Hovercraft

[cj.reeves]

is the coeficient of friction independent of surface area under the present conditions

[n_ambrogi013]

i think that someone already discussed earlier in this thread using a fan to generate downforce, effectively increasing the normal force on the wheels.

my question is, how would you calculate the amount of suction force that a fan can generate against a solid surface like the playing field? using drive motors to power a fan is really only worth it if there is a significant traction increase.

also, is it legal to generate downforce with a fan?

[scirobotics]

it is illigal to genarate downforce with a fan

[DonRotolo]

Originally Posted by Prontopwnage

hey you guys, your thinking to hard...
You could do the opposite and get more grip... Like that model car that can go on the ceiling! I don't know if that would work... What do you guys think?

I think you're not thinking hard enough, since you asked.

Originally Posted by cj.reeves

is the coeficient of friction independent of surface area under the present conditions

Yes, as coefficient of friction is a property of the interaction of two surfaces. But I think you want to know about pushing power, which theoretically remains the same because a larger area means a smaller force per unit area, but in reality a larger surface contact area means a very slightly increased pushing power.

Originally Posted by scirobotics

it is illigal to genarate downforce with a fan

Can you quote a rule please? Or is this speculation?

[Mike Betts]

Originally Posted by scirobotics

it is illigal to genarate downforce with a fan

Would you mind quoting the specific rule?

[OScubed]

It's pretty clear that anything that provides additional traction is ruled out by R06:

<R06>
ROBOTs must use ROVER WHEELS (as supplied in the 2009 Kit Of Parts and/or their equivalent as provided by the supplying vendor) to provide traction between the ROBOT and the ARENA. Any number of ROVER WHEELS may be used. The ROVER WHEELS must be used in a “normal” orientation (i.e. with the tread of the wheel in contact with the ground, with the axis of rotation parallel to the ground and penetrating the wheel hub). No other forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction) are permitted.
The surface tread of the ROVER WHEELS may not be modified except through normal wear-and-tear. Specifically, the addition of cleats, studs, carved treads, alterations to the wheel profile, high-traction surface treatments, adhesive coatings, abrasive materials, and/or other attachments are prohibited. The intent of this rule is that the ROVER WHEELS be used in as close to their “out of the box” condition as possible, to provide the intended low-friction dynamic performance during the game

Note the OR OTHER DEVICES INTENDED TO PROVIDE TRACTION.

[Woody1458]

If you wish to make a suction device tell me when you find a Unobtanium retailer because that would require something that both makes an airtight seal and has a µ=0

[EStokely]

Originally Posted by Woody1458

If you wish to make a suction device tell me when you find a Unobtanium retailer because that would require something that both makes an airtight seal and has a µ=0

Well lets not assume you need 100% effcientcy.

Any lowering of air pressure under the machine will provided additional Normal Force. So if you had skirts that are within 1/2 inch you would get a reduced pressure when you started vacuuming air out of the area.
Have I done the numbers? no...
Is there a prototype in the works? Yes.

It may not provided enough of a difference to use but I can't dismiss it out of hand.

I suspect a week before we decide yes or no on the idea.

[M. Gildner]

just a thought, but a hovercraft would provide a defensive advantage.
The fan could in theory push cells and rocks away from the trailer.

[Sean Raia]

I dont think that the fan in the back would be a good propeller on its own, but used with the wheels it may give a minor advantage.

[Tetraman]

This is a question that should be posed to FIRST, and I hope they vote in the affirmative that you can make a hovercraft.

And to pose the question as to if we can suction ourselves to the floor is another good question.

[Seat Ninja]

You could put free rolling wheels under the skirt so that on start-up, the skirt lifts the robot off the wheels. Also you could use several of those silver motors to power a centrifugal fan similar to this one. They are commonly used in commercial hovercraft and are more efficient at this task than a vacuum or a typical fan partially because it disperses the air evenly. Then use 2 cim's per fan for propulsion in a dual rear fan set-up.

Here's the type of fan I'm talking about.

[T3_1565]

Originally Posted by Tetraman

And to pose the question as to if we can suction ourselves to the floor is another good question.

The rules say somewhere (now with edit) that you cannot attach yourself to the arena surface.


<G29>
Arena Interaction –ROBOTS may push or react against any elements of the ARENA, provided there is no damage or disruption of the ARENA elements. With the exception of a ROBOT towing a TRAILER, ROBOTS may not grab, grasp, grapple, or attach to any ARENA structure

[scirobotics]

lol, i think it will be more like a game of air hockey

[excel2474]

I've built hovercrafts before and let me tell you that by time your robot is all said and done, you won't be able to hover. I mean, it could be possible, but that would require so much power that it's just not plausible. I just seriously doubt that you could build a hover craft and efficiently complete the mission.