Inside Unmanned Systems

DEC 2016-JAN 2017

Inside Unmanned Systems provides actionable business intelligence to decision-makers and influencers operating within the global UAS community. Features include analysis of key technologies, policy/regulatory developments and new product design.

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56 unmanned systems inside   December 2016/January 2017 AIR NEW TOOLS ker said. "Boeing, Lockheed, Airbus and other big aerospace companies all have their own in-house tools for developing aircraft that the average Joe doesn't have access to without ex- pensive licensing fees." Other Software There are other free aircraft design software packages out there, such as AVL from MIT, "probably the most widely used tool that is the most similar," Hunsaker said. "It's very power- ful, and used by a lot of designers. However, it's all command-line interface, and requires a pretty significant learning curve to get into." Commercial aircraft design packages often analyze geometries using computational f luid dynamics (CFD) to analyze f luid f low over models. "The advantage of that is that you can handle extremely complicated geometries," Hunsaker said. "The disadvantage is that it's extremely slow and extremely computationally expensive, and it's hard to automate. There are free versions of CFD code—NASA has CFD that U.S. citizens can use—but it's extremely laborious to get solutions from it." In contrast, MachUp uses numerical lifting- line algorithms that can handle viscous effects. "These computations are much more simplis- tic—they're not as high accuracy, but they're extremely fast, and can give credible results for really low cost," Hunsaker said. "With the ini- tial design of the aircraft, you don't need that high an accuracy—you just want a ballpark so- lution today rather than in two weeks." "Numerical lifting-line methods are versa- tile in their ability to handle complex nonlinear geometries for lifting surfaces, as long as the aspect ratios for the wing are higher than four or five," aircraft designer Samuel Weiss said. The long, narrow wings of most passenger jets and light aircraft have an aspect ratio great- er than four or five, whereas the short, wide wings of a plane such as the Concorde have a very low aspect ratio less than four or five. MachUp code is much more limited in terms of computer-assisted design (CAD) capabilities than commercial packages. "It's not a full CAD modeler," Hunsaker said. "However, you can very easily create a model in seconds instead of hours." What Users Think MachUp's database of users suggest that near- ly 3,000 users have signed up to make use of MachUp in the past two years, including peo- ple from dozens of companies and aerospace engineering departments and schools, such as MIT, Virginia Tech, and Embry-Riddle Aero- nautical University, the world's largest univer- Photo courtesy of MIT CSAIL, Jason Dorfman and Rendering courtesy of Utah State University Software for 'bunnycopters' and other custom drone designs A new system from MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) enables users to design, simulate and build custom drones with unusual characteristics—like the varied-height rotors of the 'bunnycopter.' "Adding more rotors generally lets you carry more weight, but you also need to think about how to balance the drone to make sure it doesn't tip," said PhD student Tao Du, the first author on a paper about the CSAIL system. "Irregularly-shaped drones are very difficult to stabilize, which means that they require establishing very complex control parameters." CSAIL's system lets users design drones by choosing from a database of parts and specifying their needs for things like payload, cost and battery usage. The software computes the sizes of design elements like rod lengths and motor angles, and looks at metrics such as torque and thrust to determine whether the design will actually work. "This is the first system in which users can interactively design a drone that incorporates both geometry and control," says Nobuyuki Umetani in an MIT press release. Umetani is a research scientist at Autodesk, Inc., and not involved in the paper. More information: d/0B9HHfYresOgRRi1Zb21IMEpoWHc/view?usp=sharing

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