SILENT WINGS by Gerard M. Devlin (St. Martin's: $27.95; photographs). It is quite clear from "Silent Wings" that the author is quietly apalled by the silent treatment history has given American glider pilots and their whispering war. Equally apparent--for those who care to fly between the lines--are the reasons why fellow airmen and World War II chronicles have overlooked at worst and looked down on at best, the exploits of 6,000 GIs who flew the canvas-covered Wacos. Most of the pilots were washed-out power fliers or enlisted men upgraded to the oddball rank of Flight Officer for glider operations. Their troop-carrying missions accompanying the Sicily, Burma, Normandy, Bastogne, South of France and Luzon campaigns weren't exactly roaring military successes. And it was definitely against the spirit of things aeronautical, sniffed Real Pilots of Real Airplanes, to embark on one-way missions that always ended in crash landings. Fortunately, in this finely researched, well reported history, author Gerard Devlin gives the glider pilot his permanent due--as a willing warrior cast by skimpy training into an almost experimental form of combat aboard an airplane with absolutely no firepower beyond spit and all the protection of a paper sack. As Gen. William C. Westmoreland notes in his foreword: "It was their awesome responsibility to repeatedly risk their lives by landing heavily laden aircraft containing combat soldiers and equipment in unfamiliar fields deep within enemy-held territory, often in total darkness. They were the only aviators during World War II who had no motors, no parachutes and no second chances." Theirs then, was a form of flight that mere power pilots were carefully trained to avoid. So may 6,000 heroes be remembered.