Unkindness Of Ravens Unkindness Of Ravens Unkindness Of Ravens is an Irish gothic rock/metal band formed in 2014 in Tipperary, Ireland. Their debut album "Under Stolen Skies" was released in November 2015 on now defunct label Dura Gesta Records [] based in Michigan in the United States. The band's first single "Leanan Sídhe" was released simultaneously with an accompanying video which explored themes around ancient Irish mythological characters and was filmed in The Burren and Slieve Bloom Mountains. The band is fronted by Darren Keegan and the band's style has been described as "melancholic and dramatic." The band was created by Keegan with
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