I am looking for atwood specs for this years atwood motors. i have seen alot from previous years and i need to know for sure that this years will be the exact same. as well i am unsure of what speed to use to do my calculations. i have found out that for out robot to go 5 feet /sec with a 6inch wheel i need to gear down the motor 28:1. can someone complete this calculation for me to make sure i am correct. thank you
dan the man
Check the Guidlines_C.pdf document (Guidelines, tips, and tricks). Strangely this year is lists the free speed a little less and the torque in oz-in instead of Nm. I have not converted it though.
I dont currently have the specs but i will give you some aproximations
well under a regular load the CIM does just under 5000 (something lke 4960) rpms SO:
5000rpms /60 seconds is 83.33 rps which is 41.6 FPS with 6" circumferance whells without a tansmission.
so you equation would be 41.6fps * (gear ratio) = 5fps
that gear ration would be apx 1:8 giving you a speed of 5.2 fps under a normal load remember you need to consider load and amperage when designing a transmission theese atwoods have the potential to draw much much more than the 40amps you are allowed.
(The above is all using the 5000rpm aproximation)
For info on this i suggest you read through :
http://lancet.mit.edu/motors/
it is listed in the FRC manual on page 4 of the robot chapter.
Just as a side note i learned this lesson the hard way last year when we drew 90 amps in a stall and continually popped breakers. Its not fun at all. 
Small loss of Pi, figures are correct for a wheel with as you say a 6" circumference, that would be 6/3.14 to get diameter, A 6" wheel is 6*3.14.
So 83.33 *1.57’ gets 130.8 fps plug that in:
130.8 * (gear ratio) = 5fps and you get 26:1
-Biff