, the sonic boom pressure signatures were adjusted

by averaging all (∆p/pref )unc values with ∆x ≤ 21.25 in. during a signature run (conical and

wedge survey probes located in the free-stream flow) and subtracting the average value from each

7
(∆p/pref )unc value, i.e.,



∆p

pref 

cor

=



∆p

pref 

unc

−



∆p

pref 

avg

(1)

Figure 14 shows typical corrected and uncorrected sonic boom pressure signatures as a function

of ∆x for the conical and wedge survey probes to illustrate the approximate magnitude of the

correction. No additional corrections or adjustments were performed to the sonic boom pressure

signature data.

Results and Discussion

All of the plots in this section will show the corrected sonic boom pressure signature parameter

(∆p/pref )cor as a function of ∆x. As mentioned previously, the sonic boom angle of attack mechanism was locked at one position to eliminate inadvertent angle of attack changes caused by the

play in the mechanism. The resultant angle of attack of the SLSLE model was approximately 2.3

◦

for the entire test.

Conical Survey Probe Data Comparison Between Tests

Figure 15 shows a comparison between the sonic boom pressure signature data as a function ∆x

for two sets of three back-to-back repeat runs obtained during the current test and data acquired

during the previous test of this model in UPWT as described in reference 8. The two sets of backto-back repeat runs were obtained on two different days. The results show reasonable agreement

between the six repeat runs of the current test. Comparison with the previous test data shows a

slight (≈ 0.5 in.) positive shift in ∆x for the previous data. However, the magnitude and location of

the signature peaks compare well between the tests indicating that nothing significant had changed

between the tests, which gave confidence that the current test setup was satisfactory. The cause of

the ∆x shift between the two tests is unknown.

One significant difference between the tests is apparent near ∆x = 33 in. The previous test data

show a negative peak as the flow expands aft of the model wing whereas the data for the current test

flattens and does not peak. For the current test, the differential pressure transducer that measured

∆p was over scaled in this region, and an internal mechanical stop inside the transducer prevented

over pressurization of the transducer. Although most details of the previous and current test were

identical, the reference and survey probes for the previous test were 2◦included angle cones while

the current test used probes with 4◦included angles. The larger angles on the reference and survey

probes resulted in a larger measured ∆p that caused the differential pressure transducer diaphragm

to hit the mechanical stop resulting in a constant millivolt output from the transducer. Because

the purpose of this test was to compare the conical survey probe data with the wedge survey probe

data, the over pressurization of the differential pressure transducer in this region did not affect the

conclusions of this test.

Data Comparison Between Conical and Wedge Survey Probes

Figure 16 shows comparisons between the sonic boom pressure signatures obtained with the conical

probe and the wedge probe. Two sets of three back-to-back runs were obtained on two different

days for both the conical probe and the wedge probe. Each set of repeat runs are shown in figure 16.

The results show that the wedge probe signatures are offset in the +∆x direction relative to the

8
conical probe data and that the magnitude of the signature peaks were generally larger than the

conical probe data.

At the beginning of the pressure signatures, the sonic boom pressure signature parameter is zero

for both the conical probe and wedge probe because the model nose shock is downstream of both the

conical and wedge probes. At ∆x . 22 in., the wedge probe pressure signature shows a significant

decrease while the conical probe signature is still zero. The reason for the sharp decrease in the

wedge probe signature is illustrated in figure 17. At the beginning of the wedge probe pressure

signature, the model nose shock is downstream of the wedge probe and, consequently, the wedge

probe is located in the free-stream flow. As the pressure signature run progresses, the nose shock

will eventually pass over the wedge upper surface stagnation pressure tube (p03), but the upper

wedge surface static pressures (p2) and lower surface stagnation pressure tube (p04) will be upstream

of the model nose shock. Because the equations used to calculate the wedge probe parameters were

derived assuming the entire probe is in a uniform flow field, the spatial separation of the pressure

measurements on the wedge probe results in an incorrect calculation of the static pressure ahead

of the wedge probe, p1. Because the wedge probe is never located in a uniform flow field along the

entire sonic boom pressure signature (except at the beginning of the signature), the entire wedge

probe signature is affected by the pressure measurement spatial separation issue.

