i guess i should have been a bit more clear, you CAN use 27 MHz in the air, the FCC and AMA wouldnt hold it aginst you if you did BUT your plane sure would if it's anything much bigger then a park flier because of the limited range unless you wanted to string along a few yards of antenna dangeling out the back of it.
ORIGINAL: CGRetired
That's not exactly true. What is true is that a receiver will receive if it's on the correct frequency AND if the antenna is intact. Shorten the antenna and you have reduced the capability of the receiver to properly receiver the transmit signal.. no matter HOW powerful the transmitter is. It relys on wavelength to receive the correct frequency. Wavelength is specific to the operating frequency and must be very close to that length, if not spot on, to operate properly. The closer it is to the proper wavelength the better the receiver will perform, range wise.
the range is again dependent on the transmitted signal and TX antenna height (can be substitute for RX height in plane/heli flying), regardless of how far off tune the RX antenna is in relationship to it's receiving frequency. the reasoning for range reduction with off tuning is because the off tune is reducing the signal strength into the receiver. in most model applications we use a 1/4 wave antenna (39 inches in 72 MHz systems) and increasing that to a a half wave would increase range by about 1.5x but who wants that much antenna dangling out the back of our planes????
kc