rwessel From United States of America, joined Jan 2007, 2145 posts, RR: 2 Reply 1, posted (11 months 2 weeks 1 day 21 hours ago) and read 2667 times:
Not really. Compared to the mass of the aircraft, the effect is pretty small, particularly since much of the rotating mass is in the relatively small diameter section of the engine. Some engines do have counter-rotating shafts, and that will obviously reduce the effect, but it's not a prime consideration.
Jetlagged From United Kingdom, joined Jan 2005, 2509 posts, RR: 24 Reply 3, posted (11 months 2 weeks 1 day 14 hours ago) and read 2466 times:
For a V/STOL aircraft like the Harrier gyroscopic precession is important as it adversely affects hovering stability. That's why the Pegasus engine has counter-rotating shafts. Counter rotating shafts in engines like the RR Trent are more for aerodynamic reasons than to reduce precession torque. Airliners don't usually pitch or yaw at high rates so any precession torque will be relatively low, but it is taken into account when stressing the engine mountings. It's more likely to be significant in a military fighter as a rapid pitch up will create a yawing moment.
The glass isn't half empty, or half full, it's twice as big as it needs to be.