View Single Post
  #116   Spotlight this post!  
Unread 05-02-2009, 22:11
Daniel_LaFleur's Avatar
Daniel_LaFleur Daniel_LaFleur is offline
Mad Scientist
AKA: Me
FRC #2040 (DERT)
Team Role: Engineer
 
Join Date: Apr 2005
Rookie Year: 2003
Location: Peoria, IL
Posts: 1,967
Daniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond reputeDaniel_LaFleur has a reputation beyond repute
Send a message via MSN to Daniel_LaFleur
Re: For those who are skeptical about propellers - Team 2526

Quote:
Originally Posted by zrop View Post
I'm pretty sure that if the props can resist any vibrations that they and the motors generate, they should hold in a robot collision. I mean yeah, it will be a significant change in acceleration, but that's still no reason for the props to spontaneously explode.

Oh and update: We've decided to add power to the back 2 wheels powered by a CIM motor. So basically, that'll add some extra acceleration that we lack, and the props should handle well with the turning. ;D
Why is it that I shudder every time I hear "I'm pretty sure" when they are talking about engineering?

I'm not too concerned about the vibrations of the motors. I'm far more concerned with the shock of impact from another robot.

**Gets up on soapbox**
Why not be "sure" rather than "pretty sure" by running the bending calculations. I am "pretty sure" that your robot will see a better than 10G impact with another robot or the wall (this will be transmitted throughout the robot and anything cantilevered will feel the full force across its beam.). Calculate that force across the beam of your prop and use the weight of your prop divided by the number of blades. Personally I'd use 20G as a safety margin. If the material does not bend further than where it will permanantly deform then I'd call it fairly safe for the forces it will see ... then you need to protect it from outside forces like other robots and orbit balls.

Props can be very effective. Lets just make sure they're safe as well.
**Gets off soapbox**
__________________
___________________
"We are not now that strength which in old days moved earth and heaven; that which we are, we are;
One equal temper of heroic hearts, Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield. "
- Tennyson, Ulysses