Swash plate

[galaxy24]

I recently upgraded from my 4 channel flybar to the Mini CP. I understand that this heli is going to require more skill to fly, which is why I purchased it. However, I am finding it extremely difficult to fly. I am open to this being due to a lack of skill also. LOL. I just want to have a better understanding of this technology and hopefully someone can give me some feedback on how the gyro is supposed to work.

This is what it is currently doing:
(With the motors disconnected and the throttle at 50%)
(To begin with the swash plate is level with the ground when the heli is level with the ground)

If I tilt the heli tail down the swash plate will tilt forward, keeping the swash plate level to the ground, however, when I return the heli to level the swash plate will not be level to the ground.

If I tilt the heli nose down the swash plate will tilt backward, keeping the swash plate level to the ground, however, when I return the heli to level the swash plate will not be level to the ground.

Is this normal behavior? I don't have a lot of experience with this technology so I am not sure if something is wrong or if this is something that I have to learn/compensate for.

If this is not normal, is there a setting on the radio I can change to correct the problem?

Thank you,

Shawn

[The Mechanic]

I have a Mini CP as well. I like the design and except for the canopy has proven to be very tough. I upgraded both the main and tail motors to brushless motors using the Walkera plug n play upgrade kit.

The gyro is programmed to maintain the pitch, roll and yaw axis of the helicopter in the last commanded attitude until commanded to do something different. So, if you pitch the nose forward and then return the stick to neutral for example, the helicopter will stay at that pitch attitude until you send another command. The gyro compensates for changes in torque and other external forces to maintain present attitude. The gyro is always active and requires that you do not set any trim. Trims must stay at neutral.

As you have probably already found out by reading, all flybarless gyros pretty much do the same thing and reading other posts (for any FBL heli) can give you a lot of information.

The best way to test the gyro (on the micro helis) is to fly it and see if it works right. They usually do unless the circuit board is cracked in a hard crash. Check the rigging of the swashplate for level and rotor blades for zero pitch. If they are off the heli will veer to some direction instead of lifting straight off the ground. Look at the manual for a larger heli, like a T-Rex 450 for example, to see how the rigging should be done. Mini CP is the same only smaller.

The Mini CP is a rascal. It can really respond to stick inputs. Dial down your rates in the transmitter to 75 or 85 and turn up the expo to at least 40 to start out. Copter X 350mah batteries commonly found on Ebay at a good price work good in the Mini CP. The 250mah batteries don't seem to have enough capacity in my experience.

If you haven't learned to fly a collective pitch helicopter in a simulator yet you can save a lot of money from crash damage by getting a simulator.

[The Mechanic]

I checked my Mini CP. It doesn't do what you're describing. The swash stays more or less level when the heli is tilted and then returned to level. I don't have any theory right now why yours wouldn't work right.

[galaxy24]

Thank you for the reply.

I noticed this weekend about how it retains the last command it received until it is given a new command. Figuring that out helped out some.

I am going to make those setting changes you recommended for the rate and expo. I currently have those settings set at their defaults. I think these two setting changes will help out a lot!

I inspected the board and I do not see any damage. I haven't crashed it that hard. I am not sure what is happening with the swash plate not returning to level.

I will try to make those setting changes tonight. I will let you know how it goes.

Thanks again for the input.

Shawn

[The Mechanic]

I thought of something you could check. In the transmitter check the "monitor" display. That displays a set of bar graphs that show the outputs of the channels. When the sticks are at neutral the bar graphs should also be at neutral. You can calibrate the transmitter if they're not. Also, don't forget trims must always be at neutral. The gyro does all the work.

Also, you may be able to slow down the main rotor by adjusting the throttle curve for the setting you're using. For indoors you want just enough rotor speed to be stable. Like I said, the Mini CP is a rascal!

[galaxy24]

Yesterday before flying I made the checks and changes you had recommended.

Everything in the monitor section was good. When the sticks were at neutral the bars were at neutral as well.

I did have the trims tweaked a little. So I put them back to neutral.

I made the changes to the rate and expo as well.

So the results were good! I was flying in a more confined space yesterday and I was able to navigate much better than before. It will hover for a few seconds then drift off in a random direction but after I made these setting changes I was able to hold a much tighter hover than I have in the past.

You mentioned before about throttle pitch. For my skill level now it would help out a lot if I could desensitize this stick movement. I am going to research on how to make this setting change on the radio.

As always, thanks for the recommendations. It is fun to see the progress.

Shawn

[The Mechanic]

Glad to hear things are going better. Flying the Mini CP indoors is probably on of the most difficult situations because of the small space and the performance of the heli. You would be surprised at how much easier it would be in a gym or outdoors. But I think I learn faster flying in the house because you have to be precise. Don't be discouraged if it seems too hard. You'll get it.

The collective stick changes the rotor pitch and the throttle. Some people fly in "normal" mode and change the pitch curve as well as the throttle curve to their liking. I only use "normal" mode to slowly speed up the rotor (the Mini CP doesn't have soft start) to about mid stick and then switch to "idle up" with a V shaped throttle curve. I leave the pitch "curve" a straight linear line from full negative pitch with stick down to full positve pitch with stick up. You can add expo to the pitch curve to make it softer in the middle or you could add negative expo to make it more sensitive in the middle.

The V shaped throttle curve can be shapped any way you want to make the motor speed just fast enough to give good power and stable flight. You can move the V down for over all slower speed and you can "flatten out" the curve so the throttle is less sensitive to stick changes. Max power would of course be 100% throttle all the time but that is a waste of power. On my big helis I use a 100 95 90 95 100 curve. On the Mini CP (I have a brushless motor not the stock motor) the throttle curve is something like 85 70 45 70 85. You could try a throttle curve of 60 50 45 50 60 just to see how it works. The idea is that as you change pitch by moving the collective stick either up or down you also increase the throtlle.

