RE: Futaba 9C Radio
Dave,
I think "S" stands for synthetized. This is so with the 9Z: there is the 9ZAP and 9ZHP. Then the 9ZAPS and 9ZHPS that are the synt. ones.
Regarding the difference between airplane and hely, it is not so much. Both have all programs (airplane, hely and glider), the differences are:
1) A version has snap roll (spring type) switch, while hely has not.
2) A version has ratchet on throttle stick, while hely has not (i.e. the stick is without springs and it stays where you put it)