Legality of third party fans

[Sparky3D]

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?

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.

[Jon Stratis]

Originally Posted by Sparky3D

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?

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.

[Sparky3D]

Originally Posted by Jon Stratis

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.

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?

Originally Posted by Jon Stratis

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.

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.

[engunneer]

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.

[Rosiebotboss]

Originally Posted by Sparky3D

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.

The important point here is this: "Does it matter?" Probably not.

Is it legal? No.

Your call. Do you want to potentially miss a match?

[ratdude747]

Originally Posted by Rosiebotboss

The important point here is this: "Does it matter?" Probably not.

Is it legal? No.

Your call. Do you want to potentially miss a match?

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 ... 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.

[SamM]

We're having trouble finding info on fans from previous KOPs.

Does anyone have a manufacturer/model number list of what was given in previous KOPs?

Were 80mm fans given in any of them?

Thanks!

[Taylor]

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.

[Joe Johnson]

Originally Posted by Jon Stratis

<snip>
That said, when inspecting the robot, I'm not going to be closely examining every fan that's attached to a speed controller.
<snip>

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 FRC KOP 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.

Am I wrong?

Dr. Joe J.

[engunneer]

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.

[ratdude747]

Originally Posted by Joe Johnson

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 FRC KOP 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.

Am I wrong?

Dr. Joe J.

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).

(I know you were probably joking...)

[Alan Anderson]

Originally Posted by Joe Johnson

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.

Originally Posted by ratdude747

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.

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.

[ratdude747]

Originally Posted by Alan Anderson

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.

Yes, but the issue still stands. Even with a proper skirt, I don't think these fans could generate enough air pressure to sustain a cushion under their own weight. All they are meant to do is provide some cooling breeze... the fan shrouds are too loose and the motors too wimpy. Vacuum cleaners are meant to flow a lot more air; they're more or less hovercrafts in reverse. Hence why they can be made into hovercrafts.

[Joe Johnson]

Originally Posted by ratdude747

Yes, but the issue still stands. Even with a proper skirt, I don't think these fans could generate enough air pressure to sustain a cushion under their own weight. All they are meant to do is provide some cooling breeze... the fan shrouds are too loose and the motors too wimpy. Vacuum cleaners are meant to flow a lot more air; they're more or less hovercrafts in reverse. Hence why they can be made into hovercrafts.

So maybe you have to put these fans in series to get enough pressure to provide the air cushion you'd need to be a hovercraft... ...at some point someone is going to say, "challenge accepted" and actually try to build this thing just because...

...don't make me do this...

Dr. Joe J.

[Jon Stratis]

Originally Posted by Joe Johnson

So maybe you have to put these fans in series to get enough pressure to provide the air cushion you'd need to be a hovercraft... ...at some point someone is going to say, "challenge accepted" and actually try to build this thing just because...

...don't make me do this...

Dr. Joe J.

That would be a good way to clean out the parts closets for a hundred teams or so! And if you build it, maybe you can get your local MC to ride it around during competition!