AD-R154 063 OPERATIONAL NOISE DATA FOR THE LACV-38 AIR CUSHION 1/1 VEHICLE(U) CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPRIGN IL P SCHOMER MAR 85 CERL-TR-N-85/84 UNCLASSIFIED IRO-R4105 F/G 28/1 NL

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-- U111110 _ 1112.22

IIJI2 11111.4 11

MICROCOPY RESOLUTION TEST CHART

NATIONAL BUREAU OF STANDARDS-1963-A

'I.

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0i
US Army Corps of Engineers TECHNICAL REPORT N-85/04

Construction Engineering March 1985

*AD-A 154 063

| .7,

OPERATIONAL NOISE DATA FOR THE LACV-30

AIR CUSHION VEHICLE

by

Paul D. Schomer

Operational data for the LACV-30 air cushiont

vehicle were gathered and developed into sound

exposure level vs. distance curves. These data are

available for the Army Environmental Hygiene

Agency (AEHA) to use in developing noise zone

maps for LACV-30 operations in support of the

Army Installation Compatible Use Program (ICUZ).

ICUZ defines land uses compatible with various

noise levels and establishes a policy for achieving such

Uses.

Although the Army classifies the LACV-30 as an

amphibious vehicle, an examination of its noise

- : ) characteristics and operations showed it most closely

*resembles a helicopter. Thus the methodology for

gathering rotary wing aircraft data was used. Measureg..J ments of LACV-30's passby runs over water at

- various distances and speeds were similar in concept

LA_ to flyover and flyby measurements for helicopters,

and the land maneuver measurements corresponded

most nearly to a helicopter's hover measurements. MAY2 2 S85

B :.

Approved for public release: distribution unlimited.

...-. , . .... ..........

;.. : ... '.-,- . ,'£. -.. .- , -. .. ,. .-.-. . .- . .' ...... -. - .. .... -. - .. -. , .- . - ... .... ,. '. - .- . .. -. , .,", '
rrw

The contents of this report are not to be used for advertising, publication, or

promotional purposes. Citation of trade names does not constitute an

official indorsement or approval of the use of such commercial products.

The findings of this report are not to be construed as an official Department

of the Army position, unless so designated by other authorized documents.

.

A.t

DESTROY THIS REPORT WHEN IT IS No I ONGER NEEDED

DO NOT RETURN IT TO T~ff ORIGI.\' TOR

.J
UNCLASS I FiEL

ECURITY CLASSIFICATION OF THIS PAGE (olten Dleta Knfored)

DOCUMENTATION nREPORT PAGE READ INSTRUCTIONS

BEFORE COMPLETING FORM

1 REPORT NUMHFR 2 A, C SsION 03.RaECPIENT'S CATALOG NUMBER

* CERL TR N-85/04 5 T F R IE

I. TITLE (aid Sub,,.ti YPE OF REPORT& PERIOD COVERED

OPERATIONAL NOISE DATA FOR THE LACV-30 FINAL

AIR CUSHION VEHICLE _ _-__ _

6. PERFORMING ORG. REPORT NUMBER

7. AUTHOR(s) 8. CONTRACT OR GRANT NUMBER(a)

P. Schomer iAO-A4 105 .

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK

U.S. Army Construction Engr Research Laboratory AREA & WORK UNIT NUMBERS

P.O. Box 4005

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11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE

Fort Belvoir, VA, Research and Development March

Center (STRB-E-GRD) I. NUMBER OF PAGES

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IS. SUPPLEMENTARY NOTES

Copies are obtainable from the National Technical Information Service

Springfield, VA 22161

I. KEY WORDS (Continue on reverse elde if necessmy and Identify by block number)

1ACV-30 air cushion vehicle

air cushion vehicle

Sound cxposure level

noise(sound)

!1L ABSTRACT (Ctm anrvese eftb N teeee amd Identify by block nmthbef)

Operational data tor the LACV-30 air cushion vehicle were gathered and developed .

into sound exposure level vs. distance curves. These data are available for the Army Environmental Hygiene Agency (AEHA) to use in developing noise zone maps for LACV-30

operations in support of the Army Installation Compatible Use Program (ICUZ). ICUZ

defines land use compatible with various noise levels and establishes a policy for achieving

such uses.

Although the Army classifies the LACV-30 as an amphibious vehicle, an examination --. > L

ID I 1473 EoDTonOF I MOV GS IS OBSOLETE UNCLASSIFIED ';

/ SECUPITY CLASSIFICATION OF THIS PAGE (When Dalt Efntered)

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.............................. ..........................................................................................-.............. '. , " ,'.'.%" .'1
I I MI A (Z 0,T V P9.

SECURITY CLASSIFICATION Of THIS PAGE(Wmai Date Ltemd)

4. BLOCK 20 (Continued)

* -,of its noise characteristics and operations showed it most closely resembles a helicopter.

Thus the methodology for gathering rotary wing aircraft data was used. Measurements of

* LACV-30's passby runs over water at various distances and speeds were similar in concept

to tlyover and flyby measurements for helicopters, and the land maneuver measurements ~

corresponded most nearly to a helicopter's hover measurements. u/

-zl.
FOREWORD

This study was conducted for Fort Belvoir, VA. Research and Development Center

(STRB-E-4;RD), under IAO-A4105, dated January )984.

