For those who are skeptical about propellers - Team 2526

[Andy L]

Originally Posted by JVN

"plastic meets the road"

fixed.

I'm curious on your reasoning also, the main reason I dismissed propellers was not only safety, but slowing and stopping. How well does it stop and change direction to reverse?

[zrop]

Originally Posted by Andy L

fixed.

I'm curious on your reasoning also, the main reason I dismissed propellers was not only safety, but slowing and stopping. How well does it stop and change direction to reverse?

Theoretically, we're supposed to be getting 30-some newtons of thrust from the current arrangement... and with the calculations (which i long forgot) it was supposed to be able to accelerate faster than bots that use standard wheel drive. However, I emphasize that this is not the final arrangement -- we should have standard triblade props delivered this monday with a pitch of 4, and furthermore, if we get more thrust out of that, we'll try to custom order triblabe or quadblade props with a pitch between 1 - 2, idealizing our max speed (at around 7-15 mph) while boosting rpms and increasing power. THEN, with the addition of a duct (ideally, increasing power by an addition 5%) we should be operating at pear conditions.

Also, the idea of hybridizing our bot has came up: i.e. powering the back two wheels for extra acceleration. Although that's a ton of power stress on the battery, the 3rd CIM for the powered wheels would only work during acceleration, so we should be alright. =)

[Molten]

Ok, My thought: I know this is probably asking alot...But could the regionals have walls along the perimeter to protect the crowd? I don't mean to be overly cautious, but I think I'd feel a little uncomfortable sitting in the crowd while some of the possible bots are going to be running. I'm not asking for anything too fancy. Perhaps just a wall like there is between the drivers and the field. I know, props could easily go over this, but at least it would cut out the worst case scenario.

Otherwise, a cool design. Good luck with the competition. And I hope nobody gets hurt.

[Cory]

Originally Posted by Molten

Ok, My thought: I know this is probably asking alot...But could the regionals have walls along the perimeter to protect the crowd? I don't mean to be overly cautious, but I think I'd feel a little uncomfortable sitting in the crowd while some of the possible bots are going to be running. I'm not asking for anything too fancy. Perhaps just a wall like there is between the drivers and the field. I know, props could easily go over this, but at least it would cut out the worst case scenario.

Otherwise, a cool design. Good luck with the competition. And I hope nobody gets hurt.

Or FIRST could just solve the problem directly and not allow unsafe robots to compete

$0.02

[Molten]

Originally Posted by Cory

Or FIRST could just solve the problem directly and not allow unsafe robots to compete

$0.02

Only thing. Just because FIRST says it safe, is everyone going to make the same ruling? For instance: We've all seen those "smart" cars. They are ruled to be safe. However, I will never drive one. I just wouldn't feel safe, regardless of whether or not I am. You have to remember when it comes to safety, apparent safety is close to the same importance of actual safety.

[Al Skierkiewicz]

Time for my two cents...
I am a lead inspector, and yes I am concerned about the safety of anyone at any time. This includes participants, volunteers, camera people (many of whom I know), judges and refs. If that makes me a Safety Nazi then I can live with that label. I am concerned about safety when your robot is in your pit, on the practice field, on the competition field or anywhere in between. Pits are crowded places in which I spend a lot of time and I have seen things over the years that curdle my blood. First is about innovation and creativity in design and we should encourage those ideals for the betterment of the program, but not at the loss of other equally important ideals such as safety. We have low voltage power sources for your safety, electrical rules for your safety and pneumatic rules for your safety. Expect inspectors to take a close look at your designs not only for safety but I would be prepared to show accoustic output as well. Should the GDC issue guidelines for prop driven robots we will follow those guides explicitly. Until then good luck with your development.

Originally Posted by Molten

Ok, My thought: I know this is probably asking alot...But could the regionals have walls along the perimeter to protect the crowd? I don't mean to be overly cautious, but I think I'd feel a little uncomfortable sitting in the crowd while some of the possible bots are going to be running. I'm not asking for anything too fancy. Perhaps just a wall like there is between the drivers and the field. I know, props could easily go over this, but at least it would cut out the worst case scenario.

Otherwise, a cool design. Good luck with the competition. And I hope nobody gets hurt.

Should be fine. If you'll be at the Portland regional, I'll have a Kevlar helmet you can borrow, as well as glasses capable of withstanding a shotgun's deerslug at 5m. (Yay ROTC!)

I honestly don't want to see FIRST turn into battlebots, where the field is contained by walls. It blocks viability, and makes the competitions ugly and slow due to access.

