221640main EDC Spacecraft Structures

7/28/2019 221640main EDC Spacecraft Structures

1/78

NASA Engineering Design Challenges

Spacecraft Structures

National Aeronautics and Space Administration

EP-2008-09-121-MSFC

Educational Product

Educators Grades 6


2/78

Cover Illustration:

NASA Ares I and Ares V Launch Vehicles

NASA artist conceptions.


3/78

NASA Engineering Design Challenge: Spacecraft Structures 2007 i

Table o Contents1. Overview

....................................................................................................

1

2. How to Use This Guide.............................................................................. 3

3. National Science Education Standards ..................................................4

4. Math Connections ..................................................................................... 6

5.Thinking Skills........................................................................................... 7

6. Background

The Ares Launch Vehicles ........................................................................... 8

Spacecrat Structures.................................................................................. 9

7.Teacher Preparation

Required Materials......................................................................................13

Build the Launcher ................................................................................... 15

Build the Rockets .....................................................................................17

Practice Launching a Rocket....................................................................17

Prepare the Materials or the Classroom..................................................18

Teaching Strategies or an Engineering Design Challenge.......................19

Helping Students Understand the Design Process .................................. 21

8. Classroom Sessions

Session 1: Introducing the Challenge and Getting Started ...................... 22

Session 2: Design 1 ..................................................................................27

Session 3 and 4: Designs 2, 3, 4, and 5 ...................................................31

Session 5: Construct a Storyboard/Poster...............................................34

Session 6: Student Presentations ............................................................ 36

Linking Design Strategies and Observations to Science Concepts.........37

9. Modifcations and Extensions .............................................................. 44

10. Resources...............................................................................................

46

11. Masters ................................................................................................... 49

Flier or Parents

Handouts/Transparencies

Recording Sheets


4/78

ii NASA Engineering Design Challenge: Spacecraft Structures 2007

*The Ares Engineering Design Challenges use Traditional U.S. units o measure

as the standard. Metric units ollow in (parenthesis). In cases when a given

ormula is traditionally calculated in metric units, or mathematical correctness,

it is presented in that manner.

NOTE: The Ares vehicles are a very preliminary confguration and will be subject

to change as the design progresses.

Authors

Nick Haddad, TERC

Harold McWilliams, TERCPaul Wagoner, TERC

Subject Matter Experts & Reviewers

Bob Bender: MSFC, Spacecrat & Vehicle Systems Department, QUALISJe Finckenor: MSFC, Spacecrat & Vehicle Systems Department, NASAKristy Hill: MSFC, Academic Aairs Oce, WILL Technology Inc.Bill Pannell: MSFC, Spacecrat & Vehicle Systems Department, NASATwila Schneider: MSFC, Ares Projects Oce, Schaer Corporation

Design and Layout

Sandra Schaer: Schaer LaCasse Design, Somerville, MA

Graphics

Ted Allbritton: MSFC, UNITeS Technical Publications & Illustrations, TRAXMelissa Higdon: MSFC, UNITeS Technical Publications & Illustrations, TRAXJennie Mitchell: MSFC, UNITeS Technical Publications & Illustrations, TRAX

Ares I and VNASA artist conceptions

Editor

Regina Garson: MSFC, Ares Projects Oce, UNITeS

NASA explores for answers that power our future.

www.nasa.gov
http://www.nasa.gov/http://www.nasa.gov/


5/78

NASA Engineering Design Challenge: Spacecraft Structures 2007 1

NASA Engineering Design

ChallengesSpacecrat Structures

1. Overview

Space TransportationNASA Engineers at Marshall Space Flight Center, along with their partners atother NASA centers, and in private industry, are designing and beginning todevelop the next generation o spacecrat to transport cargo, equipment, andhuman explorers to space. These vehicles are part o the Constellation Program,which is carrying out a bold vision o human space exploration. The programincludes a crew exploration vehicle and the spacecrat to carry the crew to theMoon and later to Mars. The NASA Authorization Act o 2005 directs NASA toestablish a program to develop a sustained human presence on the Moon, whichwill serve as a stepping stone to urther exploration o Mars and other destina-tions. This design challenge ocuses on the Ares amily o rockets, which willreplace the Space Shuttle in the task o putting people, satellites, and scienticexperiments into space.

Connect to Engineering and ScienceThe Engineering Design Challenges connect students with the work o NASAengineers by engaging them in similar design challenges o their own. With somesimple and inexpensive materials, you, the teacher, can lead an exciting unit thatocuses on a specic problem that NASA engineers must solve and the processthey use to solve it. In the classroom, students design, build, test, and revisetheir own solutions to problems that share undamental science andengineering issues with the challenges acing NASA engineers.

The Design ChallengeYou will present students with a challenge: Build a model thrust structure (theportion o the structure that attaches the engine to the rest o the spacecrat)that is as light as possible, yet, strong enough to withstand the load o a launchto orbit three times. See Figure 1.1. Students rst determine the amount oorce needed to launch a model rocket to 3.3 eet (1 meter), which representslow Earth orbit. Then they design, build, and test their own structure designs.They revise their designs over several design sessions, trying to maintain orincrease the strength and reduce the weight o their structure. They documenttheir designs with sketches and written descriptions. As a culmination, studentscompile their results into a poster and present them to the class.

Figure 1.1. Thruststructure model.

Figure 1.2. Example launch

testing station.


6/78

2 NASA Engineering Design Challenge: Spacecraft Structures 2007

MaterialsYou will need a ew simple and inexpensive materials:

Craftsticks.

Dowels.

Gluegunsandhot-meltglue.

Corrugatedcardboard.

35mmlmcanisters.

1-litersodabottles.

2-litersodabottles.

25-50pounds(11-23kilograms)ofsand.

Asturdyclothbagtoholdthesand.

Brasstubing.

Packagesealingtapeabout2incheswide.

4-ouncepapercups.

Time RequiredThe design challenge can be carried out in six 45-minute class periods, but youcould easily extend it or twice that length o time. We provide some ideas orextensions at the end o the guide.

You will need to invest 4-8 hours gathering the materials, building the test stand,trying out your own designs, reading the guide, and preparing the classroom.

Value to StudentsThese activities help students achieve national goals in science, math, and think-ing skills. In the pilot testing o the design challenge, students embraced thedesign challenge with excitement. This activity will provide your students theopportunity to solve a challenge based on a real-world problem that is part othe space program and to use creativity, cleverness, and scientic knowledgein doing so. During these activities, students will have many opportunities tolearn about orces, structures, and energy transer. The culminating activity givesstudents an opportunity to develop their presentation and communication skills.

Student Research OpportunitiesThe "Resources" section o this guide includes many web sites where students

can obtain additional inormation.

Parent InvolvementThe "Masters" section o this guide includes a reproducible fier to send home toinorm parents about the activity. It includes suggested activities students andparents can do at home together.

SaetyThese activities meet accepted standards or laboratory science saety.


7/78


2. How to Use This guideThis guide is divided into several sections: National Science Education Standards.

Math Connections.

Thinking Skills.

Background Material.

Preparation or the Challenge.

Day-by-day Procedures.

Extensions.

Resources.

Masters.

National StandardsI you have questions about how this activity supports the National ScienceEducation Standards, Math Connections, or Thinking Skills, read those sectionsrst. Otherwise, reer to those sections only as you need them.

Suggested Order o ReadingFirst, skim through the entire guide to see what is included.

Next, read through the Classroom Sessions. Give special attention to the lastpart, Linking Design Strategies and Observations to Science Concepts, onPage 37. This gives explicit suggestions on how to help students understand

the science in their designs. Review this section again ater you start classroomwork with your students.

Be sure to read the last two sections in the Teacher Preparation section:Teaching Strategies or an Engineering Design Challenge, on Page 19, andHelping Students Understand the Design Process, on Page 21. These will helpyou understand what is distinctive about an Engineering Design Challenge andhow your students can get the most out o it.

When you understand the session-by-session fow and the pedagogicalapproach on which it is based, read the Background section. This will provideyou with inormation you will want to have in mind to set the stage or studentsand to link their classroom work with the work o NASA engineers. It ocuses onone o the challenges aced by NASA engineers in developing a reusable launch

vehicle: Spacecrat Structures.Further resources or you and your students can be ound in the Resourcessection on Page 46.

The reproducible masters you need are in the Masters section at the end othe book.

Finally, read the remainder o Teacher Preparation to nd out how to prepareyour classroom and yoursel to conduct the Engineering Design Challenge.It contains saety guidelines, lists o materials, suggestions or organizing theclassroom, and teaching techniques.


8/78


3. National Science Education

StandardsThis Engineering Design Challenge supports the ollowing Content Standardsrom the National Research Councils National Science Education Standards.

