Guys I just bought a Flysky-Ct6b transmitter and going through the forums I found out that the normal non-rechargeable AA batteries just survive 20 -30 mins tops. Most recommended using rechargeable NiMH/NiCd batteries which lasts much longer. But these batteries only provide 1.2V, totaling 9.6V (1.2 x 8) whereas ct6b requires 11.1V. Would this be an issue?

Extract from CT6B manual

The CT6B has a cheap LM7805 5v linear regulator inside it. This means the input voltage has to be a minimum 6.5 volts before the transmitter shuts off. At fully discharged conditions, each battery will be at 0.9v, meaning 7. 2 v total input voltage.
So technically you should be able to use the batteries without any worries.

Note: The linear voltage regulator inside it is very inefficient, consider looking at some mods if you're comfortable with them.
Cheers!