Iran's wide-ranging bombing raids deep inside Iraq yesterday dramatized the assessment of U.S. military analysts that Tehran's Air Force can perserve for an extended period of hostilities in bombing, dogfights and air defense despite two years of revolutionary chaos and a total embargo on U.S. parts.

The reading by U.S. experts reflects the relatively small number of aircraft involved in the four-day-old Persian Gulf war and an expectation that Iranian commanders can, by improvisation and cannibalizing parts, keep at least some of Iran's large U.S.-equipped Air Force flying.

The Iranian performance in air clashes has surprised some civilian observers, mindful of the disorganized state of the country's military after two years of disruption and the halt in supplies of American spare parts since late last year.

For military experts familiar with Iranian equipment and capabilities, however, the Iranian showing has followed predictable lines given the number of aircraft amassed by the late shah before he was driven from power and the extensive training he bought for his pilots and officers.

"Even at half strength, they can probably put up a pretty good fight," said one U.S. military expert asked to assess Iranian chances against the Iraqi Air Force, which is trained and largely equipped by the Soviet Union.

"As the days go on, even the hours, they're not getting any stronger; they're even getting weaker," he added. "But as for how long they can go on, it could be a long time."

The calculation of Iranian capabilities include the high number of Iranian jet pilots and Air Force officers considerable experience in flying and maintaining the F4 phantom jet that is the mainstay of the Iranian Air Force and generally high technical abilities.

For the most part, however, sheer numbers constitute the Iranian's main trump in the struggle to keep attacking targets within Iraq and repel bombing raids by Iraqi jets.

Iran's Air Force stood at about 100,000 men at the outset of the revolution but has been cut to half that number by desertions and disruptions. Even with that drastic decline, however, it still stands at 50,000 -- nearly twice as many as Iraq's.

Similarly, Iran under the late shah had about 190 F4 Phantom jets. U.S. experts estimate only about 40 percent are still able to fly effectively. But, they point out, that still leaves 70 operational aircraft designed for attacking targets in enemy territory.

Moreover, they say, none of the Iranian attacks on Iraqi cities or oil installations has involved more than three or four planes at a time. Although U.S. sources are unable to say exactly how many sorties Iran has been flying over the last four days, the number is believed to be small, perhaps fewer than 20 a day.

This estimate tends to discredit the large numbers of kills being claimed by both sides and to scale down the level and intensity of the air war.

Iranian air defense has been provided mostly by F5 fighters, a relatively unsophisticated U.S.-made jet designed for defense, the experts said. The Iranian air force has about 150 F5's with slightly more than half of them ready to scramble against attacking Iraqi Migs, in the assessment of U.S. analysts.

The most advanced Iranian jet, however, is considered to be sidelined by the effects of the revolution. This is the F14, a high-technology air combat plane equipped with U.S.-made Phoenix air-to-air missiles.

Only half a dozen of the F14s are operational because of a lack of maintenance and the devastation of the F14 pilot corps in political purges carried out by the new Iranian government of Ayatollah Ruhollah Khomeini, an administration analyst estimated.

But the Iranian Air Force's main problem in confronting Iraq, an American analyst noted, is the lack of centralized command control to coordinate between various units and respond quickly to threats from advancing Iraqi forces on the ground or in the air.

In the long run, he said, this could prove to be a telling weakness.