Coming off their divisional home win over the Cardinals, head coach Jim Harbaugh and the 49ers flew to M&T Bank Stadium for a Week 12 interconference duel with the Baltimore Ravens and their head coach (Jim's brother) John Harbaugh on Thanksgiving. San Francisco trailed early in the first quarter as Ravens kicker Billy Cundiff got a 39-yard field goal, yet the 49ers answered with a 45-yard field goal from kicker David Akers.  Baltimore struck back in the second quarter with Cundiff making a 23-yard field goal. San Francisco began the third quarter with a 52-yard field goal from Akers, but the Ravens opened the fourth quarter with quarterback Joe Flacco completing an 8-yard touchdown pass to tight end Dennis Pitta, followed by Cundiff nailing a 39-yard field goal.  The Niners tried to rally, but Baltimore's defense held on to preserve the win.. How long was David  Aker's longest field goal?