Commercial jet afternoon flight from chicago to milwaukee. took window seat few rows ahead of emergency exit. looked out window on takeoff to see city, saw flattened rectangular object with triangular nose and small winglets alongside our jet wing. object kept pace as jet ascended, then pulled ahead so i saw three orange glows at end of object, but no exhaust and no wavering air from heat waves. stunned, then curious, got so into watching it, did not mention to other passengers. thought probably military drone test, took a break for a few minutes, looked back, it was gone.