Answers: If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix i and o stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity Vi=V0B.
(A) is self-operating at zero flight speed (X) (B) is not self-operating at zero^flight speed ()
(C) requires no air for its operation (X)
(D) produces a jet consisting of plasma (X)
(E) none of the above (X)
Answers: Ram-jet engine is not self-operating at zero^flight speed.