It's aerospace defense fleet week on Wall Street as five large companies announce earnings Wednesday and Thursday. Shares of weapons and aircraft maker General Dynamics (GD) bombed early Wednesday after it missed analysts' estimates. But Textron (TXT), maker of Bell helicopters and Cessna jets, beat profit forecasts, although sales were lighter than expected. Lockheed Martin (LMT), Raytheon (RTN) and Precision Castparts (PCP) are on tap to