How does a hovercraft turn?

Question

I am supposed to make a small autonomous hovercraft for engineering class (in college). We decided to have a single styrofoam skirt and use the Lego NXT Set for all the work (sensors, motors, etc). As of now, we will have 2 fans at the back of the hovercraft for thrust. I was wondering, what we could do for turning the hovercraft. We have the following options for turning:

1. Have 2 thrust fans, and turn one of them off to turn in that direction direction (for ex. turn the left one off to turn left).
2. Have 1 small fan each on the front corners of the hovercraft in addition to 2 fixed thrust fans. Turn them on as needed to shift the hovercraft left and right.
3. Use rudders in the thrust fans to steer the hovercraft.

Which one do u think is the most effective way to steer the hovercraft (and why)? I have a feeling #2 might be best b/c it's like front wheel drive in cars. #1 and #3 are like rear wheel drive, although #3 appears pretty convincing... what do you think?

Answer 1

I would stick with the rudders. Although i have no experience in this matter i do consider myself mechanically inclined. i would be led to believe the front fans would be very clumsy. and the dual fans in the back would be to slow to steer. i look at airplanes,blimps and air boats all using a form of a rudder to steer.

Answer 2

The simplest solution is the “tank steering”, which have already been mentioned. Two (2) thrust fans are mounted on left and right side of the hovercraft. Their thrust vectors are parallel to the axis of the hovercraft. If you turn any of the fans off, the other fan will turn the hovercraft.

Answer 3

Option 1. It's the simplest and lightest.



If you don't get the control authority you want, you might try turning each fan toward the center a little (so the thrust vectors form a "V") to increase the turning moment.



Any chance you could do variable speed motors, or even reversible? Then you could set the controls up like a tank.

Answer 4

Like the air boats in Florida, use rudders in the air path. You can also partially block air flow to turn.

Answer 5

Just like the system they are using in VTOL aircraft (Vertical Take-off and Landing) Harrier jets.

Swarzeneggers "True Lies", seen the system works,concentrate on the sideward system.