Gas turbine engine

1. A gas turbine engine comprising:

a compressor, the compressor comprising a plurality of blades mounted to a hollow, annular compressor drum,

wherein the compressor comprises one or more electric storage devices mounted within the hollow compressor drum,

wherein the compressor comprises two or more compressor discs joined by a rim provided at a root of the compressor blades, to form the compressor drum, each compressor disc comprising a web extending radially inwardly from the rim, and

wherein the one or more electric storage devices are provided in a space defined by adjacent webs and the rim.

2. The gas turbine engine according to claim 1 , wherein the one or more electric storage devices comprises one or more of a chemical battery, a fuel cell, and a capacitor.

3. The gas turbine engine according to claim 1 , wherein the one or more electric storage devices are provided in a toroidal space defined by the adjacent webs and the rim.

4. The gas turbine engine according to claim 1 , wherein the compressor comprises a radially inner spool spaced from the rim.

5. The gas turbine engine according to claim 4 , wherein the one or more electric storage devices is mounted to the radially inner spool.

6. The gas turbine engine according to claim 5 , wherein the electric storage device comprises a capacitor, and the capacitor is wound around the radially inner spool.

7. The gas turbine engine according to claim 1 , wherein the gas turbine engine comprises an electric machine coupled to the compressor of the gas turbine engine.

8. The gas turbine engine according to claim 7 , wherein the electric machine is electrically coupled to the one or more electric storage devices.

9. The gas turbine engine according to claim 7 , wherein the electric machine comprises a synchronous electric machine comprising a stator having a plurality of stator windings, and a rotor comprising a plurality of rotor windings.

10. The gas turbine engine according to claim 9 , wherein the rotor windings are electrically coupled to the one or more electric storage devices.

11. The gas turbine engine according to claim 7 , wherein the electric machine comprises a permanent magnet electrical machine, comprising a plurality of permanent magnets mounted to one of a stator and a rotor, with the other of the rotor and the stator comprising a plurality of electrical windings.

12. The gas turbine engine according to claim 11 , wherein the electrical windings are mounted to the rotor, the gas turbine engine comprises one or more power electronics units configured to convert between AC current generated/required by the rotor windings and DC current provided/required by the one or more electric storage devices.

13. The gas turbine engine according to claim 7 , wherein the gas turbine engine comprises a fan located forward of the compressor.

14. The gas turbine engine according to claim 13 , wherein the electric machine is mounted between the fan and the compressor, and is configured to drive the fan, and may be configured to be driven by the fan.

15. A gas turbine engine comprising:

a compressor, the compressor comprising a plurality of blades mounted to a hollow, annular compressor drum,

wherein the compressor comprises one or more electric storage devices mounted within the hollow compressor drum,

wherein the gas turbine engine comprises an electric machine coupled to the compressor of the gas turbine engine, the electric machine comprising a permanent magnet electrical machine, comprising a plurality of permanent magnets mounted to one of a stator and a rotor, with the other of the rotor and the stator comprising a plurality of electrical windings, and

wherein the electrical windings are mounted to the rotor.

16. The gas turbine engine according to claim 15 , further comprising one or more power electronics units configured to convert between AC current generated/required by the plurality of electrical rotor windings and DC current provided/required by the one or more electric storage devices.

17. A gas turbine engine comprising:

a compressor, the compressor comprising a plurality of blades mounted to a hollow, annular compressor drum,

wherein the compressor comprises one or more capacitors mounted within the hollow compressor drum,

wherein the compressor comprises two or more compressor discs joined by a rim provided at a root of the compressor blades, to form the compressor drum, each compressor disc comprising a web extending radially inwardly from the rim, and

wherein the one or more capacitors are provided in a space defined by adjacent webs and the rim.

18. The gas turbine engine according to claim 17 , wherein the one or more capacitors are provided in a toroidal space defined by the adjacent webs and the rim.

19. The gas turbine engine according to claim 17 , wherein the one or more capacitors are wound around a radially inner spool spaced from the compressor rim.