Is the MD-11's third engine slightly nose up?












3














From my visual inspection, the third engine (the engine on the horizontal stabilizer) is slightly "nose up", especially compared to the engines on the wing. That means, the front part of the engine is lifted slightly. Am I correct? If yes, what is the intention?



McD11 with its third engine






aircraft-design aircraft-performance md-11







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  • Closely related
    – Pondlife
    2 days ago
















3














From my visual inspection, the third engine (the engine on the horizontal stabilizer) is slightly "nose up", especially compared to the engines on the wing. That means, the front part of the engine is lifted slightly. Am I correct? If yes, what is the intention?



McD11 with its third engine






aircraft-design aircraft-performance md-11







share|improve this question
























  • Closely related
    – Pondlife
    2 days ago














3












3








3







From my visual inspection, the third engine (the engine on the horizontal stabilizer) is slightly "nose up", especially compared to the engines on the wing. That means, the front part of the engine is lifted slightly. Am I correct? If yes, what is the intention?



McD11 with its third engine






aircraft-design aircraft-performance md-11







share|improve this question















From my visual inspection, the third engine (the engine on the horizontal stabilizer) is slightly "nose up", especially compared to the engines on the wing. That means, the front part of the engine is lifted slightly. Am I correct? If yes, what is the intention?



McD11 with its third engine






aircraft-design aircraft-performance md-11




aircraft-design aircraft-performance md-11






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 2 days ago









Pondlife

50.3k8135278




50.3k8135278










asked 2 days ago









AirCraft LoverAirCraft Lover

400112




400112












  • Closely related
    – Pondlife
    2 days ago


















  • Closely related
    – Pondlife
    2 days ago
















Closely related
– Pondlife
2 days ago




Closely related
– Pondlife
2 days ago










3 Answers
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6














Yes, there is a slight tilt to the engine. Engines are heavy, so placing them on the tail shifts the center of mass towards the tail, which is not good for stability. To counter this, aircraft with rear engines often tilt the engines slightly, so the thrust they produce can offset their own weight, helping with stability. It's extremely slight though, as large angles can produce major pitch oscillations with power changes (something known as pitch coupling).



enter image description here






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New contributor




Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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    2














    I believe it has a 4deg incline to align the exhaust with the drag from the fuselage.



    It appears more because the inlet is higher than the engine.



    http://drawingdatabase.com/mcdonnell-douglas-md-11/






    share|improve this answer





























      0














      It may be for the same reason down thrust angle is commonly put into tractor engine mounts - to compensate for pitch up tendency of air craft as they accelerate from added thrust leading to increased velocity.



      The third engine of the tri-jet is simply pushing the tail up as thrust is applied. This is something very beneficial in the event of a power-on stall as it assists the elevator in
      lowering the nose.



      Adding up thrust in the back to compensate for weight imbalance would have to be questioned from an engineering point of view, as failure of this engine would create a dangerous aft CG imbalance. It is wise not to rely on thrust or trim to correct an out of safe
      range CG. Better to move the wing back a bit, as long as it is still directionally stable.






      share|improve this answer





















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        3 Answers
        3






        active

        oldest

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        3 Answers
        3






        active

        oldest

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        active

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        active

        oldest

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        6














        Yes, there is a slight tilt to the engine. Engines are heavy, so placing them on the tail shifts the center of mass towards the tail, which is not good for stability. To counter this, aircraft with rear engines often tilt the engines slightly, so the thrust they produce can offset their own weight, helping with stability. It's extremely slight though, as large angles can produce major pitch oscillations with power changes (something known as pitch coupling).



        enter image description here






        share|improve this answer








        New contributor




        Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
        Check out our Code of Conduct.























          6














          Yes, there is a slight tilt to the engine. Engines are heavy, so placing them on the tail shifts the center of mass towards the tail, which is not good for stability. To counter this, aircraft with rear engines often tilt the engines slightly, so the thrust they produce can offset their own weight, helping with stability. It's extremely slight though, as large angles can produce major pitch oscillations with power changes (something known as pitch coupling).



          enter image description here






          share|improve this answer








          New contributor




          Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.





















            6












            6








            6






            Yes, there is a slight tilt to the engine. Engines are heavy, so placing them on the tail shifts the center of mass towards the tail, which is not good for stability. To counter this, aircraft with rear engines often tilt the engines slightly, so the thrust they produce can offset their own weight, helping with stability. It's extremely slight though, as large angles can produce major pitch oscillations with power changes (something known as pitch coupling).



            enter image description here






            share|improve this answer








            New contributor




            Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.









