Does the tailplane and elevator moves in the same direction?

[MR EL NINO]

My first post here.i got a question:
In an aircraft with a flying tail as the pilot moves the control column:

B.the tailplane moves and the elevator moves in the same direction

i think is the opposite direction ,because as the leading edge of tailplane moves down ,the aircraft will pich up .this is the same effect as elevator moves up. :ugh:

can someone help me please! Thanks in advance!

[Keith.Williams.]

You would not be using both an all-flying tailplane and elevator for pitch changes simultaneously.

But if we compare the effects of the two types of control surafce we could argue that they both operate in the same way.

Pulling the stick back will,

move the trailing edge of the elevator upwards so that the elevator is in a leading edge down attitude.

Or

move the trailing edge of the all-flying tailpane up so that the tailplane is in a leading edge down attitude.

[HotDog]

The horizontal stabilizer trim control system trims the airplane longitudinally by varying the horizontal stabilizer angle of attack and the elevators provide primary control of the airplane about its pitch axis. So, Pulling the stick back will, move the trailing edge of the elevator upwards so that the elevator is in a leading edge down attitude.

[BOAC]

El Nino - it is a difficult question to answer as there is no simple answer. Perhaps you can say where the question comes from? What was answer 'A'?

A 'flying tail' normally moves as one piece, with the elevators (if there are any) locked to the tailplane. In the event of a failure of what is moving the tailplane some aircraft can 'unlock' the elevators from the tailplane and then fly using just the tailplane. The control effect is as you state.

The 737, for example, however, uses ONLY the elevator for primary pitch control, and the tailplane is then 'trimmed' to a new position if necessary to trim the a/c.

Edit to add: there have been a/c where the elevator moves and the tailplane automatically follows, although I do not know of any like modern a/c like that.

[MR EL NINO]

Thank you L337! To BOAC：this is a ATPL exam question.

The full question is like this:

In an aircraft with a flying tail ,as the pilot moves the control column

A.the tailplane moves and the elevator moves in the opposite direction
B.the tailplane moves and the elevator moves in the same direction
C.the tailplane moves and the elevator is faired
D.the tailplane is faired and the elevator moves

I thought flying tail means a stabilator or a moveable stabiliser + elevator

just like you said:
The 737, for example, however, uses ONLY the elevator for primary pitch control, and the tailplane is then 'trimmed' to a new position if necessary to trim the a/c.


So the pilots primary means of controling the stabiliser is by use of the stab trim switches .

[Intruder]

I don't think it is a proper question...

First, few airliners have "flying tails"; the L-1011 is an exception I can think of.

Second, most airliners use a moving horizontal stabilizer for trim only, and elevators for pitch control via the control column/yoke. In that case, answer D is closest, but "faired" does not really describe the position of the horizontal stabilizer -- it is fixed in position by the trim mechanism.

Finally, there IS an airplane I know that is [somewhat] described by your question: IIRC, the Cessna Cardinal 177RG has a "flying tail" with an anti-servo tab that looks and behaves much like an elevator. That large tab moves in the same direction as the horizontal stabilizer when the control column is moved. That same tab also is adjusted by the trim wheel to re-center the neutral position of the horizontal stabilizer.

[BOAC]

God bless the examiners! In my book, a 'flying tail' has no elevator, but moves as a solid piece. I suspect the answer they want is 'C' but defer to others on this.

[RYR-738-JOCKEY]

Breaking it down, flying tail versus non-flying tail...the latter should be a fixed one, right...So assuming they're after what happens to a "moveable" tail when you use the elevator. Opposite action would be my answer, and more precisely, answer A.
Questions like this is not really testing anything else than your ability of analyzing the mind of the person behind it. :ugh:

[spannersatcx]

I think you need to go back and reread the question. As people have said on here a flying tail is a single item, like on the F4 Phantom (sorry it's the only one I know).

The answers are for an aircraft with a horizontal stabiliser with automatic stab trim etc, Like on the 747. Pilot pulls back the column elevator goes nose down, after a predetermined time (3secs off the top of my head) to off load the load to the pilot (and the structure) the stabiliser automatically trims nose down which reduces the elevator input (they fair as in answer C which is the correct answer) the a/c pitches up and the pilot can sit back and carry on drinking his coffee:eek:

If the A/P(s) is engaged and the pilot dials in a new altitude the initial reaction would be to move the elevators, again after a predetermined time the Auto Stab Trim will pick this up and trim out the elevator input by changing the stab position, again pilot goes back to drinking his coffee:eek:

Once the selected altitute is reached a similar thing happens to keep the a/c in straight and level flight (so the pilot doesn't spill his coffee:D).

[Mr.Brown]

As an engineer, we have loads of questions in our exams very similar, ie that sometimes you don't really know what they want from the question.
So my solution was to answer as best I could and enter on my rough work sheet everthing I knew about the systems in my own words (Sometimes diagrams) and submit it as a query.
A multiple choice template correction sheet doesn't do anyone justice so by having it written down as a query the examiner has to read what you've written and should give you credit for understanding the systems, theory etc.
Since Incorporating this method I've never failed an exam. I find it takes as long to write down all that as a query as it does to try and work out what they want from the question.