The work was performed by the Environmencttal Division (EN) of the U.S. Army

Construction Engineering Research ULaboratory (USA-Cf, RL). Dr. R. K. Jain is Chief of'

* LJSA-CERL-EN.

COL Paul J. Theuer is Commander and Director of USA-CERL, and Dr. L. R. Shaffer

is Technical Director.

3,
CONTENTS

pap.

DD FORM 1473 2

FOR EWORD 3

LIST OF TABLES AND FIGURES 5

1 INTRODUCTION............................................ 7

Background

Mod of echniolog TEU Transfer

2 TES OPERTIONSAND DATA COLLECTION METHODS .............. 7

DATA REDUCTION AND RESULTS ............................... 8

PassbyData

4NOISE SOURCES AND POTENTIAL NOISE MITIGATION METHODS ...... 16

5 CONCLUSION............................................. 19

APPEN DIX: SEL vs. Distance Tables for Microphones 1, 2, and

3 Averaged Over Various Typos of Operations 20

DISTRIBUTION

-S p4
- ...-- ,-, ~- -r: * l ,t - l, - o -- . : T L~ 

 -. \ * -. N N .-.  '" ,- r *% i '.. ,

TABLES

Number Page

I Overwater Passby Operations 11

2 Overland Maneuvers 13

3 LACV-30 Operational Noise Level vs. Distance Data 19 I

Al Key to Appendix Tables 20

A2 SEL vs. Distance Averaged Over 1/4 nrni at Cruise Speed,

Jan 5,6, Traveling East and West 20

A3 SEL vs. Distance Averaged Over 1/2 nmi at Cruise Speed,

Jan 5, 6, Traveling East and West 20

A4 SEL vs. Distance Averaged Over 1/8 nmi at Cruise Speed,

Jan 5, 6, Traveling East and West 20 1%

AS SEL vs. Distance, Set 1, Averaged Over 1/4 nmi at Cruise Speed,

Jan 5, 6, Traveling East and West 21

A6 SEL vs. Distance, Set 2, Averaged Over 1/4 nmi at Cruise Speed,

Jan 6, Traveling East and West 21

A7 SEL vs. Distance, Set 1, at Cruise Speed, for All Distances,

Jan 5, Traveling East and West 21

A8 SEL vs. Distance, Set 2, at Cruise Speed, for All Distances,

Jan 6, Traveling East and West 21

A9 SEL vs. Distance, Cruise Speed, Traveling East, for All Distances,

Jan 5, 6 22

A1O SEL vs. Distance, Cruise Speed, Traveling West, for All Distances,

Jan 5, 6 22 I.

Al I SEL vs. Distance, Cruise Speed, Jan 5, 6, Traveling East and West,

for All Distances 22

A l 2 SEL vs. Distance for 1/8 and 1/4 nmi at Cruise Speed,

Traveling East and West, Jan 5,6 22

A1 3 SEL vs. Distance, Set 1, 1/4 nmi at High Speed, Traveling East

and West, Jan 5 23

A14 SEL vs. Distance, Set 2, 1/4 nmi at High Speed, Traveling East

and West, Jan 6 23

AI5 SEL vs. Distance, Over 1/4 nmi at High Speed, Traveling East and West,

Jan 5, 6 23

- ................ .... ......... ,
Tables (Cont'd)

Number Page

A b SEL vs. Distance, Set 1, 1/4 nmi at Below Hump Speed, Traveling

East and West, Jan 5 23 -.

A17 SEL vs. Distance, Set 2, 1/4 nmi at Below Hump Speed, Traveling

East and West, Jan 6 24

Al 8 SEL vs. Distance, 1/4 nmi at Below Hump Speed, Traveling East

and West, Jan 5,6 24

FIGURES

Number Page

I General site layout for LACV-30 noise measurements. 9

2 Passby paths and microphone locations. 10

3 Test site layout for land maneuver measurements of the LACV-30. 12

4 Land maneuver patterns for the LACV-30. 13

5 Measurement equipment at a site. 14

6 SEL vs. distance for cruise speed. 15

7 SEL vs. distance, for cruise, high, and below hump speeds. 17

8 The l/3-octave spectra of a maneuvering craft at a distance of 275 m. 18

I

3.4

. .. I
OPERATIONAL NOISE DATA Previous USA-CERL research has addressed, to

FOR THE LACV-30 some degree, these sets of data for rotary-wing aircraft

AIR CUSHION VEHICLE and for blast noise prediction, but no previous work

addressed the noise emissions of the LACV-30 air

cushion vehicle, a significant source of noise at some

installations.4 (USA-CERL was asked by Fort Belvoir, INTRODUCTION VA, Research and Development Center to measure the

noise emissions of the LACV-30 in accordance with

Background AR 200-1.)

