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Fly Better With the Rudder
Cheating the legal way
Text, photos and video by Tom Hintz
Flight video – Done in RealFlight 7.5
Posted - 2-15-2015
When I was learning to fly RC planes my primary instructor was a fellow named Matt who had a simple approach to RC flying - Use ALL of the control surfaces. Matt told me once that he was going to teach me how to cheat at fun fly’s the legal way. He drilled me on using the rudder in all phases of flying from day one of his instruction and to this day, even after laying off of RC flying for 25 years, I use the rudder all of the time, mostly without thinking about it.
It amazes me how so many RC pilots do not use the rudder for anything but on the ground control during take offs and landings. Some use radio programmed rudder mixing, usually linked to the ailerons. I don’t like that because mixing adds that specific amount of rudder every time you use the ailerons regardless of the situation. To get the most from the rudder I think we must learn to apply it manually so we can “give it what it needs”, probably the most profound Matt-ism relating to learning to fly RC planes. Educate your rudder finger and your plane flies smoother with better control, both of which are safer for the plane and the people around it. Way back when simply using the rudder allowed Matt and I to win way too many fun fly’s.
Before anyone runs out to the field and starts banging the rudder stick around we have to remember that not all rudders are created the same. Where 3D rudders are designed to have tremendous impacts on that type of plane scale aircraft rudders are designed purely to assist normal flying.
Then there is coupling, a tendency of a model to nose down or up when rudder deflection is applied. Coupling is most often dependent on the amount of rudder deflection. With just a few degrees of rudder you might not see any up or down attitude change. Increasing rudder input and it can have a more pronounced effect on the plane. He again some people use mixing to counter the effects of coupling but I would rather do that manually. In response to winds and other influences the amount of coupling can change but the mixing is always the same where an educated rudder finger can “give it only what it needs”.
Another result of too much rudder is the plane wanting to roll. When a plane is in a yaw the leading wing generates more lift so that wing wants to go up, pushing the opposite wing down. Some planes can literally snap roll when too much rudder is applied. There is no set amount of rudder that will induce the roll (or worse) but rather that is dependent on the type of plane and other variables. I take a new plane up two or three mistakes high and try various amounts of rudder input to see what happens. Once you know how the plane responds to different amounts of rudder input it is easy to avoid that situation.
When I fly a new or old plane for someone I like to take it up to a safe altitude, (two mistakes high) so I can experiment with rudder input to see if the plane has coupling or other bad habits related to rudder deflection. This also allows me to try the rudder amounts in both left and right applications. The reaction to rudder can be totally different to one side vs the other.
Coming, Going and Inverted
I find it much easier to remember which way to go with the rudder stick by picturing pushing on a part of the plane with the rudder stick. For example when my plane is coming towards me, right side up I “push” the tail with the rudder. That lets me induce the yaw I need to adjust the planes path where I want it.
Probably the scariest situation to many in terms of rudder use is when the plane is inverted and coming at you. I just “push on the nose of the plane” with the rudder stick to make corrections. Very easy to remember and very effective with most planes. As always give the plane only what it needs. A little rudder is always better than a bunch for course corrections. Some planes are more sensitive to rudder input while inverted so this is another thing to experiment with three mistakes high.
Flying the Tail
Some planes such as the uber-popular Piper Cubs have a tendency to drag the tail towards the inside of a turn. To correct this we, like the full scale pilots, use a bit of rudder to swing the tail upwards so the fuselage is flying level through the turn. You may find other planes with this same tendency to some extent and they will also benefit from a just a bit of rudder.
Cross Wind Landings
Because RC pilots seldom have multiple runway options we are forced to land from the left or right even when the wind is directly in our face or on or back. Here again, sparing use of the rudder can turn a challenging (and dangerous to the plane) flying situation into just another simple maneuver. Remember the visualizations, coming at us, right side up we push on the tail with the rudder stick.
As the plane approaches the runway in a cross wind the tail will “weather vane” if the wind is strong enough. That means that the plane will pivot its nose toward the direction from which the wind is coming. If you know how to use the rudder all you have to do is keep the wings level and adjust the throttle to keep the plane coming, sideways and all. When you get to the end of the runway and want to set the plane down “push on the tail” with just a little rudder and hold it. You will find how much rudder is needed to rotate the plane so it is straight with the runway. As the plane sets down, release the rudder and begin steering the plane on the ground as necessary. On some fields it is best to approach the runway on a diagonal and then use the rudder to turn the plane so it is aligned with the runway centerline.
This really is an easy thing to learn if you avoid stabbing the rudder stick. Most planes will need a very small amount of rudder to get straight with the runway. One again Matt’s “give it what it needs” technique lets you land nicely in a surprising range of wind conditions.
There are lots of situations that make it better to use less banking of the wings and more rudder to turn. The plane is nearly always more stable with the wing flatter to the ground and that gets even more important when we are already low to the ground such as on landing approaches.
Here again a small amount of rudder held through the turn is usually all that is needed. Most planes will need a bit of counter aileron (cross control) to keep the wing flat. Practice adding just enough counter aileron to keep the wing level. When the plane turns to the direction you want back off of the rudder and aileron to continue flying, landing or whatever you wanted to do.
Practice, Practice, Practice
Like anything in RC flying, practice makes you better. Once you start using rudder effectively you will wonder how you flew without it. I recently flew a high speed delta wing plane that used elevons and no rudder. During the early flights I was having lots of trouble turning the delta cleanly before I realized that I was trying to use the rudder the plane did not have. Rudder does get to be an automatic thing if you use it enough. The key for normal flying is to use as much of it as is needed and no more. In aerobatics the rudder is also crucial but then we generally use major doses because of its powerful influence on flight. Your job is to decide how much is right for what you are trying to do.
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