Spacecraft Structures pdf - ER - NASA

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24 – NASA Engineering Design Challenge: Spacecraft Structures 2007The challenge:Build the lightest weight thrust structure that will withstand the force of launch to orbit at least three times.Launch to orbit = propelling a 1-liter bottle of water to the height of approximately 3 feet (1 meter) into the air.Design constraints:Use only the specified materials.The thrust structure must be taller than 2 inches (5 centimeters) and must allow space in the center for fuellines and valves represented by a 35mm-film canister without its lid.Explain to students that during the following three class sessions, they willdesign 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 four chances toimprove on the design. Show students your heavy design, and tell them that youare sure they can do better!3. Explain the “Culminating Activity”Explain that each team will spend one class period at the end of the challengeconstructing a “storyboard” or poster that will tell the story of the developmentof their thrust structure. Using the storyboard, each team will then make apresentation to the class explaining the evolution of their design.The storyboard should contain at least three of the team’s recording sheets. Ifpossible, students should attach three of the actual tested models. The postershould show the evolution of the team’s design from its initial to intermediate andfinal design stages. Essentially, it should “tell the story” of the design processand explain how and why the design changed. It should conclude with a concisestatement of “what we learned.”In addition to completing the recording sheets, direct students to keep runningnotes, diagrams, questions, research findings, data, etc., in a journal or log. Thesejournals will provide an excellent resource for documenting their experience whenthey need to make their storyboard.4. Determine the “Engine Thrust”Explain to students that their first task will be to determine the necessary thrustto propel the bottle rocket “to orbit.” They will determine a drop height for thesandbag so that the rocket just flies off the ring stand. Discuss with studentswhy you do not want it to fly too far off the launch rod. (That would be subjectingthe structure to more force 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 of the dropwith a yard stick or measuring tape or punch a small hole in a file card or pieceof manila folder and slide it on a ring stand to mark the height. Have the studentsstart by dropping the weight from a very low height and gradually increase thedrop height until the bottle just barely flies off the ring stand. You might have adifferent pair of students perform the launch with each increase in drop height.
NASA Engineering Design Challenge: Spacecraft Structures 2007 – 25Continue to launch the rocket until students can consistently launch the bottlethree times to the desired height. You might want several pairs of students toconfirm 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 file 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 HeightIf you are able to conveniently change the mass being dropped, you couldchoose a drop height and then find the required mass for launching the bottleto orbit using that weight. Students could record the results of using differentamounts of sand in a table such as this:Trial #123Launch Masspounds (kg)5. Discuss the ResultsDrop Masspounds (kg)Drop Heightinches (cm)Altitudeinches (cm)Orbit?(Y/N)Ask students: How much mass are we launching to orbit? (2.2 pounds or a 1kilogram bag of sand.) What’s the source of the propulsive force? (22 pounds ora 10 kilogram bag of sand.) What forces are acting on the bag of sand when it issuspended in the air before the drop? (Gravity and the student’s muscles.) Whatforces are acting on the bag when it is released? (Gravity.) Trace where the forcegoes. (Down on one side, up from the other end of the lever.) Optional: Discusswhy it is important for the lever to be stiff rather than flexible.It is instructive for students to think about how the model bottle rocket and anactual rocket, such as the Ares V, are the same and different. Here are typical“answers.”Bottle RocketAres VSource of the thrust The lever2 solid rocket boostersplus 5 liquid fuel enginesSource of engine energy Gravity on sandbag Combustion of fuel creates itThrust duration Fraction of a second MinutesThrust magnitude Small10.65 million pounds(47.4 meganewtons)Mass of rocket2.2 pounds (1 kilogram)7,400,000 pounds(3,356 metric tons)Thrust depends onMass of sandbagDrop heightStrength of gravityEnergy density of fuelMass of fuel burned/secEngine designIf you graph the data in this tableyou may see some interestingrelationships.Homework/Assessment. Sketchthe test stand and identify therelevant parts. If you wanted topropel your 1-liter bottle rocket toa height of 1 yard, how much massshould you drop on the end of thelever and from what height?Use the master, “Comparing theBottle Rocket and the Ares V,” asan overhead and discuss how the“model” compares with the “realthing.”
Page 2 and 3: Cover Illustration:NASA Ares I and
Page 4 and 5: ii - NASA Engineering Design Challe
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Page 19 and 20: NASA Engineering Design Challenge:
Page 21 and 22: NASA Engineering Design Challenge:
Page 54 and 55: NASA Engineering Design ChallengesD
Page 56 and 57: Resources for Further ExplorationEn
Page 58 and 59: Ares I
Page 60 and 61: Artist’s Rendering of the Ares Vo
Page 62 and 63: Ares V Engines and Thrust Structure
Page 64 and 65: Ares V Thrust Structure ShowingAtta
Page 66 and 67: RS-68 Liquid Fuel Engine for Ares V
Page 68 and 69: Thrust StructuresActualThe Engine a
Page 70 and 71: Comparing the Bottle Rocket and the
Page 72 and 73: Launch Testing Station
Page 74 and 75: The Design ProcessThe Design Proces
Page 76: Test Results SheetDesignNumberThrus

Spacecraft Structures pdf - ER - NASA

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