I

___ NASA CONTRACTOR REPORT 177336

" EXPERIMENTAL STUDY OF MAIN ROTOR TIP

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GEOMETRY AND TAIL ROTOR INTERACTIONS

(I&S& Ca 7 3 ¢I 11 _XpE_IB314T&L STUDY H85-223_4

OF B&Ig $OTOa TIP GSORZTRZ AND TAIL ROTOU

ZiliTmR&CTICES IN ltCV_R. VCT'U__t 1. T_XT AVD PI(_UBES Progress I_eporc, Auq. 1982 NoV. UnclEs ]

1983. (Sikorsky _izc_a_ Stra_£ord, Conn.) G3/_1 201_7

p. T. Balch and J. Lombardl

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• ° - - - x .

i CONTRACT NA$2-11266

' '.2 :- - "

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_" NASA CONTRACTOR REPORT 177336

:i EXPERIMENTAL STUDY OF MAIN ROTOR TIP

,3 GEOMETRY AND TAIL ROTOR INTERACTIONS

..... IN HOVER. VOL I - TEXT AND FIG, IH1ES

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_9

_!ii D.T. Balch "

!_ J. Lombardl

Sikorsky Aircraft Dlviston

ii United Technologies Cocporatlon i

Stratford, CT 06602

',il

_il Prepared for

•!_ Ames Research Center

_ • under Contract NAS2-11266

Q

i NationalAeronauticsand

- Sl:)aceAdministration

"_ AmesResear©hCenter

";i Moflett Field,California94035

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: PRECEDING PAGE BEAR_ _ ]NEM_D

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TABLE OF CONTENTS

i ' ABS_CT ...................... i

i SUMMARY ...................... 1

INTRODUCTION .................... 3

@

LIST OF TABLES ................... 4 I

• LIST OF FIGURES .................. 5 ,+

; LIST OF _YMBOLS 9

i TEST FACILITIES, APPARATUS AND PROCEDURES ..... i0 r

Basic Model Test Rig.... !

_i Model Hover.Test Facllity.

_"i Data Model Acqu Rotor lsltlBlades on/Reduct1?n and Tips i ! i i i i i i i i

Test Procedures ................

TEST RESIILTSAND DISCUSSIONS ............ 19

Data Repeatability/Scatter ..........

Isolated BLACK HAWK Maln Rotor ........

Isolated S-76 Main Rotor ...........

Main Rotor and Tail Rotor ...........

CONCLUSIONS 28 'i

REFERENCES 30 li

TABLES ....................... 32 i

FIGURES ...................... 37

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- _ .... "_-_-" --_+ - + ":"_ _+ -- +--+'.'..'+_'r+. " -- '+ "_ -- + --'
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iJ The topic of Main Rotor/Tail Rotor/Airfr_e interaction in hover

.L has been identified as being one _at could increase operational

i! efficiency of future rota_ wing aircraft. However, _e question

' of _e sensitivity of some of _e hover improvements to be gained

ii ° by _e use of advanced geomet_ tip configurations, when operating

' . in close proximity to a tail rotor, needs to be ad_essed. To

_! assist in identifying and quantifying _e _pact of _e tail rotor

!.) on the improvements in main rotor hover performance attain_le by

:! using advanced geome_ rotor Up configurations, NASA _es

.... awarded Sikorsky _rcraft Contract. N.AS2-11266 to _dertake a

series of model scale tests. The Initial phase of _e investiga-

_ tion involved main rotor only tests wi_ two current advanced

i_ teclmolo_ rotors (representing a scaled _-60A B_CK _ rotor

_i( _d a scaled S-76 rotor) and eight di.fferent tip configurations - . :

_.-: _ee for use on _e B_CK _ and flve for use on _e S-76. In i

'_ _is phase _e full impact of _e tip geome_ changes on _e W

rotor hover performance, as a .f_mction of rotational tip Math

n_er and gro_d effect, were Investigated using all eight tip

op_ons. From _ese results, four of _e more advanced tip

confiqurations were selected for _e second phase, wi_ two tip.s

each being tested on _e two main rotors. This test assessed maln

rotor performance in _e presence of an .operating tail rotor

(- (configured both as a _actor and pusher t.ail rotor). The tip

Mach n_er and gro_d effect ranges were identical for _e two

tes_. Details of _e test configurations investigated are given

in T_le 1. i

The .peak isolated rotor performance was obtained wi_ a tip _at i

_) co_ined sweep, taper and _ed_. al. _en tested in _e presence

/'I ogreater f _e _tail rust rodegradati tor, hoowever, n due _tiso _e tiptailconfi rotguorraticoompared n e_ibited to _e .:il

o_er tested tips. The B_CK _ rotor, when using _e do_le

_ swept tip wi_ _edral, e_erienced 0.6_ more t_rust loss due to

_e tail rotor _an _e rotor did when using _e do_le swept tip.

_ The S-76 rotor, when using _e swept tapered tip wi_ a_e_al,

_. e_erienced 0.8_ less _st loss due to _e tail rotor _an _e

rotor did when using _e 60_ tapered tip. All tips, out of ground

, - effect., on average showed a rotor performance loss in _st of

approx_mately 2X when s_jected to _e inf?.uence of _e tail

• rotor. The use of eider a pusher or t_actor tail rotor at any of

. _e test tip Mach n_ers did not influence _e magnitude of _e

• interference measured on _e S-76 rotor but _d on _e B_CK _

rotor. Moving _e rotor into ground effect did redu,:e _e impact

. of _e tail rotor on _e interference by approximately .7_.

, Again, all rotor tips produced a similar trend.

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!_: Overall, the test results showed that the tail rotor effects on •

,_ the advanced tip configurations tested are not substantially

:I different from the effects on conventional tips, and the benefits

'J obtained from advanced tips should be retained even when operating '

in the presence of a tail rotor.

_ The customary system, of units was. used for princ,ipal measurements ,

ii and calculations. Expressions In both SI unlts and customary ,

units are used with the SI units stated first and the customary

oi!i tuaits afterwards, in parenthesis.

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INTRODUCTION

In recent years the topic of _ain Rotor/Tail Rotor/Airframe

'_ ' interaction has received more and more attention. The two areas

:_ of interaction in hover and in forward flight have, for the most

part, each been addressed separately. In the area of hover inter-

_ ' action, two major studies were fur.ded by NASA Ames and documented

ii , in References (i) and (2} by Sikorsky and Bell respectively. They

concentrated on proving that the interaction existed and quantify-

"_ ing the magnitudes of the mutual interferences involved. In

I addition, both reports looked at the impact of a number of hell-

• copter preliminary design variables on the interactions. Included

in the main rotor design variables for the Reference (I) Sikorsky i

test were four tip configurations. The tip configurations includ- !

ed a 20 e swept tip, a 35 ° swept tapered tip, an elliptic tip and a !

wisquare th othtip. er coUnfnfiogurtuna ratitoely, n differences, the tips wereandeachen h cmount e nedo soynstema _ototicrs

i effect of the tail rotor interaction as a function of tip geometry

was possible, i

The advent of advanced composite materials, has removed some of _

the previous design limitations on main rotor tip geometry. Rotor

designers now have the flexibility to incorporate the advanced tip

_ designs evolved by the aerodynamicists. In this regard, the topic

.... of optimum main rotor design for isolated conditions has received

considerable attention in the last few years. References (3) t

through (14) present

:_-_ conducted on the subjeth+e__reVisrtually ults of a_l number of theseof stud suchies,studies how- (

ever, have concentrated on the performance benefits of the new tip

shapes without considering the potential degrading effect due to

the necessary tail rotor operating close by. Their flow fields )i

have not been addressed theoretically, because of the complexity [_

of the flow fields involved. This report does, however, address I

the topic via the model scale test approach, and the result can be

applied to equivalent isolated main rotor performance that was

generated either from analysis or test.

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LIST OF TABLES

:! Table No. Title Paqe No.

-, 1. Test Configurations 32

2 Model Rotor Characteristics 33 ,

x_

_, 3. Main Rotor Alone Performance 34 ' V_

, Increases

4. _ Loss of Main Rotor Thrust due 35 •

to Addition of Tail Rotor, OGE

, 5. _ Loss of Main Rotor Thrust due 36 !

_ to Addition of Tail Ro_er, M t = 0.6

a _

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LIST OF FIGURES

Fiqure No. Titl_____ee

* 1. Model Test Tell Hover Facility

2. Model Test Cell Hover Facility

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t . 3. Typical Main Rotor C_/Sigma -

C_Sigma Relationshi_ ,_

4. Typical Main Rotor Full Range .

• Figure of Merit - Ct/Sigma

Relatio:mhip I

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5. Typical Main Rotor Exp.anded Scale

FiRelaguretionship of Merit - Ct/Slgma ii

i_-i 6. Typical Tail Rotor C+/Sigma -

ii _ C_Sigma Relationshi_

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7. BLACK HAWK Rotor Geometry

8. S-76 Rotor Geometry

I9. Tip Configurations Tested

10. Math Number Trends, OGE, BLACK HAWK

-: Rotor with 20 ° Swept Tips

11. Mach Number Trends, OGE, BLACK HAWK

Rotor with Double Swept Tips

12. Mach Number Trends, OGE, BLACK HAWK

Rotor with Double Swept Tips with b

Anhedral

13. BLACK HAWK Tip Comparison, OGE,

Mt = 0.55

14. BLACK HAWK Tip Comparison, OGE,

Mt = 0.6

* 15. BLACK HAWK Tip Comparison, OGE,

Mt = 0.65

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_, LIST OF FI_.S (Cont'd) "

i _ Fiqure No. Title

.i 16. BLACK HAWKTip Comparison, IGE

I Z/R = 1.2, Mt = 0.6

. 17. BLACK HAWKTip Comparison, IGE

:! Z/R = 0.75, Mt = 0.6

=_ 18. BLACK HAWK Rotor, Ground Effect

'" Augmentation "

: 19. Math Number Trends, OGE, S-76 Rotor

with Rectangular Tips

-=_ - 20. Mach Number Trends, OGE, S-76 Rotor

_ with 60_ Tapered Tips

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21. Mach Number Trends, OGE, S-76 Rotor i

i_ with 20 ° Swept Tips

['i ....

_'_ 22. Mach Number Trends, OGE, S-76 Rotor

!I.... with Swept Tapered Tips

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23. Math Number Trends, OGE, S-76 Rotor _ _

.... with Swept Tapered Tips with

_ Anhedral i

i-i 24. S-76 Tip Comparison, OGE, Mt = 0.55 i:i

_'_ 25. S-76 Tip Comparison, OGE, M t = 0.6

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="i 26. S-76 Tip Comparison, OGE, Mt = 0.65

"i 27. S-76 Tip Comparison, IGE Z/R = 1.2,

- Mr-06 h

/. 28. S-76 Tip Comparison, IGE Z/R = 0.75,

"_ Mt = 0.6

: 29. S-76 Rotor, Ground Effect Augmenta-

" tion

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30. Tail Rotor Effect, OGE, M_ = 0.55,

- BLACK HAWK Rotor with Double Swept

Tips

:i 31. Tail Rotor Effect, .OGE, M_ = 0.6,

"_ BLACK HAWK Rotor wzth Double Swept

i Tipz

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. LIST OF FIGURES (Conrad)

Fiqure No. Title

' 32. Tail Rotor Effect, .OGE, M_ = 0.65,

BLAC_ HAWK Rotor wlth Double Swept

Tips

g

• 33. Tail Rotor Effect, .OGE, M_ = 0.55,

BLACK HAWK Rotor wlth Double Swept

Tips wit_ Anhedral

" 34. Tail Rotor Effect, .OGE, M_ = 0.6,

BLACK HAWK Rotor w_th Double SWept

Tips with Anh=.dral

35. Tail Rotor Effect, OGE, M_ = 0.65,

BLACK HAWK Rotor with Double Swept

Tips with Anhedral

36. Tail Rotor Effect, IGE Z/R = 1.2,

M_ = 0.6, BLACK HAWK Rotor with

D_uble Swept Tips

37. Tail Rotor Effect, IGE Z/R = 0.75,

M_ = 0.6, BLACK HAWK Rotor with

! D_uble Swept Tips

38. Tail Rotor Effect, IGE Z/R = 1.2,

M_ = 0.6, BLACK HAWK Rotor with

D_uble Swept Tips with Anhedral

39. Tail Rotor Effect, IGE Z/R = 0.75,

M_ -- 0.6, BLACK HAWK Rotor with

D_uble Swept Tips with Anhedral

40. Tail Rotor Effect, OGE, M_ = 0.55,

S-76 Rotor with 60YoTapered Tips

41. Tail Rotol Effect, OGE, N_ = 0.6,

S-76 Rotor with 60_ Tapered Tips

42. Tail Rotor Effect, OGE, M_ = 0.65,

. S-76 Rotor with 60_ Tapered Tlps

43. Tail Rotor Effect, OGE, N_ = 0.55,

S-76 Rotor with Swept Tapered Tips

. with Anhedral

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LIST VZUUaES(Cont'd) i

........