To better illustrate the wedge probe pressure measurement spatial separation issue, the wedge

probe individual pressure measurements that were obtained during a continuous run were plotted.

Details of acquiring continuous sonic boom pressure signature data are given in reference 12. During

the continuous run, the SLSLE model was continuously moved in the axial direction while the

pressure signature data were obtained. Figure 18 shows a comparison between the wedge probe

move-pause pressure signatures from figure 16a compared to a single continuous pressure signature

obtained with the wedge probe. The continuous wedge probe pressure signature is similar to the

move-pause data except that the continuous data shows more unsteadiness because the continuous

data were not averaged. Figure 19 shows a comparison between the slender conical probe movepause pressure signatures from figure 16a compared to the single continuous pressure signature

obtained with the wedge probe that is shown in figure 18. Finally, figure 20 shows the continuous

data individual wedge probe pressures from figure 19 plotted as function of ∆x for values near

22 in., i.e., the ∆x location where the model nose shock first passes over the wedge probe. The

thick vertical lines on the plots for p03, p2, and p04 show approximately where the pressures begin

to rise as the nose shock passes over each of the pressure orifices or tubes. The plot of p1, which is

computed from the wedge probe equations, shows that p1 remains constant at approximately 160

psfa while the model nose shock is downstream of the wedge probe. As the nose shock passes over

the upper surface stagnation pressure tube, p03 increases and p1 begins to decrease, which causes

(∆p/pref )cor to decrease as previously shown in figure 19.

Although it is possible to reduce the size of the wedge probe and, thus, reduce the spatial

separation of the probe pressure measurements as suggested in reference 10, there will always

be spatial separation of the pressure measurements that will cause issues measuring sonic boom

pressure signatures with the wedge probe in supersonic wind tunnels.

Concluding Remarks

A wind tunnel investigation was conducted in the Langley Unitary Plan Wind Tunnel to determine

the effectiveness of a wedge probe to measure aircraft sonic boom signatures compared to slender

conical probes, which have typically been used in the past. Sonic boom signatures were measured

on an existing generic business jet model at a constant angle of attack and at a model nose to

survey probe (wedge or conical) separation distance of 13.5 in. The sonic boom signatures were

9
obtained at a Mach number of 2.0 and at a free-stream unit Reynolds number of 2 million per foot.

The results of the test showed significant differences between the sonic boom pressure signatures

measured with the wedge probe compared to the conical probe. The wedge probe data reduction

equations assumed that the probe was located in a uniform flow field, and the spatial separation of

three measured pressures on the wedge probe caused the calculation of the static pressure ahead

of the wedge probe to be in error. Because the wedge probe is never located in a uniform flow field

along the entire sonic boom pressure signature (except at the beginning of the signature), the entire

wedge probe signature is affected by pressure measurement spatial separation issue. Although it

is possible to reduce the size of the wedge probe and, thus, reduce the spatial separation of the

probe pressure measurements, there will always be spatial separation of the pressure measurements

that will cause issues measuring sonic boom pressure signatures with the wedge probe in supersonic

wind tunnels.

References

1. Carlson, Harry W.: An Investigation of Some Aspects of the Sonic Boom by Means of WindTunnel Measurements of Pressures about Several Bodies at a Mach Number of 2.01.

NASA TN D–161, 1959.

2. Carlson, Harry W.: Correlation of Sonic-Boom Theory with Wind-Tunnel and Flight Measurements. NASA TR R–213, 1964.

3. Mendoza, Joel P.; and Hicks, Raymond M.: Further Studies of the Extrapolation of Near-Field

Overpressure Data. NASA TM X–2219, 1971.

4. Hunton, Lynn W.; Hicks, Raymond M.; and Mendoza, Joel P.: Some Effects of Wing Planform

on Sonic Boom. NASA TN D–7160, 1973.

5. Carlson, H. W.; and Morris, O. A.: Wind-Tunnel Sonic-Boom Testing Techniques. AIAA

Paper 66–765, 1966.