In recent years, residential development has occurred Objective

near military installations areas subject to high noise The objective of this study was to develop sound

levels. To ensure that this development does not affect exposure level (SEL) vs. distance curves for the LACVthe operating capabilities of those installations, the 30 for use in developing noise zone maps. As a side j U.S. Army has instituted the Installation Compatible benefit to this study, some potential reasons for the

Use Zone Program (ICUZ).' Like the Departmrent of vehicle's high noise emissions were also determined, Defcnse's (DOD) Constnction Criteria Manual and Air and they are presented with suggestions for mitigation.

Installation Compatible Use Zone program (AICUZ), .

the IC('Z program defines land uses compatible with Approach

various noise levels attd establishes a policy for achieving Since the LACV-30 is a unique vehicle in the Army,

such uses.) The ICUZ program stresses Army-unique the first step was to determine what methodology to

noise sources such as blasts (e.g., from artillery, use. The Army has chosen to classify the LACV-30 as a

armor, demolition) and rotary-wing aircraft. marine vehicle because its use is the amphibious offloading of materials from ship to shore. However, its

Noite zo,,e maps for the ICUZ program are devel- operation, construction, and noise source characteroped by the Army Environmental Hygiene Agency istics most closely resemble those of a helicopter or

(ALIlA) using the U.S. Army Construction Engineer- fixc. wing aircraft; thus the basic methodology used to

tog Research Laboratory's (USA-CERL) Integrated characterize rotary wing aircraft noise was chosen. The

Noise Contour System (INCS). This system can pro- passby noise emission measurements were made like

duce Joi lt noise /one maps for blast noise and fixed- the flyby measurements of a helicopter. Overland

and rotary-wing aircraft operations. Blast noise zone maneuvering noise emissions were characterized like a

naps are produced using the USA-CERL-developed helicopter's hover operation.

BNOISE-3.2 computerized prediction procedure, heli- ,'.

copter noise zone tnaps are developed using a USA- Mode of Technology Transfer

CLRL-tnodified Air Force NOISE MAP Computer Data developed for LACV-30 SEL vs. distance or

Pr2diction Program.' Each of these computerized speed will be entered in the INCS input data base and

prediction methods relies on three separate data sets: will be immediately available for use by AEHA and

I ) source emissions data, (2) data detailing sound other DOD installations.

propagation from source to receiver, and (3) data

defining the human and community response to the ,."

received noise. 1 TEST OPERATIONS AND _DATA COLLECTION METHODS

'Installatim Comtpatible Avoise use Zones (Department of'

the Arm. Office ,of the Adjutant General, 20 May 1981). LACV-30 Operations

'Cmstrtuion Criteria Manual. DOD 4270.1-M (Depart- The LACV-30 hovers and flies through the air a few

ment oft De .nse. 1972): Air Installations Compatible Use " " s

lones. DOD Instruction 4165-57 (Department of Defense, centimeters off the surface of water or land. Two types

1973)

Lino,ln L. Little, Violetta I. Pawlowska, and David L. *B. Homans, L. Little, and P. Schomer, Rotar. Wing AirI flind, Blast Aoise Prediction Volume If: BNOISE 3.2 Com- craft Operational Noise Data. Technical Report N-38/ADA

purer Program Description and Program Listing, Technical 051999 (USA-CERL, 1978); P. D. Schomer, Aaron Averbuch,

Report ,-98 AtA099335 (.S. Army ('onstruction Engin- and Richard Raspet. Operational Noise Data for UH-60A and

eering Research Laboratory I USA-CERL 1, 1981); R. D. Horon- CH-47C Army Helicopters. Technical Report N-131/AlI87%

Jeff, R. R. Kandukuri, and N. H. Reddingius, Community (USA-CERL, 1982).

,Vois,' k Sposuro" Resulting From Aircraft Operation. Computer 'AR 200-1, Environmental Protection and Enhancement

Program Description. Air Iorce Report AMRL TR-73-109/ (Hleadquarters, Department of the Army IHQDAI, 15 June

ADAt04821 (1974). 1982), p 7-5.

7

,- . .- : j ', -- .-,'.. -, - . , , - . . .- - - .- . . . " . . - - , . . - . . .- • -- . . . " . . . .. . . .- ,
of opelattons were pertoiuted fr this study: overwater equivalent level (LEQ) at a known distance was develpassbys and overland maneuvering. The overwater pass- oped from the maneuvering craft, and because of the

bys consisted mainly of straight line operation 1/4 measurement procedures, the equivalent spectrum was

nautical mile (nmi)* from shore at various speeds. available from the tape recordings. Table 2 lists the

Several measturements were also taken at 1/8 and 1/2 overland maneuvers.

