NASA C*'INTRACTOR REPORT 177340

STUDY FOR PREDICTION OF ROTOR/

WAKE/FUSELAGE INTERFERENCE

PART II: PROGRAM USERS GUIDE

(llASA-CB-I"/?3_0-Vol.2) $TODI FO_ PRZDZCTION

OF ROTOR/MAKE/FUSELAGE INTSHFE_ENCE. PART

2: PROG_AB USERS GUIDE Final _epoLt, I

Jun. 1980 - I Mov. 1983 (Analytical Bethods,

Inc., _edmcnd, bash.) 9_ F HC AO5/HF R01

D. R. Clark

B. Maskew

G3/U 1

H85-22347

Uncla s

_U170

CONTRACT NAS2- 10620

NoVember 1983

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NASA CONTRACTOR REPORT 177340

b

rSTUDY FOR PREDICTION OF ROTOR/WAKE

FUSELAGE INTERFERENCE

PART II: PROGRAM USERS GUIDE

D. R. Clark

B. Maskew

Analytlcal Methods, Inc.

2047 - 152nd Avenue, N.E.

Redmond, WA 98052

Prepared for

Ames Research Center

under Contract NAS2-10620

,_4nl_onalAeronautics and

,Space Administration

Ames Research Center

Moffett Field. California 94035
TABLE OF CONTENTS

section

LIST OF FIGURES .....................

1.0 INTRODUCTION ...................

2.0 GENERAL PROGRAM ARRANGEMENT .............

3.0 PANEL _ODEL DEFINITION (Card Sets 9 through 16)

3.1 Body Panelling

3.1.1 Conventional Input .

3.1.2BodiesofRevolution

3.1.3 Lifting Surfaces--Type-3 Patches ....

3.1.4 Rotors--Type-4 Patches .........

4.0 WAKE INPUT

4.2 Separation Line Specification. Card Sets 9

through 23 ...............

4.2.1 Wake Definition for Type-1 Wakes ....

4.2.2 Wake Definition for Type-4 Wakes on

Bodies .................

4.2.3 Wake Definition for Type-4 Wakes on

Rotors .................

5.0 ROTOR BLADE ELEMENT MODEL INPUT DESCRIPTION ....

5.1 Rotor Patch Identifiers (Cards R1 and R2) • • •

5.2 Output Print Controls ...........

5.3 Iteration Controls (Card 14) .........

5.3.1 Blade Flapping . . . • .........

5.3.2 Rotor Lift ...............

5.3.3 Rotor Moments .............

5.4 The Blade Element Model Geometry (Card Sets R6,

R7, RS, R9 and RI0) ..............

iii

i

2

5

13

18

24

30

30

33

42

45

51

51

51

52

52

53

53

53
TABLE OF CONTENTS (CONCLUDED)

5.5 Rotor Performance and Control (Cards Rll, R12,

R13 and R14) ................. 55

5.5.1 Rotor Speed and Flapping (Card Rll) . . 55

5.5.2 Rotor Blade Cyclic Control (Card R12).. 55

5.5.3 Rotor Loads and Moments (Cards RI3 and

RI4) ................. 56

5.5.4 Airfoil Data Sets (Card RIS, Card Sets

R16) .................. 56

6.0 INPUT DATA DECK BLOCKING AND VARIABLE LIST ..... 57

6.1 Input Summary ................. 57

6.2 Input Variable List . . . . . . ...... 58

6.3 Rotor Input Data Deck Description _ ...... 65

7.0 REFERENCES ...................... 73

APPENDIX : Sample Case

(a) Input

(b) Output (Abridged)

II

iv
LIST OF FIGURES

o

1

2

3

5

6

7

9

i0

2i te

General Program Schematic .........

Rotor Calculation Schematic ........

3

4

Conventional Body Input

(a) Patch-Section-Point Breakdown .......

(b) Typical Input Data Set ..........

6

7

Typical Wing Panelling

(a) Point Input and Tip Closure Schematic . • •

(b) Typical Wing Input ............

Sample--Body of Revolution--Nacelle

(a) Patch Section Points Schematic .......

(b) Nacelle Input List ............

9

10

14

15

Simple Elliptical Fairing

(a) Basic Set-up ...............

(b) Input Data Listing ............

16

17

Sample Lifting Surfaces

(a) Simple Tail--Schematic .....

(c) More Complicated Tail--Schematic

(d) More Complicated Tail Input Details ....

20

21

22

23

Main Rotor Modelling

(a)b) Schematic. Input Details _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

25

26

Tail Rotor Modelling

(a) Schematic .................

(b) Input Details ...............

Wake-Grid-Plane Definition

28

29

(a) Simple Isolated Rotor ...........

(b) Embedded Body ...............

31

32

iii
LIST OF FIGURES (CONCLUDED)

_o

11

12

13

14

15

16

17

18

Title _o

Type-i Wake-Wing Separation Lines ..... 34

Wake Trajectory Definition ........ 36

Wake Shedding Schematic--Multi-line Input . 38

Multiple Patch Wakes ........... 41

(a) Type-4 Wake on Nacelle • • • 43 cb,Type-_separat,dwakeonBio_k_d_lo_

Rotor Head ................ 44

Rotor Wake Specification--Simple Isolated

Rotor ................... 46

Rotor Wake Input Schematic with Fuselage

Present . ................ 49

Rotor Blade Element Model--Schematic • • • 54

iv
1.0 INTRODUCTION

Because the body/rotor program is a direct development of

Program VSAERO (Ref. 1), no attempt will be made here to describe

in detail the set-up and operation of these features of the

present analysis which are in common with the original program.

For the description of the non-rotor components, the development

of the panelling schemes and the discussion of the undez_lying

theory, the reader is referred to the original reports., The

discussion here will place the rotor elements in the basic framework provided by VSAERO and will concentrate on a description of

how rotary wing aircraft may be built up and placed in space

using the flexibility inherent in the program geometry routines.

The body/rotor code outlined here is directly related to the

1000-panel version of Program VSAERO delivered to the NASA Ames

Research Center and installed on the C_AY computer. The computation times are consistent with those published in the o_iginal

Program User's Guide for cases with complicated wakes if allowance is made for the rotor calculation by multiplying by a factor

of roughly 1.3.

1
2.0 GENERALPROGRAMARRANGEMENT

The rotor analysis is contained in a subroutine of program

VSAERO and is called whenever a component is identified as

belonging to a type 4-patch. Since the rotor blade element

analysis responds to changes in inflow velocity, the rotor calculation is placed within the wake relaxation loop structure. This

is highlighted in the solution block diagram in Figure I. A

typical solution would proceed as follows.

A. From input data, program assembles body and rotor panel

model.

B. Program forms surface panel influence coefficients.

C. Initial wake shape is constructed.

Do On first pass, program sets up blade element model, and

assuming uniform inflow, calculates rotor loads and moments and (if requested) trims rotor. On subsequent

iterations, inflow calculated on previous cycle is used.

From calculated loadings, program evaluates rotor disc

flow through velocities (local momentum balance) and

doublet strength (to feed the rotor wake) and passes

these back to the panel model.

E. Solve for body panel singularity strengths.

F. Calculate new wake shape and determine new inflow velocities at rotor panel centers.

G. Return to D to complete wake relaxation cycle.

He If requested, carry out viscous/potential flow iteration

re-entering at D.

I. Termination.

Embedded within the rotor performance module are nested

loops which control the blade flapping, rotor thrust (with collective pitch change) and rotor moments (with cyclic pitch

change). These are outlined in the rotor calculation block

diagram in Figure 2. At each azimuth location, the section loads

are calculated for every station out along the blade. These are

integrated radially to form the azimuthal totals. The blade is

then moved to the next azimuthal location with flapping motions

in response to any out of balance at the first position added.

The blade is cycled around the azimuth until blade flapping has

stabilised. The thrust is checked against the desired level and

the collective pitch adjusted. Once the required thrust has been

achieved, rotor moment trim _s checked and adjusted if required.

2
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3.0 PANEL MODEL DEFINITION (Card Sets 9 through 16)

3.1 Body Panellinu

3.1.1 Conventional Input

Body panelling, including any lifting components w_. _

present, follows exactly the format set down in the Progr:

VSAERO User's Guide, Ref. i. As a result, the body can be maa_

up of any convenient combination of panels, patches and components. In the VSAERO hierarchy, the panel is the smallest

element controllable by the user. A patch is a collection of

panels in a regular array and a component is an identified group

of patches taken together for the evaluation of force and moment

totals. Components may be further grouped into assemblies.

The body shape may be entered in several ways, depending on

its complexity and on the way in which the shape data is available. Conventionally, the body is defined with a set of loft

lines which are generally cut at constant body locations, station

(x), buttline (y) and waterline (z). Figure 3 illustrates how a

typical body may be first broken into patchesgFigure 3 (a), and

then inputr Figure 3(b). The patch allocation is made so that

the different regions of the body may be represented by panelling

of the appropriate density, high in regions of particular interest, low in other areas bearing in mind that within a patch,

the panels form a regular array with the same number of panels in

each row and column. Consequently, patch boundaries almost always occur where large changes in body cross section are present

and in regions where, away from areas of interest, panel densities are being reduced for reasons of economy.

In the case of the body used in this illustration, the shape

was defined with a series of station (constant x) cuts. following the VSAERO User Document, Ref. i, each section is defined

by a series of points located in a local axis system in the

global coordinate system. The data set defining each section

contains a header card which contains the origin of the local

axis system in the global coordinate system, the scale and orientation of the section (section may be scaled and/or rotated to

ease input), and indicator cards which alert the computer to the

way in which the data is being input and which indicate whether

the section is internal to or closes a patch and provide information on how the patch is to be divided up. The header card is

then followed by the string of points defining the section,

together with node cards which alert the computer to the way in

which the surface is subdivided, to any changes in surface curvature at junctions, and to the termination of the string.

Program VSAERO offers the user great flexibility in the ways

in which the shape may be input. Individual defining sections

may be input in either the x (with y and z), y (with x and z), or

z (with x and y) planes or in generalized x, y and z coordinates.

Any other previously defined section may be automatically copied
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or polar coordinate sections are available.

The data sets for successive sections are stacked to form

the input data set for a patch and the way in which they are

stacked is of particular importance. Sections should be stacked

in order and in a direction consistent with the way in which the

points are input along each section. In the example shown in

Figure 3, the _oints on each section were input up along the

profile on the stark _ard (positive y) side toward the top centerline and although the input points do not necessarily dictate

panelling directly, the direction of input determines the order

of the panel, with the first section input making up side 1 of a

patch, and the panels numbered in the direction of the input

points. Since program VSAERO requires that panels and patches

have an anticlockwise corner point order when viewed from outside

with the bottom to top input scheme used in Figure 3, the sections must be stacked from front to rear. If the _ had been

entered from top to bottom, then the section input order would

have been reversed and the patch would have been defined with

sections input first at the rearmost edge of the patch and

working forward.

