WhiteRook

My Feedback: (38)

does anyone have any pics of operating rudder trimtabs on warbirds ? i have afew ideas


thanks RCU

Dash7ATP

I can't understand why you would want them to operate. Typical trim tabs are to reduce or eliminate the force needed to maintain straight flight in cruise, and reduce or eliminate the right rudder required during takeoff and climb. Any forces produced by operating trim tabs will be fighting the rudder servo. Now, if you are talking about rudder servo boost tabs, that is another matter entirely. They are not necessarily positioned from the cockpit. The ones I'm familiar with have a push rod connected to the vertical Stab, and move only when the rudder deflects, and in the opposite direction. This provides a force helping the rudder deflection and reduces the pressure required of the pilot on a large surface that does not have hydraulic boost. This could allow you to use a much smaller servo than you might otherwise need on a large control surface. The Dash 7 I used to fly had these on the elevators, as the large rudder was hydraulic powered.Dash

WhiteRook

My Feedback: (38)

thats what i was thinking of using it for ,counteracting pull to the left, on takeoff

invertmast

My Feedback: (23)

There is this new invention called the rudder chAnnel that works wonders for that problem! Lol

Rudder trim or boost tabs arent going to help this issue as both still require an action by the pilot for them to function. Unfortunately for some, there is no other way to counteract a yaw tendency automatically except by either your own thumbs or by using a gyro.

Peter_OZ

My Feedback: (1)

when left thumb does not work install gyro. that is all!

wphilb

My Feedback: (10)

What I think you are looking for is an ability to input a set amount of rudder "trim" for take-off and climb, yet remove that from the cruise setting once cleaned up and in cruise configuration?

dadragon

I do giant scale warbirds and put trim tabs on all the moving surfices eccept the flaps what that dose is like making a rudder for a rudder it takes alot of strain off the servos.

vertical grimmace

My Feedback: (1)

Many full scale trim tabs are sheet metal (aluminum) that are bent on the ground because a pilot suggests they need to be bent. There is a difference between a boost tab, and a trim tab.
Now, I could see how a small trim tab could help keep your plane straight, and not strain a servo, but You will have to be pretty big for this to be the case. But by and large, I would see this as unnecessary.

dadragon

does a 150" AD SKYRAIDER count,Phil from the UK done it to a 180" skyraider they do work.its all on rc scale builders on 180" skyraider.I done it to my 150"

invertmast

My Feedback: (23)

Actually there is a difference between Just a trim tab, and Just a boost tab. But many times they are combined into the same unit.
Just a trim tab is either ground adjustable or pilot adjustable in flight. Its used to trim the airplane for hands off flight at a given speed, if its inflight adjustable, its deflection stays linear as the flight control it is attached to moves.
Just a boost tab (aka servo tab) is not adjustable period. It has a fixed length pushrod that is attached to a stationary point on the wing or stab, and then the "tab" on the flight control it is attached to is hinged. As the flight control is delfected, the tab moves in the opposite direction of the flight control surface. This opposite deflection helps "boost" the control by relieving the amount of force needed to move the flight control, this is especially useful at high speeds with mechanically actuated flight controls
There is also an Anti-servo tab that does the opposite of the boost tab.

Now a combines boost /trim tab just adds an adjustable actuator in place of the fixed point on the wing/ stab. This allows you to use the boost tab to adjust trim when the control surface ia at neutral and then when the surface is moved, it helps reduce the force needed to move the control surface.

vertical grimmace

My Feedback: (1)

Wasn't boost tab separation the cause of the "Galloping Ghost" crash at Reno?

invertmast

My Feedback: (23)

Yep,
it that scenario it was a boost and trim tab. Same surface with two jobs. When it came off, the nose down pitching moment it was providing was lost, which is what cause the pitch up