Science as InquiryAll students should develop abilities necessary to do scientic inquiry.

Fundamental Abilities and Concepts Studentsshoulddevelopgeneralabilities,suchassystematicobservation,

making accurate measurements, and identiying and controlling variables.

Studentsshoulduseappropriatetoolsandtechniques,includingmathematics, to gather, analyze, and interpret data.

Studentsshouldbasetheirexplanationonwhattheyobserved,providing

causes or eects and establishing relationships based on evidence.

Studentsshouldthinkcriticallyaboutevidence,decidingwhatevidence

should be used, and accounting or anomalous data.

Studentsshouldbegintostatesomeexplanationsintermsoftherelation-ship between two or more variables.

Studentsshoulddeveloptheabilitytolistentoandrespecttheexplana-tions proposed by other students.

Studentsshouldbecomecompetentatcommunicatingexperimentalmethods, ollowing instructions, describing observations, summarizingthe results o other groups, and telling other students about investigations

and explanations. Studentsshouldusemathematicsinallaspectsofscienticinquiry.

Mathematicsisimportantinallaspectsofscienticinquiry.

Technologyusedtogatherdataenhancesaccuracyandallowsscientiststo analyze and quantiy results o investigations.

Scienticexplanationsemphasizeevidence.

Scienticinvestigationssometimesgeneratenewproceduresforinvestiga-tion or develop new technologies to improve the collection o data.

Physical ScienceAll students should develop an understanding o motions and orces.

Fundamental Concepts and Principles, Grades 5-8 Anobjectthatisnotbeingsubjectedtoaforcewillcontinuetomoveata

constant speed and in a straight line.

Ifmorethanoneforceactsonanobjectalongastraightline,thenthe

orces will reinorce or cancel one another, depending on their directionand magnitude. Unbalanced orces will cause changes in the speed ordirection o an objects motion.

Energyistransferredinmanyways.

Students respond positively to the

practical, outcome orientation o

design problems beore they are

able to engage in the abstract,

theoretical nature o many scientifc

inquiries.

National Science EducationStandards, National Research Council

Complete text o Benchmarks

or Science Literacy

http://www.project2061.org/publi-

cations/bsl/online/bolintro.htm

Complete text o the National

Science Education Standards

http://books.nap.edu/openbook.

php?isbn=0309053269
http://www.project2061.org/publications/bsl/online/bolintro.htmhttp://www.project2061.org/publications/bsl/online/bolintro.htmhttp://books.nap.edu/openbook.php?isbn=0309053269http://books.nap.edu/openbook.php?isbn=0309053269http://books.nap.edu/openbook.php?isbn=0309053269http://books.nap.edu/openbook.php?isbn=0309053269http://www.project2061.org/publications/bsl/online/bolintro.htmhttp://www.project2061.org/publications/bsl/online/bolintro.htm


9/78


Fundamental Concepts and Principles, Grades 9-12 Objectschangetheirmotiononlywhenanetforceisapplied.Lawsof

motion are used to precisely calculate the eects o orces on the motiono objects. The magnitude o the change in motion can be calculated usingthe relationship F=ma, which is independent o the nature o the orce.Whenever one object exerts a orce on another, a orce equal in magnitudeand opposite in direction is exerted on the rst object.

Science and TechnologyAll students should develop abilities o technological design.

Fundamental Concepts and Principles1. Design a solution or product.

Considerconstraints.

Communicateideaswithdrawingsandsimplemodels.

2. Implement a design.

Organizematerials.

Planwork.

Workascollaborativegroup.

Usesuitabletoolsandtechniques.

Useappropriatemeasurementmethods.

3. Evaluate the design.

Considerfactorsaffectingacceptabilityandsuitability.

Developmeasuresofquality.

Suggestimprovements.

Trymodications.

Communicatetheprocessofdesign.

Identifystagesofproblemidentication,solutiondesign,implementation,

evaluation.

The challenge satises the ollowing criteria or suitable design tasks:

Welldened,notconfusing.

Basedoncontextsimmediatelyfamiliartostudents.

Hasonlyafewwell-denedwaystosolvetheproblem.

Involvesonlyoneortwoscienticconcepts.

Involvesconstructionthatcanbereadilyaccomplishedbystudents,

not involve lengthy learning o new physical skills, and not require time-consuming preparation or assembly.

All students should develop understandings about science and technology.

Differencebetweenscienticinquiryandtechnologicaldesign.

Technologicaldesignshaveconstraints.

Technologiescost,carryrisks,andprovidebenets.

Perfectlydesignedsolutionsdonotexist;engineersbuildinback-upsystems.

Through design and technology

projects, students can engage in

problem-solving related to a wide

range o real-world contexts. By

undertaking design projects, stu-

dents can encounter technology

issues even though they cannot

defne technology. They shouldhave their attention called to the

use o tools and instruments in

science and the use o practi-

cal knowledge to solve problems

beore the underlying concepts are

understood.

Benchmarks or

Science Literacy, AAAS


10/78


4. Math ConnectionsThis Engineering Design Challenge oers the opportunity to integrate a variety omath skills*, described in the ollowing table. Some o the listed applications arepart o extension activities.

Skill Application

Perorming operationswith decimal numbers

Mass o structure, quantitieso materials

Rounding Rounding mass o structure to thegram, tenth o a gram, etc.

Calculating averages Calculating average, mean, median,mode, or range or all designs by oneteam, or or the entire class

Graphing Creating line graphs, bar graphs, circlegraphs, or scatterplot o structuremass versus launch successGraphing number o successullaunches vs. mass o the structureGraphing number o successullaunches vs. size (width, length, diam-eter) o the structure

Measuring percentage improvement Comparing designs by one team,calculating improvement or the entireclass

Calculating ratios Determining the relationship between

the quantity o materials used andthenumberofsuccessfullaunches;between the mass dropped and thelaunch height

Using ormulas Calculating gravitational potentialenergy, PE = mgh and kinetic energy,KE = 1/2 mv2

Using a budget See the extension activity: Limitingdesigns by cost

*The Ares Engineering Design Challenges use Traditional U.S. units o measureas the standard. Metric units ollow in (parenthesis). In cases when a givenormula is traditionally calculated in metric units, or mathematical correctness,it is presented in that manner.


11/78


5. Thinking SkillsThis Engineering Design Challenge provides an opportunity to assess studentsdevelopment o critical thinking skills in a context in which these skills areapplied throughout the task. Students are oten asked to perorm critical think-ing tasks only ater they have mastered such lower-level thinking skills as makingsimple inerences, organizing, and ranking. In this learning activity, various levelso thinking skills are integrated. The ollowing rubric is designed to assist you inassessing student mastery o thinking skills.

Cognitive Memory Skills1. Students accurately measure the drop height and compute the average

height.

2. Students observe a design beore testing and pick out the key eatures.

3. Students observe a model during and ater testing and document preciselywhat happens to the model.

4. Students record observations and organize data so that they can beexchanged with others and reerred to later.

Structuring, Organizing, Relating Skills5. Students can classiy designs.

6. Students can rank designs according to various criteria, i.e., strength, mass.

7. Students can create diagrams, charts and graphs o the results.

8. Students can visualize relationships such as part-whole, cause-eect.

9. Students can interpret such inormation as test results and designdocumentation.

10. Students can compare and contrast dierent design solutions.

Convergent and Generalizing Skills11. Students can demonstrate that they understand the challenge.

12. Students can draw conclusions and generalize.

13. Students can converge on a solution by choosing rom alternatives.

Divergent Thinking Skills14. Students can apply ideas and concepts o motions and orces to their

designs.

15. Students can make inerences and predictions about the perormanceo a design.

16. Students can invent and synthesize a solution.17. Students can devise an experiment to test a particular theory.

18. Students can balance trade-os between cost, quality, saety, eciency,appearance, and time.

Evaluation Skills19. Students can evaluate designs based on given criteria.

20. Students value new knowledge.


12/78


6. Background

The Ares Launch VehiclesOn July 20, 1969, Neil Armstrong and Buzz Aldrin became the rst humans to set oot

on the Moon. They arrived there in a lunar lander, which had been propelled into orbit

around the Moon as part o the Apollo 11 space fight. NASA now has plans to return

humans to the Moon and eventually to Mars. NASA is designing new spacecrat to

carry them there. These spacecrat are known as the Ares launch vehicles.

NASA Engineers at Marshall Space Flight Center are currently developing the launch

vehicles or the next generation o space travel. The Ares I crew launch vehicle will

deliver the Orion crew exploration vehicle into Earth orbit. Astronauts in Orion can then

dock with the International Space Station, or rendezvous with the Altair lunar lander,

put into orbit by the Ares V launch vehicle or transport to the Moon.

