Ram air turbines

A ram air turbine for driving an electric generator in a missile, the turbine comprising a turbine housing having a flow passage for ducting the incoming ram air, a turbine wheel having blades to which the ram air is supplied from said flow passage, wherein the turbine wheel includes means actuated by centrifugal force upon an increase in the rotational speed of the turbine sheel for uniformly restricting the cross section of the flow passage to all of said turbine blades and thus the amount of ram air acting on the blades of the turbine wheel to an extent depending upon the rotational speed of the turbine wheel,

• wherein the turbine wheel is a radial turbine wheel having a protruding central hub portion and the incoming ram air is incident upon the turbine wheel along the axial direction and thereafter flows past the blades in a radial direction, and wherein the centrifugal force actuated means comprises a disc of cup shape and inverted relative to the axial direction of the incoming ram air, the central portion of said disc being attached to said protruding hub of said radial turbine wheel, said disc being manufactured from a resilient material which upon rotation of the turbine wheel allows straightening-out deflection of the cup-shaped disc due to centrifugal forces, the outer edges of the disc lifting from an undeflected position against the turbine wheel.