If the radio uses 27 Mhz and the antenna is too short, make it longer. How long? Whatever you can manage without doubling the wire back onto it's self. The 'bestest' way is to make it stand up straight, out of the hull. The higher the better. 'Course, that just depends on how much you don't care what it looks like, but much better range.

Something on the order of 27 inches has very little to do 'electrically' with 27 Mhz. One wave length at 27 Mhz is about 36 feet. A 1/2 wave is about 18 feet, and a 1/4 wave is about 9 feet (those steel whip thingies on the back of a CB'ers car, right?). The average 27 Mhz R/C antenna is something near 30 - 36 iinches. That's because that's a nice round number for the manufacturors, not really any electrical significance. A 'prefered' electrical length for an R/C receiver just isn't a 'biggy'. Definitely NOT true for a transmitter, though. As for using a receiving antenna with a 'load' or coil? Don't bother. Just getting it higher does much more.
- 'Doc