Quote:
Originally Posted by drkiraco
I did the math a little differently and got 7.2 inches for the radius. Probably a round-off difference between you and me. If anyone was seriously considering this, it would probably be better to make the fan bigger, thus it could run slower.
|
I was thinking about this some more, and I realized the original spec of 50N is a bit ridiculous. Sure it would make your robot fast, but once your fan spooled up, you wouldn't be able to stop (without cutting and reversing the fan, which would take a long time). 5-10N as a booster would be more reasonable.
I'd bet that 50N is more in the range of what an FRC robot gets on carpet, as it implies acceleration of nearly 1G for a max-weight robot. You'd have a 120lb rocket. (Edit: this is wrong. You'd have acceleration of 1m/s^2, which is nearly 10 times less than 1G. I need to go to bed).
I made an excel sheet to play with these numbers:
If you had a fan with a radius just wide enough to fit on the short length of your robot (35cm), you'd only need an output velocity of 3.1m/s for a 5 newton boost. It would only require 7.8 watts. For a 10N boost with the same fan, you need a 4.5m/s output. However, since a lot of that boost would get caught on the trailer (thus slowing you down), you'd need more.
Edit: But it occurs to me that a giant fan would pose an entanglement risk, and so probably isn't practical, if QA allows it at all.