NASA Contractor Report 175088

Documentation of Ice Shapes Accreted

on the Main Rotor of a UH-1H

Helicopter in Level Flight

{ (NASA-CE-175088) DOCUMENTATION OF ICE N86-22559

!SHAPES ACCRETED ON THE MAIN £C10E OF A UH-1H

; HELICOPTEfi IN LEVEL FLIGHT Final Beport

I {Fluidyne Engineering Corp.) 14 p Unclas

VHC A02/MF AOI CSCL QIC G3/03 05921 _

M.K. Hanson

FluiDyne Engineering Corporation

Columbus, Ohio

and

John D. Lee

The Ohio State University

Aeronautical and Astronautical Research Laboratory

Columbus, Ohio

March 1986

Prepared for

Lewis Research Center

Under Grant NAG 3-374

NASA

National Aeronautics and

Space Administration
TABLE OF CONTENTS

SUMMARY

 1

INTRODUCTION 2

TEST FACILITIES AND PROCEDURES 2

RESULTS AND DISCUSSION 3

REFERENCES e
SUMMARY

Icing tests were conducted on a UH-1H helicopter in

level flight behind a spray tanker near Duluth, Minnesota,

during the winter of 1983-84 as part of the joint NASA / Army

HIFT program. On landing, the ice formations on the main rotor

were documented by casting a set of ten-inch molds on the blade

using a Dow-Corning silicone rubber compound which was initially

liquid at sub-freezing temperatures. Such documentation was

accomplished for eight flights in which the temperature ranged

from -11°C to -22°C and the in-cloud flight times ranged

from 5 to 9 minutes.
INTRODUCTION

The joint NASA/Army Helicopte r Icin g Flight Test

(HI.FT) Program has been outlined in reference 1 while the hover

documentation phase ,and the subsequent dry wind tunnel test

program have been described in some detail in references 2 and

3. The techniques, previously developed were applied to phase 2,

in attempting to document the ice formations accreted on a UH-1H • ' , j ' !

 - >

helic.opter in level flight behind the Army CH-.47C spray tanker.

This, phase of the,program was conducted near Duluth, Minnesota,

during, the months of February and March, 1984, and the details

are presented in reference 4. The documentation of the ice

formations on the main rotor was performed by personnel from

FluiDyne Engineering Corporation, Minneapolis, and that aspect

has been reported in reference 5.

This report summarizes the ice documentation; a dry

wind tunnel test program to determine the section characteristics by using castings from the molds will follow, as for the

hover phase.

TEST FACILITIES AND PROCEDURES

The focal point of the operation was the Air Force

Base at the Duluth Airport, Minnesota, with the aircraft and

operational personnel from the U.S. Army Aviation Engineering

Flight Activity (USAAEFA), and the documentation equipment and

personnel from the FluiDyne Engineerin g Corporation ,

Minneapolis. The test aircraft was a UH-1H helicopter equipped

with instrumentation to record the performance; the spray was

supplied by a CH-47C helicopter equipped with a water tank and a

retractable spray bar; a U-21 aircraft was used to measure the

humidity, the liquid water content and the droplet size in the

cloud; a UH-1H helicopter flew chase to provide photographic
coverage and emergency support. The equipment for molding the

ice formations was that assembled for the hover test phase a

year earlier. FluiDyne also supplied a scissor-lift van

(Figure 1) with a work 'area of 7 feet by 10 feet and the other

miscellaneous support equipment.

The molding compound, as for the hover experiments,

was Dow-Corning silicone rubber compound DC3110, diluted with

Dow-Corning DC200 silicone oil and Catalyst number 4. This was

poured into the mold-boxes (reference 2) which were fixed to the

rotor blade after the aircraft had landed and the rotor was

stopped (Figure 2).

A project engineer on the hover program, Mr. Rory

Harding of Hovey and Associates, Ottawa, assisted in the initial

test run to familiarize the FluiDyne personnel with the molding

technique.

RESULTS AND DISCUSSION

As with the hover phase of the HIFT program, the level

flight case was regarded as a feasibility study and the degree

of success achieved can be attributed to the careful perseverence of all those involved. A variety of problems were

overcome and these are described in references 4 and 5; at the

beginning of the flight tests, the possibility of molding any

significant amount of rotor ice after the helicopter had landed

was uncertain and so the first flights were regarded as tentative as far as documentation was concerned. However, some to

most of the ice formations were successfully molded for eight

flights and the pertinent information has been assembled in the

Table I. The various details of each flight have been recorded

in reference 5.
Figures 3 and 4 show the. results from two such flights

(G and H) fo.r which the reference data are included in the Table

I. The, spanwise distributions of i.ce thickness have been

.plotted in Figure 5. , . ,

The differences in shapes from those of the hover case

are obviously considerable by comparison with reference 3; these

differences may be due to the fact that, although the hover is

an almost steady-state condition, forward flight presents an

. unsteady flow,field to any section, both in speed and attack

angle. Figure 6 shows typical excursions f,or the same four

sections that were treated in hover, with a full excursion

occurring every revolution. These variations, particularly in

;attack angle,, may prevent the kind of formations observed in

hover. On the other hand, the combinations of time and weather

conditions may have produced some erosion of both detail and

shape. In an attempt to answer the last question, the in-flight

performance measurements were bypassed for flight H and the

aircraft brought to the documentation site as quickly as

possible. It was noted that the ice formation and condition

were quite similar to those of the other flights; however, the

. differences are not small and may be attributed only in part to

,the flight conditions.