6. Carlson, Harry W.; Mack, Robert J.; and Morris, Odell A.: A Wind-Tunnel Investigation of

the Effect of Body Shape on Sonic-Boom Pressure Distributions. NASA TN D–3106, 1965.

7. Carlson, Harry W.; and Mack, Robert J.: A Study of the Sonic-Boom Characteristics of a

Blunt Body at a Mach Number of 4.14. NASA TP–1015, 1977.

8. Mack, Robert J.; and Kuhn, Neil: Determination of Extrapolation Distance with Measured

Pressure Signatures from Two Low-Boom Models. NASA TM–2004–213264, 2004.

9. Wilcox, Floyd J., Jr.; Elmiligui, Alaa A.; Wayman, Thomas R.; Waithe, Kenrick A.; Howe,

Donald C.; and Bangert, Linda S.: Experimental Sonic Boom Measurements on a Mach 1.6

Cruise Low-Boom Configuration. NASA TM–2012–217598, 2012.

10. Bobbitt, Percy J.; and Darden, Christine M.: A Wedge Shaped Supersonic Flow Field Probe.

NASA CP–10133, pp. 379–398, 1994.

11. Bobbitt, Percy J.; Maglieri, Domenic J.; Banks, Daniel W.; and Fuchs, Aaron W.: Wedge

and Conical Probes for the Instantaneous Measurement of Free-Stream Flow Quantities at

Supersonic Speeds. AIAA Paper 2011–3501, 2011.

12. Wilcox, Floyd J., Jr. and; Elmiligui, Alaa A.: Experimental Measurements of Sonic Boom

Signatures Using a Continuous Data Acquisition Technique. NASA TP–2013–218035, 2013.

10
13. Jackson, Charlie M., Jr.; Corlett, William A.; and Monta, William J.: Description and Calibration of the Langley Unitary Plan Wind Tunnel. NASA TP–1905, 1981.

14. Mack, Robert J.; and Kuhn, Neil S.: Determination of Extrapolation Distance With Pressure

Signatures Measured at Two to Twenty Span Lengths From Two Low-Boom Models. NASA

TM–2006–214524, 2006.

11
Solid steel door blank

Reference probe

Transducer box

Conical survey probe

Survey probe mechanism

SLSLE model and sting

Roll coupling

Sonic boom AOAmechanism

Instrumentation leads,cooling air, and coolingwater

2012–L–03809

Flow

Model support systemAOA mechanism

Model support system (a) Model mounted in wind tunnel. Figure 1. General experimental test setup for the conical survey probe.

12
Tunnel door

Roll coupling

Solid steel door blank

Model support system

(can move both laterally and longitudinally) Lateral

SLSLEmodel and sting Sonic boom

AOA mechansim Model support

system AOAmechansim

Referenceprobe

Flow

Longitudinal

Conical survey probe

Survey probe mechanism

(b) Top view (transducer box removed for clarity).

Figure 1. Concluded.

13
Reference probe

Transducerbox

16.06 22.63

36.97

42.01

Center 

of two

orifices

Center 

of two

orifices

Conical survey probe

Survey probemechansim

28.25

Solid steel door blank

Test section doorleading edge Tunnel floor

51.19

Flow

Pressuretubing

Pressuretubing

(a) Side view.

Figure 2. Details of the experimental setup for the conical survey probe. All dimensions are in inches.

14
10.50

∆x

h42.00

Conical survey probeConical survey probe orifices

Referenceprobe

SLSLEmodel and sting

Solid steel door blank

Sonic boomAOA mechanism

10.00

Test section doorleading edge

Sonic boom

AOA mechanism

pivot

Flow

(b) Top view (transducer box removed for clarity).

Figure 2. Concluded.

15
10.00

0.50

5.00

0.75

17.06°

10.31

5.00

1.00 0.75

A

A

Section A-A

Referenceprobe

(a) Reference probe holder.

Figure 3. Various hardware sketches. All dimensions are in inches unless otherwise noted.

16
10.50

4.00

30.35

19.50

2.00

7.06

0.75

3.92

5.00

3.92

0.59

A

A

B

B

1.00

21.80°

17.06°

17.06°

Section A-A

Section B-B

Conical survey probe

(b) Survey probe mechanism.

