WASHINGTON, April 23 (Reuters) - Northrop Grumman Corp on Wednesday reported a higher-than-expected quarterly profit despite a drop in sales, and the U.S. weapons maker raised its earnings forecast.

Northrop, which makes unmanned planes, the B-2 bomber and a host of electronic equipment, said net income rose to $579 million, or $2.63 per share, in the first quarter from $489 million, or $2.03 a share, a year earlier.

Analysts polled by Thomson Reuters I/B/E/S had expected a net profit of $2.15 per share.

Revenue dropped about 4 percent to $5.84 billion, in line with Wall Street expectations.

The company raised its earnings-per-share outlook for the full year to a range of $8.90 to $9.15 and said it expected an operating margin of about 13 percent, compared with an earlier forecast of 12 percent.

(Reporting by Andrea Shalal; Editing by Lisa Von Ahn)