No, they will max out between 1.4V and 1.45V, but this voltage will drop off like a rock as soon as a load is applied. A 9C will display 11.4V at most fresh off charge with Nimh or Nicd, and quickly drop to the high 10's.
A Lipo will deliver 12.6V for some time. The issue is with the radios regulator, at that voltage it will run hotter. Now the bigger issue comes in with running a 72Mhz RF module. In this case there is no voltage regulator. Full battery voltage is used for the final RF output. Futaba Mhz RF modules were not very tolerant of running with the antenna collapsed for any length of time. Run a full 12.6V to the RF module and then do a range test, that extra voltage will eventually kill the output transistor. The safest way to run a 3S lipo in any 8 cell transmitter is to add 2 diodes in the battery output. That will drop the 12.6V of the battery down to about 11.4V to the radio (I've done it with my 9C), better yet, if you run it to low voltage warning, then the lipo will not be over discharged. Adding the diodes also has the added safety benefit of disabling the regular charge jack, you will only be able to charge thru the balance tap, a good thing in my opinion