DX6i Settings for the SR?

[cedron]

Is Finskeeper the only one of a few that are going to share their settings? Come on everyone post your settings or variations of the one I posted and tells what you think good or bad. It will only serve to help us all in the long run!

[EvilSmirk]

I'm using your settings exactly as you have them Cedron at the moment. I'm going to try Finskeeper's settings in the next few days and see how it plays out. I do find that I like between 70% and 75% for my gyro gain, which matches about where I was on the stock TX channel 5 pot as well. I'm going to match a blade pitch to your pitch percentages soon and start with a -10 to +10 head setup the next time I go through a rebuild so that I have more authority when I switch to Idle Up, but since I'm a little nervous hearing that little heli scream, I'm hesitant to do so.

[Digger66]

Can anyone post their settings? As I will be using Cedron's settings, but would like to know what & why other fliers are using.

[EvilSmirk]

I have stumbled across a problem and wonder if you guys can help me out. I've heard a lot about how increasing the head speed of our beloved SRs will help with stability and response. The obvious switch to get used to that in a hurry is to throw the heli into Idle Up and clench your cheeks. Not wanting to really go through that, or go through and resetup the head until I need to, I figured I'd increase the head speed slightly, which would require a decrease in blade pitch to give me the same lift at a given stick position. I need someone to check my sanity and my math since it's been a long time since I've had to use this stuff, so here goes.

The lift equation, as I understand it, is...
L = (1/2) Cl * r * V^2 * A where
L = Lift
Cl = Coefficient of Lift = 2 * pi * theta (for a thin airfoil and theta is in radians)
r = Air Density
V = Velocity
A = Blade Area

Here is my thought process, equate 2 lift equations together, drop the constants, and go from there...

(1/2) (2 * pi * theta1) * r * V1^2 * A = (1/2) (2 * pi * theta2) * r * V2^2 * A

Removing the constants gives me...

theta1 * V1^2 = theta2 * V2^2

Finding theta (using Cedron's settings at midstick and trying to find the correlated throttle value with a given reduced pitch (40% in this case))...

thetamax = 10 (pi/180) = 0.175 radians
theta1 = 0.175 (.5) = 0.087
theta2 = 0.175 (.4) = 0.070

Finding V1 at midstick and assuming that RPM at 100% equals 2000 RPM (the actual value of which really doesn't matter since we're comparing two percentage values when I'm done)...

Vmax = Cr * RPM
Cr = rotor circumference = pi * d = pi (21.8/12) = 5.707 ft
Vmax = 5.707 (2000) = 11414.453 fpm

V1 = 11414.453 (.6) = 6848.672 fpm

Here we go...

theta1 * V1^2 = theta2 * V2^2
0.087 (6848.672)^2 = 0.070 V2^2
V2 = 7635.139 fpm

V2 = Cr (RPM2)
RPM2 = V2 / Cr = 7635.139 / 5.707 = 1337.855

V2(%) = (1337.855 / 2000) * 100
V2 = 66.9% = 67%

So, if I want to decrease the pitch of the rotor at midstick from 50% to 40%, but maintain the same lift, I need to increase the throttle curve setting at midstick from 60% to 67%.

Does that make sense to anybody?

[singingperry]

I did Cedrons settings on a windy (12mph with gusts) day and loved them so much I got real cocky and got it above the tree tops where the wind just simply overpowered it! Beat the hell out of my B400.

[EvilSmirk]

Does my math or reasoning make sense to anybody? Or am I way out in the weeds without a map or a compass?

[Mojappa]

I think more people on here, myself included, go on a trial and error basis or Tx settings. Honestly your math, while impressive that you are that smart, bottles everyone else's minds. I think it's way too complex when you could just try out various changes, noting the results to get it how you want it. It's not like it'll explode if your setting are off, just won't lift at the right spot on the collective. Really just suck it up and flip that switch. It doesn't make it a rocketship wildly out of control win every little input you make on the cyclic. It's a little more responsive, a little more stable and predictable and actuall possible to fly in some wind. I was nervous the first time I flipped it and then felt kinda foolish for being afraid of it, like being scared of the dark, you realize there's nothing to fear and get a little more hair on your chest.

[William James]

Originally Posted by EvilSmirk

I have stumbled across a problem and wonder if you guys can help me out. I've heard a lot about how increasing the head speed of our beloved SRs will help with stability and response. The obvious switch to get used to that in a hurry is to throw the heli into Idle Up and clench your cheeks. Not wanting to really go through that, or go through and resetup the head until I need to, I figured I'd increase the head speed slightly, which would require a decrease in blade pitch to give me the same lift at a given stick position. I need someone to check my sanity and my math since it's been a long time since I've had to use this stuff, so here goes.

The lift equation, as I understand it, is...
L = (1/2) Cl * r * V^2 * A where
L = Lift
Cl = Coefficient of Lift = 2 * pi * theta (for a thin airfoil and theta is in radians)
r = Air Density
V = Velocity
A = Blade Area

Here is my thought process, equate 2 lift equations together, drop the constants, and go from there...

(1/2) (2 * pi * theta1) * r * V1^2 * A = (1/2) (2 * pi * theta2) * r * V2^2 * A

Removing the constants gives me...

theta1 * V1^2 = theta2 * V2^2

Finding theta (using Cedron's settings at midstick and trying to find the correlated throttle value with a given reduced pitch (40% in this case))...

thetamax = 10 (pi/180) = 0.175 radians
theta1 = 0.175 (.5) = 0.087
theta2 = 0.175 (.4) = 0.070

Finding V1 at midstick and assuming that RPM at 100% equals 2000 RPM (the actual value of which really doesn't matter since we're comparing two percentage values when I'm done)...

