Ike from the '80s: looking better; Eisenhower, the President: Crucial Days 1951-1960, by William Bragg Ewald Jr. Englewood Cliffs, N.J.: Prentice-Hall Inc. $12.95.

It is fascinating the way fashions in past presidents change. A few years ago it was stylish to put Dwight Eisenhower down there near the bottom with Martin van Buren and poor old James Buchanan. Now, as we look back at the comparative tranquillity of the 1950s, we are coming to realize that he was the right man to preside over and make less stressful the solstice-time between the stalemated Korean war and the nightmare of Vietnam.

William Bragg Ewald's new book on Eisenhower's eight-year stewardship gives substance to the restyling of Ike and adds luster to the legend. Ewald had an excellent vantage point from which to observe what he calls the "crucial days" from 1951 to 1960. For several of those years he served on the White House staff, and after Ike stepped down he helped the ex-President prepare the two volumes on his incumbency -- "Mandate for Change" and "Waging Peace."

What those books lacked in atmosphere, pen portraits, and intimate glimpses of history-in-the-making, the Ewald book now supplies in good degree. It makes no real attempt to be a chronological narrative, skipping around a good deal. But all the stirring and all the anxious moments are here, told more vividly than ever before. And there is deep affection -- but a merciful lack of hero worship -- for the good, steady, magnetic man that was Ike.

What emerges to a striking degree is Eisenhower's interest in the bold and creative, in the quest for peace: the Atoms for Peace proposal (1953); the Open Skies proposal, which caught the Soviets off guard at Geneva three years later; and the strengthening of NATO, which he did so much to bring to life. (He had created the military arm of NATO, SHAPE, Supreme Headquarters Allied Powers, Europe).

There are new insights on the bad times like the Suez crisis, too -- Suez being a prime example of how closely and well Ike and his craggy secretary of state, John Foster Dulles, worked in double harness. (Ewald is quite wrong in saying that aid for the Aswan Dam was cut off "largely on economic grounds." It was cut off because the Egyptians were playing the United States off against the Russians, and defying the US by procuring Soviet arms via Czechoslovakia.)

But it is Eisenhower's character that emerges as the core of the book. Ike was, we discover, surprisingly thin-skinned about criticism, and by the same token often unwilling to hurt people's feelings in direct confrontation. Here are some prime examples of these traits:

* Ike and his spokesman: Press secretary Jim Hagerty says to the President, "If I tell them that they'll eat me alive." Ike, chuckling, "Better you than me, boy. Now go out and tell them."

* Ike and McCarthy: We learn why the President chose to fight the rogue senator by indirection and never "roll in the gutter" with him.

* Ike and Nixon: Others give a brazen Nixon the word that the President doesn't want him on the ticket for a second term.

* Ike and the firing of Sherman Adams: Ike asks Meade Alcorn to do the job, saying, "This is the toughest, dirties assignment I could ever give a national chairman."

We also learn how Ike handled the uneven Emmet Hughes, a top speech writer who later became a Newsweek columnist, whose ambition ran like quicksilver through both terms. We discover how Ike's "fire and self-discipline" steadied him in the bad times.

The McCarthy episode still makes sad reading, for it is the one instance where Eisenhower's aloofness did great harm. No amends where ever made in his time in office for the lives which McCarthy's wild charges ruined. Ike's private showdown with the senator at the Pere Marquette Hotel, in Peoria, Ill., during the 1952 campaign may well have been a moment of sharp anger, as Ewald tells us it was. But in the words of newsman Ed Yoder, "it never played in Peoria. . . ." As Ewald makes very clear, Eisenhower did have a well-developed military instinct to protect his flanks. But his refusal to grapple with McCarthy is something neither time nor Ewald can ever explain away.

Access to the late Jim Hagerty's journal supplies a new vein of material that Ewald mines conscientiously and well. For Hagerty was closer to Ike for longer than anyone else. In default of his own memoirs, Ewald's admiring yet evenhanded study fills a large gap, and a very real need to set the record straight.