The Pentagon has said in a public document that it wants $2.3 billion for an Air Force plane called Aurora but responded yesterday that the plane -- if it really is a plane -- is "classified."

The secrecy cloak slipped off the spending plans for Aurora when the Pentagon compiled its unclassified shopping list, known as the P1 document. The P stands for procurement.

Spending for Aurora, according to this public document, shoots up from zero this fiscal year to $80 million in fiscal 1986 to $2.27 billion in fiscal 1987. Reminded that Aurora has been put in the public domain by the Pentagon, an Air Force spokesman said his orders still were to say only: "It's a classified program."

The office of Pentagon spokesman Michael I. Burch would say nothing further.

Other Pentagon sources, however, said that Aurora may have some connection with the Stealth plane -- to be designed to hide from enemy radar -- but that the really big money for Stealth is held in a different secret account and goes far beyond $2.3 billion a year when it enters the production stage.

"If you think $200 million is high for one B1 [bomber]," one source said, "wait until you see the price tag for Stealth."

B1 bombers are coming off the Rockwell International production line in California, while Stealth is expected to be delivered early in the 1990s.

Stealth is being designed to make search radar beams slip over its body rather than be reflected back to gunners' scopes. This has prompted the Northrop Corp., builder of Stealth, to design almost all equipment to be carried inside the plane rather than present sharp angled surfaces that would reflect radar beams.

A number of lawmakers are concerned that the Air Force will starve the Stealth bomber, formally called ATB for advanced technology bomber, in favor of the B1 bomber now in hand.

Air Force Secretary Verne Orr tried to allay these fears by telling the Senate Armed Services Committee yesterday that "we have no internal plans whatsoever to buy the 101st B1 aircraft." The Air Force is seeking $5.9 billion for fiscal 1986 to buy the last 48 of its order of 100 B1s.

Orr added, "We seem to be making good progress" on the Stealth.