ATLAS V GROUND SUPPORT EQUIPMENT DESIGN IMPROVEMENTS

A Thesis

Presented to the faculty of the Department of Mechanical Engineering

California State University, Sacramento

Submitted in partial satisfaction of

the requirements for the degree of

MASTER OF SCIENCE

in

Mechanical Engineering

by

Ryan C. Taylor

SPRING

2015

ii

© 2015

Ryan C. Taylor

ALL RIGHTS RESERVED

iii

ATLAS V GROUND SUPPORT EQUIPMENT DESIGN IMPROVEMENTS

A Thesis

by

Ryan C. Taylor

Approved by:

__________________________________, Committee Chair

Jose Granda

__________________________________, Second Reader

Kenneth Sprott

____________________________

Date

iv

Student: Ryan C. Taylor

I certify that this student has met the requirements for format contained in the University format

manual, and that this thesis is suitable for shelving in the Library and credit is to be awarded for

the thesis.

__________________________, ___________________

Akihiko Kumagai Department Chair Date

Department of Mechanical Engineering

v

Abstract

of

ATLAS V GROUND SUPPORT EQUIPMENT DESIGN IMPROVEMENTS

by

Ryan C. Taylor

Aerojet Rocketdyne (AR) is an aerospace and defense company that specializes in rocket

propulsion. AR manufactures the Atlas V solid rocket boosters that are used on the Atlas V

launch vehicle. These boosters were designed and are in production at the AR Rancho Cordova

facility. During the manufacturing process of these boosters, transportation to and from different

locations throughout the facility is needed. Specially designed tooling and trailers are used, this

equipment is known as Ground Support Equipment (GSE). The GSE is comprised of transporters,

processing carts and trailers. This report will focus on the design improvements of the winch

tensioner that is located on the On Plant Trailer (OPT) and adding an air vent system to the Jeep

section of the Over the Road Transporter (ORT). New design options for each improvement will

be discussed, analyzed and a plan forward will be proposed to implement the design

improvements on the GSE.

_______________________, Committee Chair

Jose Granda

_______________________

Date

vi

TABLE OF CONTENTS Page

List of Figures ....................................................................................................................... viii

Chapter

1. INTRODUCTION……………………………………………………………………….. 1

2. BACKGROUND ................................................................................................................ 3

Manufacturing Process ................................................................................................ 3

Ground Support Equipment ......................................................................................... 4

3. PROBLEM .......................................................................................................................... 9

On Plant Transporter (OPT) Winch Tensioner ............................................................ 9

Over Road Transporter (ORT) Air Ride Vent System .............................................. 10

4. DESIGN APPROACH WINCH TENSIONER ................................................................ 13

OPT Winch Tensioner ............................................................................................... 13

Requirements of Tensioner ........................................................................................ 13

Off-the-Shelf Tensioners ........................................................................................... 14

Analysis of Off-the-Shelf Winch Tensioner .............................................................. 15

Acceptable Test Criteria ............................................................................................ 16

CAD Model Concept of Roller Tensioner ................................................................. 17

5. DESIGN APPROACH AIR RIDE VENT SYSTEM ....................................................... 18

ORT Air Ride Vent System ....................................................................................... 18

Requirements of Air Vent Valve System ................................................................... 18

Off-the-Shelf Air Valves............................................................................................ 19

Analysis of Air Valve in Air System on Jeep ............................................................ 20

vii

Schematic of Air Vent System on Jeep ...................................................................... 21

6. DESIGN REVIEW ........................................................................................................... 22

Design Review of Design Improvements .................................................................. 22

Plan forward ............................................................................................................... 23

Conclusion ................................................................................................................. 23

Appendix A. Design Review PowerPoint Presentation ....................................................... 24

Bibliography ........................................................................................................................... 36

viii

LIST OF FIGURES

Figures Page

1. Atlas V Solid Rocket Booster .................................................................................. … 2

2. Atlas V Cradle Strongback ......................................... ……………………………. 4

3. On Plant Trailer (OPT) ........................ ………….…………………………………. 5

4. Dayton Hydraulic Winch 3VJ75 .................................... …………………………. 6

5. Mounted winch on OPT .................................................. …………………………. 6

6. Current OPT winch tensioner ......................................... …………………………. 7

7. Over the Road Transporter (ORT) ................................. …………………………. 8

8. Atlas Motor Transfer into X-Ray Facility.................... …………………………. 10

9. ORT Air Suspension Diagram ....................................... …………………………. 11

10. Shear Loads on ORT Bolts ............................................ …………………………. 12

11. Spring-loaded Winch Tensioner .................................. …………………………. 13

12. Winch and Roller Tensioner Interfaces ....................... …………………………. 15

13. Grainger Roller Tensioner 3YFH6 .............................. …………………………. 16

14. CAD Model of Roller Tensioner ................................... …………………………. 17

15. Air Suspension Dump System ...................................... …………………………. 20

16. Air Suspension Schematic for Dump Valve ................ …………………………. 21

1

CHAPTER 1

INTRODUCTION

Aerojet Rocketdyne (AR) is an aerospace and defense company that specializes in rocket

