This week, four Aerospace and Defense stocks are improving their overall ratings on Portfolio Grader. Each of these stocks is rated an “A” (“strong buy”) or “B” overall (“buy”).

This week, CPI Aerostructures (AMEX:CVU) is showing significant improvement as the company’s rating hops from a C (“hold”) to a B (“buy”). CPI Aerostructures engages in the contract production of structural and other aircraft parts for prime defense contractors, the United States Air Force, and other branches of the armed forces. In Portfolio Grader’s specific subcategories of Earnings Growth, Cash Flow, and Margin Growth, CVU also gets A’s. The stock currently has a trailing PE Ratio of 7.10. For more information, get Portfolio Grader’s complete analysis of CVU stock.

This week, GeoEye’s (NASDAQ:GEOY) ratings are up from a C last week to a B. GeoEye is a premier provider of imagery, imagery information products and image processing services. For more information, get Portfolio Grader’s complete analysis of GEOY stock.

This week, DigitalGlobe (NYSE:DGI) is making solid headway. The company’s rating improves to an A (“strong buy”) from last week’s B (“buy”) rating. DigitalGlobe provides commercial earth imagery products and information services worldwide. The stock price has risen 3.1% over the past month, better than the 6.9% decrease the S&P 500 has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of DGI stock.

SIFCO Industries (AMEX:SIF) earns a B this week, jumping up from last week’s grade of C. SIFCO Industries is engaged in the production and sale of a variety of metalworking processes, services and products produced primarily to the specific design requirements of its customers. For more information, get Portfolio Grader’s complete analysis of SIF stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.