Lumpsum Contract

Hi Guru's,

My requirement is to create a Lumpsum Contract and the Release Order against the Contract should be in Partial as per the progress of the work.

Example: I have raised a Lumpsum Contract for Water Tank for a Value of 10,00,000/- and I need to pay the Vendor Basing on the Progress of the work, If he Completes 10% in a Month, We need to pay 10% of The Lumpsum Contract to the Vendor.

How to map this requirement.

Thanks in Advance.

Raju