If it's one of these cheap transmitters: http://www.giantshark.co.uk/product/...e2-transmitter

then they do have a mixing option. Open the battery compartment cover and look in the little gap at the top left-hand corner. There should be a small silver and white slide switch there that allows you to turn mixing on/off. When on, this will give you single stick control on the right-hand stick.

Alternatively, yes an external mixer (that plugs in between your ESCs and receiver) will do the job. Giant Shark also have a pretty cheap one that works: http://www.giantshark.co.uk/product/...--v-tail-mixer