The pilot and builder of the experimental airplane reported that in cruise flight about 1,700 ft above ground level, he felt a vibration that progressively intensified. He elected to make a precautionary landing at a nearby airport; however, he forgot to extend the nose landing gear, and the airplane’s nose contacted the runway surface during landing, which resulted in substantial damage to the lower fuselage. Post accident examination revealed that the composite propeller had shed a portion of its nickel-plated leading edge and exhibited damage consistent with delamination. Further examination by the propeller manufacturer revealed that the delamination was the result of heat damage and a total failure of the propeller was imminent. About 5 months before the accident, the pilot contacted the propeller manufacturer and provided photographs that revealed early stage delamination damage to the propeller. He was advised by several company representatives that the damage was the result of heat due to the location and proximity of the engine exhaust to the propeller, and that he should not continue to fly with that propeller.