Electrical Subsystem Design - EDGE



1. Product Introduction and Planned Function 1

1. Mission Statement 1

2. Product Description 1

3. Stakeholders 2

4. Scope Limitations 2

5. Market Potential 3

6. Market Competitors 3

7. Project Deliverables 4

2. Concept Development 5

1. Weather Resistance & Covers 5

2. Ramps 6

3. Boxes 7

4. Fuel Containment 8

5. Trailer Type 9

6. Lift Mechanism 11

1. Elevated Deck Trailer 11

2. Four Bar Linkage Lift Platform 12

3. Parallel Lift Platform 12

4. Crane 13

5. Scissor Lift Platform 13

6. Cumulative Concept 14

7. Launch Platform & Landing Platform 14

1. Flat Deck 15

2. Winged Flat Deck 15

3. Bilco Door Deck 15

8. Tie Down Systems & Attachment Points 16

9. Rotor Blade Vibration & Protection Packaging 16

10. Payload Vibration Isolation 17

11. Helicopter Suspension 18

12. Electrical Sub-System Development 18

3. Feasibility Assessment 24

1. Weather Resistance & Covers 26

2. Ramps 26

3. Boxes 27

4. Fuel Containers 28

5. Trailer Type 28

6. Lift Mechanism 28

7. Launch Platform 29

8. Crane 29

9. Tie Down Systems 30

10. Tie Down Attachment Points 30

11. Power Converter Module 30

12. Battery Charging Module 31

4. Design Objectives and Criteria 32

1. Weather Resistance & Covers 32

2. Ramps 32

3. Boxes 33

4. Fuel Containment 34

5. Trailer Type 35

6. Lift Mechanism 36

7. Launch Platform 36

8. Crane 37

9. Tie Down System 38

10. Tie Down Anchor Points 38

11. Rotor Blade Vibration & Protection Packaging 38

12. Payload Vibration Isolation 39

13. Power Supply Adapter 39

14. Power Converter Module 40

15. Battery Charging Module 40

16. Wire Gauge Selection 41

5. Analysis of Problems & Synthesis into the Design 42

1. Vibrations Analysis 44

2. Structural Analysis 46

1. Fuel Containment Structure 46

2. Fuel Tank Support Beams 47

6. Preliminary Design 49

1. Preliminary Drawing Packages 50

2. Bill of Materials, Supplier Identification, & Pricing 51

3. Electrical Systems Layout 52

1. Electrical Subsystems Design 52

7. Matlab Vibration Simulation 53

8. Future Plans 55

1. Schedule 56

9. Appendix

1. Feasibility Pugh Charts (Simple and Weighted)

1. General Project Concerns A1

2. Waterproofing A2-A3

3. Ramps A4-A5

4. Boxes A6-A7

5. Fuel Containers A8-A9

6. Trailer Type A10-A11

7. Lift Mechanism A12-A13

8. Launch Platform A14-A15

9. Crane A16-A17

10. Holding Mechanism A18-A19

11. Attachment Points A20-A21

12. Electrical Converter A22-A23

13. Electrical Charger A24

2. Concept Sketches B1-B10

3. Vibrations Output Graphs

1. Payload Acceleration With Full Fuel Load C1

2. Payload Displacement With Full Fuel Load C2

3. Payload Acceleration Without Full Fuel Load C3

4. Payload Displacement Without Full Fuel Load C4

4. Electrical Resistance Tables D1

5. Senior Design II Schedule E1-E2

6. Vendors F1

1. Product Introduction and Planned Function

1.1. Mission Statement

The future of warfare will be much different than it is now. Unmanned air and ground support vehicles are currently in development to assist and possibly lead assaults on enemy forces. Airborne sensor platforms currently being developed are the future eyes in the sky for military commanders and will aid in reconnaissance and targeting. Continuous surveillance of enemy forces will be possible without risking the safety of soldiers and pilots once developing technology takes flight over the battlefield.

1.2. Product Description

As defined by DARPA (Defense Advanced Research Projects Agency) “the DP-5X program will provide a flight-ready, tactically transportable, vertical take-off and landing unmanned air vehicle (VTOL UAV) to integrate with a gimbaled payload for technology demonstration of the JIGSAW sensor package. The UAV will be employable by a two person team and deployable in a single high mobility multipurpose wheeled vehicle (HMMWV), also known as a Humvee. It will provide lift for a 75 lb payload with 6 hours endurance, 100 knots cruising speed, with nap of the earth agility. Multi-mission capability and modularity will allow the DP-5X to rapidly integrate additional payloads for sensing, communications, and target effects”. [1]

The project team will develop a system that will transport this UAV behind the HMMWV in combat situations and provide all necessary ground support.

