A turbomachine includes a rotatable annular outer drum rotor connected to a first plurality of blades. Each of the first plurality of blades includes a blade root portion secured to the rotatable annular outer drum rotor. Each of the blade root portions includes one or more structural radial retention features for radially retaining each of the blade root portions within the rotatable annular outer drum and one or more axial retention features for axially retaining each of the blade root portions within the rotatable annular outer drum.