Mixing a split elevator???

[omega blood]

What pros and cons would there be to mixing in and or coupling a split elevator on a convetional plane such as a mustang. i.e. right ailaron up, right elevator down and left ailaron down and left elevator up will give an increased roll rate. what other benifits or problems might there be with this set up.

[Ollie]

The elevator and aileron on the same side of the aircraft have to move in the same direction to increase the roll rate. The increase in roll rate will not be large because the elevator has less area than the aileron and the elevator has a much shorter moment arm to the center line than the aileron, giving it much less leverage.

[rcav8r2]

WEll not sure of the theory, but in practice they actually were worse. My buddy has a Morris Hobbies Big Boy with independant elevator servos for each half. I showed him how to set up his super 8 for this on a switch. ( both moving in the same direction) It actually rolls better without the elevators coupled to the ailerons. At slower speeds it is really bad. We're talking huge control surfaces with 45 degrees of throw , so that may play a part...not sure, but what Ollie siad makes sense.

It does make a great conversation piece when he is checking his controls on the ground though :D

[Ollie]

With 45 degrees of elevator throw the elevators act as air brakes, reducing the airspeed. All control surface effectiveness is proportional to the square of the airspeed. My guess is that the reduced airspeed reduced the roll rate enough to overcome the elevators' contribution to roll and then some. In this case, too much throw in the elevators is the problem. Try reducing the elevator throw to about 15 degrees or less and you may be able to see a slight increase in roll rate. The difference in roll rate will be small and easiest to detect at very, very slow roll rates. This probably isn't the effect you are looking for.

Maybe the reason some people use elevator coupling to ailerons is to enhance roll control while hanging on the prop. In this case, the ailerons are mostly outside the prop wash and the elevators are in the prop wash. With nearly zero airspeed over the ailerons they will have virtually no roll control but the speed of the propwash over the elevators will give some roll control effectivness.

[omega blood]

So in other words it may look cool but realy of no use.
Too bad....

BTW Ollie I just noticed you live in "Fat point" (transilated) I heard of some odd names this has got to be one of the odder ones. :)

As always thanks for the help.

[Ollie]

Hey O B,

If you think the name of the place is odd, you should meet some of the residents.

What has the last letter of the greek alphabet to do with blood?

[omega blood]

Originally posted by Ollie
Hey O B,
What has the last letter of the greek alphabet to do with blood?

Nothing realy. I just thought it would sound cool. It came about when I was watching a Japanese sci-fi cartoon. There was a wacked out guy who was given a ship called " The Blood". I said Hummmm. How about the Omega bood. And so it's been stuck in my head ever since.