Just to expand on the comments on RCG regarding converting MK classics to electric, the main challenge is to figure out how to gain access to the LiPo pack - ideally from the top. Locating a 6s5000 pack in the tank compartment is a non-issue as they’re smaller than a 16 (even 12 in some cases) oz tank. Some weight redistribution of the radio may be needed due to the additional “nose” weight brought about by the motor/ESC/LiPo combo which weight more than an engine/tank and fuel. Wisely locating servos and the radio pack usually solves this problem including the possibility of installing twin elevator servos in the tail boom. Sometimes the radio battery also needs to sit behind the wing TE under a hatch much in the same way that the tail servos are located in the MK Skymaster.

A little creative former redesign and lite ply floor additions in the canopy area can produce a removable assembly for access to the LiPo located on a tray with the motors ESC just aft of the FW which can be moved forward a fair amount given the requirements of 50 mm can outrunner.

Also, Mike Seale scratch built both a BA as well as an Atlas using the same electric retracts and electric power systems. Here are the build logs and an excellent reference:

https://www.rcgroups.com/forums/show...-pre-build-log

https://www.rcgroups.com/forums/show...?2542547-Atlas

David