A wind tunnel test program is planned for at least one

flight from the level-flight phase in a manner similar to that

conducted for the hover phase. A study of Figure 5 suggests

that such a program must should require a much larger data base

than that generated for a hover flight and that some attempt

should be made to,acquire unsteady data, particularly if the

steady-state tests indicate a stall onset at the higher attack

angles.

However, the regularity of the shapes as illustrated

in Figures 3 and 4 suggests that airfoil analysis codes might be
used to aid in determining the aerodynamic characteristics. The

combination of code application together with a selected set of

points in wind tunnel tests for comparison to "tune" the code

for this situation, especially for drag, is proposed as the most

effective (and most economical) technique for obtaining a useable data base.

REFERENCES

1. Shaw,

2.

3.

4.

Robert J. and Richter, G. Paul: The UH-1H Helicopter

Flight Test Program: An Overview. AIAA Paper No.

ojiciw, KuueLt u. dna Kicntet, u. v

Icing Flight Test Program: An 0

850338, presente d at the AIAA

Meeting, Reno, Nevada, Jan. 14-17,

23rd Aerospace

1985.

Sciences

Lee, John D. ; Harding , Rorry ; an d Palko , Richar d L. :

Documentation of Ice Shapes on the Main Rotor of a UH-1H

Helicopter in Hover. NASA CR-168332, Jan. 1984.

Abbott , W . Y. ; Williams , R .

Stella r F. W.: Evaluatio n of

Degradation Caused by Rotor Icing.

Aug. 1983. (AD-A141252)

Abbott , W. Y.; Lockwood , R. A.

Todd, L. L.: Evaluation of UH-1H

Degradation Caused By Rotor Icing.

23, July 1984.

A . ; Belte , D. ; an d

UH-1H Hover Performanc e

USAAEFA Report 82-12,

; Linehan , J. L.; and

Level Flight Performance

USAAEFA Report No. 83-

5. Hanson, M.K. : Documentation of Ice Accretion Shapes from

Helicopter Icing Flight Tests at Duluth, Minnesota During

February and March, 1984. FluiDyne Engineering Corporation

Report.
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ORIGINAL PAGE IS

POOR QUALITY

w ---- :

FIGURE 1. LIFT PLATFORM DURING CASTING

FIGURE 2. ROTOR BLADE AND MOLDING BOXES
FIGURE 3. PROJECTIONS OF MOLDS OF ICE ACCRETIONS IN LEVEL

FLIGHT ( FLIGHT G )
|s

OF

 POOR QUALITY

;r/R = o.8l

FIGURE 4. PROJECTIONS OF MOLDS OF ICE ACCRETIONS IN LEVEL

FLIGHT ( FLIGHT H )
0,6

CO

~ 0,1

UJ

S 0-2

X

0

FLIGHT

/ / FLIGHT G

1 1 1 1 1 1

0.2 0,4 0,6

SPANWISE STATION r/R

0,8 1,0

FIGURE 5. DEPTH OF ICE ACCRETED IN LEVEL FLIGHT

( FLIGHTS G AND H )

10
8 iv\ r/R = 0,77

r/R =

0,93

0012

BOUNDARY

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

FIGURE 6. TYPICAL RANGES OF CONDITIONS EXPERIENCED BY FOUR

SELECTED BLADE STATIONS FOR THE LEVEL FLIGHT CASES.

11
1 Report No

NASA CR-175088

2 Government Accession No 3 Recipient's Catalog No

4 Title and Subtitle

Documentation of Ice Shapes Accreted on the Main

Rotor of a UH-1H Helicopter in Level Flight

5 Report Date

March 1986

6 Performing Organization Code

7 Authorfs)

M.K. Hanson and John D. Lee

8 Performing Organization Report No

None

10 Work Unit No

9 Performing Organization Name and Address

The Ohio State University

Aeronautical and Astronautical Research Laboratory

Columbus, Ohio

11 Contract or Grant No

NAG 3- 374

12 Sponsoring Agency Name and Address

National Aeronautics and Space Administration

Washington, D.C. 20546

13 Type of Report and Period Covered

Contractor Report

14 Sponsoring Agency Code

505-68-11

15 Supplementary Notes

Final report. Project Manager, Robert J. Shaw, Propulsion Systems Division, NASA

Lewis Research Center, Cleveland, Ohio 44135. M.K. Hanson, FluiDyne Engineering

Corporation, Columbus, Ohio? John D. Lee, The Ohio State University, Columbus,

Ohio.

16 Abstract

Icing tests were conducted on a UH-1H helicopter in level flight behind a spray

tanker near Duluth, Minnesota, during the winter of 1983-84 as part of the joint

NASA/Army HIF1 program. On landing, the ice formations on the main rotor were

documented by casting a set of ten-inch molds on the blade using a Dow-Corning

silicone rubber compound which was initially liquid at sub-freezing temperatures.

Such documentation was accomplished for eight flights in which the temperature

ranged from -11 °C to -22 °C and the 1n-cloud flight times ranged from 5-to

9 minutes.

17. Key Words (Suggested by Author(s))

Helicopter icing

Ice shapes

Forward flight

19. Security Classif (of this report)

Unclassified

18. Distribution Statement

Unclassified

STAR Category

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