Input sections need not have the same number of defining

points. However, when instructing the program on how the section

should be subdivided, it should be remembered that a patch is a

regular array and all colun_ns must have the same number of

panels. This is determined by the user properly setting the

appropriate dividing instructions (the node cards) in the section

input string.

Wing sections are conventionally input as shown in Figure 4.

Using the same format as outlined for bodies above and starting

with the lower trailing-edge point, the surface is input point by

point working forward toward the leading edge, around the leading

edge and aft over the upper surface. As with the body input

described above, node cards are inserted to delineate regions of

differing panel density or changes in surface curvature. For

in3tance, in the example shown, the panelling is required to be

more dense close to the leading edge. This is achieved by inserting a node card with a value of NODEC-I at the leading edge

(indicating the end of a region but maintaining surface curvature) and using values of the distribution controls, INTC-2, at

the end of the lower surface and INTC-I at the end of the upper

surface. Following this procedure, sections should be stacked

from root to tip if only the starboard (positive y) side of the

vehicle is being modelled.

Although a panel is the basic element in modellng the surface and the solution proceeds with the strength of the sing_-

larlty used to represent the panel as the unknown, the patch is

the most conveniently manipulated unit. Patches may be constructed and moved into place to represent the configuration in any

way convenient to the user. They may be ordered in any way

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a configuration to be made by removing a feature and simply

plugging in one or more replacement patches to remodel the

vehicle.

Summarising, the input llst for a typical surface patch

would be as outlined below. The names used for the data items

are those employed in the Program VSAERO User's Manual. The

terms "chordwise" and "spanwise" can be considered to represent

directions along the input section and along the patch length

respectively. For completeness, they are also defined here.

IDENT Patch type 1-Wing

2-Body

3-Lifting Surface (Neumann)

4-Rotor

KOMP

KASS

Defines component and assembly to which

patch belongs

PNAME Patch title

STX, STY, STZ

SCALE, ALPHA, BETA

INMODE

NODES

Section Cards:- (Stacked in spanwise direction) CARD ii

Locanion of origin of section input points

Scaling factor and rotation angles

Type of section input

Nodes to signal changes in spanwise panel

distribution, surface curvature, end of

patch, etc.

NPS Number of spanwise panels in the interval

INTS Way in which spanwise section is divided

Defininu Input Points:- _. v

BX, BY, BZ Coordinates of section points.

on INMODE used.

Form depends

11
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Chordwise Nodes:- CARD 14

NODEC Nodes to signal changes in chordwise distribution, surface curvature, end of section,

etc.

NPC Number of chordwise panels to be generated in

in the interval

INTC Way in which chordwise section is to be

divided

The values of the nodes used to delineate changes in either

chordwise (NODEC) or spanwise (NODES) directions are the same.

In both cases, values of 1 and 2 represent the end of a region

within a patch where in the first case, surface curvature is

continuous into the next region and in the secondcase is discontinuous. A value of 3 indicates the end of a section, chordwise,

or a patch, spanwise, while values of 4 and 5, used only on the

last sections of patches indicate, respectively, the final sections of components and of the whole configuration.

A similar arrangement with matching values is used to indicate the way in which the surface is to be divided in the

chordwise and spanwise directions. The parameters, INTC and

INTS: may be values of 0 through 3 depending on whether the

points are to be:

value

Closely spaced at the beginning and end of the region 0

Closely spaced at the beginning of the region 1

Closely spaced at the end of the region 2

Equally spaced 3

When an unequal dis=ribution is called for, the distance

along the surface across the interval is bzoken up using a cosine

form. A detailed description of the procedure is given in the

Program VSAERO Manual, Ref. i.

Of course, the panelling could be built directly upon the

input points and sections with no subdivision or interpolation.

In this case, the input points on successive sections are simply

connected together to form the panelling. This option is selectable by setting NPS or NPC equal to zero. Any values other than

zero determine the number of panels within the particular spanwise or chordwise interval.

12
In the discussion above, the standard method of inputting

configurations has been outlined. Program VSAERO offers many

other options. Two of them, which are particularly useful in

entering helicopter shapes, are outlined below.

3.1.2 Bodies of Revolution

There are many applications in the modelling of typical

helicopter sha_es that do not require the detail provided by

section by sectlon input. Man_ configuration elements, in fact,

may be simply defined as bod%es of revolution. Examples aEe

engine nacelles, tail boom sections, rotor head fairings and

external stores. Figures 5 and 6 illustrate how two of these, a

simple engine nacelle and a rotor head fairing (or radome) may be

generated.

For the first example, Figure 5, the engine nacelle, the

unit is made up of one section defined in the y - 0 plane by

inputting values of x and z to outline the profile and then

rotated through 3600 to form the nacelle. It can be modelled as

one patch with four separate regions. They are: the inlet face,

the inner surface of the inlet, the outside surface of the nacelle, and, finally, the exhaust plane.

As with normal input, the card set describing the nacelle is

preceded by a patch card. Generally, only one section card is

required. This locates the input section in the global coordinate system and specifies its orientation and scale relative to

that frame. The parameter, INMODE, describes how the section

points are to be input; INMODE=2, for both the examples in

Figures 5 and 6 signifies points being entered in the y - 0

plane. If a flow-through nacelle _ere being modelled, INMODE=5

could have been used to specify a standard NACA 4-digit cross

section.

The body of rotation option is selected by setting the

spanwise node card, NODES, to a negative value. For the examples, simple polar symmetric bodies are used so NODES is -3 in

both cases. However, more complex bodies may be built up by

combining sections to vary panel density, and in that case,

values of -i o_ -2 would be appropriate at the intermediate

spanwise sections depending on whether the surface curvature was

continuous or discontinuous across the node. The final section,

completing the rotation, would, of course, have NODES--3 signifying the closing of the patch (or -4 or -5 if this were the last

patch on the component on the body).

Definition of the cross-section points (defining the local

chordal shape) follows the same rules for defining conventional

cross sections outlined above.

13

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The input set is completed by specifying the final and

initial angles, _,to define the rotation arc on CARD 15. For a

body such as the nacelle, remote from the system plane of symmetry, a full 3600 of rotation is used. However, in the same

applications where the flow is symmetrical, where no yawing is

involved and where the body is on the plane of symmetry, then

only the positive side of the body of revolution is defined and

is 180o.

The second example used, the ellipsoidal fairing of Figure

6, illustrates another feature of Program VSAERO; that is, the

ability to construct elements of the configuration as separate

components in the most convenient orientation and then rotate

them or move them to the required location. The positioning an@

rotation a_e controlled by entries on a special component card

which must precede a patch or a group of patches identified as

belonging to a separate component. This card precedes the first

patch identifying card.

In the simple example given the component is made up of only

one patch. As with the nacelle, it is defined in the y - 0 plane

by inputting the values of x and z outlining the cross section.

This outline is then rotated about the section 'X' axis to form

the body of revolution.

Once the shape is formed in the section coordinate system,

three further processes are available at the component level

before the final shape is set in the global frame. At this

level, all the patches within the component may be scaled, either

increased or reduced in size, rotated or translated. The changes

are applied in that order. Two rotations are available; a simple

one, where the body is rotated about the component 'Y' axis and

rotation about a general axis that is deflned by two input

points. The simple rotation is the d_fault mode. The userdefined axis rotation is entered by specifying a negative value

for the scale parameter and then inserting an extra data card

which contains the rotation axis defining points. For the simple

fairing case shown in Figure 6 the default is used and the body

is pitched up 900 to lie with its long axis in the horizontal

plane.

3.1. _ Liftina Surfaces--Type-3 Patches

A further option offered by Program VSAERO which is

useful in modelling components remote from a region of interest

is the ability to use a _ifting-surface representation rather

than a full surface singularity model, and enforcing the N_umann

rather than the Dirichlet boundary condition. A typical application of this feature would be in modelling wings or other lifting

or control surfaces that do not have a direct effect on the components that were the focus of the study or in regions where no

18
B

{

aerodynamic rigor is sacrificed by not including the effects of

the thickness of the components. Figure 7 shows examples of this

where simple type-3 patches are used to model typical

vertical/horizontal tail assemblies.

Depending on the level of detail required, this assembly

could be created by as few as two defining points on each of

three sections if simple, flat surfaces are desired. The example

in Figure 7(a) and (b) shows this input. The group of input

cards required is preceded by a patch card (and a component card

if a separate component is called for) callin_ out a type-3

patch. Input continues with the section card defining the lower

root and then two cards defining the trailing- and leading-edge

points followed by a chordwise node card. Note that on the

chordwise node card the program is instructed to break the chord

down into five panels, NPC-5, distributed so that they are denser

at the leading edge, INTC-2.

The second section card, at the joint between vertical and

horizontal planes, with a spanwise node value, NODES, of two

signifying a discontinuity in surface curvature, Contains the

information to divide the vertical section in the spanwise direction into four rows of panels, NPS-4, spaced equally,

INTSm3. Input is complete with the section defining the horizonual plane. In this case there are five panels spanwise, NPS-5,

divided so that they are spaced densely at root and tip, INTS-0.

Since this is the last section to be input on this patch, the

spanwise node, NODES is set equal to three. The panelling in the

chordwise direction is the same on the horizontal plane as in the

vertical.

In the second example, Figure 7(c) and (d), cambered sections are used on both the vertical and horizontal sections and,

consequently, a small transition piece is required to go from the

vertical to horizontal planes. This is formed quite simply by

allowing the program to correct th_ sections defining the top of

the vertical panel and the root of the horizontal panel and

generate a row of panels to fill the gap. To do this, four

sections are required, The first section, as before, defines the

root of the vertical panel this time using INMODE-I, points input

as X and Y values, to define the section camber line. The section was defined relative to the quarter chord point; th_ values

of STX, STY, and STZ locate the section in the global frame. In

the example, the camber line distribution is assumed constant up

the panel and as a consequence, the top section is input by

simply relocating the root section with the appropriate values of

INMODE-0, with the SCALE factor set to give the correct taper.

