krokodyl

To start off, I know that I have been asking lot's of questions recently, but hopefully one day I will pass on this info to others.

Anyways, I have the avistar elite, and since it lands FAST, I decided to put flaps on it. I have the dx6i and am going to buy the AR610. I can have flaps on the flaps switch and then more on the gear switch. I might even be able to get another position, not sure though. Anyways, should I use 10 deg, 20 deg, and 30 deg? If I can't get 3 positions I can do 10 and 30. Anyone tried this? I got the ARF version and I didn't see anything on this topic in the manual.

Also, I am bit confused. Is it 30 degrees of a full rotation of the servo?

Hydro Junkie

A servo rotates 60* each way. That being said, the servo arm and the control horn on the control surface will determine how far the surface moves. This is affected by location of the horn, length of the horn and arm and, ultimately, by the settings in the transmitter

RBACONS

My Feedback: (3)

If your main reason for implementing the flaps is that the plane comes in too hot, their may be easier/less expensive fixes. Typically, if a trainer lands fast its because the engine idle is too high, the prop pitch is too large, or the plane is balanced too nose heavy. Has a more experienced pilot checked out the plane and made a recommendation on how to slow it down?

krokodyl

Thanks for the reply. It is certianly not the idle, because I had 2 deadsticks before I decided to adjust the engine, and it still came in hot without the engine. I do have a instructor, he had it bounce when he landed to, although only a bit. Another experienced pilot who owns the plane told me that It lands fast without the flaps. I dont mind paying for the flaps because I got another airplane that came with a different radio, so I need another reciever anyway, so I will buy a higher channel reciever.

jester_s1

I guarantee your plane is nose heavy. A plane that is nose heavy loses elevator authority and drops its nose on landings, preventing a proper flare unless you keep the airspeed up all the way to the ground. If you have the plane balanced per the instructions, it's probably at 25% of the mean aerodynamic chord. Going back to 27% will give you a better behaved plane overall that gets tossed around by the wind just a little bit more. Try working out your CG setting before adding the flaps. You may decide you still want them anyway, but it's important to have a properly balanced plane either way.

As for your flap settings, you don't need 3 options. 10 degrees will hardly have any effect at all. You'll want to set up a mix of down elevator with the flaps to keep the plane from ballooning when you apply them. Start with 15 degrees of flap which still isn't much, and work out through experimentation how much elevator mix you need to keep the plane from changing pitch when you apply the flaps. Then go to 20 degrees for low flaps, and 40 degrees for high flaps. It will be smart to gradually work up to the 40 degree flaps so you can check your elevator mix and adjust as necessary, but if you have it right at 20 degrees it will be close. The 20 degree setting will be good for shortening your takeoffs, not really needed on land but very handy if you ever put floats on. The 40 degree setting will act as an air brake so you can make steeper approaches and float the plane in with a short approach if you want to.

jetmech05

Sure sounds like you are nose heavy. Or your approach is too steep.
I've flown the plane, didn't find in too fast at all
Now flaps are not speed brakes they are lift augmentation devices. You very well maybe trading one issue for another, like too much speed with flaps ballooning up. Not good on approach
.

hsukaria

I agree with the others, check and correct the CG balance before anything else. By the way, what engine and prop are you using? What is the engine speed at idle? That doesn't fix the CG issue, I know. But after you correct the CG, the engine idle speed and prop pitch will become factors to consider as well. I have never heard of flaps needed on a trainer. Furthermore, if you are going to set up the flaperon function on your radio, you will be sacrificing aileron authority. That will come back and bite you if you are landing slow with the flaperons down and not have enough aileron control.

krokodyl

Well, the CG is fine, maybe a tad tail heavy. I'm not going to use flaperons, but actual flaps that came with it, but they were locked. Its certianly not the idle, as I had a few deadsticks, and it still came in fast. Im using a 11 by 6 apc prop with an os 46 FX. I also don't think its my approach, because if I try to make it longer i will need to add throttle to prevent it from stalling.

Since I just got the hardware, I think its worth messing with them even if I get good landings without them.

hsukaria

No argument there. The prop is a good fit. You could also try a 12x4 prop to slow the plane down more when landing with engine on.

rgburrill

It might be that you just think it is coming in fast. Some trainers bounce on landing. At any rate nothing wrong with putting 30 degree flaps on it. But definitely test it at altitude so you can get the elevator coupling correct.

