Deploying the Air Force's MX nuclear blockbuster missile in a long tunnel where it would be moved from point to point would be "strongly detrimental" to the effort to control the arms race, according to a study issued yesterday by four scientists.

If land-based missiles must be made mobile so they would be difficult for the Soviet Union to hit, said their report, it would be better to give them "unlimited mobility" by putting them on powerful helicopters rather than hiding them in trenches.

but the best path to follow, they said, would be to limit "drastically" the testing of long-range missiles that threaten to destroy U.S. and Soviet land-based missiles.

If 200 MX missiles were hidden in trenches more than 10 miles long, their report said, the Soviet Union would have to worry about these highly accurate weapons knocking out their land-based missile force.

Rather than take that chance, said the scientists, the Soviets, in response to MX, might well resort to a "launch-on-warning" strategy that would call for firing their missiles at the first sign of attack.

MX not only would create "insuperable arms control problems" but would be vulnerable to the one-two punch of Soviet nuclear war-heads. The earth trench would not be strong enough to protect MX missiles inside, the scientists contended.

In contrast, the Soviets could keep track of helicopters carrying missiles around the United States and thus would not have to resort to a launch-on-warning strategy, they said.

"We conclude that basing modes of limited mobility that rely on concealment" like the MX "for improved invulnerability do not offer guaranteed long-term security and create insuperable arms control problems . . .

"The most cost-effective means of maintaining the present invulnerability of Russian and American deterrent forces through the next decade and probably somewhat beyond would be through an agreement to limit drastically the testing of long-range missiles."

The 64-page report was written by Michael B. Callaham, a research associate at the Program in Science and Technology, a program financed by the Ford Foundation; Bernard T. Field, physics professor at MIT and director of PSTIS; Evangelos Hadjimichael, professor of physics at Fairfield University in Connecticuand Kosta M. Tsipis, associate director of PSTIS.