Fiqure No. Title , r

44. Tail Rotor Effect, OGE, M_ = _.6,

S-76 Rotor with Swept Tapered Tips

with Anhedral

45. Tail Rotor Effect, OGE, M_ = 0.65, ,

- S-76 R_tor with Swept Tapered Tips ,

with Anhredral

46. Tail Rotor Effect, OGE, M_ = 0.55,

S-76 Rotor with Swept Tapered Tips

47. Tail Rotor Effect, OGE, ML = 0.6,

!_T_:.:_ S-76 Rotor with Swept Tapered Tips

_=:! 48. Tail Rotor Effect, OGE, M_ = 0.65, )

t_') S-76 Rotor wlth Swept Tap_r_-d TIps

49. Tail Rotor Effect, IGE Z/R - 1.2,

M_ = 0.6,.S-76 Rotor with 60Yo

T_pered Tips

50. Tail Rotor Effect, IGE Z/R = 0.75,

M_ = 0.6, .S-76 Rotor with 60_

T_pered TIps _:

51. Tail Rotor Effect, IGE Z/R = 1.2,

• M_ = 0.6,. S-76. Rotor with Swept _

T_pered Tips wlth Anhedral

52. Tail Rotor Effect, IGE Z/R = 0.75,

M_ = 0.6,. S-76.Rotor with Swept

T_pered Tlps wlth Anhedral

53. Tail Rotor Effect, IGE Z/R = 1.2,

N_ = 0.6, S-76 Rotor with Swept

T_pered Tips

54. Impact of Tail Rotor on Performance

Improvements

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" LIST OF Siq4BOLS

/'i a Speed of sound

"T

•T'I' 4

_I b N_er of blades = 4

r c Blade chord

:i'i Cq Rotor torque coefficient =

;W "

:i: T

:.. • Ct Rotor _rust coefficient = np_2R4

" i

i![i FMR Figure of Merit = ( Cq

b

_;'! MT Rotor rotational tip Mach n_er = _R _

/!"

.;' Q Rotor torque

"!_ , I

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='... T R Rotor radius

: _"=i Sigma Rotor solidity = n-R

T Rotor Thrust

: t/c Airfoil maximum thickness to chord ratio

,./

....•.- Z Distance between ground plane and the centroid of

,,, the rotor hub

,: p Mass density of

i

, _ bc

•. o Rotor solidity = -- /- nR

• _ Rotor rotational velocity, radians per second

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'-, TEST FACILITIES, A_PARATUS AND PROCEDURES

": Basic Mode I Test Rig

• The Basic Model Test Rig (BMTR) is a self-contained helicoptez

test rig which can handle a range of rotor systems and fu_,.lage

i_ skins as well as model support schemes.

/_'° The rotor power, rotor control and data measurement systems are

completely self-contained. All that is re_aired to provide a

,, working test configuration is the attachment ,ofpower, hydraulic

o control and data signal lines and a support- structure

:_ The main rotor of the BMTR is driven by a 90 HP 3 phase synchro-

.. nous electric motor through a reducing gear box. The BMTR trans-

_/ m_ssion was modlfle_ during thls contract• This modification

"_ii.l involved upgrading the transmission t-omake i'_ _pabl :, of handling

I the 90 lip motor used in the test rather than the 60 :._'miot?or used _:

i_.:l preViously• Not only does the new transmiss'.on h ,, e a greater :

_I horsepower capability, but it is also in a milch m__ ,ampact form.

°:i. The 90 lip motor mounting position was c,_....._._ed" ,.ahozizontal to

:; vertical on the modified traDqmissJ _ he sl_p ring, ptical

, encoder and control mixer bo: ,r_,_d unchanged during the

._i transmission modification. The ,oad cell, used to measure main

:;_." i rotor torque was changed from a i_vere Model USP1- • 5-B-5283 to an '

_.... Interface Model SSM-25.0. As a .result o.f these modifications it i ! i

"_,,. was found, when comparing otherwlse identical pre and post modlfl- :'7

:_ cations runs, that main rotor thrust at fixed pover dropped by

appz_x'mately 2_ at the higher thrust levels. However, close to

'.._ identical pre and post modifications can be obtained throughout

the thrust range by reducing the pre modification measured lifts _

i: and tor__es by 4.5_. This data adjustme.nt has been applied to all

-: pre-mod_flcation data presented zn th_s report. The resulting

main rotor Figures of Merit are now in line with those obtained by

_'_ other model test facilities

: The main rotor forces and moments are measured on a six element

_i strain gage balance (Task 1.5 Mk XlX). Rotor torque is measured

by the separate load cell described above.

_ All tail loads are measured separately on _not_er 6 component

balance, a Task Model 2.0 Mk III straln gage balance. Th.ls

" balance measures the net system thrust on the tail rotor (ta_l

_ rotor thrust plus thrust recovery, less fin side force reaction) .

as distinct from tail rotor thrust alone• The tail rotor power is

_ supplied by a 20 horsepower 3-phase synchronous direct drive

' i electric motor•

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Ha_,. rotor control inputs are made via jack screws and a conventional rotor swashplate. The control inputs are measured at the

outputs from the jack screws by potentiometers. The cyclic inputs

are monitored to give zero flapping as measured on a blade flap

• potentiometer. Tail rotor inputs are made similarly-with a. jack

screw and a non-tilting swashplate. Th _- tail collective inputs

are also measured via a potentiometer on the p.ushrod. It should

• be noted that because of the effects of flexzbllity of the system

: . the methods of blade pitch measurement used do not gener_lly give

the actual blade pitch angles. ,

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The effects of the tail rotor "delta 3" angle, (the pitch-flap '

• coupling), are not included. This "delta 3" angle (of 45 °) has

the ef_'ect of giving an actual blade pitch angle different from '

the input angle. While the absolute blade angles cannot be

. defined exactly, the changes in blade angles due to interference i

effects are correctly measured, i

H

The main rotor collective was set to zero during the installation

t of blades. Any adjustment in individual blade pitch that was

needed to bring the blades into track (all blades following the

same tip path plane) could shift this reference point slightly.

When the tail rotor was changed from tractor to pusher configuration, the drive motor and control inputs were f.lipped over. This

causes a change in the sense of the control input jack screw and

potentiometer. During data reprocessing, this shift in tail rotor

collective slope (and zero) caused by the tail rotor reconfiguration has been accounted for.

The main rotor torque measurements are made separately using a

load cell attached between the transmission box and the model

frame. However, the tail rotor shaft torques were not measured !

separately but were measured on the pitching moment elements of

the tail balance. This pitching moment was assumed to be equal to

the applied tail rotor torque.

To minimize any errors in this approach, all the runs were conducted without the stabilator to eliminate any download contamina-

: tion of the pitching moment re_ding.

The BMTR is capable of handling the fuselage skins of any appropriately scaled aircraft. The 1/5.727 scale fuselage of the

UH-60A BLACK HAWK was chosen for this contract• The removable

( • skins are not hard mounted to the BMTR structure. This makes the

;I skins independent of the main and tail balances •

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Model Hover Test Facility

The tests involved in this study were conducted on the Sikorsky

Model Hover Test Facility using the Basic Model Test Rig (BMTR). - '

This test facility includes the hover pad, the .model assembly area

and the data acqulsltlon, recordlng and processlng systems.

The five sided hover test cell Figures 1 and 2 measures 18.0m (59

ft) long by 12.8m (42 ft) wide and is enclosed by nine 9.1m (30 ,i

ft) high garage-type doors. These doors are used to minimize the i

impact of _,inds and can be individually set to any desired height.

Previous to this contract, runs were made at various door heights

to determine the opt._mum settings to minimize wind induced rotor "

perform.ante effects for all wind conditions below 20 knots. A

door helght of 1.2m (4 ft) was selected for the majority of the

test. Occasionally a run was made with the doors fully opened to _i i_! verify that the measured performance was not influenced by the

_i proximity of the enclosure doors. !

'_i A major feature of the hover pad is the hydraulic ram on which the

_ BMTR is mounted. This ram can be raised or lowered with a 7.62m

(25 ft) stroke capability. The fully lowered ram puts the model

I rotor head 105 cm (41 in. ) above the ground. This cOrresponds to

_ a height to radius ratio (Z/R) of 0.75. This value was also used

_"-_- as one of two in-ground effect (IGE) conditions. The fully |

extended ram positions the model rotor head to a Z/R value of _

approxlmately 6.5. This value is well _n excess of the height !

_ needed to simulate out of ground effect (OGE) hover° Since a Z/R ,

of 6.5 puts the model rotor very close to the top of the enclo- .

sure, a Z/R value of 3.0 was selected for the OGE segments of the

test to insure a minimum of upper flow disturbance. !

An airspeed anemometer and weather vane are mounted directly above !

the model on top of the enclosure. With the doors open, the

airspeed reading and wind direction indicator match the readings

taken in the Sikorsky Aircraft control tower. However, with the

doors at normal running height, the anemometer reading is considerably lower than the true outside airspeed. Comparisons of

rotor performance changes with anemometer readings under high

outside wind conditions have shown that the anemometer reading is

an accurate indication of the wind condition that the rotor

experiences. Anemometer readings of 2-4 kph (1-2 knots) were

established as acceptable for taking performance data which was

independent of the ambient wind conditions.

The controls for the BNTR are located in the control room of the

test facility building. Independent controls for the main rotor

and tail rotor RPM's and collective angles are used. Main rotor

lateral and longitudinal cyclic control is also available.

• "I
, The main rotor electrical power supply (3-phase, variable frequency) was a Servo Optics 440V 500A.solid state "Static Drive"

unit. The Sikorsky 440V 200A "Varidrlve" unit was used to power

,, the tail rotor. This unit was fabricated from components supplied

by various manufacturers.

il The main voltage supply used to drive the HP 9845T computer, the

' " NEFF signal conditioning unit and the strain gage power supply was

• stabilized using a Deltec Corporation DLC 1860 signal conditioning

1 unit.

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Data Acquisition and Reduction _ i

All data acquisition and on-line processing tasks were performed P

by the Experimental Aeromechanics Model Rotor Test System. This

system utilizes a Hewlett-Packard 9845T micro-computer coupled

wlth .a Neff System .620 Data Acquisition System. The HP9845T _s a

16 blt computer whlch is capable of complete control over monitoring model integrity as well as acquiring, processing, and

: storing performance data. The data acquisition program used in

this test acquires the following parameters from the Neff system:

• Six component main rotor balance output •

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• Six component tail rotor output :i_

• Torque cell output i_

• Main and tail rotor RPM

!_! • Tail rotor collective position !

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• Main rotor collective and cyclic control positions in

the shaft axis system

• Transmission oil pressure and drive motor temperatures •

• NEFF System 620 status information

When the system is in on-line monitoring mode, each of the above

parameters is sampled once, converted into engineering units and

displayed on the system CRT. Update time fOE this mode is under |i

two seconds. The NEFF system is equipped with 1 HZ filter networks which attenuate all but the quasi-steady state loads. This

mode is used to facilitate each data point set up conditions and

provides general system monitoring. '

When the system is in the data acquisition mode, all the strain

gauge parameters are sampled 10 times and alegabraically averaged.

The other parameters, being steady state values, are only sampled

once. The averaged raw data is recorded on digital tape then

processed into engineering values and output on the computer's

integral printer. The update time of this mode is approximately

40 seconds. During this time, the CRT display is frozen. The

averaging of I0 samples plus the NEFF 1 HZ filtering handles any

non-steady state component in the strain guage loads.

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,__ t At the completion of each run the data recorded on tape were

_i reprocessed to include the start and end zero's as well as being

!I corrected for any significant variations in input parameters, such

:_ . as ambient conditions. Many of the rotor parameters were then . processed further into nondimensional forms (the definitions of.-

_D which are presented in the List of Symbols).