JohnBuckner

My Feedback: (1)

When the subject is flaps and the angles of extension it is always the angle of movement of the flap surface away from the in trail position of the airfoil. It is not the angle or travel of the servo output arm.

Now for the disclaimers I fully concur that flaps are not needed on a trainer, However this airplane (Avistar Elete) already comes with them and it is simple to activate with the addition of two servos and a Y chord. This converts it to a four servo wing. This is Not flaperons and there will be No flaperon mixing done in the transmitter. Just a two position switch is all that really needed, Ok three positions if you must although I do not recommend this.

Of the two dedicated flaps vs flaperons (which is just mixing in a flap fuction to your ailerons) dedicated flaps are far more desirable than flaperons.

Just a quick outline of what the flaps do:

Up to about 20 degrees they will increase lift and ad only a little drag.

Beyond 20 degrees they add considerable drag with not much more lift.

With those simple facts in mind when you do decide to mess with flaps my simple opinion is to set them just two position and down position no more than 20degrees. OK lets talk about what is going to happen the first time you apply the flaps. This should only be done in level flight and not when you are not trying to land. That first flip of the switch the airplane will pitch up maybe even shockingly so. You must be able to safely fly the airplane severely out of trim until such time you can safely trim it yourself. Only after you can do this would I ever suggest using flaps when you are new flyer.

Now there is a method of helping the pilot with this and it is a mix that is called 'Flap to Elevator'. What this does is when the flap is activated a preset degree of down elevator is applied. This does work and definitely helps the pilot however it is no pancea, it can take many flights to find the perfect combination and you will need to deal with big surprises each time. This is because no one is going be able to tell you that magic amout of down elevator to program, it is always hopefully an educated guess.

Most recently maybe three years now I got involved in Jets (actual turbines not the electric duct fans) and most of those have flaps and yes they really are needed to land safely and that is because of the residual thrust of the engines. Guess what at the three jet flys I have attended a very common conversation is that mix and how much down to program into it so the fellows don,t go bobbling all up and down every time they raise or lower the flaps.

This is not intended to scare you away krokodyl but only help you understand. I will shut up for now but there is much more to talk about when you get to the approach to landing phase with flaps down.

John

krokodyl

Ok, thanks guys. I'm not too good with programming radios, especially the dx8 that one of the instructors lent me, so I will ask him to help me set the radio, and go from there. There is also a guy with the same airplane as me using flaps, so I will ask him how much elevator mixing he pu in just to get a general idea of where to start from. I will test the flaps high up, to be safe.

Also, I just bought some hitec servos, and realized that they are not ideal, because they have karbonite gears. On hitec's website it sais that they should not be used on gas (not glow) engines. Should I be ok with my glow engine? All of my other servos are not karbonite, so I guess even if one of them failed, I could still hopefully land.

hsukaria

Gas engines usually generate a lot more vibrations than glow engines. The karbonite gears may not be compatible with gas engines because they are more brittle. Metal gears are usually recommended for gas engines. I know that is the case for bigger gas engines, don't about the new small gassers.

JohnBuckner

My Feedback: (1)

You don,t need anything fancy (fast or strong) for that airplane those servos will be fine in fact just plain old 'standards' such as the HS 425 or the HS 435 are all that's needed.

John

jester_s1

Karbonite gears will be fine. They are stronger than the standard nylon gears but can't handle the vibration of a gasser.

finewayne

HS 435 all the way!

RCFlyerDan

My Feedback: (54)

[QUOTE=krokodyl;12237018]To start off, I know that I have been asking lot's of questions recently, but hopefully one day I will pass on this info to others.

Anyways, I have the avistar elite, and since it lands FAST,
QUOTE]

The airplane doesn't land fast. You as the pilot are landing the plane fast, due to poor pilot technique and training. Try power to idle earlier in the landing approach and best glide on the plane will be the wing cord parallel to the ground.

krokodyl

Well, I already bought the servos and rx, so I will install them anyway, but I will try to master landings without them.

Also, when setting them up, how am I supposed to know how many degrees down they are moving? Do I need to use trial and error with a protractor? The transmitter uses percent.

Furthurmore, does anyone onow how I can use the buddy box with flaps (dx8 is maste, dx6i is slave)? I got them setup to some random position on the dx8, and some other position on the dx6i, but the dx6i has no control over flaps...