The root section of the horizontal plane is again defined

with input points, this time values of X and Z in a constant Y

plane, INMODE-2, taking care to place it in the correct position

relative to the earlier input sections using the appropriate STX,

STY, and STZ local origin values. Again the tip section (the

camber is assumed constant) is input simply by copying and

19
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scaling the root section. He_e, however, the section is pitched

down using the pitch angle control, ALF, to model an appropriate

value of section twist. Since both surfaces and the connecting

fairing are being modelled as one patch, the chordwise distribution of subdivided panels must be conserved. This does not

require, as in this example, that the same number of points be

input provided that the chordwise node cards for each section

have a non-zero value for NPC, the numbez of panels chordwise,

and that this is repeated at each spanwise station.

3.1.4 Rotors--Type-4 Patches

In the body/rotor analysis, two models of the rotor are

constructed. They are the detailed blade element model which is

to be discussed later and the panel model which provides the

coupling between the rotor and fuselage flow fields. The panel

model of the rotor is constructed in much the same way as the

bodies of rotation discussed above with the added fact that the

chordwise and spanwise (in the rotor framework radial and azimuthal) panel breakdown forms the basis for the radial spacing of

blade stations and the azimuthal increments in the blade element

calculation.

The rotor is modelled using a disc-like array of panels

generated in exactly the same way as the bodies of revolution.

The panels are represented, as are all panels in program VSAERO,

by a combination of source and doublet singularities. In a type4 patch both source and doublet elements of the singularity are

specified (known as a result of the blade element calculation)

and are passed over, within the program, from the blade element

to the panel calculation. Part I of this reporu contains an explanation of the form of the singularities. Each rotor disc must

form a separate patch preceded by the appropriate parch card and

it is recommended that they also be identified as a separate

component for ease of manipulation and the separate accumulation

of loads. Figure 8(a) and (b) shows how a typical main rotor may

be generated.

The input for this example, Figure 8(b), begins with a patch

card with IDENT set to four (4) to signify a rotor. This is

followed by the section card, placing the rotor center in th_

global frame with the appropriate values of STX, STY and STZ and

announcing that a body of revolution is to be generated with

?_ODES--3, -4 or -5. Using this approach, INMODE is most commonly

two (2) and the line defining the rotor disc is input in the y -

0_0 plane with values of x and z and rotated about the x-axis

(default). It is at this stage that blade coning can be introduced., as in the example. With this simple form only two points

are required, but, of course, any higher-order description may be

used to generate curved rotor disc surfaces. In the example, the

point closest to the axis forms the innermost defining station

for the aerodynamic parts of the blade and the outer point the

tip radius. Normally the blade radius is broken down

24

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automatically specifying, as in the example, the inner and outer

points and the number and distribution of panels to be formed on

the chordwise (radial) node card. INTC-2 is recommended for the

radial breakdown since this concentrates the panels at the outer

end of the radius. The number of panels is dictated by the

detail required. Cases have been successfully executed with as

few and 3 panels radially and the maximum set by program capacity

is 20. Experience with conventional rotor performance programs

has shown that fifteen segments radially is more than adequate

for detailed blade studies.

Since the disc is being formed by the body of revolution

feature, the number of azimuth stations is set by the NPS parameter on the section card and the distribution should be uniform with INTS set equal to three (3). The input is completed by

including the rotation angle range of 3600.

With the disc panelled in the input location about the xaxis, all that remains is to pitch it into the appropriate atti--

rude. This is accomplished using the rotations available on the

component card. The default rotation is about the component yaxis with a positive rotation being nose-up. In the example, it

was determined that the tip path plane should be 50 nose-down so

the rotation required on the component card to place the disc in

the correction orientation was +850. The values of the component

origin, CTX, etc. then locate the rotor relative to the rest of

the configuration

If a more involved rotation was required, say to apply some

lateral tilt to a main rotor or to position a tail rotor, thls

can be done by activating the option to specify the axis of

rotation. This is done by setting the scale parameter on the

component card to a negative value and inserting on the following

card two points specifying the rotation axis. The details for

applying this technique are discussed in full in the VSAERO

program guide and are summarised in Figure 9(a) and (b) for the

case of a tail rotor. Here, as a further example of the program

flexibility, the rotor is input with unit radius and the scale

parameter on the component card is used to bring the radius up to

the full scale value. A further point to note in the tail rotor

model is that the rotation angle range has been changed to: 02 .

450.0__ = 90.0. This is required to line up the first panel in

the pane_ model of the rotor with the zero azimuth location in

the blade element model. Since this is conventionally over the

tall for the main rotor and along the aft pointing horizcntal

radial for a tail rotor, the tall rotor panel model before rotation must start in the horizontal position. The same effect

could, of course, be achieved by using INMODE-3 or 4, carrying

out the original line definition in the z - 0 plane and by

returning to the %2 " 360.0, 81 " 0.0 degrees rotation range.
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I
4.0 WAKE INPUT

4.1 Wake Gri_ Planes:- CARD SETS 17 and 18

In program VSAERO the development of the wakes after they

are shed is calculated in a series of planes perpendicular to the

onset flow starting upstream of the first shedding location. The

way in which these planes are set up is described in full in the

VSAERO program guide and the recommendations made there fOE fixed

wing aircraft and general shapes apply equally well to rotor/body

problems.

Figure 10(a) illustrates how the defining grid planes would

be set up for a typical helicopter study. Note that the first

grid plane corresponds to the leading edge of the disc. As a

eneral guide for isolated rotors, the grid planes should be

istributed over the disc to correspond to the azimuthal breakdown of panels using a full cosine distribution (dense at

leading- and trailing-edges, open in the center) with steps equal

to half of the total rotor azimuthal increments. Downstream of

the trailing edge of the disc, the first two disc diameters of

distance could be broken into ten segments with half cosine

spacing and then a further six diameters with four large segments

to fill in the fan-field effects.

In regions _here substantial flow distortion is expected,

say around the front of a fuselage or if details of the passage

of a wake over a wing leading edge are required, then regions of

more closely set grid planes are required. Figure 10(b) is an

example of how this may be achieved.

As with the input of body sections, the wake stations are

specified by inputting a series of values separated with node

cards which indicate how intervals are to be divided up. The

number of divisions may be specified using NPC; the distribution

is specified as with body input using the parameter, iNTC, and as

before, individual stations may be input and used without further

subdivision by setting NPC equal to zero. The last wake grid

plane should be followed by a node card with NODE set equal to

three (3) to terminate wake grid plane input.

4.2 Separation Line Specification:- CARD SETS 19 _ 23

In the version of program VSAERO described in this report,

two types of wake are available. These are the type-I wakes,

springing from lifting bodies, and the type-4 wakes, enclosing

regions of flow with energy states higher or lower than the

surroundings. The way in which these wakes are described are

generally similar, the attachment process is identical and they

only differ in that for the type-4 wakes the velocity jump across

the jet sheet must be identified in order that the p_ogram may

assign the correct vortex strength to the sheet elements.

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While the uses of the type-i wakes are clear cut, on wing

and other lifting-surface trailing edges, the use of type-4 wakes

requires some additional explanation for the helicopter application. Several elements of helicopter configurations shed wakes

where changes in energy level are involved. Most obvious is the

efflux from the powerplant. Less clear, but nonetheless important, is the wake from the rotor head assembly. Since, in this

case, the shape is normally not modelled in detail and the drag

coefficient of the assembly is generally known, it is possible to

model the overall effect of the component by constructing a bulk

model and attaching a type-4 wake along its aft facing edges.

The rotor model also uses a type-4 wake.

Each individually identified wake is treated in much the

same way as a patch is handled in the body input and, as in the

case of the patch, it must be preceded hy a wake (patch) card,

CARD 19. This card contains the information which identifies the

wake type, IDENTW-I for a regular wake or -4 for a jet

model/separated base/roto: wake; indicates whether the wake is

held fixed or is relaxed, IFLEXW-I or 0, respectively; and a

descriptive title.

4.2.1 Wake Definition for TvDe-i Wakes

The method of attaching the wake along the separation line

is explained in detail in the VSAERO Program User's Guide. The

following notes should be considered a supplement to the original, more detailed presentation.

The separation line is applied to the surface in such a way

that the local attached flow comes from the left. In the example

shown in Figure ii the separation is parallel to side 2 of the

patch. The string of panels to which the wake sheet is attached

is identified on Card 20 as follows.

(KWPACH) (KWSIDE) (KWLINE) (KWPANI) (KWPAN2) (INPUT) (NODEWS)

1 2 0 1 6 2 0

(or 0) (or 0)

Default for the set

of panels alongside

KW._IDE

Dsing the default, 0, for

KWPANI, KWPAN2 in cases

where the string of panela

is the complete set parallel

to side KWSIDE is recommended

KWPACH is the patch to which the wake is attached and KWSIDE the

patch side parallel to and in the same direction as the shedding

line. If the sheet is attached along the patch edge, KWLINE

takes the default value of zero. However, if the sheet were

attached along an internal panel edge, this would be identified

by counting, in this case along side 1, until the shedding panel

33
ORI_INAI_ PAQE I1i

OE POORQUAU'I_

S DE /./

(FIRST SECTION INPUTT_

3

FLOW

DIRECTION

SIDE 1

SEPARATION LINE

WAKE LINE 1

INPUT WAKE LINES

WAKE-SHEDDING PANELS

(TO THE LEFT OF THE SEPARATION

LINE)

"-- WAKE LINE 2

PROGRAM

GENERATES

IMMEDIATE LINES

BY LINEAR

INTERPOLATION

"I Figure ii. Type-i Wake-Wing Separation Lines.

34
was _eached. This number, then, defines KWLINE. KWPANI and 2

define the spanwise extent of the shedding; again the default

values of zero give full span, and numbering proceeds across the

patch in the direction of the shedding line where only part-span

shedding is present. Card 20 is equivalent to the section card,

Card Ii, of the body input.

Because INPUT is 2 on card 20 above, this card must be

followed by CARD SET 21/22 defining the _eometry of streamwise

wake-line, LINE i. As with the input of body section data, the

wakes may be prescribed in a number of ways. For the current

example, INPUT-2 indicates that the program expects data to be

entered in X and Z coordinates with a local origin at the shedding point. As with the body input, wake filaments may be described with any level of detail desired and the wake segmented

with node cards separating the different elements. For the

simple case used here, if an initially rectilinear wake was

required, it should be enough to prescribe a point in the far

field downstream and a node card. If the wake had to pass an

obstruction, say another body or a flap, a more detailed path may

be prescribed. Both examples are outlined in Figure 12 below.

In both cases the X and Z coordinates are relative to an origin

at the trailing edge. CARD SET 21/22 is equivalent to CARD SET

12/14 of the body input.

