Knife Rudder Issues
 

When I give my Knife arf rudder she immediately noses down and in the direction I give the rudder. My little Gee Bee arf when given rudder will flat turn in the direction I give rudder (I'm assuming this is what you want the plane to do).
How can I get the Knife to act right? What causes it to want to do that?

Knife Rudder Issues
 

Just the design of the airplane Billy. Mine does that too. I need to mix in some up ele. on my 8U when I add rudder.

I don't like the pitching down but what can you do? :disappoin

Tom...

Knife Rudder Issues
 

Agreed,

The Knife has SO MUCH rudder authority and short coupling that you get some adverse effects when you apply much rudder. I had to mix in some elevator and opposite-aileron to help flatten mine out and it is still hard to hold a knife-edge without snapping out or doing an unintentional knife-edge-loop.

Neo

mixing
 

when mixing in some elevator with the rudder doesn't that affect the hovering maneuver ?

Knife Rudder Issues
 

Not adversely. First off, you're mixing an ever so slight amount. For example, at 100% rudder throw, you might get only 8% elevator compensation. You will almost never be giving it 100% rudder in a hover, and if you do, it will need the compensation to keep from pushing over onto it's belly.

The usual 20-40% throw you might give in a hover would result in only 1.6 to 3.2% elevator... almost nothing. Again that slight amount would still theoretically be needed anyway since you are pushing lot's of prop wash across your rudder in the hover manuever and it will still have coupling that needs corrected.

At higher speeds and more throws, like in knife-edge... the full 8 to 10% has a greater effect than in the stationary, low-throw hover scenario.

Neo

Knife Rudder Issues
 

That's what I was looking for. Now I'll go find a link on how to get the rudder and ele to work at the same time. I feel very confident in my 8UHFS skills but I haven't tried this yet.

Knife Rudder Issues
 

Billy,
Just set up a Programable mix to activate elev with rudder input.

Using the mix in a hover?..........
Look at it this way, if the nose drops with rudder in level flight its also going to pitch to the belly in any other position. The plane doesnt know if its inverted or upright. If the mix is needed in one atitude it will most likely be needed in other atitudes as well.

Knife Rudder Issues
 

Wayne - Do you do allot of mixing on your profiles to clean up the bad tendancies?

Knife Rudder Issues
 

Thanks for the heads up Billy.

And Thanks to NEO and wgeffon for the input.

I'm going to have to try this as well on my Knife.

Knife Rudder Issues
 

Paul,

I have in the past but, I find that with the extreme amount of control throws most people (including me) use mixing doesnt really help.

These are fun-fly planes not pattern planes. They arent suppsed to fly with a ton of precision.

Knife Rudder Issues
 

Tork It or Dork It!

It's a profile... :D

Pleased
 

I like everybody's input in this thread. Like Wayne said, the airplane doesn't know what attitude it is in so if a little elevator and opposite aileron is needed to counteract pitching and adverse roll when the rudder is slammed, add it with a programmable mix.

Billy, your 8U is fully capable. That is the transmitter I am using at this time. On my UltraStick 60 I have all 5 Pmixes in operation in one way or another.

Don Edberg's Book, Programming Futaba's 8U is great, I got mine from Don at http://www.flash.net/~dynamic3/don.html

Tom...