The drumbeat of charge and countercharge about Stealth airplane secrets entered Day Two yesterday, with Defense Secretary Harold Brown accusing Ronald Reagan of "reckless distortions" in claiming that the Carter administration's disclosures on the project compromised national security.

"As a scientist," Brown told a hastily called news conference that began in his dining room at the Pentagon for the print media and moved to his office for television, "I am offended by Governor Reagan's cavalier attitude toward the facts.

"As a public official, I'm indignant at his reckless distortions."

Reagan charged Thursday that the Carter administration held a televised news conference about Stealth at the Pentagon Aug. 22 "for the sole purpose of aiding Mr. Carter's troubled campaign." The disclosures breached secrecy, he said, and dealt the nation "a grievous blow."

Stealth is the umbrella name for technology to make U.S. aircraft invisible to enemy radar. Brown disclosed at the Aug. 22 news conference that Stealth planes already had been flight tested and hailed the advance as a major breakthrough that "alters the military balance significantly."

The administration's disclosure about Stealth, Reagan charged in a campaign speech in Jacksonville, Fla., "has now given the Kremlin a 10-year head start on developing ways to counter this type of ultra-sophisticated weapons system."

Brown said Reagan was "incorrect," declaring that the details that would help the Soviets counter Stealth have not been disclosed by the Pentagon or anyone else.

The Stealth program, Brown said, "is still secure in its vital details." He repeated that he decided to publicize the existence of Stealth because a series of press leaks and the growing number of people involved with the program made it impossible to keep everything secret any longer.

"Given a program as important and valuable as this one," said Brown, "I believe it merited" the full-blown treatment of a nationally televised news conference rather than a modest statement confirming Stealth's existence.

He said he considered it part of his responsibility to make clear what U.S. advantages are militarily in relation to the Soviets.

This kind of disclosure about American technological advances, the defense secretary said, helps thwart "unwarranted denigration of U.S. capability."

Brown acknowledged that "I was not unaware political questions might be raised" about his holding a news concerence on Stealth. "That didn't govern me."

He said he notified "the appropriate people" at the White House that the Pentagon was going to hold a Stealth news conference, but he refused to state whether those people included President Carter. Brown said he told the White House "there would be political allegations."

"I'm not at all surprised it caused a storm," Brown said. "I guess I'm surprised at the size."

When asked if undercutting Reagan was not the real reason for going public on Stealth, he replied, "That was not my purpose." He said his motive "was to make it clear the United States remains ahead in technology . . . "

Brown said that he, rather than candidate Carter, was answering Reagan's charges because "the attack was directed at me personally . . . Not to respond to it might be seen as acquiescing in it."

At the White House, press secretary Jody Powell told reporters Carter rarely has been "more angry" than when he read Reagan's charges about Stealth.

"Any implication from Governor Reagan or anybody else that the president or secretary of defense acted in a manner that damaged the security of this country is wrong and is not responsible and goes far beyond the acceptable bounds of political partisanship," Powell said.

Reagan spokesman Lyn Nofziger said: "The facts speak for themselves, and I would refer Jimmy Carter and Jody Powell to the Congress if they need to refresh their memories. Jimmy Carter's anger is completely phony. This is just another one of his attempts to change the subject. We don't intend to let him do it."

In another news conference, four of Reagan's military advisers -- three Army generals and an admiral -- termed the administration's Stealth disclosures a "flagrant break of security."

"What this does is give the Soviets an opportunity to counter the American technology," said Adm. Thomas H. Moorer (ret.) former chairman of the Joint Chiefs of Staff. Other Reagan military advisers joining of the Joint Chiefs of Staff. Other Reagan military advisers joining Moorer in assailing the administration's revelations were Lt. Gen. Daniel Graham (ret.) former head of the Defense Intelligence Agency; Lt. Gen. Edward Rowny (ret.), former SALT representative for the Joint Chiefs of Staff, and Gen. Richard Stillwell (ret.).