+ " The important main and tail rotor parameters can be plotted

iT ' against each other directly using the HP computer. Currently i

_:_ included are main rotor C+/sigma and C,/sigma against collective,

main rotor C../sigma against C,/sigma, _ain rotor Figure of Merit 

i_ against C_/si_ma (full and exp_nded scale) and tail rotor C_/sigma

_I_ " against C_sigma. _ i

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-_r Examples of .th.ese plots for .a typical test configuration (S-76

Main Rotor wlth 60yo tapered tlps and tractor tail rotor, OGE and . I

a_e = s0h.55) own oare n thepremesented plots in. withFigures a least3-6.square Thes actual curve data fit ropuotints ine

giving a line through the data for all plots except those in-

-7_s volvlng main rotor collective. The curve flt equations for each I

test condition, together with the standard deviation and mean

error, are given at the top of the appropriate tables in the data

_i package of Volume II. '

The bulk of the computer plotted results presented in t_is report i

involve comparison between rotor performance levels as a result of

_I configuration or operating condition changes. These plots entail

two or more curves taken from separate data runs and do not

include the actual data points. The lines represent the least I

_I squares best curve fit.

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i ii Model Rotors Blades and Tips Y

Two sets of main rotor blades were used in the test. The S-70

BLACK HAWK and S-76 blade sets are dynamically scaled versions of

o the actual aircraft rotor blades. The aerodynamic geometries of

o. these rotors are shown in Figures 7 and 8. The two rotor sets

_ were tested with a number of different geometry tips.

'.: j

_ The S-70 BLACK HAWK blades are 1/5.727 scale with a -16 ° equiva-

_'! lent linear twist and utilize the SCi095 and SCi094 R8 airfoil

' sections. They have a radius of 1.428m (56.224 inches), a chord

_ _ of 0.0906m (3.566 inches) and a solidity of .0815. The S-70 "

i_i blades were tested with the 20 ° swept tip of the baseline UH-60A

L _ as well as with a 20 °, 35 ° double swept tip which incorporates a

___ 60_ taper and with a 20 °, 35 ° double swept tip with 20 ° anhedral.

=*:; These tips were 6y. of the blade's radius, and are shown in Figure

_ 9. The three tips were tested alone and the double swept tip and

_;i double swept tip with anhedral were also tested with the tail

__; rotor, i

_'*_ The S-76 blades are 1/4.71 scale and possess a -I0 ° linear twist

Ii_i. and a solidity of .0704. These blades have a radius of 1.423m

_i (56.04 in.), a chord of .0787m (3.1 in.) and use the .SCI09.5 and

_!_ SCI094 R8 airfoils. The S-76 blades were testedwith f_ve dlffer-

_ ent tips, each of 5_ of the radius. The tips are rectangular, 20 ° _ i

!i! s.ept, 60 ° tapered, 35 ° swept- with 60_ taper, and 35 ° swept with

==_ 60_ taper and a 20 ° anhedral. The tips are also shown in Figure I

_. 9. The five tips were tested alone and the 60_ tapered, 35 ° swept

_," with 60X taper and 35 ° swept with 60yo taper and 20 ° anhedral were

\,

!, tested with the tail rotor.

The tail rotor used for this test is non-scaled dynamically and [,

aerodynamically, and has a radius of .2921m .(11.5 inches) and a I

solidity of .2214. It employs four blades wlth _° linear twist ,

,* and an NACA 0012 airfoil section. The ta._.lrotor is located at

_. the scal_ BLACK HAWK locations, without cant, with the option of

_ operating in the pusher or tractor mode. In both cases the tail

' rotor rotation is maintained with the lower blade travelling

forward. The details of the main and tail rotor blades are

presented in Table 2.

The S-70 BLACK HAWK and S-76 blades were mounted with extenders.

This was done to simulate the actual main rotor/tail rotor clearance of the BLACK HAWK helicopter. Details of the clearance,

separation and blockages experienced are presented in Table 2.

:-:,o
Test Procedures

i The test _ns were carried out using a basic procedure. This

. procedure was only modified for _ose r_s involving.__multaneous ,

operation of main and tail rotors.

Following _e preparation of _e model configuration, _e pretest

• calibrations were perfo_ned. The model was _en exercised over

• the full test range of _st values (to min_Jnize residual "stiction"_ and start zeros were taken. The first test data point ,i

taken _as always a "dlm_ic zero". For main or tail rotor alone, ,

_ese operations correspond to a near zero _st condition at _e

• re_ired tip Mach n_er. The "dynamic zero" data point se_es as I

an initial check of _e system, a condition during which blade

flapping can be set to zero and a low _st test point which

helps to ensure a good _ta cu_e fit _oughout _e _st r_ge. _,

i ;

-I.. _en operating bo_ _e main and tail rotors, _e main rotor was

set to _e s_e near zero _st condition wi_ _e tail rotor W

_st adjusted to produce a tail yawing moment equal and opposite

to _e yawing moment produced by _e main rotor torque. The main '_

and tail rotor balance loads were monitored and continually

updated wi_ _e on-line display of _e computer CRT. These data

were used to insure correct main and tail rotor _st settings.

l

( The sequence of events used to take a test point involved initially setting _e main or tail rotor collective and _en adjusting _e _M to achieve _e desired Mach n_er. If _e main and

tail rotor were operating simultaneously, it was next required to

readjust _e tail rotor collective so _at _e yawing moment

produced by _e tail rotor _st balanced _e main rotor torque

wi_in 2_ of _e maximmn torque value.

Following _e "dynamic zero" data point, test points were taken at

2° collective increase steps to approximately 60_ of _e maxim_

collective for _at _n. From _is point +1 ° collective inte_als

were used for data points up to _e rotor m_im_ collective. The

m_im_ collective Was defined by _e rotor _st limit, main

i rotor torque limit, or main rotor stall.

Data were _en taken wi_ reducing collective at half degree

intervals down to _e lower end of _e range of interest• On-line

monitoring of _e delta allowed any repeat or additional points

• required to be identified and obtained• This sequence of data

• acquisition minimized drive motor and gearbox temperature rise and

was only possible because of minimal data hysteresis apparent in

_e data system.

17

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)
. !

J

i' !

"' Following acquisition of the test data, an end "dynamic zero" was "

._ taken. After RPN shutdowns, the end zeros a_ calibrations were

,_. taken. Each data run was recorded on magnetic tape under its own

identification number for future access, reprocesslng, and/or plot

; generation.

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I

TEST RESULTS AND-DISCUSSIONS

Data Repeatability/Scatter r

( e

During the course of the test, between each mounting of the test

rotors with the many tip configurations, a set of non-scale wide

_, , chord rotor blades were installed and run to check the system

accuracy and rep.eatability. A total of 23 such runs were made on

, these "calibration" blades, out of ground effect, at a tip Math

number of 0.6. After eliminating the known ._estionable runs. (due i

to end zero error or high/gusty wind conditions) the remaining i

. runs showed a data repeatability of .6Yoon Figure of Merit or .4X

on rotor lift at constant power.

Main rotor data scatter was found to be accept;bly, low (as the

typical data runs of Figures 3 6 showed) wlth a typlcal Cq/slgma

standard deviation of .000040.

Isolated BLACK HAWK Main Rotor

, The BLACK HAWK rotor was tested with 3 tip configurations. These

consisted of the baseline UH-60A 20 ° swept tip, the 20/35 ° double

sWept tip and the 20/35 ° double swept tip with 20 ° anhedral, (see

FigUre 9 for configuration details). The 3 tip configurations i

were tested out of ground effect at 3 tlp Mach numbers of 0.55,

! 0.60 and 0.65. plus 2. inground effect tests, at S,]'s of 1_2 and

mode 0.75, l conf at igu a rasingle tions tiptestedMacharenumgbierven ofin 0T.6. able The details i

The trend of out of ground effect rotor Figure of Merit with tip

Mach number for the baseline 20 ° swept tip is presented in Figure

10. The loss in Figure of Merit due to a Mach number increase

from .55 to .65 was found to be .023 at a C+/sigma of .08 This i

Math number trend is very similar to that demonstrated on the full

scale BLACK HAWK rotor on the hover whirl stand. However the full

scale rotor experiences a smaller loss of Figure of Merit o';er the

same Math number r:ange, then the model rotor. The full scale

BLACK HAWK tip Math number is 0.628 at the design 1219m (4000 ft)

350C (95"F) atmospheric condition.

When increased tip sweep and taper is introduced into the tip, as

in the double swept tip, the loss of FigUre of Mez_: due to tip

Math number is significantly reduced (Figure 11), and amounts to a

• Figure of Merit loss of only .013 at a Ct/sigma of .08 for a Math

' number increase from .55 to .65.

Introducing 20 ° anhedral into the double swept tip reduces the

- loss of performance with increasing tip Mach number even more,

(Figure 12). Here the total loss of Figure of Merit over the full

Math number range is only .005 at a Ct/si_ua of .08.

19
This change in Mach number effect is also very apparent when the

benefits of the alternate tip configurations are compared._to the

_I baseline swept tip at fixed Mach number. In Figure 13 the 3 tips

° are compared at fixed out of ground effect, 0.55 tip Mach number "

conditions. At this condition the double swept tip has the lowest

Figure of Merit while t"• do.uble swept with .anhedral tip has the

highest with the anhed,..l tlp having a maximum Figure of Merit

increase of .012 compared to the baseline swept tip. Moving to a

_-_t tip Math number of 0.6, OGE, (Figure 14) the sharp Mach number '

trend on the swept tip now results in the lowest overall perform- ,

ante for this tip with the double swept, anhedral tip now having a

maximum Figure of Merit .025 above that for the swept tip. i

At the highest test tip Math number of 0.65, Figure 15, the double

swept, anhedral .tiP,configuration is still the best and now shows

i_i a Figure of Merit increase of .03 above that for the swept tip.

_i In ground effect at a tip Math numbe_ of 0.6, the tips all show an

increase in Figure of Merit compared to out of ground effect.

Figure 16 shows the results at a _/R of 1.2 and indicates slmllar

i__ trends when compared to OGE. Figure 17 shows the results for a

_ I/R of 0.75 and illustrate that the benefits of the anhedral tip

i_ start to fall off when the ground effect become significant. This

i_ is as might be expected as the concept of the anhedral tip is to

_. push the tip vortex down relative to the following blade. In I I

i__i ground effect the downwash velocities for a given thrust level are

reduced resulting in less clearance between the shed tip vortex

_;_ and the following blade.

i_! The actual thrust augmentation ratios for the 3 tip configurations

_=i as a function of rotor _/R are presented in Figure 18 for a tip I

"_ M.ach Number of 0.6 and a fixed rotor Cq/sigma of .007. Thls i

figure also shows that as the tip vortex strength is reduced by

tapering the tip (as used in the double swept tip) the lower

downwash veloclties in ground effect reduce the followlng blade

._ interference and yield better inground effect augmentation.

Based on these main rotor runs alone, the two tip configurations

: selected for study with the tail rotor operating were the double

swept tip and the double swept tip with anhedral.

Isolated S-76 MaiR Rotor

The S-76 rotor Was tested with 5 tip configurations. These '

consi-sted of the baseline S-76 swept tapered tip, a rectangular

tip, a tapered tip with 60_ tip chord, a swept tip and a swept

tapered tip with 20 ° anhedral. The latter tip was specially

fabricated for this test. All other tips, including those used on

, the BLACK HAWK rotor were already in existence, having been

-i previously fabricated under Sikorsky Aircraft IR&D funding. These

_

i_ 20

"t
tips are shown in Figure 9. As with the BLACK HAWK rotor, all

tips were tested at 3 tip Math numbers OGE, and 2 IGE conditionB

at 1 tip Mach number.

The out of ground effect rotor Figure of Merit trend with tip Mach

number for the rectangular tips is presented as Figure 19. The

'_i data at the lowest tip Math number of 0-.55 appear slightly low,

ii " especially at the lower C_/sigmas. None the less, the loss in

.i_ , Figure of Merit due to a tZp Mach number increase from .55 to .65

was still tested as .031 at a Ct/sigma of .085.

