we are going to use two astroflight motor 603g (http://www.astroflight.com/sport610.html) for our counter rotating helicopter setup. the helicopter is just designed to fly, hover and land. no acrobatic moves.

the typical prop stated in the info sheet of the motor says 11x7. But there are only 14x5, 14x6, 14x8,10x4 and 10x8 in the list of props available.

Which prop would be the best substitute for the recommended prop? What will be the effect if we choose a bigger or a smaller prop for the motor?

thanks!