Ares I is a two-stage rocket. (See Figure 6.1.) The rst stage is a reusable solid rocket

booster (RSRB) similar to the boosters o the Space Shuttle. Its second stage is a liquid

oxygen-liquid hydrogen engine similar to the upper stage engine o the Saturn V rocket,

which propelled the Apollo missions to the Moon. Ares I will weigh 2 million pounds

(907 metric tons) at lito, will stand about 325 eet tall (100 meters), more than a ootball

eld, and will deliver the Orion crew exploration vehicle to low Earth orbit (LEO).

Ares I will produce roughly 3.5 million pounds-orce (15.6 meganewtons) o thrust at

lito. The RSRB booster will burn or about 126 seconds. At the end o this burn, the

rocket will be about 36 miles (58 kilometers) above Earth, traveling at a speed o 4,445

miles per hour (2,000 m/sec). The vehicle will have lost 69% o its weight by having

burned up 1.4 million pounds (630 metric tons) o solid rocket uel. The RSRB, no

longer needed, will be jettisoned and will all back to Earth, where it will be recovered

to be used again. The liquid uel J-2X engine o the Ares I upper stage will burn or

about 464 seconds, producing 294,000 pounds (1.3 meganewtons) o thrust, to lit

the crew module to a higher orbit at 185 miles (298 kilometers) above the Earth. In this

orbit, the vehicle will be traveling at about 17,500 miles per hour (7,800 m/sec).

Ares V, shown in Figure 6.2, is NASAs heavy-lit cargo vehicle that will enable NASA

to send more crew and more cargo to the Moon than the Apollo-era Saturn V. Ares

V will weigh 7.4 million pounds (3,357 metric tons) at lito, will stand 360 eet (110

meters) tall, and can carry 287,000 pounds (130 metric tons) to LEO. The Saturn V

was 4 eet (1.2 meters) taller but weighed nearly 1 million pounds (453,600 kilograms)

less than Ares V and carried approximately 39,000 pounds (17,690 kilograms) less

to the Moon. Ares V has a payload shroud more than 32 eet (10 meters) in diameter

or carrying more massive payloads. It is this unmatched lit capability that will not

only support extended exploration o most o the lunar surace, but will also supportnumerous human and robotic missions o exploration beyond the Moon.

Ares V has two stages. The rst stage is powered by two solid rocket boosters similar

to the Ares I rst stage and a core stage powered by ve commercial RS-68 liquid uel

engines working together. Ater the boosters burn out, they all to Earth, and the core

stage continues operating to an altitude o roughly 87 miles (140 kilometers). The stage

alls to Earth, and the second stage, called the Earth departure stage (EDS), ignites

to place the lunar lander, Altair, in Earth orbit. The EDS is powered by the same J-2X

engine as the Ares I upper stage. Ater the astronauts in Orion rendezvous and dock

with Altair, the EDS ignites again to send the Orion, Altair, and the crew to the Moon.Figure 6.1.Ares I.

Figure 6.2.

Ares V.


13/78

NASA Engineering Design Challenge:Spacecraft Structures 2007 9

Spacecrat Structures

Every pound that is carried to space requires uel to do so, regardless o whetherthat pound is cargo, crew, uel, or part o the spacecrat itsel. The more thevehicle and uel weigh, the ewer passengers and smaller payload the vehiclecan carry. Designers try to keep all the parts o the vehicle, including the skel-eton (or structure), as light as possible. To design a lightweight structure is verydicult, because it must be strong enough to withstand the tremendous thrust(or orce) o the engines during lito. Throughout the history o space vehicles,engineers have used various strategies or the structure.

In order to make the Ares spacecrat as light as possible, NASA engineersare constructing them o lightweight, strong materials, such as Al-Li 2195, analuminum-lithium alloy, which is less dense and stier than pure aluminum.NASA engineers also design structures that use as little material as possible toachieve the strength and rigidity they need. So, or example, they make use o anetwork o hollow tubular struts (called a truss) rather than use more compact,but heavier solid beams.

This engineering design challenge ocuses on the Ares V thrust structure, whichattaches the ve liquid uel engines o the Ares V to the body o the spacecrat.The thrust structure is an essential part o the spacecrat, which must be keptlightweight. As they burn, the ve RS-68 engines o the Ares V produce about3,510,275 pounds (1,592 metric tons) o thrust. This means that the thrust struc-ture must bear a load equivalent to 3,510,275 pounds (1,592 metric tons) oweight pushing on it. The thrust structure must not only withstand this terricorce, it must transer it to the vehicle in a balanced way, without damaging thevehicle.

Students can calculate the pay-

load to total weight ratios or (a)

the amily car and (b) a student

riding a bicycle.

Students may be amiliar with

design strategies used to make

lightweight bicycles.

Figure 6.3. View o Ares V engines and thrust structure. This

image appears in a larger version in the "Masters" section.

Figure 6.4. Ares V engines attached to

thrust structure. This image appears in

a larger version in the Masters section.


14/78


Space ShuttleLength Orbiter: 122 feet

(37 meters),

Overall: 184 feet (56 meters).

Width Orbiter: 56.67 feet (17.3 meters),

Overall: 76.6 feet (23 meters)

Takeoff weight: 4.5 million pounds

(2,041 metric tons)

Fuel weight: 4.3 million pounds,

including Solid Rocket Boosters and

external fuel tank (1,937 metric tons)

Main propulsion: 3 Main Engines,

2 Solid Rocket Boosters

Take-off thrust: 3.3 million pounds or

(1,497 metric tons)

Maximum speed:

17,500 miles/hr (7,800 m/sec)

Largest payload it can carry into orbit:

50,000 pounds (22.7 metric tons)

Ares I

Length: 325 feet (100 meters)

Width: 18 feet (5.5 meters)

Takeoff weight: 2 million pounds

(907 metric tons)

Propellant fuel weight: 1.7 million

pounds (764 metric tons)

Main propulsion: single RSRB

Take-off thrust: 3.5 million pounds-

force (15.6 meganewtons)

Maximum speed: 17,500 miles/hr

(7,800 m/sec)

Maximum speeds at end of staging:

Ares I First Stage: 6250 f t/sec

(1,904 m/sec)

Ares I Upper Stage Orbit Injection:

25,582 ft/sec (7,798 m/sec)

Largest payload it can carry into or-

bit: 56,512 pounds (25.6 metric tons)

Ares V

Length: 360 feet (110 meters)

Core stage diameter: 33 feet (10 me-

ters)

Takeoff weight: 7.4 million pounds

(3,357 metric tons)

Core stage fuel weight: 3.16 million lbs

(1,435.5 metric tons)

Main propulsion: 2 RSRBs plus

5 RS-68 liquid fuel engines

Take-off thrust: 10.65 million pounds

(47.4 meganewtons)

Maximum speed: 24,462 mi/hr

(10,935 m/sec)*

Maximum speeds at end of staging:

Ares V SRB separation: 3,958 ft/sec

(1,206 m/sec)

Ares V Core stage cutoff: 16,227 ft/sec

(14,946 m/sec)

Ares V Earth Departure Stage (orbital

burn): 25,460 ft/sec (7,760 m/sec)

Largest payload it can carry into orbit:287,000 pounds (130 metric tons)

*Trans-Lunar Injection (TLI)

NOTE: The Ares vehicles are a very

preliminary confguration and will

be subject to change as the design

progresses.

Figure 6.5.

Ares I.Figure 6.6.

Ares V.

Figure 6.7. Space Shuttle.


15/78


Questions for class discussion or homework

1. Why is it important to make the launch vehicle as lightweight as possible?________________________________________________________________________

________________________________________________________________________

2. What are the Ares launch vehicles?

________________________________________________________________________

________________________________________________________________________

3. What are some ways NASA engineers could make the Ares launch vehicles aslightweight as possible?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

4. I it costs $10,000 to lit a pound (hal a kilogram) o payload into orbit aboardthe International Space Station, calculate the cost o sending yoursel intospace. How much would it cost to send yoursel, your amily and your petsinto space?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________


16/78


Answers to questions for class discussion or homework

1. To maximize the amount o payload it can carry to orbit.

2. The Ares I and V are the next generation o space launch vehicles.

3. By making the vehicles o a lightweight composite material and by using atruss structure to support the engines.

4. Answers will vary.


17/78


7. Teacher PreparationIn order to prepare yoursel and your classroom or this Engineering DesignChallenge, you should:

UsetheBackground Inormation section in this guide, and the Engineer-ing Design Challenge web site at http://edc.nasa.gov to amiliarize yourselboth with the spacecrat structures used by NASA and the science andengineering concepts you will be introducing.

Readthroughtheday-by-dayactivitiesinthefollowingsectionofthis

guide.