Measurement Instrumentation

Figures 1 and 2 illustrate the microphone setup for The same measurement instrumentation was used at

the overwater passbys. Tile measurements were per- all locations (positions I through 5 at tile overwater

formed during early January 1984 at Fort Story, VA. site and positions 1 through 5 at the overland maneuThree primary microphones were located on a rocky vering site). Each station consisted of a B&K 4921

bluff about 3 in above the sea level, and about 30 in 1/2-inch quartz coated outdoor microphone system. ,.

from one another. Tile LACV-30 followed one of the The microphone signal went to the USA-CERLthree paths illustrated in Figures I and 2. These paths developed true-integrating environmental noise

were respectively 1/8, 1/4, or 1/2 nmi from the monitor and sound exposure level meter and to a

priuary measurement location and were otherwise Nagra DJ tape recorder.

parallel to a line tangent to the shoreline at the primary

measurement location. Secondary measurements were Figure 5 illustrates the typical station setup. The

made inland at locations 4 and 5 in Figure 2. only difference between sites was that the overwater

passby remote sites (stations 4 and 5) used 12-V

The overwater test consisted primarily of a set of storage batteries for power while all the other stations

passhys at tile 1/4-nmi distance, with supplemental were powered from the mobile acoustics van, condata at 1/8 and 1/2 nmi. In all passbys, the craft fol- nected to a 110-V generator or 110-V commercial

lowed tile paths indicated in Figure I, making turns power.

within 1/2 rnii of the edge of the training area. The

craft was heavily loaded with a 16-ton container during Meteorological data were gathered using the USAthe test. Operating speeds at 1/4 nmi included typical CERL tethered helium balloon system, a commercially

cruise speed (roughly 40 lb torque), maximum speed made meteorological sensor which measures wind

(roughly 48 to 50 lb torque), and low, or just below speed, wind direction, temperature, and humidity at

"hump" speed (roughly 33 to 36 lb torque). Below various altitudes. The altitudes for this set of measurehump is when the craft is plowing through rather than mnents ranged from about 3 to 45 m above the ground.

"flying" over the water.

During the passby tests only one craft was operational, so the same craft was used on two consecutive DATA REDUCTION AND RESULTS

days with two different crews. On the first day, the

I/4-nui measurements were augmented with one set

of typical cruise speed measurements at 1/2 nmi. On The acoustical data were reduced similar to the way

tile second day. the l/4-nni measurements were SEL vs. distance curves are calculated for flybys of

augmented by typical cruise speed measurements at rotary-wing aircraft and similar to how the LEQ vs.

1,!8 nrni. Table I lists the overwater passby operations distance is calculated for a hovering rotary-wing

perforined. aircraft.

Maneuvering measurements were taken as the Passby Data

opecrator steered the craft through some fairly tight Tile passby data were reduced by microphone

turns in circles and figure eights in sand dines. Figure location and operation to standard day (I 5oC and 7017

3 illustrates the overland measurement setup and the relative humidity) SEL vs. distance curves. The basic

locations of the five microphones. The craft executed data consisted of the field measured A-weighted SEL

the two maneuvers illustrated in Figure 4, around the at a site for a passby. and the tape-recorded data. The

two duties shown in Figure 3. In essence. A-weighted tape-recorded data were used to develop the time at

which the 32-second true Root-Mean-Square (RMS)

maximum A-weighted value occurred and from this ,.

to determine the 1/3-octave spectrum during that

*Onc nauticalm ilc 1828 in. 32-second period. The 32-second time period (in

7I. 7 " . , , .', . . ... &. , - --
c'J

0z

00

00
22

c~iJ

10
Table A 17 Table A 18

SEL vs. D~istance, Set 2. 1/4 ilmi at Below Hump SEL vs. Distance, 1/4 nmi at Below Hump Speed,

Speed, Traveling East and West, Jan 6 Traveling East and West, Jan 5, 6

lor)Al 11iuiibl :iveragcdl 1) Total number averaged: 21

A~erijgc ilistinci' 457-10 in Average distance: 457.20 in

\vl ccItuive humidity: 74.60 percent Average relative humnidity: 85.06 percent

\icinlpeiatLIIe: 14.50 Ci Average temperature: 13.19 0C

AVCrA w [11,iv. SOund level: 90.40 dB Average max. sound level: 93.68 dB

,\%eiige ASI- L: I 1 .39 dIB Average ASEL: 114.07 dB

Distance Average ASEL Distance Average ASEL%

(Mn) (d B) (in) (dB).

Mi122.0 50 124.8

IO)118.9 100 121.6

NO( 115.6 200 118.3

f0.9 11 500 113.5

'Io 10)I6.7 1000 109.2

Iul 10.5 2000 103.9

01191.9 5000 94.2

82.3 10000 84.9

24
Table A 13 Table A 15

SEL vs. Distance, Set 1, 1/4 nmi at High Speed, SEL vs. Distance, Over 1/4 nmi at High Speed,

Traveling East and West, Jan 5 Traveling East and West, Jan 5, 6

Total number averaged: 12 Total number averaged: 24

Aveiage distance: 45 7.10111 Average distance: 457.20 m

Average relative humidity: 93.70 percent Average relative humidity: 85.50 percent

Aveiage temperature: 11.,60 0

C Average temperature: I 2.700

C

Average mnax. sound level: 94.40 dB Average max. sound level: 90.95 dB

A~c~a~ve ASEL: 1 11.23 dB Average ASEL. ,07.55 dB

Distance Average ASEL Distance Average ASEL

(in) (d8) (in) (dB)