When the input is complete the wake is terminated with

another CARD 20:

(INPUT) (NODEWS)

0 0 0 0 0 0 3

The string of wake-shedding panels

has already been defined

This copies LINE 1 to LINE 2 to

complete the wake geometry description. (Note that INPUT>0

can be used here if a differen_

wake line geometry is required,

in which case CARD SET 21/22 must

follow foc LINE 2)

End of this wake

but another wake

must follow. The

final wake

have a 5 here

Note: In the case of type-i wakes (IDENTWsl on CARD 19) it is

possible to turn the wake over and attach it along side 4 of the

patch--in this case it would start at the tip and move inboard.

CARD 20 would then be:

35
ORIGINAI_ PA_3_ I_

OE POOR QLIAUTY

SIMPLE WAKE

LAST WAKE GRID PLANE

o

INPUT POINT

.uu,. :? _f2,:,,2,9

SWPZ A

MORE COMPLEX WAKE

REGION 2

WAKE 1 I

WAKE 2 -'-"

• INPLFI_ POINTS

(H:.',='" "-:J@ Z

_-00 f'" [O0 CC:

].ZO:': .C" " .-'O :'_'

[,_O0 CO _:OO C:_'

-_20'."<O -_':'O ,D,.:

'.:22,61..: :'=C :._.C

REGION 1

REGION 2

(WAKE 2 NOT SHOWN FOR CLARITY)

Figure 12. Wake Trajectory Definition.

36

)
(KWPACH) (KWSIDE) (KWLINE)

1 4 0

ORIGINAL PAGE I$

oF. POOR QUALII_

(KWPANI) (KWPAN2) (INPUT) (NODEWS)

1 7 2 0

(or 0) (or 0)

No change

In the initial example, the wake input at the first section was

simply copied across the span, but in many cases this would be

inappropriate. A more involved example is given below.

Changing the wake line geomtry in the middle of a patch is

achieved by simply breaking the string of wake shedding panels

into sets. This is possible since there is an opportunity to

define a streamwise wake line at the beginning of each string of

wake-shedding panels and at the end of the last string• This is

explained by Figure 13. The input for these wakes would be as

follows

IDENTW

CARD 19 1 0 0 Wing Wake

CARD 20 1 2 0 1 5 2 0

CARD SET 21/22

for Line 1

CARD 20

CARD 20

SWPX(1) , SWPZ (i)

SPWX(2), SWPZ(2)

1 2 0

INPUT=2 Format

(NODEWS) (NWP) (INTC)

3 I0 3

6 6

KWPANI, KWPAN2

1 2 0 7 12

0 0

INPUT -0

Copies Line 1

into Line 2

2

INPUT for

Line 3

37
ORIGINAEPAGiE15

OE POOR QUALITY

al

I I

I I

I

,I

@®

TOP VIEW

7

!

' i I ,

I ' i

--" 'l i -_ LOCAL-

, ._-8 9 i 10 i]] i.'l_ SEQUENCEOF

I PANELS COUNTED

ALONG

I SEPA_TION

I LINE

I

I

I STREAMWI SE

WAKE LINES

(_ DEFINED INPUT IN

C

SIDE VIEW

1

__ __._-- ----"-- LINE (_

-'_'_"___ -- 3 LINE (_

• INPUT POINTS _'- _ _ LINES (_) AND 2@

3 " LINES (_ AND @

(SECOND WAKE)

Figure 13. Wake Shedding Schematic--Multi-line Input.

38
CARD SET 21/22

For Line 3

CARD 20

SWPX (i) , SWPZ (i)

SWPX(2), SWPZ(2?

(NODEWC) (NWP) (INTC)

3 i0 3

0 0 0 0 0 2 3

NODEWSs3

terminates

this wake

_t

.j

I

CARD SET 21/22

for Line 4

CARD 19

CARD 20

CARD SET 21/22

for Line 5

SWPX (i) , SWPZ (i)

SWPX(2), SWPZ(2)

e •

1 0

2 2

SWPX(1), SWPZ(1)

SWPX(2), SWPZ(2)

(NODEWC) (NWP) (INTC)

3 i0 3

0 Flap Wake

0 0 0 2 0

(NODEWC) (NWP) (INTC)

3 10 3

CARD 2 0 0 0 0 0 0

INPUT-0 Copies Line

5 (i.e., the previous

line) into Line 6

0

NODEWSs5

for final

wake

5

!

P

i

If the wake separation line passes over a number of patches then

a separate string of wake-shedding panels must be specified for

each patch. (Multiple strings of wake-shedding panels may still

be specified within a patch as shown above)• This is illustrated

3g
with the example shown in Figure 14. Following the sketch, the

multipatch input for this wake becomes:

KWPACH K'_SIDE KWLINE KWPANI KWPAN2 INPUT NODEWS

CARD 20 1 2 0 0 0 2 0

CARD SET 21/22 FOR WAKE LINE 1

CARD 20 2 2 0

CARD 20 3 1 0

0 0 0 0

(Copies wake line 1 into

wake line 2)

5 6 2 0

CARD SET 21/22 FOR WAKE LINE 3

CARD 20 3 2 0 0 0 2 0

CARD SET 21/22 FOR WAKE LINE 4

CARD 20 0 0 0 0 0 2 5

End of Wake Input

CARD SET 21/22 FOR WAKE LINE 5

_ARNING: Before leaving the discussion of type-i wakes, it is

important to note that the panelling on the upper and lower sides

of the wake mus_ match. This is required so that the correct

doublet jump across the wake may be properly evaluated and shed

into the wake columns.

4O

L

_ __.;_ xj
PATCH 2

OmC,_IAI: PA(W !_

OF.POOR _UALITY

PATCH 1

PATCH 3

SIDE i

!

/

I

i

I

I

0

WAKE LINES

SIDE 2

SIDE 2

SIDE 3

I

I

I

®

Figure 14. Multiple Patch Wakes.

41
4.2.2 Wake Definition for Type-4 Wakes on Bodies

Type-4 wakes are specified in the same manner as type-i

wakes, and are fed by flow from the left when looking along the

direction of the separation line. Figure 15 shows two examples

of this type of wake.

In the jet efflux case, Figure 15(a), the nacelle and base

are all part of the same patch and the wake is attached along the

aft-facing edge. This is parallel to side 2 of the patch on the

17th row of panels along side 1 (see Figure 5 for details of

nacelle panelling). Consequently, KWPATCH takes the nacelle

patch number, KWSIDE-2 and KWLINE-17. Since the wake is attached

across the full width of the patch, KWPAN1 and KWPAN2 are set to

zero,

In the case of the rotor head block model, Figure 15(b), the

block is in three parts with separate patches for the front and

rear faces, patches 1 and 3, and the main surface as patch 2.

Here, the wake is attached along the edge, side 3, of patch 2.

Consequently, KWSIDE-3, KWLINE-0 (the default for the edge) and

KWPANI and KWPAN2 are again zero, since the wake goes all around

the edge of the patch.

The wake geometry for type-4 wakes is defined in a manner

identical to that required for type-i patches on CARD SETS 21/22.

Since type-4 patches involve regions of higher or lower

energy and the wake strength is set to produce the appropriate

internal flow, the inner and outer velocities (normalized with

respect to a unit onset flow) must be specified. This is done on

CARD SET 23 immediately following the wake definition.

Input for normal type-4 wakes (i.e., those attached to

normal wing or body patches) is completed by ensuring that the

flow into the wake cavity, from the area of panels enclosed by

the wake, matches the flow down the inside of the wake column.

This is done by using the option available within the program to

suspend the usual assumption of zero flow through the boundary

and by replacing it with appropriate normal velocity. This would

be positive for an outflow. The special options available with

CARD SET 8 provide this capability.

The first entry on Card 8, NORSET, sets the number of

regions in which the transpiration velocity is to be changed. If

this is non-zero, the program then expects to read a Card 8A for

each region. Explained in detail in the VSAERO manual, Card 8A,

identifies the patch and the rows and columns involved, and

specifies the lelocity value. Examples are given of typical CARD

SET 8/8A input for the two cases in Figure 15.

42
• \

ORIGIINAL PAGE li

OF,POOR QUALITY

PANEL NUMBERS

COUNI_ ALONG

SIDE 1

_S IDE 1

NACELLE BASE

PARALLEL TO SIDE 2

SEPARATION

PANELS TO LEFT

OF SEPARATION LINE

KWSIDE=2; KWLINE=17

KWPAN1 AND KWPAN2 = 0

CARD 8

(NORSET NVORT NPSOM JETPAN)

1 0 0 0

CARD 8A

(NORPCH NORF NORL

1 18 i

NOCF NOCL VNORM)

0 0 2.5

DEFAULT FULL WIDTH (TYPICAL)

Figure 15(a) . Type-4 Wake on Nacelle.

43
PAQE I_

OE POOR QUALITY

F; 3

FLOW

KWPATCH=)

KWSIDE:5 __

_LI NE=O _._..

kSVPAN1AND _PAN2 = 0 "

CARD 8:

(I_ORSET NVORT ETC.)

1 0

CARD 8A:

(NORPCH

3

Figure 15(b).

NORF

0

NORL NOCF NOCL VNORM)

0 0 0 0,0

DEFAULT FULL PATCH TYPICAL

Type-4 Separated Wake on Block Model of Rotor Head.

44
CARD SET 8/8A is also used to identify sets of panels which

are known to fall inside £egions of higher/lower energy level.

This is required if correction of the calculated values of the

pressure coefficients to account for the altered dynamic head of

the region is desired. As with the outflow option above, the

number of sets of panels to be modified are identified with

JETPAN on CARD 8 and the patch row and column information supplied on CARD 8A for each set. The incremental dynamic head is

calculated with the wake sheet values of VIN and VOUT input on

CARD 23.

4.2.3 Wake Definition for Type-4 W_';_

The wakes used in the rotor calculation are a special

form of the type-4 wakes discussed above and are invoked by the

program automatically when a type-4 wake is attached to a type-4

rotor patch. Wake attachment is similar to that described for

other type-4 patches above, but extra care must be taken to

completely enclose the wake volume. This is detailed in Figure

16.

Considering how the rotor patch is generated by rotating the

input section, the chordwise (in this case radial) direction is

side 1 of the _atch. The outer edge of the disc becomes the

spanwise directlon and is side 2 of the patch. Side 3 and side 4

follow naturally to complete the definition. The card set for

the wake is as follows.

