Gray Eagles : <i> by Duane Unkefer (Beech Tree: $17.95; 467 pp.) </i>

You really had to be there, as a hunter or the hunted, to fully understand man’s private love of war and the orgasm of combat.

Whether fighter pilot or commando, sniper or submariner, it has to do with being young and vital when a man is more willing to ride physical strength and mental quickness to within a whiff of losing his life. To teasing all odds against another total stakes player. To feeling immortality by surviving the purest of enemies; death and oneself.

There’s even a sense of the splendid attached to this rare rite of manhood and a correlation between combat and blood sports. Add the dimension of ephemeral adventure and you have the absolute beguilement of the experience. As screenwriter Harold Jack Bloom once wrote for the character of a graying gunfighter resigned to a final challenge: “Where are you going that’s better than where you’ve been?”

It’s not an easy mentality to understand. It’s even harder to express without tripping over John Wayne. But Duane Unkefer has caught it well in a book that is about as plausible as anything by Rambo, but as grand fantasy is as fascinating as flying fiction gets.

The Gray Eagles are eight ex-Luftwaffe fighter pilots who transitioned from World War II to duller but safer lives as industrialists, aviation executives, concert viola players, Lufthansa captains, car salesmen and businessmen. All were aces. All share a niggle common to every sore loser since Aristodemus at Thermopylae: “If we had it to do all over again. . . .”

So, as Lee Marvin gathered the Dirty Dozen and Yul Brynner collected the Magnificent Seven, ex-Luftwaffe Major Theo Heinrich hatches his Gray Eagles.

Their Staffel forms at a home near Phoenix. They get drunk on champagne and cognac in fine crystal while listening to Strauss. They wear yesterday’s jackboots and uniforms. They toast past missions and old victories and scoff the wife who cannot understand such fascinations.

Yet there’s more than benign pride and Nazi nationalism within this group. For a variety of motives--revenge, ego, lost youth, boredom, money--they have agreed to refly yesterday. And they will do it in the same planes with hot guns against as many of their old American enemies they can flush from military retirement.

So, 30 years over the hill, in eight ME-109Gs modernized and restored in secret at a dirt and scrub airstrip, the Luftwaffe’s last unit begins training for a final sortie to victory and recognition.

And, wouldn’t you know it, when they announce their existence and intentions by shooting up a fly-in of World War II warbirds at Chino Airport and strafing Williams Air Force Base near Phoenix, they succeed in stirring up Roger Lowen, an Air Force leftover from the grim old days.

Lowen is on the staff of the Confederate Air Force in Harlingen, Tex. He flies an air show routine with a group of P-51 Mustang fliers. When it comes to lusting after yesterday, Mustang drivers are no different than Messerschmitt pilots . . . and any reader worth his weight in Steve Canyon comic strips will know what comes next.

This is a bulky, somewhat overwritten book in need of serious editing to tighten the text and lighten the repetition. Some of the characters need sorting out, maybe dumping, because eight Luftwaffe men and an equal number of Mustang pilots, to say nothing of supporting roles, will have readers skipping the bit players.

On the other hand, Unkefer’s descriptions of flying fighters, from their smells to their feel, are quite glorious. His technical research is accurate and well applied. But in penetrating the soul of men who missed out, or men who crave to go back because combat was their spiritual apogee, the author is a quiet master.

One suspects that Unkefer has been there.