WD57BSLab.DOC

ABSTRACT

The Flight Control electro-hydraulic research and development capabilities are described. The organization and key personnel are provided followed by a written and photographic tour of the facilities. Examples of previously performed work and techniques used are briefly outlined. This report is presented as an indication and not the limit of capabilities. The facilities and scope of work are constantly expanding, thereby advancing the state of the art.

CONTENTS

Abstract	1
Introduction	2
Key Personnel	3-5
Component Engineering Unit	5
Equipment Research Unit	5-6
Room Temperature Facilities	6
Hydraulic & Electronic Assembly	6
Hydraulic Test Stands	6
Filter Evaluation	6
Gage Calibration	7
Burst Pressure Chamber	7
Extreme Temperature Facilities	7
Safety Requirements	8-9
Control Measuring & Recording	10-11
Oven Test Chambers	11-14
Hydraulic Power Supply	14
Filtration	14
Vacuum Test Chamber	15
Cold Test Chamber	16
Heat Exchangers	17
Support Facilities	18
Environental Laboratories	19
Research & Development Shop	20
System Development & Evaluation Programs	20
Component Development & Evaluation Programs	21
Actuators	21
Servo Valves	21
Pumps	22-23
Fluids	23
Elastomer Seals	24
Metallic Seals	25
Filters	25
Transducers	26
Products	27-28

ILLUSTRATIONS AND PHOTOGRAPHS

Fig	Title	Page
1	Organization Chart	3
2	Room Temperature Hydraulic Test Stand	6
3	Extreme Temperature Test Facility	7
4	Floor Plan of Extreme Temperature Test Facility	8
5	Three Ton C02 Supply System	9
6	Observation Mirror View of #4 Oven	9
7	Oven #1 Control Room	10
8	Oven #1 System	11
9	Oven #2 System	12
10	Oven #3 System	12
11	Oven #4 System	13
12	Test Chamber Thermal Change Rate Chart	14
13	Vacuum Chamber System	15
14	Cold Chamber Interior	16
15	Oil to Oil and Electric to Oil Heat Exchanger	17
16	Environmental Laboratory Shaker	18
17	System Simulator in Large “Walk-In" Oven	19
18	Thrust - Gust - Friction Load Simulator	20
19	Actuator Prepared to Operate Under Load at Temperature	21
20	Servo Valve Test Compartment in Vacuum Chamber	22
21	Pump Mounted to Varidrive in #3 Oven	23
22	Filter Evaluation Test Stand	24
23	Filter Evaluation Particle Count	25
24	Autonetics Hydraulic Components	26

INTRODUCTION

POWER ELEMENTS GROUP OF AUTONETICS FLIGHT CONTROL DEPARTMNT

The Power Elements Group of Autonetics originated from the Power Elements Section of the Electro-Mechanical Department of the North American Aviation Aerophysics Laboratories.

The function of the Power Elements Group is to procure or develop the power portions of flight control equipment. Primarily, this covers the power servo mechanisms which operate the aircraft control surfaces or other controlling devices. Though not specifically stated in the Group name, the state of the power servomechanism art presently dictates that most of the work be done in the field of hydraulics.

In order that the hydraulic power supply system have dynamic characteristics which are compatible with the power servos, the Power Elements Group, in many cases, designs the complete hydraulic system. The requirements of such design for very high speed aircraft has lead the Group into research In the field of high temperature hydraulics. The NAVAHO missile program in particular has provided emphasis on high temperature,

The Power Elements Group has a responsibility for work in its field which stretches from the conception of an idea to troubleshooting on installed aircraft. The Group works with Preliminary Design and Preliminary Analysis Groups to establish basic design parameters. From these the Power Elements Group develops equipment to suit the task requirements and produces manufacturing drawings and specifications of the components, The Group then serves as a technical consultant to Project Engineering offices, Manufacturing Departments and Field Test Activities.

In order to handle these manifold responsibilities,, the Group is sub-divided along task lines into two Units. In each of these Units can be found design engineers, research engineers, test engineers, draftsman and technicians. Thus, within each organizational entity can be found the skills required to perform any phase of its task.

Fig 1 Organizational Chart

KEY PERSONNEL

The Power Elements Group of Autonetics consists of technical personnel including specialists, engineers, analysts, test engineers, designers, draftsman, and technicians, forming a well-rounded organization experienced in all phases of high-temperature hydraulic work. Among those whose efforts would be brought to bear on a program would be the following list of key personnel

George R. Keller

Mr. Keller is the Power Elements Group Leader in the Flight Control Engineering Department. As such,, he would be in charge of work to be performed under any proposed efforts. Mr. Keller graduated from Brown University in 1940 with an Sc.B. in Mechanical Engineering. This has been supplemented by graduate studies at UCLA.

Since receiving his baccalaureate degree., Mr. Keller has acquired a broad engineering background, including work with Vought-Sikorskv Aircraft, Solar Aircraft, and Convair. He has been with North American Aviation, Inc.,, since February 1950.

