UFO with jet engine sound in Palmdale

Summary

In September 1955, a witness in Palmdale, California, observed a flat, rounded aerial object emitting a deep sound similar to a diesel engine, combined with a sharp tone like a jet engine. The object moved slowly toward the southeast, maintaining a consistent direction for 10 to 15 minutes. Despite the duration of the observation, no photos were taken and the object's identity remains unresolved.

The investigators considered the possibility of it being a test vehicle, but no confirmation was made. The object's description and behavior did not match known commercial or military aircraft of the time. The official report did not reach a definitive conclusion, adding mystery to this case.