G7703D - X9303 D/R programming question..!

[huskynox]

So, in the G7703D manual there're some setup examples - for example a Trex 600E with a 8900G servo. It give recommendations for arm length, gain, ATV's, D/R, and expo.

My question is what does D/R do...? In the D/R - Expo menu I can see that Expo softens up the center of the curve and D/R appears to soften up the ends of the curve. I alway thought D/R's shortened the ATV's when I hit the switch, but when I hit the Rudder D/R switch it doesn't do anything as far as servo travel.....?

So what I'm thinking is, D/R's on the rudder channel soften up the stops? Anyone an expert in this area?

Thanks!

[Youngblood]

You are absolutely right the way you are thinking things work.

Think about this for a minute - If when you were learning to drive and someone put a limit on the gas going to the engine to 75% would that help? Same gas pedal travel but you could only get 75% fuel to the engine. You probably never passed anyone and went pretty slow anyway (just flying around and landing) Then as you got more experience they removed the block and you had all the power available (flips, rolls, and 3D). Sometime you don’t need it all and limiting things might help a little. I use 75% on just about everything for FAI style flying and 100% for 3D.

This is how I look at things for example the elevator channel:
The stick on your transmitter is mechanically set for a certain amount of travel and it can't be changed. So, if I set the dual rate to a 100% the stick moves from the bottom to the top utilizing all the servo travel. Now I set the dual rate to 75%. The gimble on the transmitter moves the same amount but the servo does not. Same amount of stick movement but less actual servo travel yielding a little finer control. You could set the expo and possibly do the same thing but when you reach the limit of the expo you get a big jump. 75% travel 20% expo 100% travel 35% expo.

I use a HH gyro on the rudder and want the tail to hold solid so I never use dual rate or expo on the rudder.

Charles

[huskynox]

Hi Youngblood,

I understand your analogy/description (I think), but what you've described is a typical D/R example. I understand that the stick still travels 100%, but with say 75% D/R the servo only travels 3/4 of what it would normally travel with D/R off.

What I'm saying is, when I flip the D/R switch on the rudder, the servo travel does NOT change. The tail blades move the exact same amount.

Here are the numbers JR gives for an example:

8900G - 11mm arm - 75% gain - 150% ATV - 80% D/R - 50% Expo

Again, when I flip the D/R switch for the rudder, the servo travel remains exactly the same with full rudder stick input. The tail rotor blade pitch does NOT change at full rudder input.

[Pinecone]

Realize that stick movement translates to piro rate, NOT servo/tail travel.

The gyro will try to make the tail move at a given rate with a given stick motion, but on the bench, the heli doesn't move, so the gyro adds more pitch to try to get the right piro rate.

In flight it won't do that.

D/R is like Youngblood says, by setting a lower dual rate just limits how uch stick trael is transmitted to the gyro, thus limiting the piro rate.

[huskynox]

Realize that stick movement translates to piro rate, NOT servo/tail travel.

The gyro will try to make the tail move at a given rate with a given stick motion, but on the bench, the heli doesn't move, so the gyro adds more pitch to try to get the right piro rate.

In flight it won't do that.

D/R is like Youngblood says, by setting a lower dual rate just limits how uch stick trael is transmitted to the gyro, thus limiting the piro rate.


Now that kinda makes sense! Thanks Pinecone (and Youngblood) for your responses. BUT, that's getting into the black magic of the gyro circuitry, which is above my head..... I'll have to flip the D/R switch to see what happens while doing piro's.

[Youngblood]

The last guy is exactly right.

I misunderstood the question a little and took a few things for granted that I thought you knew. You never mentioned what gyro you are running. No matter what the radio says the GYRO can drive the tail to do what you describe. The ATV's should be set on 100% both directions. The travel for the rudder is set in the Gyro. Example: 401 you can set the travel with a small pot on top of the gyro. The 611 you can set both directions at a screen. I am a little leary about the settings you described. I never set rudder for anything but 100% and never use dual rate or expo on the rudder. Please look at Finless' Video’s on setting up the type of gyro you are running. He explains arm lengths and why everything does what it does very well….

I can see you are doing the right thing. Search for the answer and don’t STOP until it makes sense to you. There are a lot of way's to set things up and guess what they probably all work.

Charles

[bullaculla]

I have that same gyro and tail servo and set it up per manual on my stretched 600. The tail holds rock solid but the stick is pretty numb at center. I lowered my gain, and lowered the expo and D/R slowly to a point where I feel comfortable. Very good gyro and servo! :thumbup: