I have a roban Apache 700 that I'm slowly working on this is my first roban kit...

I know someone who can help. Standby.

So I have a Roban Apache. By default, it was designed so you would mount the ESC in the fuselage right in front of the mechanics, then, in front of that (just behind the nose) you would place your two 6-cell batteries. Your flight controller (and probably your receiver too) would mount on the mechanics behind the cyclic servos.

As you've now noticed, there isn't a lot of room in the fuselage for extraneous equipment. If you are planning on using a separate BEC and/or 2-cell battery for your electronics, you could probably mount them on inside of the fuselage up front in the recesses on the left and right sides. There should be enough room in those recesses so the cockpit will still fit without interference.

My setup is a giant mess with stuff everywhere because I just *had* to put a 2-speaker sound system in mine. So I have a speaker, a sound module, a small 6S battery to power the amp in the sound module, a 2-cell receiver battery and my two 6-cell 5000 packs all crammed in front of the mechanics. The only place for the ESC was the open area underneath the mechanics. It's super ugly, but it works.

Thank you Patrick

Following I also just received mine and am building it as I type.

Agree that it can be a challenge to get everything stuffed into the Apache fuselage, especially the batteries! I ended up cutting out some of the fibreglass to expand the internal bay into the EFABS, to allow the batteries to be fitted laterally (the attached photo shows what I mean). I also couldn’t resist adding other bits and pieces, like an arduino-controlled servo to control the tailplane position, and slew servos for the gun and turret!