(IDENTW) (IFLEXW) (IDEFW) (WNAME)

CARD 19 4 0 0 ROTOR WAKE TIP

Type-4 Wake

Distorted wake

will be calculated

Separation line

definedby panel

string, Card 20

must follow

CARD 20

(KWPATCH)(KWSIDE) (KWLINE) (KWPANI)(KWPAN2) (INPUT) (NODE}'G)

1 2 0 0 0 2 0

Tip circle Default

attaches Default attaches

wake along wake along the

patch edge full length of edge

45
ORIGINAK PAGE. I_

OF, I_OOR QUALITY .- .-

TIP ___ SIDE 2 .. .- /'

_ '"\ ii I _CONNECTING SHEET

ROOT SEPARATION

PANELS

£,

Figure 16. Rotor Wake Specification--Simple Isolated Rotor.

46

)
CARD SET 21/22: DEFINING WAKE FILAMENT AS IN TYPE-I WAKES ABOVE.

CARD 20

(KWPATCH)(KWSIDE)(KWLINE) (KWPAN1) (KWPAN2)(INPUT) (NODEWS)

0 0 0 0 0 0 3

terminates

copies filament input tip wake

on previous CARD 20 to

close wake column

(IDENTW IFLEXW IDEFW) (WNP_E)

CARD 19 4 0 0 Rotor Wake Root

CARD 20

(KWPATCH) (KWSIDE) (KWLINE) (KWPANI) (KWPAN2) (INPUT) (NODEWS)

1 4 0 0 0 2 0

CARD SET 21/22: TO DEFINE WAKE LINES

CARD 20

(KWPATCH) (KWSIDE) (KWLiNE) (KWPAN1) (KWPAN2) (INPUT) (NODEWS)

0 0 0 0 0 0 3

Terminates root

vortex

(ID ENTW IFLEXW IDE FW) (WNA ME )

CARD 19 1 0 0 Connecting Sheet

CARD 20

Note type-i wake

for connecting sheet

(KWPATCH) (KWSIDE) (KWLINE) (KWPANI) (KWPAN2) (INPUT) (NODEWS)

1 3 0 0 0 2 0

CARD SET 21/22: TO DEFINE WAKE LINES

CARD 20

(KWPATCH) (KWSIDE) (KWLINE)(KWPAN1) (KWPAN2)(INPUT)(NODEWS)

0 0 0 0 0 0 5

Last Wake

Input

47
This example shows the simplest form of rotor wake input and

provides an initially prescribed skewed cylinder form for the

wake tube generated by copying the first filament input around

the edges of the patch. This is adequate for cases where no body

is in close proximity to the rotor. For cases where the fuselage

presents substantial interference, a more involved wake

specification is required. An example of this is provided in

Figure 17 and below. The technique is identical to that

illustrated above for type-i wakes varying in a spanwise

direction. For the example, the rotor disc has been divided into

16 azimuthal sections (columns). Although the analysis in

program VSAERO can cope with an initially prescribed wake

filament passing through a body, it is better from the point of

view of numerical stability if all filaments are prescribed so

as to pass over the outside. In the situation pictured in

Figure 17, the fuselage is narrow relative to the disc panelling

and only the three filaments from the front of the disc, from

columns 8, 9 and I0, need to be bent to pass around the body. In

the illustration, filament 1 is copied around the edge to filament 7. Filaments 8, 9 and i0 are input individually. Filament

ii is a return to the original trajectory and this is copied

around until the wake closes at filament 17. The data set for

this looks as follows. It should be noted that the filament is

associated with the trailing corner of the panel in questions

(corner 2 in the example shown).

(KWPATCH) (KWSIDE) (KWLINE) (KWPANI) (KWPAN2) (INPUT) (NODEWS)

CARD SET 20 1 2 0 1 6 2 0

Attachment to Input as

columns 1-6 X and Z

CARD SET 21/22: WAKE FILAMENT INPUT AS X AND Z RELATIVE TO SHEDDING POINT FOR FILAMENTS 1 TO 6 AND TO BE COPIED

TO 7.

CARD SET 20 1 2 0 7 7 0 0

Last section of Copies

"constant" wake previous

section

CARD SET 20 1

CARD SET 21/22:

2 0 8 8 2,3 or 4 0

Filament 8 Input as

required

WAKE FILAMENT INPUT AS X,Z OR X,Y OR X,Z AS

NEEDED FOR FILAMENT 8.

48
ORIG_iAL PA(m

oF. POORQu,_.r_

TIP-EDGE

P&

LINE 8

LINE 9

LINE i DEFINED :

FUSELAGE

INPUT WAKE LINES

COPIED WAKE LINES

NOTE: FOLLOW SAME PROCEDURE

FOR ROOT WAKE LINES,

LINE 17 (CLOSE 16)

COPIED

\

-k

_ - SIDE 2

___ S._Ew PAA__K_A____II ON_L IDE

SIDE 1

TYPICAL TIP-EDGE

SHEDDING PANEL

Figure 17. Rotor Wake Input Schematic with Fuselage Present.

49

)
CARD SET 29 1

CARD SET 21/22:

2 0

FOR FILAMENT 9

9 9 2,3 or 4 0

CARD SET 20 1

CARD SET 21/22:

2 0

FOR FILAMENT i0.

i0 I0 2,3 or 4 0

CARD SET 20 1

CARD SET 21/22:

CARD S ET 2 0 0

2 0 Ii 16

FOR FILAMENTS ii THROUGH 16.

MENTS 1 THROUGH 7.

0 0 0 0

2 0

SHOULD MATCH FILA0 0

Copies 16 to 17

and closes outside

of wake

Wake definition continues with the input along sides 3 and 4

of the patch displacing the wake filament as appropriate to pass

around obstructions.

Since rotor wakes are type-4 wakes, the initial wake

strength must be defined with CARD SET 23, specifying VINNE R and

" This is updated internally as the calculation proceeds.

IKe conventional type-4 wake situations, there is no need to

use NORVEL (on CARD 8) for rotor patches since the disc panel

boundary conditions are set internally using local loadings supplied by the rotor blade element calculation.

In a conventional VSAERO data deck, the wake data completes

the Input string required for the aerodynamics calculation.

However, if any type-4 rotor patches have been called, the

program expects to read the input data set for the rotor blade

elmement calculation. This is described in the next section.

L t

5O

!

._--p. ,,.-_ ,,. .... -
5.0 ROTOR BLADE ELEMENT MODEL INPUT DESCRIPTION

When the presence of a rotor is signalled by the insertion

of a type-4 patch, the program requires that the data be loaded

to construct the blade element model. This data set identifies

the body patch involved; contains the controls which limit print

volume and iteration cycles; pzovides the description of the

blade geometry and mass properties including twist, planform and

airfoil section; and defines the flight conditions.

5.1 Rotor Patch Identifiers (Cards R1 and R2)

Since the blade element model is built on the framework

provided by the panel model, with disc panels and blade segments

being matched, the first data items identify the rotor patch.

CA[D SET R1 provides the patch number and orients the disc for

the blade element velocity components. The parameter roll is the

relative angle of rotor, zero degrees for a main rotor and ninety

degrees for a tail rotor. The roll angle is used simply to

resolve the induced velocity components generated in the body

axis system into the correct relation for the blade element

analysis. Card R2 provides a general title for the rotor calculation.

5.2 Output Print Controls (Card R3)

As an aid in rotor performance diagnosis, different levels

of printout are available. At the most detailed level, all of

the blade section geometric onset flow and loading data are

available at each radial and azimuthal station for every step in

the iteration cycle. This includes in the first group, available at every radius and azimuth:

blade section radius, span, chord, geometric pitch, angle of

attack, yaw angle, inflow angle, Mach number, velocity

components in rotor control axis system, induced velocity

components in body axis system, section lift coefficient,

and section drag coefficient.

The second group includes the loading data available every radius

and azimuth. These are:

blade loading (lift/unit span), H-force loading, total

torque loading, drag torque loading, lift torque loading,

segment lift, segment H-force, segment total torque, lift

torque, and drag torque.

The third group includes integrated blade data available at

each azimuth location. This is made up of principally blade

lift, H-force and torques and includes the blade flapping

parameters, the flapping angle and the first and second flapping

derivatives.

51
Rotor totals are printed for each iteration and are not

selectable.

The output data selection is completed with an option to

print the airfoil data as input and as interpolated at intermediate stations. It is recommended that restraint be exercised

in switching on the print options since large volumes of output

are generated. Irrespective of the print option chosen, the plot

file contains all of the data for the final iteration cycle. The

printout default values are all OFF &nd a particular group of

output must be selected by inputting a value of one for the

parameter. Card R3 is arranged in columns of i0 as outlined

below.

I S PNTI IS PNT2 IB PNTI IPT1 IPT2

Card 3 0 or 1 0 or 1 0 or 1 0 or 1 0 or 1

Group 1 Group 2 Group 3 Airfoil Data

Blade section data

at every radius and

azimuth

Blade totals

at each

azimuth

5.3 Iteration Controls. (Card R4)

The rotor model used in the delivered verison of the program

is for a fully articulated rotor and the performance calculation

may proceed in either of two modes. In the first, direct mode,

the blade control angles are preset and the calculation goes one

cycle. In the second mode the rotor forces and moments are

requested and the controls adjusted through three embedded iteration loops to produce the desired levels. The parameters entered

on Card R4 control this process. These parameters, with MCOUNT

controlling rotor moments, LCOUNT controlling rotor lift, and

NFLAP controlling blade flapping, and hence control axis orientation, may be set individually or together using default values.

5.3.1 Blade FIaDDinu

The innermost iteration is the blade flapping cycle

which steps the blade around the azimuth calculating the loads

based on t_e local conditions and the blade response to conditions at the previous step. The blade is assumed to be fully

articulated. The default value of the controlling _rameter is 4

(four full azimuthal cycles allowed to stabilize apping). If

the blade flapping cycle is inhibited, by setting NFLAP-I the

blade flapping parameters, the control axis angle and the fore,

aft and lateral flapping inputs must be included on Card RII.

Even if the default flapping cycle is selected, NFLAP-0 (set to 4

52

t
internally), it speeds convergence if values of control and

flapping angles are set on Card RII.

5.3.2

The rotor lift is modulated using the collective pitch

control. A total of six iterations are permitted if the default,

LCOUNT-0 (set to 6 internally) are used. A starting value of

collective pitch must be entered on CARd RII. The search for a

converged value of collective pitch uses a quadratic fit through

the successively updated calculated thrust values, comparing at

each step with the target value. Blade flapping equilibrium is

re-established after each change in collective pitch.

5.3.3 Rotor Moments

The rotor pitching and rolling moment loop entered on

Card R4 produces the default, three iterations. If a search is

ordered, target values of pitching and rolling moment must be

loaded on Card RI3 or zeroes will be assumed. If MCOUNT is set

equal to I, values of lateral and fore and aft cyclic pitch must

be input on Card RI2.