_ii!'_ . The use of taper on the unswept blade tip, as shown in Figure 20,

_i reveals a. ve.ry similar loss of Figure of Merit of .032 with

_, increase zn t_p Mach number. However, this value was obtained at

!_, th_lsaowerserle_sCt/runs. sigmaeol.f08, as the data test range was lower during

' l

If a sweep of 20 ° is inuorporated in the tip, the effects of k

increasing the t_p Mach number are significantly reduced as shown

in Figure 21. Again, _he lowest Math number data appears slightly

low, especially at the lowest thrust levels. The tested loss of i

- Figure of Merit at a C_/sigma of .085 was .014.. Introducing taper

! to the swept tips_ Increases this Fzgure of--_rlt loss sl_ghtly to

.018 at the same C_/sigma of .085 (Figure 22}. With the added

_-_ure of 20" anhed_al, the loss of Figure of Merit drops slightly to .01____66 at a Ct/sigma of .085 (Figure 23).

_I Of the tips tested on both rotors the two tips which are the

_;_ closest geometrically are the two 20 ° swept tips. Cnmparisons

_etween the OGE performances of the two rotors (Figures i0 and 21)

show that the BLACK HAWK rotor has approximately .02 higher peak

_ Fi_Ire of Merit at a tip Mach number of 0.6 than _he S-76 rotor. I

:!i)',_ From these S-76 rotor trends we find that taper does not signifi- i

,/: cantly improve the Mach number characteristics of the rotor, tip

.... sweep does and anhedral has a minor impact. This contrasts with

_ the BLACK HAWK results where both taper and anhedral had a beneficial impact. This resu!', is not surprising since the higher tip

_ angles of attack on io',-,:wl_t rotors should be less accommodating

to the further increase .Ln t-_p angle forced by taper. In fact,

,; tip taper will be cffectlve in improving rotor performance only

when the tip o.perateQ w_ll below drag divergence conditions.

Likewise, sweep _s more effective on low twist rotors due to high

" tip loading and accompanying Mach penalties. b

When all .5 tips are compared to each other under the same operat-

/ Ing condltlons, the relative merits of each of the tips are

apparent. Figure 24 presents the results for all of the S-76

,T_ tips, out of ground effect, at a tip Math number of 0.55. The

( lowest performance tip throughout the thrust range Is the rectan-

" gular tip. Introducing 20 ° of sweep increases the performance

¢;

,i 21

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_, ........................................................................................ ,_ _....................................V_
i !

i

slightly - more so at the higher thrust levels. If the tip is

kept straight but taper is incorporated, significant performance

benefits at the lower thrust levels result with less advantage

apparent at the higher thrust levels. The combination of sweep

and taper provides the same improved Figure of Merit throughout

the thrust range that taper alone gives at the lower thrust

levels. Finally, introducing annedral to the swept tapered tip

bumps performance up yet further throughout the thrust range. The

total Figure of Merit increase posslble when progresslng from a

rectangular tip to a swept tapered tip with anhedral at a Ct/sigma

of 0.095 is .041 or 6_ at a tip Nach number of 0.55.

When the results are compared at the higher tip Mach number of 0.6

(Figure 25), the previous trends are all still apparent with the

total Figure of Merit increase possible now up _o .045 at the

lower Ct/sigma of .09. il

At the highest test tip Mach number of 0.65 (Figure 26) the ,

previous general trends still hold; only now the unswept tips are

starting to pay more of a penalty so that at the highest thrust i_q

levels the swept tip shows a much larger improvement over the

rectangnlar tip than before and the straight tapered tip now g_ves

lower performance than the swept tip at the higher thrust levels.

The total Figure of Merit increase recorded has now risen to .057 0

or 8.8_, at a Cg/sigma of .0875. _ .

Figure 27 compares the relative results for the 5 tips at a tip i

- Mach number of 0.6 when operating in ground effect at a B/R of

1.2. The general trend of configuration change effects is very

similar to that shown OGE (Figure 25) except, as with the BLACK

HAWK rotor, the anhedral tip does not improve as much when in _i_'

ground effect as the other tips.

Moving into ground effect further to a B/R of .75 (Figure 28): the

anhedral tlp loses a llttle more of its advantage. At the hlgher

thrust levels, under these operating condit-ions, the rectangular

tip, tapered tip and swept tip all possess similar performance.

If the performance levels of the two rotors with the comparable

20 ° swept tip are compared (Figures 17 and 28) at a tip Maeh

Number of 0.6 and a Z/R of 0.75, the OGE performance advantage of

the BLACK HAWK rotor over the S-76 rotor has now virtually disappeared at the higher thrust levels, although a small advantage

still exists at the lower thrust levels.

The actual thrust augmentation ratio for the 5 tip configurations

as a function of rotor B/R is presented in Figure 29 for a tip

Mach number of 0.6 and a fixed rotor Cq/sigma of .007. Th._.s

f_gure conflrms and quantifies the loss of ground effect augmentation at both B/R conditions as a result of using the anhedral tip

compared to the other tips. Also shown is a loss of augmentation

22

]
i.." I at the high B/R when using the m_ept tapered tip. These results

.: are both consistent with the BLACK HAWK trends with tip geometry

"i (Figure 18) although in all cases the magnitude of the augments-

• tions inVolved are almost twice as much for the S-76 rotor

iiI ' compared to the BLACK HA_I(. This result is consistent with the

; findings of the _revious study [Reference (I)] which showed that

..:?_ higher twist rotors have lower thrust augmentation capabilities.

• ! |

_,.!.. With the systematic Variation in rotor tip configurations under-

!:it taken in this test, the il_cremental influence of each tip change

on the rotor figure of merit experienced has been determined and

"" is presented in Table 3 for a constant rotor Ct/sigma of 085 for

- an OGE tip Math number of 0 6. From this we can see that tip

•,_ taper an.d sweep _ave comparable effect, and adding taper to a

. :: .swept tlp or sweep to a tapered tzp have comparable results• The

""-i increases _.n figure of merit on the hlgh twlst BLACK HAWK rotor

_'_I were lower than on the S-76 rotor. _

i! From these results the primary -.hoices for the follow on testing w

with tail rotor are the a_edral tip and swept tapered tips. ! I

• However, these 2 configurations Were else, _elected for the testing

with the BLACK HAWK rotor and the duplication was not considered

i_ appropriate. From the BLACK HAWK series, the effects of anhedral

ilil could be assessed and which if then applied to the S-76 series of

-"i!i tests would not require the swept taperect tip tests• For this reason the second tip selected for re,sting on the S-76 rotor was

the tapered tip.

_:

The S-76 rotor with the swept tapered tips Was also tested in

"::_ this phase as additional runs not required in the original con-

_: tract Statement of Work• Unfortunately not all test variables

_ were possible due to time constraints, with the result that only

" those runs involving the pusher tail rotor configuration were

_: completed

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--"-1"
--' BLACK HAWK Main Rotor with Tail Rotor )

_- As indicated previously_ four tip configuration were tested in the

presence of a tall rotor, with the tail roto_ in both pusher and '

- tractor configurations. Three runs were made out of ground effect

with tip Math numbers of 0.55, 0.6 and 0.65 plus two in-ground

- effect runs at Z/R'8 of 1.2 and 0.75 at a tip Math number of 0.6. ,

_. The two tip configurations tested on the BLACK HAWK rotor were tI',e

:. double swept tip and double swept tip with anhedral, while the 2

" tip configurations tested on the S-76 rotor were the 60_ tapered

! tip and the swept tapered tip with anhedral, (plus the limited

.. runs on the swept tapered tip).

_i_' The impact of the tail rotor, both pusher and tractor, on the out

_ of ground effect hover figure of merit of the BLACK HAWK rotor

! with the double swept _ips operating with a tip Math number of

":_i 0.55 is shown in Figure 30. The operating tail rotor has a

i_ similar impact on r_duclng the maln rotor performance zn ezther

,_ the pusher or tractor mode. At representative thrust levels this

:':' loss of performance is approximately a 1.2Yo loss of thrust at

!i!' constant power.

/ However the results with the same rotor and tip configuration at a i

_- tip Math number of 0.6 (Figure 31) shows that the tractor tail

:_ rotor imposes a smaller penalty on the main rotor performance than i

_- the pusher t_11 rotor but the actual penalty for the tractor Is k

still higher. than at the lower tip Mach number. The tail i

tractor

rotor penalty was found to be 1.7_ loss of thrust while the pusher r']

penalty was as high as 3.1_.

. Similarly at a tip Math number of 0.65 (Figure 32) the tractor

.... t

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ai

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the

otor

pusher

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tail

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wer

otor.

perf

The

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losses

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measured

e main ro

wi

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th

an

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operating configuration were a 1.5_ loss with the tractor tail

j: rotor and a 2.5Yo loss with the pusher tail rotor.

_ When the BLACK HAWK tips are changed to incorporate anhedral the

..... impact of the tall rotor on the main rotor performance was very

similar to that discussed above. At the low Math number of 0.55

- (Figure 33), the 2 tail rotor modes of operation have essentially

identical impact on the main rotor performance - a lo_s of ap-

__:. proximately 1 • 7_ 2n thrust for both • At the two higher Mach

numbers of 0.6 and 0.65 (Figures 34 and 35 respectively) the

tractor tail rotor causes a lower thrust loss than the pusher tail

rotor with both losses being more than either caused at the lower

tip Math number. The actual losses of main rotor thrust as a

function of the tip configuration, tip Math number and tail rotor

operating mode are presented in Table 4. As indicated, when a

tail rotor is operating close to an advanced geometry tip on an

_:- BLACK HAWK rotor the rotor will experience a thrust loss averaging

_. 24
I

¢

2_5_ which is 0.6X higher than that eKperienced with less advanced

tip configurations.

. Operating the BLACK HAWK rotor with the double swept tips inground

effect, at a tip math number cf O.6, retains most of the OGE

trends, wlth just a small reductlon in the thrust loss experlenced

• by the main rotor. When in ground effect at a Z/R of 1.2 (Figure

: 36) or 0.75 (Figure 37) the main rotor T/_rust loss when the tail

• rotor is o.perat%ng in the pusher mode is always more than when

operating In T/:e tractor mode. In fact at the lower thrust '

levels, when operating the tail rotor in the tractor mode, the ,

main rotor can even experience a thrust gain compared to isolated

rotor. The further in ground effect the main rotor is operating,

the larger this thrust gain becomes. This low thrust level

performance increase was not seen on the S-76 rotor or in the

previous test (Reference I) and is probably the result of the high _

BLACK HAWK rotor twist plus tip configuration combination. The i

r treIld due to both components is in this direction. !

i_ The addition of anhedral to the tip configuration, resulted in the !i

isolated BLACK HAWK main rotor trends in ground effect changing

_ significantly. Similarly when the BLACK HAWK rotor with the

double swept tips with anhedral is operated in ground effect, in

i the presence of a tail rotor, the trends are changed. At a Z/R of

1.2 (Figure 38) and a Z/R of 0.75 (Figures 39) the results have a

_ , similarity to the OGE results of Figure 34, showing a variation

- with the mode of tail rotor operation. However unlike the double

swept tip, no significant reduction in the interference seen by

the main rotor due to the operation of the tail rotor is apparent

when moving into ground effect. This trend further errodes the i

benefits to be gained IGE from the use of anhedral tips. A quick ,

comparison between the tail rotor operating 1GE performance for J'

the double swept tips (Figure 37) and the comparable performance i'I

with the anhedral tips (Figure 39) shows this clearly.

The actual losses of main rotor thrust as a function of the tip

configuration, Z/R and tail rotor operating mode are presented in

Table 5.

S-76 Main Rotor with Tail Rotor

The first tip tested on the S-76 rotor with the tail rotoz- operating was the 60_ tapered tip. Figure 40 shows the OGE impact of

- the tail rotor, tractor and pusher, at a tip Math number of 0.55.

A small impact of tail rotor operating mode is evident (the

tractor tall rotor this time _howing the highest interference by a

small amount). A tip Mach number of 0.6 (Fi.gure 41) causes the

hlghest interference for both modes. At the h_ghest Math number

of 0.65 (Figure 42) the trends are again very similar with less

sensitivity to the tail rotor operating mode but the same level of

i

i 2s
overall interference as experienced at the lower Mach number. The

magnitudes of the thrust losses are presented in Table 4.

When the tapered tip on the S-76 had sweep and anhedral introduc- " _

ed, for all of the OGE conditions (3 Mach numbers of 0.55-Figure

43, 0.6-Figure 44, and 0.65-FigUre 45), the mode of tail rotor

operation had minimal effect on the interference measured on the

main rotor. Also, the magnitude of the interference was reduced

compared to the tapered tip. The magnitude of interference was

' reduced from an average of approximately 2.3Y. for the tapered tip

to approximately 1.5_ for the swept, tapered tip with anhedral.

