Spacecraft Structures pdf - ER - NASA

44 – NASA Engineering Design Challenge: Spacecraft Structures 20079. Modifications and ExtensionsChanging the Cardboard PlateThe thrust structure model has been tested in a number of permutations withsatisfactory results. The challenge seems to have the optimal level of difficultywhen only one cardboard square is used, and it is placed at the top of the structure.However, you may wish to use an additional piece of cardboard on thebottom of the structure. This will make the structure stronger, but will also make itmore difficult to see the results of specific loads on the structural members. Youmay also wish to use a different shape, size, or thickness of cardboard or givestudents the option of modifying the cardboard. Doing away with the cardboardaltogether will make the challenge much more difficult.Allowing RepairsIf students discover the beginning stages of a design failure before they havesuccessfully launched three times, they can be allowed to stop testing and repairtheir design. A team electing to repair its design should go to the end of the testingqueue. The team should also weigh its model again before testing, record thenew mass, and record the design changes on the Design Specifications Sheet.Increasing the Rocket MassYou may find, especially with advanced students, that students reach a plateauin reducing the weight of their structure. At this stage, you may want to addadditional design constraints to increase the challenge. The most obvious modificationwould be to add mass to the rocket.Limiting Designs by CostMass reduction is not the only goal in spacecraft design. Engineers must alsostrive to lower costs.Ask students to brainstorm about what NASA engineers must do to reduce thecost of getting to space. Showing a model of the Ares V or referring to a posterwill be useful in stimulating student ideas. You might want to discuss such factsabout the Ares V as how much fuel it uses, which parts are reusable, and whichare not, etc. Possible answers include: Make sure all the parts can be reused,make the vehicle lighter so it uses less fuel, use less expensive materials, make itmore durable so you do not need to do much to it to prepare for the next launch,make a better engine that uses less fuel, make the engine more powerful so youcan carry more on a single launch, use less expensive fuel. Students are lesslikely to come up with process ideas for cutting costs such as designing fasterand testing more efficiently.Assign a cost to each material and start students with a set budget. Allowstudents to purchase materials. You may also attach a cost to testing eachdesign. Students must stay under budget while designing the thrust structuremodel. Compare designs from teams on the basis of weight and cost. Havestudents find the ratio of cost to weight for each design and plot the results ona graph.