embodiments aircraft 10 may employ any number of wings 14 empennage 16 may employ a single or multiple flight control surfaces referring to fig2 there are illustrated some aspects of a non limiting example of a propulsion system 18 in accordance with an embodiment of the present invention propulsion system 18 includes a gas turbine engine 20 as a main engine i e a main propulsion engine which includes an auxiliary turbine system 22 engine 20 is a primary propulsion engine that provides thrust for flight operations of aircraft 10 in one form engine 20 is a two spool engine having a high pressure hp spool 24 and a low pressure lp spool 26 in other embodiments engine 20 may include three or more spools for example and may include an intermediate pressure ip spool and or other spools in one form engine 20 is a turbofan engine wherein lp spool 26 is operative to drive a propulsor 28 in the form of a turbofan fan system which may be referred to as a turbofan a fan or a fan system in other embodiments engine 20 may be a turboprop engine wherein lp spool 26 powers a propulsor 28 in the form of a propeller system not shown e g via a reduction gearbox not shown in still other embodiments propulsor 28 may take other forms such as a helicopter rotor or tilt wing aircraft rotor.