Re: pic: Compressor Backpack
 

This might help you.

If you have a large air tank off the robot and use the robot compressor to fill it the morning of the competition, you could then use air from this tank to pre-fill your onboard tanks before each match. This would still meet the requirement that all air comes from the one compressor and allow you to hit a higher psi before starting your compressor to finish filling the tanks.

I do not believe there is a rule stating that air cannot be temporarily stored off the robot.

Re: pic: Compressor Backpack
 

ONE Vent Plug venting ALL stored pressure, even off board pressure.

Now, if you use Quantum Entanglement to activate a vent on the off board tank, I wonder if that would violate the no other wireless communication rule.

Re: pic: Compressor Backpack
 

R74 and R75 provide (only) two methods of using an off board compressor, illustrated in Fig. 4-8 and Fig. 4-9. Neither of these permissible methods includes off board air storage.

Re: pic: Compressor Backpack
 

R70:
Emphasis mine.

Honestly, this backpack scares me from a safety perspective. What happens to the unlucky person wearing it if a tank should explode? As an LRI, I would insist it be removed from the venue, and I bet the UL Safety advisors would agree.

Re: pic: Compressor Backpack
 

This. This times all of it. As a participant at an event I would want that removed. Plastic air tanks scare the bejesus out of me, mostly because I know first-hand how much energy and how much shrapnel they make.

If the pack got dropped while it was pressurized really bad things could happen. Please do not use this device, ever. I know it seems cool, but it's just asking for a disaster.

Re: pic: Compressor Backpack
 

It's really, really cool in concept. Pretty much anything turned into a backpack is pretty awesome, and you've obviously made something that serves a very good purpose. I agree, though, about the safety problem. Nobody can stop you from using it in your shop, but i'd suggest using metal air tanks for something like this.

Re: pic: Compressor Backpack
 

I agree with Jon.

At LRI training at HQ in early Jan, one of our fellow CMP LRI who works at an Army Testing Lab hired an intern to test the most common plastic tanks available to FIRST teams. The results for the black Clippard tanks was good. The white Clippard tanks (See the Manual for the exact p/n) were ruled illegal after several failures during the season and the resultant testing this summer at the Army Lab. And if I remember right, the performance deteriorated when damaged, nicked or abused, even slightly.

Kudos for thinking outside the box, but you won't see one being used on my team or at my event. Period. End of story.

Re: pic: Compressor Backpack
 

You beat me to it Jon. Those white tanks fail regularly if even slightly nicked or damaged. I saw one go off last year on the field and it sounded like a grenade going off. The plastic shards from an exploded tank would be a hazard not only to the wearer but those around him.

That looks super dangerous.

Re: pic: Compressor Backpack
 

I was just thinking about this last night, and we should at least encase the entire pack in a sheet of some thick polycarbonate, or some other method of keeping everything inside the pack in the event of any catastrophic failure. We should also replace the tanks with their metal equivalents.

I did mention that this pack is unfinished, and still requires some more safety features. We just needed something built to use for practice, and plastic tanks are what we had on hand.

If this is ever used, it is easily depressurizable for wearer movement to help reduce any accidents. This is only intended for use in safety glass areas around the robot when the robot is running and only when it is needed.

Having a member of our team walking around an event with a pressurized pneumatic backpack is just plain idiotic, and is not our intent with this system.

We don't intend to keep it pressurized for any extended length of time; only when we need to repressurize the robot for practice or testing.

Perhaps a tankless backpack may be the best option for safety, so pressurized air does not get stored in the pack at all.

If we deem this pack too unsafe still, we will make sure to keep it out of an event. Thank you all for your concern. I'm also all about safety, and I want to do my best to help make this pack safer for my team members and every volunteer, student, mentor, and attendee at an event, if that's possible. :D

Re: pic: Compressor Backpack
 

It's a great out of the box idea, so you should feel great about that.

I think you got great rules feedback, with some redesign and some Q&A responses you'll have a working system. Metal tanks, shroud, etc are the first steps.

Remember, they laughed at Einstein, and now he has a field named after him.

You can always display it as a "future project" at events. Without air it's not a safety problem

Re: pic: Compressor Backpack
 

Re: pic: Compressor Backpack
 

If you he seen the videos Dana, myself, and the rest of the LRI's saw at training, you probably wouldn't think some lexan would be enough. When these things go off, there is a huge amount or force and speed behind them.

I also want to add that directly connecting it to a battery, as it appears in the picture, is extremely dangerous and could very easily lead to an over-pressurization situation. That's why the rules clearly state the compressor has to be controlled by the robot.

Re: pic: Compressor Backpack
 

Team 1746 built a back pack tshirt cannon during the off season for publicity at our school's sporting events (and mostly because I was bored for a few days in class). It's a little heavy and cumbersome but it can fire 6-8 shots per arm and has adjustable pressure for football stadiums vs basketball courts. Everyone at our school loved it and it was really fun to build; i'll try to post a picture of it if I ever get time :rolleyes:

Re: pic: Compressor Backpack
 

Again, I have to say that this compressor pack is unfinished and will have a pressure switch and relay. The tanks are being replaced with metal ones. We can opt for a carbon fiber shell if that would be effective, or get rid of tanks altogether. My thought wasn't just "some lexan" but a sheet .25 inches thick, which I think would be enough for high impact, but I'd have to see the videos that you mentioned to really get an idea. My objective at this point isn't necessarily to try to get it "safe enough" for an event, but get it "safe enough" for personal shop use.

I'm open to more suggestions to make this safer for non-event use, since the chances of using this at an event are low, and out of courtesy, it's best to keep it out of the pits and arena at all times.

Re: pic: Compressor Backpack
 

Our team made one of these off-board compressor/air pack deals a few years ago. We used a 5 gal. steel tank rated for 250psi and then a FRC legal compressor. We considered all rules and believed it to be legal. We had pressure blow-off's and dump valves on both robot and pack. Big Al promptly ruled it unsafe for numerous reasons.

In retrospect, it was an unsafe idea even though the system worked well at the time and we had built in extra safeties.
Sacrificing safety just to save some time is not the best practice.