LABETLow Altitude Balloon

Experiments in Technology

CPR E 491

ENGR 466

Team IntroductionENGR 466 Team

Brian Walker

Richard George

CPR E 491 Team

Mike Svendsen

Steve Towey

Client IntroductionClient

Iowa State University Space Systems and Controls Lab (SSCL)

Advisor

Matthew Nelson

OverviewClient Statement of NeedsFunctional RequirementsNon-Functional RequirementsDeliverablesProject Decomposition into SubsystemsDesign ConceptsTesting and EvaluationWork Plan

Client Statement of NeedThe SSCL has worked on several iterations of its

LABET platform which is a blimp platform used for both research and for outreach events.  Currently, all of these have been limited to indoor use only which does limit their functionality for some research based projects.  The need is to have an outdoor blimp platform capable of carrying a small payload and able to navigate in calm to light winds

Operating EnvironmentOutdoor usage

Maneuverable in winds up to 10 mph.

Operate in temperatures between -20 and 100 F.

Operate in humidity up to 90%

Functional RequirementsVertical lift capability up to 500 feet

Wireless control/interface up to 1500 feet

Additional payload lift of 7 ounces minimum

System fly time of no less then 20 minutes

Fly and maneuver in up to 10 mph

Balloon lift potential between 80-90% entire system weight

GPS and pressure sensor to determine position

Non-Functional Requirements

Durable and reusable design

Controlled via computer interface

Determine position via computer interface

Project Deliverables Complete balloon system meeting requirements

Operating manuals

Design documentation

Decomposition into Subsystems

Balloon System: Provides majority of lift of the entire system while providing stability.Load Frame: Support for control / sensor systems and payload, while providing balance weight.Propulsion Systems: Includes vertical and horizontal thrust motors, propellers, ESC’s, and main battery use.Electronics: Includes micro-controller, wireless communication, and all sensors.

Software: Includes embedded LABET software, base station communication, and GUI.

Decomposition into Subsystems

Work Breakdown

Design Concepts

Balloon System Design

Balloon Design BreakdownHybrid Latex Blimp System

Envelope1 mil plastic sheetingSeamed to form the blimp shape

BalloonsTwo individual 48” latex balloonsProvides majority of entire system liftEasily replaced and interchangeable

StiffenersCreates a rigid blimp shape in conjunction with balloonsFoam core creates rigid yet light and inexpensive solution

Weight DistributorFoam core bars Distributes weight of frame to envelope and balloonsSeals envelope shut when connected to frame

Final Design Decisions

AssemblyOpen seam prior to connectionStiffeners assembled inside envelopeBalloons placed and blown inside envelope

Visual PresenceAlternating color tip to determine frontSSCL and LABET symbols for added visual

Benefits Breaks down to manageable sizesEnvelope easily repairedParts interchangeable and replaceable

Load Frame ResearchPrevious LABET SystemsLoad Frame Design

Gen. III – Duel Fan ControlGen. IV – Direct Balloon AttachmentGen. V – Propeller Mounting

Material Usage

Material SelectionWeightStrengthDurabilityCost

Load Frame Design

Load Frame Design Breakdown

Cross Foam Core Load FrameFoam Core StructureRigid material yet light and inexpensiveCross design to minimize material

Wooden Motor MountsBass wood for rigidness and strengthBuilt in sheer bracing which connects to frame

Propeller ShroudsProtects propellers from interferenceProvides some thrust funneling

System BoxContains/protects battery and circuitsWeight supported by cross structureRemovable/Replaceable to meet payload changes

Final Design Decisions

StructureCross frame designSpaced separation to maximize strengthDistributes weight through balloon connection

Visual PresenceMinimal in design for weight and lookHides wires and electronics from view

Benefits Material is durable and light for sizeMaterials locally and inexpensively obtainedDirect connection to balloon system

Propulsion – Design Process

Weight Constraints24 ounces

Battery Life Calculations Thrust Calculations

PropulsionDucted Fans vs. Propellers

Brushless Motors vs. Brushed Motors

Propulsion – DesignSelection

s

Thrust Battery Life

Electronics – Design Process

Compile list of sensorsGPS, Rate Gyroscope, Pressure Sensor, Fuel

Gauge, Digital Compass

RF modulePrevious LABETs success with XBee

Electronics – Design Process

PIC vs. Atmel

Selecting PIC ProcessorOperating Voltage – 5.5VUSART – 2 I2C Bus

Timer Counters – 5 Program Memory – 48 KB

Electronics – Block Diagram

Software – Design Process

Development Language and PlatformC++ on Linux

C++ on Windows

Software – Base Station

Advantages DisadvantagesEasy Serial Com OS not as widely usedEasy File I/O OpenGL GUI Extensive experience

Advantages DisadvantagesEasy File I/O Serial Com difficultopenGL GUI Widely available OS

Advantages DisadvantagesCross Platform Serial Com difficultSwing GUI Easy File I/O

Advantages DisadvantagesCross Platform Little ExperienceEasy GUI Built in threading

Java

LabVIEW

Base Station – Frontend

Base Station- Backend

Software - LABET

Structural TestingBalloon System

Seam stress tests

Lift potential test

Assembly/Balloon fill test

Load Frame

Drop test

Motor mount sheer test

Assembly/Balloon fill test

Electronics TestingHardware

Simple test programs

SoftwareCommunication testsGUI interaction testsGround tests

Risks

Hybrid balloon system

Encountering unforeseen setbacks

Little experience with RC equipment

Costs/Resources

Task Breakdown

Current Status

Load frame complete

Balloon complete

Propulsion system integrated

Electronics selected and ordered

Spring Semester Gantt Chart

Questions