1.3. Stakeholders

Dragonfly Pictures are the creators of unmanned autonomous vehicles (UAVs) which it has been developing since the early 1990’s. Currently in development is the DP-5X which is based around an Advanced Multi-Mission Platform (AMMP) and is funded under DARPA which is the central research and development organization for the Department of Defense. The 5X has performed several tests flights and is nearing autonomous flight capability, completing the original design intent of the craft. Dragonfly Pictures Incorporated is only one of the companies funded under DARPA that are competing to have the most advanced UAV, therefore careful consideration of time, funding, development, and efficiency are key.

1.4. Scope Limitations

Initially the scope was set to design a carrier kit for the back of an HMMWV and off road trailer that will load, unload and provide secure transport over rough terrain at 65 mph for the DP-5X.  Design lift handles and tie downs. Adhere to military specifications on lifting and carrying, with two soldiers maximum.  Provide electrical interface from HMMWV for charging and ground support equipment. 

As the project progressed, the scope continued to grow as additional sponsor requirements were suggested. Dragonfly Pictures is currently seeking to develop a deployment system for the DP-5X so that it may fill the immediate need of UAVs that do not require a runway. The proposed system for deployment is a single DP-5X in a trailer which will allow sustained flight for long periods of time, and contain all necessary equipment for a seventy two our mission hour mission . The trailer must serve several purposes. Primarily it will allow safe transport and protection from environmental factors such as rain, sand, mud, and snow.

It was determined that the trailer will be in combat for three days. Therefore, the trailer will also house enough fuel to provide continuous coverage over target for seventy two hours while located in remote areas. There will be compartment storage for rotor blades, payloads, and support equipment. The trailer will also utilize a crane to load/unload the UAV, mount, dismount and maneuver payloads, and aid in field service when required.

1.5. Market Potential

The primary market for the VTOL UAVs is currently the United States Department of Defense. The ability to launch and recover the UAV without the requirement of a runway is a great advantage to current UAV currently deployed in the US forces. As the development of VTOL UAVs is advanced, and proven there is a greater chance of creating a secondary market. If these systems become cost effective, they could be seen patrolling areas where cameras are not present in the commercial surveillance industry. The application could be utilized in the media industry to acquire daily traffic reports, crop dusting, and coastguard search and recovery missions.

1.6. Market Competitors

The military currently uses small unmanned aircraft for surveillance and reconnaissance. Some designs require bulky, long, trailers that must be towed along with the convoy to launch these aircraft for situations in which a runway is not available. This is one of the main advantages of VTOL systems. In order to break into and replace the current applications the DP-5X must prove to meet all of its expectations.

1.7. Project Deliverables

Project Qualifiers (12/7/2004):

• Modified Trailer That DPI Purchases for Project

• Concept Sketches of Alternatives with Pros & Cons

• Preliminary Design of Fully Modified Trailer

• Complete Design Report

• Stress Analysis of Critical Components

• Stresses and Loads on Aircraft During Landing and Transport

• Finite Element Analysis of Critical Components

• Latch Design

• Suspension Design

• Video Animation of Landing, Dismounting, Offloading, Loading, and Landing

• Operational Plan for Using the Trailer in Accordance to CONOPS (Concept of Operations)

• Preliminary Design of HMMWV Modification

• Modified HMMWV That RIT Gets From National Guard on Loan

• Production Cost Estimate and Manufacturing Plan

• Demonstration of Trailer and/or HMMWV at DPI with S/N 101 at 65 MPH Over the Back 40

Project Winners

The project scope was narrowed to address the main concerns which are:

• Concept sketches of alternatives with pros and cons

• Preliminary design of trailer modification

• Modified trailer that DPI purchases for RIT project

• Stress analysis of critical components

• Stress analysis of aircraft/landing interface

• Finite element analysis of critical components

2.0 Concept Development

Based on the requirements for the deployment system and the limited area of the trailer deck size, much time and effort was necessarily spent brainstorming different configurations and concepts. Keeping the overall goal of the system in mind, while adhering to weight and size constraints proved to be a challenging experience for our team. Each week, new concepts were developed, replacing or building upon earlier concepts.

2.1. Weather Resistance & Covers

The method of waterproofing used is heavily contingent on the overall design chosen for the trailer. Early designs of the trailer called for structural cabinets to extend above the rotor height of the helicopter. On top of this structural surface, a rigid tonneau cover could be mounted much like that on the back of a pickup truck. The design currently being used does not have structural cabinets extending above the height of the rotor because of excessive weight issues, and thus a choice had to be made: Which method for waterproofing will prove most effective, while limiting the intrusion into future designs, keeping important factors of time, weight, and cost in mind? With this considered, there were two main choices.

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The first method was that of the concept that originated when the structural cabinets extended to the height of the helicopter rotor. A steel frame would be built in the place that the cabinets would have sat, and on top of that, the tonneau cover would be mounted. While this would have allowed for a more simplified method of covering the trailer, it had some major drawbacks.