Figure 3. Continued.

17
Fitting for 0.125 dia. pressure tubing

3.25

7.505.25

2.50

8.58

8.71

21.01

53.1°

(c) Transducer box.

Figure 3. Concluded.

18
Solid steel door blank

Reference probe

Transducer box

Wedge survey probe

SLSLE model and sting

Roll coupling

Sonic boom AOAmechanism

Instrumentation leads,cooling air, and coolingwater

2012–L–03803

Flow

Model support systemAOA mechanism (a) Model mounted in wind tunnel. Figure 4. General experimental test setup for the wedge survey probe.

19
Reference probe

Transducerbox

16.06

36.97

Center 

of two

orifices

28.25

Solid steel door blank

Test section doorleading edge Tunnel floor

51.19

Flow

Pressuretubing

22.63

42.01

wedge probe

leading edge

Wedge survey probe

(b) Side view.

Figure 4. Continued.

20
10.50

∆x

h42.00

Wedge survey probeWedge probe leading edge

Referenceprobe

SLSLEmodel and sting

Solid steel door blank

Sonic boomAOA mechanism

10.00

Test section doorleading edge

Sonic boom

AOA mechanism

pivot

Flow

(c) Top view (transducer box removed for clarity).

Figure 4. Concluded.

21
7.94

3.90

0.750

1.000

11.25

Cover

plate

0.750 dia.

0.50

1.44

2.341

6.691

Figure 5. Wedge probe holder. Dimensions are in inches.

22
0.568

7.590

4.500

56.516°

8.992

(a) Overall dimensions.

Figure 6. Straight-line segmented leading edge model description. All dimensions are in inches unless otherwise noted.

23
L–2003–01611

(b) Top view.

L–2003–01612

(c) Side view.

Figure 6. Concluded.

24
Jam nut

Figure 7. Jam nut used to lock the position of the sonic boom AOA mechanism.

25
0.035 dia. thru

0.050 dia.

To pressure transducers

4°

1.500

3.580

5.000

0.250

Tubing,

0.125 dia. OD

0.070 dia. ID

Tubing,0.094 dia. OD0.063 dia. ID

Tubing,0.125 dia. OD0.070 dia. ID

0.375 dia.0.188 dia.

9.925

0.075

A A

Section A-A

(sectioning excludes tubing) Tubing lengths (approximate)

Probe 0.094 dia. OD 0.0125 dia. OD

ReferenceSurvey

15

3

7

19

Figure 8. Conical reference and survey probe drawing. All dimensions are in inches unless otherwise noted.

26
± 13.006 psfd

pressuretransducer

Dashed line indicatestransducer box locatedinside of the tunnel

5 psiapressuretransducer

Reference probe

Solenoid operated bypass valve(used to equalize pressure across differential pressuretransducer during tunnel starting/stopping)

Survey probe

Figure 9. Conical reference and survey probe pressure hookup.

27
5 psia pressure

transducer

± 0.09 psid differentialpressure transducer

Instrumentation leadsand cooling air

Cooling water

Solenoid bypass valve

2012–L–03808

Figure 10. Transducer box (insulating plastic cover removed).

28
8.82

3.82

0.75

1.00

Three Kulite transducershoused in cylinderical body2 - 10 psia pressure transducers1 - 5 psia pressure transducer

16° wedge angle

Electricalconnector

(a) Overall dimensions.

Figure 11. Wedge probe details. All dimensions in inches unless otherwise noted.

29
1.00

0.50

0.12

0.15

0.06

0.50

0.100.05

0.88

Two staticpressure orifices (0.01 dia)

0.15

0.23

0.10

0.29

0.02 OD x 0.01 ID tubing

0.12

8.0°± 0.1°8.0°± 0.1°

Two staticpressure orifices (0.01 dia)

0.02 OD x 0.01 ID tubing

(b) Wedge details.

Figure 11. Continued.

30
Upper surface stagnation

pressure probe

Lower surface stagnationpressure probe Static pressure orifices

2012–L–00078

(c) Upper surface.