propulsion. AR has been designing and manufacturing solid rocket boosters for the last

decade and a half. AR manufactures the Atlas V solid rocket boosters. These boosters

are approximately 67 feet long, 5 feet in diameter, weight about 90,000 pounds and

provide around 375,000 pounds of liftoff thrust. These boosters were designed and are in

production at the AR Rancho Cordova facility.

During the manufacturing process of these boosters, they are transported to and from

different locations throughout the facility. AR has a team of engineers that are

responsible for the transportation of these boosters. These engineers have developed

Ground Support Equipment (GSE), which consists of special trailers, processing carts

and transporters in order to complete the transportation operations.

Over the past decade of operational use of the Atlas GSE, design flaws have become

evident. The objective of this report will be to focus on the design process of improving

two design flaws. New design options for each improvement will be discussed, analyzed

and a plan forward will be proposed to implement the design improvements on the GSE.

2

Figure 1 Atlas V Solid Rocket Booster [1]

3

CHAPTER 2

BACKGROUND

Manufacturing process

There are six major steps in the manufacturing process of the rocket boosters. The first

step is winding the carbon fiber case. The cases are wound in our large case factory

located in the inert manufacturing building. Once the cases are wound, cured and painted,

they are transported to the proof test stand.

Step 2: Proof Test. The cases are proof tested to verify the integrity of the carbon fiber to

see if the case will not fail when exposed to flight loads. The motor is then mated to a

processing cart, which is called a cradle strongback. The cradle strongback is fitted with

wheels, which sit inside a track located on the top rails of the OPT. Upon completion of

the proof test, the cases are transported to the propellant casting building.

Step 3: Cast. The motor case is cast with solid rocket propellant. This operation is done at

the propellant cast building. Once the motor case has been cast with propellant and the

propellant has been cured, the motor is transported to the X-ray facility.

Step 4: X-ray. The live rocket motor is x-rayed to verify that the motor has been

completely casted with propellant, no voids are found and the motor is acceptable for

flight.

Step 5: Final Assembly. The motor is transported to the final assembly building. During

the final assembly, the motor is fitted with the nozzle, all of the mounting hardware,

electronics and the igniters. Upon completion at final assembly, the rocket motor is ready

for flight.

4

Step 6: Prep to Ship. The completed rocket motors have to be shipped all over the US to

support different launches. The motors are transported in a specially designed Over the

Road Transporter (ORT). These transporters have been designed to handle the weight and

the transportation loads that the motor experiences during transportation.

Ground Support Equipment

Cradle Strongback: Processing cart used to set the SRB on during manufacturing and

transportation operations. Strongback has rollers that set inside the guide rails of the OPT

and ORT. See figure below.

Figure 2 Atlas V Cradle Strongback [2]

OPT: On Plant Transporter. Trailer used to move Atlas V SRBs around plant. 3 axle

trailer designed for transporting SRBs in and out of X-ray facility and mating with ORTs.

OPT has a guide rail system that the strongback wheels ride during transfers. The OPT is

also equipped with retractable landing gear that aid in the stabilization and distribution of

weight during motor transfer operations. The hydraulic winch is located at the front of the

5

OPT and mount at an angle as to not protrude past a certain height above the deck. See

figure below for representation.

Figure 3 On Plant Trailer (OPT) [2]

OPT winch and Tensioner: The OPT uses a Dayton 3VJ75 15,000Lbs capacity hydraulic

winch. The winch is equipped with 75 feet of ½-inch cable. The winch is used for motor

transfers on and off the OPT. During a motor transfer onto the OPT, the winch is used to

pull the motor onto the trailer. During a motor transfer off the OPT the winch is used as a

potential break to prevent the motor from free rolling.

6

Figure 4 Dayton Hydraulic Winch 3VJ75 [3]

The winch is mounted to the OPT at a slight angle to stay below a certain height on the

trailer. This mounting position enables certain tooling to pass over the top of the winch

without obstruction.

