Another consideration is the fuel tanks. Tried desperately to get some photos of the fuel tanks FEJ use but couldn't until the Viper S arrived.

There are two small half tanks in the bottom of the fuselage just aft of the mid section bulkhead. Each tank completely full only has 1300mls in it, so a total of 2600mls. I'm planning on running an ATJ120Ti so think I will need at least 4000mls for a decent 10 min flight time with reserves.