The pilot of the gyroplane reported that, while practicing simulated engine out landings, he "experienced" a sudden loss of lift during the flare due to a "possible strong wind shear". The gyroplane then dropped about 4 ft vertically, he attempted to recover with full power, but the gyroplane landed hard during. Subsequently, the propeller struck the ground, the gyroplane "bounced" left, and the rotor impacted the ground and sheared. The gyroplane sustained substantial damage to the main rotor and mast. The pilot reported that there were no preaccident mechanical failures or malfunctions with the gyroplane that would have precluded normal operation. The pilot reported the weather at the accident airport, about the time of the accident, was wind 300° at 12 knots, gusting to 15 knots. The pilot landed the gyroplane on runway 35.