Yaw stability

[alaskabearhawk]

FWIW. With only 9.4 hrs so far, I haven't had any issues as long as my hands and feet remained quiet. I flew at 75% power in pretty much a constant turn and it was relatively easy to keep in trim. I had a rich mixture setting, running always on BOTH tanks selected. My longest flight was 3.1hrs turning circles. The most differential between tanks that I have seen in refueling is 1.6 gallons.

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[Utah-Jay]

This is all interesting reading…. I have yet to fly but did not like the look of the springs in the kit and put on mildly stiffer springs during construction

[500AGL]

It’s easy to get caught up in possibilities online. I myself get sucked in.

This next statement is nothing more than stating my opinion. (So please don’t take it the wrong way. There is always someone better at it and with more time than yourself)

I have roughly 500 hrs in a patrol, and close to 100 in a model 5. I have somewhere around 1500 in tailwheel aircraft. I have not seen any yaw instability in a Bearhawk.

Pb

[Rspencer]

Where does one get the C142 springs? New to a Bearhawk 4, used to more spam can style planes so as I’m only a couple hours into the Bearhawk 4……..the ball is all over…….I have been convinced it’s an issue, but maybe it’s just me. Haha. Thanks.

[TimTall]

Who convinced you it's an issue? I've let a number of high time guys fly my 4-place and the ball is all over the place for the first while. They get used to it eventually but it takes some time. The powerful rudder that causes that "instability" that people talk about is a feature once you know how to use it.

I used the springs that came with my kit.

[Rspencer]

I convinced myself! lol. Working to break that mindset and “learn to fly it” as I have read on here!

[jaredyates]

Here are some thoughts about yaw stability and learning to master coordinated flight in the Bearhawk or most other planes.

Every few months I'll fly Young Eagles in the Bearhawk, and they typically steer the plane for most of the flight. Often this is the first time they have ever steered a plane. I spend about a minute explaining to them how the controls work, with me steering and them following along with their hands and feet on the controls, so they can understand the scope of how far we are moving things. Then, I turn them loose and tell them to figure it out. They do surprisingly well.

Sometimes, I have the opportunity to go flying with someone who has never flown an airplane that requires feet, but maybe has hundreds of hours. Sometimes it takes them much longer to catch on than it does the kids who have never flown before.

I haven't kept accurate records but I can comfortably say I have passed the controls of a Bearhawk to several dozen people and likely over a hundred.

If we were flying, here's what I'd show you. First, with all feet on the floor, input left stick. The wings will bank left, the nose will slide a little right. Now, reverse the aileron input with an equal amount of stick, but to the right. The wings will bank right, and the nose will slide waaaaaay left. That's the first part, intended to demonstrate that the stick controls the bank, and any time the stick is displaced from neutral, the adverse yaw will point the nose the wrong way. The more stick you use, the more it does this. If the stick is neutral, the yaw goes away. This will become important later, and we need to understand that pilot stick movements will also induce yaw movements, and if we move the stick less, we make less work for ourselves in yaw.

Now for the second step, with the stick neutral, press the left pedal. You'll feel a leaning sensation. Any time you feel a lean, you fix it with your feet. How do you fix it? Press with a foot. If it gets worse, that was the wrong foot, try the other one. Unless we are going to intentionally fly uncoordinated, we should always feel straight up and down, no matter the bank angle. If we have doubts about our calibration, we can always check the ball, but we get the most information from feeling the lean, and from looking out the windows. Can you see that in addition to the lean, the nose is sliding left or right when we press left or right with our feet? With minutes of practice, you'll begin getting much better at listening to the airplane's coordination and feeling subtle leans. We learned before that moving the stick caused the nose to slide. Now we know that pressing a pedal makes the nose slide. So what we have to do is use the stick and pedals together, to make the nose not slide, which leads us to the next step.

This is as far as I make it with most Young Eagles, at least until their second flight.

The next step is to practice maneuvers that will help train your hands and feet for how the ailerons and rudder are coupled, so that you can anticipate and maintain coordinated flight all along, rather than having to "feel the lean then fix it" as we did before. There are two categories of maneuvers that will help us accomplish this: coordinated, and intentionally uncoordinated. First, coordinated: initiate a turn to the left by adding left stick and left foot. Once you reach a desired bank angle, immediately initiate a turn in the opposite direction. Right foot and right stick, to the same bank angle but on the other side. Repeat this rolling back and forth, back and forth. The airplane should always feel as though it is pivoting on is longitudinal axis, and the nose should be pinned straight ahead. If you are doing well, the nose will not slide left or right at all. If you use a bank angle of around 15 degrees and you make smooth inputs, this will be pretty easy. If you use aggressive aileron inputs and 30+ degrees of bank, it will be hard. For most people, this will take hours, not minutes, to fully master. Sometimes this maneuver is called "dutch rolls" but I don't call them that because there is also another thing called dutch rolls, and that thing is different from this and has to do with neutral/negative stability and roll/yaw coupling that is most often noticed in certain big jet planes that didn't have yaw dampers.

