Announcement

Collapse
No announcement yet.

Question: If for arguments sake the elevator cable

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Question: If for arguments sake the elevator cable

    snapped during flight in say a Cherokee would that render the aircraft uncontrollable about the lateral axis? Or would there be a degree of pitch control through the trim?

    My guess is the rudder would stay in the full nose up or nose down position & no trim input would change that? and the only real chance of pitch control would be through throttle inputs (less throttle = lower nose attitude & vice versa).

    Your thoughts please.

  • #2
    Originally posted by Messerschmitt Man
    snapped during flight in say a Cherokee would that render the aircraft uncontrollable about the lateral axis? Or would there be a degree of pitch control through the trim?

    My guess is the rudder would stay in the full nose up or nose down position & no trim input would change that? and the only real chance of pitch control would be through throttle inputs (less throttle = lower nose attitude & vice versa).

    Your thoughts please.


    In a light aircraft, as long as you maintain speed, some pitch control can be maintained using the Elevator trim, but it would not be sufficient to Flare the aircraft for landing. About the only option one would have is to attempt a high speed landing where decent would be minimized by the speed..... but then there's the issue of having enough room to perform such a maneuver! Maybe over a dry lake bed, maybe?

    **The "Rudder" has nothing to do with Pitch control**

    Unless one has their sh*t wired extrememly tight, and is blessed with an exceptional amount of luck, chances are they wouldn't walk away from it.

    Take care,
    Frank
    "Don't aftermarket details save lots of trouble?"
    "Only if you'd rather spend less time modeling!"

    Comment


    • #3
      I've seen a trim-only landing on a seminole when they lost control over the elevator for some reason (I can't remember why).

      All a bit of a non event... they trimmed the aircraft at a slowish speed for a low rate of descent for final, and then just quickly run a bit more in for a "flare". The throttle provides significant nose up/down moment on light aircraft.

      Reasonably firm landing but nothing worse than I usually do when everything was normal *grin*.

      Haven't tried it personally though!

      Comment


      • #4
        Sean Tucker lost control of his elevator in April 06 and used the elevator trim to control the A/C to get it to a safe area to bail out.

        Here is the NTSB findings on that accident.

        http://ntsb.gov/ntsb/brief2.asp?ev_i...06LA094&akey=1
        Robin Guess Aviation Historian, Photographer, Web Designer.

        http://www.Jet-Fighters.Net
        http://www.Jet-Liners.Net

        Comment


        • #5
          Many trim only landings have been made over the years. A few were actually accomplished because the primary control cables had sheared.

          I used to practice a trim only landings in C-150's and C-172's. It works well with a 0 flap approach, speed 80 knots all the way to the runway. Fly it on at 100 - 200 FPM rate of descent, no flair, ground effect will cushion the touch down, throttle to idle, normal braking. Distance for the 150 is about 1500 feet. A little more for the 172.

          In the 80's a Reeve Aleutian L-188 Electra lost #4 prop. It sliced through the fuselage severing ALL primary flight controls and ALL engine controls. The Aircraft was on a flight fro Cold Bay (PACD / CDB) to Seattle (KSEA / SEA) and diverted to ANC. I witnessed the landing. The crew landed the aircraft by shutting down engines as they approached ANC. Made a low (approach with #2 and 3 providing power) to prove they had enough control to attempt a runway landing. If not, they were planning on landing on the mud flats in Cook Inlet. Beautiful landing using only trim. The aircraft ran off the runway at the end of the roll out. No injuries.

          Don
          Refugee from ADC
          Don
          Standard practice for managers around the world:
          Ready - Fire - Aim! DAMN! Missed again!

          Comment


          • #6
            Originally posted by Dmmoore
            I used to practice a trim only landings in C-150's and C-172's. It works well with a 0 flap approach, speed 80 knots all the way to the runway. Fly it on at 100 - 200 FPM rate of descent, no flair, ground effect will cushion the touch down, throttle to idle, normal braking. Distance for the 150 is about 1500 feet. A little more for the 172.

            Refugee from ADC
            Interesting, Don, thanks. Throttle to idle just before touchdown or just after?

            Comment


            • #7
              Originally posted by Half Bottle
              Interesting, Don, thanks. Throttle to idle just before touchdown or just after?
              At touchdown.
              A little before and the nose will drop.
              A little after and you will balloon back into the air.
              Also, roll the trim forward as soon after touchdown as possible.

              We used to practice rudder and elevator trim only landings. Not as pretty but also possible to land (C-150, C-172, L-18 with no ailerons or primary elevator control.

              The Reeve L-188 did not have primary rudder control. The F/O operated the trim, Captain operated the elevator trim, S/O took care of what power plants they had operating.
              One of the best examples of CRM I've ever witnessed.
              Don
              Standard practice for managers around the world:
              Ready - Fire - Aim! DAMN! Missed again!

              Comment


              • #8
                This procedure is actually listed in the emergency section of the 172S POH.
                It says to trim for level flight at 65 knots with the flaps at 20 degrees, then not to touch the trim, using only power to control the glide. At the flare the nose may fall as a result of the reduction in power, so they say to apply full nose up trim before touchdown.
                Not that I'd necessarily want to try this, but it's better than them saying "oh well, you're pretty much f**ked.
                I wonder what you'd do in a T-tail.

                Comment


                • #9
                  Shouldn't the elevator be balanced? A balanced control surface should go to the aerodynamically faired position. In the aerodynamically faired position it does not provide control but will provide stability.

                  Comment


                  • #10
                    Originally posted by 474218
                    Shouldn't the elevator be balanced? A balanced control surface should go to the aerodynamically faired position. In the aerodynamically faired position it does not provide control but will provide stability.
                    A "BALANCED" flight control is balanced to prevent control surface flutter. The trim setting determines where it rides.

                    On and aircraft with stabilizer trim, the elevator always fairs with the stabilizer unless the pilot or auto flight system moves it.
                    Don
                    Standard practice for managers around the world:
                    Ready - Fire - Aim! DAMN! Missed again!

                    Comment


                    • #11
                      Don... going back to your emergency drills, is there any truth in the rumour that you can exercise directional 'control' of a C152 by coordinated use of the doors?

                      Comment


                      • #12
                        Originally posted by tds
                        Don... going back to your emergency drills, is there any truth in the rumour that you can exercise directional 'control' of a C152 by coordinated use of the doors?
                        You can. But I never gad the guts to try a landing using only the doors for directional control.
                        Don
                        Standard practice for managers around the world:
                        Ready - Fire - Aim! DAMN! Missed again!

                        Comment


                        • #13
                          Originally posted by Dmmoore
                          You can. But I never gad the guts to try a landing using only the doors for directional control.
                          Wow... so you could lose all primary flight control linkages, and still be able to attempt a controlled landing. Nice.

                          Comment


                          • #14
                            Originally posted by tds
                            Wow... so you could lose all primary flight control linkages, and still be able to attempt a controlled landing. Nice.
                            You had better be an octopus if you lost all primary flight controls.
                            Don
                            Standard practice for managers around the world:
                            Ready - Fire - Aim! DAMN! Missed again!

                            Comment


                            • #15
                              Originally posted by Dmmoore
                              You had better be an octopus if you lost all primary flight controls.
                              Yeah, I guess trim, engine controls and both doors on approach might be considered a 'high workload' situation for a solo pilot.

                              Good CRM exercise with two, maybe!

                              Comment

                              Working...
                              X