5o 122.1 s0 118.3

1(10 118.9 100 115.1

2Loo 115 5 200 111.8

M'110.6 500 107.0

1 (10( 106.1 1000 102.7

2000 100.8 2000 97.5

oo92.1 5000 89.0

100 00 85.4 10000 82.0

Table A 14 Table A 16

SEL vs. Distance, Set 2, 1/4 nmi at High Speed, SEL vs. Distance, Set 1, 1/4 nmi at Below Hump

Traveling East and West, Jan 6 Speed, Traveling East and West, Jan 5

[otal number averaged: 12 Total number averaged: 12

Average distance: 457.20 rn Average distance: 457.20 mn

Average relative humidity: 77.30 percent Average relative humidity: 92.90 percent

..\erage temperature: 13.80 0C Average temperature: I 2.20 0C

Avera~re max. sound level: 87.51 dB Average max. sound level: 96.14 dB

Average ASEL: 103.88 dB Average ASEL: 116.08 dB

Distance Average ASEL Distance Average ASEL

(ml) (dB) (in) (dB)

5(1 114.5 50 126.8

111(1 111.4 100 123.6

200 108. 200 120.3

5001 103.3 500 115.5

1 000) 99.2 1000 111.1

20100 94.2 2000 105.7

50001 85.8 5000 96.0

10000 78.5 10000 86.7

23

%
Table A9 Table AI l

SEL vs. Distance, Cruise Speed, Traveling East, for All SEL vs. Distance, Cruise Speed, Jan 5, 6, Traveling

Distances, Jan 5, 6 East and West, for All Distances

Total number averaged: 21 Total number averaged: 45

Average distance: 556.47 in Average distance: 535.22

Average relative humidity: 85.66 percent Average relative humidity: 85.10 percent

Average temperature: 12.95 0C Average temperature: 13.01 0C

Average inax. sound level: 93.61 dB Average max. sound level: 92.47 dB

Average ASEL: 109.88 dB Average ASEL: 110.13 dB

Distance Average ASEL Distance Average ASEL

(M) (dB) (M) (dB)

50 122.7 50 122.9

100 118.7 100 118.8

200 115.0 200 114.9

500 110.0 500 110.0

1000 105.6 1000 105.7

2000 100.1 2000 100.4

5000 90.6 5000 91.4

10000 82.0 10000 83.5

Table AlO Table A12

SEL vs. Dista-ce, Cruise Speed, Traveling West, for All SEL vs. Distance for 1/8 and 1/4 nmi at Cruise Speed,

Distances, Jan 5, 6 Traveling East and West, Jan 5, 6

Total number averaged: 24 Total number averaged: 33

Average distance: 516.63 in Average distance: 397.34 m

Average relative humidity: 84.62 percent Average relative humidity: 81.98 percent

Average temperature: 13.06°C Average temperature: 13.52°C

Average max. sound level: 91.48 dB Average max. sound level: 92.46 dB

Average ASEL: 110.36 dB Average ASEL: 109.78 dB

Distance Average ASEL Distance Average ASEL

(in) (dB) (M) (dB)

50 123.1 50 119.6

100 118.8 100 116.4

200 114.8 200 113.1

50) 110.0 500 108.3

1000 105.7 1000 104.0

2000 100.6 2000 98.8

5000 92.0 5000 89.8

10000 84.8 10000 82.1

• -;-'-~~~~~~~~~~~~~~~~~~~~~~.'/--.......-' ........ . ... ."-". .. .....-..-.. . ..- '. ..- ,".'.-". .-.

• % ° ). . = , . .-- , . i " "I" " " " ) " °

" •- ' . . ." . " . .- ~ - ° . " • " •'-.
Table A5 Table A7

SEL vs. Distance, Set I, Averaged Over 1/4 nmi at SEL vs. Distance, Set i, at Cruise Speed, for All

Cruise Speed, Jan 5, 6, Traveling East and West Distances, Jan 5, Traveling East and West

Total number averaged: 12 Total number averaged: 24

Average distance: 457.20 in Average distance: 685.80 m

Average relative humidity: 92.87 percent Average relative humidity: 93.28 percent

Average temperature: 12.330 C Average temperature: 11.970 C

Average max. sound level: 94.95 dB Average max. sound level: 93.72 dB

Average ASEL: 111 .48 dB Average ASEL: 111.30 dB

Distance Average ASEL Distance Average ASEL

(M) (dB) (m) (dB)

50 122.4 50 127.2

100 119.2 100 122.2

200 115.8 200 117.8

500 110.8 500 112.8

1000 106.4 1000 108.3

2000 101.1 2000 103.0

5000 92.0 5000 93.8

10000 84.3 10000 85.9

Table A6 Table A8

SEL vs. Distance, Set 2, Averaged Over 1/4 nmi at SEL vs. Distance, Set 2, at Cruise Speed, for All

Cruise Speed, Jan 6, Traveling East and West Distances, Jan 6, Traveling East and West

Total number averaged: 12 Total number averaged: 21

Average distance: 457.20 m Average distance: 363.13 m

Average relative humidity: 74.60 percent Average relative humidity: 75.76 percent

Average temperature: 14.50'C Average temperature: 14.200 C

Average max. sound level: 89.27 dB Average max. sound level: 91.04 dB

Average ASEL: 108.14 dB Average ASEL: 108.80 dB

Distance Average ASEL Distance Average ASEL

(iM) (dB) (M) (dB)

50 118.8 50 118.0

100 115.6 100 114.9

20o 112.4 200 111.6

500 107.6 500 106.8

1000 103.5 1000 102.6

2000 98.4 2000 97.4

5000 89.5 5000 88.6

10000 81.5 10000 80.8 .

