An engine core including a turbine, compressor, and a core shaft connecting the turbine and compressor; a fan located upstream of the engine core including a plurality of fan blades; and a gearbox. The gearbox is arranged to receive an input from the core shaft and to output drive to the fan to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox and includes a sun gear, a plurality of planet gears, ring gear, and planet carrier to the mounted planet gears. The planet carrier has an effective linear torsional stiffness and the gearbox has a gear mesh stiffness between the planet gears and the ring gear. A carrier to ring mesh ratio of: the ⁢ ⁢ effective ⁢ ⁢ linear ⁢ ⁢ torsional ⁢ ⁢ stiffness ⁢ ⁢ of ⁢ ⁢ the ⁢ ⁢ planet ⁢ ⁢ carrier gear ⁢ ⁢ mesh ⁢ ⁢ stiffness ⁢ ⁢ between ⁢ ⁢ the ⁢ ⁢ planet ⁢ ⁢ gears ⁢ ⁢ and ⁢ ⁢ the ⁢ ⁢ ring ⁢ ⁢ gear is greater than or equal to 0.2.