newagebird
Posts: 63
Joined: Sat Sep 03, 2005 8:51 am

Are Trijets Easier To Fly In Engine Failure

Fri Jan 27, 2006 10:44 am

Hey everybody,
I havent completed a twin engine endorsement therefore i have little understanding of the topic. I hear that in a twin engine, if u had an engine failure u had to apply full opposite rudder and then trim the aircraft to compensate for assymetric thrust.
With a tri-jet such as the MD-11 or L-1011, is it a lot more easier to fly if the port engine (for example) fails?
Also is it possible to fly with only one engine functioning in a tri-jet.
Thanks
rgds newagebird
 
2H4
Posts: 7960
Joined: Tue Oct 19, 2004 11:11 pm

RE: Are Trijets Easier To Fly In Engine Failure

Fri Jan 27, 2006 10:52 am




Quoting Newagebird (Thread starter):
With a tri-jet such as the MD-11 or L-1011, is it a lot more easier to fly if the port engine (for example) fails?

Failure of a wing-mounted engine is going to result in asymetric thrust and drag regardless of the number of engines.

Failure of a tail-mounted engine on a tri-jet, however, will not affect the directional stability or control, because that engine is perfectly centered along the longitudinal axis of the aircraft.




Quoting Newagebird (Thread starter):
Also is it possible to fly with only one engine functioning in a tri-jet.

It would depend on a number of things. Particularly, aircraft weight.

By the way...welcome to A.net!




2H4


Intentionally Left Blank
 
User avatar
Jetlagged
Posts: 2562
Joined: Sun Jan 23, 2005 3:00 pm

RE: Are Trijets Easier To Fly In Engine Failure

Fri Jan 27, 2006 11:01 am

Not really any different, since the centre engine does not affect the asymmetric yawing moment of the good wing mounted engine. Unless of course it is the centre engine which fails  Smile

On the basis that the L-1011, DC-10 and MD11 are really over-powered twins, you should be able to maintain height on one engine, though not full cruising altitude. Performance would depend on aircraft weight and ambient conditions. Obviously climbing, let alone takeoff, would be out of the question, however one engine on a trijet should get you safely to a nearby alternate.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
474218
Posts: 4510
Joined: Mon Oct 10, 2005 12:27 pm

RE: Are Trijets Easier To Fly In Engine Failure

Fri Jan 27, 2006 11:37 am

Look at the wing engines on the DC-10 and MD-11, you will see that they are in close to the fuselage. This is to compensate for a wing engine failure. They are trying to keep the thrust as close to the center line as possible. The wing engines on the L-1011 are out further away from the fuselage. The reason the L-1011 can have its engines further away from the fuselage than the DC-10 and MD-11 is that the placement of the L-1011's center engine provides better center line thrust and the L-1011 has a much greater vertical stabilizer surface area then the DC-10 or MD-11. Failure of the center engine on any of the tri-jets does not produce asymmetrical thrust. Flying on two engines it is possible to maintain altitude (depending on weight and altitude) but with just one engine operative, you should be looking for a place to put it down fairly quick.
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: Are Trijets Easier To Fly In Engine Failure

Fri Jan 27, 2006 2:06 pm

Examples,
L1011-100, RB.211-22B engines, AUW 200,000kg, ISA+10
Max altitude all engines operating, FL330
2 engines operating, FL190
1 engine operating, 6,000 feet

L1011-250, RB.211-524B402 engines, AUW 200,000kg, ISA+10
Max altitude, all engines operating, FL350
2 engines operating, FL260
1 engine operating, 12,000 feet

With both aircraft, with one engine inoperative, fuel burn increases 500kg/hour, approximately, with the 2 engine cruise speed of 440 KTAS
 
KevinL1011
Posts: 2858
Joined: Fri Mar 04, 2005 3:48 pm

RE: Are Trijets Easier To Fly In Engine Failure

Fri Jan 27, 2006 4:06 pm

Quoting 474218 (Reply 3):
The reason the L-1011 can have its engines further away from the fuselage than the DC-10 and MD-11 is that the placement of the L-1011's center engine provides better center line thrust

And, should one fall off.... or grenade...the ship is still flyable!  Wink

Quoting 2H4 (Reply 1):
Failure of a tail-mounted engine on a tri-jet, however, will not affect the directional stability or control

I know of a UAL crew who had a hard landing in Iowa that might dispute this. razz 

Please, do not think I am bashing the DC-10. The 10 is a superb freighter and tanker. Just don't transport any PAX in one.  biggrin 

Pls. give me a minute to find my nomex underwear.  flamed 
474218, Carl, You will be missed.

Who is online

Users browsing this forum: No registered users and 24 guests