21

... ' , ................... ° . .-.... .-........... . -.. - ° ..-°.. . -'7 , .' . -- a%

........ . . . .. . . . . r- w-a'' ,
APPENDIX:

SEL VS. DISTANCE TABLES FOR MICROPHONES 1, 2, AND 3

AVERAGED OVER VARIOUS TYPES OF OPERATIONS

/.

Table A l Table A3

Key to Appendix Tables SEL vs. Distance Averaged Over 1/2 nmi at Cruise

Table Date Speed Distance Direction Speed, Jan 5, 6, Traveling East and West

A2 Both R 1/4 Both Total number averaged: 12

A3 Both (5 Jan)* R 1/2 Both Average distance: 914.40 m

A4 Both t6 Jan)* R 1/8 Both Average relative humidity: 93.70 percent

A5 5 Jan R 1/4 Both Average temperature: I 1.600C

A6 6 Jan R 1/4 Both

A7 5 Jan R All Both Average max. sound level: 92.50 dB

A8 6 Jan R All Both Average ASEL: 111.12 dB

A9 Both R All IA10 Both R All W Distance Average ASEL

All Both R All Both (M) (dB)

A12 Both R 1/8 and 1/4 Both

A13 5 Jan H 1/4 Both 50 132.0

A14 6 Jan H 1/4 Both 100 125.2

AIS Both H 1/4 Both 200 119.7

A16 5 Jan L 1/4 Both 500 114.7

Al 7 6 Jan L 1/4 Both 1000 110.3

A18 Both L 1/4 Both 2000 104.9

5000 95.6

I Wo .087.5

Table A2 Table A4

SEL vs. Distance Averaged Over 1/4 nmi at Cruise SEL vs. Distance Averaged Over 1/8 nmi at Cruise

Speed, Jan 5, 6, Traveling East and West Speed, Jan 5, 6, Traveling East and West

Total number averaged: 24 Total number averaged: 9

Average distance: 457.20 in Average distance: 237.70 m

Average relative humidity: 83.73 percent Average relative humidity: 7730 percent

Average temperature: 13.420C Average temperature: 13.80 0C

Average max. sound level: 92.11 dB Average max. sound level: 93.41 dB

Average ASEL: 109.81 dB Average ASEL: 109.68 dB

Distance Average ASEL Distance Average ASEL

(m) (dB) (in) (dB)

50 120.6 50 117.0

100 117.4 100 113.8

200 114.1 200 110.5

500 109.2 500 105.7

1000 104.9 1000 101.4

2000 99.7 2000 96.2

5t)00 90.8 5000 87.3

10000 82.9 10000 79.8

20

,-. ...- ,. ,, ",,, . ..... ....-. _- -. .... _- -.-. .-.-. , ,.- . ..- -,.. -.- .- -,-. -- ,\ -: ,,,
Table 3 2. The relation between operator technique and

LACV-30 Operational Noise Level vs. Distance Data noise should be constantly stressed. An "overly en- -

thusiastic" type of operation creates more noise and

Cruise Speed, Maneuver is less efficient" this type of operation should be

Hligh Speed.* Below Flump Equivalent discouraged. Similar problems (along with comparable

Distance SEL Speed* SEL Level reductions in efficiency) are common with helicopters

(m) (dB) (dB) (d) and construction equipment. The solution is stress on

SO 122.9 124.8 93.5 the importance of efficient, neighborly operation of

100 118.8 121.6 87.3 the craft.

200 114.9 118.3 80.8

500 110.0 113.5 71.8 3. Since weather conditions play the major role in 10oo0 105.7 109.2 64.3 sound propagation and the resulting loudness in the

2(000 100.4 103.9 56.1

5000 91.4 94.2 44.7 community, weather and sound monitoring may be

I00o00 83.5 84.9 36.2 used to adjust operations. For example, time-of-day

requirements can be pegged to measured conditions

*In gencral, iust the cruise speed data should be sufficient for and time of year.

all operations. In certain instances. one may need to separate1., use the below hump speed data.

passbx measurements, levels varied by as much as 10

dB from one day to the next because of sound propagation conditions. CONCLUSION

Potential noise mitigation methods include the

fllowing: The report gives the sound exposure level vs. distance curves for the LACV-30 for various speeds and

1. The prop noise can be reduced (probably 10 to operations over water and over land. These data

20 dB) by a redesigned prop and possible inclusion of supplement earlier rotary wing aircraft data developed

a shroud. Since machinery noise is generally a sign by USA-CERL and used in the USA-CERL modified

of inefficiency, a quieter prop would likely be more version of the Air Force NOISEMAP Prediction

ftle! effiCient. Program.