• Additional weight

• Additional construction time

• Added cost

The second method was simply using a canvas-type of cover that would be thrown over the top of the trailer to keep water and other elements off of the sensitive equipment underneath. The main drawbacks of this method are that it lacked structure to keep it from lying on the equipment underneath water drainage. A compromise between the two choices proved to be most effective. A lightweight frame would be built using round tubing as supports. This frame would support the canvas cover keeping it from lying on the equipment underneath and give it the necessary structure to shed water. Since this design uses a limited number of parts, it saves time, cost, and weight, not inhibiting a future platform design. This design facilitates a future launch/recovery system to easily be added at a latter

2.2. Ramps

A method of loading and unloading the aircraft has been paramount since the beginning of the design process. Much like waterproofing, this concept is heavily contingent upon the final design chosen. Earlier designs had considered a possible tailgate or lifted platform that would double as a ramp for loading and unloading. After the design became finalized, it became apparent that there was only a single “best” choice for loading and unloading the helicopter. A fundamental method such as ramps has proven the most effective way to load and unload without having to depend on an external source of energy that may become unusable should failure occur. The concept of using ramps has been chosen because of both its simplicity and its versatility. Earlier methods such as that of a folding tailgate or lift platform/ramp have the following limitations;

• Need an external power source for functionality

• Limit use to only the trailer (helicopter on hummer or other vehicle would have to be unloaded by other means)

2.3. Boxes

            There were 3 separate concepts when considering the best box for storing the tools, blades, and gear, and payload.  Custom boxes were used as the baseline. They were compared to a pre-built unit that was already being manufactured and also boxes that the team would have to design and produce from the ground-up.  The winner in this case was Custom Boxes that would be designed and built by a vendor according to the team’s specifications.  The main reason that this concept was pointed to was because customization was an important issue, because space was limited and the boxes needed to be integrated into the fuel compartments, while being able to support a launch platform in the future.  Lead-time is a large concern and custom boxes do take slightly longer to get than pre-made boxes, custom boxes were preferred because it is essential that the boxes conform to the dimensions the group has designed around.  No pre-made boxes were found to do this, therefore, the group agrees with the chart’s decision.

2.4. Fuel Containment

The transportation system for the DP-5X autonomous aircraft is required to carry fuel for several hours of operation, in addition to tools, spare parts, and a detachable payload. Due to the large size of the aircraft and the multitude of accessory items, there is very little room in the loading plan to carry the necessary volume of fuel. To address the issue, a design was created that incorporated the fuel tanks into two bays on either side of the trailer, which also provide support for tool and supply boxes. This solution, however, presented another problem of its own. The spaces where the fuel tanks are destined to be placed are interrupted by the wheel wells of the trailer. As a result, typical prefabricated containers would be unsuitable for this application.

The solution for this new found design problem began with a survey of commercially available products. Knowing a few desired characteristics of the fuel system, anything that looked like it might be applicable was considered and compared. As the list of options grew, it became apparent that some ideas were better than others, often due to features that had not been initially considered as requirements.

As the transportation system is intended for the military, initial search efforts were focused towards pre-existing military systems. However, as with many military destined products, specifications and other general information on such items were scarce at best. The one option that was gleaned from this particular search was the collapsible fuel bladder. The world of automobile racing, however, provided several promising solutions, which are specifically designed to be used in punishing and dynamically demanding environments. Containers designed for racing applications are generally referred to as fuel cells, and come in rigid and semi-rigid varieties. Additionally, there are baffles to prevent the motion of fuels while the vehicle is maneuvering which in turn ill prevent foaming. The fuel system design turned out to be far less mathematical in nature, than it was a matter of fitting simple qualitative objectives, and the end product was chosen accordingly. The final fuel storage degign configuration consists of four separate bladders mounted in enclosed sheeted frames at the four corners of the trailer. This configuration keeps the load low and distributed, while provided the required volume of fuel.

2.5. Trailer Type

Brainstorming for the trailer began with the sponsor’s recommendation of using the Silver Eagle brand trailer. Silver Eagle is a large supplier that currently has government contracts to build trailers for the military. The first mode of information was simply finding the company on the internet. Extensive information was provided that included GVW, surface area, and different trailer types.

With many different trailers to choose from the group had to figure out which trailer would suit the goals of the project the best. Silver Eagle offered three light tactical trailers (LTT) that were the of team’s main consideration – LTT-F, LTT-FE, and LTT-HC. See technical data package. All trailers were similar in that they are based on the same suspension and therefore can hold the same weight of cargo. The LTT-F and LTT-FE are both flat-deck trailers, but the LTT-FE has a deck which is three feet longer than the LTT-F. The LTT-HC is the same length as the shortest trailer, but is constructed with pre-built sides that contain cargo, and a tailgate. Price quotations for each trailers were analyzed with a negligible difference in price ( ................
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