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I've had some interesing conversation over a possible design for a hovercraft. The design is that two propellers are pointed down, with a hole in the back of the craft. I believe this won't work but it has produced some very promising results in terms of how many penny roles it can hold. However, some of the time the craft spins in circles, and it also goes backwards. Why is this???

hmma wrote:I've had some interesing conversation over a possible design for a hovercraft. The design is that two propellers are pointed down, with a hole in the back of the craft. I believe this won't work but it has produced some very promising results in terms of how many penny roles it can hold. However, some of the time the craft spins in circles, and it also goes backwards. Why is this???

I have seen designs that have used two fans at the bottom that have worked. As for the spinning, I believe that the weight is not balanced or the airflow is not balanced. As for going backwards, I dont know how that happens, but I have seen it happen at competitions.

Would this fan work or is it not allowed since it is uses a brushless motor.
https://www.mouser.com/ProductDetail/?q ... WSaA%3D%3D

What is qualified as hovering, doesn't it have to actually lift up in the air and have a big difference or does just making it easily move across a surface?

samuel.barlow003 wrote:What is qualified as hovering, doesn't it have to actually lift up in the air and have a big difference or does just making it easily move across a surface?

I believe it just has to be visibly off the ground (comes back up if pushed down)

What if it kind of pushes down and comes back up, like if you had a paper plate or something and no skirt then it comes back up just a little bit.

samuel.barlow003 wrote:What is qualified as hovering, doesn't it have to actually lift up in the air and have a big difference or does just making it easily move across a surface?

Rule 3.b say: "b.The vehicle must levitate on a cushion of air as it moves down the track.Participants may be asked to demonstrate levitation by pushing the vehicle slightly down. If it then rises,it is levitating. Continuous contact of the inflated skirt with the base surface,occasional contact of other vehicle components with the base surface, or any contact with the inside edge of the side rails is permitted"

samuel.barlow003 wrote:Would this fan work or is it not allowed since it is uses a brushless motor.
https://www.mouser.com/ProductDetail/?q ... WSaA%3D%3D

This type is OK because the motor is embedded with the fan, If the motor was separate then not allowed

"Brushless motors and integrated circuits are not permitted unless they are an integral part of or embedded into commercially available fans used for cooling electronics or computers

MattChina wrote:

hmma wrote:I've had some interesing conversation over a possible design for a hovercraft. The design is that two propellers are pointed down, with a hole in the back of the craft. I believe this won't work but it has produced some very promising results in terms of how many penny roles it can hold. However, some of the time the craft spins in circles, and it also goes backwards. Why is this???

I have seen designs that have used two fans at the bottom that have worked. As for the spinning, I believe that the weight is not balanced or the airflow is not balanced. As for going backwards, I dont know how that happens, but I have seen it happen at competitions.

I'll second that. Our team uses a pretty standard system with 1 lift and 1 thrust fan. However, we have our design to a point where it can feasibly be run off of just the one lift fan. Airflow is fairly inconsistent, and the spinning makes it seem unreliable for competition.

Are we allowed to have 3 motors on the hovercraft but only two runnings/connected to a power source?