Figures 46, 47 and 48 show the OGE results for the swept tapered

tip configuration at tip Mach numbers of 0.35, 0.6 and 0.65

respectively with the tail rotor operating only in the pusher

_ mode. A consistent, approximately 1.7_ loss of main rotor tl_vust

was recorded due to the use of the pusher tail rotor. This thrust

t loss is very comparable to that recorded with the swept tapered

I anhedral tips (1.6_) and less than measured with the 60_ tapered !

1 tips (2.2_) when operating with a pusher tail rotor. These

I results are all presented in Table 4.

Switching back to the 60_ tapered tips and moving into ground

effect, at a Z/R of 1.2, Figure 49, the mode of operation effect

for tail rotor, just as for OGE, was found to be small. However _

at the lowest Z/R of 0.75, Figure 50, the tractor tail rotor -,-

produced more main rotor interference. The overall effect of i

moving into ground effect, as with the double swept tip on the _

BLACK HAWK rotor, was to reduce the interference seen by the main

rotor by approximately lYo. i

For the S-76 rotor with the swept tapered tips with anhedral, _'

moving into ground effect provided conflicting trends. At a Z/R

of 1.2 (Figure 51), the tractor tail rotor results indicated no

interference effects, will normal (sligh_oy less than OGE) interference with the pusher tail rotor. At a Z/R of 0.75 (Figure 52),

the tail rotor modes produced similar interferences. Overall the

effect of moving IGE was to reduce the interference by approximately 0.6Yo.

Unfortunately, the IGE testing with the swept tapered tip on the

S-76 was not completed but did show (Figure 53), at a Z/R of 1.2,

a significant reduction of interference felt by the main rotor due

to the tail rotor presence.

The full tabulation of the main rotor interferences measured with

the tail rotor operating as a function of main rotor, tip geometry, tip Mach number and tail rotor operating mode is presented

for OGE conditions in Table 4 and for IGE conditio_m in Table 5.

I

26
.:) t

i

_ ,i From these results a comparison can be made between the perform-

'!I ance improvements to be had from the use of advanced geometry tip

,"i configurations when tested under main rotor only and main rotor

;i . with tail rotor conditions. Figure 54 presents such a comparison

_. and...shows .a plot. of the percentage performance improvements

•i avallaDle wnen uslng 4 alternate tip configurations when. tes.ted

_f alone an.d In the presence of a tail rotor. The 4 tips shown are

:-_ ' _ne aouDle swept t_ps and double swept tips with anhedral used on

!:! . the BLACK HAWK rotor and the 60_ tapered tips and swept tapered

' tips with anhedral used on the S-76 rotor. The performance

i''::i: improvements quoted use the baseline tips appropriate to each of

the rotors, that is the 20 ° swept tip on the BLACK HAWK rotor and

':ii " the swept tapered tip on the S-76 rotor. The 45 ° line represents

'__ the situation where the performance improvements measUred rotor

•._ alone are exactly maintained when operating with the tail rotor.

_ ,, The results from this test being very close to the 45 ° line show

iii that the tail rotor influence does not significantly change the

i benefits to be derived from the use of the advanced geometry tip

!!i! configurations tested, when compared in. the benefits measured by

main rotor alone testing.

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i_-i 27

i '
CONCLUS IONS

Main Rotor Alone

• The higher twist BLACK HAWK rotor (with baseline swept tips)

has higher OGE performance than the S-76 rotor (with baseline

swept tapered tips ).

• The high twist BLACK HAWK rotor experiences less thrust

augmentation IGE than the S-76 rotor. In fact, the peak IGE

figure of merit of the S-76 rotor with the 20 ° swept tips at

a Z/R of 0.75 is the same as that for the BLACK HAWK rotor

with 20 ° swept tips.

• Introducing taper (via the double sweep feature) and then .

anhedral on the BLACK HAWK rotor progressively reduced the i

sensitivity of the rotor to tip Mach number for OGE conditions. Except at the lowest test tip Math number, the above _

changes also give the rotor progressive increases in figure

of merit, resulting in the double swept tip with anhedral

having a 6.7_ increase in peak figure of merit over the

baseline tip, at the highest test tip Mach number 0.65.

'L

• Moving the BLACK HAWK rotor into ground effect with the

alternate tip configurations shows that the ground effect _ ;

augmentation reduces progressively with the introduction of

taper and anhedral. However, the out of ground effect advantages of the tip changes are such as to still give a per- i

formance advantage of the new tips in ground effect.

j, _J

• The S-76 rotor tip configuration with the greatest OGE _

sensitivity to tip Mach number was the 60_ tapered tip i

followed by the rectangular tips swept tapered tip, swept tip

and swept tapered tip with anhedral.

• The S-76 tip configuration with the lowest OGE peak figure of

merit (at a tip Math number of 0.60) was the rectangular tip,

followed by the 60_to tapered tip, swept tip, swept tapered tip

and swept tapered tip with anhedral. However at lower thrust

levels, the 60_ tapered tip performance was second only to

the swept tapered tip with anhedral.

• Moving the S-76 rotor into ground effect with the alternate

dent ip czconfi al guthrus ratiotns aureveals gmentatlo.3n oftrends the .tiP_h;ive3essentia tips,llythe

rectangular, tapered and swept, also have the lowest OGE peak

figure of merit. The swept tapered and swept tapered with

anhedral tips have lower thrust auqmentation, but still

superior figures of merit relative to the other 3 tips.

28
• • .

Main Rotor Plus Tail Rotor

• Operating in the presence of the tail rotor, out of ground

• effect, the BLACK HAWK anhedral tip configuration showed a

slightly greater average thrust reduction (2.5_) than the

double swept tips without anhedral (l.9Yo). The S-76 anhedral

i tip however, showed no thrust reduction relative to the swept

t ' tapered tip and less reduction (1.4Yo) than the tapered tip

• (2.4X)•

• in ground effect, the average thrust reductions due to the

tail rotor presence were unchanged or lower, for the rotor

•_, " tip configurations tested.

• The thrust reductions due to the tail rotor generally increased with increasing main rotor tip Mach number but not in

all cases or by the same magnitude.

h • Out of ground effect, the BLACK HAWK rotor with double swept

tips and double swept tips with anhedral showed an average

2.7_ thrust reduction with the tail rotor operating in the

-_ pusher mode and a 2.2._ reduction with the tail rotor operat-

) ing in the tractor mode. The S-76 rotor tip configurations

did not show any clear sensitivity to the tail rotor operat-

"° _i ing mode •

_ • In ground effect, the greater sensitivity to the pusher

_.i configuration was still evident for the BLACK HAWK double

swept tip but the double swept tip with anhedral configuration did not show the same sensitivity to tail rotor mode of

operation•

• Overall the data implies that the tail rotor effects on the

advanced tip configurations tested are not substantially

different from the effects on conventional tips• Therefore

the majority of the benefits obtained from advanced tips

should be retained.

- ¢

I

+

p I

_.:!. 29

l,
t

i

/," REFERENCES "

1. Balch, D. T., Saccullo, A. and Sheehy, T. W., "An Experimental Study of Main Rotor/Tail Rotor/Airframe Interactions in

: Hover," NASA-CR-166485, June 1983 •

: 2• Menger, R. P , Wood, T• L and Brieger, J T•, "Effects of '

Aerodynamic Interaction between Main and Tail Rotors on

- Helicopter Hover Performance and Noise", NASA CR-166477,

_: February 1983.

_: 3. Philippe, .J..J. and Chattot, J. J., ".Experimental and Theoretlcal Studles on Hellcopter Blade Tips at ONERA", Paper No.

; 46, 6th European Rotorcraft and Powered Lift Aircraft Forum,

_.:' 1980.

_-_: 4. Tauber, M. E., Change, I. C., Caughey, D. and Philippe,

. J.J., "Comparzson of Measured and Calculated Pressures on t

_il Straight-and Swept-Tip Model Rotor Blade", NASA TN-XX,_X,

'" 1983.

'i "Aerodynamic Design of . :_l 5. Philippe, J. J. and Vuillet, A.,

:_::: AdVanced Rotors With New Tip Shapes", 39th Annual Forum of

•' the American Helicopter Society, St. Louis, Missouri, 1983. ;

I

,!_ 6. McVeigh, M. A., McHugh, F. 3., "Recent Advances in Rotor

_ Technology at Boeing Vert,_l", Paper No. 82-38, American

_. Helicopter Society 38th Annual Forum, Anaheim, California,

_ May 1982•

7. Wilby, P. G. and Philippe, j. J., ,,An Investigation of the |

" Aerodynamics of an RAE Swept Tip Using a Model Rotor", Paper

_" No. 2.5, Eight European Rotorcraft Forum, Aix-en-Provence, I

. France, September 1982.

_/_ 8. Caradonna, F. X. and Tung, C., "Experimental and Analytical

Studies of a Model Helicopter Rotor in Hover", NASA TM 81232,

ii, September 1981•

: 9. Caradonna, F. X. and Philippe, J. J., "The Flow over a

: Helicopter Blade Tip in the Transonic Regime", Paper No. 21,

_- Second European Rotorcraft Forum, Buck,burg, West Germany,

" September 1976

L i0. Chattot, J. J., "Calculation of Three-Dimensional Unsteady

Transonic Flows Past Helicopter Blades", NASA Tech Paper 1721

October 1980.

)

i

t. ,

I

"_ 30

i,
_ REFERENCES (Cont' d)

11. Grant, J., "The Prediction of Supercrit_cal Pressure Distributions on Blade Tips of Arbitrary Shape over a Range of .

• Advancing Blade Azimuth Angles", Vertica, 1979, Volume 3,

Numbers 3/4 pp 275-292.

• 12. Ballard, J. D., Orloff, K. K., and Luebs, A. B., "Effect of

• Tip Planform on Blade Loading Characteristics for a TwoBladed Rotor in Hover", NASA TM 78615, November 1979. ,

13. Philippe, J. J., Lafon, P. and Bohl, J. C., "Experimental

• Studies of Unsteady Aerodynamics of Helicopter Rotor Models

in a Wind Tunnel", Aeronautical and Astronautical Association

of France, TN 79-21, November 1978.

14. Stroub, R. H., "Full-Scale Wind Tunnel Test of a Modern ' _

_ Helicopter Main Rotor-Investigation of Tip Mach Number i

r_ Effects and Comparions of Four Tip Shapes", Paper No. 03,

American Helicopter Society 34th Annual Forum, Washington, D.

i C., May 1978. _

_

4

|

31
'i

-')I '_ TABLE

1.TEST CONFIGURATIONS

:_ 32 I' t .;

)

G' -'+ ';>
I

_ o _ , _

o

r_

*_--I _ I_ "_ _3 1 0 _

O_

"_1 _1 0 _1_-.'

i: I TABLE 2. MODEL ROTOR CHARACTERISTICS

: 33
I

!

t

ROTOR CT/SIGMA = .085 OGE MT ffi0.6

Fiqure of Merit Increase

Configuration Chanqe BLACK HAWK S-76

* 60_ Taper on Rect. Tip .0070 _1

20 ° Sweep on Rect. Tip .0071

,i

Sweep on Tapered Tip .0118 

_i 60_ Taper on Swept Tip .0065 .0117

;_;i Anhedral on Swept and .0201 .0277 i1

_.] Tapered T_p

12;r

TABLE 3. MAIN ROTOR ALONE - PERFORMANCE INCREASES

i

.!

t
m _!

_i_' ( TABLE 4. Yo LOSS OF MAIN ROTOR THRUST DUE TO ADDITION OF TAIL ROTOR

•i! 3_

ii '
• !

TABLE 5. _ LOSS OF MAIN ROTOR THRUST DUE TO ADDITION OF

TAIL ROTOR

;:i 36

Ij
,-.,, _ t,l_Tol_ll'_L F/, .IL..'

IRLACKAI_.;f__'_'HITEI-_HO-I-OQRApH

e

o

I

-:" 37

;t-

'1


oEpOOR_.IAU_.

)

Thi.._. Data Re¢orded,Processed_.and Printed Uttltz|ng

MODEL ROTOF.:ON-LIHE DRTR RECORDING RND PROCES$IHG SYSTEM

Pun#- 138.88 z/r= 3.88 Main Tip Math # - .55 Ta_l Tip Mach# ,, .55 "

Test Date :4 RPRIL 1983

Test Summary :S-?G w/ GO_, TAPER/ TRRCTOR TRIL ROTOR

CONFIGURATION FILE : I)RTRI8 8?6[ll]wEXT/wTail/New Torque

I)flTR FILE : TIP138:T14

FUSELRGE NOT PRESENT

Processing B&te :? NOVEMBER 1983

Process Summ_'y :FINRL PROCESSING

Ft_ure Of" Merit us Ct/St_m& i:

*)

f *'1

!