5.4 _ Element Model Geometry (CARD SETS R6, R7, R8,

Rg, R10)

In the program the basis for the blade geometry and breakdown into radial sections comes from the panel model. Having

identified the appropriate patch, the panel corner points on the

first column of the patch are studied (by the program). At the

same time the number of rows (bla_e segments) is set, NR, and the

number and size of the azimuthal increments determined, NC, from

the number of columns on the patch. The panel geometry is

available at this stage as coordinates in the global axis system.

To convert these into blade radii requires the input of the rotor

center of rotation and this is supplied on Card R5. The panel

edges become the radial boundaries between the blade sections and

the disc panelling and blade segmentation correspond. These

radii form the basis for the rest of the @eometr_ input data.

Figure 18 illustrates how this procedure Is carrled out. The

first radial station, defined by the innermost panel edge, is

assumed to be coincident with the flapping hinge for the articulated rotors modelled here. The rest of the blade geometzy

information is input at the blade radial stations corresponding

to the panel edges.

Blade geometry is defined with three parameters entered on

CARD SETS R6, R7 and R8. These, respectively, are the chord, the

twist and the leading-edge sweep. Each card set contains two

53

J_
o_ poor __

\

RADIAL AND AZIMUTHAL

•"_DISTRIBUTION SET BY

__ i _"VSAERO" PANEL MODEL

- I PUT

DISC PANELLING

DETERMINES BLADE

""../I MODEL AZIMUTHAL

INCREMENTS

CARD SET 11

l

AFT

VIEW FROM ABOVE

_r (TYPICAL)

BLADE SEGMENTATION

FOLLOWS DISC PANELLING

Figure 18. Schematic Relationship between Blade and

Panel Models.

54
basic parts. They are: first, a card containing an indicator,

INSET, which signals if a constant value is to be read (INSET=I)

or if values are to be read at the NR+I defininq radial stations

(INSET=0). If a constant twist is selected, the total twist

should be loaded defined in the conventional sense relative to

the 0.75 radius.

The rotor description is completed by entering the blade

mass distribution, required by the flapping calculation on Card

R9 and the number of blades on RI0.

5.5 Rotor Pelfor_ance and Control.(Cards Rll, RI2, RI3, RI4)

Cards RII through RI4 provide the input which set up and

control the r_or performance.

5.5.1 Rotor Speed and Flapping. (Card RII)

Card RII provides the information which orients the

control axis system in space, sets up the initial flapping,

applies a starting value of collective pitch and sets up the

correct onset flow and rotor rotational speed.

If the default, zero, value for the control axis angle,

ALPHAC, is used here, the program requires that system drag (the

negative of the rotor propulsive force required) be loaded in

Card R13. Since the program calculates the blade coning from the

input mass properties, entry of the blade flapping values, A1 and

BI, completes the rotor orientation input. If the flapping is

constrained, NFLAP-I on Card R4, appropriate values of AIPHAC, A1

and BI, must be input. Otherwise, the calculation may be started

assuming zero flapping, but supplying realistic starting values

speeds the flapping convergence. Input of unrealistic values of

ALPHAC, A1 and B1 can lead to failure to close the flapping loop

and a subsequent crash.

Blade speeds are set with the input of the advance ratio,

the rotor rotation rate, OMEGA, and the hover tip Mach number.

5.5.2 Rotor Blade Cvcllq Control. (Card RI2)

As was noted above in Section 5.3.3 in the discussion

of Card R4, the user has the option, with the parameter, MCOUNT,

of trimming the rotor to target moments (MCOUNT=0, default) or of

setting cyclic controls and taking whatever moments result

(MCOUNT-I). If MCOUNT is set equal to i, values of a and b

must be entered on Card RI2 or values of zero will be assumed.

55
5.5.3 Rotor Loads and Moments. (Cards RI3 and RI4)

Rotor lift and moment targets and the aircraft drag are

entered on Card RI3. If either LCOUNT or MCOUNT on Card R4 are

left to the default value or if any value other than 1 is input,

then target values of lift or moment must be loaded on Card RI3.

The value of drag entered here is the drag area formed by

dividing the actual drag by the dynamic pressure and is used as a

guide in setting up the control axis angle if this is not input

above on Card RII.

Card RI3 is completed with the entry of VCLIM B in areas

where it is derived.

The air density used in the reduction of the loads and

moments to coefficient form is entered on Card 14. If desired, a

rotor tip loss factor may be used in the calculation. This is

also entered on Card RI4. When a tip loss is used, the lift

outboard of the radius ratio, r/rTI P entered on Card RI4 is

varied linearly to zero at the tip. The calculated drag is not

affected.

5.5.4 Airfoil Data Sets. (Card RI5, CARD SETS RI6)

Airfoil data is used by the program in the conventional

manner with table look-up and interpolation for C L and Cn as a

function of local aerodynamic angle of attack and Mach number.

The airfoil sets are keyed to a @articular radius, specified at

input, and during execution the program interpolates between the

data sets appropriate to the nearest radial stations on either

side of the blade segment radius.

At input the parameter, NDSEC, on Card RI5 indicates how

many data sets are to be loaded. Data sets may be loaded or

copied from sets loaded earlier in the input string. This is

indicated by a parameter on the first card of set RI6. With the

parameter, ICOPY-I, a data set is read. With ICOPY-0 the data

set is copied form the previously read set. The radius (absolute) at which the data applies is also entered on Card RI6.1.

The data set follows using the "standard" C81 format, Ref. 2. In

this format data is read as a function of blade section angle of

attack for a range of Mach number. Each set of coefficients is

entered separately. The program interpolates to the local coefficient value at the required value of Mach number and angle of

attack and then between data sets, loaded as a function of span

location, to the correct value.

56

O
6.0 INPUT DATA DECK BLOCKING AND VARIABLE LIST

The VSAERO data deck assembly was described in great detail

in the user's document and will not be repeated here since the

only change in set-up from the operational point of view is the

addition of the rotor data block. This enters the run stream

after the wake information has been loaded.

6.1 Input Summary

The input is divided into the following parts:

(i) BASIC INPUT

General information, operating mode, onset

flow, reference conditions, special options

(ii) PATCH GEOMETRY

Description of configuration surface in components, patches, sections, basic points,

etc., for panel generation

(iii) WAKE INPUT

Wake-grid-planes, type of wake, wake separation line, initial streamwise geometry

(r) ROTOR INPUT

Geometry, iteration and print controls,

control settings, force and moment targets,

and airfoil data

(iv) SURFACE STREAMLINE INPUT

Location of starting point for each surface

streamline

(v) BOUNDARY LAYER INPUT

Reynold's nmaber, etc.

(iv) OFF-BODY STREAMLINE INPUT

Location of starting point and required upstream/downstream distances for each offbody streamline

In the following description, the input variables are first

listed in 6.2 for each of the above parts. Then, 6.3 gives a

detailed description of the function of each input variable.

This is followed in 6.4 by an input flow chart to help with the

assembly of the input data file. Section numbering has been left

common with the original VSAERO document. In the detailed description and flow chart sections, only the rotor input is described. The user is referred to the Program VSAERO User's Guide

for the other sections.

57
6.2 Input Variable List

Basic Input Summary

1

2

2A

3

3A

4(a)

or

4(b)

4A

Text

IPRI, IPRLEV, IPRESS, MSTOP, MSTART, MODIFY

IPRGOM, IPRNAB, IPRWAK, IPRCPV, IPRPPI (only

if IPRLEV-5 on CARD 2)

MODE, NPNMAX, NRBMAX, ITGSMX, IMERGE, NSUB,

NSPMAX, NPCMAX

NROWB(1), I-l, INRBMAXI (only if NREMAX<0 on

CARD 3)

NWIT, NVPI, IBLTYP (if MODE-I on CARD 3)

NT, NHC (if MODE=2 on CARD 3)

(only if NVPI>0 and IBLTYP-0 on CARD 4(a)

(i) NPSETS

(ii) NPCHBL, NBCOL, (KOL(1), I-l, NBCOL)

(Number of 4A(ii) cards - NPSETS)

If HSTART>0 and MODIFY-0; this is the end of

the basic data on a restart run.

7

8

6A

RSYM, RGPR, RNF, RFF, RCORE, SOLRES, TOL

ALDEG, YAWDEG, RMACH, VMOD, COMFAC

ALBAR, RFREQU, HX, HY, HZ (only if MODE-2 on

CARD 3)

CBAR, SREF, SSPAN, RMPX, RMPY, RMPZ

NORSET, NVORT, NPASUM, JETPAN, NBCHGE

58

Zo/m 

20A4

615

515

815

16!5

315

215

I5

1615

7FI0.0

5FI0.0

5FI0.0

6F10.0

515
Car_ Noo

8A (NORPCH(1), NORF(I), NORL(I), NOCF(I),

NOCL(I), VNORM(I), ADUB(I), I_1, NORSET)

(only if NORSET>0 on CARD 8)

8B (i) VORT

(ii) (RXV(I), RYV(I), RZV(I),

I=l, NVORT+I)

(only if NVORT>0

on CARD 8)

8C (NPSPCH(I), NPSRF(I), NPSRL(I), NPSCF(I),

NPSCL(I), I-l, NPASUM) (only if NPASUM>0 on

CARD 8)

8D (JETPCH(I), JETRF(I), JETRL(I), JETCF(I),

JETCL(I), VINCI), VOUT(I), I-1, JETPAN)

(only if JETPAN>0 ON CARD 8)

8E (KPAN(I), KSIDE(I), NEWNAB(I), NEWSID(I), I-l,

NBCHGE) (only if NBCHGE>0 on CARD 8)

Format

515,

2F10.0

F10.0

3F10.0

515

515

2F10.0

415

patch Geometry Input Summary

9

9A

10

11

CTX, CTY, CTZ, SCAL, THET (component card)

CPX, CPY, CPZ, CHX, CHY, CHZ (only if SCAL<0

on CARD 9)

IDENT, MAKE, KOMP, KLASS, PNAME (patch card)

(Note: If MAKE-0, go directly to CARD 16)

STX, STY, STZ, SCALE, ALF, THETA, INMODE, NODES,

NPS, INTS (section card)

5FI0.0

6F10.0

415,

6A4

59
Card Noe

12(a)

(b)

(c)

(d)

(e)

if)

(g)

13

BY, BZ, X (INMODE=I)

BX, BZ, Y (INMODE=2)

BX, BY Z (INMODE=3)

BX, BY, BZ (INMODE-4)

