NACA Report 648

to which the Biot-Savart equation is applicable. The actual sheet, however, does not extend ..... of lhe in,luted tlow generally being negligible compared with the free- stream velocity ... of this integral ..... WAKE CHARTS AND FORMULAS.
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REPORT

DESIGN

CHARTS

ANGLES

AND

WAKE

PLAIN

By ABE Langley

111 ():_4--3!_--

I

FOR

AND

No. 648

PREDICTING

CHARACTERISTICS FLAPPED

SILVERSTEIN Memorial

DOWNWASH

and

Aeronautical

WINGS

S. KATZOFF Laboratory

BEHIND

NATIONAL

ADVISORY

COMMITTEE

HEADQUARTERS,

NAVY

BUILDING,

LABORATORIES, Created study act

of

by

the

act

of

Congress

problems

approved

of

March

approved

flight

2,

1929.

S.

Code,

The

members

3,

Title

1915,

50,

are

FIELD,

for

Sec.

AERONAUTICS

WASHINGTON,

LANGLEY

March

(U.

FOR

the

Its

by

C.

supervision

151).

appointed

D.

VA.

the

and

direction

membership

was

President,

and

of

the

increased

serve

as

such

scientific to

15

by

without

compensation. JOSEPH

S.

AMES,

Ph.

Washington, WII.LIS RAY Chief,

D.

D. GREGt;,

United

WILLIAM

D.,

P.

SYDNEY

Chairman,

Eng.,

Vice

D.,

States

Chairman,

Weather

MACCRACKEN,

Washington, G.

J.

D.

Exeeuti_e

DENIS

Commillee,

Bureau. D.,

Vice

('hairman,

So.

Director, B.

Chief, HARRY Port

National COOK, Bureau

F.

Bureau

Rear of

of

Aeronautics,

Navy

M.

Washington,

States

Department.

Long

N.

E.

REID,

ROBINS,

W.

LEWIS,

Engineer-in-Charge, J.

Director F.

VICTORY,

Langley IDE,

Technical

of

Division,

WARNER,

Aeronautical

Memorial

of

Research

Needs of

Prevention

Unified scientific

AERONAUTICAL

Aeronautical in

problems

conduct,

for

all

on

the

of

flight.

General,

Field,

United

States

Army,

Department.

Laboratory,

Europe,

Paris,

LABORATORY

of

Research of of

Military

and

Langley

AIRCRAFT

STRUCTURES

AIRCRAFT

ACCIDENTS

Civil

AND

fundamental

DESIGNS

Aviation

Programs

Duplication of

Inventions OFFICE

OF

AERONAUTICAL

INTELI,IGENCE

WASHINGTON,

agencies,

Field,

France

Problems

VA.

research

Wright

D.,

INVENTIONS

Consideration

FIELD,

Corps,

Air

Research

MATERIALS

Allocation

LANGLEY

States

COMMITTEES

Preparation

MEMORIAL

Commerce. United

Ohio.

FOR AIRCRAFT

Coordination

LANGLEY

Sc.

of Air Corps, War WRIGHT, Sc. D.,

AERODYNAMICS AIRCRAFT

of

General,

Secretary

Assistant

TECHNICAL

PLANTS

Department

Brigadier

Y.

JOHN

POWER

Navy,

Ohio.

Dayton,

Island,

JOlIN J.

Chief ORVILLE

Navy,

A.,

GEORGE

HENRY

W.

P.

States Department.

LL.D.,

Greenwich, Conn. OSCAR WESTOVER, Major

Standards. United

United Navy

City.

Mat6riel

EDWARD

Admiral,

GUGGENHEIM,

LINDBERGH,

Dayton,

D., Institution.

Captain,

MULLIGAN, J. S. D., Director of Air Commerce,

AUGUSTINE

Executive

C.

ABBOT,

A. York

Army, Chief

Secretary, Smithsonian LYMAN J. BRIGGS, Ph. D., ARTHUR

KRAUS,

of Aeronautics,

CHARLES

Chairman,

New

C. So.

Committee, CIIARLES

M.

Bureau

Baltimore, Md. I)AVID W. TAYLOR,

of and

D. C.

Collection, classification, dissemination of scientific

nical

information

on

compilation, and tech-

aeronautics.

Va.

REPORT

No.

648

DESIGN CHARTS FOR PREDICTING DOWNWASH ANGLES AND CHARACTERISTICS BEHIND PLAIN AND FLAPPED WINGS l]_,

+\I+I:

_II+\I,:RSTEIN

SUMMARY

l+,'quatiol_s aml desigl_ c/torts are given for predicting the doumwash al+gles a_(1 the wake charachristics .for power-off eoT+ditio_+s behimt plain and flapped wings oJ the types used in modern desig_ practice. The dou,mrash charts cover the cases of elliptical wings amt wil_gs of taper ratios 1, 2, 3, aTM 5, with aspect ratios of 6, 9, arid 12, hadr_g flaps em, eri_g O, gO, 70, aTM 100 }>ereel_t of the ,_pa_. Curves of the spa_ load distributio_+s for all these cases are i*wluded. Data o_ the lift aml tile drag q[ flaplJed airfoil secti+ms aml curces for fiI_di,_g the coldribution of the flap to the total wb_g lljt .for diff_re?it types of flap al_dJor the entire ra,ge of flap spans are ah.o inel'uded. The wake width, and the distribution of dyrmmie pressure across the wake are given in terms of the profile-dra 9 eoeflieiel_t and the distance behind the whig. A method of estimating the wake position is olso give_+. The equatlons and the charts are based on theory that has been show_t ia a previous report to be in a.qreemeT_t with experime_ t. INTRODUCTION In a recent for predicting for power-oil' loading. The

paper (reference 1) methods are developed

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