JollyPopper

My Feedback: (6)

First of all, you are not asking too many questions so long as you are sincere about them and not just trolling. I have seen nothing to make me believe you are trolling. I do believe you have fallen into the trap of over thinking a fairly simple situation. Adding flaps to an airplane that is landing too fast is not a fix. It seems that you want flaps and have already made up your mind that you will have flaps and that is all right, but it is not the fix to your problem. Fix whatever is making the plane land too fast if it is in fact landing too fast. The guys have already covered several times the three things that will cause fast landings. Find the problem and fix it. It only takes a few minutes to change the prop. You insist that the engine idle is not a problem, so we can rule that out. It does take slightly longer to change CG, but it is relatively simple. FIX THE PROBLEM. Then add the flaps if you want them and have fun with the plane.

RBACONS

My Feedback: (3)

If you want the slave transmitter to be able to control the flaps, you need to make sure your master transmitter's Trainer Mode is set to Inhibit (or Programmable Master with all the channels set to transfer). If you set the Trainer Mode to Pilot Link Master, only the sticks on the slave transmitter will work. Read your manuals or pull them off the web if you don't have them.

krokodyl

Ok, so I was reading over the manual, but it does not seem to say anything about having dual aileron and dual flaps. I hooked up the flaps to the flap channel using a y cord. The flap switch operates the flaps, but they for some reason work as ailerons too?!

Also, I have a feeling I will need another y cord. I have a 6 channel rx, and Im not sure if i can get away with only one. Otnerwise one of the ailerons would have to be hooked up to the gear slot, or the flaps would have to be hooked up somwhere else. Anyone know if its possible to do this with only one y cord?

Edit: OK, so I got it to work on the dx8, however when I hook up the dx6i as the buddy box, and presss the button on the dx8, one flap goes full down, and the other one I can control with the dx6i. I should be able to get it figured out after messing around with the settings... My fla+safe in aux, and in gear...

Thanks guys

jester_s1

You should be able to Y your ailerons and then use 2 channels for your flaps. Both of those radios have the programming to mix channels 5 and 6 to make the flaps work. And no, you don't need a protractor. Flaps are not super precise surfaces. You can tell easily enough what 45 degrees looks like, so just under half of that is 20 degrees. Don't over think it.

That said...

If you are still on the buddy box, you have no business messing with flaps. As others have said, the Avistar is not a hot landing plane. Ask your instructor what he thinks. It may just be that it feels fast to you because you are a beginner. If that's the case, the best thing you can do is deal with it until you get comfortable. Super slow landings bring their own problems that require much more skill to handle than just dealing with a bit more speed, namely the effects of wind gusts on a slow and draggy plane that's 2 feet away from the ground. It is a very common beginner thought to want to add features to a plane or tweak the way it works to make it easier to fly in some way. But that usually goes badly. I've seen people who want to mix elevator with rudder so they don't have to pull back on the right stick during turns, others have added Fultz landing gears to keep from bending the nose gear because they don't want to learn how to land on the mains, and others who switch planes entirely after only a couple of weeks of learning because the skills aren't coming fast enough to suit them. I do truly understand the urge to tinker when this hobby is new. And that urge never really goes away. But at this point, if you have a smooth flying plane that is balanced right and the landing gear is set up right, you really should leave it alone and just learn how to land with it as it is.

krokodyl

I'm still having problems setting up the dx6i. Since I want takeoff and landing, I needed to mix in the gear channel. Then when I go to setup the ailerons, I can only get the one on the aileron channel to work. If I try to use the ailerons on the Y, then the flaps dont work properly. Unless if someone knows how to set it up, I will have to use the two position switch, with only full up an full down.

jester_s1

I forget, does the DX6i have a 3 position switch for flaps? If it does and the gear channel is proportional (it's not on some radios), you can make 6 the master and 5 the slave for the mix. If not, you'll have to settle for an on/off setup for flaps. You definitely don't need takeoff flaps for an Avistar though. As stated before, you really shouldn't use the flaps at all at this point in your learning. They'll add some fun to your flying in a couple of months once you are soloed and have your landings looking good conventionally, but as a beginner you will just add another complication to a system that already works beautifully if it's set up right.

AllModesR/C

Krokodyl, are you flying at a field around Chicago? I ask because there was an instructor there with an Avistar. BTW, what kind of wind speed are you flying in?