TC, INPUT (INMODE-5 or 7)

H, INPUT (INMODEI6 or 8)

BX, RAD, THET (INMODE=I2)

XRB, NINT (after options 12(e) and 12(f)

14

15

16

NODEC, NPC, INTC, MOVE (use with CARD 12 and

and 137

14A NPCH, NSEC, IB, LB (if NODEC<0 on CARD 14)

14B XPIV, YPIV, ZPIV, HX, HY, HZ, ROT (if MCVEII

on CARD 147

THETA2, THETAI (only if NODES<0 on CARD ii)

NPC, INTC, KURV, NPTIP, NODES, NPS, NTS

(special tip patch) (only if MAKE=0

on CARD i0)

16A (S(I), Y(I), Z(I), I=i, NPTIP (only if KURV>I

on CARD 16)

Format

3FI0.0

FI0.0,

I5

3FI0.0

FI0.0,

I5

30X,

415

415

7FI0.0

2FI0.0

35X,

315,

10X,

315

3FI0.0

_e

17

18

19

2O

Wake Input Summary

X (wake gzid plane stations)

NODE, NPC, INTC, MARK

IDENTW, IFLEXW, IDEFW, WNAME (wake card)

KWPACH, KWSIDE, KWLINE, KWPANI, KWPAN2,

INPUT, NODEWS, IDWC, IFLXL, DTHET

Format

FIO .0

30X,

415

315,5X

6A4

915,

FI0.0

6O

V
J

_o

21 (a) SWPY, SWPZ,

21(b) SWPX, SWPZ,

21(c) SWPX, SWPY,

_les

X (if INPUT--I on CARD 20)

Y (if INPUT--2 ON CARD 20)

Z (if INPUT,.3 on CARD 20)

21(d) SWPX, SWPY, SWPZ (if INPUT=4 on CARD 20)

22 NODEWC, NPC, INTC

23 VIN, VOUT ... (if IDENTW..4 on CARD 19)

R2

R3

R4

R5

R6 .i

R6.2

R7 .i

R7.2

RS.I

R8.2

R9

R10

Rotor Input Summary

IPRCH, ROLL

TITLE

ISPNTI, ISPNT2, IBPNTI, IPTI IPT2

MCOUNT, LCOUNT, NFLAP

XO, YO, ZO

INSET

CHORD(I), I'l for INSET--I

I-NR+I for INSET-0

INSET

TWRATE, for INSET--I

TWIST(I), I-NR+I for INSET-0

INSET

SWEEP(1), I-i for INSET--I

I-NR+I for INSET-0

BMASS

NB

61

30X,

315

8FI0.0

Format

If0,

FI0.0

80AI

8II0

3Ii0

3FI0.0

If0

8FI0.0

If0

FI0.0

8F10.0

If0

F10.0

8F10.0

FIO.O

IlO

)
Card Noe

RII

RI2

RI3

RI4

RI5

RI6 .i

RI6.2

RI6.3

R16.4

R16.5

MU, ALPHAC, OMEGA, MTIP, COLL, AI, B1

ALPHAS (Not used), AIS, BIS

BW, DRAG, PM, RM, VCLIMB

RHO, TIPLOS

NDSEC

ICOPY, YR

TITLE, (NMACH(I), NALPHA(I), I=i,2 )

MACH(J) , J=l, NMACH

ALPHAI, (COI(I,J), J=l,9)

(COI (J) , J=10, NALPHA)

Repeat R16.4 AND R16.5 NMACH times

Repeat to R16.3 twice COI(I,J)=CL, I=l,

CD' I=2

Repeat to RI6.! N_SZC times

8FI0.0

8FI0.0

8FI0.0

8FI0.0

]_i0

I10,

FI0.0

8FIO.O

8_i0.0

8FIO.O

Repeat Rotor Card Set R1 - RI6 for each type-4 patch.

Surface Streamline Input Summary

24

25

F, KP, NS (compulsory input if IBLTYP-I)

(Place one card no. 24 for each streamline)

F, KP, NS (end of surface strem-niine data)

FI0.4,

215

2FI0-4,

215

62

I
Card N_e

26

Bcundary Layer Input Summary

RNB, TRIPUP, TRIPOP, XPRINT, XSKIP

(CARD 26 only present if NVPI>0 on CARD 4(a))

Format

5FI0.0

27

28

29

29A

_O

30A

31

31A

32

33

34

34A

34B

34C

Off-Body Velocity Scan InDut Summary

ymzia t 

MOLD, MEET, NEAR, INCPRI, INCPRJ, INCPRK

(Start of each scan box. Finish the set with

a blank card)

XO, YO, ZO, NP (if MOLD=I on CARD 27)

XI, YI, Zl, NPI (if NP>I on CARD 28)

(ALI(I), I=l, INPII) (only if NPI<0 on CARD 29)

X2, Y2, Z2, NP2 (if N2>2 on CARD 28)

(AL2(1), I=l, INP21) (only if NP2<0 on CARD 30)

X3, Y3, Z3, NP3 (if NP=4 on CARD 28)

(AL3(I), I-l, INP31) (only if NP3<0 on CARD 31)

XI, YI, ZI, ROI, RII, THETAI, THETA2

(if MOLD=2 on CARD 27)

X2, Y2, Z2, R02, RI2 (if MOLD-2 on CARD 27)

NAL, NTHETA, NRAD (if MOLD=2 on CARD 27)

(ALl(I), I=l, INALI)(if NAL<0 on CARD 34)

(ALTHET(I), I-l, INTHETAI; (if NTHETA<0 on

CARD 34)

(ALRAD(I), I-l, INRADI) (if NRAD<0 on CARD 34)

Format

615

3FI0.0,

I5

8FI0.0

3FI0.0,

I5

8FI0.0,

3FI0.0,

15

8FI0.0

7FI0.0

5FI0.0

315

8FI0.0

8FI0.0

8FI0.0

63
Off-Body Streamline Input Summary

Card Noo

35

Y_lLinnle_

RSX, RSY, RSZ, SU, SD, DELS, NEAR

(one card per streamline_ finish with a blank

card)

Format

6FI0.0,

I5

64
R1

6.3 Rotor Input Data Deck Description

Note: All integers are right justified.

I-i0

Rotor patch number

11-20 ROLL

Rotor roll attitude

=0.0 for main rotor

- 90.0 for tail rotor

If0

FI0.0

R2 1-80 TITLE 80AI

r_

.P

R3 i-i0

11-20

21-30

31-40

L%RR21

=i, prints blade radial variation of blade section data

=0, suppresses print

=I, prints blade radial variation of blade loads, etc.

-0, suppresses print

-I, Prints rotor forces and

moment summary at each azimuth

-0, suppresses print

J2.tt

-i, prints input airfoil data

=0, suppresses print

65

If0

If0

If0

Ii0
Card Columns

41-50

=I, prints interpolated airfoil

at each blade section

=0, suppresses print

Format

Ii0

R4 i-i0

Controls cyclic pitch/rotor

moment loop

=0, sets default =3

=i, runs tc set values of Als and

Bls

If0

ii-20

21-30

LCOUNT

Controls collective pitch/rotor

lift loop

-0, sets default =6; recon_end

default or 13

NFLAP

Controls blade flapping/tip path

91ane loop

=0, sets default _4; recommend -4

for main rotors, =i for tail

rotors

If0

Ii0

i

R5 1-30 xo. Y0. zo

Rotor centeL' in body axis system

3FI0.0

66
r.

Card

R6 (SET)

6.1

6.2

R7 (SET)

R7.1

R7.2

R8 (SET)

RS.I

R8,2

R9

RI0

Columns

i-I0

1-80

i-I0

1-80

i-i0

1-80

i-i0

I-i0

Inset =-i, constant chord; read

only 1 value on 6.2

Inset =0, variable chord; read

(NR+I) values on 6.2

Blade chord values, dimensions in

feet

Inset 5-1, constant twist rate; read

total twist from 7.2

Inset 50, variable twist; read (NR+I)

values on 7.2

Blade twist values

Inset 5-1, total twist in Col. i-i0

Inset50, section twist relative to

0.75 radius, in degrees

BLADE LEADING-EDGE SWEEP

Inset 5-1, constant sweep; 8.2

blank (sweep 5 0.0)

Inset 50, variable sweep; read

(NR+I) values from 8.2

S%Jep values

Inset 5-i, blank card

Inset 50, leading-edge sweep

positive aft in degrees

Distribution assumed constant;

dimensional in slugs/ft.

NUSBER OF

67

Format

If0

8FI0.0

IlO

8FIO.O

IlO

8FI0.0

FIO.O

Ii0
Card

RII

i-I0

11-20

21-30

31-40

41-50

51-60

61-70

ROTOR PARAMETERS

ADVANCE RATIO

CONTROL AXIS ORIENTATION

=0 if drag value on Card 14 used

= value if tip path tilt entered

(degrees positive aft)

rotor rotational speed (radians/

sec.)

HOVER TIP MACH NUMBER

_NPUT COLLECTIVE PITCH (degrees)

A1

Sl

Input fore and aft flapping

(degrees)

Input lateral flapping (AI and

B1 can be input = 0.0)

FI0.0

FI0.0

FI0.0

FI0.0

FI0.0

FI0.0

FI0.0

RI2

i-I0

11-20

21-30

CYCLIC CONTROLS

SHAFT AXIS ANGLE (not used)

AIs

Fore and aft cyclic input (deg.)

sls

Lateral cyclic input (deg.)

FI0.0

FI0.0

68
RI3

RI4

 hmaa

i-i0

11-20

21-30

31-40

41-50

i-i0

11-20

RI5 I-I0

ROTOR LOADS AND MOMENT VALUES

GROSS WEIGHT (ibs.)

DRAG

(D/q) square feet

ROTOR PITCHING MOMENT TAR_

(set MCOUNT=3 on Card 3)

(ft.-ibs.)

ROTOR ROLLING MOMENT TARGET

(set MCOUNT-3 on Card 3)

(ft.-ibs.)

V CLIMB (ft./see.)

MISCELLANEOUS

(slugs/Ft.3)

TIP LOSS FACTOR

Linear tip loss applied outside

input value, R/RTip

Default =0.0, no tip loss

NDSEC

Number of airfoil data sets

following

Format

FI0.0

FIO.O

FIO.O

FI0.0

FI0.0

FIO.O

I10

RI6 AIRFOIL DATA SETS

Repeat ND sec. times

Note: Repeat R1 through RI6 for each rotor, type-4, patch used.

