Hi I would like to know if using a y to tie in rudder and alerions woud have any effect on landing or take off.or would it help ?

I would think it would prevent both.

Do not Y two different controls into one channel.

When we mix two controls, it is done in very small amounts to correct for knife edge flight, is one example. On a Y harness is would be 1 to 1 and that may equal the total flight time of your bird if you did that.

Why would you want to anyway????

agreed with ynot..... this would be bad....

I would think.....

as mentioned, using a computer radio to mix in 10 ro 20% would be good.....

but putting two things that "seem" similar but are really VERY different would make the plane darn near unflyable

It was commonly done in the mid 60's when a lot of the proportional radios only had three channels. Back then it was refered to as "CAR" which stood for Coupled Aileron and Rudder. But if your radio can do it, it is better to mix them together so that the rudder is independent and when you give aileron, it mixes with the rudder for better turns. Depending on your airplane, if you want to tie the two together with a "Y" harness, I would keep full aileron travel with about 1/2 rudder. In the air, this will have the effect of speeding up the rolling rate.

I also agree with YNOT,

Doing this with a Y cable would be bad. If you are looking at having the rudder move with the aileron you can use a computer radio to mix a small percentage of rudder to the ailerons. Cubs need this to fly the best and it is called coordinating your turn

To be really honest here. You should learn to coordinate your turns before mixing it in with the radio. Learning when and how to use the rudder is a good thing and will help to make you a better pilot and you will soon see that mixing for coordinated turns is a moot point

Now for Knife Edge flight, mixing rudder to elevator to mix out a pitch change is good because it can help take some of the load off the pilot, especially on a biplane where you almost always need to mix rudder to elevator and rudder to ailerons.

I am not putting down mixing, I am justr recommending that before you setup the mixes you learn a little more about ALL of the planes control surfaces.

I agree with the the above posts. If you can avoid it, better to have separate channels. That being said, I believe you could get by with it on certain airframes that have high dehedral and have a the rudder move a small amount compared to the ailerons. If I was a newbie, I'd stick to separate channels though.

Thanks guys I am very glad I asked you have more then helped me out.