Gathertherequiredmaterials.

Buildthelauncher.

Buildthetestrockets.

Practicethetestprocedurewithyourowndesigns. Preparethematerialsfortheclassroom.

Setuptheclassroom.

Organizestudentsinteams.

Reviewsafetyprocedures.

NotifyparentsusingtheierincludedintheMasters section.

Required Materials

Required Materials Approximate costper unit

Minimum quantity

or a ew teams(60 structures)

Recommended quantity

or 1215 teams(120 structures)

Add or each

additional team(10 structures)

Crat Sticks 1/2 1500 3000 250

Dowels 15 to 50 or 3 t. 5 5 0

Hot-melt Glue(low-temperature type)

5 to 50 per stick 12 20 2

Corrugated Cardboard ree 60 120 10

35 mm Film Cans ree 10 20 1

1-liter Soda Bottles ree or 5 8 20 1

2-liter Soda Bottles ree or 5 3 5 0

Weight$2.35 or a 50-lb

(23-kg) bag o sand20 to 50 lbs total

Brass Launch Tubes 80 or 4 inches 4 8 1

Package Tape $2.00 1 roll 1 roll 0Small Paper Cups 4-oz, waxed 2 or 3 12 36 3
http://edc.nasa.gov/http://edc.nasa.gov/


18/78

14 NASA Engineering Design Challenge:Spacecraft Structures 2007

Notes on MaterialsCraft Sticks

Use a stick that is available in large quantity at a reasonable price in your area.Several kinds are suitable. Crat sticks the size o match sticks are excellent orthis project. They are just under 3/32 inch (2 mm square) and are sold in cratstores. They are 2 5/8 inches (6.7 centimeters) long and come in a package o500 or about $2.00. You might nd toothpicks that have a square cross sectionin the middle portion. They would be a little more dicult to work with, but alsovery good.

Basswood and balsa sticks are available in crat and art-supply stores ina variety o sizes but they are likely to be excessively expensive. 3/32- or1/8-inchsquarewouldbesuitableforbasswood;1/8or3/16-inchsquare

would be suitable or balsa. Round bamboo skewers or kitchen use couldbe used. They are about 3/32 inch (0.2 centimeter) in diameter and about 12

inches (30 centimeters) long. You may wish to cut o the sharp point beoredistributing them to students.

DowelsBasic dowels that you might nd at any hardware, lumber, or crat store areuseul or making strong structures that are heavier than necessary. 1/8-, 3/16-,and1/4-inchdiameterswouldbehandy.Anykindofwoodwilldo;birchis

common and inexpensive.

Corrugated CardboardThis will be cut into 3 1/2 inch (9-centimeter) squares. Scrap rom old boxes issuitable i it is fat and undamaged.

35 mm Film CansThese are the plastic containers in which the roll o lm comes. Usually photostores can give you a big bag o them.

WeightsStatic testing o structures requires weights that can be placed on the structure.One good approach is to ll some 1- or 2-liter bottles with sand. You will need toknow how much your weights weigh.

Brass Launch TubesSee the notes in the section, Build the Rockets, on Page 17.

Package TapeAny sturdy tape 2-3 inches wide will do. Transparent is best.

Tools: SafetyGlassesorGoggles.

GlueGun(low-temperaturetypeisrecommended).

CardboardCutter(utilityknifeorboxcutterforcutting31/2inch(9centi-meter) squares).

Strongscissors(forcuttingsticksortrimmingcardboard).

Rulers.

YardStick(ormeterstick).


19/78


Build the Launcher

Materials Needed

Ring Stand (Launch Rod)A ring stand o the type used in chemistry labs with a vertical rod 1/2 inch indiameter and approximately 3 eet (1 meter) tall. (This is taller than most.) Thekind with a large heavy base is best.

You can use any straight metal rod 1/2 inch in diameter and 3 to 4 eet (0.9 to 1.2meters) long i it can be attached to a suitable base. I you have a way to threadsuch a rod or several inches at one end, you can then attach it to a base withnuts and washers.

Weight for Dropping

A sturdy cloth bag about the size o a loa o bread containing about 15 to 20pounds (7 to 9 kilograms) o sand or ne gravel will work well. I you plan to docalculations using the mass o the dropped weight, 22 pounds (10 kilograms)provides a convenient gure. Lead shot makes an excellent ller or the dropweight. Sturdy sewing o the bag is important.

Wooden 2 by 31 piece 50 inches (1.3 meters) long (or the launch lever)

1 piece 4 inches (10 centimeters) long (or the mounting block)

You can use a 2 by 4 in place o the 2 by 3. This works just ne. The 2 by 4 isheavier than necessary.

Plywood Base Board3/4 or 1/2 inch thick, 10 by 14 inches (25.4 by 35.6 centimeters). Any size rom8 by 12 inches (20 by 30.5 centimeters) to 12 by 16 inches (30.5 by 40.6 centime-ters) is ne.

HingeA T style hinge is ideal. A good size has one fap 3 1/2 inches (9 centimeters)wide (in the direction o the pivot pin) and about 1 inch (2.54 centimeters) long.The other fap is triangular, about 1 1/2 inches (3.8 centimeters) wide at the pin,and about 4 inches (10 centimeters) long. This kind o hinge costs about $3.00.You may use almost any kind o sturdy hinge that can be attached to the launchlever and the mounting block.

Flat Head Wood ScrewsThese attach the hinge to both 2 by 3s and the 2 by 3 to the base board.

Anything that ts will work ne. The hinge needs screws that match the hingeand the mounting block should be mounted with screws long enough to gosolidly into the block. See Figure 7.1.

Figure 7.1. Example launch

testing station.


20/78


ConstructionIt will be easiest to assemble the launcher i you begin by locating the places

where screws will go and drill pilot holes or all o them beore you screwtogether any o the parts.

1. Place the hinge on the launch lever (2 by 3 wood length) so that the pivot pino the hinge is at the midpoint o the length o the launch lever. Mark the loca-tion or the screws. See Figure 7.2. (I you want to be able to move the hingeto a dierent location as explained in Alternate Hinge Location below, this isthe best time to mark the additional mounting holes.)

2. Put the mounting block next to the short fap o the hinge. Mount the hinge ata height so that the launch lever will be able to swing in both directions about2 to 3 inches (5 to 8 centimeters) rom horizontal. I you mount the hinge toolow,theleverwillbeabletoswinginonlyonedirection;itsmotionintheother

direction will be blocked by the mounting block. Mark the location or those

screws on the mounting block.3. Place the mounting block in the center o the base board and mark on the

bottom o the base board the location or the screws to attach the mountingblock to the baseboard.

4. Drill pilot holes through the base board into the mounting block.

5. Drill pilot holes or the hinge mounting screws in the mounting block andlaunch lever.

6. Drill clearance holes or the wood screws in the baseboard and countersinkthem. The heads o the screws need to sink into a prepared depression sothey are fush with or below the baseboard surace.

7. Screw the short fap o the hinge to the mounting block, screw the long fap

o the hinge to the launch lever, and screw the mounting block to the baseboard. See Figure 7.3. (This is the order o assembly that provides easiestaccess or the screwdriver.)

Optional Improvements

Alternate Hinge LocationYou might want to experiment with moving the hinge point to a position 20inches (0.5 meter) rom one end, so that the ratio o the lengths o the ends othe lever is 2 to 3.

One Piece Launch StandI you mount the launch rod and the launch lever on the same base board theywill stay correctly aligned.

Midpoint of Lever

Figure 7.2. Side view o base,

hinge, block, and lever.

Figure 7.3. End view o base,

block, hinge, and lever.


21/78


Build the Rockets

Materials Needed

Soda Bottles (and Caps)You will use the 1-liter size or most o the rockets, but it is good to have some2-liter bottles on hand as well. The bottles that have a 5-lobe base are better orthis activity than other kinds. See Figure 7.4.

Brass Launch TubesCrat, art supply, and hobby stores sell brass tubing in sizes that just t insideeach other, so it is sometimes called telescoping tubing. It comes in 12-inchlengths. 9/16 inch outside diameter is just right to t easily over the launch rod(the ring stand). You will need to cut the tube into 4-inch (10-centimeter) lengths,which you can do with a tubing cutter or a ne saw. You can also use PVC pipe

with a similar diameter.

Package TapeThis is used to attach the launch tube to the soda bottle. See Figure 7.5.

ConstructionFill the bottle with water and cap it tightly. Tape a 4-inch (10-centimeter) length otube to the fat cylindrical part o the bottle. Be sure the tube is vertical.

Practice Launching a RocketOnce you have constructed the launcher and rockets, you will want to try somemodels yoursel to become amiliar with adjusting the launcher and assuringconsistent test conditions.