Figure 5 Mounted winch on OPT

The tensioner is an off-the-shelf unit that was added to the winch in order to keep

pressure on the wound cable when the unit was not in use. The tensioner is comprised of

7

a spring loaded lever arm with a roller on a shaft. The springs apply a force to the lever

arm, which forces the rollers to contact the cable, holding it in place.

Figure 6 Current OPT winch tensioner

ORT: Over the Road Transporter. Trailer is composed of three sections. First section

(Jeep) is a two-axle trailer that mates with the tractor via a king pin and fifth wheel

connection. The second section (Tridem) is a four-axle trailer that contains the motor

compartment. The Tridem also contains the Hydraulic power unit (HPU) which runs the

onboard winch and hydraulic rams for steering the booster dolly (section 3). The Tridem

connects to the Jeep via a kingpin and fifth wheel connection. The last section (booster

dolly) is a three- axle, steerable trailer unit that attaches to the back of the Tridem. This

section is used to steer the ORT in tight turning operations and distribute the overall load

over more axles. See figure below for representation.

8

Figure 7 Over the Road Transporter (ORT) [2]

9

CHAPTER 3

PROBLEM

OPT (On Plant Transporter) Winch Tensioner

Between manufacturing steps 3 and 4, the live rocket motor is transported from the

propellant casting building to the X-ray building. This transportation operation involves

transferring the live rocket motor from the OPT onto the X-ray facility skid. The OPT is

backed up and aligned to the X-ray skid. The motor and strongback are winched off the

trailer and onto the skid. This operation is done in reverse when the motor has completed

the X-ray operations and needs to exit the building. During the transfer operation, the

OPT winch is attached to the motor and is used to trail the motor onto the X-ray skid. The

trailing winch is used as a potential brake should the motor start to roll out of control.

The problem that arises with the OPT winch is during the extension and retraction of the

cable with no tension applied. With no tension, the cable does not wind up/out properly

and can potentially damage the winch/trailer/motor. This potential problem turns into a

safety issue and puts the personnel at risk.

10

Figure 8 Atlas Motor Transfer into X-Ray Facility

In addition to the potential safety risk, manpower time is wasted on reeling up the winch

cable once it has been fully extended. The winch has to be reeled up using 3 operators;

one in the tractor cab operating the hydraulic controls; one operating the manual clutch

lever and ensuring the cable wrap is tight to the winch drum; and the last operator

applying tension to the extended cable. If the winch had a more efficient tensioner, one or

two of the three operators could be eliminated for this time consuming operation.

ORT (Over Road Transporter) air ride vent system

Manufacturing step 6 requires the off plant shipment of the Atlas V SRB (Solid Rocket

Booster). The SRB is loaded into the ORT and shipped off plant. The jeep section of the

ORT was not originally designed with a manual air ride vent system. Only the Tridem

and Booster Dolly have manual venting systems. There are certain motor transfers and

preparation operations during which being able to vent the air on the Jeep section of the

ORT would result in a safer and more efficient operation. Tribal knowledge has taught

11

us that being able to vent each system individually would be very beneficial in preventing

the longevity of the hardware.

Due to the geometry of the air suspension system on the ORT, when the air is vented, the

wheels rotate. This occurs due to the expansion and contraction of the air bags and the

mounting position of the suspension swing arm.

Figure 9 ORT Air Suspension Diagram

When the wheels rotate the entire trailer moves. This presents a problem when the

forward landing gear legs are in the down position and contacting the ground. With the

trailer moving and the landing gear legs being stationary, this creates a large shear force

on the bolts holding the landing gear legs to the trailer. As a result, the bolts are under

constant stress and could fatigue prematurely or fail.

12

Figure 10 Shear Loads on ORT Bolts

13

CHAPTER 4

DESIGN APPROACH WINCH TENSIONER

OPT winch tensioner

The current design of the winch tensioner does not perform the function of keeping the

spool of cable wound tightly around the drum. The current tensioner design is a lever arm

loaded with a spring and the intent is to keep pressure on the wound spool of cable in

order to keep it from un-raveling. This design works well when the cable is static. When

the winch is in motion, the tensioner lacks the strength and ability to maintain the tight

cable position. This design fails when the winch is used as the trailing winch in the

motor transferring operation.

Figure 11 Spring-loaded Winch Tensioner

Requirements of Tensioner

The engineering group that is responsible for the use, maintenance and design of the

OPTs established criteria for the new winch tensioner design.