Lower surface stagnationpressure probe

2012–L–00079

(d) Lower surface.

Figure 11. Concluded.

31
Thermocouple

Electrical connection fortransducer wiring

Downstream face of wedgeprobe holder with cover plateremoved

Figure 12. Thermocouple attached to aft end of wedge probe.

32
+PM

+NF

6.740

28.535

Model

moment

reference

center

reference area = 10.08 in2 = 0.07 ft2

reference length = 1.0 in.

Balance

moment

reference

center

Aft balancebridge location

Forward balancebridge location

4.50

8.992

Figure 13. Moment reference center locations. All dimensions are in inches.

33
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Δx, in.

-.01 -.02 -.03 -.04 -.05 -.06 -.07 -.08 

0 

.02 .01 

p/p Δ( ref)cor p/p Δ and ( ref)unc

uncorrected corrected 

run 

47 47 

M 

2.00 2.00 

Re, 1/ft 

2.00 2.00 

h, in.

13.60 13.60 

(a) Conical survey probe.

Figure 14. Comparison of uncorrected and corrected sonic boom pressure signatures.

34
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Δx, in.

-.01 -.02 -.03 -.04 -.05 -.06 -.07 -.08 -.09 -.10 

0 

.02 .01 

p/p Δ( ref)cor p/p Δ and ( ref)unc

uncorrected corrected 

run 

91 91 

M 

2.00 2.00 

Re, 1/ft 

2.00 2.00 

h, in.

13.63 13.63 

(b) Wedge survey probe.

Figure 14. Concluded.

35
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 

Δx, in.

-.005 -.010 -.015 -.020 -.025 

0 

.020 .015 .010 .005 

p/pΔ( ref)cor 

test 

1998 1998 1998 1998 1998 1998 1906 

run 

47 48 49 71 72 73 

8 

M 

2.00 2.00 2.00 2.00 2.00 2.00 2.00 

Re, 1/ft 

2.00 2.00 2.00 2.00 2.00 2.00 2.00 

h, in.

13.60 13.58 13.59 13.63 13.63 13.63 13.50 

probe 

4 ̊ cone 4 ̊ cone 4 ̊ cone 4 ̊ cone 4 ̊ cone 4 ̊ cone 2 ̊ cone 

current test current test current test current test current test current test previous test 

Figure 15. Sonic boom pressure signature comparison between tests.

36
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Δx, in.

-.005 -.010 -.015 -.020 -.025 -.030 -.035 

0 

.020 .015 .010 .005 

p/p Δ( ref)cor 

run 

47 48 49 91 92 93 

M 

2.00 2.00 2.00 2.00 2.00 2.00 

Re, 1/ft 

2.00 2.00 2.00 2.00 2.00 2.00 

h, in.

13.60 13.58 13.59 13.63 13.63 13.63 

configuration 

conical probe conical probe conical probe wedge probe wedge probe wedge probe 

(a) First set of repeats.

Figure 16. Comparison of sonic boom pressure signatures obtained with conical and wedge probes.

37
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Δx, in.

-.005 -.010 -.015 -.020 -.025 -.030 -.035 

0 

.020 .015 .010 .005 

p/p Δ( ref)cor 

run 

71 72 73 

111 112 113 

M 

2.00 2.00 2.00 2.00 2.00 2.00 

Re, 1/ft 

2.00 2.00 2.00 2.00 2.00 2.00 

h, in.

13.63 13.63 13.63 13.64 13.63 13.64 

configuration 

conical probe conical probe conical probe wedge probe wedge probe wedge probe 

(b) Second set of repeats.

Figure 16. Concluded.

38
M = 2.0

Model noseshock

Modelmovement

SLSLE model and sting

Oblique shock

Bow shock

bow shock

Oblique shock

p03 (measured)

p04(measured)

p2 (measured)

p1 (computed)

Figure 17. Sketch illustrating interaction of model nose shock and wedge probe.

39
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 

Δx, in.