Mr. Keller is a member of SAE Committee A-6. Aircraft Hydraulic and Pneumatic Equipment; SAE Committee A6-0. Aircraft Hydraulic Pumps, Motors and Air Compressors; SAE Committee A-6A, Chairman,, Hydraulic System Materials. He is a Civilian Consultant to the Assistant Secretary of Defense (R & D) on the Working Group on Hydraulic Fluids and Lubricating Oils. Mr. Keller has presented a number of papers on high temperature hydraulic systems and the design of aircraft hydraulic servomechanisme and has had his book, "Aircraft Hydraulic Design", published by the Industrial Publishing Corporation, Cleveland, Ohio. Several of the papers presented are:

1. Keller, G. R., “Hydraulic Fluids for High Temperature Operation”, Proceedings of Symposium on Synthetic Lubricants and Their Applications, Research and Development Board, Department of Defense, Washington, D. C.0 May 1953 (Confidential).

2. Keller, G. R., "Adventures in Extreme Temperature Hydraulics", Reprint #71., SAE National Aeronautic Meeting, New York, New York, April 20-24, 1953.

3. Keller, G. R., "High Temperature Aircraft Hydraulics", Paper No. 56-AV-5, ASIE Aviation Conference, Los Angeles, California, March 14-16, 1956.

4. Keller, G. R., and Buxton, E. R... "The Synthesis of Aircraft Hydraulic Servos", Reprint No. 839, SAE Fational Aeronautic Meeting, Los Angeles, California, October 2-6. 10,56.

Louis W. Strobel

Mr. Strobel is the Power Elements Group Staff Engineer. In this capacity he is responsible for coordination of the technical efforts of the two units mentioned below. He was graduated from the University of California at Berkeley with a B.S.M.E in 1951. He is a member of Tau Beta Pi and Pi Tau Sigma. He has supplemented his degree with several advanced servomechanism courses at UCLA.

Mr. Strobel has been with Autonetics five years. During this time he has worked on missile control system hydraulic components,, including servovalves, and control systems specifications.

G. W. Sargent

Mr. Sargent is the Supervisor of the Component Engineering Unit, In this capacity, he would be responsible for any Autonetics design and development of the components required by a proposed effort,, He was graduated from the University of Michigan with a BSIC, and has taken additional courses in Electronics Theory at UCLA.

Mr. Sargent has been with the Company since 1951, first as a research engineer and then as Supervisor. He has had considerable experience in the design and development of missile and airplane hydraulic systems, components, and high temperature servomechanisms.

P. H. Stafford

Mr. Stafford is the Supervisor of the Equipment Research Unit of the Power Elements Group. Mr. Stafford is in charge of engineers designing and evaluating systems, evaluating components, and conducting extreme temperature and fluid contamination research programs,

He was graduated as a Mechanical Engineer from Cornell University in 1936. He has taken supplementary studies at California Institute of Technology.

Mr. Stafford has had aircraft and missile hydraulic experienced with Kaiser Fleetwings and the United States Navy. Prior to joining North American Aviation in March, 1952, he was the Chief Engineer of the Kenyon Instrument Company. He is a member of Technical Committee N. Hydraulic Fluids, of the ASTM and the Chairman of Section I. Aircraft Applications, of Technical Committee N.

J. R. Anderson

Mr. Anderson is a Senior Design Engineer with the Power Elements Group. He would be assigned responsible design work under a proposed effort. He was graduated from the University of Minnesota as a Bachelor of Aeronautical Engineering.

Mr. Anderson has been with this Company since 1951. Prior to that time he had extensive engineering experience with Northwest Airlines. His experience in the design and development of hydraulic equipment for flight is very broad. Before joining Autonetics, he was active In the design of flight control equipment for the F-86t F-100, and AJ-3 airplanes while attached to the Los Angeles Division of the Company. His work at Autonetics has been in the capacity of lead designer on both missile and aircraft projects.

Darrell W. Landau

Mr. Landau is a Senior Research Engineer in charge of the high temperature facility. In this capacity, he would be responsible for the development of adequate test facilities for a proposed effort. Mr. Landau holds a B. S. in Mechanical Engineering from Kansas State College. He has taken supplementary studies at UCLA. He received Air Force Engineering Officer technical training at Yale University.

Before coming to north American Aviation in March, 1955,, he had aircraft experience as supervisor in Process Engineering with General Motors Corporation. Prior to that time he served overseas as an Air Force aircraft maintenance engineering officer. He is an associate member of ASME and senior engineering member of ASTE.

Joseph H. Schramer

Mr. Schramer is a Senior Design Engineer with the Power Elements Group. He would be assigned responsible design work under a proposed effort, He attended Illinois Technical and Austin Junior College in Chicago, Illinois and Citadel in South Carolina.

