Thanks Matt,
I like the cutaway, and remember the CF6 well (in its Dash-50 and Dash-80 form). Must admit that I'd wondered about the effect of the stator blades in the duct, as well as the VSVs (variable-pitch anti-compressor-stall stator-vanes).
I hear what you say re fan speed. But I also recall that one of the main limitations on propeller rpm is the tips going supersonic. How does that make the fan always "faster"? As for the fan blades being "very small in comparison with the size of the disc", have you looked at some of the more recent designs? The old CFM-56 ones are quite big (only about 32 to fill the circumference, as I recall), the V2500 bigger, and so on.
OK, I'm a bit out of my depth in this argument of semi-ducted fans with stators; versus unducted propellers. But, in addition to wake turbulence issues caused by wing-tip vortices, I remain to be convinced that jet-engine slipstream, for want of a better word, is completely non-vortex.
As for fan slipstream, and its possible effect on the fin and rudder, I will buy dinner for any (one!) forumite who can disprove my contention that it is noticeable as you spool up the CFM-56 engines of an A320 on a rolling crosswind take-off. [Yes, I'm aware it's got rudder-fine steering.]
Chris
Last edited by Chris Scott; 29th Feb 2008 at 12:07.
Reason: VSV terminology