Rockettes Of The Air -- Navy pilots demonstrate their skill in flying formation with Martin P4M-1 Mercators, long-range patrol airplanes. The big four-engine (two piston, two jet) planes built by The Glenn L. Martin Company for the Navy are in service with VP-21,a Fleet squadron based at the Naval Air Test Center, Patuxent River, Maryland. While the Mercators look like a twin-engine aircraft, each nacelle for Pratt & Whitney R-4360 piston engines also houses an Allison J-33 jet for additional power. and speed when needed. For their role as anti-submarine planes, Mercators are equipped with the latest electronic equipment for detection of the underwater raiders as well as armament for their destruction. P4M-ls may likewise be used for mine sowing, photo reconnaissance and other missions. November 5, 1950. (Photo by The Glenn L. Martin Company).