'

19 '"

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Ll

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x2

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CjC

z- 4c

0

-w Z

tot

ow

Q a

I.

o~8 0 WC 00I m ,oOd 3A31LN31AIAO ifO~S~9P) 

Iz

pw

180

0 0 0

m........................................................................

. . d . .O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
060

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00 0~ 0 

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lGP) -13S p9445.19M-V

17o

:"o . . .... . .-.. . . - , " - t 

,'x~ ll z .-,, .- "' .. . -. , , .' . ,-,, .',,- - ,-, . , ,'. .- -'.' '-' ',,' '..,,. ..,,,.-. .. ,f,' .. ,. ,

_ ' -.I~d ;.-. .;: ... . -_.z - - x2 , -.. . - ., -.. , .... -,. ..,-, .,.-,., . .. -. .,,-..
Inland Measurements other microphones were 275 In from the center. The

Measurements were also made at locations 4 and 5 resulting I/3-octave spectra were also corrected for an

inland. Location 4 was about 300 in inland and at additional 85 in of atmospheric absorption (temperaroughly the same elevation as microphones 1, 2, and 3 ture and relative humidity did not change much during

while location 5 was 800 m inland atop a 15 m hill. the I day these data were gathered). These 1/3-octave

Comparing the measured SEL at the inland micro- spectra were similar from operation to operation and

phones with the corresponding composite prediction were averaged (on an energy basis) over all the opera.

curves based on data gathered with the shoreline tions performed to form an overall measured equivamicrophones showed the general trend (as expected) of lent 1/3-octave spectrum at a distance of 275 m from

excess attenuation due to propagation over ground, in the center of a maneuvering area for a maneuvering

addition to normal geometric spreading. This excess craft. This 1/3-octave spectrum (Figure 7) was conattenuation varied between 0 and 16 dB. About 8 or verted to an A-weighted LEQ vs. distance using the

•.. 9 dB was a typical value at station 4. For station 5, methods of ANSI SI.26-1978 to vary the 1/3-octave

on a hill top. the iesults were quite mixed. In one levels in terms of atmospheric attenuation (correcting

instance for below hump speed operation, the hill- to 15°C and 70 percent relative humidity) with

top measurements actually exceeded the value pre- distance and a factor of 20 log D/Dm to vary the overdicted by the shoreline microphones by about 3 1/2 all level with distance.

dB. Since this location was on a 15-in hill, refraction

out of a shadow zone may have contributed to high Table 3 contains the overall results. The second

levels, with ground reflection less of a factor, column is the A-weighted SEL vs. distance (where

distance is point of closest approach) for a craft

For predictions of overland passby noise levels, it traveling at cruise speed or high speed on the water. the

is recommended that 8 dB be subtracted from the third column contains the below hump speed SEL

overwater SEL vs. distance prediction when the land data, and the fourth column contains the equivalent

site is substantially inland and the elevation is near A-weighted level vs. distance (from the geometric

sea level. When the land site has elevated terrain or the center of the maneuver area) for a craft maneuvering

receiver is at a high location, then diffraction is more on land. These data have been entered into the data

important than excess ground attenuation and nothing base of the INCS and are available for the development

should be subtracted from the overwater SEL vs. of noise zone maps by AEHA and others.

distance curves.

Difrerent Speeds A NOISE SOURCES AND POTENTIAL

: Comparisons were also made as a function of speed. MITIGATION METHODS

In addition to the normal cruise speed, data were

gathered for high and below hump speed. Figure 7

compares these three composite data sets. The below Several reasons for high noise emissions fiom the

hump ,,.LACV-30 speed creates a slightly higher SEL than does were identified dLIIg the coutse ot data

the cruise speed. The high speed SELs are slightly gathering and are included here as useful intornatlon

lower than the cruise speed SELs. In general, overwater LACV-30 operations can probably be adequate- The measured passby levels of approxumatel. 1 10

ly represented by the cruise speed composite curve, dB (A-weighted SEL) at 1/4 and 1/2 nmi indicate this

but In critical instances one may wish to use the below is a very noisy craft. The spectra (Figure 8) show that

hump composite for this mode of operation. the primary noise source is at 100 Iz, which is the

blade passage frequency of the props.

Overland Maneuver Data

v The overland maneuver data were analyzed by Operator technique is also a factor in the noise

finding the equivalent 1/3-octave spectrum levels for generated by the LACV-30. at least over land. During

the entire maneuver. Because microphone 5 was on a the maneuver tests, the second operator moved the

" " hill and closer to the center of the array than micro- craft more quickly but with less control than did the

phones I through 4. 3.1 dB were subtracted from first, taking longer to perform the maneuvet ind

microphone 5's spectrum to make it equivalent (in creating higher noise peaks.

terms of distance) to the other four spectra. The

3.1 -dB figure was calculated as 20 log 275/192 since Weather conditions play a major role m the noise

the hill position was 192 in from the center while the which propagates from the LACV-30. l)urmng the

16

• %-........ :.'.....-.----...--.".-:- . .:.' - .':..< :-:-": 7 : .::-. -- :-

. .. . . .. . . , . . . . . . . . - . . .. . . . . . '
2

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5- 0

o

U- - 0

N

o00

-- 0

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" 0

NN

' .""- ""; ". ." - - " . ." - .""""" '"" . ." ""- ."""". . """ " ,'''-.- "'' -" - "'' ': ,,"'" - :," '"0" " ' • l " o " .," o " = " * ° * " ." . = * .* o ° " o* o • o - • . . . . • , • " . -' • • 0i =
9-'.l

S.x

B 8 K 4921

Outdoor Microphone System

1*

.