0 x i _

: [

b. / i

) ! !

. i I

. m2 •_4 . ;_6 • _8

Ct/S igm_

m

Figure 4. Typical Main Rotor Full RangeFigure of Merit - Ct/sigma Relationship _ )

4O

!

)>
IIi

' ORIGINAL:PAGEIt

t,

OEPOORt_IALI'I'_ "_

Th i ;_ D._t _, R¢.,:,:,r.de,:l, Pr'oc e;_z.ed _.Lr,::l Pr' i n*. ed IJr i I t z i ng

t40[_ELROTOR ON-LIHE DRTR RECORDIHG RND PROCE$SIHG SYSTEM

P,.m_= I_:'_,_'_ =.r" 3.00 r1_in Tip Mach # = .55 Tall Tip M_ch # " ,55

T4-_,..D.a_e :4 APRIL 19e'.3

Te_t :Summ._r_ :$-7_ w/ 68_; TRPER/ TRRCTOR TRIL ROTOR

' COHFIGURRTIOH FILE : DRTflle S?6[ZI]wEXT/uTa|l/Hew Torque

:, - DRTR FILE : TIP13S:T14

FUSELRGE NOT PRESENT

Processing Date :? NOVEMBER 1983

Process Summary :FINRL PROCESSIHG

• Figure or Mert_ uS Ct/S|_m&

.to

L

", .?5

©

L

.65

.6

Ct/Sigm

Figure5. TypicalMainRotorExpandedScaleFigureof Merit- Ct/sigmaRelationship

-:" 41

!

' I

• pirate01' oF gammuo OOqI'I5

J

Figure7. BLACKHAWKRotorGeometry

• I

I 43
Figure 8. S-76 Rotor Geometry

-. ;+ !

::! 44

"1

;1
i.-t

,9 . t

:' , •

o_

O

UH-6OA BLACK HAWK ROTOR TIPS

i., t t

"_t 6 %SWEPT TIP IS) 6%DOUBLE SWEPT TAPERED 6% DOUBLE SWEPT }ii BASELINE UH-60A MINi-ANHEDRAL (DSTA) TAPERED TIP (DsT)

S.--76 ROTOR TIPS,

t_ SWEPT TAPERED TIP (ST) TAPERED TiP (T) i '

C

_' SWEPT TAPERED

. RECTANGULAR TIP (R) ANHEDRAL TIP (STA) #

....: SWEPT TIP (S)

r

5% TIPS

,,_! Ftgure 9. Ttp Conflgur'attons Tested

::i 45
'J 'Ii

i

i

This Data Re¢orded,Proceisedp&nd Printed Utilizing

HP9945B/SERlES 4GSe MflGNETIC TRPE DflTfl PROCESSING SYSTEM

PLOT SERIES : $-?e BLRCKHRNK Pit TREND; OGE; 28 Dog SWEPT TZPS

Ft 1elf Ft 1e-Name lot_... P _ Plot-Tt t, le

2G TlPO66 ! Ht," 0.68

2? TZPO61 2 HI;- 8.65

28 TIPO62 3 Ht- O.SS t

t;

F|gure otP Hert_ us Ct/Stgmt

.85 ..............................................................................................................

i_ ,

*fern

_ e5 ! I................ I - ............

_ :::::c -

.$5

.OS .08 .07 .Ot .09 • I . I !

Ct/S iclma.

Figure IO.

4.6
F

This l)&ti Recorded,Precessed,ind Pr4nt.ed Uttltz_ng

_, HPg@45]I/SERIE$ 468e MflGHETIC TAPE DflTI:I PROCESSING SYSTEM

"_; f

PLOT SERIES : $-?8 ILP,CKHflHK Ht TREHZ); OGE; 28 Deg/ 35 ])eg DOUBLE $NEPT TXP$

i" Ftle# Ft 1e-N_mqe Plot,# P1ot.-Ti t,I e

' 6 TxPe25 ; I1_.- e. 6e

" _ L " ? TZPC26 2 Ht " g"SS

_ 8 TI pe2? 3 I_t- e.(;5

•;_

Ftgure o¢ Her|_ us Cl_/$tgm&

•85 ..............................................................................................

i

-o'_,_ _._ •f_ "_"_"_,.......................................... , ....................

============

• .55

Y: ! Ftgure 11

"1 47

1 '

', _

2;

i

.,
Tht$ Da_, Record@deProcessed,tnd Prtnted Utt14z4ng

HP?e45B/SERIES 468@ MAGNETIC TRPE DATA PROCESSING SYSTEM

PLOT SERIES : S-?8 |LACKHflMK Mt TRENDS; OGE; 28 Dig/ 35 Deg DOUBLE SWEPT M/

28 Deg AHHEDRRL TIPS

FtlIO Ftle-Hlme Plot# Plot-Title

18 TIPe4S Z Ht-8,65

19 TIPS4? 2 M_-8.68

38 TZ.P846 3 Ht'8.SS

.S5

.OS .08 .e_ .88 .09 .1 .11

Ct/Sigm

Figure 12.

48

1

:_ .t _ ̧

' Thls Data Recor'ded,Processed,_md Prln_.ed Uti1|z4ng

i !: HP9845B/SERIES 4900 HAGHETIC TRPE DI:iTA PROCESSING SYSTEM

_f

; PLOT SERIES : $-?0 BLACKHRXK TIP COMPRRISOH; OGE; MIwO,6

i

:: le..._ F 1 _ F1 le-Hame Pot_.._ 1 _ Plot-TII le

" 6 TIP025 ! 20 Dog/ 35 Beg DOUBLE SXEPT '

_: 19 ?IPQ4? 2 20 Dog/ 35 Dog DOUBLE $XEPT W/ 20 Dog RHHEDRRL

26 TiPO60 3 20 neg SXEPT

_ •

Figure o¢ Herit, vs Ct/Sigmi

:' 85

!

'2

i

! Y'+'; ,_e,,t_,.,,,e,,e_ _._ =============================== _ _

+ 3 "_'

i,

,.., .El .0_ .08 .09 • 1 . ] i

"' CtfSigm

- Figure 14.

.. 50

/.

_. _........................................................................ . ....................... +_--'=,._¢-,_,_._+,
This Data Ro¢orded_Proco$$ed,tnd Printed Utillz_n9

HP984Sa/SERIES 4608 MAGNETIC TAPE DFITR PROC.E.S$I.H.G.S','STErt

PLOT SERIES : $-?e )LRCKHRWK TIP COMPRRIS0N; 0GE; Ht=e.65

F te... 1 _ Ft I e-Name Plo_# Plo_-Ttt lat

, 8 TIPe2? 1 28 Dog/ 35 Dog DOUQL£ SMEPT

18 TIPe45 2 2e =eg/ 35 Deg DOUBLE SHEPT M/ 2e peg RHHE_RRL

2? TZPe6! 3 2e Deg SMEPT

!i

Ftgure of' Herit _$ Ct/Stgm&

u

• • 85 _ --* _ lemmHe@H_t0@tH_*H*_ 1 *_*H 4*_teHIt*e,, )4t,*¢*H_***, **************************** _*e44*_te_ **_etH_,*@ I )_o_ _* ............

• i i

t

!

i

°

e_ .

_......,

0 •?' ........................................ ;=:_ ...............

._..."

"" _'.f i t i

55

• OS .e6 o0_ .e8 ._9 .1 . 1

Ct/S igme

Figure 15.

51

' _ _--:_. _.:_........... -'- =..................................... - ;..................... ";"_,.9" '_'_" a, ...... " " " " _ .........................
:-4"E_'-_+++ ;_,_"'__"

PAQE IS '|

._ OEPOORQUALITY

Th_ D.i_tl R¢,:,or.,=e,_,F'r,_,:¢_s+ed,and Printed Utillzlng

H=li__:_.___/l+_=EPIE_5.46_I_.'t HRGtHETIC TRPE DRTR PRb+'ESSIH__ SySTEII

PLOT :_ERIE_; : $-70 BLRCKHRN_: TIP COMPRRI_OH; IGE; Mr=0.6; Z/R= 1.2

: Fi loll F@... t 1 _._Nam. - _..__i P1.9_il --. Plot-Title -.=--

Xe TIPe29 I 2e Dig/ 3S Deg =OU=L£ SWEPT

[? TXPe43 = 20 =eg/ 35 De_ DOUBLE SNEPT N/ 28 Dig AItHE=RRL

':_ 38 'rzPe66 3 2e |leg SNEPT

• Ftgure o¢ Hert_ us ¢t/Stgma

i

p

i

i

7-

........... _ .................. i .............................................. ! ................................... i

2 : 1

= ............... +I................ _ ....................... +_.......... _................... ! +

• -- I I

: _! i . +

::]+* ,-o --- --_! ................................ 1........ ............ - a l........ iI

++ ! L .?_ ....... ........................ .m.- ................ .................... II

+++ ¢U - _ +

; _r I !

i + +'!

i=_,_ Ill II........................................................................ ! .........................

l

+ ;

t

+ i t +

.S_5 +............................ ---'-- .................... +...................... L+................................... .+
- C'c

/Sigm_

Figure 17.

53

:'+
15,,

i -,_!

" 1.06 I

MT : 0.6

:; I C) 20° SWEPTTIPS '

__ Cq: .0007 r:l DOUBLESWEPTTIPS

J" " _ _ DOUBLESWEP1+

: 1.04 ANHEDRAL TIPS

:i:i 1.03 -,

.... I\\\ , ;

i o-_,_ MRT

',_" t

_LI 1.02 =

! ,2 1.01

! ',

_ i. .

i " _°

L;

,,

,_. 1.1111

i;_ 0 1 2

Z/R

:'3

,. Figure 18. BLACK HAWK Rotor, Ground EffectAugmentation

> ]

;. 54
I!

I

Tht$ l)at& Rocorded_Procqessedtand Printed U;tltztng

HP9845B/SERlES 4(;88 HriGHETZC TriPE DriTri PROCESSIHG $YSTEH

PLOT $ERZES : $-?6 Ht TREHDS; OGE; RECTRHGULriR TZPS

F|le# F|le-H&me Plotgt Plo_-T|_le

21 TZP054 1 H_'g.6e

22 TZPe55 2 M_-e.65

23 TZPe$6 3 H_-8.55

Ftgure o_ Hert_ us Ct/Stgma

• 05 ..............

• 8 ................................................

i

%..

•

.8

.55

. .05 .08 •97 .e8 .29 .1 . ]l

C%/S i gme

Figure 19.

55

I-p

"I1 ' , ,. " .... - --"
i,:: Th|s l)ata RecordedtPr'ocessed_,nd Prtnted Ut|ltz|ng !

:i HP984Bl/SERIES. 46_0 HRGHETIC TAPE ])fLTA PROCES$IHG SYSTEM

4,

,_ PLOT SERIES : S-?6 Mg TREHI)S; OGE; 60_. TAPER TIPS

,:'...

Ft lett Ft 1e-N_e Plot,# Plot-Tt t,le

_.... 33 TIPS?2 ! M_'@. 55

':_" 34 TI PO?3 2 M1;-e. (;e

:' _ 35 TIPS?4 3 M_-O. (;5

_ Ftgure o*" Mertg v$ Cg/Stgm&

_? em

o_.... 85 ...................................

_L."'

_ ° p,,w, _-

23"

:>. Q,) _..- ,............. _,-"'"

;- ............................. .___.----- .2_......... •

• _ ___.,___3 .................................................

" Z ................ ii iiiiiiiiiii-iiiiiiiiiiiii - ;.-12" 

. ,i

i

? .55 " .05 • 08 •O_ • @8 .19 . I . JI

Ct/ igme

" FIgure 20.

, o, 56

- _'_ _,_- ......... _'_' ,,._ ..... :"- - _ .... _-.L.__ ,_ ........ -.. -.. , ,.._ _..,
This g&t& Re¢orded_Processed_and Pr|n_ed U_tl|_tng

HPgS45BISERIES 46so MRGHETIC TAPE DRTR PROCESSIHG SYSTEM

PLOT SERIES : S-?6 M_ TRENDS; OGE; 28 Deg SWEPT TIPS

FtleO File-Name Plo__...._ Plod-Title

' 13 TIPe38 1 Mt=8.G5

14 TIPO39 2 M_-O.GG

15 TZPO40 3 Mt-S.55

Ftgure o_ Mert_ vs Ct/Sigm&

IS_ ........................................