You will need at least one other person, or two i you want to observe the launchprocedure rather than doing it yoursel. One person will drop the weight on theend o the lever. The other person will catch the bottle ater it reaches its peakand begins descending.

Slide the rocket tube onto the ring stand and centerthe bottle on the end o the launch lever. See Figure7.6. The end o the lever should be as close to thering stand as it can get without hitting it as it pivots.The catcher should stand behind or to the side o

the launch rod and signal when ready or the launch.At this signal, the dropper should count down anddrop the weight rom about knee-high squarely onthe other end o the lever. See Figure 7.7.

Figure 7.5. Brass tube attached

to bottle with package tape.

Figure 7.4. Bottle with a 5-lobe base.

Figure 7.6. Forces beore launch.


22/78


Notice that the lever and the launch rod may move slightly out o alignmentduring each launch. You will want to make sure that the lever is square with the

launch rod and that the bottle (and the thrust structure when there is one underthe bottle) is centered on the lever beore each launch.

Prepare the Materials or the ClassroomYou may wish to assemble the materials into kits beore distributing them tostudents. In this way you can reduce the amount o time spent on distributingmaterials. You can also ensure that all design teams receive the same materi-als. I you choose to incorporate the additional design constraint o a budget(described in the Extensions section on Page 44 o this guide), assembling kitsin advance will simpliy tracking the budget.

Set up the Classroom

Team Work AreaSet up the classroom or laboratory work to be done in teams. Each pair o

students should have a clear work area near an electrical outlet (or the glue gun)where they can organize their materials and build their designs. A classroomdesk or table will do.

LauncherSet up the launcher, in a central location away rom walls, where students cangather around.

Figure 7.7. Testing a thrust

structure.


23/78


Organize Students in TeamsI students work in pairs, they will all have the opportunity to engage in all

aspects o the activity: design, construction, testing, and recording. You maynd that larger teams make it dicult or all students to have a turn manipulatingthe materials.

Review Saety ProceduresIn the interest o ensuring the saety o the students and o yoursel, you shouldbe aware o several saety issues during this activity.

Hot glue guns or glue pots have hot metal suraces that can burn the skin whentouched. Show students which areas are hot and advise them to be careul.The hot glue itsel can be painul, but is unlikely to cause any serious burn.Nonetheless, students should be warned that the glue is hot.

When launching rockets, students should ollow a strict procedure o notiyingone another verbally when they are ready to launch and then counting down tothe launch. This will ensure that a rocket is not launched when the catcher isunprepared.

Require that the catcher wear eye protection.

Cutting a small slit in a tennis ball and then placing the ball onto the end othe launch rod will reduce the possibility o injury rom the rod. The tennis ballbumper has several drawbacks: 1. It acts as a brake on the rocket and makesor a less exciting launch, 2. I the tennis ball is too secure, the rocket maybounce o o it making it dicult to catch.

Teaching Strategies or an Engineering DesignChallengeLike any inquiry-based activity, this Engineering Design Challenge requires theteacher to allow students to explore and experiment, make discoveries, andmake mistakes. The ollowing guidelines are intended to help you make thisactivity as productive as possible.

Besuretodiscussthedesignsbeforeandaftertesting.Discussingthe

designs beore testing orces students to think about and communicatewhy they have designed as they have. Discussing the designs ater test-ing, while the test results are resh in their minds, helps them refect on andcommunicate what worked and what did not and how they can improve

their design the next time. Watchcarefullywhatstudentsdoandlistencarefullytowhattheysay.This

will help you understand their thinking and help you guide them to betterunderstanding.

Remindthemofwhattheyhavealreadydoneandcomparetheirdesigns

to previous ones they have tried. This will help them learn rom the design-test-redesign approach.


24/78


Steerstudentstowardamorescienticapproach.Iftheyhavechangedmultiple aspects o a design and observed changes in results, ask

students which o the things they changed caused the dierence inperormance. I they are not sure what caused the change, suggest theytry changing only one or two o the aspects. This helps them learn thevalue o controlling variables.

Beawareofdifferencesinapproachbetweenstudents.Forexample,some

students will want to work longer on a single design to get it just right.Make it clear that getting the structure designed, tested, and documentedon time is part o the challenge. I they do not test a lot o models, they willnot have a story to tell at the end. Remind them that engineers must comeup with solutions in a reasonable amount o time.

Modelbrainstorming,carefulobservation,anddetaileddescriptionusing

appropriate vocabulary.

Askopen-endedguidingorfocusingquestions.Forexample:Howdoes the orce get rom the launch lever to the rocket? or What madethis design stronger than another? Keep coming back to these questionsas the students try dierent designs. Encourage students to address thesequestions in their journals.

Requirestudentstousespeciclanguageandbepreciseaboutwhatthey

are describing. Encourage them to reer to a specic element o the design(column, strut, joint, brace, etc.) rather than it.

Comparedesignstothoseofothergroups.Endorseborrowing.After

all, engineers borrow a good idea whenever they can. However, be surethat the team that came up with the good ideas is given credit in docu-mentation and in the pre-test presentation. Borrowing should also bedocumented in student journals.

Emphasizeimprovementovercompetition.Thegoalofthechallengeis

or each team to improve its own design. However, there should be somerecognition or designs that perorm extremely well. There should alsobe recognition or teams whose designs improve the most, or teamsthat originate design innovations that are used by others, or elegance odesign, and or quality construction.

Classifydesignsandencouragethestudentstocomeupwiththeirown

names or the designs to be used in the class.

Encourageconjecturing.Getstudentstoarticulatewhattheyaredoingin

the orm o, I want to see what will happen i

Connectwhatstudentsaredoingtowhatengineersdo.Itwillhelp

students see the signicance o the design challenge i they can see thatthe process they are ollowing is the same process that adult engineersollow.


25/78


Helping Students Understand the

Design ProcessEngineering involves systematically working to solve problems. To do this, engi-neers employ an iterative process o design-test-redesign, until they reach asatisactory solution. See Figure 7.8.

In the Engineering Design Challenges, students experience this process. To helpstudents visualize the cyclic nature o the design process, we have provided areproducible chart that you can use in a class discussion.

Once students have sucient experience in designing, building, and testingmodels, it is valuable or them to ormally describe the design process they areundertaking. Students require a signicant amount o reinorcement to learn thatthey should study not just their own results, but the results o other teams as

well. They need to realize that they can learn rom the successes and ailures oothers, too.

Select a time when you eel the students have had enough experience with thedesign process to be able to discuss it. Use the black-line master o The DesignProcess to make an overhead transparency. Project it on a screen. Then, usingit as a guide, go through the process step-by-step, using a sample design as anillustration. It is useul to hold up the model and point out specic eatures thatmay be the result o studying the test data, unsuccessul builds, or additionalresearch. For example, using a particular model, ask How did this eature comeabout? Where did you get the idea? Was it the result o a previous test, done byeither you or by another team?

Figure 7.8. A larger version o this image is included in the Masters section at the end

o this guide.

The Design Process

Analyze

Results

Record DataTest

Build

Design


26/78


Session 1

Introducing the Challenge and Getting StartedIn this rst session, you will introduce the activity and provide students withbackground inormation about NASA, the Ares launch vehicles, and spacecratstructures. You will dene the challenge and discuss how engineers approacha design problem. Students will practice dropping the sandbag until they canconsistently launch the bottle rocket to orbit. You will conclude the session bylaunching a teacher-built model thrust structure and challenging students tobuild models that are lighter-weight.

Learning Goals Understandanddenethruststructure.

Recognizetheneedformodels.

Understandtherelationshipbetweenamodelandtheactualobjectbeing designed.

Recognizeaneedforastandardtestprocedure.

Makeobservationsandcollectdata.

Understandtheneedforaveraging.

Calculateaverages.

Materials Transparencies or overhead projector. (Masters can be ound at the end o

this guide.)

Ares Launch Vehicles.

Thrust Structures.

The Challenge.

Launchstand(includeslaunchlever,ringstand,weighttodrop,bottle

rocket and yard stick or ring stand with le card to set drop height).

Atoo-heavyoverbuiltthruststructurebuiltbytheteacher.(Seesection6 later in this session or a model.)

Yardstick(ormeterstick). Filecardorsimilarsizepieceofamanilafolder.

Wallchart(orchalkboard)forrecordingdropheightsandlaunchresults.

Optional: Additionalringstand.

Thirdringstand.

String.

8. Classroom Sessions


27/78


1. Introduce the UnitElicit students knowledge o the Space Shuttle, the International Space Station,

the Apollo missions to the Moon, and spacecrat in general. Use the backgroundinormation in the previous section, and pictures, video, or models o the Ares

vehicles to introduce the concept o a reusable launch vehicle. Introduce the

Ares launch vehicles, which are being designed to replace the Space Shuttle.

