AERIAL FREIGHT TRAIN—This artist's conception of the Douglas CI32 giant cargo plane is the first official announcement of the U. S. Air Force's huge transport for quick supply of bases anywhere in the world.—(AP Wirephoto.) GIANT NEW CARGO PLANE CARRIES 200,000 POUNDS AT 460 MPH WASHINGTON (AP)-—The Air Force has unveiled a gigantic new cargo plane—the Douglas C132—which will have a speed of more than 460 miles an hour and be capable of carrying a 200,000-pound payload. This maximum load is double the lift of the C99, a transport version of the B36 and the largest American cargo carrier in existence. The new swept-wing C132 will have a moderate range when fully loaded. With a load of 100,000 pounds the big plane will have a range of 3,500 miles. It can operate from ruways of conventional length. It will be powered by four jet turbine-propeller engines which the Air Force says are of "new" design. It declined to give details but said that each engine produces the equivalent of about 15,000 horsepower. In announcing some deatils of the new craft yesterday, the Air Force also released photographs of a "mockup" of the plane under construction at the Tulsa, Okla., division of Douglas. The pilot's compartment is pressurized to permit high altitude operation without the use of oxygen masks.