Ultimate Defense: The Fan Bot

So my team had an idea for the ultimate defense bot of this year… what if you had a 2 motor drive, 8 motor fan mechanism (to be explained) and pneumatic brakes. In auton this robot would drive straight towards the opposing teams net and park right at the bar. Then it would fire pneumatic brakes into the ground (as many teams have designs for included ourselves). As soon as user control started, it would start up a fan made out of reinforced Plexiglas, that is geared insanely high and uses eight motors. That way when balls are launched over the net, the fan blows them off course and away from the net. Anyone think this is practical? :smiley: or have any similar crazy ideas? We are really tempted to build a prototype, but don’t know if we can get the needed amount of force to push up a column of air strong enough to throw the ball off course!

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I love this idea, but I think the balls are moving too fast and too heavy to be blown off course by a fan made from 8 motors and VEX parts that is multiple feet away.

that’s what i was afraid of, i didn’t think the force of the fan could overcome the velocity of a ball launching towards the goal… maybe ill try it anyway, and if it doesn’t work at least people will enjoy my remote control fan on wheels on the hot summer days of VEX :wink:

after doing some calculations with air resistance, over the course of the balls entire flight, the difference between caclulations that include air resistance and the ones that don’t are not that great. there for, the affects of air resistance over the flight of the ball are somewhat negligible, based on this I don’t think that the air over 2 or so feet of flight will do anything to the ball

My kids talked about that this summer and they even played with a leaf blower to get an idea of what it might take to make this happen. I think it all started when somebody on the forum said that a wallbot would be impossible this year. They called it the jillnado for reasons that aren’t clear to me. They tried throwing balls through the leaf blower current to see what would happen, but I don’t remember what kind of conclusions they came to - if any. As a rough estimate, maybe look at what the power requirements are for an electric leaf blower and see how that might compare to what the Vex motors can provide. I think the 393 motors are good for about 4 watts of power. It would be really funny if somebody can get it to work, even for just 20 or 30 seconds.

I had an idea like this too :P, let me see if I still have the sketches I made…

I found them :smiley:

This is what I do when I get really bored :stuck_out_tongue:

With a 1000:1 gear ratio as shown in your sketch and turbo motors, that would be 240,000 RPM!!! my launcher is estimated at 3,500 RPM… i feel bad for the poor soul who sticks his finger in THAT gearbox!

ya… I may want to rethink that.

A 1000:1 gear ratio seems a bit unrealistic, I don’t think that 8 motors would be able to power that.

Is a 1000:1 gear ratio even physically possible? I believe you can get 1029:1.

7:1 x 7:1 x 7:1 x 3:1 = 1029:1

That’s why I drew 10 motors. Although the extra 2 motors probably wouldn’t do much…

and yes, it was 1029:1 that I was referring to, I was just to lazy to find the exact number :stuck_out_tongue:

Although 5:1 x 5:1 x 5:1 x 4:1 x 2:1 would be 1000:1 (the 4:1 and 2:1 being sprockets)

We need someone to figure out the torque something and speed something to see if this is even physically possible :stuck_out_tongue:

That would be so cool thou, #1000:1FlywheelMasterRace :smiley:

Any chance of employing a centrifugal fan concept? I’m wondering if you can whip the air around so fast that the pressure gets high enough to liquify the air and shoot it out in a jet. Any thermo kids out there know if that’s possible? (how can I post a smiley here???)

I had this crazy idea early on in the season as well, but I never explored it. Another thing that would be absolutely crazy would be if someone built a hovercraft. I don’t know if this is possible with VEX parts, but if it is, that would be crazy to see in a competition, because it would probably lie within a lot of gray areas in the rules.

This is something we have been dying to try, just haven’t found the time. Funny how many teams brainstormed something similar! My thoughts are that a small radial fan like a leaf blower has to run at really high speeds to generate enough airflow. Maybe a large squirrel cage like a furnace blower running at lower speed? Balance would be critical… Either way, if anyone builds one I want to see pictures!


Speaking of hovercrafts… Can’t wait to see this thing completed… They got stuck at the fiberglass steps and needed some professional help from Sikorsky (now Lockheed Martin).


I’ll look forward to seeing it! Now that I think of it, a flying robot design could also be referred to as a drone or helicopter, depending on how you build it.