            Yes, there is a slight tilt to the engine. Engines are heavy, so placing them on the tail shifts the center of mass towards the tail, which is not good for stability. To counter this, aircraft with rear engines often tilt the engines slightly, so the thrust they produce can offset their own weight, helping with stability. It's extremely slight though, as large angles can produce major pitch oscillations with power changes (something known as pitch coupling).



            enter image description here







            share|improve this answer








            New contributor




            Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.









            share|improve this answer



            share|improve this answer






            New contributor




            Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.









            answered 2 days ago









            Nathan ChetramNathan Chetram

            1162




            1162




            New contributor




            Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.





            New contributor





            Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.






            Nathan Chetram is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.























                2














                I believe it has a 4deg incline to align the exhaust with the drag from the fuselage.



                It appears more because the inlet is higher than the engine.



                http://drawingdatabase.com/mcdonnell-douglas-md-11/






                share|improve this answer


























                  2














                  I believe it has a 4deg incline to align the exhaust with the drag from the fuselage.



                  It appears more because the inlet is higher than the engine.



                  http://drawingdatabase.com/mcdonnell-douglas-md-11/






                  share|improve this answer
























                    2












                    2








                    2






                    I believe it has a 4deg incline to align the exhaust with the drag from the fuselage.



                    It appears more because the inlet is higher than the engine.



                    http://drawingdatabase.com/mcdonnell-douglas-md-11/






                    share|improve this answer












                    I believe it has a 4deg incline to align the exhaust with the drag from the fuselage.



                    It appears more because the inlet is higher than the engine.



                    http://drawingdatabase.com/mcdonnell-douglas-md-11/







                    share|improve this answer












                    share|improve this answer



                    share|improve this answer










                    answered 2 days ago









                    AnilvAnilv

                    2,7591011




                    2,7591011























                        0














                        It may be for the same reason down thrust angle is commonly put into tractor engine mounts - to compensate for pitch up tendency of air craft as they accelerate from added thrust leading to increased velocity.



                        The third engine of the tri-jet is simply pushing the tail up as thrust is applied. This is something very beneficial in the event of a power-on stall as it assists the elevator in
                        lowering the nose.



                        Adding up thrust in the back to compensate for weight imbalance would have to be questioned from an engineering point of view, as failure of this engine would create a dangerous aft CG imbalance. It is wise not to rely on thrust or trim to correct an out of safe
                        range CG. Better to move the wing back a bit, as long as it is still directionally stable.






                        share|improve this answer


























                          0














                          It may be for the same reason down thrust angle is commonly put into tractor engine mounts - to compensate for pitch up tendency of air craft as they accelerate from added thrust leading to increased velocity.



                          The third engine of the tri-jet is simply pushing the tail up as thrust is applied. This is something very beneficial in the event of a power-on stall as it assists the elevator in
                          lowering the nose.



                          Adding up thrust in the back to compensate for weight imbalance would have to be questioned from an engineering point of view, as failure of this engine would create a dangerous aft CG imbalance. It is wise not to rely on thrust or trim to correct an out of safe
                          range CG. Better to move the wing back a bit, as long as it is still directionally stable.






                          share|improve this answer
























                            0












                            0








                            0






                            It may be for the same reason down thrust angle is commonly put into tractor engine mounts - to compensate for pitch up tendency of air craft as they accelerate from added thrust leading to increased velocity.



                            The third engine of the tri-jet is simply pushing the tail up as thrust is applied. This is something very beneficial in the event of a power-on stall as it assists the elevator in
                            lowering the nose.



                            Adding up thrust in the back to compensate for weight imbalance would have to be questioned from an engineering point of view, as failure of this engine would create a dangerous aft CG imbalance. It is wise not to rely on thrust or trim to correct an out of safe
                            range CG. Better to move the wing back a bit, as long as it is still directionally stable.






                            share|improve this answer












                            It may be for the same reason down thrust angle is commonly put into tractor engine mounts - to compensate for pitch up tendency of air craft as they accelerate from added thrust leading to increased velocity.



                            The third engine of the tri-jet is simply pushing the tail up as thrust is applied. This is something very beneficial in the event of a power-on stall as it assists the elevator in
                            lowering the nose.



                            Adding up thrust in the back to compensate for weight imbalance would have to be questioned from an engineering point of view, as failure of this engine would create a dangerous aft CG imbalance. It is wise not to rely on thrust or trim to correct an out of safe
                            range CG. Better to move the wing back a bit, as long as it is still directionally stable.







                            share|improve this answer












                            share|improve this answer



                            share|improve this answer










                            answered yesterday









                            Robert DiGiovanniRobert DiGiovanni

                            1,6331315




                            1,6331315






























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