There is absolutely no justification for not modeling armor on to the Apache helicopter. It is the most inane mistake this company has made. Borne from intentional laziness or unintentional asinine oversight it needs to be fixed.
Then you can post a bug report, have it denied for no reason, and complain with evidence!
There is no succinct source as the exact performance is classified. I would believe considering the limited information released to new organizations it would be more than the currently nothing rendered on the helicopter. It’s lacking even a plate of armor which even the AH-1G is afforded despite being built in 1970. Do you honestly think a mainline attack helicopter wouldn’t even have a single millimeter of armor? The KA-50 is afforded a plate of armor around its engine, why? From “sekret dokumentz”?
I’m sure it is, but with Gaijin it’s whatever they want until you can definitively prove otherwise (and even then…)
There’s open sources which list it capable of withstanding 12.7mm fire and the engines able to withstand 23mm fire. That not even a 15mm plate is modeled is egregious.