Variable Incidence Tailplane
Join Date: Sep 2002
Location: La Belle Province
Posts: 2,179
Likes: 0
Received 0 Likes
on
0 Posts
Sounds like its referring to any tailplane that moves, whether for trim (civil types usually) or pirmary flight control (military types). "all flying tail" is another term.
Only smaller, slower aircraft tend not to have some kind of h stab movement (in general; exceptions exist of course, including planes that don't have them at all)
Only smaller, slower aircraft tend not to have some kind of h stab movement (in general; exceptions exist of course, including planes that don't have them at all)
Join Date: Jul 2001
Location: Auckland NZ
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
As I understand, the VI Tailplane , or stabilizer is as used on most or all large aircraft. Due to the wide speed envelope, and varying weights, they are primarily designed to negate the need to drag the elevator around with large trim tab deviations. The VIT moves as a whole foil, and provides the trim requirements as commanded by the flightdeck on the yoke, or trim wheel. If you look at a modern jet, you will see the movement allowed with the stabilzer at the leading edge root next to the aircraft, as a patch often with graduations, but almost always as a different colour or shaded area.
Under autopilot, the VIT will be used at some flight modes rather than the elevator, and due to the power of this, can cause nasty problems when disconnecting AP in a hurry as elevator loads can be very heavy whilst trying to 'fly the trim out' until the trim is returned.
The 'Flying Tail' is a system of full integration with the stabilizer being used both for trim and aircraft pitch changes in both manual and autoflight. A rather more refined version of the Piper Indians stabilator.
I think I've got them the right way round!
Under autopilot, the VIT will be used at some flight modes rather than the elevator, and due to the power of this, can cause nasty problems when disconnecting AP in a hurry as elevator loads can be very heavy whilst trying to 'fly the trim out' until the trim is returned.
The 'Flying Tail' is a system of full integration with the stabilizer being used both for trim and aircraft pitch changes in both manual and autoflight. A rather more refined version of the Piper Indians stabilator.
I think I've got them the right way round!
There are numerous variations on the theme. Generally the goal is drag reduction although it can also be simplicity, weight, cost etc. Some variations can be:
1. Piper Warrior: The whole surface moves to provide pitch control. A separate tab is used to negate the tendency to move to full deflection under aerodynamic loads AND to provide trim.
2. F111: Whole surface moves but is hydraulically powered removing the need for an anti-servo tab.
3. Piper cub (I think it's the Cub?), many jet airliners: An elevator hinged off the the tailplane however the tailplane incidence is adjustable to provide trim.
4. Mooney: An elevator is hinged off the tailplane. The tailplane incidence is fixed WRT the empenage however the whole empenage pivots. This has the same effect as the Piper Cub's method.
1. Piper Warrior: The whole surface moves to provide pitch control. A separate tab is used to negate the tendency to move to full deflection under aerodynamic loads AND to provide trim.
2. F111: Whole surface moves but is hydraulically powered removing the need for an anti-servo tab.
3. Piper cub (I think it's the Cub?), many jet airliners: An elevator hinged off the the tailplane however the tailplane incidence is adjustable to provide trim.
4. Mooney: An elevator is hinged off the tailplane. The tailplane incidence is fixed WRT the empenage however the whole empenage pivots. This has the same effect as the Piper Cub's method.
Last edited by Tinstaafl; 8th Jun 2003 at 08:15.
Join Date: Sep 2002
Location: Desert
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
I'm not sure if its the same thing, but the DHC4 Caribou's tailplane will change angle dependant on the flap selection. The more flap that is deployed, the further the nose wants to drop, so the incidence on the tail plane increases to try and keep it directly in the airflow. It only changes about 6 degrees or so I think!
