f17582d2_engine___Free_net_encyclopedia__Type
[Description] Turboprop engine drives one or more propellers. much like a turbofan but without ductwork [Advantages] Higher fuel efficiency, some designs are less noisy than turbofans, could lead to higher-speed commercial aircraft, popular in the 1980s during fuel shortages, [Disadvantages] Development of propfan engines has been very limited, typically more noisy than turbofans, complexity [Type] 
Propfan
Jet engine - Free net encyclopedia
Type