Be compatible with existing winch configuration

Assist in winding up winch cable

14

Provide tension on winch drum when clutch is released

Simple off the shelf parts/ easily replaceable if needed

No obstruction to winch/ other operations

Height requirement due to tooling interfaces (less than 4.5” above OPT deck

plate)

Off-the-shelf tensioners

Industry has a few options for off-the-shelf type tensioners. These tensioners are more

generic and designed for a wide range of applications. During the time of the original

design of the winch system, the only available off-the-shelf option was the spring-loaded

tensioner that is currently on the winch. This type of tensioner was recommended by the

vendor to use with the winch that was chosen.

A search was done with other winch manufacturers in order to see what is out in industry

as far as winch tensioners and one new concept was found. This concept is a spring

loaded roller guide. There are many different versions of this concept but the basic

function is the same for all. The roller guide mounts to the front of the winch and the

cable passes through the center. The rollers help the cable enter and exit the winch and

prevent the cable from rubbing on any sharp surfaces. The top roller is attached to springs

that apply a force in the downward direction resulting in a clamping force on the cable.

This force creates tension on the cable line preventing it from becoming up-spooled when

not in use.

15

Analysis of Off-the-Shelf Winch Tensioner

Research was done on the roller tensioner in order to find a configuration that would be

compatible with the hydraulic winch that is used on the OPT. The vender that supplies

the Dayton winch also had a version of the roller tensioner guide available as an off-the-

shelf part. An initial engineering and dimensional analysis was done to verify that the

roller tensioner would be the correct size for the winch drum and that the hardware

interfaces would align closely so that with slight modification, the roller could be

mounted to the winch body. The supplier’s technical support staff confirmed

compatibility of the interfaces.

Figure 12 Winch and Roller Tensioner Interfaces [3]

Technical specs such as the spring constant for the tensioner spring and coefficient of

friction of the roller bearings are not available at this point. As a result, tension and

frictional force calculations cannot be done prior to purchasing and testing. The plan

forward is to purchase this type of roller tensioner and perform operational tests to prove

that this concept would function correctly for the applications needed. The roller

16

tensioner that will be purchased for the acceptance testing is item # 3YFH6 from the

Grainger catalog.

Figure 13 Grainger Roller Tensioner 3YFH6 [4]

Acceptable test criteria

Install tensioner on winch, modify if needed.

Perform various cable extensions and retractions with no load on cable

Perform various complete cable wind-ups and observe how cable is wound on

drum

Perform various cable extensions and retractions with working load on cable

Upon completion of the acceptance testing, further modifications will be made if needed.

The springs could be modified to add more or less tension on the cable depending on the

observations of the acceptance testing. The roller bearings could be modified to add more

or less friction on the rollers in order to achieve the optimum tension in the cable.

17

CAD Model Concept of Roller Tensioner

A CAD model was generated in order to integrate the possible new tensioner into the

model assembly of the OPT. In addition, the model will allow modification concepts to

be integrated if the need arises after acceptance testing.

Figure 14 CAD Model of Roller Tensioner

18

CHAPTER 5

DESIGN APPROACH AIR RIDE VENT SYSTEM

ORT Air Ride Vent System

The current design of the ORT has manual vent valves for the air ride systems on the

Tridem and Booster Dolly sections. The vent valves are a three-position air valve. The

three positons of the valve are: Automatic (air bags fill automatically and shut off once

the pre-set height has been reached), Manual (air bags are filled manually), and Dump

(air is vented to atmosphere until system is empty). These three-position air valves make

it possible to raise and/or lower each section of the ORT independently of each other

depending on the given operation.

The Jeep section of the ORT does not have a three- position air valve. The air system is

an independent system that runs off the tow tractor. The air tanks are filled when air is

applied to the pre-set height and then bled off. When the supply air is removed the system

remains full of air and on the current ORT configuration, there is no way to release the

charged air. Due to this design flaw, the need for the air release valve is evident.

Requirements of Air Vent Valve System

The engineering group that is responsible for use, maintenance and design of the ORTs

established criteria as to what the air vent system needed.

2 position air valve (automatic and vent)

Off the shelf parts for availability and maintenance

19

Same vent system configuration as Tridum and Dolly

Ability to vent air system to prevent shear loads on landing gear leg attachment

bolts

Off-the-shelf Air Valves

Industry has a wide variety of off-the-shelf options for air system valves. The original

design intention of these transporters was that all of the parts would be easily available

and cheap to purchase. The idea was that if a failure was to occur in the field, parts could

be found and replaced with little to no impact to the schedule. The original design

intention needs to be supported with the new air valve, which denotes that an off-the-

shelf unit would be the optimum choice.

