Thanks for the correction. "Heavy Lander" implies is can land a heavy load of something, such as a large number of crew or equipment/cargo. The side hatches are too small for cargo, so, perhaps there is a large, unseen hatch on the bottom of the ship to unload cargo containers? I does sit high off the ground. Additionally, it might tractor beam containers down through the open cargo hatch as the shuttle hovers above. The two side landing struts could also double as phasers for protection.^^ The shuttlecraft in “Mudd’s Passion” was known as a heavy lander. The shuttlecraft in “Slaver Weapon” was known as a long range craft.
The ship concept appears as an early TNG Runabout.