-.005 -.010 -.015 -.020 -.025 -.030 -.035 

0 

.025 .020 .015 .010 .005 

p/pΔ( ref)cor 

run 

91 92 93 94 

M 

2.00 2.00 2.00 2.00 

Re, 1/ft 

2.00 2.00 2.00 2.00 

h, in.

13.63 13.63 13.63 13.62 

configuration 

wedge probe wedge probe wedge probe wedge probe 

v, in/s 

0.0 0.0 0.0 

0.088 

move-pause move-pause move-pause continuous 

Figure 18. Comparison of wedge probe move-pause and continuous pressure signatures.

40
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 

Δx, in.

-.005 -.010 -.015 -.020 -.025 -.030 

0 

.025 .020 .015 .010 .005 

p/pΔ( ref)cor 

run 

47 48 49 94 

M 

2.00 2.00 2.00 2.00 

Re, 1/ft 

2.00 2.00 2.00 2.00 

h, in.

13.60 13.58 13.59 13.62 

configuration 

conical probe conical probe conical probe 

wedge probe 

v, in/s 

0.0 0.0 0.0 

0.088 

move-pause move-pause move-pause continuous 

Figure 19. Comparison of conical probe move-pause pressure signatures and wedge probe continuous pressure signature.

41
M = 2.0

Model noseshock

SLSLE model and sting

Oblique shock

Bow shock

Bow shock

Oblique shock

p03

p04

p2 p1 (computed)

21.0 21.2 21.4 21.6 21.8 22.0 22.2 22.4 22.6 22.8 23.0 23.2 23.4 

∆x, in.

1065 1060 1055 1050 

, psfa 03p

run 

94 

M 

2.00 

Re, 1/ft 

2.00 

h, in.

13.62 

configuration 

wedge probe 

v, in/s 

0.088 continuous 

265 260 255 250 

, psfa 2p

905 900 895 

, psfa 04p

164 162 160 158 

, psfa 1p

Note: The thick vertical lines on the plots for p03, p2, and p04

show approximately where the pressures begin to rise as the nose shock passes over each of the pressure orifices or tubes.

Figure 20. Wedge probe individual pressures measured during a continuous sweep run.

42
Appendix

Wedge Probe Data Reduction Procedure

The procedure used to reduce the data from the wedge probe is presented in this appendix.

The procedure is based on the method documented in references 10 and 11. Figure A1 shows a

sketch of the wedge and the nomenclature used in the equations. The pressures p03, p04, and p2

were measured. These pressures and the known half angle of the wedge were used in an iterative

procedure to compute the remaining variables listed in figure A1. The equations were derived for

air with γ = 1.4.

Flow

p1

M1

p01

p2

M2

p02

p03 measurement

p04 measurement

θf

θ

δ w

Static pressure orifice

for p2 measurement

Oblique shock

Bow shock

Bow shock

Oblique shock

Figure A1. Sketch of wedge probe with nomenclature identified.

The following variables are measured or known:

p2 measured static pressure on wedge upper surface, psfa

p03 measured stagnation pressure behind normal shock on wedge upper surface, psfa

p04 measured stagnation pressure ahead of wedge oblique shock and behind normal

shock, psfa

w wedge half angle (8◦for wedge probe)

Using the above measured or known values in the procedure below results in the following

computed values:

M1 Mach number ahead of wedge probe

M2 Mach number behind the wedge upper surface oblique shock

p01 stagnation pressure ahead of wedge probe, psfa

p02 stagnation pressure on wedge upper surface, psfa

p1 static pressure ahead of wedge probe, psfa

δ wedge upper surface flow deflection angle, deg

θ wedge upper surface oblique shock wave angle relative to oncoming flow, deg

θf flow inclination ahead of wedge probe (θf positive as shown in figure A1), deg

43
1. Compute estimate of M2.

M2 =

s

p03

p2

 35

365/2 

5

6



2. Compute p03/p2 using estimate of M2.

p03

p2

=

(6)6M7

2

(5)7/2(7M2

2 − 1)5/2

3. Compute error between measured and calculated p03/p2.

error1 =



p03

p2



measured

−



p03

p2





calculated

p03

p2



measured

4. Determine if the absolute value of error1 is greater than 0.0001.

|error1| > 0.0001

If yes, then continue with step 5. If no, then continue with step 6.