Haldex is a company that manufactures and distributes air valves for air ride systems.

This company supplies the other air valves that are currently in use on the ORT. A

technical evaluation was done on the Jeep air ride system with the valve experts at

Haldex and they recommend a valve and dump system for this application. The valve that

was recommended is a two position (inflates or exhausts) height control valve, part

number 90555106. This is a relatively new valve that replaces the old height control

valve 90554271. In addition, a manual switch and bracket were also recommended to use

with the 90555106 valve.

20

Figure 15 Air Suspension Dump System [5]

Analysis of Air Valve in Air System on Jeep

Research was done on possible impacts this valve could have on the Jeeps air suspension

system. It was concluded that by adding the valve to the air suspension system, there will

be no negative impacts on the system. This is a two positon valve; inflate to automatic

21

height or release air, so there is no potential for overinflating the air bags. The valve will

remain in the automatic fill position most of its life. The valve will be used to vent the

system for operations that require it to be done. In a dynamic scenario, the valve will be

placed in the automatic position, exactly how the other two systems are configured for

road transportation. Procedural check offs will be implemented into the process

procedure to ensure the valve is in the correct position for road transportation.

Schematic of Air Vent System on Jeep

A schematic was created to show where in the air suspension system the new height

control valve would be located. The Height control valve will be installed upstream of the

suspension control valve and downstream of the pressure protection valve. This position

will allow the air suspension to have the air released manually.

Figure 16 Air Suspension Schematic for Dump Valve

22

CHAPTER 6

DESIGN REVIEW

Design Review of Design Improvements

A PowerPoint presentation was created summarizing the problems, proposed solutions,

and plans forward for the design improvements. This presentation is located in Appendix

A. The presentation was given to the lead tool designer, lead GSE engineer and other

supporting engineers that work with the day-to-day operations of the GSE. The problems

with the current designs were discussed and analyzed. The criteria for the new designs

were better defined and the plan forward for each improvement was accepted.

Possible issues arose during discussion with the winch tensioner roller improvement. One

possible issue has to do with when the winch is in the trailing configuration on a motor

transfer operation into the X-ray facility. The winch lets out the cable to provide slack for

the motor to move in the opposite direction. However, when the winch provides slack,

the cable may not be able to pass through the roller tensioner, due to the clamping force

on the cable, until the motor applies tension on the cable. This would result in the motor

pulling the excess cable out of the roller tensioner, which could impose impulse loads on

the winch, tensioner and cable.

The issue explained in the previous paragraph and other issues that arise with both

design improvements will be addressed during the acceptance testing of the hardware.

Modifications and adjustments will be done in order to meet the criterion that has been

laid out for each improvement.

23

Plan Forward

The plan forward for the winch tensioner:

Purchase winch tensioner from Grainger and install on OPT

Perform various acceptance tests to prove tensioner will perform for the

operations needed

Review acceptance tests results and modify tensioner if needed.

Purchase and install tensioners for all OPTs

The plan forward for the air ride vent system:

Purchase and install vent system on ORT Jeep

Perform functional/acceptance tests on vent system

Evaluate function/acceptance tests results and modify system as needed

Install vent system on all ORT Jeeps

Conclusion

The objective of this report was to focus on the design process of improving two design

flaws that have been identified with the Atlas GSE. New design options were discussed,

analyzed and a plan forward on the implementation of these improvements has been

proposed. The design and analysis phases have been completed and with approval from

the Atlas Program Management Team, these improvements will be implemented and

ultimately improve the ground support operations of the Atlas V Solid Rocket Boosters.

24

APPENDIX A

Design Review

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BIBLIOGRAPHY

[1] Aerojet Rocketdyne website (rocket.com)

https://www.rocket.com/article/aerojet-delivers-50th-flight-ready-solid-rocket-

booster-united-launch-alliance

[2] Aerojet Rocketdyne official GSE technical drawing

[3] Dayton Hydraulic Winch 3VJ75 user manual

http://www.grainger.com/ec/pdf/Dayton-Hydraulic-Winch-3VJ75-OIPM.pdf

[4] Grainer website, online catalog

http://www.grainger.com/product/B-A-PRODUCTS-CO-CABLE-TENSIONER-

ROLLR-GUIDE-

3YFH6?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/3YFH6_

AS01?$smthumb$

[5] Haldex Product Catalog (Haldex.com)

http://epi.hbsna.com/products/product.asp?msi=0&sid=FBB3BE77AFBB4E499C

F708AA5E3B6E7A&pf_id=90555106&dept_id=2629