An Unkindness of Ravens An Unkindness of Ravens An Unkindness of Ravens is a novel by British crime-writer Ruth Rendell. It was first published in 1985, and features her popular protagonist Inspector Wexford, and is the 13th entry in the series. On American publication, it was shortlisted for the MWA Edgar Award, alongside another Rendell novel, "The Tree of Hands", meaning she has the remarkable distinction of being one of only two authors in the award's history to have had "two" novels on the shortlist in any one year (the other being Charlotte Armstrong). "Ravens" was adapted as a play by theatre professor Joel
Specific impulse to impulse provided by external air that has been used for combustion and is exhausted with the spent propellant. Jet engines use outside air, and therefore have a much higher specific impulse than rocket engines. The specific impulse in terms of propellant mass spent has units of distance per time, which is an artificial velocity called the "effective exhaust velocity". This is higher than the "actual" exhaust velocity because the mass of the combustion air is not being accounted for. Actual and effective exhaust velocity are the same in rocket engines not utilizing air or other intake propellant such as