Collapsible spar mandrel

1. A method of assembling a mandrel comprising:

assembling a plurality of members via interlocking features arranged at opposing edges of each member of the plurality of members to form a compartment, the assembled members having a collective outer surface that conforms to an inner surface of the spar; and

inserting a support member into the compartment formed radially inward from the assembled members, the support member making contact with a portion of each member of the plurality of members;

wherein each of the plurality of members comprises a respective tongue portion and groove portion to form an s-shaped pattern, wherein the groove portion is connected to a first surface at a first end and to the tongue portion at a second end, and wherein the tongue portion is connected to a second surface at a third end and to the groove portion at the fourth end.

2. The method of claim 1 , wherein each interlocking feature comprises the respective tongue portion and groove portion.

3. The method of claim 1 , wherein assembling the plurality of members comprises:

inserting the respective tongue portion of each member of the plurality of members into the respective groove portion of another member of the plurality of members.

4. The method of claim 1 , wherein the support member comprises a plurality of vanes extending radially outwardly from a center of the support member.

5. The method of claim 4 , wherein the support member has a number of vanes equal to a number of members of the plurality of members.

6. The method claim 5 , wherein inserting the support member into the compartment comprises:

sliding a respective edge of each vane into a respective groove of each member of the plurality of members.

7. The method of claim 1 , further comprising:

coupling a first sub-member to a second sub-member to form a member of the plurality of members.

8. The method of claim 1 , further comprising:

while the assembled mandrel is in a spar cavity of an uncured spar, sliding the support member out of the assembled mandrel; and

removing, upon removal of the support member, the assembled mandrel from the spar cavity.

9. The method of claim 8 , further comprising applying a pressure to an outer surface of the uncured spar while the mandrel is inserted in the spar cavity.

10. The method of claim 1 , wherein a first member of the plurality of members has a surface profile that conforms to an inner surface of a leading edge surface of the spar; and wherein a second member of the plurality of members has a surface profile that conforms to an inner surface of a trailing edge surface of the spar.

11. A method of assembling a mandrel comprising:

assembling a plurality of members via interlocking features arranged at opposing edges of each member of the plurality of members to form a compartment, the assembled members having a collective outer surface that conforms to an inner surface of the spar;

inserting a support member into the compartment formed radially inward from the assembled members, the support member making contact with a portion of each member of the plurality of members;

coupling a first sub-member to a second sub-member to form a member of the plurality of members;

inserting the assembled mandrel into a spar cavity of an uncured spar; removing, in response to the spar being cured, the support member from the compartment and

removing, upon removal of the support member, the assembled mandrel from the spar cavity;

wherein removing the assembled mandrel comprises sliding a single member of the plurality of members out of the spar cavity prior to removing a balance of the plurality of members.

12. The method of claim 11 , further comprising:

generating a computer-model of the surface of the spar;

determining a number of members of the plurality of members on the computer-model;

defining a model member for each of the determined number of members; and

additively manufacturing each of the members according to the defined model member.