QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 35 Reply 1, posted (9 years 1 month 4 weeks 9 hours ago) and read 4516 times:
This should answer your question. As explained there, MD-80 engines are angled in such a way to align them better with "clean" airstream -- in short, for airflow reasons.
DeltaGuy From , joined Dec 1969, posts, RR: Reply 2, posted (9 years 1 month 4 weeks 7 hours ago) and read 4364 times:
So I also hear, it's a good thing to help prevent FOD (foreign object damage)...not sure where it came from, so don't quote me But the aero charactersitics are more important there...
QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 35 Reply 3, posted (9 years 1 month 4 weeks 6 hours ago) and read 4267 times:
I'm sure the "engine tilt" helps to reduce FOD to a very -- I repeat, very --limited extent, but, as you said, airflow orientation is the major consideration involved.
CFIcraigAPA From United States of America, joined Jan 2004, 223 posts, RR: 4 Reply 4, posted (9 years 1 month 4 weeks 2 hours ago) and read 4196 times:
This should help too. It's not just for airflow reasons, look for my reply about four or five down.
CM
Vikkyvik From United States of America, joined Jul 2003, 8210 posts, RR: 28 Reply 5, posted (9 years 1 month 4 weeks ago) and read 4167 times:
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Jgore,
The inlets are slanted upwards in order to alighn the intakes with the local airflow, as it has been disturbed by the wings and fuselage.
CFIcraigAPA,
In the reply in the linked thread, you stated that the horiz. stab. gives a nose-down moment, which is not correct. The H-stab gives a nose-up moment; it's an inverted airfoil, meaning it's generating lift downwards, which would obviously cause the tail end to lower and the nose to raise.
Also, adding power will cause a nose-up moment as well. The whole reason the H-stab is in existence is because the center of lift is ahead of the CG, therefore, causing a nose-up moment. Adding power will increase the aircraft speed, therefore increasing the lift. As far as as I know, this will counteract the very slight nose-down moment created by the engines increasing their thrust.
Someone correct me if I'm wrong.
~Vik
"Two and a Half Men" was filmed in front of a live ostrich.
Darkblue From United States of America, joined Sep 2003, 233 posts, RR: 11 Reply 6, posted (9 years 1 month 3 weeks 6 days 21 hours ago) and read 4131 times:
This topic has been discussed before, you may want to do a search.
Note that it is the inlets of the engines that are facing up, not the actual engine. Aft-mounted engines are in the downwash of the wing so the inlets usually face upward to be aligned with the flow. Wing mounted engines are in the upwash of the wing and the inlets usually face downward to be aligned with the flow.
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From Australia, joined Dec 2003, 1500 posts, 
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But the aero charactersitics are more important there...
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