Mr. Schramer has directed designs on NAVAHO missile components and yaw and pitch damper aircraft components. He has done basic design of airborne hydraulic servos, including the electrical pickoffs and circuitry’s involved. He has been employed at Autonetics since March 1951.

Mr. Schramer's previous employment experience includes 10 years sheetmetal; 6 years, plastics; 6 years, welding techniques; and 7 years, die casting design. Mr. Schramer holds four patents on mechanical devices and fabrication techniques.

COMPONENT ENGINEERING UNIT

This unit is responsible for the engineering design, development, environmental testing, and production liaison of all power control servos, electromechanical, electro-hydraulic, hydraulic and pneumatic components used in airborne actuating systems manufactured by Autonetics.

Design consists of analyzing the system functional dynamic requirements to determine whether new basic concepts are required or previous standard design concepts currently used in Autonetics "shelf items" are best adapted to the components. With this knowledge a drawing layout of the component is made to fit within the required space envelope while retaining a minimum component strength to weight ratio.

Development consists essentially of refining prototype components prior to their release to production manufacturing. This is accomplished by laboratory tests such as vibration, temperature extremes and dynamic performance,

Environmental testing consists of subjecting the component to accelerated life tests to prove reliability of the component. It may be distinguished from development testing in that it is performed on production type units rather than prototype units.

Production liaison consists of preparing and maintaining-drawings.. process specifications, and providing technical assistance for the production manufacturing of components.

EQUIMENT RESEARCH UNIT

The Equipment Research Unit is responsible for analysis and evaluation of airborne system requirements, the preparation of specifications for components, the evaluation of vendor-supplied components the development and maintenance of an extreme temperature facility, and long range research programs.

The system functional requirements are defined by coordinating with the responsible airframe manufacturer, followed by the formulation of a system specification and design.

Specifications covering the performance requirements of all components are also provided,

Qualification tests on vendor-procured items as electro-hydraulic servovalves, pumps, relief valves, etc. are the responsibility of the Unit.

An extreme temperature test facility has been developed and maintained for the purpose of carrying on the research, development, and engineering evaluation of hydraulic components and hydraulic servo systems.

Basic research programs are carried on by this Unit relative to; static and dynamic seals, hydraulic fittings,, fluid contaminants, and hydraulic fluids.

Prototype hardware is usually assembled into a simulator or mock-up to provide operating conditions as closely as possible. System evaluation tests are then run and recommendations made of desirable design changes. The system is constructed such that it may be tied into an analogue computer for flight control characteristics studies.

The Unit provides operational support when desired during and after installation to ensure satisfactory system performance,

Fig 2 Technician Stevens at Room Temperature Hydraulic Flow Bench and Electronic Test Consoles

ROOM TEMPERATURE FACILITIES

The room temperature laboratories are fully equipped with oscilloscopes, recorders, meters, and other lab aids necessary for refined work. Although the Group is engaged primarily with hydraulics it has never divorced itself of the close bonds between electronics and hydraulics.. A program of training all personnel in the use of both electronic and hydraulic equipment has appreciably enhanced the effectiveness of laboratory activity.

Hydraulic and Electronic Assembly

This is an area of approximately 1800 squar6 feet arranged to provide optimum working conditions and handling of parts. Components are assembled for testing and disassembled for study in this area. Electronic amplifiers, oscillators, and related test equipment for programming of tests are also assembled and checked out in this area.

Hydraulic Test Stands

Four Sprague test stands capable of 4000 psi and 10 gpm are used for evaluation and tryout at room temperature prior to testing at extreme temperatures or other environmental conditions.

Filter Evaluation

This is a dirt-free area where filters are evaluated. Included is a 15 gpm pump at 3000 psi for passing contaminated samples through filters. A sample washing stand, a microscope, particle count bench, and related equipment are included.

Gage Calibration

This work is conducted in the dirt-free area. Periodic checks and records are maintained to assure quality instrumentation of test setups.

Burst Pressure Chamber

A burst pressure chamber,33” x 33" x 40” and capable of 30,000 psi is used to evaluate actuator housings and other components such that optimum strength vs. weight ratios are obtained.

Fig 3 Bldg 123 Downey, Extreme Temperature Test Facility

EXTREME TEMPERATURE FACILITIES

In 1951 Autonetics established an extreme temperature hydraulic test facility. This facility was constructed to give maximum support to weapon system contractors in the field of current and long range testing on hydraulic systems and components under exposure to high and low ambient temperatures. The expansion of the test facility and the development of special high temperature test techniques have added many contributions to the state of the art.

The facility consists of four conventional electrically heated circulating blower type ovens, one vacuum chamber oven, one cold chamber, and all the necessary hydraulic power supplies, heat exchangers, support equipment and controls necessary for their full utilization. The facility covers 6000 square feet. It has four test cells added to one side of a World War II bombshelter. The bombshelter has been converted to provide control rooms for each of the test cells. The picture shows the labyrinth entrances to the test cells designed to maximize the use of the facility without compromising the safety of operating personnel.

