Quote:
Originally Posted by Rick TYler
Gordon Murray's Brabham was copying Jim Hall's Chapparal 2J from 1970: http://www.photoessayist.com/canam/c.../chaparral.htm. It was a Can-Am racer that used a 45hp snowmobile engine to drive two ducted fans producing 1,000 pounds of static down force. If someone can move enough air with the limited power available I don't know why this wouldn't work for a FIRST robot. In some respects FRC robots have advantages over the "sucker" racers -- a perfectly flat "road" surface and no suspensions. I don't know how to do the math (sorry, Mark) on an aerodynamics problem like this, but a pair of CIMs driving 8-12" fans mounted vertically in cylinders open on the ends might generate some significant normal force. I wouldn't think it would approach 1,000 pounds, though.
EDITED: Here's a link to a Website of a model-builder who constructs battery-powered hovercraft: http://www.model-hovercraft.com/index.html. A hovercraft is only a Lunacy robot turned upside down.
Or... how about an electric hover-lawn mower? http://www.flymo.co.uk/node3126.aspx |
With some help from a few mentors from my old team I did the math. Based on the horsepower output of a Cim motor your could use a fan that moves roughly 1000 cubic feet per minute. Two of those on the robot so 2000 cubic feet per minute. If you use the entire bottom surface of the robot leaving a 1/8" gap with the floor that is capable of generating a negative pressure of .72 psi multiplied across the area of the robot 1064 square inches that is approximately 766 additional pounds of down force. Added to the weight of the robot that is 886 pounds total downward force. I completely understand Bill's concern, but darn if it wouldn't be awesome to see.
The fan source I was considering is Cincinnati Fan Company.