MARINE AVIATION MUSEUM Quantico exits from I-95. Open through November 10, reopens May 10. Hours: Tuesday through Friday 10 to 4 and weekends 10 to 5; ARMY ENGINEER MUSEUM Fort Belvoir exits from I-395 (

Rusting away in front of the Marine Corps Aviation Museum at Quantico is a Russian T34 tank that was made in Detroit. The tank has nothing to do with the Marine Corps or with aviation. It's just there, and for some reason it is charming.

At the Army Corps of Engineers Museum at Fort Belvoir there is a German glass antipersonnel mine. It strikes a horrid, creepy note in an otherwise dry display, but the thing is fascinating in a sick-making sort of way, and seems somehow to belong.

It is the cluttered, eclectic quality of the two museums that makes them a treat worth the trip south on I-95, particularly if combined with a visit to Fredericksburg or a picnic at Prince William Forest Park. Unlike the vast monuments to museum science on the Mall, the Marine and Engineers museums reflect the personal tastes and whims of their directors and whoever has enough rank to get an item he likes included. The unpredictability is delightful.

The Marine museum will make the bigger hit with kids, because it has some gee-whiz stuff, including the single surviving Zero fighter plane used in the attack on Pearl Harbor. Other unique specimens are the last F4F Wildcat fighter in the world and the only flyable Japanese "Ohka" suicide bomb in the Occident.

All of the nine planes on display are in flying condition. "Our standard is total and authentic restoration," a museum spokesman said. "If we have restored an aircraft it is by definition flyable, although of course we would never risk any of these babies."

The museum is housed in 55-year-old metal hangars that are museum-pieces themselves. Among other things, they spent six years in Nicaragua during the second Marine intervention there (1927-33). The drafty rattletrap buildings are just the right setting, but because they are uneconomical to heat the museum is forced to close during the coldmonths. "Marines are tough," said the shivering receptionist one afternoon last week, "but we're not that tough."

November 10 will be the last day this season, and on that day there will be a bonus: The museum's new World War I section will be open to the public for the first time. "I promised it would open this season and it will, if only for the one day," said director Thomas M. D'Andrea. Among the "wind in the wires" biplanes are a reproduction 1911 Curtiss pusher, a DeHavilland DH-4 bomber and a Boeing FB-5 fighter.

A further bonus for the kids is the better-than-average chance that at least one train will come thundering past, because the aviation museum lies alongside the RF&P mainline. From inside the buildings it sounds very like an air raid.

The Army Engineers Museum is less flashy but more thought-provoking. Since Roman times, construction battalions have been as essential to war-making as assault troops, and the Corps has accomplished some astonishing things. There is a special kind of courage involved in clearing enemy beaches and building bridges to hostile territory before an attack. Not a few Engineers have died doing it, and their Hall of Honor is no less impressive than the Marine airmen's Hall of Fame at Quantico.

The museum soft-pedals the Engineers' civilian role as the dammers, rechannelers and "reclaimers" of the American landscape, probably because their busy-beaverishness is not so much appreciated as it once was. "Essayons" "Let Us Try") is the Corps motto, and they'll try anything. They built the Panama Canal after the French had abandoned it as impossible. After the Washington Monument has half-built they put a new foundation under it; they no doubt could straighten out the leaning tower of Pisa. The museum booklet mentions rather casually that the Engineers ran the Manhattan Project, which produced the atom bomb.

The scale of a routine Eningeer operation can be odd as well as awesome. An aerial photograph from the Vietnam War carries the caption: The 1st Engineer Battalion, in Iron Triangle, Operation Cedar Falls , 1967, cleared an area of foliage to form Engineer turreted castle design (the Corps insignia), 1 mile wide , 1/2 mile high . Nothing is said about what, if any, military purpose was served by skinning so much of the planet.

If anybody still remembers the battleship USS Maine, whose sinking provided such a convenient casus belli for the Spanish-American War, her wheel is on display at Fort Belvoir. The Engineers raised her from Havana Harbor in 1912. She was stripped, towed to sea and sunk, making it difficult to dispute the finding by a board of inquiry that she was blown up by a Spanish mine, as we claimed while we were seizing the territories of the Spanish Empire. No less an authority than Admiral Hyman G. Rickover in 1976 published a book asserting that the inquiry was a bunch of hooraw and that the Maine blew up internally and accidentally, but the Corps adheres to the official version.

Good thing, too. When you don't have to go into "Manifest Destiny" it makes that "splendid little war" at lot easier to explain to your children.