I guess this was Charlton's answer to DC's "Zardoz at Harvard."
Frank was the idol of millions of young boys! A few centuries ago, anyway. His stories first appeared in 1896. Wiki notes:
The model for all later American juvenile sports fiction, Merriwell excelled at football, baseball, basketball, crew and track at Yale while solving mysteries and righting wrongs. He played with great strength and received traumatic blows without injury.
A biographical entry on Patten noted dryly that Frank Merriwell "had little in common with his creator or his readers." Patten offered some background on his character: "The name was symbolic of the chief characteristics I desired my hero to have. Frank for frankness, merry for a happy disposition, well for health and abounding vitality."
There was a radio serial as well. The character has not been revived by popular acclaim or retooled for modern audiences. Probably just as well. They'd make him wear a helmet all the time.