LINTHICUM, MD. -- Westinghouse Airship Industries Inc. will build the prototype of a new military blimp, company officials say.

The flying craft, to be 423 feet long and 136 feet wide, will be much larger than the familiar Goodyear blimp. The blimp will be designed to stay in the air for 30 days at a time with a crew of 12 to 15.

The blimp would provide continuous, 360-degree, long-range radar surveillance, officials said. Westinghouse Airships President J. William Phipps said, "They are not as vulnerable as they look. They don't pop like balloons."

The firm, which was awarded the contract by the U.S. Navy, is to complete the aircraft by 1992.

Awarding the contract comes after a three-year Navy study into the feasibility of using lighter-than-air craft with fleet groups for surveillance, airborne early-warning radar and communications. The Navy decided that by using new construction techniques and modern electronics, the airship could used as an "early warning radar platform" that could travel with surface ships and warn them against low-flying missiles.

Westinghouse Airship is a newly formed company, the result of a joint venture between Westinghouse Electric Corp. and Airship Industries Ltd. of Cardington, England.