CONTROL RINGS

1 . A control ring for use in a gas turbine engine, the control ring comprising:

a control ring segment defining a centerline axis, wherein the control ring segment includes:

an inner diameter surface and an outer diameter surface; and

an internal cavity defined between the inner and outer diameter surfaces, wherein the internal cavity is configured to contain a material having a higher heat capacitance than the control ring.

2 . A control ring as recited in claim 1 , wherein the control ring segment includes a plug between the internal cavity and the outer diameter surface to enclose the internal cavity.

3 . A control ring as recited in claim 2 , wherein the plug is brazed into the outer diameter surface of the control ring segment.

4 . A control ring as recited in claim 1 , wherein the control ring segment is one of a plurality of control ring segments joined together to form a full control ring configured to be held in a control ring carrier for thermal isolation from an outer air seal.

5 . A control ring as recited in claim 1 , further comprising a fill material having a higher heat capacitance than the control ring disposed within the internal cavity.

6 . A control ring as recited in claim 5 , wherein the fill material is a fluid sealed inside the internal cavity.

7 . A control ring for use in a gas turbine engine, the control ring comprising:

a plurality of radially stacked rings, wherein each radially stacked ring includes a plurality of arcuate segments joined together to form the ring.

8 . A control ring as recited in claim 7 , wherein at least one of the rings is made from a different material from another one of the rings.

9 . A control ring as recited in claim 7 , wherein seams are defined between the respective segments of the radially stacked rings, wherein the respective seams of one of the radially stacked rings are circumferentially offset from the respective seams of the adjacent radially stacked ring.