Question about rudder angles  
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Question about rudder angles - 5/15/2008 9:42:29 AM   
golf_lake



Posts: 76
Joined: 9/4/2002
From: Adelaide
Status: offline
Being new to this and trying to learn to fly on my own I have an annoying problem with my XP electrafun.

When turning it drops it nose and will go into a dive unless its turned really slow.

I have already moved the push rods for both the rudder and elevator to the most outside holes to reduce movement so I don’t over control it.

Looking at the rudder it slopes back at a fair angle, I cant help thinking that this angle is giving the tail end some lift as it turns.

Would cutting the tail fin so the rudder section is more upright, would this reduce this effect?

What other effects would this have?
       Post #: 1

RE: Question about rudder angles - 5/15/2008 12:40:11 PM   
LouW



Posts: 798
Joined: 1/1/2003
From: Moreland, GA, USA
Status: online 		My guess is that you are turning using rudder only. The action you describe is perfectly normal. The rudder causes the wing to bank, which causes the airplane to turn. However the wing is no longer lifting straight up but is tilted also. The amount of lift lifting upward is less so the airplane begins to descend.

The solution is to simply apply a little up elevator to increase lift on the wing during the turn. It may help to think of the rudder as the “bank” control and the elevator as the “turn” control.

(Changing the slope of the rudder would have very little effect either way.)

< Message edited by LouW -- 5/15/2008 12:42:12 PM >

(in reply to golf_lake)
       Post #: 2

RE: Question about rudder angles - 5/15/2008 12:44:08 PM   
wellss


 

Posts: 64
Joined: 6/14/2002
From: St. Catharines, ON, CANADA
Status: offline 		Not likely, if anything it would cause the nose to pitch up, right?

It could be gyroscopic effect of the prop. The faster it yaws, the more it will pitch. Depending on the direction of rotation of the propeller, it will be worse in one direction. Not much you can do about it, except what you've done and apply more elevator in the turn.

(in reply to golf_lake)
       Post #: 3

RE: Question about rudder angles - 5/15/2008 1:04:04 PM   
golf_lake



Posts: 76
Joined: 9/4/2002
From: Adelaide
Status: offline 		Thanks for the input

(in reply to wellss)
       Post #: 4

RE: Question about rudder angles - 5/15/2008 6:07:14 PM   
R8893


 

Posts: 382
Joined: 10/19/2002
From: Cincinnati, OH,
Status: offline 		Being nose heavy will also cause the nose to drop in a turn even with some up elevator input.

(in reply to golf_lake)
       Post #: 5

RE: Question about rudder angles - 5/15/2008 6:58:23 PM   
crasherboy


 

Posts: 98
Joined: 10/21/2006
From: Bryant Pond, ME, USA
Status: online 		Here is 2 cents. Being nose heavy could cause you some problems,aside from that I don't think rudder would have much to do with that. In a full scale airplane,one has to give it a certain amount of up elevator when making a turn .The steeper the turn [bank] the more up elevator you have to apply. The same goes for our models to. I training for a pilots licence they have you do what they call a 720 in which you do a very steep turn so as to keep your wing tip on a point on the ground[by sight that is]. Believe me it takes plenty of up elevator to keep the plane from falling off into a dive. Same thing as us modelers have to face. I have a full scale licence,but I won't be getting a medical anymore,so now I am stuck with the models. Do you have a computer radio where you could program in some up elevator in a turn? This would help you a lot if you could. If you don't then it is up to you to so it.

_____________________________

Do unto others as you would be done unto,well most of the time anyway!

(in reply to R8893)
       Post #: 6

RE: Question about rudder angles - 5/15/2008 7:24:00 PM   
Sport_Pilot



Posts: 7450
Joined: 1/21/2002
From: Acworth, GA, USA
Status: online 		Crusherboy is correct. You have to add up elevator in turns. Even with aeileron's. This is from the fact that a banked wing is creating its lift at an angle to the earth, this angle means part of the lift is now turning the aircraft, and there is less lift keeping it in the air. You have to add up elevator to add lift, this speeds up the turn as well as to keep it level.

(in reply to crasherboy)
       Post #: 7

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