Complex sentence: As for conventional layout, the propeller to ground clearance at takeoff is a design issue, aircraft of this type must include either taller main gear, a skid or ventral fin, a high thrust line, or a reduced propeller diameter.
Split into simpler sentences: As for conventional layout, the propeller to ground clearance at takeoff is a design issue. As such, aircraft of this type may include one or more of the following: taller (longer) main gear, skid or ventral fin, high thrust line, reduced propeller diameter.