Since you're not flying upside down right now you're not so interested in the negative pitch of the rotor but there is a huge advantage to becoming used to flying in idle up because that gives you more or less a constant rotor speed. This is very advantageous when flying outdoors in the wind as it give you good control all the time. That is the advantage of a collective pitch heli. The problem with fixed pitch helis is you must slow down the rotor to lose altitude and when that happens you lose control authority in the pitch (nose up and down) and roll axis.

[galaxy24]

At this point in time I don't feel confident enough to switch between these modes. However, for fun I tried to set them up and I dont think they came out just right. My V looked a little lopsided with those settings. I don't understand why since they are symetrical. I would have to admit though that I don't completely understand these settings. So that is probably most of my problem.

What I did do though was in the throttle curve was drop the H value down a little. This of course decreased my max throttle, but I dont fly there anyway. It seems like this gave me a little more modulation with my throttle stick. Not sure if this is a best practice or not. I am going to switch it back when I feel more confident.

I am still improving though. I was able to rotate several 360s (slow) while hovering and for the first time I was able to steer the heli where I wanted it to go instead of just being reactive and correcting flight the whole time to keep it off the walls of my garage. LOL. I am surprised on how much more difficult this is to fly than my 4 channel flybar heli but I will be there soon enough.

Thanks for the help so far.

Shawn

[The Mechanic]

Flying in normal mode with a collective pitch heli can be tricky. The blades are thin, symmetrical and made for constant speed. You might be better off changing the normal mode pitch curve so the pitch of the blades doesn't move as much when you move the stick. If the speed of the rotor gets too slow it can be very hard to hold a hover. It really is much easier to hold a hover in idle up.

You haven't mentioned a flight simulator. Your Walkera transmitter (if it's a 7 or better; I don't know about the cheaper ones) will work with Phoenix Flight Simulator which I think is a good value even though it costs over a hundred dollars. You're really going to be climbing a steep hill without a sim.

[galaxy24]

Sorry for the slow reply I was having difficulties with the site.

I think I know what you are talking about. Towards the end of the throttle range (maybe 80%-100%) I can hear the motor RPMs drop, however, the heli will increase in altitude quickly. Sounds like the blade pitch spikes up during this throttle range. To be honest I don't really fly in this range until the batteries are getting low. I would like to smooth that curve out though. Is that what you are referring to?

I checked out the Phoenix Flight Simulator since you mentioned it. I am going to look into getting it, however, it wont be right now. I am going to keep playing with it for now. When things start to become second nature and I feel like it is time to go inverted I will purchase the simulator for sure. That isn't something I want to just jump into. I want this heli to last awhile.

[The Mechanic]

Yes; in normal mode the interaction between pitch and throttle has to be good or the angle of attack of the blades will get too close to a stall. It'll have a real mind of its own in that condition. Those super flexible thin blades aren't made for normal mode. I think you would be surprised how much more stable the heli is using a medium fast constant speed on the rotor and then all you're doing is changing the pitch of the blades.

One other thing I forgot is the transition from "chopping" the throttle to avoid a bad crash (which is what you might do in normal mode; to clicking the throttle hold switch which is what you do in idle up to avoid a bad crash. If you learn chopping the throttle you'll have to re-learn to hit TH instead. Just one more thing.

It sounds like you're doing very good. Your Mini CP would be pretty tore up by now if you weren't. Even with hours of practice on the sim I totaled my Blade Nano at least twice flying in the house. Once trying to fly inverted in the family room. I now keep it in pristine condition but I don't try inverted flight in the house any more. I flew it inverted out in the field one day and did pretty good but it kept wanting to wander away from me because I'm no good upside down. Still learning that.

[galaxy24]

I have been doing pretty good so far. I have minimal damage luckily. I am at the point now where I am rotating hovered 360s and focusing on just keeping in in as tight of a space as I can. I am also flying it across the property outside kind of like an oval race track. I wouldn't say it is pretty but I can get it done.

I would like to get that setup.

I tinkered with it a little bit yesterday. This is trial and error here since I am not sure on what I am doing.

I think this is what you are talking about:
I adjusted the throttle hold to 40%.

In my hand:
I moved the stick to 50%
Flipped the HOLD switch down
0-50% stick movement pulled the heli down
50-100% stick movement pushed the hell up

On the ground:
I set the heli on the ground and increased the throttle. It started spinning in a circle. That is about all I had time for so I put my settings back. I am guessing that there is an adjustment I need to make on the rudder to stop it from spinning. Just not sure what.

Shawn

[The Mechanic]

That sounds like you're doing pretty good. It's a lot of fun in the beginning when you can easily see your progress.

I have a Walkera transmitter but I use deviation firmware. I've never used the Walkera firmware and it's been over a year since I setup a model in a "conventional" transmitter like my Spektrum DX6i so sadly I can't give you a specific procedure.

It's not hard but it does take a careful study of the manual to see what they're trying to tell you; probably in broken English. The throttle hold will reduce the throttle to zero and shut off the motor no mater if you're in Idle up or normal mode.

The switch to change from normal mode to idle up 1 (or idle up 2 if you have it) is a different switch than throttle hold. The idea is to have about 50% throttle at mid stick (collective) in both normal mode and idle up so the switch from one to the other is seamless. It's perfectly OK to have more throttle at mid stick in idle up than normal mode (if you need more throttle in idle up).

You just start in normal mode with the collective stick down, slowly move it to about the middle, switch to idle up mode and then fly. When you land you hit throttle hold to shut off the motor. Bob's your uncle (there ya' go).