Ask about what needs to be considered in designing a vehicle that must get

into space and return to Earth. Discuss the signifcance o mass (optional:

discuss the dierence between weight and mass). Explain to students that they

will take on the role o engineers or this unit. They will attempt to solve a prob-

lem that NASA engineers are working on designing: A lightweight, but strong

thrust structure or the vehicle.

2. Introduce the Challenge

Bring out the launch stand and choose a student to be the catcher. Launch arocket; but, drop the weight so that the rocket barely moves. Ask students to

identiy which parts o the rocket each part o the model represents. (The lever

is the engine providing the thrust, the sandbag weight represents the energy

o the engines, and the bottle is the body o the spacecrat including the liquid

uel tanks.)

Explain to students that the thrust structure is the part o the spacecrats skele-

ton that holds the engine on to the rest o the vehicle. Use the Thrust Structure

masters to compare the Ares rocket thrust structure to the bottle rocket thrust

structure. Explain that, unlike the demonstration in which the bottle rocket gets

one big push rom the lever engine and then separates rom it, a launch vehicle

must be pushed constantly by the engine until it reaches orbit. The Ares I and V

must carry their engines with them. The push o the engine must travel throughthe thrust structure to the rest o the rocket.

Defne the challenge. Either use a transparency made rom the Design Chal-

lenges master at the end o this guide, post a copy prominently in the room,

or hand out copies to each team o students.

Figure 8.1. Ares I and Ares V.


28/78


The challenge:

Build the lightest weight thrust structure that will withstand the orce o launch to orbit at least three times.Launch to orbit = propelling a 1-liter bottle o water to the height o approximately 3 eet (1 meter) into the air.

Design constraints:Use only the specied materials.

The thrust structure must be taller than 2 inches (5 centimeters) and must allow space in the center or uellines and valves represented by a 35mm-lm canister without its lid.

Explain to students that during the ollowing three class sessions, they will

design a thrust structure, launch it, record the results, and then try to improve onthe design by making it lighter and stronger. They will get at least our chances toimprove on the design. Show students your heavy design, and tell them that youare sure they can do better!

3. Explain the Culminating ActivityExplain that each team will spend one class period at the end o the challengeconstructing a storyboard or poster that will tell the story o the develop-ment o their thrust structure. Using the storyboard, each team will then make apresentation to the class explaining the evolution o their design.

The storyboard should contain at least three o the teams recording sheets. Ipossible, students should attach three o the actual tested models. The poster

should show the evolution o the teams design rom its initial to intermediate andnal design stages. Essentially, it should tell the story o the design processand explain how and why the design changed. It should conclude with a concisestatement o what we learned.

In addition to completing the recording sheets, direct students to keep runningnotes, diagrams, questions, research ndings, data, etc., in a journal or log. These

journals will provide an excellent resource or documenting their experience whenthey need to make their storyboard.

4. Determine the Engine ThrustExplain to students that their rst task will be to determine the necessary thrust

to propel the bottle rocket to orbit. They will determine a drop height or thesandbag so that the rocket just fies o the ring stand. Discuss with studentswhy you do not want it to fy too ar o the launch rod. (That would be subjectingthe structure to more orce than necessary and overshooting orbit.)

Choose a volunteer to drop the sandbag and another to catch the rocket.(Launch this rocket without a thrust structure.) Measure the height o the dropwith a yard stick or measuring tape or punch a small hole in a le card or pieceo manila older and slide it on a ring stand to mark the height. Have the studentsstart by dropping the weight rom a very low height and gradually increase thedrop height until the bottle just barely fies o the ring stand. You might have adierent pair o students perorm the launch with each increase in drop height.


29/78


Continue to launch the rocket until students can consistently launch the bottlethree times to the desired height. You might want several pairs o students to

conrm the height.When you have determined the optimal drop height, record it and post it in thesame place as the challenge. Mark a ring stand at that height with tape or tapethe le card onto the ring stand. Optional: Use two ring stands and tie a stringbetween them at the drop height.

Optional: Use Different Drop Mass and Drop HeightI you are able to conveniently change the mass being dropped, you couldchoose a drop height and then nd the required mass or launching the bottleto orbit using that weight. Students could record the results o using dierentamounts o sand in a table such as this:

Trial # Launch Masspounds (kg) Drop Masspounds (kg) Drop Heightinches (cm) Altitudeinches (cm) Orbit?(Y/N)

1

2

3

5. Discuss the Results

Ask students: How much mass are we launching to orbit? (2.2 pounds or a 1kilogram bag o sand.) Whats the source o the propulsive orce? (22 pounds ora 10 kilogram bag o sand.) What orces are acting on the bag o sand when it issuspended in the air beore the drop? (Gravity and the students muscles.) Whatorces are acting on the bag when it is released? (Gravity.) Trace where the orce

goes. (Down on one side, up rom the other end o the lever.) Optional: Discusswhy it is important or the lever to be sti rather than fexible.

It is instructive or students to think about how the model bottle rocket and anactual rocket, such as the Ares V, are the same and dierent. Here are typicalanswers.

Bottle Rocket Ares V

Source o the thrust The lever2 solid rocket boosters

plus 5 liquid uel engines

Source o engine energy Gravity on sandbag Combustion o uel creates it

Thrust duration Fraction o a second Minutes

Thrust magnitude Small10.65 million pounds

(47.4 meganewtons)

Mass o rocket 2.2 pounds (1 kilogram)7,400,000 pounds

(3,356 metric tons)

Thrust depends on

Mass o sandbag

Drop height

Strength o gravity

Energy density o uel

Mass o uel burned/sec

Engine design

Homework/Assessment. Sketch

the test stand and identiy the

relevant parts. I you wanted to

propel your 1-liter bottle rocket to

a height o 1 yard, how much mass

should you drop on the end o the

lever and rom what height?

Use the master, Comparing the

Bottle Rocket and the Ares V, as

an overhead and discuss how the

model compares with the real

thing.

I you graph the data in this table

you may see some interesting

relationships.


30/78


Figure 8.2. A heavy design.

6. Demonstrate a Poorly Designed Baseline Model(Note: I time does not allow or this demonstration in this session, it can be let

until Session 2, Step 6.) In order to provide a baseline model or a thrust struc-ture, you should build one that is truly a juggernaut. See Figure 8.2. For example,use 3-inch (7.6-centimeter) lengths o 1/4-inch dowels clustered in threes andattached to cardboard plates on top and bottom using a generous amount oglue. This structure will have a mass little more than 4 ounces (113 grams) butwill certainly withstand numerous launches. Students will quickly see ways toimprove upon this crude design and will take pleasure in building a model that isbetter than the teachers.

7. Wrap-upShow students the crat sticks and the square o cardboard they will use or theirrst design. Ask them to think about thrust structure designs beore the next

session.


31/78


Session 2

Design 1In this session, students design and build their rst thrust structure using theprovided materials. It is important during this session to establish consistentprocedures or testing including:

Pre-testapprovalofdesignandrecordingsheet.

Oralpresentationofkeydesignfeaturesbystudentsbeforelaunch.

AccuratetestingandreportingofresultsonTestResultsSheet.

Post-testdiscussionofthedesignandthetestresults.

Learning Goals Practiceconstructiontechniquesincludinguseofgluepotorgluegun.

Recognizetheneedforcleardocumentation.

Practicedocumentingdesign.

Practicemakingandrecordingobservations.

Beginthinkingabouthowtomakedesignsstrongandlightweight.

Materials Launchstand,sandbag,ringstand.

Craftsticks.

Gluegunsandgluesticks.

31/2by31/2inchsquare(9by9centimeter)piecesofcardboard. Papercups(optional).

Transparencyandhandoutsofrecordingsheets.

Chartpaper(orchalkboard)forrecordinglaunchresults.

Abalanceorscaleaccuratetoatenthofagram.

Overheadprojector(optional).

1. Review the Design Challenge and the Design ConstraintsMake sure students understand the challenge. Use the master to review it.

2. Introduce the MaterialsExplain to students that they must build a thrust structure using the crat sticksand hot melt glue. The structure should be attached at the top to a square ocardboard on which the bottle will sit. The structure is NOT attached to card-board at the bottom.

3. Review Saety IssuesPoint out to students that the tip o the glue gun and the metal strip at the ronto the glue pot are hot and should be avoided. Review the procedure or burns.Remind students to wear saety goggles when launching their model.


