Water turbine like a true turbine. Fausto Veranzio in his book "Machinae Novae" (1595) described a vertical axis mill with a rotor similar to that of a Francis turbine. Johann Segner developed a reactive water turbine (Segner wheel) in the mid-18th century in Kingdom of Hungary. It had a horizontal axis and was a precursor to modern water turbines. It is a very simple machine that is still produced today for use in small hydro sites. Segner worked with Euler on some of the early mathematical theories of turbine design. In the 18th century, a Dr. Robert Barker invented a similar reaction
Free-turbine turboshaft Free-turbine turboshaft A free-turbine turboshaft is a form of turboshaft or turboprop gas turbine engine where the power is extracted from the exhaust stream of a gas turbine by a separate turbine, downstream of the gas turbine and is not connected to the gas turbine (the exhaust airflow is what spins the turbine that is connected to the shaft hence the term "free"). This is opposed to the power being extracted from the power spool via a gear box. The advantage of the free turbine is that the two turbines can operate at different speeds, and that these speeds can