Upsmd11 From United States of America, joined May 2003, 816 posts, RR: 4 Posted (11 years 6 months 2 weeks 1 hour ago) and read 6779 times:
I have always wondered what the fins are on the fuselage of the MD-80's. A friend of mine who works for DL once told me they were steps so MX could wash the windows but I doubt this as the DC-9's don't have them.
Techspec From United States of America, joined Sep 2001, 70 posts, RR: 0
Reply 3, posted (11 years 6 months 1 week 6 days 22 hours ago) and read 6712 times:
If my memory is correct. The MD80 strakes were installed to assist airflow across the Vertical Stab and elevators during high angle of attack situations. Prevents what is called "tail" stall. From what I was told in certain flight profiles (nose high) the wings had a tendency to rob airflow from the elevators. So the story goes....
Also, the engines have similar strakes on them also.
FBU 4EVER! From Norway, joined Jan 2001, 998 posts, RR: 7
Reply 4, posted (11 years 6 months 1 week 6 days 17 hours ago) and read 6686 times:
The nose strakes were introduced on the DC-9-50 to improve the directional stability and aerodynamic airflow at high angles of attack and certain flap positions.The DC-9-40 had an internal mechanical solution to this problem,but this was deemed uneccessesary with the arrival of the strakes.On the DC-9-50 and MD-80 series the strakes are anti-iced by bleed air via the airfoil anti-ice switches,on the MD-90 they are electrically heated.
The engine nacelle strakes were introduced on the MD-80 series for another reason,namely stall recovery.They add area which in turn adds drag and in a stall condition,this will help the nose drop faster than the tail.On the MD-90,with it's much heavier engines,there are small "flaps" at the trailing edge of the engine pylons in addition to the nacelle strakes.These operate only in the air and when the control column has reached it's fully forward position.The nacelle strakes are not heated in any way.