This came up briefly in our teams design discussion. Do you think that there will be any significant air currents in the arenas that will alter the flight of a frisbee?
Air currents should have no if not minimal effect as long as you put sufficient spin on the disc. Ultimate players are able to throw a disc in 5-15 mph winds without having to compensate for wind. Slight air currents should be no problem.
However, if you throw the disc upside down, all bets are off. Or at least until someone tests this.
There would probably be the air coming from robots moving fast, and if the carpet is dark, (or any other color…black has more) there will be really small thermal updrafts. Otherwise, there won’t be any fans blowing. If you get a good spin on the Frisbee, that is all that is needed to keep in the air.
A defensive robot may use a fan to intentionally misdirect the frisbees. I don’t know how effective this would be, but I remember some bots used ducted fans in Lunacy.
From what i remember, the fans in lunacy were used to create more downforce as well as a lateral force to aid their speed around the low friction surface. I am not sure how this would translate to hindering another team and their ability to score
Point the fan up :eek:
No, the air in a large arena is fairly benign.
A lot of prototype shooters shoot consistently out doors.
If draft causes the operator to miss their first disk, they will adjust and the rest will be that much better.
Edit: Fans for the purpose of deflecting dosls will work excellently on the one point goal, decently on the two point goal, and very little on the three point goal.
We (1771) used two ducted fans on our lunacy bot. They provided about 10 extra pounds of thrust, laterally of course.
It was great, we could push anything around.
On the other hand, engaging the fans would drop our battery to about 6 or 7 volts. The battery would be shot every match.
Point being, I think for any robot to create airflow to deflect the fast moving Frisbees, it will be at a high battery cost.
After running our shooter prototype outdoors today I can say it had minimal impact on the left/right consistency (we were shooting in reasonably high winds) Our of the 8/10 shots I saw we were able to hit a vertical 2x4 with all of the shots from 30’. However, we did see quite a bit of up/down inconsistencies but we are working on identifying the cause of those.
The thought of defensively pointing fans up in the air occurred to us as well, and we did some testing with several large fans we had on hand in the shop. The results were pretty conclusive: even our massive 3 hp blower could not do any significant damage to the trajectory. The frisbee is simply in the air stream for too small of a time period.
Some other things we tried were angling the fan to blow towards and away from the frisbee, and neither had any more significant effect. All positions really lifted the frisbee several inches higher but it dropped right back down on the other side. We guessed something to do with the air stream was sucking it back down to where it started.
However- we didnt test upside down, as someone mentioned, nor did we duct the fan and test. We just quickly came to the conclusion that it wasnt worth the battery space and let the idea go.
I would love to see a system that works though!
Clearly this concept is why FIRST gave us 6 CIMs to put on the robot. Stick all 6 into a 6 CIM gearbox for a fan and use MiniCIMs for a drive. :rolleyes: I don’t think you’ll be able to blow a properly propelled frisbee off course unless you’re pinning the offensive robot. And at that point, just push them over.
Out of curiosity, how well would using compressed air blasts work to deflect them?
Considering you have only 1/8 NPT solenoids and a working pressure of 60PSI, (Rules R78 and 81, respectively), I’d hazard a guess to say rather poorly.
I’m sure you are right. It would be almost impossible to aim, time, and get the blast close enough anyway.
So what about using a vacuum to suck the Frisbee away, like a tractor beam…
One of my students brought up this idea over fans: Wham-O Air Blaster
Too bad they were made in the 60’s and are tough to come by these days.
We looked at Airzooka’s (sp?) for a bit but decided timing would be tough to pull off.
You can also make one of out a 5 gallon bucket and some plastic if you want more volume, the issue would be actuating it.
We did some brief tests with fans pointed up to see if it would deflect a frisbee. Our conclusion was that it was not a viable means of defense. The discs are pretty dense and are moving fairly quickly.
We did some tests with a leafblower and came to the conclusion that:
- The narrow beam makes defense with a leafblower impractical
- The leafblower may end up deflecting desks up into the goal making defense counterproductive
I bet 1551 could do it again