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Micro RC Ornithopter
(28 August 2003) Vincent and Jin-Wook Lee of Seoul, Korea, recently developed a series of small electric RC ornithopters. The first model, shown here, uses a GWS B2C motor, home-made micro gearbox using micro servo gears, 7.4 volt, 110 mAh lithium polymer battery, JMP 2.3 or GWS micro receiver, JMP 5 speed control, and Wes-Tech LS-2.4 servo. Some parts from the Ornithopter Zone's Freebird kit were used, giving a total 28 grams flying weight and 39 cm wing span. Videos of the ornithopter show flight performance comparable to commercially available units. The second ornithopter used a floating trailing edge, which produces more lift. Following Caltech's Microbat experimental ornithopter, the Lees began with a 22:1 gear ratio, but later found 26:1 was better as it maintained level flight at 50% throttle (about 0.4-0.5 A, 3-4 watts). They invented a special mechanism so that both yaw and pitch controls are possible with only one LS-2.4 servo while turning. The Lees intend to build a smaller ornithopter with a 23 cm span, challenging Caltech's Microbat as the world's smallest RC ornithopter. The ornithopter was entered in a local micro air vehicle (MAV) competition, which featured one other ornithopter as well as other aircraft types. The Lees' ornithopter won 1st prize in the design report category and 4th prize in the endurance mission among some 34 MAVs. The Lees did not win 1st prize overall, as there were many fixed-wing MAVs in the 9-11 cm size range. However, their ornithopter received the most attention from the audience and from the national TV news report. |
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