This is proof that Cox engines can do stunts (including inverted flying).

I flew Iyer's Combat model with Cox Black Widow and kite thread lines.
I never used Dacron thread, 7-strand wire, and spider/spectra lines for flying 1/2A models.

A pic of the ComBat...

Wonderful flying. Nice stance and control. Congrats.

I have used a 7-strand control line wire for a flying senior peacemaker with a 25LA, 15LA, 3.2cc Sharma diesel engine engine.

For flying 1/2A models, I never used Dacron thread, 7-strand wire, and spider/spectra lines.

There is a difference.