In a bid for increased efficiency with speed , a development of the `` turbofan '' and `` turboprop '' known as a propfan engine was created that had an unducted fan .
ADP DET NOUN ADP VERB NOUN ADP NOUN , DET NOUN ADP DET `` NOUN '' CCONJ `` NOUN '' VERB ADP DET NOUN NOUN AUX VERB DET VERB DET ADJ NOUN .