Who invinted the plans for submarine and helicopter?

The concept of the submarine dates back to the 16th century, with early designs attributed to figures like Leonardo da vinci; however, the first practical submarine was developed by Dutch inventor Cornelis Drebbel in the early 17th century. The helicopter's design evolved over time, with significant contributions from various inventors, but Igor Sikorsky is often credited with creating the first successful practical helicopter in the 1930s.