British Harrier jets shot down at least 27 Argentine aircraft during the Falkland Islands conflict without a single loss in air-to-air combat, according to representatives of the manufacturer of the Harriers, British Aerospace Inc., who are visiting Washington to promote the company's advanced weapons systems.

Five Harriers were lost to groundfire and four crashed accidentally, said officials of the company, which is owned by the British government.

Surface-to-air missiles made by British Aerospace downed at least 26 Argentine aircraft, the officials said. Like the Harriers, many of the missiles were used in combat for the first time in the Falklands.

Ken Perkins, a retired British army general employed by the company, told reporters yesterday that long-range Sea Dart missiles scored at least eight kills, short-range Seawolf missiles got five or more aircraft and land-based Rapier missiles destroyed at least another 13.

Figures on how many of each missile were fired remain classified by the British Defense Ministry, according to a company official. But the company did say that British helicopters launched a total of seven antiship Sea Skua missiles and each one scored a hit, sinking one vessel and crippling the rest.

By the end of the conflict, the British had destroyed on the ground or in the air about 60 percent of Argentina's fixed-wing aircraft, according to British Aerospace.

The Argentines, in contrast, had destroyed five Harriers, or 12 percent of the British task force's 42 "jump jets," which can take off and land vertically. The British government did not reveal how many Harriers were used in the Falklands.

Argentine troops depended mainly on guns for air defense, Perkins said. In this role, "missiles are more effective than guns," Perkins said. " . . . The Falklands showed conclusively that this is true."

These figures are unofficial, according to the company. The British Defense Ministry will release an official account of the hostilities in a few weeks, the company said.

During yesterday's briefing, company officials stressed planes that were destroyed by British Aerospace products. One official said the sinking of the Argentine cruiser General Belgrano might be credited to British Aerospace too, because, he said, it was hit by a World War II-model torpedo the company had refurbished.

Military analysts are watching with interest as details emerge of how new weapons performed in the Falklands. Though the Rapier is believed to have been used in the Iran-Iraq war, company officials said the Harrier and the Sea Dart, Seawolf and Sea Skua missiles saw their first combat in the Falklands.

Perkins said Rapiers set up on hillsides overlooking San Carlos Bay, where the British landed, were actually fired downhill at Argentine jets that swept in at 50 to 100 feet over the water to attack anchored Royal Navy ships. Missile crews had to divert some of them after launch when the planes they were tracking passed behind British ships.

Perkins played down the effectiveness of sea-skimming, French-built Exocet missiles that the Argentines used. Of six fired at British vessels, only two struck their targets, a third struck a ship it was not aimed at and three missed altogether, he said.

After losing many planes to Sea Darts at high altitudes, the Argentines were forced to attack at low level, Perkins said, which helped render many of their sorties ineffective. Some bombs that struck British ships failed to detonate because they had not fallen long enough for automatic arming devices to work.

Though Harriers downed 27 aircraft, Perkins said, there were few extended dogfights. Argentine pilots, low on fuel after flying from the mainland 400 miles away, tried to skirt the British planes, drop their bombs and get out.