[TURIN]

Mr ElNino.
B. is the right answer IF the question is refering to (what I was always told was) an ALL FLYING TAIL. IE L1011 Tristar.
To clarify, have a look at the FIN and RUDDER set up on the DC10, 747SP and B777. They have vertical examples of ALL FLYING TAILS. Strictly speaking they are called DOUBLE ACTING but the gist is the same. For a given area and movement of a control surface, a double acting device is far more effective. The DC10 only had a small rudder as the no.2 engine was in the way, the 747SP needed a larger control effect as the moment arm was smaller (shorter fuselage). As for the B777, I think that required a partial double acting rudder to help in the event of an engine failure at take off power.
As others have said, A FLYING TAIL has no elevator. F4 Phantom is the classic example.
The other devices described by various others here, are standard TRIMMABLE HORIZONTAL STABILISERS. EG B747 A330 etc.
I may be wrong and will take any correction on the chin like a good egg. :ok:

[barit1]

Mr.Brown has a most excellent response to poorly written exam questions. The risk, of course, is that the examiner may fear you know more than he, and thus seek to eliminate you in the interest of job security. :ugh:

There is a prior thread named Stoopid questions (http://www.pprune.org/forums/showthread.php?t=277026\) about this issue.

[john_tullamarine]

Points of order, folk ..

(a) this forum is not just for those with a gazillion hours, engineering experts, etc, etc ....

(b) if a new chum asks a simple tech-related question it stays and, hopefully, gets answered appropriately, even if that answer is a link to an existing thread. It is a reasonable presumption that, for every question asked, there probably were several other posters who didn't ask the question for whatever reason .. In any case, our view is that the only dumb questions are those which don't get asked ...

(c) if a poster appears to have some difficulty with English then we extend him/her the courtesy of making that little bit of effort which may be necessary to accommodate the difficulty.

(d) the posts deleted are not pertinent to the basic thread.

[glhcarl]

The L-1011 uses a flying horizontal stabilizer with geared elevators. The entire horivontal stabilizer moves providing both primary and trim, pitch control. The geared elevators move at a constant rate with the horizontal stabilizer. When the nose of the horizontal stabilizer is full up (+1 degree) the elevators are faired, when the horivontal is fully down (-14 degrees) the elevators are up 24 degrees. The geared elevators provide addtional lift at lower speeds.

[BOAC]

El Nino - in view of the confusion over what they are after, I would recommend you look through the APPROVED syllabus to see EXACTLY what THEY mean by a 'Flying Tail'. It should be defined somewhere.

[GearDown&Locked]

Question: Is the Fokker 70/100 an example of a flying tail?

What wiki (http://en.wikipedia.org/wiki/Tailplane) has to say:
Supersonic aircraft now have all-moving tailplanes to counteract the Mach tuck when breaking the sound barrier and maintain maneuverability above the speed of sound. While technically called a stabilator, this configuration is often referred to as an "all-moving" or "all-flying" tailplane.

[glhcarl]

The Fokker 100 like every other modern commerical airliner, except the L-1011, uses the horiziontal stabilizer for trim and elevators for primary pitch control. So, no, the Fokker 100 does not have a flying tail.

[411A]

New pilots on the L1011 seemed to go through a learning cycle...at first they didn't like it, mainly because with DLC, the 'Boeing push' positively would not work, and also they expected that the all-flying horizontal stab should be reserved for jet fighters, and not a commercial transport.
Then after awhile, many began to appreciate the rather good engineering that went into the design (especially, of course, the automatic approach/land function) and would 'put up' with DLC, notwithstanding the fact that a few would switch it off, thereby hoping to once again achieve the Boeing push.
Opps! Didn't work so good after all, besides which, many First Officers would say to the Captain...ah, nothing in the book about switching off anything (except for a malfunction, of course) and these F/O's were absolutely positively correct.
NB. In many cases it was the first time...ever.:}

[HotDog]

Used to upset me when new pilots on the L1011 forgot they were on the Tristar and vigorously pushed and pulled the control column full throw, during pre-flight control checks. It literally shook the tail of the aircraft.:(

[glhcarl]

HotDog,

The following is from the Nov/Dec 1973 L-1011 TriStar Service Digest:

"Occasionally during ground operations of the L-1011, airframe viberations, thumpings or fuselage oscillations may occur which could cause cause concern to your flight crews, leading to possible delays until the cause has been determined. These conditions can be caused by two operational situtions as noted below:

1. Impingment of exhaust turblance:

During static engine run-up at N1 greated than 60% in certin cross wind conditions, the exhaust from the up-wind wing engine may impinge on the stabilizer and the resulting turbulences my generate a buffeting.

2. Moving the Stabilizer abruptly on the ground:

A. Rapid movement of the control column. The resultiing sudden acceleration of the large stabilizer mass may initiate a vertical oscillation of the fuselage.

B. The gain characteristic of the stabilizer servo input linkage is such that for a control column input motion, the stabilizer moves eight times as far/fast at the -14 degree leading edge down position (AC nose up) as at the +1 degree leading edge up position (AC nose down). This relationship allows for generation of an oscillation (similar to "A" above) at an approximate rate of 5 CPS.

These occasional vibrations/oscillations occue only on the ground; they are now a known peculiarity and should not cause concern once it has been determined that one of the above conditions induced the vibration. These conditions do not affect normal aircraft operation"

[411A]

There was one new TriStar operator who had their crews trained on the aeroplane who had previously had flown the DC-8.

Some of the results were quite surprising...then again perhaps not:ugh:

Preflight control checks, for example...with no hydraulic power.
A few would wrestle with the column, pushing and pulling with no decernable result, except to illuminate the aileron cross-hatch switchlights....whereupon they then could not extinguish same, even with hydraulic power now supplied.

What can you say to folks that can't be bothered to RTFB?:(:ugh: