• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Elevons not effecting yaw

ralley

New member
#1
Hi all, new guy getting back in to flying after years away. I used to fly scratch built control line as a kid. Getting back in to it with the FT Pizza Wing desing built out of foam (cardboard came out too heavy). My setup seems a bit lacking in power but my biggest issue seems to be my elevons aren't giving me any change in yaw. They roll me nicely but no change in heading. I'm going to try a new air frame with smaller winglets but though I'd ask if anyone has any other suggestions?

Cheers, Rob.
 

evranch

Well-known member
#2
Welcome back to the hobby!

Elevons don't affect yaw, which is why elevon planes are often referred to as "bank and yank" control. Set in your bank angle, then pull up on your stick to perform the turn. It's working as expected.

You've done a good job building your wing if it doesn't turn at all when you roll it, that means your wing is almost perfectly flat and your elevon throws are perfectly balanced.
 

quorneng

Well-known member
#4
In a flying wing or even a delta "bank and yank" is even more important than in a conventional layout plane particularly if there is a lack of rearward fin area.
Remember in a bank and yank turn the major aileron input is only used to create the bank but once it is set the ailerons are just used as a 'trim' to maintain the bank angle. The rate of turn is controlled by the elevator. The only major aileron input is to level off again.

Also don't forget the effect of adverse aileron yaw - more drag from the down aileron than the up. This tends to make the plane want to yaw in the opposite direction to the intended turn.

Big aileron input at a slow air speed is a sure way to initiate a spin or spiral dive. How many have discovered this effect on the final turn before landing. ;)
 

Merv

Well-known member
#5
I agree with @evranch, you need to bank & yank.

FYI. Sometimes ailerons can cause adverse yaw. That is banking to the right will cause the plane to yaw left. One cause of this is the down aileron going down more than the up aileron goes up. The down aileron cause too much drag and yaws the plane the wrong way.
 
#6
A tip on elevons- Ever since building the Arwing, which had only elevons and the elevons had about 35 degrees of anhedral, I always liked anhedral elevons because they have converse yaw, making turns feel very crisp and snappy. That was one of my earlier custom designs and I feel I should revisit it.
 

ralley

New member
#7
A tip on elevons- Ever since building the Arwing, which had only elevons and the elevons had about 35 degrees of anhedral, I always liked anhedral elevons because they have converse yaw, making turns feel very crisp and snappy. That was one of my earlier custom designs and I feel I should revisit it.
That sounds interesting, do you have a link to plans for your Arwing design?