Background are problems modeling the rotax 912 engine. The idle speed
of the real engine is about half of the speed I could achieve with the
default minimum manifold pressure. While on ground I can switch off
the engine by pulling the throttle. The audible difference between the
different minimum idle speed (real vs. simulated) is extreme. With the
patch I get quite realistic sound. For the rotax engine I use
min-throttle="0.05" which is half of the former default value.