"Balanced" Controls

[Pips 5]

In reading about the design of aeroplanes in WWI I often come across the terms 'balanced' and 'unbalanced' controls. It can be referring to the aileron, rudder or elevator, but seldom all three on the same aeroplane. And as often as not the number and type of aeroplane's that have a 'balanced' control are exceeded by those that do not.

 

What is a 'balanced' control? And what effect does it have on the flying characteristics of said aeroplane? If the effect is positive, why were not all aeroplanes fitted with 'balanced' controls?

[Tamper 9]

Not normally an area I claim to know a lot about, but I'd like to take a stab: I think they're talking about having part of the control surface that actually sticks out in the opposite direction as the majority of the control surface. So, for instance, the Fokker Dr1 and DVII had ailerons that had tabs that, while the aileron went down, the tab area went up and vice versa. I think on the Dr1 it was referred to as "horn balanced", although I have no idea why.

 

In my mind, the theory is that you're less likely to over-control if you have at least some counter force working against the pull of a control surface. The more you move the control surface, the more effect this 'counter-balance' comes into play. I think the idea is it tends to 'smooth' the control surface response and operation. Plus, re-centering is easier because of the opposite effect provided by the tab. It is important to note that the area of the 'balance' tabs is much less - maybe only 5-10% (?) of the area of the actual control surface, otherwise (to me) it seems it would completely offset the effect of the control surface.

 

Or at least that's what I thought about it, anyway *lol* I think there are probably better explanations, maybe even some pics, online somewhere.

 

As to why it's not on all airplanes, I suppose I would say that what is "better" (or "positive" as you put it) is generally a matter of subjective opinion. I might say that power steering is better because it's easier for me to control a turn; you might say it's better without power steering because of the tactile feedback and 'road feel' you get.

 

Interesting question, for sure.

 

EDIT *LMAO* and I guess I got it just about completely WRONG!!! I just read up on where the idea is to *assist* the pilot in moving the control surface. In retrospect, it makes sense: The tab ("horn") sticking out will actually help push the other part of the control surface *against* the forces acting on it. It's done for the most part by hinging the conrol surface at some point behind it's leading edge (look at the Dr1 and DVII ailerons, you can see how this is possible, which is why I call them 'tabs".

 

Learn something new every day

Edited April 12, 2012 by Tamper

[Olham 164]

This article seems to explain what you want to know, Pips:

 

http://www.allstar.fiu.edu/aero/axes32.htm

[Hauksbee 103]

Your edit has it right, Tamper...at least, as I understand the concept. The 'tab' makes the controls lighter, requires less muscle from the pilot.

Edited April 12, 2012 by Hauksbee

[Pips 5]

Cheers guys!