32/78


4. Introduce the Recording SheetsIntroduce the Design Specications and Test Results sheets at the back o

the book. One way is to make a transparency o each sheet and project it onthe overhead. Tell students that these are where they will record all the details otheir designs and the results o their testing. Explain that engineers need to keepcareul records. Ask students why record keeping is so important. Discuss eachpart o the Design Specications and the Test Results sheets. Make surestudents understand that one sheet shows their model beore testing and thatthe other shows it ater testing.

Remind students to keep track o their designs by numbering their recordingsheets. Remind them that they will use their recording sheets to construct astoryboard at the end o the challenge.

Explain to students the importance o a detailed sketch o their design. Theirgoal in sketching should be that someone looking only at the sketch couldreconstruct their design. You may wish to show a completed recording sheetas a sample.

Two sketching techniques to introduce are detail views and section or cut-through views. A detail view is a separate close-up drawing o a particularportion o the design that may be dicult to show clearly in the drawing o theull design. A section view shows what the design would look like i it were slicedin hal. It enables the artist to show hidden parts o the design.

In addition to answering the questions on the design spec sheets, studentsshould also keep running notes, diagrams, questions, research ndings, data,etc., in a journal or log. These journals could be as simple as notes taken on theback o the design spec sheet. A journal will provide an excellent resource or

documenting the experience when a student needs to make the storyboard.

5. Explain the Test Procedure Whentheirdesigniscompleted,theteamcompletesarecordingsheet

and brings the model and the recording sheet to the teacher.

Theteachercheckstherecordingsheetforcompletenessandaccuracy.

Theteacherchecksthatthemodelhasconformedtoalldesignconstraints.

Beforetheirmodelistested,eachteammustdoabrieforalpresentation

(or the entire class) in which they describe the key eatures o the design.

Duringthetesting,theteamshouldcarefullyobserveandrecordthe

perormance o their design.

6. Students Design and Build their ModelsI you did not have time to complete the demonstration o a poorly designedmodel, do it now. See Steps 6 and 7 in Session 1.

Allow 1015 minutes or this rst design and build. Establish a cut-o time whenyou will begin testing. Teams that do not have designs ready to test by the cut-o time must wait until the next round o testing.

As an extension activity, have

students try to reconstruct

another teams design using only

the recording sheet. Assess the

recording group on the quality o

the sketch and the constructing

group on their ability to interpret

the sketch.


33/78


7. Approving Models or TestingWhen a team delivers their design and recording sheet or testing, check the

ollowing:

Model uses only allowable materials.

Model is at least 2 inches (5 centimeters) tall.

A 35mm lm canister (without lid) ts entirely inside the thrust structure.

The model has a team name or identiying mark on it.

The recording sheet is completely flled out, including a satisactory

sketch.

I the model is approved, place it on the testing station table. You might call thisbeing on deck.

8. Test the ModelsBegin testing when most o the teams designs have been approved. Havestudents stop working and gather around the launch station.

Older students may be able to continue working while other teams have theirmodels tested. For this arrangement to work, you will need to locate the launchstation in a central location where students can view it rom their work areas.

Beore launching, have a member o each team stand and hold up the model orshow it around to all other students. The representative should explain:

Keyfeaturesofthedesign.

Whythosefeatureswereused.

Wheretheideacamefrom(apreviousdesign,anotherteamsdesign,

another type o structure, etc.).

Assign a student to record the results o each test either on a chart on thechalkboard or on a large sheet o paper. The chart should include the ollowingcolumns, which are shown in Figure 8.3.

Team Design #Launch to Orbit (Y/N)?1 2 3

Figure 8.3. Chart test results.

I you choose to classiy the designs, you may also want to include a column ordesign strategy.

With no repairs allowed between launches, test each teams model three timesin succession. I you have more time, you may wish to increase the number olaunches per model. Inspect the model ater each launch. Students should makenotes about which structural members ailed or are in danger o ailing.

A ailed launch occurs when the rocket does not make it into orbit. A ailedlaunch also occurs when the design no longer meets the design constraints,that is, it is less than 2 inches (5 centimeters) high or a lm canister no longer tsinside. (Important: Do not leave the lm canister in the model when launching.)

As an option, you may wish to clas-

siy the models once each team

has presented. Students may come

up with classifcations based on

design strategies.

Figure 8.3 shows a model o a table

you may draw on the chalkboard

to record the perormance o each

thrust structure during a series o

three launches. The recommended

column headings include Team

name and Design number. There

are also three columns or record-

ing whether or not the rocket was

launched successully. A success-

ul launch includes one in which the

thrust structure was not damaged.


34/78


9. Discuss the Results o TestingThe post test discussion is critical to expanding students learning beyond the

design and construction techniques and connecting their design work with thescience concepts underlying their work.

Encourage students to hold the model and use it to illustrate their point whenthey talk about a particular design eature.

For each model, you should pose the same guiding question:

How did this structure transmit the orce o launch rom the lever tothe bottle?

Other discussion questions might include:

Whathappenedtoeachpartofthethruststructureduringthetesting?

Didanypartsofthedesignseemtofailbeforetherest?Why?

Whichdesignfeaturesweremosteffective?Whatmadethedesigns eective?

Have students trace the path o the orce through the structural members. Seeurther discussion o how to do this in the section, Linking Design Strategiesand Observations to Science Concepts, on Page 37.

Record (or have a student record) the most successul design eatures ona transparency or on a wall chart. This list should be expanded and revisedthroughout the activity as the students collectively discover which designs arestrong and lightweight.

I any o the columns in the structure have buckled, help students think abouthow to strengthen the posts, or example, through bracing. Here is an interesting

demonstration o buckling: Take a fexible ruler or yard stick. Stand it up on thefoor or table. Press straight down on the top end until the ruler begins to bowout or buckle. See Figure 8.4.

Try the same experiment with rulers o dierent lengths, but o the same thick-ness. Show that any post or column buckles i placed under a sucient load.Notice, however, that the shorter rulers can support more load without buckling.Then ask a student to grasp and hold steady the middle o the ruler. Repeat thepressure on top with your hand. Show that because the ruler is braced in themiddle, it is eectively two short columns rather than one long one.

You could also demonstrate the relationship between buckling and the lengtho a column by using a toilet paper tube and a paper towel tube. Load both withbooks. The longer one will buckle rst. (Make sure they are the same diameter

and made o the same thickness o cardboard.)

Now is a good time to review

the section Linking design strate-

gies and observations to science

concepts.

I one side o the structure has col-

lapsed, help students think about

the importance o balanced loads.

Figure 8.4. Bracing a ruler to pre-

vent buckling.


35/78


Sessions 3 and 4

Designs 2, 3, 4 and 5Using what they have learned rom the rst design, students revise and redesigntheir thrust structure in several more design-build-test cycles.

Learning Goals Distinguishbetweeneffectiveandineffectivedesignfeatures.

Incorporatedesignstrategiesgleanedfromexperimentationandobservation.

Reneobservationskills.

Drawconclusionsbasedonanalysisoftestresultdata.

Recordtestdata.

Analyzetestdataanddrawconclusions.

Reneunderstandingofstructuresandforces.

Materials Launchstand.

Craftsticks.

Gluegunsandglue.

2-literbottles,lledwithwaterorsand,withguidetubesattached.

31/2by31/2inch(9by9centimeter)squaresofcardboard.

Ringstandstobeusedforstatictesting.

1. Review the Previous SessionI a day or longer has passed since the previous session, review the results o therst round o testing. Review the successul and unsuccessul design eatures.

2. Design, Build, Test, and Discuss ResultsContinue to add successul design eatures to the list you started, on a transpar-ency or chart paper, in the previous session. Continue to ask students how thethrust is transerred rom the lever to the bottle and to have students trace theload paths on paper or directly on the model. Reer to the science concept linksollowing the session descriptions or connections that can be made betweenstudent observations and science concepts.

In the post-test discussion, lead students to make conclusions about the prob-able success o a thrust structure built o a certain number o crat sticks.

Allow students approximately 15 minutes to design, build, and complete arecording sheet or each model.


36/78


3. Introduce Static TestingUp to this point, the students have been testing their designs by launching them.

This kind o testing may destroy the models i they are not strong enough. Themodels that are plenty strong enough will not be destroyed, but models thatare just a little bit too weak may be damaged in testing. This is unortunatebecause the student may have to start over rom scratch, whereas i the modelwere still intact, it might be possible to make some minor change that wouldmake the model strong enough to survive three launches. As the students getcloser and closer to their optimum designs (as lightweight as possible, but stillstrong enough), they should become more attuned to the need or non-destruc-tive testing beore actual launch. You might reer to this as pre-testing or statictesting.

Introduce this section by asking the class whether they think it would be desir-able to have a way o testing the models that would not destroy those that were

just a little bit too weak. Point out, i you wish, that engineers preer non-destruc-tive proo testing o their designs whenever possible. Ask students to think onon-destructive ways they could test their models that would give them inorma-tion about the models strength, but would not suddenly destroy the model assometimes happens during a launch.