Current arrangement of equipment permits testing at ambient temperatures ranging from -105OF to 1200'F with continuous flow heat exchange systems providing hydraulic fluid at 8 GPM and 4500F. The vacuum oven provides ambient thermal acceleration to 1000OF in 2 minutes and sea level to 70,000 feet pressure altitude simulation in 90 seconds.

Fig 4 Floor Plan of the Extreme Temperature Test Facility

The versatility of this facility provides a flexible tool with which Autonetics can be of service in helping to solve the specific and difficult problems of extreme temperature systems as directed by the weapon system contractor. Programs are currently underway to boost the operating parameters of the facility to greater capability.

The successful completion of high temperature testing is a far more complex task than tests run at room temperature. Considerable progress has been made in reducing the time and effort required to perform each test.

A guiding factor in the development of the Autonetics high temperature hydraulic test facility has been that it must lend itself to new applications and problems. It is this factor that makes the facility and associated personnel extremely capable in the support of the Military and airframe companies.

Safety Requirements

The facility is set off by itself because of the possibly hazardous nature of high temperature hydraulic testing. The test cell walls are designed for an over-pressure of 1.6 psi and are constructed of concrete blocks containing horizontal and vertical reinforcing rods and filled solid with concrete. The roof consists of 2” x 10” wooden beams covered with corrugated sheet metal lightly attached so it can readily blow off. The underside of the beams is covered with heavy wire mesh, comprising a retaining net.

Each cell entrance is covered with a sliding door hinged in the top so as to blow outwardly to dissipate pressure. The cell doors are surrounded by a labyrinth of blast walls.

In view of the hazardous nature of this work a fireman is on duty at the test facility whenever a high temperature test is in progress and a red warning flag is raised at the facility entrance. A flashing red light and chain barrier provide warning and prevent access to any test cell in operation at temperature. Each room can be instantaneously flooded with 100 pounds Of C02 and each oven interior with 50 pounds of C02 from solenoid-operated fire bottles. Emergency 24 V DC battery operation of fire bottles is provided in case of power failure. Each oven test is operated in a C02 atmosphere. A 3 ton liquid C02 tank is equipped with a refrigeration unit for controlling pressures. An 18 kw heater unit converts the liquid to gas. The gaseous C02 is metered through a manifold to each oven as required to keep the oven oxygen content below 6%. Oven oxygen content is continually indicated on an oxygen analyzer.

Fig 5 CO2 Supply for Creating an Inert Oven Atmosphere

Fig 6 Overhead movable mirrors for seeing the far side of the test cells

Complete observation of test equipment is made difficult due to its hazardous nature. 12” by 24" shatter proof glass windows are provided between the control rooms and oven cells. A system of mirrors motorized to rotate and tilt are used for viewing hidden areas. Opposite is a mirror view of the #4 oven room. Special visual problems are solved through the use of a closed circuit television system.

A complete intercom system enables verbal contact between personnel making test setups in the test cells and control rooms and provides for audio observation of test noises.

Fig 7 Technician Larry Hein at Test Cell #1 Control Panel

BOMBSHELTER CONTROL ROOM

Control Room Equipment

Each high temperature control room is equipped with automatic temperature controllers recorders, electronic power supplies, counters indicators, and equipment for furnishing various types of test inputs and controls. These types of miscellaneous and special equipment are capable of supporting a broad range of testing data acquisition and process controlling. A partial view of the #1 control room is shown.

Porting Controls

Dependable positive shut-off, flow rate regulation, and pressure regulation of high temperature fluids are usually accomplished by the use of needle valves. Where possible, these valves are operated with extension shafts between the control room and oven room. An Autonetics designed motor-operated needle valve, used for difficult to-reach locations, incorporates indicator lights to show fully closed and opened positions.

Flow Measurements

The method of taking flow measurements is dependent upon the pressure, temperature, and rate of the flow in question. High temperature fluid leakage (low flow) is collected in a "Ull tube system with one leg in the oven cell and the other in the control room. Glass type flow meters following heat exchangers are used for measuring all ranges of flow at low pressures. Turbine and positive displacement rotary types, used at high temperatures and pressures, provide frequency outputs for monitoring and recording fluid flow.

Pressure Measurements

Pressures are taken in the conventional manner using standard pressure gages and pressure transducers. The pressure line pickoffs are routed such that the indicating devices operate within reasonable temperature ambients to maintain their reliability and accuracy.

Temperature Measurements

Most temperature measurements are made with thermocouples inserted directly into the fluid passageways. These are monitored on 24 channel temperature indicators located in each control room.

Recording-Instrumentation

Oven temperatures are recorded by controller recorders. Sanborn, Brush, and Offner recorders are used to provide dynamic data for analytical study.

