An inlet manifold for a multi-tube pulse detonation engine includes a vaneless diffuser disposed in a first zone to collect an air discharged from a compressor; a vaned diffuser including a plurality of guide vanes disposed in a second zone to slow the air from the compressor; a plenum disposed in a third zone located next to second zone to provide the air from the compressor to chambers; and a splitter disposed in a fourth zone to split the air from the compressor into an airflow required by each pulse detonation tube for detonation.