Mr Spaceman From Canada, joined Mar 2001, 2786 posts, RR: 9 Posted (11 years 12 months 1 day 8 hours ago) and read 5361 times:
In the photos below of the TU-154, you can clearly see that the 2 side-mounted engines are angled so that their tailpipes are pointed inward toward the fuselage. Why is this done? Is it for aerodynamic reasons that involve the direction of engine thrust, such as directional stability? Could it be for mechanical reasons?
Also, do any airliners that have only wing mounted engines such as the 747, 777, A320, A340 etc, have their engines mounted on an angle? Or even an L-1011 or DC-10...are their wing mounted engines on an angle?
Mr Spaceman From Canada, joined Mar 2001, 2786 posts, RR: 9 Reply 4, posted (11 years 12 months 1 day 6 hours ago) and read 5183 times:
Hi guys. Thanks for your replies.
>VC-10, like always, you are a great source of info. OK, the inboard engines of a 747 are canted 3 degrees in order to catch the "Bow Wave". I suspect you mean the "front" of the engines are angled inward because a bow wave sounds like a wave of airflow which would be flowing rearward off the nose. Could I be correct? And if so...are the inboard engines set up differently than the outboard ones, because of this bow wave?
Here's a cool pix showing a 747's profile from below. You can almost see the 3 degress...I think.
>Mandargb, I believe you are "right on the money" regarding your observations of the horizontal angle of the engines on MD-80's It looks to me like the front of the engines are angled upward a few degrees.
Here's some photos that clearly show the different angle between the fuselage and the engines.
Goldenshield From United States of America, joined Jan 2001, 5643 posts, RR: 15 Reply 6, posted (11 years 12 months 1 day 1 hour ago) and read 5119 times:
I have read this somewhere else, but the reason why the the engines on the 727, and Dc-9 series are angled upwards is so that the intake does not get the spoiled air off the wings, when at a relatively high AoA.
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Mr Spaceman From Canada, joined Mar 2001, 2786 posts, RR: 9 Reply 8, posted (11 years 12 months 14 hours ago) and read 5075 times:
I had a feeling the engines were canted inward for aerodynamic reasons such as directional stability (around the vertical axis).
In the photos below of some CRJs, you can see that the engines are indeed canted inward just a little. It also appears that they are angled horizontally so that the intake is a bit higher than the exhaust.
VC-10 From United Kingdom, joined Oct 1999, 3691 posts, RR: 35 Reply 9, posted (11 years 12 months 9 hours ago) and read 5057 times:
Looking at my course notes both the inbd & otbd 747 nacelles are canted in 2 degs to pick up the bow wave.
On the VC10 in an effort to reduce the unexpectedy high drag encountered during flight testing, the Super VC10 engine nacelles were attached to the fuslage at a 3 deg nose up angle and the stub wing span increased to get the inbd engine intakes out of the 11 inch thick boundary layer in that area.
TimT From United States of America, joined Jun 2001, 168 posts, RR: 0 Reply 12, posted (11 years 12 months 5 hours ago) and read 5017 times:
Here's another tidbit-- the DC-10 likes to fly between 3 and 5 degrees nose up. Not sure about the others, but I suspect the same thing. If that's the case, the engineering department canted the engines so they are "square" to the airflow. I know that on a ground runup, it's a really bad idea to pull high power without being pointed into the wind. Makes exciting things happen. (including getting yelled at)
Jetguy From , joined Dec 1969, posts, RR: Reply 13, posted (11 years 12 months 4 hours ago) and read 5016 times:
One more tidbit you you guy that are interested in Learjets. On all but the earliest tip-tanked models the tip tanks are canted downward 3 degrees (as I remember) to keep them square with the world during crusing flight at altitude. One of the explinations that I remember from one of my type rating ground schools regarding the outward canting of the engines (as seen from the front) was to minimize the rudder forces required in the case of engine loss. Whether or not that's a valid reason, I honestly don't know but it sounds good and does make some sense. It's common to mount the engines on larger sengle-engine aircraft with a significant cant. Next time you get a chance go look at a late model Bonanza. It will really surprise you. You'd think the airplane would fly sideways through the air.