MD-88 question

[blzr]

Why are the engines on the MD-88 tilted slightly up? Does it have to do with the angle of attack at cruise?

 

[FR8mastr]

I dont fly one, I am also curious as to the reasons. I dont think they are angled up for angle of attack in cruise, because it already fly's with a nose high attitude. That would make the engines even higher. My guess is it is because of the airflow over the wings. Anyone know for sure??

 

[jetdawg]

This Is What I Was Told Back 5 Years Ago For My Initial Dc-9 Newhire Trng. (if Not Correct Do Not Kill Me My Instructor Has Since Commited Suicide So Not Sure What State Of Mind His Was In) I Would Assume The Same For The Md-88


Douglas Was Competing With Boening And When The Dc-9 Was Fed Tested In The 60's The V1 Cut Produced Very Little Yaw So It Was To Be Certified As Centerline Thrust. Douglas Said Heck No We Are Competting With The 737 And We Can Not Have A Centerline Thrust Limititation (not Sure Why) Anyway They Canted The Engines Upward So It Would Prodce A Rolling Tendency. With This Cant Upward They Were Able To Not Have A Centerline Thrust Issue.

That Is What I Have Been Told And I Am Sticking To It. (for Now)

 

[rptrain]

now that's a training department rumor if i've ever heard one.

 

[dane]

Well,

I have flown the MD close to 5.5 years now. I have never heard why the engines are canted upwards. I do not believe the story about centerline thrust limitation. When we do v1 cuts in the sim it definetely produces a yaw. I tend to think that the airflow over the wing has something with it. Any jet engine likes a clean, undisturbed airflow to enter at the front. As the airflow departs the aft wing edge it has a downward direction. By angling the engine slightly upwards the risk of ingesting anything is further reduced.

Any takers??

dane

 

[XRMEFLYER]

I'll buy that!

 

[pooter]

come on guys its so simple,you must need a refresher course.thrust vector.

 

[LarryinTN]

When you make power changes on the DC9 there is no immediate pitch up or pitch down. Seems like the angle of the engine is set to prevent trim changes with power changes.

BTW, if the power change results in a change in airspeed that's when the trim changes.

 

[AA717driver]

Actually it's because McD-D never threw away any parts and some of the rear fuselage ribs were from C-54's. Because of the way the tail is mounted, the engine mounts on the MD80's had to be canted down a little in the rear. It's for stress.

Can anyone tell us how many parts on the MD80 were originally on the DC1? TC

 

[flx757]

Can anyone tell us how many parts on the MD80 were originally on the DC1? TC

Probably the mirror used to view the standby compass...

 

[CA1900]

You guys have it all wrong.

The engines are tilted upwards in case of a separation of the engine from the fuselage. Because the engines are mounted so close to the centerline, there was a real possibility that crews wouldn't realize there had been an engine separation because there wouldn't be any significant yaw without the engine there windmilling.

By tilting the engines upward a few degrees, it ensures that when an engine comes off, it will take a trajectory that will launch it so as to drop down in front of the cockpit window, ensuring that the pilots are aware of the problem.

 

[pianoman]

I heard it was to pitch the nose down when applying thrust in a stall recovery.

 

[FLB717]

Window Handle Ball was on all DC models, but maybe the DC10/MD11. On earlier models those Balls were on the Throttle Quadrant Levers for Throttle/Prop/Mixture.

 

[Chicken Taco]

Can't say for sure about the Mad Dog, but I drive the ERJ, which is a VERY similar airplane in overall shape and layout (albeit smaller scale). Our engines also have a slight upward tilt (not as much as an MD, but it's noticable.) The reason is to align the nacelle with the localized airflow in flight. As stated above jets like a smooth flow of air, and the best way to do this in the downwash aft of the wing is to align the intake with the localized flow. Aligned intake=smoother flow, since there would otherwise be a stagnant area on the upper fan face inside of the lip due to the downward flow of the air..

..CT

 

[LarryinTN]

I heard it was to pitch the nose down when applying thrust in a stall recovery.

But the nose doesn't pitch down when applying power...

 

[pianoman]

Ah, well there you are then. Shows what my friend knows.

 

[GogglesPisano]

Is it possible that the thrust is more aligned with the longitudinal access than the nacelles would have it appear? There may be a lot of accessories in that nacelle that distort it's shape.

 

[Dorkpilot]

What Chicken Taco said

When I went through GS on the 80, the instructor said almost exactly what Chicken taco stated. The angle only appears like a large one because the engine nacelles are so long. I belive it is only 3 degrees. The net effect on the forward thrust is negligible, but the ram air from over the wings increases the efficiency of the engine dramatically.

 

[FirstMate]

Where is bafanguy when you need him...

 

[AA717driver]

Window Handle Ball was on all DC models, but maybe the DC10/MD11. On earlier models those Balls were on the Throttle Quadrant Levers for Throttle/Prop/Mixture.

So are you saying that DC10/MD11 pilots have no balls? TC