Red Wings forward Nate Danielson won a puck battle in the offensive zone and fed Michael Rasmussen behind the net. After trying to jam the puck past Joseph Woll, Rasmussen passed it through the crease for Copp, who finished from the doorstep.
Anton Johansson scored his first NHL goal, and Daniil Tarasov made 17 saves for Detroit (2-3-2), which had lost three games in a row (0-1-2).
Matvei Michkov scored, and Joseph Woll made 24 saves for Philadelphia (0-6-3), which extended its franchise-record winless streak to start a season to nine games.
The Flyers took a 1-0 lead at 17:32 of the first period when Michkov swatted the puck in at the right side of the net.
Johansson tied it 1-1 at 4:31 of the second period, finishing off a 2-on-1 with Dylan Larkin and scoring with a one-timer from the inside edge of the left face-off circle.
Johansson is the third Red Wings player to score his first career goal this month, joining Michael Brandesgg-Nygard and William Wallinder.
The Flyers nearly took the lead late in the second with a short-handed goal, but Tarasov stopped Noah Cates on a 2-on-1 with 21 seconds left.
