I cannot understand how afterburner fuel nozzles are not crating a lot of backpressure and allow engine to work when afterburner is not in use? They close almost 50% of the exhaust area. Is there any efficiency loss during normal operation? Can nozzles move out of the stream when afterburner is not in use?
[![enter image description here](https://i.stack.imgur.com/ia753.jpg)](https://i.stack.imgur.com/ia753.jpg)