Vmax = Cr * RPM
Cr = rotor circumference = pi * d = pi (21.8/12) = 5.707 ft
Vmax = 5.707 (2000) = 11414.453 fpm

V1 = 11414.453 (.6) = 6848.672 fpm

Here we go...

theta1 * V1^2 = theta2 * V2^2
0.087 (6848.672)^2 = 0.070 V2^2
V2 = 7635.139 fpm

V2 = Cr (RPM2)
RPM2 = V2 / Cr = 7635.139 / 5.707 = 1337.855

V2(%) = (1337.855 / 2000) * 100
V2 = 66.9% = 67%

So, if I want to decrease the pitch of the rotor at midstick from 50% to 40%, but maintain the same lift, I need to increase the throttle curve setting at midstick from 60% to 67%.

Does that make sense to anybody?

[William James]

I am very fortunate to be friends with a man who really understands RC helicopters and also how to teach new pilots. (He's also a commercial flight instructor)
We put together these settings for the SR and he flew it in a 3 cubic foot area in his driveway in the squirreliest 25mph gusting winds I could imagine.
Here they are:

D/R E
100...-100
100...-100
100...INH

gyro sw-gyro
60

Throttle
0/25/50/75/100

Pitch
0/36/55/71/100

Swash
60/60/-35

REVERSED
rudd
pitch

Swash
ccpm 120

dr combi
FM

These were modified from Cedron's settings, so thanks to you for the basics stuff. Now he did say he liked the response from the expo being at -100%, but he would recommend decreasing it to about -75 or -80 for me.

Hope this helps,
-Will

[Rikybo]

Will,

Is that with stock blades and weights??

R/B

[William James]

Stock as it can be with the exception of the 400 main.
-Will

[Rikybo]

Gotcha,

Thanx for the settings......will give them a whirl!

R/B

[EvilSmirk]

Originally Posted by Mojappa

I think more people on here, myself included, go on a trial and error basis or Tx settings. Honestly your math, while impressive that you are that smart, bottles everyone else's minds. I think it's way too complex when you could just try out various changes, noting the results to get it how you want it. It's not like it'll explode if your setting are off, just won't lift at the right spot on the collective. Really just suck it up and flip that switch. It doesn't make it a rocketship wildly out of control win every little input you make on the cyclic. It's a little more responsive, a little more stable and predictable and actuall possible to fly in some wind. I was nervous the first time I flipped it and then felt kinda foolish for being afraid of it, like being scared of the dark, you realize there's nothing to fear and get a little more hair on your chest.

Boggling everyone's mind was not my intention. While I do understand what you are saying, I've had issues with unpredicted altitude changes when flipping the switch. Carrying over my example with Cedron's mid-stick settings, a 10% increase in throttle settings gives me this:

Throttle -> 0-55-70-85-100
Pitch -> 0-31-36.5-58.5-100

And the results are favorable. I feel the increase in the head speed has increased the response and made the heli more stable, while being able to see the same amount of altitude response as noted with the previous settings, though making her a bit more punchy given the increase in head speed, which is expected.

Definitely need to just get over it and flip the switch, but I think I'll hold off till I need to setup the head with a linear -10 to +10 pitch in Idle Up.

[crash 76]

Cedron thanks for the setting i had my first successful hover with my dx6i. compared to the factory controler.

[cedron]

Congratulations!

[DKS_ONE]

Thx for posting those settings cedron, definitely a big help for someone just diving into a programmable Tx. I was gonna try and sort it all out on my own (it helps me learn better) for as long as I could before I got frustrated. Never got the swash mix figured out, always had servos operating backwards What my question is is why does the one mix (pitch I think?) -35 while the others are -60? I think more so than the values, what they physically represent is what messed me up. I had all at -60 which got my pitch travel to function properly but then aileron was backwards. So I would reverse aileron and pitch servos and then all would be good with Aileron but then Elev would be reversed. Long story short, I eventually got to a big circle where I realized that there was no way to get everything to work correctly. I read your settings and couldn't understand them but said what the heck, put them in and all was fine! So I just don't get it, maybe I'm slow on the uptake but I thought that the swash mix just set servo travel...? If you have one servo at -35 versus the other 2 at -60 my logic suggested they would move differently but my eyes tell me otherwise!! lol, what do these values physically represent? Do the values of one setting effect the physical movement of the other two if changed (ie: are they percentages of one another's travel)? Just trying to understand it better...

[cedron]

Ok the best way I can explain it is this, look at all the servos all three in different locations and mounted differently, so two servos will travel a different distance to the third servo. to maintain a level swash. Anyone out there help me if I am wrong on this.

[DKS_ONE]

Originally Posted by cedron

Ok the best way I can explain it is this, look at all the servos all three in different locations and mounted differently, so two servos will travel a different distance to the third servo. to maintain a level swash. Anyone out there help me if I am wrong on this.

I thought that MIGHT be it, but wasn't sure. That said, Two of the servos face the same direction while the third is opposite. I could assume that's why two are + values and the third is a - value. But, why the difference in the actual value itself? I would have thought it should travel the same? Is that essentially what the swash mix does though? Control the throw of the servo arms?

[cedron]

Not sure about the values but lets look at the linkages. Two are relatively the same length and the third quite a bit longer. So I assume that is the reason for the difference in the values.

[DKS_ONE]

That is definitely a possibility, didn't think of that. Cool.