Help for programming fixed wings
Very often I'm reading in a forum, or I see it with my own eyes on the field, that beginners and also experts have many problems with the correct set up of a model on their transmitter. At first sight, this a nearly impossible problem for beginners but with a little bit of time, they will also get so far that the plane will airborne. Not seldom, the difference between a plane that flies very good and one that can only remain in the air can be found in the programming. Also the programming can make a difference if the plane is very easy to fly or very difficult.
I will here explain the basics which can be used on any transmitter or brand, please understand that I can't go into details like the correct assignemt of the channels, this should everybody know for their own transmitter.
I will here explain the basics which can be used on any transmitter or brand, please understand that I can't go into details like the correct assignemt of the channels, this should everybody know for their own transmitter.
Mechanical setup:
The basic to set up a model correct is a correct mechanical setup. Follow these guidlines for a good result:
I can't tell you any numbers for the weight, this is different for every model, but if it isn't a slow flyer, it should at least to be able to move a heavy screwdriver. If it won't move, please don't even think of flying!
- Y-cables are a waste of money, whenever you are using a model with two aileron servos or two elevator servos, always use a seperate channel for each servo. With a y-cable you can't set up things like differential or spoilerons.
- Set the servos to the neutral position before you are putting them into the model. This can be done with a transmitter or a servo tester.
- Mount the servo horn in a 90 degree angle to the servo.
- Set up the hinge that way, that you will have the full mechanical way with 100% servo travel.
- Put weights on the moving rudder and test if the servo is moving correct. If it won't travel or only step by step, the servo is too weak.
I can't tell you any numbers for the weight, this is different for every model, but if it isn't a slow flyer, it should at least to be able to move a heavy screwdriver. If it won't move, please don't even think of flying!
Transmitter set up:
Mechanical set up is done, now we need to do the electronical one.
The hinges was setup as good as we can do it, but in real life, there will be always some fine tuning necessary, here is how you should do it:
now we get to the second function which can be very useful:
DR: DR is the abbreviation for Dual Rate and means nothing else then a symetrical shorten of the servo travle. many people are using the DR for the set up of the travel, but this is false and it was not designed for that. With some models, you need other travel ways for starting and landing then for flying, for this you should use the DR function. You are only TEMPORARY changing the travel and you can switch that on or of with a switch.
Expo: Expo is the abbreviation for Exponential and means the curve stick/servoposition. If expo is not activated, you have a linear curve (straight), if the stick is 0, the servo is 0, if the stick is 20, the servo is 20, at 50 50 and at 100 100. if you are using expo, then you don't have a straight curve, you'll get a exponential curve (google), means with a stick position of 0, the servo position is 0, if the stick is 20, the servo position is 15, at 50 35 but at 100 it is again 100. What does this means now in real life? Around the middle of the stick, the model will be less agressive, because the servo travel is in relation less then the stick travel, but with full stick travel, you still will have full servo travel. Expo can do real wonders and normaly, no model should by fly without it. Depending on personal taste and the model, expo can vary very much, but most time the manuel for a model is proposing something. if there is no proposal, I would normaly start at 15% expo on the elevator and 30% at the aileron. On a 3D model with much travel of course more, and on a slow beginner EPP glider less.
Congratulations, from the point of the servo set up, the model is now ready for take off, but there some other things that should be considered before starting:
The hinges was setup as good as we can do it, but in real life, there will be always some fine tuning necessary, here is how you should do it:
- Check the servo direction and reverse it if necessary.
- Set up the correct neutral position.
- Set up the travel with the servo travel function.
- When using e.g. two aileron servos, meassure then the travel on the rudder. If one has more travel then the oder, reduce the travel on the bigger one to have the same travel on both sides.
now we get to the second function which can be very useful:
DR: DR is the abbreviation for Dual Rate and means nothing else then a symetrical shorten of the servo travle. many people are using the DR for the set up of the travel, but this is false and it was not designed for that. With some models, you need other travel ways for starting and landing then for flying, for this you should use the DR function. You are only TEMPORARY changing the travel and you can switch that on or of with a switch.
Expo: Expo is the abbreviation for Exponential and means the curve stick/servoposition. If expo is not activated, you have a linear curve (straight), if the stick is 0, the servo is 0, if the stick is 20, the servo is 20, at 50 50 and at 100 100. if you are using expo, then you don't have a straight curve, you'll get a exponential curve (google), means with a stick position of 0, the servo position is 0, if the stick is 20, the servo position is 15, at 50 35 but at 100 it is again 100. What does this means now in real life? Around the middle of the stick, the model will be less agressive, because the servo travel is in relation less then the stick travel, but with full stick travel, you still will have full servo travel. Expo can do real wonders and normaly, no model should by fly without it. Depending on personal taste and the model, expo can vary very much, but most time the manuel for a model is proposing something. if there is no proposal, I would normaly start at 15% expo on the elevator and 30% at the aileron. On a 3D model with much travel of course more, and on a slow beginner EPP glider less.
