NASA last month unveiled plans to develop X-57, dubbed "Maxwell," an entirely electric-powered aviation-sized plane capable of reaching speeds of 175 mph, and its first X-plane -- piloted experimental plane -- in 10 years. The space agency's goal is to do for electric planes what Tesla Motors' (NASDAQ: TSLA) co-founder and CEO Elon Musk has done for electric vehicles: help them take off.Here's what investors -- including those in Boeing (NYSE: BA), Airbus (NASDAQOTH: EADSY), and Siemens (NASDAQOTH: SIEGY) -- should know. Continue reading