They will probably come up with ideas o squeezing the model, compressing it,or somehow gradually applying a load to it. The problem, o course, is that theydo not know how much to squeeze or how much weight to load onto the modelbecause they do not know how much compressive orce the model experiencesat launch. There are several ways you might determine the compressive orce atlaunch. Here are two approaches:

(1) Build a thrust structure model that will deorm, launch it, look at the deor-

mation, and then load up an identical model with enough weight to achieve thesame deormation. For example, glue a paper cup onto the cardboard square.See Figure 8.5. Launch a bottle to orbit using this thrust structure. Note theamount o deormation (crushing) o the cup. Take a second paper cup thruststructure and load it up with enough weight to achieve the same deormation.Note the amount o weight. This is the static weight any thrust structure mustwithstand at launch. I a student model withstands this amount o weight (andmaybe a bit more), then it should be able to survive launching.

(2) A second way to gure out how much weight a model needs to be able tosupport is to build a test model that is exactly strong enough or launch andthen to see how much weight it can support. For example, using paper cupsor the thrust structure, see i a single cup can withstand the orce o launch to

orbit three times. I it cannot, then add a second cup, nested onto the rst. Seei two cups can withstand launch orce. I not, then add another cup. When younally have enough cups to withstand three launches, you have an adequatethrust structure. Then see how much weight this model can support. Any modelthat can support the same weight or more should be able to survive the orceo launch. You can use a table like the one that ollows to record the results ogradually strengthening the paper cup thrust structure. See Figure 8.6.

Figure 8.5. A paper cup used

as a thrust structure.


37/78


Number o launches to orbit Weight required to crush in static test

Structure 1 (1 paper cup)

Structure 2 (2 paper cups)(etc.)

Figure 8.6. Static testing results chart.

The static weight that causes the structure to ail is the weight to use in uturestatic tests. I a design can support that weight, it should be able to withstandthree launches to orbit.

Ask students what they would look or in a static test. Here are some possibleideas:

Structuralmembersbuckling.

Gluejointslooseorunstable.

Entirestructureunsteadywhenmovedslightlysidetoside.Remind students that they should record the results o static testing directly ontheir Test Results sheet or in their journal or use in creating their storyboard.

You can lead rom this introduction o static testing into a discussion o the simi-larities and dierences between static and dynamic loads. Reer to the Linkingto Science Concepts section on Page 37 or a more detailed description o theconcepts involved.

Loading static weight onto a thrust structure will be easy i you use the bottlerockets themselves as the weights and use the ring stand to steady them. Placethe thrust structure on the base o the ring stand, slide the bottles brass sleeveonto the ring stand, and lower it gently onto the structure. Add more bottles asneeded. They should stack up nicely, held in place in a vertical stack by the ring

stand. I you need more weight than you can obtain using bottles o water, llsome bottles with sand. You can use bottles o dierent sizes, lled to dierentlevels with sand, in order to create a set o weights. O course, you will need todetermine the weight o your weights, and this, in itsel, is an interesting exer-cise or the students to carry out. To make static testing easy and accessibleto the class, set up a static test stand permanently in the room. Then you willhave a static test stand and a dynamic test stand.


38/78


Session 5

Construct a Storyboard/PosterAs a culminating activity, each team creates a storyboard poster that docu-ments the evolution o their thrust structure designs rom initial to intermediateto nal stage. The storyboard provides students with a way o summarizing andmaking sense o the design process. It provides opportunities or refection andenables students to see how their design work has progressed rom simple tomore sophisticated and eective designs.

Learning Goals Summarizeandreectonresults.

Organizeandcommunicateresultstoanaudience.

Materials Posterboardorlargesheetsofpaperapproximately2by3 eet (61.0 by

91.4 centimeters), one per team.

Markers,crayons.

Plasticsandwichbagsforholdingtestedmodels.

Glueortapeforattachingrecordingsheetsandtestedmodelstostoryboard.

1. Explain the Assignment

Explain to students that they will create a poster or storyboard that will tellthe story o their thrust structure design. Explain that proessional conerencesusually include poster sessions at which researchers present the results otheir work.

The storyboard should include recording sheets, tested models, and any otherartiacts they think are necessary. The storyboard should include a brie text thatdescribes how their design evolved through at least three stages: beginning,intermediate, and nal. I students have kept journals during the design process,they should use some o the notes rom their journals on the poster.

Students may attach their completed recording sheets or re-copy the inorma-tion onto the storyboard. I possible they should attach the actual tested models.Placing the model in a plastic bag and attaching the bag to the poster works well.


39/78


2. Defne the Assessment CriteriaExplain to students that their storyboards will be evaluated on the ollowing

criteria:

Aclearstoryline,organizedtoshowthedevelopmentofthedesign.

Showsatleastthreedesigns.

Containsclearsketcheswithkeyfeaturesidentied.

Includestestresultsanddescriptionofwhathappenedtothedesignduring the tests.

Includesconclusionaboutthemosteffectivethruststructuredesignand

why it is eective.

Usesscienticvocabulary.

Hasanappealinglayoutwithatitle.

Usescorrectgrammarandspelling.You may optionally assign additional research or invite students to do researchon their own initiative. Research ndings could also be included on the story-board. See the Resources section, on Page 46, or suggested starting points.Students could investigate:

Internalstructureusedinrockets.

Internalstructureusedinotherdevicesandvehicles.

Loadbearingpropertiesofmaterials.

3. Create the StoryboardsGive students an entire class session to create their storyboards. You might take

this opportunity to encourage students to practice sketching detail and sectionviews o the models as described in Session 2.

You might also want to assign several students to prepare a results posteror the entire class. This poster would make use o the charts on which yourecorded data rom each test session. The overall improvement o the classcould be calculated and displayed.


40/78


Session 6

Student PresentationsWhen all storyboards have been completed, put them on display in theclassroom. Allow students time to browse among the posters. Encourageconversation. Then reconvene the class and allow each team a ew minutes topresent their storyboard.

Another option is to conduct a poster session as might occur at a proessionalconerence. Hal the teams would remain with their posters to answer questionswhile the other teams browse. Ater about 15 minutes, the browsing teams standby their posters while the other teams browse. Browsing teams should ask ques-tions and engage the presenting teams in conversation.

The poster session provides an opportunity to invite parents, other teachers, andstudents rom other classes in to view student work.

Learning Goals Communicateresultstoanaudience.


41/78


Linking Design Strategies and Observations

to Science ConceptsAn important opportunity or science learning through this Engineering DesignChallenge comes rom the connections that students make between their designsolutions, their observations, and the underlying scientic principles. As youobserve students designing, as you conduct the testing, and as you discuss thetest results, there will be numerous opportunities to draw connections betweenwhat the students are doing and the scientic principles o motions and orces.This section provides suggestions and background inormation to help you drawthose connections at the moment they arise, the teachable moment, whenstudents are highly engaged and receptive to new inormation. This section isorganized according to observations the students might make and design strate-gies they might employ.

Observation: Tracing the Path o the ForceStudents should be able to trace the path o the orce rom the lever throughtheir structure to the bottle. They can do this simply by pointing out the path theorce will take or by drawing a sketch with arrows showing the direction o theorce. They can also color the structural members in the model. This will providean opportunity to discuss the advantages o distributing orce over a wide area.

Design Strategy: Balanced LoadsStudents should recognize that evenly distributed support will evenly dividethe orce o launch. You might point out that the bottom o the bottle is axially

symmetric and that there must be a reason or that design. See Figure 8.7. Askstudents to think about why many structures in the natural world, as well as thebuilt world are symmetrical. Perhaps it has to do with balanced loads.

Observation: Compressive ForcesAs students think about the orces on their model, they will realize that the mainorce on it during launch is compression, the direct result o the bottle press-ing down and the lever pressing up on the thrust structure. Thinking aboutthese compressive orces oers an opportunity or learning more about what isactually going on beore, during, and ater launch. Beore launch, as the thruststructure and rocket rest on the launch lever, the orces are balanced and,thereore, there is no acceleration. During launch, there clearly is acceleration,

and, thereore, there must be unbalanced orces on the thrust structure and therocket because they accelerate. Ater launch, there is, again, acceleration (ordeceleration, depending on the rame o reerence) as the rocket gradually slowsdown and stops at its apogee. So, there must be unbalanced orces causingthis acceleration. Acceleration would continue (downwards) i the catcher did notcatch the rocket and prevent it rom alling.

I students

221640main EDC Spacecraft Structures

Documents

Transcript of 221640main EDC Spacecraft Structures