Congratulations, from the point of the servo set up, the model is now ready for take off, but there some other things that should be considered before starting:
Mixer:
Mixer are a necessary evil thing that can be very useful. A mixer is mixing one function to the input function from the transmitter. E.g. you can mix, that the rudder will also move when you are steering the ailerons. Also mixing functions can be attached to a switch or a slider, so that, e.g., a glider is using the ailerons as spoilerons for landing. And there we are comeing to a problem which is brought to us by the mixers:
In the first step, we set up the servo travel so that we have 100% of the mechanical way, so lets look at a glider where the ailerons are put up 100% as spoilerons. If we are now steering with the ailerons, one will try to get up, but it is already in the end position, so what will happen? In the worst case, this will lead to a not anymore workuing aileron and the plane will crash because the servo died, the aileron was mechanicaly damaged etc.
We can solve that problem easily if we are using one function, that surpriseingly many people don't even know, the so called servo travel limit. This should not be messed up with the servo travel, this is something way different. The servo travel selects how far the servo will travel when moveing the stick, but the travel limit is one value, that the servo won't exceed.
Comeing back to the example with the glider landing with spoilerons: Both ailerons are now in the 100% up position, so we will set the travel limit to 100% up on both servos. If we will now move the aileron stick, the aileron which is standing up will not move even a mm because it already reached the limit of 100%, but the other aileron will go down normal and a safe landing is guaranteed.
In real life, the 100% will not fit, but the easiest way for the correct travel limit is to set it up after the set up of the servo travel and before programming any mixers. Therefor you can go into the servo monitor of your transmitter and write down every value for the maximum travel of all servos. Then you go back to the servo set up and use the noticed values a limits.
In the first step, we set up the servo travel so that we have 100% of the mechanical way, so lets look at a glider where the ailerons are put up 100% as spoilerons. If we are now steering with the ailerons, one will try to get up, but it is already in the end position, so what will happen? In the worst case, this will lead to a not anymore workuing aileron and the plane will crash because the servo died, the aileron was mechanicaly damaged etc.
We can solve that problem easily if we are using one function, that surpriseingly many people don't even know, the so called servo travel limit. This should not be messed up with the servo travel, this is something way different. The servo travel selects how far the servo will travel when moveing the stick, but the travel limit is one value, that the servo won't exceed.
Comeing back to the example with the glider landing with spoilerons: Both ailerons are now in the 100% up position, so we will set the travel limit to 100% up on both servos. If we will now move the aileron stick, the aileron which is standing up will not move even a mm because it already reached the limit of 100%, but the other aileron will go down normal and a safe landing is guaranteed.
In real life, the 100% will not fit, but the easiest way for the correct travel limit is to set it up after the set up of the servo travel and before programming any mixers. Therefor you can go into the servo monitor of your transmitter and write down every value for the maximum travel of all servos. Then you go back to the servo set up and use the noticed values a limits.
Delta or flying wing:
Delta and flying wings differ in one big thing from other classic planes. Delta and flying wings only have two rudders which are both used for aileron and elevator which are called ailevons. For setting up these, you should follow this:
Plug both servos in the correct receiver channel. Check now, if the control functions are working in the correct direction. Are both functions on one servo upside down, just reverse the servo. Is only one function upside down, unplug both servos and swap their position on the receiver. After that, and maybe a servo reverse, it should now work correct.
The maximum servo travel will be set up same as with a normal plane, but with the difference that you only have to do it for elevator or aileron. Also it is very important to set here now the travel limit! Also, as difference to the normal plane, you need now DR here in the initial setup. A delta or flying wing is normaly more agressive on ailerons, so you need to set DR on the ailerons because you can't reduce the servo travel only for ailerons. Also the expo on ailerons should be around 20% at least for the maiden.
Plug both servos in the correct receiver channel. Check now, if the control functions are working in the correct direction. Are both functions on one servo upside down, just reverse the servo. Is only one function upside down, unplug both servos and swap their position on the receiver. After that, and maybe a servo reverse, it should now work correct.
The maximum servo travel will be set up same as with a normal plane, but with the difference that you only have to do it for elevator or aileron. Also it is very important to set here now the travel limit! Also, as difference to the normal plane, you need now DR here in the initial setup. A delta or flying wing is normaly more agressive on ailerons, so you need to set DR on the ailerons because you can't reduce the servo travel only for ailerons. Also the expo on ailerons should be around 20% at least for the maiden.
V-tail:
A v-tail is from the programming side nothing else then a delta, the only difference is, that not the aileron and elevator is used but the elevator and the rudder. So the setup is analog to the delta or flying wing.
There is still a small trick: most times, for the v-tail a differential is needed for the rudder but most transmitter don't have that function. But you can do that very easily with a mixer: just mix down elevator in both directions of the rudder. of course you need to test it on your own model if you need down or up elevator and how much.
There is still a small trick: most times, for the v-tail a differential is needed for the rudder but most transmitter don't have that function. But you can do that very easily with a mixer: just mix down elevator in both directions of the rudder. of course you need to test it on your own model if you need down or up elevator and how much.