[zrop]

Originally Posted by CraigHickman

Should be fine. If you'll be at the Portland regional, I'll have a Kevlar helmet you can borrow, as well as glasses capable of withstanding a shotgun's deerslug at 5m. (Yay ROTC!)

I honestly don't want to see FIRST turn into battlebots, where the field is contained by walls. It blocks viability, and makes the competitions ugly and slow due to access.

I really think you guys believe that props are bound to spontaneous explode or something. As long as balls or anything of a significant mass does not touch them, there is no reason for them to catastophically fail. We'll most likely be replacing props after every round / two rounds, just to rule out any failure chances due to wear. Beside that, I believe any other precautions are just silly. I mean, I trust the machine... I stand a foot away from it while it's on. Idk if others trust my contruction, but i sure know i do.

[Vikesrock]

Originally Posted by zrop

I mean, I trust the machine... I stand a foot away from it while it's on. Idk if others trust my contruction, but i sure know i do.

Our robots have never had props on them and I'm always more than a foot away from them while they are on unless they are propped up on blocks.

I can't say I understand why your blatant disregard for the safety advice posted by members with experience with these systems means that I should trust your robot to be safe.

If this robot manages to pass inspection with the safety cage shown in those pictures, I will be instructing my team to at the very least put on safety glasses in the stands every time your robot is on the field.

[zrop]

Originally Posted by Vikesrock

Our robots have never had props on them and I'm always more than a foot away from them while they are on unless they are propped up on blocks.

I can't say I understand why your blatant disregard for the safety advice posted by members with experience with these systems means that I should trust your robot to be safe.

If this robot manages to pass inspection with the safety cage shown in those pictures, I will be instructing my team to at the very least put on safety glasses in the stands every time your robot is on the field.

I'm not blatantly disregarding, I'm taking them into consideration and adding just enough safety features so that the props can still function.
We will upgrade the cage, in particularly in the 'plane of destruction'.

And really, say a prop was coming at you, I wouldn't be that concerned about my eyes, but rather, other parts of my body. Becuase theoretically (depending the mass of the fragment ofcourse), you'd get some penetration in the skin if that hit you. And then... surgeons would have fun dislodging a 'plastic knife' from your body. Not really the best image, but.. atleast you'd be able to see your own masacre. [sorry for the sarcasm, I'm just a little angry about our progress XD]

[Wayne Doenges]

Have you ever been to a competition? After each match you will see various parts from the robots on the floor. What if a bolt or nut was to be flipped into your props.Even if they didn't damage your props where does the part go after hitting the props.
Also, on a safety note. In your videos it shows your robot going along the floor PAST all the students with uncage props. When I'm around running R/C aircraft I NEVER put myself in the plane of rotation. I've seen first hand what a prop can do if it breaks and flies free. I've seen them imbed themselves into 2x4 park benches.
PLEASE BE SAFE!!!!!

[zrop]

Originally Posted by Wayne Doenges

Have you ever been to a competition? After each match you will see various parts from the robots on the floor. What if a bolt or nut was to be flipped into your props.Even if they didn't damage your props where does the part go after hitting the props.
Also, on a safety note. In your videos it shows your robot going along the floor PAST all the students with uncage props. When I'm around running R/C aircraft I NEVER put myself in the plane of rotation. I've seen first hand what a prop can do if it breaks and flies free. I've seen them imbed themselves into 2x4 park benches.
PLEASE BE SAFE!!!!!

Yes. Debris would be an interesting encounter. I'm thinking of loosing the set screws on the gears just at the point of slipping. Then if there is any added resistance [ideally] the prop would simply slip through and maximum damage could be eliminated.

[Woodworker88]

Originally Posted by Wayne Doenges

Have you ever been to a competition? After each match you will see various parts from the robots on the floor. What if a bolt or nut was to be flipped into your props.Even if they didn't damage your props where does the part go after hitting the props.

On military aircraft carriers, twice a day or more all members of the crew stop all operations to perform a FOD (Foreign Object Disposal) walk, in which they walk shoulder to shoulder across the flight deck looking for any foreign object as small as 1/8" in diameter. This is to prevent the disasterous consequences that could result if one of these objects were sucked into a jet intake or blown around by jet exhaust or prop wash. Keep this in mind as you work on your systems.

[Robert103]

I think this is a good idea, but i have one question, won't using propellers make stopping harder?

[zrop]

Originally Posted by Robert103

I think this is a good idea, but i have one question, won't using propellers make stopping harder?

Not if they quickly pivot 360 degrees ;D