Airplanes deploy revers thrusters when landing which are basically just shaped metal shields that move into place behind the engines to provide reverse thrust and slow the plane.
But adding a fan on a sailboat is seen as stupid and doesn’t work.
Airplanes deploy revers thrusters when landing which are basically just shaped metal shields that move into place behind the engines to provide reverse thrust and slow the plane.
But adding a fan on a sailboat is seen as stupid and doesn’t work.
Your confusion is justified. It shouldn’t work, all things equal.
I think it’s because the intake of a plane is more diffuse; it’s pulling air in from different directions. Meanwhile, the “reverse exhaust” is ejected from a smaller nozzle at higher temperature; it has a higher velocity, therefore more momentum to “push” the plane than the intake “pulling” it.
For the record, there’s a similar scheme for sailboats. Hook a fan in the air to a propeller in the water, and the wind imparts less momentum than the prop “pushing” on the water. Such a “rotary sailboat” can sail straight into the wind.