Turbulence
 

I was thinking... What if you make a robot that has a HUGE fan pointing up, then when you start, you just drive over to the platform right above the center goal and turn the fan on. With all the turbulence the balls will never make it in. But... you can't do anything but this, but that is assuming that the other team does center goal only... :p :yikes:

Re: Turbulence
 

Interesting, considering we have plenty of motors capable of powering an incredibly large fan to an incredibly high speed.

Re: Turbulence
 

shhhhhh.....don't tell anyone :p

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Don't worry.. It's ok. This idea is really a creative idea, but it can't do anything but defend the center assuming that all robots are for the center.. ;)

Re: Turbulence
 

How powerful would the fan be? If the shooter just aimed a little lower, the fan might blow the ball into the goal (assuming that their targeting isn't slaved to the camera). Still, it's a good idea, and the only (legal, reasonable, reliable) one I've heard this far for blocking a shooter.

Re: Turbulence
 

We talked about this, the best way would be to get a commercial leaf-blower and gut out the insides, replacing the motor and creating a compatibility gearbox.. you'd get something like 220 mph winds upward..

buts its not graciously professional. so we're not doing it..
if anyone wants to try it, I'm definately willing to lend a hand ..

Re: Turbulence
 

I don't see why it's not gracious professionalism. I mean maybe it's just my interpretation but I don't think that just because you exhibit gracious professionalism why you can't be super competitive, or take advantage of a field element.

In 2004 team KillerBees had a brilliant autonomous mode idea. They did a drive by on the autonomous balls that did a early release of all those balls they stored over the player stations. Their robot continued to the end of the Field and then as soon as manual mode started they sucked up your balls and carried them off, leaving you at a distinct disadvantage. It wasn't ungracious and it wasn't unprofessional, It was smart. I say if you see a niche that can be filled and gives you an advantage without violating the rules or stopping others from enjoying FIRST then go for it! It's actually not too different then parking your robot in front of the lower goals to prevent people from scoring. Try telling teams they can't block balls because it's not fair, your going to see a lot of it anyway and why not? It's smart and makes sense.

On a more technical view, I'm not sure how well it would work. One thing to consider is that the air will dissipate pretty quickly. I mean I can't remember seeing a leaf blower with more then 10 ft of range (though we do have stronger motors). Also leafs are pretty light, will it have enough force to move a ball? how about move a ball traveling at a high velocity? I recomend using more like a cannon in that you aim it slightly at a angle to slow the ball and displace the balls trajectory. I'm going to take a look at the inside of my leaf blower to see if it's gears could handle our motor's. :D

Re: Turbulence
 

Rephrase - whats what my team thinks. therefore we will not be doing that =p. I think it might be ever so slightly ungracious but eh, you're right, its not that big of an issue

I've already figgured out how to do this if you're interested.. you point it at a 75 degree angle, bot at the edge of the ramp. even if air dissapates, your barell should be exactly at 6 ft, you have only 2.5 ft to traverse... thats pretty $@#$@#$@#$@# easy with a 220 mph... now we'll assume ball is traveling at somewhere around 7 m/s towards the goal.
lets say you halve the flow-speed every meter.., (probably accurate) 98.34 m/s = 220 mph. now, we have a 2.5 ft gap or .762 meters..

so thats around 57 m/s air flow around the ball, this may or may not be significant.. now for the drag calculation...

we can use http://www.fluidmech.net/jscalc/cdre01.htm to calculate force

which is 6.24 newtons.. m =.18 kg , therefore a is 34m/s^2 !!!. This only increases as you go closer.... a 34 m/s^2 accleration is definatley nontrivial.

this makes a few assumptions ..
a). halving for every meter.. likely but could be optimistic
b). that you're only targeting the nozzle width, a wider nozzle would decrease v.
c). the key is how fast you can get the fluid (air) to go. If you can pump air at around 220 mph (commercial 7 amp leaf-blower) then you've blocked the goal for good.

a few problems
a). 220 mph is under small nozzle width, blocking a 1 m goal may not be best
b). motor may not be powerful enough compared to the beasts in leaf-blowers
c). 7 amps is alot.. you have 12 ampere-hours on that battery, yes you'll drain that sucker in less than an hour with nothing else running... that, is frightening.

