goony

anyone got it sorted yet as my 46 is terrible?

goony

EXCAP232

My Feedback: (12)

Give us a little information as to what your need is. Are you asking about the plane named "Harrier" or the 3D maneuver named "Harrier"? What .46 and what propeller?

EXCAP232

Dealspeed

My Feedback: (17)

Hes talking about the Seagull models Harrier3D 46, It has horibble KE Coupling, Mine actully isnt to bad, its when i give full rudder to get into a really high alpha KE it gets alittle tricky to control, check your lateral balence this will help abit.
GL [8D]

tIANci

goony - what happens when you try to KE, how does the plane fly? Tucking to the belly or pulling to the canopy? Bad aileron coupling? Let us know and we can then slowly sort it out. My Harrier 60 will KE well with little coupling, I don't have to mix it out.

Not24

My Feedback: (1)

If his flies like mine, it has roll coupling first, then pitch coupling comes in later. You can't simply move the rudder on that plane and not have to move the right stick in two directions. It is possible to get a good ke, but you need speed and small rudder inputs to stay smooth with it. It's impossible to go full rudder for very long without it snapping out. I fly mine mostly on 50% of max throws on all surfaces, but I could still stand to tune it down some. Even with gobs of expo, it's just got too much maneuverability.

As for the knife edge, it rolls out, so you need to feed in opposite aileron, then you need to pull the nose up with elevator. The bad thing is that you can't simply hold the sticks still and watch it go by. You need to keep both sticks moving all the time, like you are trying to balance on a beach ball on one foot. It just likes to wander around, and for every angle of attack, there is a new control combination to stay straight. That's the best way I can describe it. The more nose up it is, the harder it is to fly.

tIANci

Yesterday I learnt about CG and pitch coupling in KE. I took my EP Fliton Prodigy up and it had 1 oz on the nose and the KE has always been so sweet, almost literally no coupling. I decided to take the 1 oz out and move the battery further up front. Once I removed the weight the plane flew amazingly good but when I went into KE the pitch coupling was NUTS! Hmmmm ... CG is so important.

Dealspeed

My Feedback: (17)

Not24 nailed right on the head, that is exactly what its like when i KE the plane wanders everywhere and your thumbs are always moving, Its not to hard anymore but iv gotten very used to already, although i only give about half input on my rudder when i KE much smoother and easyier this way

goony

as this is my 1st 3d model you can understand my problems, as stated already its a hand full compared to my usual general sport type models where you have to give it full rudder for knife edge SO maybe im just giving it too much rudder ill try it again todat SAT and report back later

goony

goony

much better today keep the speed down for high alpha KE and as it speeds up release more rudder but its still a handfull though?

goony

former spad

There are a lot of different factors involved in getting a plane to knife edge. I strongly suggest you get aerobatic trim charts and study them to help understand all the things involved. Basically, they tell you how to adjust your plane to get it to KE. I have had planes KE on first flight. Others, I can't get a good KE no matter what. Keep an eye on this sight, I will get some more information together for you in the next day or two. I just don't have the time now.

goony

ok thanks very much

goony

former spad

Here are the very basics needed to get a good knife edge.

First is the design of the plane. Large fuselage side surface area, symetrical wings with little or no dihedral, large rudder that has longer chord at bottom, and good engine power and proper thrust angles are all found on good aerobatic designs and contribute to good KE. Compare a Cap to a trainer.

Center of gravity CG is next thing to understand. If your plane is nose heavy and you must use up elevator trim to maintain upright, level flight, when you roll to KE, that same up elevator trim makes the plane pull to the canopy, out of KE. Tail heavy is just the opposite. Improper engine thrust angles can do the same thing to a lesser degree.

Yaw/roll coupling is next. To see roll coupling, in upright and level flight give rudder only control input, if your plane starts to roll the wings into a bank, the rudder is causing it to roll. To see yaw coupling give aileron only control and watch the plane turn and change heading as the wings bank/roll. Only the best acrobabic planes are designed without this coupling. Computer radios use premixes to program a small percentage of the opposite control to eliminate the coupling. For example, if the plane rolls right with right rudder only input, mix in a little left aileron to keep the wings level when you use rudder.

This is why the aerobatic trimming charts are so important. They take you through the whole process step by step to properly trim the plane for aerobatics. The idea is to trim the plane so that you can find the "sweet spot" in KE where the plane is able to pretty much able to stay where you put it, especially in KE. It is almost imposible to KE when you have to constantly manually correct every control to compensate for poor trim set up. You’ll be surprised how easy knife edge is with the proper plane properly set up, and why it is almost impossible with the wrong plane or wrong set up.

Not24

My Feedback: (1)

It sounds like you put a lot of thought into this, but I have to be an idiot and disagree with you. While you may be right as far as trimming goes, I think you are wrong about the design parameters for good knife edge flight. Those features you mentioned make a lot of sense, but they can easily be overcome by other aspects of airframe design. Dihedral may be a feature that you need to eliminate coupling, depending on wing placement, sweepback angle of the leading edge, and other things such as aspect ratio of the wing. By your definitions of what it takes to do a good knife edge, the Harrier should excell at it, but it does not. Meanwhile, an Avistar trainer with a 46 will hold a perfect knife edge all day long. I was disappointed with the coupling issues of the harrier, and trying to mix them out just made matters worse. What I am saying is that when you put a plane on its side, there are many many factors that affect its stability, and they all work in harmony to get a good flying plane, but there are really no hard fast rules as to what you must have to get a plane to fly on its side.

former spad

Don't get mad at me, but I agree with you 100%. There are a lot of other factors related to a particular plane being able to KE, I was just trying to mention the BASICS, so he could develop a better understanding of where to start. I have never seen a Harrier fly, I have no idea what it is capable of. I have been involved in other situations as the student while learning myself, or as the instructor trying to trim out a trainer for another guy, and going back to the basics can really make a big difference. If someone tells me he has been through the entire trim chart sequence and can't get the plane to KE, I will tend to believe him more than someone who claims a plane won't KE at all. I think I remember reading a magazine review that said the plane does great KE, but I can't remember for sure. There are rules that make every plane fly. Tweeking them to get your plane to do what you want is the hard part.

former spad

I went back and reread this thread. My question to you guys having problems with KE is have you followed the steps listed in the aerobatic trim charts or not? I suspect you haven't, but you tell me. Try reducing control throws, especially ailerons, and increasing EXPO for KE, it seems you're overcontrolling it. Instead of simply rolling into a KE from level flight, pull the nose up to 45 degrees, or more, and then roll to KE with lots of power. This gets the plane on it's side while minimizing the roll coupling of the rudder because this technique minimizes use of the rudder. Remember, you're trying to find that sweet spot. As you're finding out, it is a whole lot easier to find where the sweet spot isn't.

Not24

My Feedback: (1)

I don't want you mad at me either, but I suggest you fly a harrier, especially the 46, and then tell me what you think about its KE ability. The model is very deceiving. One would think it would be great, but my somethin extra blows it away (in knife edge only). a more fwd cg may help it out, but then you lose the harrier ability.

former spad

I'll stick with my Katana. But I did find other threads where guys said they could get Harrier 46 to KE.

Not24

My Feedback: (1)

Lucky you! I just got back from flying my Funtana. It does really good knife edges. The Harrier does them, but it takes a really good pilot to make it look right. Can you say Smooooooth?