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-   -   How will FIRST measure muzzle velocity? (http://www.chiefdelphi.com/forums/showthread.php?t=41433)

ted bell 09-01-2006 14:32

How will FIRST measure muzzle velocity?
 
I was reading inthe rules that there was a max speed of the balls. I think its a great rule because everybody is on the same level when it comes to how fast a ball can travel. Rules are also great if you can police them, how does FIRST plan to police this rule, are they going to have six different radar guns to clock how fast the balls are going? I hope they have a simple way to inforce this rule or I see another "what is entanglemant?" debate we had a couple of years ago.

Kevin Sevcik 09-01-2006 14:38

Re: max ball speed
 
It's a safety and inspection kind of rule. You'll just have to satisfy the inspectors that your robot isn't going to throw balls faster than 12 m/s. That should be good for the whole competition unless you start throwing balls across the entire field or denting the plexiglass or something.

redbarron 09-01-2006 14:39

Re: max ball speed
 
Quote:

Originally Posted by ted bell
I was reading inthe rules that there was a max speed of the balls. I think its a great rule because everybody is on the same level when it comes to how fast a ball can travel. Rules are also great if you can police them, how does FIRST plan to police this rule, are they going to have six different radar guns to clock how fast the balls are going? I hope they have a simple way to inforce this rule or I see another "what is entanglemant?" debate we had a couple of years ago.


I think the inspection that the robot goes through before you can compete will probably include a speed test of your robots throwing speed. And if the judges or an official thinks that you changed your launcher they will make you test it again. thats the most logical thing i can think of since i dont think each ref will have a radar gun. :)

dhitchco 09-01-2006 14:51

Re: How will FIRST measure muzzle velocity?
 
If FIRST believes there will be an issue with exceeding the rule for "muzzle" velocity of a ball being airborne, it would be very easy for them to set-up a test of some kind at the SAME time & place that they'll be checking your robot for weight and size constraints.

Basically, a robot MUST get to mid-field or "closer" in order to NOT be in violation of the high-speed, long-toss rule. Maybe they'll set-up a test station across the top of the pits (wow.....)

Hopefully, with the official Poof-branded balls, it won;t be a big problem across the board, but wait and see during the build season who starts to "tout" their hypersonic ball tosser first......LOL :yikes:

KenWittlief 09-01-2006 15:25

Re: How will FIRST measure muzzle velocity?
 
knocking holes through the ceiling of the arena with a nerf ball would be a dead give-away :^)

or a switch on the operator interface for the launcher, with two settings:

STUN

KILL

Kevin Sevcik 09-01-2006 15:29

Re: How will FIRST measure muzzle velocity?
 
I fear any team that can get a ball to the ceiling at Reliant Arena. And if a team hits the ceiling in the Georgia Dome? That'd be quite a feat. (No fair smuggling a robot into the nosebleed seats.)

Scott358 09-01-2006 18:08

Re: How will FIRST measure muzzle velocity?
 
I don't know if they'll need to measure it, as they already know the max distance possible (which is for the "best" angle, which I believe to be around 30 degrees, at the max muzzle velocity they've specified).

So, if your scoring from further out than that, you've got a lot of explaining to do.

- Scott 358

KenWittlief 09-01-2006 18:18

Re: How will FIRST measure muzzle velocity?
 
Quote:

Originally Posted by Scott358
...So, if your scoring from further out than that, you've got a lot of explaining to do.

- Scott 358

tail wind?

positive spin (floater pitch)?

Human player telekinesis?

spacial disturbance in the time/space continuum?

dlavery 10-01-2006 08:21

Re: How will FIRST measure muzzle velocity?
 
Quote:

Originally Posted by KenWittlief
spacial disturbance in the time/space continuum?

Heh heh. Check out the special "black box" we will have on our robot. Just don't stand too close. We lose way too many rookie team members that way... :)

-dave

petek 10-01-2006 09:09

Re: max ball speed
 
Quote:

Originally Posted by redbarron
... since i dont think each ref will have a radar gun. :)

Yeah - only the head ref gets the radar gun!

MattB703 10-01-2006 09:32

Re: How will FIRST measure muzzle velocity?
 
Quote:

Originally Posted by Scott358
I don't know if they'll need to measure it, as they already know the max distance possible (which is for the "best" angle, which I believe to be around 30 degrees, at the max muzzle velocity they've specified).

So, if your scoring from further out than that, you've got a lot of explaining to do.

- Scott 358


Am I missing soemthing? The physics I remember says that the "best angle" is 45°. :confused:

KenWittlief 10-01-2006 09:44

Re: How will FIRST measure muzzle velocity?
 
45° gives you the farthest distance with no air (wind) resistance.

With something big and light (like a nerf ball) the best angle will be different (air resistance has a greater effect on the trajectory than gravity does).

Kevin Sevcik 10-01-2006 10:14

Re: How will FIRST measure muzzle velocity?
 
The "best angle" still appears to be near 45 degrees. I've made up a spreadsheet that roughly accounts for air resistance and I'm still getting the best range at around 43 degrees. Definitely not 30 degrees. However, my spreadsheet also doesn't think 35 feet is possible at 30 degrees, so make of that what you will. This is, of course, completely theoretical. We're going to cobble together a prototype in a day or two and see what that says.

Jon K. 10-01-2006 12:24

Re: How will FIRST measure muzzle velocity?
 
A quick prototype that we created had one of the balls going well over 40 feet at a speed of approx 24 mph, and that was measured with a radar gun that targeted the ball as soon as it left the muzzle.

meaubry 10-01-2006 12:34

Re: How will FIRST measure muzzle velocity?
 
I concur with Jon, we built a quicky prototype last night - but I didn't have gun to measure the speed.
My prototype was set at 30 degrees, after firing the ball it landed well beyond 35 feet, so I had to back off on the force being used in order to stay within the 12 m/s rule.

No doubt exceeding the 12 m/s can easily be accomplished - hand held radar guns could be used to measure with if available, other wise during inspection each team could be asked to set up at the 30 degree angle and shoot a ball to see if the travel is in excess of 35 feet.


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