The Senate Armed Services Committee has directed Defense Secretary Harold Brown to draw a fresh blueprint of the Navy, with special emphasis on the kind of aircraft carriers that should be built.

Committee Chairman John Stennis (D-Miss.) complained at the start of this Congress that the White House and Navy leaders had proposed several different navies last year and that it was high time to clear up the confusion.

The committee, in its report on the Pentagon's money bill, will direct Brown "to conduct a comprehensive evaluation" of giant Nimitz aircraft carriers, medium carriers of about 50,000 tons and "mini" carriers half that size.

In case President Carter should reverse his recent decision against building any more Nimitz-class carriers, costing $2 billion each, the Senate committee added $81.6 million to the Pentagon's money request for fiscal 1978. The $81.6 million could be used to make a start on another Nimitz.

However, the Senate Armed Services Committee will stress in its report to be issued next week that the extra Nimitz money "in no way suggests" the committee favors building another carrier of that class.

Carter and Secretary Brown affirmed the decision of their predecessors against building another Nimitz after they reviewed the Pentagon's budget for the fiscal year beginning Oct. 1, 1977. They plan to build medium-sized carriers instead for planes that could take off and land on a short stretch of deck.

The House, after a number of lawmakers fought for another Nimitz, voted to go along with the switch to smaller carriers.

While going beyond the House in providing money for a Nimitz-class vessel, the Senate Armed Services Committee stopped far short of the House action when it came to voting money for civil defense. The House has authorized $134.8 million or $44.8 million more than the $90 million the Pentagon requested. The Senate committee voted only an extra $2.25 million to finance more civil defense research, including an emergency communication system.

Carter requested $35.76 billion to develop and buy airplanes, ships, missiles and tanks in the fiscal year beginning Oct. 1, 1977. The Senate committee, in writing a Pentagon money bill that is expected to go to the floor within two weeks, took these actions:

Added $127 million to Carter's request, bringing the procurement bill to $35.89 billion.

Kept the A-7 fighter program alive by adding $91.4 million to build more of the planes, even though the Pentagon recommended stopping production.

Voted to repeal the law requiring all big warships to be nuclear powered.

Directed that the planned number of generals and flag officers and civilians grades GS 12 through GS-18 be reduced by 6 per cent over the next two fiscal years.

Added $78 million to buy 360 Lance missiles with conventional warheads, a weapon the Pentagon does not want.

Deleted the $6.8 million the Pentagon required to develop binary chemical weapons.

Reaffirmed its support of building a military medical school in Washington and provided $900,000 for faculty research there.