How many letters does the top answer for “an airplane with an external propeller that is driven by a turbojet engine” have?

The most common answer is propjet (7 letters).

Crossword clue: an airplane with an external propeller that is driven by a turbojet engine

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

propjet 7 letters wn-def

an airplane with an external propeller that is driven by a turbojet engine

turboprop 9 letters wn-def

an airplane with an external propeller that is driven by a turbojet engine