EXTRREME TEMPERATURE FACILITIES

Fig 8 Research Engineer Darrell Landau and Technician Andy Laslofy preparing test setup in #1 Test Cell

The oven located in the #1 test cell has a maximum temperature of 1200 deg F. It is a conventional type of oven with electrical heaters and circulating blower with a power input of 60 kw. The chamber size is 60” wide, 44-1/2" deep and 49" high. Figures 8 through 11 are photographs of each of the ovens. Figure 8 is a view of #1 oven, including an actuator ready for test while operating under load.

The oven located in the #2 test call has a maximum temperature of 800 deg F. It is a conventional type of oven with electrical heaters and circulating blower with a power input of 30 kw. The chamber size is 37” wide, 31-1/2" deep, and 40” high. This oven has been used primarily for evaluation of dynamic and static seals.

Fig 9 Oven #2 in Test Cell #2 – Actuator Load Fixture for Seal Testing to right under door

Fig 10 Technician Beany Miller preparing for pump test in #3 Oven – Varidrive to right behind door

The oven located in the #3 test cell has a maximum temperature of 800 deg F. It is a conventional type of oven with electrical heaters and circulating blower with a power input of 84 kw. The chamber size is 71-1/2 “ wide, 35” deep, and 36” high. This oven is equipped with a 25 HP variable speed drive extending through the oven wall for powering pumps. This oven has been used to evaluate Pumps, fluids and complete systems.

Fig 11 Technician Elmer Subky Preparing for test in #4 Test Cell

The oven located in the #4 test cell has a maximum temperature of 800 degF. It is a conventional type of oven with electrical heaters and circulating blower with a power input of 24 kw. The chamber size is 48” wide, 21” deep, and 40" high.

Refer to the following chart for the thermal rates of each of the test chambers.

Fig 12 Temperature Rate of Change for each Test Chamber

Hydraulic Power, Supply

Conventional hydraulic power supplies of 8 gpm capacity are located in each of the test cells. Two 20 gpm units are installed as a central supply capable of supplying each test cell. These units are generally not operated in excess of 200 deg F fluid temperature. The composite arrangement provides wide versatility in making test setups Including testing with more than one type of fluid at a time. Fluid pressures and flow rates are remotely varied and controlled to meet test requirements. All reservoirs are vented to a nitrogen atmosphere. Multi-stage hydraulic hand pumps are on hand for special applications and proof testing.

Filtration

Extensive filtration and contamination safeguards are taken to maintain adequate fluid properties for each test. Low temperature, two micron rating paper type filters are used in the low temperature portions of the systems. Sintered bronze and steel mesh filters are used in the high temperature portions of the systems. Reservoir supplies are repeatedly circulated through Fullerie-earth filters. Periodic checks are made to determine contamination level by magnification count of particles captured in millipore filter paper. Chemical analysis checks are also periodically made on the fluids used, unless a test is being conducted to determine the effects of contaminant in which case a known quantity of the prescribed contaminant is added to the clean fluid.

Fig 13 Vacuum Chamber setup in #4 Test Cell

Vacuum Chamber

A vacuum chamber is located in the No. 4 test cell. The usable chamber compartment size with the heaters presently installed is 10 inches wide, 14 inches long and 4 inches high. The present heaters have an input of 18 kw, a max. temperature of 1600 degF and are controlled by saturable reactors because of the low heater resistance at room temperature. A 27 ofm vacuum pump is used to evacuate the 16 inch diameter by 24 Inch long chamber to simulated altitude pressure at a rate of 70,000 feet in 90 seconds with a maximum practical limit of 100,000 feet. The view shown is of the closed chamber and some of its controllers.

Conventional type ovens using electrical heaters with circulating blowers and an inert atmosphere require several hours to heat and cool down compared to a few minutes for a vacuum chamber. Refer to the previous chart for the thermal rise rate. The circulation of an atmosphere about a component creates a greater BTU absorbtion by the test item than if the item is subjected to the same temperatures transmitted by radiation only. The vacuum chamber has been used by Autonatics to supplement the conventional ovens and thereby extend the scope of the facility.

CO2 serves a two-fold purpose, first to provide low temperature thermal shock; and secondly, to automatically be fed into the vacuum chamber as an inert atmosphere for preventing fires should the vacuum be lost while at temperature.

Using the vacuum chamber, the facility extends its capability to making known the problems to be faced in outer space travel where differential radiation heat loads magnify their importance. The navigational accuracies required in space flight are extremely critical such that optimm simulation of actual conditions must be utilized.

Fig 14 Cold Chamber Interior

Cold Chamber

The cold chamber is located in a frame building attached to the oven control rooms and is capable of a minimum temperature of -105 deg F. The conventionally insulated chamber is cooled by chilling alcohol with dry ice and blowing the chamber atmosphere over the cooling coils. The chamber is 71" wide, 48” deep and 31” high. The chamber is equipped with a 25 HP, 3600 RPM drive extending through the chamber wall. A view of the cold chamber interior is shown. The chamber is large enough to accomodate the operation of a full system including the pump. The chamber pump drive combination provides an excellent instrument for the evaluation of low temperature characteristics of hydraulic fluids.