5. Compute new estimate of M2.

M2 = M2(1 + error1)

Continue with step 2.

6. Compute p02.

p02 = p2



M2

2 + 5

5

7/2

7. Compute estimate of M1.

M1 = 72 −

p

5161.538 − 153.846M2

8. Compute estimate of ξ = p2/p1.

ξ = 1.41625 − 0.04M1 + 0.055M2

1

9. Compute Mach number ahead of wedge probe, M1, squared.

M2

1 =

5ξ(ξ + 6)

(6ξ + 1) 

p02

p2

2/7

− 5

44
10. Compute p2/p04.

p2

p04

=

5ξ

6M2

1



35M2

1 − 5

36M2

1

5/2

11. Compute error between measured and calculated p2/p04.

error2 =



p2

p04 

measured

−



p2

p04 



calculated

p2

p04 

measured

12. Determine if the absolute value of error2 is greater than 0.0001.

|error2| > 0.0001

If yes, then continue with step 13. If no, then continue with step 14.

13. Compute new estimate of ξ.

ξ = ξ(1 + error2)

Continue with step 9.

14. Compute p1.

p1 =

p2

ξ

15. Compute M1.

M1 =

q

M2

1

16. Compute p01.

p01 = p1(1 + 0.2M2

1

)

7/2

17. Compute shock wave angle, θ.

θ = arcsin s

6ξ + 1

7M2

1

18. Compute flow deflection angle, δ.

δ = θ − arcsin s

ξ + 6

7ξM2

2

19. Compute flow inclination, θf .

θf = w − δ

20. Compute uncorrected sonic boom pressure signature parameter.

(∆p/pref )unc =

p1 − pref

pref

45
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704–0188

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,

gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection

of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports

(0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall

be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

Standard Form 298 (Rev. 8/98)

Prescribed by ANSI Std. Z39.18

1. REPORT DATE (DD-MM-YYYY)

01–08–2013

2. REPORT TYPE

Technical Publication

3. DATES COVERED (From – To)

4. TITLE AND SUBTITLE

Effectiveness of a Wedge Probe to Measure Sonic Boom

Signatures in a Supersonic Wind Tunnel

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

122711.03.07.07.16.80

6. AUTHOR(S)

Wilcox, Floyd J., Jr.; Elmiligui, Alaa A.

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Langley Research Center

Hampton, VA 23681–2199

8. PERFORMING ORGANIZATION

REPORT NUMBER

L-20239

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546–0001

10. SPONSOR/MONITOR’S ACRONYM(S)

NASA

11. SPONSOR/MONITOR’S REPORT

NUMBER(S)

NASA/TP–2013–218036

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Category 02

Availability: NASA CASI (443) 757-5802

13. SUPPLEMENTARY NOTES

14. ABSTRACT

A wind tunnel investigation was conducted in the Langley Unitary Plan Wind Tunnel (UPWT) to determine the

effectiveness of a wedge probe to measure sonic boom pressure signatures compared to a slender conical probe. A

generic business jet model at a constant angle of attack and at a single model to probe separation distance was

used to generate a sonic boom signature. Pressure signature data were acquired with both the wedge probe and a

slender conical probe for comparison. The test was conducted at a Mach number of 2.0 and a free-stream unit

Reynolds number of 2 million per foot. The results showed that the wedge probe was not effective in measuring

the sonic boom pressure signature of the aircraft model in the supersonic wind tunnel. Data plots and a

discussion of the results are presented. No tabulated data or flow visualization photographs are included.

15. SUBJECT TERMS

Sonic boom; Aerodynamics; Supersonic; Wind tunnel test; Continuous data acquisition

16. SECURITY CLASSIFICATION OF:

a. REPORT

U

b. ABSTRACT

U

c. THIS PAGE

U

17. LIMITATION OF

ABSTRACT

UU

18. NUMBER

OF

PAGES

50

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email: help@sti.nasa.gov)

19b. TELEPHONE NUMBER (Include area code)

(443) 757-5802