For those who are skeptical about propellers - Team 2526

[MrForbes]

There's a rule about the wheels being perpendicular to the floor...I don't know about any rule saying they can't steer.

[Cyberphil]

ok, thank you. I was just a little confused.

[JGecko146]

Zrop,

It's not your design we're bashing. The design is really cool. It's that you seem to blow people off with a flippant comment every time someone mentions safety. Everyone wants to have a blast at FIRST but we also want to go home to our families intact. Therefore safety is huge. It especially concerns those of us who know things can go wrong even when you are being safe. That's why "trusting a robot" is a scary thing. I've been in and around FIRST for 13 years now and I still wouldn't "trust a robot" when it comes to my own personal safety. Just think about it.

[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

[Robert103]

Nice

[Cyberphil]

But how will they rotate quickly if they move with the steering of the wheels?

[Molten]

Originally Posted by zrop

Not if they quickly pivot 360 degrees ;D

Look up rotational inertia. It would seem the laws of physics do not agree with you on this stopping method. Good luck on trying to find a different way of stopping.

[Andy L]

Originally Posted by zrop

Not if they quickly pivot 360 degrees ;D

Rotational inertia. As said before the props aren't intended for anything more than spinning and moving an R/C plane. The vibration from the robot is already more forces than intended, let alone the sudden accelerations from crashes, and now rotational inertia. You should really start rethinking some of these issues. You're making it seem like this is all a joke and you're just shrugging off every suggestion. I think most people reading this thread have the same mindset that that's what you're doing with every single one of our posts.

[Woody1458]

Originally Posted by Andy L

Rotational inertia.

If you have no experience with this force (i didn't until last year) spin a wheel on a rod then try to rotate it like you would the props. You get very interesting results

[zrop]

Yeah I'm really concerned about the gyroscopical effects of the props. But hey, I've seen videos of hovercrafts using rotating prop bases, so i think it's feasable. We're going to figure out controlling this stuff this week, so we'll get back on the results. XD

[zrop]

Originally Posted by Andy L

Rotational inertia. As said before the props aren't intended for anything more than spinning and moving an R/C plane. The vibration from the robot is already more forces than intended, let alone the sudden accelerations from crashes, and now rotational inertia. You should really start rethinking some of these issues. You're making it seem like this is all a joke and you're just shrugging off every suggestion. I think most people reading this thread have the same mindset that that's what you're doing with every single one of our posts.

Alternatively, the motors could be thrown in reverse. The problem with that though is that the leading edge of the props would become on the wrong side, greatly decreasing thrust.

[Al Skierkiewicz]

Originally Posted by zrop

Alternatively, the motors could be thrown in reverse. The problem with that though is that the leading edge of the props would become on the wrong side, greatly decreasing thrust.

If you are using the Jaguar I would recommend you use the limit switch function to prevent a change in direction. If using a Victor, install a line in software to prevent counter rotation.

[David Brinza]

I hope you appreciate that the comments and concerns about the safety of your propellers is HELP from the CD community. I know several teams have given this approach serious consideration (including our team).

Team 980 chose an alternative drive concept, not because of safety concerns with fans, but for performance needs to support our game strategy. We felt we could contain a failed propeller and avoid having debris getting sucked in and becoming a dangerous projectile by using a "ducted fan" approach with steel mesh over the ends. I don't think your robot can detect a problem with your props and react fast enough to insure no shrapnel will be produced. It's better to have a design which is not going to allow anything dangerous to escape. With the ducted fan, you'll get better thrust performance as well.

I look forward to seeing videos of your robot on the move!