May be a question raised before, but I am quite new to this wonderful hobby , I hope someone is willing to help.

Always read from the thread about coordinated turn helps to make the plane a smoother turn, I just don't know what is it, and how to make it work.

I am flying a Pheonix Classic 40 glow trainer with Tower 46 engine and Futaba T6XH computer radio. Thanks in advanced for your patience and help.

Some planes need rudder input to make a smooth, on-track turn. When turning, a plane can follow the nose, or the tail can skid to one side or another, usually to the inside of the turn. This is also called "adverse yaw" and can be caused my the "down" aileron having more drag than the "up". Use the rudder in the direction of the turn to bring the tail more in line with the nose. It usually doesn't take much. Practice with it until your plane is making on-track turns.

Dr.1

All planes need rudder to do a coordinated turn. Once you get used to seeing what coordinated turns look like, the lazy rudder turns that most RC flyers do become obvious and look so wrong.
The amount of rudder needed for a coordinated turn depends on the bank angle. A 90 degree bank is all elevator. A 45 degree bank is half elevator and half rudder. A 30 degree bank is 86% rudder and 50% elevator.
I use the ailerons to set the bank angle and then I use a mix of elevator and rudder to carve the turn. The ailerons should be neutral during the turn. If you have to hold ailerons to stay banked, you are not using enough rudder. If you have to hold opposite ailerons to keep the bank from increasing, you are using too much rudder.

A lot of people will probably chime in saying "forget the rudder, the plane will turn just fine without it" and they are absolutely right, an un-coordinated turn won't make the sky fall but once you get used to seeing a coordinated turn, you will not settle for anything less, not to mention that it will gain you a lot of points for scale flying realism if you compete in scale flying contests.

If you have a computer radio, you can mix some rudder in with your ailerons to accomplish coordinated turns.

If you fly on an airliner take a look at your drink during a turn. You will notice that the fluid level stays parallel with the floor of the airplane during a turn. This is the sign of a coordinated turn. Modelers try to achieve this by inputting some rudder during turns. Form the ground it is very difficult to tell how much rudder is enough - they are really just making a wild guess as to how much and when to add rudder.

Nice description of making the turn, but I'd like to modify it a bit. Whether you have to maintain aileron input in the bank depends somewhat on how much dihedral is in the wing; more dihedral will tend to bring the plane out of the bank, so you might have to hold a little aileron through the turn to maintain the amount of bank you want. And note that B.L.E. mentioned elevator input; this is to maintain altitude through the turn. If you just use aileron and rudder, you'll lose altitude in the turn. How much you need will depend on the plane, some have more "pitch coupling" with rudder input than others, requiring more elevator input to counter it.

Now you can see what "coordinated" means; it's the simultaneous inputs of rudder, elevator, and ailerons in correct proportion to make the plane track properly through a turn. How much of each will vary from plane type to type, and how sharp a turn you try to make. Just takes a bit of practice, it'll become natural.

Not to pick nits, but 86% + 50% = 136%. Can't have more than 100%.

I heard about coordinated turn too. I'd like to ask one question about it too. If you are flying the plane and you have to make a right turn its flying away from you not coming to you, if we make a right turn with aileron, gimbal moves towards right, rudder should be moving concurrent on the right side with aileron or it should be on the left side? ofcourse in order to maintain level, we use elevator as well, so making a coordinated turn we are supposed to use aileron elevator and rudder. Question is Rudder should be on right side as with aileron or opposite to aileron's movement?

Thanks

Mody

Normal flying, you move the rudder stick in the same direction as the aileron stick. Once the bank angle is established, you return the aileron stick to neutral but you keep using the rudder and elevator together. To end the turn, return rudder to neutral and level the wing with the aileron.

When you are flying inverted, the rudder stick is "backwards" but the aileron is not.

Thanks B.L.E. I understand it good now. while I fly inverted I don't use rudder, is it ok?

Mody

maybe a simpler (possibly wrong) way to explain this is just watch the fuselage during your turn. if it seems to be really nose high dragging the tail through the turn, a little rudder to compensate will level out your fuselage. if the nose is dropping, then some opposite rudder will put things level again. kinda the thing you need to just play with to figure out how much is enough or too much. depending on how steep your bank is, the more elevator you pull (if you are in a steep bank), the tighter the turn will end up.

Yes, people do it all the time. The sky doesn't fall if you don't do a coordinated turn, upright or inverted. Flying fields are filled with experienced flyers who don't use a rudder for much more than taxiing.

Once you get upright coordinated turns down, then start trying to coordinate your inverted turns. It won't make you rich and famous nor will it end wars and famines, it will only bring you more personal satisfaction.

True, it doesn't, unless you add them as vectors. Walk north 86.6 ft in a straight line and then turn 90 degrees and walk west 50 more feet in a straight line and you will be 100 ft away from your starting point.

Thank you for all of you guys detail explanation , I think I know what is the thing. At first, I want to try by mixing aileron and rudder in the radio to test coordinated turn, but after knowing it doesn't work when flying inverted, I decided to drop it out. May be I will try by manual input . I am not sure I can do it because it seems too much and clumsy for me to handle three inputs, A, E, R simultaneously during a turn.

Anyway, no harm to give it a try at enough altitude. Thanks again !!!!!!!!!

In the strictest interpretation of the question, a coordinated turn occurs as posted above when the drink on the table doesn't slosh in the least bit.

In a true coordinated turn the normal acceleration on the plane is straight down through the bottom of the plane as if you were flying straight and level.

That may OR MAY not require rudder to achieve on any given airplane. And unless you mount a rate of turn indicator in your plane and either videotape it or other wise record what it's doing in a turn there is absolutely no way to determine if you are in a true coordinated turn from the ground!

Adding rudder for the sake of adding rudder because someone said that makes it a coordinated turn is just wrong.

One test you can perform to test if you need to add rudder is fly the plane over your head and away from you. Now do an aileron turn in one direction. Note if the nose of the airplane goes the wrong way for a moment before it turns in the direction you've directed. If it does go the wrong way then you have a case of adverse yaw, and you should add a little rudder to start the turn. Now there is the possibility that the nose will go too far in the direction of the turn before the plane actually starts turning. Then you have proverse yaw and you actually need OPPOSITE rudder to make a coordinated turn. This is also the situation when you add rudder for the sake of adding pro turn rudder when you don't actually need it.

That's an apples and oranges comparison. My point is that you can't have more than the whole of something. Percentage is a fractional comparison, vectors are trigonometric functions. At any rate, I understand what you meant regarding how much rudder, how much elevator, etc for a given amount of bank.

To add a minor detail to (and completely obfuscate ) the discussion, an airplane will maintain a "neutral aileron" bank of around 17ish degrees depending on its configuration (wingspan, dihedral, high/low wing, etc).

At bank angles less than the "neutral aileron bank", the airplane will tend to shallow out due to inherent lateral stability.

At bank angles steeper than the "neutral aileron bank", the airplane will tend to increase the bank angle (overbank) requiring opposite aileron to maintain a steeper bank angle. Overbanking is caused by the different turn radii of the two wings. How this works is that a steeper bank angle means a smaller turn radius, and the radial difference between the inboard and outboard wing panels is larger as a percentage of the turn radius... Outboard wing is now flying faster, more lift, overbanking...

This probably has limited practical application for model aviaiton but I can go back to my Merlot now...

Cheers!

Jim

Well B.L.E,

Thanks for your reply its really a cool one, and I would like to say thanks to Oldman who started this thread and gave me an opportunity to learn something.


Thanks to all

Mody