USA-CERL True Integrating Nagra DJ

Environmental Noise Monitor Tape Recorder

and Sound Exposure Level

Meter

Figure S. Measurement equipment at a site.

- contrast t) 2 seconds for aircraft) was used because of passbys. The data were gathered on two consecutive

- the LACV-30's slow speed and long passby time days. Sound propagation from ship to shore was much

" compared to aircraft speed.* Each measured SEL and stronger on the first day than the second, resulting in

1/3 octave spectrum was then developed into an SEL higher sound levels recorded on the first day. On the

vs. distance curve using three factors. These factors first day, readings were also taken 1/2 nmi from shore

were the l/3-octave band absorption values in ANSI and on the second day 1/8 nmi from shore.

SI .26-1978,6 the factor for the spherical spreading of

sound (20 log D/Dm where D is the distance in ques- Except for the measurements made at 1/2 nmi the

tion and Dm is the measurement distance), and the first day, the general results were fairly consistent from

factor 10 log (Dm/D) to account for the duration one distance and day to the next. On the first day,

change in SEL with distance. however, sound propagation conditions were such that

Shoreline Measurements the measurements made at 1/2 nmi were virtually

The various site and distance data were arrayed for identical to the results at 1/4 nmi; there was no change

a given operation, such as normal power cruise. As with distance.

indicated above, primary use was made of data gather.

ed by the three shoreline microphones and the 1/4 nmi The appendix tabulates various SEL vs. distance

combinations calculated. Figure 6 illustrates the

composite SEL vs. distance for 1/4 and 1/8 nmi, *The data were also analyzed using a 1/2-second time calculated using microphones 1,2, and 3, during cruise

period. Using this very short time only resulted in changes of a speed on the first and second day. Figure 6 also shows r

few tenths of a decibel in the SEL vs. distance curves (Appendix). just the l/2-nmi data and a composite of all the cruise

'American National Standard Institute (ANSI) Standard speed data. The l/2-nmi data raise the composite

S1.26-1978, "Method for the Calculation of Absorption of average by 2 to 3 dB over what it would otherwise be.

Sound by the Atmosphere." These data were included since they were valid.

14

. ... ... • 6%,o... *. . . . ". ' . '. .".° . . - " . & . . ." . .'. ,9.99"99'*.9&9*• ' 

"

9. .. 9- .. . .9 . ,9..' 9... . '9 , .9. ', .. '. ." .', . . " . .. , , .. -.' - ,,.'\-. ."'.. -.- ''. '' ./ -. "'. .- ,, .'" '% .1

¢ .-.-..- .- ...-.. .. " ."" 9 . . 9' - . - . . - : - -v ,. - - . " -," ' ' - . ' - r.,,... ._ .,,_ ... .. - . ' , '
Start and End at Center I * 1Figur Between Dunes

• ~"Figure 8" ;'Y

Loop"

Figure 4. Land maneuver patterns for the LACV-30

N

Table 2

Overland Maneuvers

Run No.* Set No. Maneuver**

33 3 "Fig. 8"

34 3 "Fig. 8"

35 3 2-loop

36 3 2-loop

37 4 2-loop

38 4 2-loop

39 4 "Fig. 8'"

*A typical land maneuver took 15-20 minutes

**See Figures 3 and 4 for definition of land maneuvers

13

4 ............................... .I. .. . .. . .
ci Yb

00

0

41c.

00

, U

Ij L CC

cc

wuw
Table 

I

Overwater Passby Operations

a. Set I, MP Station. 5 Jan 84

Distance

Run No. Direction (nmi) Speed*

I W 1/4 

R

2 E 1/4 R".:

3 W 1/4 /4 R

5 E 1/4 L t7

6 W 1/4 

L

7 E 1/4 

L

.8 W 1/4 L .-

1

9 E 1/4 H 

j 10 W 1/4 H

11 L 1/4 

H 12 W 1/4 H

13 E 1/2 

R

14 W 1/2 

R

15 E 1/2 

R

16 W 1/2 

R

b. Set 2, MP Station, 6 Jan 84

17 E 1/4 

R

18 W 1/4 

R

19 E 1/4 

R

20 W 1/4 

R

21 E 1/4 

L

22 W 1/4 

L

23 E 1/4 

L

24 W 1/4 

L

25 E 1/4 

H

26 Aborted 

-

27 E 1/4 

H

28 W 1/4 

H

29 E 1/4 

H

30 W 1/8 R

31 E 1/8 

R

32 W 1/8 R

•R cruise speed

L = below hump speed

H = high speed

I].?

~. -o ~ *. .

..-

-..

11 "'-
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DTIC