The Ride of the Valkyries is the music heard when the rockets launch at the REPCONN Test Site at the end of the Fallout: New Vegas quest Come Fly With Me, as well as on the Fallout 4 Classical Radio.
"The Ride of the Valkyries" is not the actual title of the music, but is the popular name for the beginning of Act III of Die Walküre, the opera by Richard Wagner. Due to a famous scene in the war movie "Apocalypse Now" this song is commonly thought to be an iconic sound of what many people call the greatest war movie on earth.
"Launch Music" is also a terminal that you can talk to in the REPCONN Test Site. However, you can only access this terminal if clipping is off. Find the room with the collapsed floor and three chalkboards. Find the chalkboard in the corner that has the desk and filing cabinets next to it. No-clipping through the wall will reveal a terminal that you can talk to, but all it says is, "What do you need?", and the only response you can say is "Time for me to go".