'i

".1

_m_ --_----?_?Liv w=_w :_v w:=_:=i:::_w:_7:::_:_::::7:: ::.,r i :::: ::.: ::_::::: ::::::==;_::_::_:::::;:::::_:::_:=;:=:::::_::::_-::::_:::::::_l

• _1) ............................... :____.:::_:._ ....... .. : ::.:::::.__. _ . .... =============================================================

_..... ,...-- ----- |

2

.55

• E5 .e8 .eP .e8 ._ .1 .11

Ct/ igm

iim

Ftgure 21.

57

i,
Thls Data RecordedmProcessedm&nd Prlnled Utili:Ing

HP9045)/SERIES 4600 MRGHETIC TRP£ DRTR PROCESSING SYSTEH

PLOT SERIES : S-76 He TRENDS; OGE; 20 Deg SWEPT W/ GO_ TRPER TIPS

F(le# File-Hams Plo¢# Plot-Title

1 TIPOI? I M_-0.60

2 TIP818 2 H_se. SS

3 TIPS19 3 HtlO.65

Figure o_' Merit vs C_/Stgma

42 .85 .........................................................................

i:;t

:. .lid

!- : (1_

t

l

g

.05 _,

h ..............

.8

.55

.et .86 .I;P .e8 .oo . 1 • I1

Ct/Sigm

Figure 22.

:'" I

58

, . .................................................................................. _ _ -.:- _ .....................................................
: This Dart Recorded,Processed,and Prtnted U_iltztng

i :0 HPgS45B/SERIES 4688 RRGHETIC TRPE DRTR PROCESSING SYSTEM

PLOT SERIES : S-?6 HI; TREHDS; OGE; 28 Deg SWEPT W/ 68_. TRPER & 28 Deg RNHE_)RRL

TIPS

-, , Ft I e# Ft 1e-H4me P1otl) P1ot-T t t,i •

: 36 TZP8?I ! R_lS. 68

":- ' " 3? TIP@?9 2 M_-8.65

;_ 38 TIPOII 3 M_I8.55

,i;f

:, Flgure o¢ Mertg v$ CglS|gm&

:] I I

?I i'

;I .8 .............................. I

e

,!., _ _...._.

° ""--2 ;IiiiiiiiI ....;iii i

,8

" C'c/S igm_ •

z Figure23.

'1

• 59

:_ .............. _ ...... _.-.-:_-_..._.... __ ._.... ....... _ .............................._ -.
I-_j(-rT__ ''__)____ _'".... : : ._._ (r_ l,

/u

¢

This D.a_.LRecorded,Processed, and Prin&ed U&ili=Ing

HPgS45B/SERIES 4688 MRGNETIC TAPE DATA PROCESSING SYSTEM

PLOT SERIES : S-?6 TIP COHPARISON; OGE; Hem 8.55

Ftle._._._ Ftlt-Hame Plot._i_.#_ Plot-T|tle

2 TIP818 1 28 Deg SWEPT W/ 68_ TAPER

15 TIP848 2 28 Deg SWEPT

, 23 TIP85_ 3 RECTANGULAR

33 TIP8?2 4 68_ TAPER

38 TIP888 5 28 Deg SWEPT W/ 68_ TMPER _ 28 Deg ANHEDRAL

Ftgure or" Merit us Ct/Stgma

i

...............................,......................... t...... *.......................i

•_ ...................... l ""............... 1 *............. .......... I

• r_ . -_. , - ,_

. l ;

_" ................. I..... -----_...S ...................... ...... t.......... )

0 .? .......... L .......... '

S5 _ ....... f:""

°_

b. ................................................ i,........................................ •.............. .............. ,

,

I I

) I

........................ i............................................. :...................... , t.............._-.............F..............t

I

II

._ .............. .............

• _5 .08 ._7 ._8 ._9 • 1 . I 1

Ct/Sigm_

i

, Ftgure 24.

,- 60

-,
Th|s O_t_ Recorded,Processed,and Printed Ul_tllztng

HPgS4513/SERIES 46ee HRGNETIC TRPE DflTfl PROCESSING SYSTEH

_: t

,i

•.... PLOT SERIES : S-76 TIP COHPRRISON; OGE; Pit,- 0.6 , :}

Ftle# F| 1e-N_me Plot# P1 o_-Ti.t, 1•

1 TIPe17 ! 2e Deg S14EPT 14/ 6e_. TRPER

' 14 TIP839 2 2e Deg SMEPT

.! . 21 TIPOS4 3 RECTRNGULRR

34 TIPS?3 4 68Y. TflPER

i ' 36 TIP@78 S 2e Deg S14EPT 14/ 6eP. TRPER & 2e Deg flNHEDRflL

P i

1%

!=;_; Figure of" Mertt, v$ Ct,/S|gm&

1 t,I

i :" r .

- ...... I.......i

i t

: ! 1

i!] '"........... .....-......".............. F...... i

:_*_,a!'" L. 75 ...................................... _-_ ....... _ .......................

1

' i

":i , "" I d

I_o I : I

_-_ LI_ _ .... i............................ :.................. _......................................

.s ........................ ................. 1......... i........................ _....................... *.............. I

; Z].'_'_I_IIIII i i t

-" .05 • eS . O_ . e8 • OS . • '11

!

, {

" at/Sigma

i Figure25. .i

","t 61

J,
!

Thi_ gata Recorded_Processed,and Pe|n_ed UtI1izlng

HPg_4_B/SERIES 460e MRGHETIC TAPE DATA PROCESSING SYSTEM

PLOT SERIES : S-76 TIP COMPARISON; OGE; Mr= e.65

Ftle_.__ Ftle-N_me Plot...._ Plot-Title

3 TIPSI9 1 28 9eg SWEPT W/ 68_ TAPER

13 TIPe38 2 2e geg SWEPT

22 TZPeS5 3 RECTflHGULRR

35 TIPS?4 4 68_ TAPER

3? TZPe?9 5 28 _eg SWEPT W/ 60_ TAPER & 28 geg ANHE_RRL

Ftgure o? Merit vs Ct/Stgma

.S5

• e ....... :::::::::::::::::::::: -. ............. c_::::::::::::.

4

L

•75 ..............................

(_ ,,,..

r. t

t

!

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62

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1 Thtl Oata Re¢or_ed,PPocessed,&nd PPtnted U_tltztng

HP9845B/SERIES 4_ee HRGNETIC TRPE OATA PROCESSZHG SYSTEH

i_ b_,

PLOT SERIES : S-?6 TIP COHPRRISON; IGE; Ht I 8.5| Z/R I 1.2

FI le.__._#Ft 1e-Hame Pl ot_._._ Plot-Tt t le

4 TIP828 1 28 ])eg SWEPT N/ 68P, TRPER

_ .: , 12 T_P837 2 28 l)eg SXEPT

::4 25 T,vP85$ 3 RECTRHGULRR

/_ 32 TXPe?l 4 68P. TRPER ,

39 TXP881 5 28 Deg SXEPT W/ 68P. TAPER & 2S neg _tNHEI)RRL

'r

"r Figure of" HePtt vs Or/SigmA

<_ ...................... , ....................T..............................

.............. ...... I...... _ ............. : .......

i_.... ; S-) ...................... ._---t ........................................................

.;_ _ '1'I

r=,"

.ss _- _ ........... -_ ..........................................................................

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5_ '

, ._ ._S .0_ .@8 .@_ .1 . 1

Ct/Sigm_

Ftgure 27.

i 63
r1

<i

-, OFeltINAL PAGE 15

_ OE POOR QUALII_,

!

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• HP?845B/_ERZES 4_00 MFI_t-tETIC TAPE DI:ITA PPOCE_';ING _YSTEM

PLOT SERIES : $-?g TIP COMPRRI._ON; Zo._E;f4t- O.g; Z,"P- O.75 '

File# F| le-Nimt Plot,# P 1o*,..-T t t. I I.

- 5 TIP023 1 2e D@9 SltEPT W/ 6e_. TFIPER

_; 11 TIP036 2 20 I)eg SWEPT

. 24 TIPeS? 3 RECTFIHGULt:IR

31 TIPO?O 4 68_. TFIPER

_; ,r 4e TZPe82 5 20 l)eg SWEPT W/ 6e_. TFIPER & 28 Dig FIHHEDRFIL

':

i '_7" Figure o_" Merit us C_/Stgma

, _;_ ,85 "................................. :........................... ,........................................... •........

_, -- ......,.........I--..-,................................... :........................ _........ ,......

i

,. J 1

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ii. Ct/Sigma

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,

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._

i,l
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' • 60 %TAPERED

1.08 I 20° SWEPT

SWEPTTAPERED

1.06 I _\

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i Figure 29. S-76 Rotor, GroundEffectAugmentation

I

65

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.... _ _,_ ....
This D&ta Recorded,Processed,and Pr4nted U_tltztng

HPee45B/SERIES 4_ee NRGHETIC TRPE DRTR PROCESSING SY_TEH

PLOT SERIES : TR[L ROTOR EFFECT; S-?e BLRCKHR_K PLUS 28 Deg/3S Deg DOUBLE

SWEPT TIPS; OGE; H_- 0,55

a

F_lelt F_le-Hame Plott) Plot-T4tle

12 TIP119 ! TRRGTOR TRIL ROTOR

4 17 TZP124 2 PUSHER TRZL ROTOR

36 TIF026 3 ISOLRTED NRIH ROTOR

Figure of NtrIt vl ¢t,/S4gm_

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i

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I

i

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Ftgu_e 30.

66

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I

! ORIGINAL PAGE,Iti,

: OE POOR QUALITY

This _ta Re¢orded,Pro_essedt&nd Printed Ut,illzlng

HP9845_/$ERZES 4686 MAGNETIC TRPE DRTR PROCESSING SYSTEM

PLOT i SERIES : TAIL ROTOR EFFECT| S-78 BLRCKHRI4K PLUS 2_ Deg/35 De9 nOU£LE

SNEPT TZP$; OGE| MtJ 8.6

_ File# FI I e-N,me Plot# Plot-Title

t ' _ TZ'Pe25 _ ZSOLFITED MFIIH ROTOR

'_: 13 TIP128 2 TRACTOR TRZL ROTOR

:, 18 TZP125 3 PUSHER TRZL ROTOR

!

'; Figure o? P1er1_ vs.C¢/Sigm4L

,, .85 .................................................................................... 'r...........

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--" .75 ......... _.............. '-_' ............. 4...........

z. :i

-- q. _l

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Ftgu_e 31.

67
!_ Th4$ Data Recorded,Pr'ocessed,and Pr4nted Utillzlng

: HPgS45B/SERIES 4_ee MAGNETIC TAPE DATA PROCESSING SYSTEH

,,.

PLOT SERIES : TAIL ROTOR EFFECT| S-?.0 BLRCKHRNK PLUS 20 I]eg/35 Oeg DOUBLE

SNEPT TIPS; OGE; At,, 0.65

Ft 1eli Ft I e-Htme 1ot, P i._._# Plot-Ti _ le

i-,_: 14 TIPI21 1 TRACTOR TAIL ROTOR

19 TIPt26 2 PUSHER TRIL ROTOR

) . 3? TIP02? 3 ISOLATED HRIH ROTOR

:: Ftgure of" Mert$ v$ Cs/Stgm&

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Figure32.

,=

68

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I

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HPg@45)/SERIES 4600 MAGNETIC TRPE DRTR PROCESSING SYSTEM

PLOT SERIES : TRIL ROTOR EFFECT; S-?e 3LRCKHRWK PLUS 2e Deg/35 Deg DOUBLE

SWEPT W/ 20 Deg RHHEDRRL TIPS; OGE; Htm e.55

File# File-N&me Plot_.._._ Plo_-T|_le

26 TIPISe 1 TRRCTOR TRIL ROTOR

32 TIPI59 2 PUSHER TRIL ROTOR

41 TIPS46 3 ISOLATED MRIN ROTOR

1

Figure o¢ Mer|_ vs C_/Stgma

i L. . ?5 ............... ' .............................................................

Urn] " m *,

o ._'................ _ __'_:I _ ..............................

*m

//

.s ............ -.......................................... !....................................................................

.... I........................... h.......... "" .........................................................

515 ,

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Ct/_igm_

l

Figure 33.

