An gas turbine engine for an aircraft includes, in axial flow sequence, a compressor module, a combustor module, and a turbine module, together with a first electrical machine rotationally connected to the turbine module. The combustor module has a combustor volume V (cm3). In use, at a full power condition, the gas turbine engine has a maximum corrected core flow Q (m3/sec), and a ratio T of:




T
=


(


Maximum
⁢

Corrected
⁢

Core
⁢

Flow

=
Q

)


(


Combustor
⁢

volume

=
V

)






is in a range of between 450 and 2,500.