Also I dont think you can even draw 7 amps (correct me if im wrong)

Re: Turbulence
 

I don't think finding a way to defend the center goals is un-Gracious Professionalismistic (wow).
Our team is considering options other than air, but I expect to see quite a few teams out there with methods of blocking it...
edit:forgot to answer the last post. Uh, yeah you can draw through either 20, 30, or 40 amp breakers.

Re: Turbulence
 

ya dude 7 amps isn't alot chill

Re: Turbulence
 

That's probably 7 amps at 120V or about 840 watts. You almost had me thinking this was a feasible idea...
Additionally, that may be a high acceleration, but a ball travelling at 10m/s passing through a .3m (1ft) blowing area will be in that region for 0.03 seconds.

Re: Turbulence
 

It's possible, even a low amount of turbulence can turn the curve of the ball into the wrong direction.. as long as it doesn't hit an audence member I think it might be legal... hmmm ... if the fan is facing the audience and you curve the ball from another robot into the audience. Would they blam you or the other team? because you never touched the other ball :p (jk, btw you don't want to hit any audience members.. bad rep= not good)

Re: Turbulence
 

After some informal testing yesterday, I can say that a leaf blower is very effective at deflecting balls from the center goal. However, taking a commercial back pack blower and adapting the available motors to supply the rpm's and power needed is most likely not do able with the First motors and power supply. Oh well back to the hunter, seeker, whacker defensive strategy.

Re: Turbulence
 

Why not suck instead of blow? With some sort of motor running a fan (not that hard to make, weld a couple bits of sheet metal to a collar) you could suck them into a hopper. Sure the range might suck (well maybe not, last year's fisher price at 24000 rpm could probably pull a good amount of air) and you'd need mesh over everything to keep from chewing up stuff. Speaking of which, you'd need to watch wiring and tubing to make sure the suck/blow force of the fan doesn't unplug it. (not really an issue with tubing, but those pwms are screwed.)

Re: Turbulence
 

Errr... sucking would require much, much, more energy.

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if so.. think more Normal force..... =..... unpushable robot? :D
actually i think its impossible to get a 220mph air current...... i dont see how you got that number.

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Has anyone tested using a leaf blower to launch the balls? Most people report the balls as being just under 7" so you could feasibly use 7" ductwork as a cannon. Creating a sealed system might be a little more tricky.

As far as feasibility, I don't think you'll get 200mph, but it seems that if you attach a globe motor to a blower you'd get a pretty good amount of air. Maybe the results would be similar to this blower:
http://www.makitatools.com/menu.php?...et&tag=UB181DZ

If anyone could dig up a spec sheet on the motor in this blower we could compare it to the kit motors.

Re: Turbulence
 

how does using suction take up an more power than blowing???????? the air that comes out of the blowing end had to come from some where! so if it shoots out of a collar at 220 mph, if u switched the direction of the rotation of the fan than it should suck at the same speed.

Re: Turbulence
 

I assume with sucking you'd want to grab the ball for yourself. With blowing you only wanted to knock it off course. The robot hopper is a much more specific location than "anywhere but the goal". And even if you could pull the ball into your robot you need even more power, or less simple design, to keep it there. i can just imagine the ball bouncing off and going into the goal anyway :)

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220 mph is the leaf-blower I own.. thats where I got that number.. I think if you use 2 of the big CIMs, and create a gearbox, that number might be feasible .. but of course I suspect this will drain the battery faster than any other design.

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You know how pneumatic wrenchs work? why not do that? get the pressure from the pneumatic tank and input it to a mini fan that extends out to larger propellers.

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I thought of another benefit of sucking. If you blow then your column of air will invariably point towards the goal, unless you're off to the side. So, if a team gets a ball in the column they score and you look stupid. So, maybe this should be an offensive strategy.

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I don't think sucking air would be nearly as efficient as propelling it. When air get pushed out it looks like a mushroom (I know not exactly but thats as close as i can describe). When sucking air however, air from all around will rush to fill the vacuum. Hardly something you can aim, think how powerful vacuums are but how short their range is.

Re: Turbulence
 

The concept used to explain what you're talking about is "entrainment". Blowing air will drag more air along with it, moving a lot more than just what the fan is capable of. Sucking air doesn't get the same benefit.