69

...+_,.,_ ,. V
_: This Data Recorded,Processedp&nd Pr|nted Ut4|tzing

HP9845B/SERIE_ 4_0e MAGNETIC T_PE DRT_ PROCESSING SYSTEM

PLOT SERIES : TRZL ROTOR EFFECT; S-?8 BLRCKHRMK PLUS 28 DES/35 DeS DOUBLE

$NEPT N/ 28 DeS RHHEDRRL TIPS; OGE; M_- 8.6.

', File# Ftle-Hame Plottt Plo_-T|_le

2? TIP151 1 TRACTOR TflIL ROTOR

:" I 33 TZPISe 2 PUSHER TRZL ROTOR t

: 42 TIP84? 3 ISOLATED MRZH ROTOR ,

+ Ftgure of" Hert_ vs C_/Stgm&

i i

;: i i i

i

: i : i

-<_- 0 .;' ..... _ _ .... +.......................,

.65 ....."_",'_"t .... _.... .......... :.............................................

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ar

: I i

! +

+ +

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i . +

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l

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Ftgure 34.

• 70

t

.. +,7+, -- ::... -.:,-+. ...... .........
" • (::' ._.;...- , •..

',_, ORIGINAL PAC_ _

: OEPOOR(_.IALII"_

I,: PLOT SERIES : TRIL ROTOR EFFECT; .S-?O BLRCKHflNK PLUS 20 ])eg/35 ])eg 90UBLE

SNEPT 14/ 2g 9eg flHHEgRRL TIPS; OGE; lit= g.65

_-, :., F| te# Ft I e-N&ae Plot# PI ot-Ti t, I •

28 TIPI52 I TRRCTOR TRIL ROTOR

_i_ 34 TIPI61 2 PUSHER TRIL ROTOR

•- 40 TIPe45 3 ISOLRTEZ) IqRZN ROTOR

Figure of Her|t us Ct/Sigmt

" ] , i !

- I !

t : i

. t

] 3

•_:;i o "_ ......... !.............. ] 7_-- _ "-J................................ -p.

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_-_ ...... ,............................................ !............................................... i.........

!

L

,55 ................................................. ..............................

,e= ,as ,e_ ,as ,as , t , _t

,,. Ct/Sigme

....:. Figure 35.

71

.............. _ .............. ,: ....... _ _, ....... ,s...... , ...... _. _- ................. '.
!

This Data Re¢orded,Proce/sedt&nd Printed U_i1_zlng

HPgS4SB/SERIES 46ee MRGNETIC TRPE DRTR PROCESSING SYSTEM

PLOT SERIES : TRIL ROTOR EFFECT| S-78 BLRCKHflWK PLUS 2e Oeg/35 Deg nOUBLE

SWEPT TZPS; ZGE; Z/R= 1,2.; H_= g,6g

J

Ftle__.__._F41e-H&me Plo_# Plot-Title

2 TZPe29 _ ISOLRTED MRIH ROTOR

15 TIP122 2 TRRCTOR TfllL ROTOR

2e TIP12? 3 PUSHER TRIL ROTOR

Figure or" Hertt vs C_/Stgm&

b ! +!

I :

----' : I

_ I[ :

-- °

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g

L //./ : !

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,55 .... _"........................................................................... ".............

•;)S •;)S . ;)_ • ;)8 •e;) .1 • 11

Ct/Sigm

Figure 36.

72
(. This Data Re¢orded,Pr'ocessed,and Prtnt, ed Ut,_l|ztng

_: HPe84SB/SERIE$ 4Gee MAGNETIC TAPE DATA PROCESSING SYSTEM

PLOT SERIES : TAIL ROTOR EFFECT; 8-78 BLACKHANK PLUS 28 Deg/3S Dog DOUBLE

SNEPT TIPS; IGE; Z/R= 8,75 Mr= e.68

__.. , F | 1e# F 41e-Name P1ot,# P1ot,-T | t 1•

16 TIP123 1 TRACTOR TAIL ROTOR

'--I 21 TIPt28 2 PUSHER TAIL ROTOR

."i 38 TIPO28 3 ISOLATE]) PLAIN ROTOR t

; I i;

_i': F|gure o¢ Merit v$ Ct/Stgma

.- • 85 .........

• '<_; I

I

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,/: ]

: 1

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L.

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i i

Ftgure 37.

' !

• %|

•_ 73

I.

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v

,i,_ ORIGINALPAGEIS

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?.

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.i:: SHEPT M/ 20 ])eg flHHEDRRL TIPS; [GE; Z/R. 1.21 Ht,- 0.G0

!,_ F1lelt F11e-Htme Plo*_# Pl ot,-Tl t I e

_.: 3 TZPG43 1 ISOI'flTEZ) MRIH ROTOR

!'° 29 TIP155 2 TRACTOR TflIL ROTOR r

_ 31 TIP158 3 PUSHER TAlL ROTOR ,:

!.

L

• _i:

' Flgure o¢ Her|t, v$ C_/S|gma

_ ._

_.' ,85 ...............................................................................

4

) '

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o1/.. ,.

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,,o

• 74
:--1" '' ORIGINALPAGEI1_ i:

OF.POORQUALITY

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!':: HPge45B,"SERIES 46_'_) r,IRGNETIC TRF'_ DRTR PROCESSING SYSTEM

PLOT SERIES : TRIL ROTOR EFFECT; S-TO _LRCKHRHK PLUS 28 9eg/3S Deg DOUBLE

SNEPT N/ 2e Deg RNHEgRRL TIPS; IGE; Z/R- 0.75 Mr- e.6e

, Ftle.__.__ Ftlt-NaBe Plot.__._g PIo_-Ti_le

', 3g TIP1S? 1 PUSHER TAIL ROTOR

i)' _ " 35 TIP154 2 TRRCTOR TRIL ROTOR

! _ 39 TIP842 3 ISOLRTED MRIN-ROTOR

" Figure of Hertt us Ct/Stgma

iT

i .85 ................ ,...................... ............... r ..............................

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Figure 39.

:i 75
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: Figure 40.

76

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This D_t_ Re¢ordedmProcessed,_nd Prin_td Utilizing

HPgS4SB/SERZES 4£@_ HRGNETIC TRPE DATA PROCESSZNG S'tSTEII

PLOT SE_[ES : TAZL ROTOR EFFECT; S-76 PLUS GS_ TRPER TIPS; O_E; Mr- eo60

Ftle.__ Ftle-H_me Plot_...._O Plot-Tt¢le

, ? TZPe?3 1 XSOLRTE9 HRZH ROTOR

18 TZP[32 2 PUSHER TRZL ROTOR

20 TZP139 3 TRRCTORTRXL ROTOR

Ftoure o? Her4t, vs Ct,/Stgma

•05 ..... _............................................................................. :::: !::.............

0

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Figure 41.

77

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, HPgS45B/SERIES 460e MAGNETIC TAPE 13RTH PROCESSING SYSTEM

Ct/Sigmm

Ftgure 42.

78

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1" HP?845B/SERIES 4_k_0 HAGHETIC TAPE DATA PROCE$:SIHG Sh'_TEH

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:: l, i F 1 I I _ Ft le-Name Plot# Pt ot-T'l t, l,n, l_ TIP@8@ _ ISOLATED PlAiN ROTOR

,. • 12 IIP689 2 PUSHER TAlL ROTOR

' t 14 TIPII2 3 TRflCTOR TRIL ROTOR

_i+ " Ftgure o? Plert_ vs C_/$tg,n&

+;.; + 'I

: i

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1

.i ....................... I......................................... ' ...........I........................ 

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:' 79
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PLOT SERIES 8 TAIL ROTOR EFFECT; $-76 PLUS _0 _4g SNEPT W/ 6e_ TAPER _ 2e De,_

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13 TIPege 2 PUSHER TAIL ROTOR

15 TIP113 3 TRACTOR TAIL ROTOR

Figure o_ Ner4t vs Ct/fl4gm&

Ct/Sigma

Figure 44.

8O

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PLOT SERIES : TRIL ROTOR EFFECT; S-?G PLUS 20 9eg SWEPT W/ 68_ TAPER AN9

26 meg AHHEgRAL TIPS; OGE; Mime,G5

, File# Flle-H_me Plot.__..m##Plot-Title

1 TIP891 I PUSHER TAIL ROTOR

16 TIPe?9 2 ISOLATED MRIH ROTOR

16 TZP114 3 TRACTOR TAIL ROTOR

Figure o¢ Merit vs Ct/Stgm&

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n

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Figure45.

81

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k HPgS45B/SERIES 4(_00 MRGNETIC T¢_PEDRTR PROCESSING SYSTEM

k,

I

PLOT SERIES : TRIL ROTOR EFFECT; S-?(_ PLUS 20 Deg SI4EPT N/ 6eP. TRPER TIPS;

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"• Ft_lure o? Mertt v$ Cf;/Stgma

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2 TIP01? 1 ISOLRTEI) MRIH ROTOR .+

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Ftlett File-Hsme )lotlt Plot-Title

4 TXPet9 1 XSOLRTEO HflIH ROTOR

24 TIPI?8 2 PUSHER TflIL ROTOR

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io 5 TIP@?X 1 I$OLRTED MRIN ROTOR

• 22 TIPX35 2 PUSHER TRXL ROTOR

24 TIP142 3 TRRCTOR TRIL ROTOR

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Figure54. Impactof TailRotoron PerformanceImprovements

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"_ 90

............................................... _____ ...._ - _ __._.C_ _ . . .%<'
p_F =, -

I. Ae_-Na. 2. G_t _lon fro. 3. eK,_mt', C,usollNo.

cR,. 171336

_-4.T,t**,_1 suml_0e 6. ll,s_n o,t,

Experimental Study of Matn Rotor Tip Geometry and Fehruarv 1985

Tail Rotor Interactions in Hover. Vol I - Text 0, I_rformlnlOrglnlnal_Caae

and Figures

7, A,t_(,_ I, I_ml_ Ofl_*_n II_, Not

D. T. Balch and J. Lombardt

t

10.W_k UnitNo,

9. I_lrforminO,fglnSMlionN|meandAd_nl T- 3525

United Tecnnologies Corporation 11, Contractor _nt NO.

Sikorsky Aircraft Division HAS2-11266

Stratford, CT 06601

S3.T_yS.of m nmort a_toa Co_W '

' Gongractor Keport

12 SmmormgAII_©VN,m, ,nclAcldr*, . Aug. 1982-Nov. 198 NASA - Ames Research Center

Moffett Field, CA 94035 14. _Ino _ code

505-42-11

.': 15. $up_ement,ryNotes

,. Point of Contact: Technical Monitor, Charles A. Smith

NASA Ames Research Center, bioffett Field, CA 94035

(415) 694-6714 FTS 464-6714

16 A_trect

With the acknowledgment of the existence of mutual interference between a

hovering main rotor and a tail rotor, a model scale hover te_t was conducted

in the Sikorsky Aircraft Model Rotor hover Facility to identify and quantify

the impact of the tail rotor on the demonstrated advantages of advanced

geometry tip configurations.

The test was conducted using the Basic Model Test Rig and two scaled main

rotor systems, one representing a 1/5.727 scale UH-60A BLACK HAWKand the

others a I/4.71 scale S-76. Eight alternate rotor tip configurations were

tested, 3 on the BLACK HAWK rotor and 6 on the S-76 rotor. Four of these i

tips were then selected for testing in close proximity to an operating tail

1

rotor (operating in both tractor and pusher modes) to determine if the

performance advantages that could be obtained from the use of advanced

geometry tips in a ma_n rotor only environment would still exist in the more

complex flow field involving a tall rotor.

The test showed that overall the tall rotor effects on the advanced tlp

configurations tested are not substantlally different from the effects on

conventional tips and the benefits obtained from advanced tips should be

retained even when operating in the presence of a tall rotor.

• 11.KeyWords(Suited byAuthor(t)) 18. DistributionStatement

Helicopter Aerodynamics Hover

Main Rotor Performance Unlimited

Tail Rotor Interference

Hodel Rotor Test Tip Geometry Subject category - O1

19 Sl_urltyOlmlf,'(ofthlireWt) _0. Iklwr,ltyO01Ndf.(of thl|Nit) _1, No.of Pll_l 2_,PelGe*

UNCLASSIFIED UNCLASSIFIED 90

m ii

*FortalebytheNitlonelTuhnirdIln! formotlonIkirvlfd), Ik)rln0field,Vlrlllnll221111