The helicopter whirred out of the horizon, skimmed over towering pines and spruces, and sent the ducks that had been swimming lazily in a nearby pond scurrying off in a flurry of urgent ripples.

It buzzed over the Alpine-style base lodge and set down on a landing pad at the base of 2,000-foot Mt. Cranmore, only yards from the roller coaster-like "mountain slide" and the world's largest dual-tramway Ski-mobile.

Two men in tracksuits, each bearing an armful of rackets, alighted. Another pair of players had made their grand entrance for a match in the $175,000 Volvo International Tennis Tournaments, which enthused locals call "the Wimbledon of the Woods."

It is not quite that exalted yet, surely but in only six years the Volvo tournament has gained an international reputation for good tennis with irresistible ambience.

The Mt. Washington Valley has become the globetrotting net set's Cathedral in the Pines. A Japanese tennis magazine featured it in 10 fullcolor pages of postcard scenes. Our national magazine fondly dubbed the tournament "the All-Natural, Maple-Flavored, Crunchy Granola Open."

It is, quite simply, a little country tournament that went big-time, bringing players of international standard to a bucolic setting in the White Mountains of New Hampshire. The pros are treated to a week of homespun hospitality and scenic R & R, while the wide-eyed townspeople enjoy an unaccustomed place in the sporting sun.

The permanent population of North Conway is less than 6,000. The nearest major population centers are Portland, Maine (a 1 1/2-hour-drive), Manchester, N.H. (2 hours) and Boston (3 1/2 hours), but last year 56,002 spectators attended the Volvo, and that total should be surpassed today.

Enough New Hampshirites and out-of-state visitors (700,000 tourists per week vacation in the state during the summer season) make their way to the Mt. Cranmore Tennis Club to back up narrow access roads for miles on the mornings of the final rounds. It was this unexpected traffic jam in the wilderness that necessitated the Whirlybird Express: the helicopter that shuttles players from the front lawn of their hotel to the rustic 10,000-seat stadium cut into Cranmore's Sylvan south slope.

The tournament doesn't have Wimbledon's prestige or 101 years of tradition, but it does have distinctive features.

Instead of strawberries and cream, "Whoopeee Pies" are sold under lime-and-navy-stripped concession tents. These are home-baked layers of fudge cake wrapped in the shape of yoyos around gooey pastry cream. Homemade, too, is the maple syrup presented in crockery jugs to the wives of players on arrival, compliments of New Hampshire's Chief of Sap - Gov. Meldrim Thomson.

The nonpareil attraction, however, is the scenery, which no other U.S. Summer Circuit tournament can match. After a succession of sweltering Cincinnatis, Washingtons and Louisvilles, players find in the pure air of New England's scenic "north country" a shimmering vision: three European-style red clay courts, with the majestic Presidential Range and the fringes of the White Mountain National Forest as a backdrop.

"I think all the players love coming here. It's such a unique atmosphere," said Tim Gullikson of Onelaska, Wis. "You're up in the mountains, looking down at these nice trees. It's such a tranquil, peaceful site. And the people are ultra-friendly. I think players respond to a friendly place."

The north country fans are a hearty breed.On Friday morning 6,000 sat through a persistent drizzle to watch quarterfinal matches. Most had traveled long distances for a glimpse of the players they usually see only on television, and they were rewarded as the overcast lifted and the sun shone gloriously throughout the afternoon, until other stars came out in the cool of night.

When the weather is agreeable, the Volvo tournament is a pleasant as an old-fashioned family outing. Spectators wander from the stadium and spread out lunches on grassy hillsides. Picnic tables are provided under shady groves. Youngsters cool their feet in the pond and feed the ducks as their parents repair to the "cocktail tent."

Players relax on the chaise lounges outside the plush camper that serves as their on-sit hideaway, they toss frishbees on the mountainside between matches, take their families or girlfriends for morning rides on the Conway Scenic Railroad, and ride the Skimobile to steak cookouts at Cranmore's summit house.

Few had the nerve to try hand gliding, but many hurtled down the twisting, stainless steel track of the "mountain slide" in metallic sleds, or indulged themselves in more relaxing pursuit: a round of golf at a local course, or some fishing in mountain trout streams.

"I caught a handful of rainbows the other morning, before coming out to call line," beamed Rev. Merie Irwin of New Jersey, one of many officials who work the tournament on their vacations. "Let's face it, you can't do that at the U.S. Open."

Some umpires, such as George Parker of Princeton, Mass., don broad-brimmed straw hats before ascending their high chairs of authority, and wear bermuda shorts and knee socks under their blue blazers.

The Volvo tournament grew out of a modest $5,000, four-man exhibition tournament originated by promoter Jim Westhall in 1970 at the Mt. Washington Hotel in Bretton Woods, N.H., 35 miles to the north. Rod Laver - the touring pro at the time for the rambling old Edwardian Hotel, which gained fame as the site of the 44-nation International Monetary Fund Conference in 1944 - brought along three fellow Australian pros for what he called "a little country hit."

The Bretton Woods tournament had grown into a 32-man, $25,000 Grand Prix tournament when Volvo of America came aboard as the sponsor in 1973. The prime attraction was the stunning setting - a natural amphitheater at the base of Mt. Washington - and such homey personalities as septuagenarian Cliff Door. "the Fishing Postmaster," who closed his stamp window at 11 a.m. each morning and would not reopen it until he had taken the legal limit of trout from the Ammonoosuc River.

When the cosponsoring Mt. Washington Development Company went bankrupt after the 1974 tournament, tournament director Westhall found a new location and cosponsor in the Mt. washington Valley Chamber of Commerce. The stadium was bulldozed into the mountains, and the tournament has thrived, thanks to Westhall's energetic year-round promotion and the efforts of a small army of volunteers.

It is hardly conceivable that there could be anyone in the state who does not know about the tournament. All the players are fully informed about it, because Westhall has been an evangelical recruiter, salesman and image-builder from the outset.

But for all its sophisticated organization and promotion, it is its smalltown flavor and charm that makes the Volvo tournament unique, and keeps people coming back.

"The tournament has brought a touch of the big leagues to the north country," noted one volunteer this week, "and the big leaguers like it as much as we do."