69
J

CARD SET RI6:- AERODYNAMIC SECTION DATA. These data tables are

input in the standard format currently used in

the Rotorcraft Flight Simulation Program, C-81,

Ref. 2.

Repeat NDSEC times.

_t

ii

!

CARD 16A:- CODV Control Inteaer.

D uL u 2.Um

1-5 ICOPY(IDSEC) 0 Complete aerodynamic tables are read

in for this section

ID Sectional aerodynamic data is copied

over from previously defined section

ID

Note: If ICOPY(IDSEC)>0, the rest of CARD SET RI6 is omitted for

this section.

CARD RI6B:- Title @nd Control Card.

columns

1-30 TITLE ANY Alphanumerical title of sets of tables

31-32 NMACH (i) 3-18 Number of Mach number entries in C Z

table

33-34

35-36

NALPHA (i) 3-99

NMACH (2) 3-18

Number of angle-of-attack entries in

C table

Z

Number of Mach number entries zn C d

table

37-38

39-40

NALPHA (2) 3-99

NMACH (3) 3-18

Number of angle-of-attack entries in

C d table

Number of Mach number entries _n C

table. Not used. Set=0 m

41-42 NALPHA (3) 3-99 Number of angle-of-attack entrles in

C table. Not used. Set-0

m

7O

)
NOte: CARD SETS RI6C through RI6E are repeated as a group three

times for C£, C d and Cm; that is, in the following descriptions

K = 1 C Z

K = 2 C d

K - 3 C

m

Not used in rotor/body performance

calculation at this time

CARD 16C:- Mach Number Entries•

 nluaam

8-14

15-21

22-28

64-70

Note:

Value

MACH (I) arbitrary

MACH (2)

MACH (3 )

MACH (9 )

 % UzutQn

Lowest Mach number

Next highest Mach number

Next highest Mach number

Next Highest Mach number

Additional card may be required with same format to input

NMACH(K) values of Mach numbers•

CARD RI6D:- Anule-of-Attack/Coefficient Data.

Columns

1-7

8-14

15-20

22-28

value

ALPHA(K) arbitrary Angle of attack, degrees

COI (K,I)

COI (K,2)

COI (K,3)

Coefficient at MACH(1)

Coefficient at MACH(2)

Coefficient at MACH(3)

64-70 COI (K,9) Coefficient at MACH(9)

71
CARD RI6E:- Continued Coefficient Data.

c hu=m

8-14

64-70

Value

COI(K,10) arbitrary

COI (K,18)

Coefficient at MACH(10)

Coefficient at MACH(18)

Notes: i. CARD RI6E included only if NMACH(K)>9.

2. CARDS RI6D and RI6E repeated NALPHA(K) times for each

angle of attack•

72
o

REFERENCES

Maskew, B., "Program VSAERO User's Guide", NASA _,

Prepared for NASA Ames Research Center under Contract NAS2-

8788, 1983.

Davis, J.M. et al., "Rotorcraft Flight Simulation with Aeroelastic Rotor and Improved Aerodynamic Representations",

Bell Helicopter Textron, USAAMRDL 22_ (A, B and C),

U.S. Army Air Mobility Research and Development Laboratory,

Fort Eustis, VA, June 1974.

73
APPENDIX: SAMPLE CASE

Contains: I. Samp]e Input

2. Sample Output

Note: The case has been chosen to be roughly representative of

the H-34 rotor as tested on the Ames Rotor Test Module.

The test module has been generated as a body of revolution (see Section 3.1.2). The rouor has been run in a

requested thrust, fixed cyclic mode with the control axis

tilt input. This sets the tip path plane angle and determines the propulsive force. The output has been somewhat truncated but a sample of each section has been retained. Only output specific to the rotor portions of the

program is retained. For body output examples the user is

referred to Reference i.

74
i. SAMPLEINPUT

75
ORI(_ItNAL PAGE _

OE POOR QUALITY

ioz

_r

oo

°°o

00 n _, _1U 0 _1"_l' _ m _ 0 _ _ 0 ,0 _. N -._ O, _- _ _ 0 _, o_

00000000 ............ 0000o00 _ _0

0oo0000o0000oo O00c_oo00000o.-_ _no 0 n

_'_ ._._u_ s _,u_

A

76

_o

o

O0
ORIGt_iAL PA_c ._

OE POOR QUALITY

0

E_

0

0

Z

0r}

0

r,.

0

Z

wl v

o

g.I

w

0 _r_ 0

:I

QO

0

m

0

0_'_

d

0

O _

o

O"

n

g 8

6

- 0

z

m

0

E-I

0

0

Z

_.1

v

41

,0

0 0

-,o

o0 _o_

o r_oo

It

I,,,

m

0

T ? T ''°0 io

o - i, O0 00_o

0 I

o

o

0

,,°

77

©
2. SAMPLE OUTPUT

78
C_RIGtt'IAL PAC_ IS

OF POOR QUALITY

m

i

0

O"

0

O.

q.

,o

A

4

0

.3

tal

m--

t

0

u

_1

A

u

_0

_.0

-JO

wO

_0

0

,- 0

_o

_-0

0

_-0

D

wO

_ Iz:O

_ o

A

0

0

0

0

.oe

•

_," _ MO

:s _

_ _: oo

.,

"_.!i!_l!°i.

79
ORIGINAL PA(_E |$

OF. POOR QUALITY

>,. b.

"O

IB

÷

z,rrn

Z

L_lrt

J

Z ,._ irt

,0

,.q

jrd,_

0.-,_

U

Z

Z

q:

_J

_ _(._

C]

Z

o _

0 0

•4 n _i -0

t_ -" 0

0 (0 u CO

80
I

W

(

Z

A

U

W

,,,r

23

Z

OLRIG_AL PAGE I_

OF_ POOR QI_JALITY

!

b

• Z

• t,I

• 7

. _

Q t_

• Z

• W

: I

• II.

• Z

: a

• _

• f

• W

• J

• I

" i

0

0

Qg

m

0 0

•,, 0 (_ g

0

o o

3 3 oo

o _ o°

o g 0

I,- I--

bd W

Ul t_

Z _ _

! ii i ii l

0 0

0 a o o

o

_o _o o° _ _o g

: o _o _ i_o o

0 • 0 >"

_-0 _ Z )-0 Z

0 G."_ 0 Ck_% ILl O0 _k"_

A

10

Z

II l 1 _

, _1 _

_0

o

WO

_0 _ _0 _0

_0 0 _0 _0"0 _0 _ 0 Z _0

81
O1_

0_3

0"G0

.-,M

OOO

OOO

000

O" O. O,

000_

or_

o_

8_

41,1r

I

OOOO

m

O.0

I .0

OO_O

1_40,

i 01'_b'3

url

O

W

N

Lg

O

N

Z

_d

>

1"

O3

Z

.J

('3

O

I

Z

r

W

I

|

W

>

,E

O

Lg

U=

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O.00 _

OOOO

OOOO

o0_r

_.._

0_

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0 ..

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82

_ORIGI_IAL PAGE ,_

0E F_3OR QUALITY
@RIGINAI.PA(._ i_

91: POOR QUALITY

)
L'

t

g-i

I.-

U

Lu

el

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o

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o

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00000

00000

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0000

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U],-.RI r'lq" _ .0;_ t_ O- 0 ,-._

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UOdo0--O00OOO

I

_ _ _0__ _

Illllllllll!

000000000000

0000000000 O0

>ooooooooooo0

_O_M__

O_M_O_

I|IIIIIIIIII

_0_ _ _00

__ll

IIIII

--_ _0_0--_

U •

_oooooooooooo

ORIG_AL PAGE i_,

OF POOR QUALITY.

tO

II|J|

0

_0_0__

M___

oo_-_-_-m_mN

III

¢--_0=_oo

_ , _ _O_M

Z

e___O_
86
i L

ORIGINAL PACt_ Ib

OF POOR QUALITY

n_

O

O

t¢

qr

i

Ii10

u

CqP

b. 0"

I

Z

mO

n

°

U3

0

¢,,

P_

0

0

E_

:/1

v

87
1. _No. 2. Goveuw_ A_m_n No. 3. n_pWm's Cmlo0 No.

CR- 177340

4. Tit_ Incl SulNi_

Study for Prediction of Rotor/Wake/Fuselage

Interference

Part II: Program Users Guide

7. Autho#¢s}

D. R. Clark

B. Haakev

9. Per_ Orl_imtion Nameand,k_Ir_

Analytical Methods, Inc-.

2047 - 152nd Avenue, N.E.

Redmond, WA 98052

12. Sponsoring A41oncv Name and Address

NASA Ames Research Center

Moffett Field, CA 94035

Harch 1985

L _Oqmm_ _ No.

I0. Wefk U_ me.

11. CO_ Or IBnlnt No.

HAS 2-10620

13. Type of _ and I_ri_l COvmld

Final, 6/1/80-11/1/83

14. sm_,_o,_ ,_encvCod_

505-42-11

15 SupplementaryNotes

Point of Contact: Technical Monitor, Charles A. Smith

M/S 247-I, NASA Ames Research Center

Moffett Field, CA 94035 (415)694-6714

16 A_troct

A method has been developed which allows the fully coupled calculation of

fuselage and rotor alrIoads for typlcal helicopter configurations in forward

flight. To do this, an Iterative solution i_ carried out based on a conventional panel representation of the fuselage and a blade element representation of the rotor where fuselage and rotor singularity strengths are

determined simultaneously at each step and the rotor wake is allowed to relax

(deform) in response to changes in rotor wake loading and fuselage presence.

On completion of the iteration, rotor loading and inflow, fuselage singularity

strength (and, hence, pressure and velocity distributions) and rotor wake are

all consistent.

The results of a fully coupled calculation of the flow around representative

helicopter configurations are presented. The effect of fuselage components cn

the rotor flow field and the overall wake structure is detailed and the aerodynamic interference between the different parts of the aircraft is discussed.

In particular, the flow field developed by the rotor head is followed and the

effect of a rotor head cap and pylon modifications in redirecting the rotor

head flow are illustrated. Good correlation between measured and calculated

fuselage alrloads in low-speed fllght is achieved and correspondence with

observed flow field behavior is demonstrated.

Rotor Air Loads

Fuselage Rotor Loads

Helicopter

Aerodynamic Interference

19 Semq;WCk_f. _ t_ _eoqtl

UNCLASSIFIED

Subject category: Ol

Unlimited

m. ba_iw _. I_ _ mill

UNCLASSIFIED

_. No. _ _em

82

"Fo_ tide by the NJllo_t41Toehm/_l Info_nltiom _. _;r_nl_ield. Viqpnio 2_!14;1

2"J. I_le__