The Pentagon and a ranking House Republican traded fire yesterday on how ready U.S. warplanes are to go into battle.

Pentagon spokesman Thomas B. Ross put the figures at 80 percent for the Air Force and 70 percent for the Navy, while Rep. Jack Edwards (R-Ala.) stuck to his figure of about 50 percent for tactical aircraft in both services.

The issue is expected to be argued anew today at a closed hearing of the Senate Armed Services Committee.

Ross said his higher percentages reflect "the number of planes that could carry out their missions in time of conflict," conceding that "by another standard a limited number of planes are at the level of readiness reported by Congressman Edwards."

The other standard reflecting only about 50 percent of the planes ready to go represents "virtually flawless functioning of all parts and all components at all times," Ross said.

Edwards said Ross' explanation "sounds like so much Pentagonese. Using the proper standard of mission capable, which means aircraft full-up, ready to go, only about 50 percent of them are ready.

"I'd love to be proved wrong," Edwards continued, "but I'm sticking to 50 percent." He added the readiness problem is aggravated by the lack of an adequate industrial base in the United States to produce spare parts for the military in a hurry.

He said the Defense Department has followed "an erratic policy of procuring weapons and spare parts." The military's industrial base cannot improve significantly until Pentagon procurement policy stablizes, Edwards said.

Defense Department figures do show an up and down pattern of buying first-line fighter planes. For example, the current program calls for buying 60 Air Force F15 fighters for $1.05 billion in fiscal 1980, or $17.5 million each, and 30 in the fiscal 1981 for $869.7 million, or almost $29 million each. Some of that increase stems from losing the savings from a larger production run.

Defense Secretary Harold Brown had said F15 production was stretched out to keep the line open for a longer period.

Pentagon officials last night put some of the blame on Congress for decreased military readiness. They said that since fiscal 1977 Congress has cut appropriations to spare parts and other operations and maintenance requests by $2.8 billion. The same operation and maintenance account has been reduced by $7.9 billion over the past 10 years, added Pentagon officials in explaining why military forces have had a difficult time keeping ready for war.

The argument between the Pentagon and Edwards was touched off by an article in yesterday's Washington Post in which the congressman decried the lack of readiness of aircraft, charging that the policy has been to stress buying new planes rather than fix the ones already on hand.