Fig 15 Oil to Oil and Electric to Oil Heat exchanger

Heat Exchanger Equipment

Heat exchangers are connected between the hydraulic power supplies and the oven test unit to provide controlled temperature staging and dependable operation of the facility hydraulic power supply equipment. In a conventional setup the oil flows from the pump through an oil to oil heat exchanger to an electric to oil heat exchanger and then to the test item in the:-oven. It returns from the oven to the oil to oil exchanger then through a water to oil heat exchanger back to the p=p reservoir.

The oil to oil exchanger units are designed by Autonetics. Each unit is approximately 2-1/2" diameter by 6’ long and made of high strength stainless steel tubing capable of withstanding 3000 psi at 600 deg F on the pressure side and 1000 psi at 600 deg F on the return. Existing units have a heat exchange surface area of approximately 2.75 sq. ft. and a coefficient of heat transfer of 60 BTU/hr. sqft- deg F at 8 gpm. New units now being constructed will permit operation at 1000 degF with 4000 psi. The total oil to oil exchanger bank for a given test is created by stacking a sufficient number of units and connecting them either in series or parallel to meet heat transfer and pressure drop requirements.

The electric heat exchangers are also an Autonetics design. The fluid flows through stainless steel tubing separated from electric heater elements by milled aluminum plates. This arrangement provides a heat sink for stable temperature regulation and permits control of the temperature in contact with the fluid. This prevents the possibility of adverse cooking and breakdown of oil. The heat input into each unit is approximately 30 kw and is capable of applied temperatures up to 750 deg F. A new design will permit applied temperatures up to 1000 deg F at 4000 psi.

The water to oil heat exchangers are of a tube in a tube design with the oil portion capable of withstanding 4000 psi at 700 deg F.

The composite heat exchange system is such that it is self purging of gases, readily responds to automatic control and lends itself to various temperature staging applications. The oil to oil and electric to oil exchangers are mounted in portable insulated cabinets which reduce the heat losses to less than 2%. The picture shows a typical arrangement. Present arrangement of units will provide delivery of 450 deg F oil at 8 gpm with oil inlet to exchangers at 200 deg F and a maximum oil contact temperature of 500 deg F. Other combinations are readily obtainable.

Fig 16 Hydraulic actuator on Shake Table in Environmental Test Lab

SUPPORT FACILITIES

Environmental Laboratories

The Autonetics Environmental Laboratory completes the facilities necessary for engineering research and for developmental, proof, and acceptance testing in compliance with Military specifications or contracts. Chambers and equipment for testing under conditions of extremes of humidity, simulated altitudes, salt-fog, sand and dust) fungus, oil immersion, vibration, shock, and acceleration are available to supplement the extreme temperature facility. The environmental laboratory includes more than 10,000 square feet of floor space and testing facilities representing an investment of more than $520,000. The many years of experience gained on such programs as the F-86 and F-100 aircraft, and the NAVAHO missile have resulted with a staff of highly qualified engineering personnel, experienced in all phases of environmental testing. These facilities and personnel are readily available to the Power Elements Group.

Fig 17 Walk in Test Oven G26 Navaho Missile Hydraulic System on the Iron Bird

Research-and Development Shop

The Flight Control Department Shop with a floor space of approximately 10,000 square feet is used for the building of research and first part items. This shop is staffed with highly qualified machinists and equipped to handle all but highly specialized processes required in the manufacture of hydraulic components. Previous programs have resulted in personnel capable of skillfully handling unusual types of materials that are used to make research items. A close working arrangement has developed between machinist and engineer thereby reducing delays and speeding results. A simple but effective system of advanced estimates versus actual time spent is maintained for each job, thus enabling efficient programming and reporting on project status.

SYSTEM DEVELOPEMENT AND EVALUATION PROGRAMS

System simulators of varying complexity are utilized to evaluate the integrity of system design prior to actual flight testing. Prototype or production components are used and hydraulic lines, sizes and lengths are equal to the in-ship values. Mechanical loads due to aerodynamics, inertia, friction, thrust misalignment, and hose restraint are simulated as accurately as they can be defined. Ambient temperatures and heat loads are simulated with the use of ovens and radiant plates. It is thus possible to, for example, size an accumulator for the worst in-flight case.

The simulator can also be connected to an electronic analog computer to provide actual system characteristics for flight control stability and accuracy problems. This type of effort very often discloses errors due to ideal mechanization of the hydraulic system in the early flight control system development stages.

Figure 17 shows a simulator in a large "walk-in" oven in which a test at an ambient temperature of 550 deg F was conducted.

The small simulator in Figure 18 shows a method of applying thrust, gust, and friction type loads to a rocket engine gimbaling actuator.

