Hard drive motors or fans that are: included in any Kickoff Kit, distributed via FIRST Choice, part
of a legal motor controller (including manufacturer provided accessories), or part of a legal COTS
computing device
We recently bought a number of 40mm computer fans to mount on our Talon SR ESCs, but this rule caught my eye. Since we didn’t obtain the fans via a kickoff kit or via FIRST Choice, and they’re not the original fans or bought via the ESC vendor, and they’re not previously included in a COTS computing device, are they legal? We’re not using them strategically, just as replacements for Talon SR fans, and they’re not doing anything unexpected from a fan. Just regular 40mm fans.
I guess your fans don’t fall into any of those categories… thus making them illegal. ::rtm::
I can’t imagine your robot would not pass inspection because your cooling fans are third party tough.
That’s exactly what I thought. They would be technically illegal, but practically not. However, I’d still not like to rely on its practical legality, so I’m a bit over the fence on whether we should use them.
On the other hand, I see this as outside the intent of the rule. The rule is intended to be very specific. Only fans that are part of a KoP or FIRST Choice or sold specifically for an allowed motor controller are allowed, with the exception that a fan included on a COTS laptop (or other COTS computing device) does not render the COTS computing device illegal.
I definitely would not try to bypass the rules in anyways. If your RI would happen to “glance” at more than just the frame of the robot then you would still be in violation of the rules.
I read this rule to be that any Victor Fans (e.g. the model of fan that comes with a Victor 888) are legal regardless of whether they were acquired via purchasing a Victor or whether they are being USED ON THE ROBOT to cool a Victor.
I think if you started to take the impellers off and use the motors to do work beyond blowing air, we might have something to talk about but I think as it is as long as you are using the same model fan as any of the fans listed, you can use them in unlimited numbers.
This rule bothers me. DC powered “computer” fans are pretty ubiquitous, using a different brand/model isn’t going to give you a competitive advantage. On top of that, it’s borderline unenforceable. Does the GDC really expect all inspectors to have a list of every year’s KOP and try to match model numbers on every fan that shows up on a robot? :ahh:
Sorry for the rant, but it would make things so much easier if the rule were something along the lines of “DC powered computer fans of size X or smaller are legal”. Easier and cheaper for teams who need to cool a compressor/motor, and much easier for inspectors to enforce.
Having built a few computers in my day, I know that not all fans are created equal. There are some out there that get much more airflow than others, despite being the same size. So the rule does have some practical applicability.
That said, when inspecting the robot, I’m not going to be closely examining every fan that’s attached to a speed controller. If it looks like one of the fans that’s stacked up in my team’s electrical closet, then I’m going to assume it’s legal. If it’s a some blue one with built in LED’s, then I know it’s not legal (and yes, they sell ones like that, for people who want “cool” looking Computer cases!). If your using the fans to do something other than cooling on motor controllers, I’m going to take a closer look at them.
This is exactly my point. If an experienced LRI’s method of enforcement is " it looks like one of the fans that’s stacked up in my team’s electrical closet", what is an average inspector’s(aka me) method of enforcement supposed to be?
I completely understand, but my point is “Does it matter?”. Even a high powered 120mm computer fan doesn’t provide enough thrust to launch a boulder or deflect a frisbee. Are there safety concerns with using “some blue fan with LED’s”? Is using a high powered fan an unfair advantage to some teams? I’m just trying to understand why we have the restriction to KOP fans in the first place.
I’d say they aren’t legal. CTR doesn’t sell them, and they don’t meet any of the other criteria for legality. If they happen to have the same model number as the one Andymark sells as part of first choice, I’d pass them. Otherwise, I’d bring it to my LRI.
In general, I think the fan limitations were designed to keep the playing field level on power. If you had super awesome fans on your air compressor or speed controller, you could get more power through them, therefore giving a competitive advantage.
Yeah. As asinine as it is, the rules are the rules.
It would be nice for next year though, maybe at least have a size and/or airflow/current restriction. Some of the higher end (read, not for PCs or even workstations/servers) brushless fans run so fast that they’ll rip off fingertips ::ouch:: … and unless you had grilles or the fans actively controlled (to only be on in Auto/Teleop), which could also mandated in the rules, such fans wouldn’t be safe for robots that often get carried while booting up.
That said, the fans are still fine for off-season use… before the modern battery rules (which are like what I described above, only for batteries), there was only one (and later two) batteries one could use. Up to 2006 it was Exide (IIRC, I wasn’t in FIRST that far back), then 2007-2009 it was MK only, with Enersys batteries becoming the new KOP brand in 2010 as a second legal choice along side the MK units. What teams would do is use the “legal” batteries for competition and use those and other batteries of the same specifications for everything else. At least in my old team’s (1747) case, we had a local electronics supply for a sponsor and they carried PowerSonic batteries, of which an equivalent was available.
The same could be done with the fans, as the rules only apply at competition. In fact, if you have legal fans on talons already that aren’t going to see competition use (in an old/demo bot or the like), I’d swap them, which would save the cost of buying new legal fans. Sure they’d be used, but that way the fans wouldn’t be sitting without a use.
A rookie member and I had a similar discussion just this past weekend.
We came to the conclusion that big, important companies donate lots of gizmos and money to FIRST, and (partially) in return, they get to be the exclusive gizmo of FIRST Robotics.
Yes, the companies are donating their goods and services to a very good cause - they’re also very intelligently building a customer base for years to come.
Think of all the collegiate senior projects that use IFI or CTRE or PTC or NI products (for example) we’ve seen recently that may have otherwise used other components. This means FIRST students have been acclimated to prefer the FIRST suppliers’ products, which means that when these young ladies and gentlemen start their own companies, they’ll be predisposed to use FIRST suppliers’ products, which means the initial donations will have been very worthwhile.
Next time you listen to the radio or watch television, pay attention to the types of commercials played. Dollars to doughnuts, in a single break, you’ll only hear/see one commercial from any given type of local business (law firm, auto dealership, florist, etc.). Exclusivity is a huge negotiating tool.
Limiting the discussion just to Victor fans for the moment, the way I read the rules you don’t have to have these fans attached to a speed controller at all, they just have to have been attached to speed controller that was in a FRCKOP in some year (i.e. they have to be Victor Fans).
The really attractive thing about this rule (IF I AM CORRECT about not having to use them for their original purpose) is that they can be used in unlimited numbers and they can be powered directly via a 20A breaker per Table 4-2 in R48. That is, you don’t have to be able to turn them off when you are disabled. Turn on the main breaker and your fans go on.
The way I read this, you could make a hovercraft with hundreds of these guys if you wanted to as long as you powered them all via the 20A breaker.
Joe, until you run out of amps, and barring the other physics limitations of making hovercrafts that are FRC legal, I agree with your rule interpretation here.
Also, in terms of Q&A, Q844 is useful to this discussion.
Physics says no, since one fan (@ 12VDC) can’t lift its own weight, any number together won’t be able to lift their own weight, let alone the rest of the bot.
Rules wise, if you spliced it correctly and took care to avoid potential pinch points, it would probably be legal, although as propulsion devices, one might need to hook them to some sort of motor control (spike, victor, talon, etc.) to meet the intent of the rules (meaning the GDC would be likely to change the rules to bar such if one tried it).
A hovercraft doesn’t lift its weight using thrust from the fan(s). It creates a confined air cushion on which it floats. A vacuum cleaner can’t lift itself with the reaction force from its exhaust, but people regularly make hovercraft using them.
