QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 41 Reply 1, posted (7 years 4 months 2 weeks 1 day 23 hours ago) and read 3066 times:
Wouldn't the rudder mounted so high make the aircraft roll more?
Yes - the higher the rudder the greater the associated tendency to produce a rolling force, simply due the increased moment arm from the rudder's applied force to the point about which it can be thought to act laterally, the aircraft's longitudinal axis. I think you'll find, however, that whatever small increase in rolling moment a slightly higher rudder contributes is quite imperceptible, at least in the grand scheme of things, and in any case it is not really a disadvantage per se.
As for actual advantages and disadvantages, I must admit I can't really think of any significant ones. There are certainly some pros and cons associated with overall tail size, especially in the realm of dutch roll tendency, spiral instability, and other stability issues, but I can't think of any major ones having to do with rudder height.
Oly720man From United Kingdom, joined May 2004, 6081 posts, RR: 12 Reply 2, posted (7 years 4 months 2 weeks 1 day 22 hours ago) and read 3042 times:
I think with the 3 holers there is the problem that the engine's there as well so the fin and rudder may be a bit higher than they would be with a comparable twin jet. With the DC10/MD11 compared to the L1011, the engine is higher up to start with so the fin/rudder will be high. This is probably why it's smaller than on other aircraft, to reduce the structural loading.
Man City p3 w3 d0 l0 f4 a0 P9 - hey it may never happen again!
SATL382G From , joined Dec 1969, posts, RR: Reply 3, posted (7 years 4 months 2 weeks 1 day 14 hours ago) and read 2981 times:
The size of the rudder is controlled, if I'm not mistaken, by the need to provide yaw authority in the engine out case. (the further out on the wing the engine is the more rudder needed to keep the aircraft flying straight if you shut that engine down).
So the 747 has lots of fin and rudder relative to the DC10. The L1011, I believe, has a larger rudder than the DC10. The L1011s engines are also mounted further outboard.
Dc10guy From United States of America, joined Feb 2000, 2685 posts, RR: 8 Reply 4, posted (7 years 4 months 2 weeks 1 day 4 hours ago) and read 2928 times:
The DC10 Rudder many seem small. But when you stand next to it ,,,it ain't that small. Remember that the higher the speed the less surface you need. Also the rudder is a 2 piece blown design. ( that's 2 pieces for each rudder upper & lower ) Its very effective at low speeds too.
Next time try the old "dirty Sanchez" She'll love it !!!
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