Fig 18 Thrust, Gust, Friction Load Cylinder

COMPONENT DEVELOPMENT AND EVALUATION PROGRAMS

Actuators

In development, actuators pass through the usual evolutionary processes from the drawing board through room temperature tryout, environmental testing, and burst tests. One of the most critical phases is actual operation under load at temperature. In this test procedure a framework houses the test actuator and its load device. The load portion is jacketed and inter-connected for cooling purposes so that commercially available parts can be utilized. All components not themselves being tested are protected so that dependability of test runs are assured. Figure 19 indicates a typical test setup.

The loads are applied to each actuator to simulate in-flight loading. All inputs to the test item as system oil temperature and pressure; cooling oil temperature, pressure and flow rate; heat loads; etc., are carefully regulated. This requires remotely regulated hydraulic circuitry and heat exchange systems. Signal inputs to the actuator servo-valve are programmed to simulate flight command signals for the particular component,

The performance of the system is fully instrumented. Where possible., the operation of the system is automatically regulated so that the operator can concentrate on the performance of the test item. All data are recorded periodically for analytical study and the writing of test reports.

The experience gained in running these tests results in constant refinement of test procedures as well as valuable information on which to base design changes.

Fig 19 Actuator prepared to operate under load at temperature

Seryo-valves

Extensive measures have been taken in order to evaluate and qualify servo-valves thoroughly. This critical component was originally tested in standard type ovens under normal atmospheric pressure. It became increasingly apparent that heat loads at sea level did not properly simulate flight conditions.

To correct these ambiguities, a box was made simulating the compartment area surrounding the servo-valve and on which reliable compartment surface radiating temperatures were available. The box was then covered with radiating heaters to cause each surface of the box to reach its particular temperature. The entire package of heaters, box, and valve was then surrounded by a chamber and the chamber evacuated to proper altitude simulation. The apparatus was designed to provide the same thermal and altitude rise rate seen by a missile. The accompanying picture shows a partial view of the box and one of the heaters. The heaters are so arranged that differential radiant temperatures can be applied. Differential temperatures of 400 deg F have been maintained for periods up to 8 hours.

All electrical and pressure connections are completed to the control room. The actuating cylinder is placed outside the chamber to eliminate excess heat problems and to facilitate calibration of the circuit. Tests have been conducted from room temperature to 1200 deg F with oil temperatures from 100 to 500 deg F and hydraulic pressures of 3000 psi applied to the valve pressure port.

The valve is driven by an amplifier receiving input signals from a low frequency oscillator or from a signal generator programming simulated flight inputs. A balanced area actuator is normally used. The actuator moves a position pick-off for completing a closed loop. The feed-back and command signals are plotted on a dual channel continuous recorder.

Fig 19 Servo valve Test Compartment in Vacuum Chamber

The vacuum chamber permits environmental testing within limits described under Vacuum Chamber. The oil temperatures are automatically regulated by an oil heat exchanger system described under Facilities.

Tests are operated at room temperature prior to temperature runs for tryouts and calibration. These tests are then repeated after the temperature runs for observations of performance changes.

Pumps

Hydraulic pumps have undergone extensive testing at Autonetics The present arrangement of equipment enables the evaluation of pump; operating with fluid and ambient temperatures ranging from -105 to 800 deg F. Actual tests have been performed with cold starts at -65 deg F and high temperature runs with 400 deg F oil and 600 deg F ambient. Included in these temperature ambients have been pump life tests with dynamic simulation of system characteristics. Pump response to typical system pressure impulses and flow rates have been recorded. Pumps have been vibrated at frequencies up to 2000 cps at 25 g input acceleration while delivering system flow rates.

A variety of pump types can be tested individually or with complete systems at speeds up to 8000 rpm.

Fluids

The test program for evaluating potential high temperature hydraulic fluids is done in two phases.

Phase one, the screening of fluids, is done in the Autonetics Materials Research Laboratory. Here the physical properties of various fluids are determined at both normal and elevated temperatures. Fluids exhibiting superior qualities are then subjected to dynamic testing.

Phase two, dynamic testing of a fluid,, is accomplished in a system consisting of a reservoir, pump., filter, servo-valve and actuator. The entire system is isolated in an extreme thermal environment and operated for a specified period of time. Qualities of a fluid are determined during a test run by its effect on the dynamic response of the serve system. The pump, filters and fluid are examined and analyzed upon completion of the test runs to determine adverse characteristics of the fluid.

Fig Pump mounted to Varidrive in Oven #3

Elastomeric Seals

Aircraft and missile hydraulic systems operating in the 400 to 500 deg F temperature range have presented critical problems in static and dynamic sealing. To satisfy the demands of any specific hydraulic system a two-phase program is followed in the selection of elastomeric seals.

Phase one, the screening and evaluation of available polymers, is done in our Materials Research Laboratory. The ability of a polymer to resist thermal and chemical decomposition is established. The change in physical properties of a polymer after immersion in a specific fluid at elevated temperatures is determined. This type of testing aids in choosing elastomeric compounds possessing the greatest potentialities as a high temperature seal material.

