The problem described in the original response is a common misconception. The throttle servo has a linear response to the the transmitter, but if you closely examine the throttle system on the carb, you will notice that it is NOT a linear system. The circular shape of the air opening is by its very nature a non-linear system. The size of the inlet path has a very large change, percentage wise, at the beginning, as the throttle arm is moved. As it approaches fully open, the percentage change is very small. I could probably do some higher math to actually model how it changes, but suffice it to say, that its non linear. Consequently, you get the behavior that the engine seems to hit max RPM before the throttle is fully open. There is actually a small change as it gets to full throttle, but its generally beyond the capability of the average homo sapien to distinguish without some experience.

I suppose it would be possible to program in a throttle curve using a computer radio and a tachometer such that there is a linear change in RPMs as the stick moves, but frankly I think its more trouble than its worth.

Fly more, worry less.

Brad