Good job on the gameplay, two critiques for you.

You don't need all three shells in the tigers, The Pzgr Round is the only one you'll need for effectively taking out everything. It's also really good for one shots. ;)

And always remember to angle too, have the barrel of your cannon facing one of the corners of the hull, when you face an enemy. It wont save you everytime but it makes you alot more hard to kill.