Since my heli was grounded, I had a lot of bench time in the last few days. Let's show the progression of where I have it mounted.
My original design:
My daughter said that it looked too "wirey". I kinda agree.
Few crashes later, took them all apart.
Trying out mounting it under the heli using the APM1 mounting plates. It looks super clean. I really like it.
But there are not enough clearance between the 2 mounting plates to give the APM2 some proper anti-vibration paddings. The heli was quite uncontrollable... and crashed.
So, back to the first design, but this time, I make the bottom plate bigger. Later, I can make some sort of cover for the board and sit on this bottom plate.
As you can see, there are quite a bit of space on both sides to mount a cover on it.
There are 2 modifications over my original design. Foam pad directly stick to the APM board to avoid any standing wave between the 4 corner screws/standoffs. Added a heavy copper plate under the APM2. It should decrease the vibes on the APM greatly.
Now I look at it, I should have completely replace the middle blank PCB with a copper plate and have the APM2 mount directly on it with the standoffs.