Qwain Glyndwr,
Thanks for your quick answers. On my way out, I will make some quick clarifications, and perhaps have some more quick questions.
Originally Posted by
Owain Glyndwr
airtren
The elevators are full span and the hinge line is at 70% chord, so the elevator area is 30% of the exposed HS area
So, the Elevator to THS surface ratio is 3:7, which is 1: 2.33. .... ...
I know this has been said, but I think it is based on a misinterpretation of the facts (as is quite a lot said here
)
I like that...
.... I rather suspect people have been thinking of the ability of the elevator to overcome the THS when they are in opposition, but since the THS is slaved to the elevator it is difficult to see how this could in any way be relevant particularly when you consider the main thrust of my arguments on THS behaviour
Or the THS overcoming the Elevators....
Your focus on THS alone is fine. The THS is slaved to the Elevator - I take that in terms of Auto-trim, as the Elevators move first, and then the THS move follows.
But in terms of rotation and angle, I take that the Elevator is slave to the THS, in that it is hinged to the THS.
As the Elevator is hinged onto the THS, if the THS were FIX, its move/angle would be "simple".
But as the THS moves itself, the Elevators move/angle is relative to the THS, and absolute to the a/c body, and thus "complex" - it has two components: its own, and that of the THS.
At this quick writing I am not sure if I am clear.
As the pitching momentum depends on the angle, the complex angle has a complex effect on the pitching momentum.
Originally Posted by
Owain Glyndwr
So far as I can see, never.
Are you sure?
I am not.... but will have to come back to this later....
Originally Posted by
Owain Glyndwr
To give a NU moment the THS would have to experience a negative AOA. ....
Imagine cruise AoA, and THS and Elevators at corresponding position.
What would Manual Trim NU of THS do?
Originally Posted by
Owain Glyndwr
To be honest I am not sure what you are asking here.
Let's ignore it for now, as it is included in the rest, and I may have mistyped...
Originally Posted by
Owain Glyndwr
Elevator deflection is always quoted relative to the THS chordline.
For the rest it is probably easiest just to give the numbers:
Maximum NU deflection relative to body axis is (14+30) = 44 deg
Maximum ND deflection relative to body axis is (2+15) = 17 deg.
Yes, it's easiest I agree, ... but it is so, because it is a "simplification".
It considers only:
max NU, with both THS and Elevators at max NU, and
max ND with both THS and Elevators at max ND,
and leaves out the other two combinations, which are part of the set of possible positions see my original post bellow:
Originally Posted by airtren
Elevators max NU (absolute) angle is at
- maximum at THSmax NU
- minimum at THSmax ND
and
b) the Elevators max ND (absolute) angle is
- minimum at THS max NU,
and
- maximum at THS max ND.
Originally Posted by
Owain Glyndwr
Originally Posted by airtren
Originally Posted by Qwain Glyndwr
The nose was being held up by the application of elevator.
5. At AoA 40 degrees, are the THS + Elevator, Thrust, (and Cg) the only (force) factors contributing to the pitching momentum?
It is usual to take moments around the CG, so that doesn't figure in the calculation of moments except through variations in the relevant moment arms. The pitching moment is then affected by THS+elevator, Thrust and pitch rate, although this last is a minor term compared to the others.
I am not sure how to read, or connect your answer to my question.
So, I will rephrase.... each participant moment is a force and an arm. .. I added the Thrust, and Cg in my question to explicitly refer to them, although you've implicitly included them in your sentence I think, or if I understand correctly.
question:
are there any other forces (with their respective arms) involved? at that AoA?
Sorry, for the speed I am typing it,... the temperature of the seat, reminds me I was supposed to leave it a while ago,
Thanks.