In phase two, dynamic tests, seals manufactured from the most desirable compounds are installed in actuator and subjected to cycling tests at both room temperature and elevated temperatures. Two types of tests are used in the determination of dynamic sealing characteristics.

In Type I an actuator is cycled over a given stroke and at a given rate for a predetermined number of cycles against a simulated load. Success or failure of a seal is predicated on the number of cycles completed at temperature, and the rate of leakage flow past the seals.

In Type II,, an actuator is cycled in response to a random noise input signal. In this form of input signal a low frequency sinusoid represents the response of a surface control servo to the phugoid of the airframe. Upon this sinusoid is superimposed a random noise signal which simulates the response of a servo to aerodynamic gusts, In this type of test the number of hours of operation at temperature is used as the criterion. Testing is continued until a sharp increase in leakage rate is observed.

Fig 22 Filter Evaluation Test Stand

Metalic Seals

In certain applications the high temperature environment precludes the use of elastomeric seals. A significant amount of engineering know-how has been attained in the development of dynamic and static metal seals. Piston and shaft seals have been designed and successfully tested in the same manner previously described. Metal boss seals have been developed which have been successfully used under conditions of extreme temperature and pressure. Further study and research is continually being conducted to advance the state of the art of metal seals.

Filters

General methods for testing and evaluation of hydraulic filters have been advanced to the point where Autonetics is now equipped to evaluate any type of hydraulic filter.

Fig 23 Technician John Hockinsmith making test sample readings

To obtain reproducibility in test results, a standard test procedure is followed for the operation of a hydraulic stand designed explicitly for the testing of filters. Another standard procedure is used for the actual analysis of fluid samples taken during the testing of a filter.

The laboratory area used is arranged and air conditioned to provide a dirt-free atmosphere for performing this type of work.

Laboratory equipment includes a small laboratory sink,, work benches,, and the hydraulic test stand. Analytical equipment consists of an American Optical Company stereoscope and a Bausch and Lomb research microscope.

Unique features of the special hydraulic test stand are (1) it can be used to test filters on single dirt passes, or (2) it can be rearranrd to test filters under circulation of dirt in the hydraulic fluid, 3 ) built as a portable unit, the stand can be used to test filters in other locations, The two most common locations are the high temperature facility and the environmental laboratories. Using the hydraulic stand, several filters have been put through complete vibration testing under "full flow" conditions with OS45-1 fluid. This type of testing agrees more closely with operational conditions than did the older procedure of vibrating filters which have only been filled with fluid.

Maintenance of hydraulic fluid cleanliness is accomplished with two filters designed and built by Autonetics. These units use Millipore filter paper as the filter medium and can handle fluid flows of 1 gpm up to 9 gpm. They produce fluid having no particles greater than 2 microns in diameter.,

Present equipment will enable Autonetice to test filters for efficiency to the new proposed MIL-F-8815 specification. In addition, it will make possible the testing of filters with fluids other than hydraulic oil.

Transducers

Autonetics has developed special equipment for evaluating and qualifying linear and rotary motion transducers such as used for position feedback in closed loop hydraulic servo systems.

These transducers can be tested while operating at thermal environments ranging from -65 deg F to 1500 deg F. Thermal chambers and equipment are arranged to move and measure the magnetic probes or rotors with a linear accuracy of .0001" or 1/10 of 1 deg rotation.

The current test devices now handle transducers with lengths up to 22" long with 8-1/2" strokes. Larger transducers could be readily evaluated by using the large ovens described under facilities.

The electrical measurements routinely made on transducers consist of scale factor, sensitivity, linearity, phase shift, power consumption, harmonics and noise, null voltage and insulation resistance.

All the standard environmental tests can also be made on these transducers such as vibration, shock, acceleration, humidity, salt spray, sand and dust, fungus resistance, life, oto.

Fig 24 Autonetics Hydraulic Components

PRODUCTS

The Power Elements Group has produced electro-hydraulic actuator systems for operating flight controls on the F86, F-100 aircraft, for the X-10, G-26 and G-38 NAVAHO missiles and gimballing actuator systems for rocket engines. The Group has also performed long range research and development work for advanced flight control systems. These programs have stimulated the development of specialized actuator systems to meet broad ranges of environmental conditions, Particular advancement has been made in developing actuators which will operate under ambient conditions from 800 to 1100 deg F and operate at vibration levels up to 25 G’s. The varied design concepts used to meet these unusual and adverse conditions have been highly successful as proven by their operational performance records. These design concepts have been standardized to permit economy of modification to new applications. This standardization and long-range research coupled with constant evaluation of related vendor products makes the Group a valued and reliable system and component source as well as a reservoir of information when coupled to any proposed effort. Information will be provided on request describing products in detail that are available for your application.