What Bf.109K4 do we have anyway?

[MiloMorai]

Originally posted by Charge
"Guess you have not had the pleasure of applying rudder for any amount of time above the cruise speed the trim tab on the rudder was adjusted for.
There must be some truth to the story 109s pilots had one leg fatter than the other for Mtt to have a rudder Flettner on the 109."

It is true that above or below the set speed of trim tab you had to constantly apply pressure on rudder to keep the plane flying straight. So why not just install a simple trim tab adjustable from cpit but to change totally the more complex control system is beyond my reasoning. Also if the rudder becomes too light in slow speeds there's always a risk of over controlling, and even more so if the controls and not balanced enough.

I don't recall reading about the differences pilots experienced when changing to K. So were they indeed locked?

The method of flettners require the only to control of the tab, and the tab movement moves the rudder surface. So if the tab is locked the control wires need to be switched to rudder.

-C+

The Flettner is more complex????



Charge, do you know how the Flettner worked? One can't get much more simpler and is certainly more simpler than running another set of cables from the cockpit with pulleys and a wheel.

The Flettner tab certainly does not move the rudder. The movement of the rudder causes the tab to move.

[Charge]

Quoting myself: "This device, which was invented by Anton Flettner, xxxxxx, consisted of a small tab mounted at or behind the trailing edge of the main control surface. The pilot's control was connected just to the tab. When the tab was deflected, it moved the main control surface in the opposite direction."

http://history.nasa.gov/monograph12/ch6.htm

So if the tab is locked as Kev suggested the rudder cannot move at all. That is unless the Flettner arrangement in K differs from the original idea of Mr Flettner.
I don't know if it does. Never really noticed the whole thing.

-C+

[Krusty]

It doesn't work that way, from everything I've seen and read. The small area of the fletner isn't going to move the large rudder way out into the airstream. The fletner just acts to relieve pressure by catching airflow off the trailing edge and giving it an extra "push"

The fletner is locked in relation to the fuselage. The rudder was still controlled with the usual cables.

[MiloMorai]

Charge, here is a crude diagram on how the Flettner worked.



A-D and A-D' is the rudder. The blue is the Flettner tab.

Point A is the rudder hinge line and Points D/D' is the tab hinge line.

Line A-B is fixed to the fin. Line C-D is fixed to the tab.

The rectangle A-B-C-D becomes a parallelogram A-B-C'-D' when the pilot inputs some rudder.

[gripen]

The balancing tab system seen in the tall tail (and rarely in ailerons) of the Bf 109G and K is usually called as geared tab in anglo-american litterature.

[Angus]

And today, in the smaller aircraft (as well as bigger?) we use.....CABLES AND WHEEL