rocket stove II

I finally got my hands on a big tin so tried to make a better version of the rocket stove.It was tidy and smaller than the first effort, I think there was less smoke and less wood used to boil 800ml of water in the kettle but alas I was disappointed by the time – 19mins. Only 1min quicker than the first effort!
It still doesn’t seem very efficient to me, I’m sure it could be quicker than that.  I want it down to 10mins.