Now for the intentionally uncoordinated training maneuver. Start straight and level, and for this exercise, try and maintain exactly zero degrees of bank the whole time. Pick a dead bug on the windscreen. Make that bug transcribe a perfect square. Slide the nose left (left foot+right stick), this is half of the bottom of the square. Then pitch up- this is the left side of the square. Then slide the nose right (right foot+left stick) twice as far as you slid it left, this is the top of the square. Then pitch forward- this is the right side of the square. Then slide the nose left again, half as far as the right slide- this is the second half of the bottom of the square, and you are back where you started. If you make a very small dainty square, this will be pretty easy. If you make a very big giant square, it will be harder. Once you have mastered the square, try an equilateral triangle. This is sort of like drawing with an etch-a-sketch. The square involved moving the dead bug in one axis at a time (yaw or pitch), though it required as many as two axes of control input at once (yaw and roll, because they are coupled). Unlike the square, a triangle will move the dead bug in a diagonal line, so you'll need to introduce yaw+roll and pitch simultaneously, all three axes and all three controls. Because of this, I think the triangle is harder than the square. If you are feeling like Chuck Yeager and all of this is easy, then do a circle, or start cursive letters. If you can remember how to make a capital cursive G, then that's pretty extraordinary. The bigger the figures, the harder the exercise.

If you spend several minutes doing these maneuvers, I think you'll very quickly start feeling more comfortable with handling the airplane. You'll realize that the roll and yaw are always related. You can also add complexity by changing the airspeed, because as speed changes, each control also changes its effectiveness. Practice especially at 50 knots indicated, since that is the landing flare, where you will need to be a very good master of roll/yaw coupling in order to ensure that you are straight when you touch down. Take a break every now and then, pick a curvy road or river, and see how closely you can follow its contours. The more you can look outside of the plane and the more you reverse from left to right banks, the more learning opportunity your brain will have.

I should really try and make a video to explain these things, because that would be much more effective than words.

Having said all of that, since you have only flown your plane and not any other Bearhawks, there is still the possibility that it is not rigged right or that it is not handling like a Bearhawk should. This is hard to troubleshoot by forum messages unfortunately. Get some videos or some data dumps if you can.

[jaredyates]

Thank you Roger, learning is one of my favorite things and I'm right there with you on that concept!

[Bcone1381]

You should name these exercise! Did you create them, or are they widely used in the CFI arena? As a weight training and stretching improves/strengthens the body so do flying exercised improve ones flying skills, Jared. Thanks!

[jaredyates]

These are definitely not my creation. I wish I could remember who I learned them from over the years.

[Rspencer]

Happy to get videos and share!

for context, I am a very active GA flyer. Mooney, 182’s, Seneca, Husky’s, Chinook 2+, Murphy Rebel (my prev bush plane.) . I am a career big jet pilot, who on his days off flys my Murphy Rebel Bush Plane off airport frequently and into all sorts of fields, river banks, sand bars, ect. I Have roughly 5K flight hours. BUT, everything I have flown is more in the spam can category. And while I fly TW a bunch in the Rebel and Husky, they too, are very spam can and auto coordinated. So I am familiar with keeping the feet moving, what I guess I am not familiar with is the coupling of my feet to the ailerons………

anyways, this is all great advice. And I will go up and do all these things. Strangely, landing was my best place in the Bearhawk. Flaps 3, down final I noticed significantly less issues with coordination. Probably many reasons for that. Takeoff and climb are my weakest points for remaining coordinated. Cruise no issue, just keep feet on pedals and constantly adjusting lightly. Of course I will continue like I began, in good weather conditions and light winds until I improve!

as for my plane, it’s got some extra Dihedral, but I’m told that was ran by Bob and approved to the builder to get some more gravity flow for the aux tanks preventing a need for fuel pumps. The rest of the rigging looks ok, I’m adjusting the ailerons reflex a bit as they are a bit excessive. I am also considering building and adding a nice strake fin on the underside tail. This one has mount holes already there, but the strakes it had on it before were not aligned properly with a straight fuselage, they were angled toward one another. I’m thinking a larger single straight one like I have seen on another Bearhawk on here may be beneficial for my desires.

anyways, I appreciate this info, and I will be doing these maneuvers over the next few weeks to reprogram myself!

[Nev]

I found it interesting to try different aileron reflex positions. The more reflex (within reason), the lighter the controls felt in roll, with a corresponding small reduction in adverse yaw.