mglavin

My Feedback: (31)

All right then I'll have to ponder this all over...[sm=tired.gif]

Stick Jammer

Lets go back to the example of the full range of throttle rotation being 80 degrees. There are 26 possible throttle positions. If the "steps" of throttle plate rotation were all equal, they would be 3.077 degrees each. If the mechanics of the high ATV set up produces some of the 26 "steps" that are less than 3.077 degrees, it has to produce others that are more than 3.077 degrees for a total of 80 degrees rotation.

Shogun

My Feedback: (2)

You know I thought about this some more and I do adgree with the assertion that the degrees of arc movement would be similar for each throttle position of the detents on the stick.

But.....

This is not taking into account details like the time elapsed between the clicks like Crash was talking about, sorta like the difference in speed at a props tip versus a location closer to it's center, faster at the tip but slower as you get closer to the center. Remember we are dealing with motion in an acr and the distance plays a role in the final result, ot in this case control of the throttle blade in the carb throat. Also there are a few of us that don't use the detent spring in our transmitters so there are NO decernable clicks to compare the degrees of rotation between. All I can say is that this is one of those subjects that can drive you nuts if you think about it too long....

mikenlapaz

Interesting discussion.
What has not been mentioned is the amount of area that the butterfly opens with each of those '26' detents of stick movement for the total 80 degree rotation. I do not know the math, but the area in the mid range is unlinear. What does one click, 3 degrees rotation equate to area change around the butterfly? Would be interesting to know the percent area changes with each 3 degree rotation.

If I have understood correctly
1) First several degrees of servo arm is non-linear, more sidewise movement; First 20+- degrees of butterfly rotation opens only a small area compared to remaining 60 degrees rotation. ;
2) Greater ATV, as much as you can get, adjusting the linkage to get as much as practical, gains sensitivity in the radio aspect of this problem;
3) If you radio allows it would be benficial to put in some negative expotential (reduce sensitivity near the neutral center point of the servo) This should have the benefit of making the next 30 or so degrees of servo AND butterfly rotation similar to the first 20 degrees of rotation;
4) The radio portion is going to try and make up the reduced response near center by increasing the rotation on both sides of the expo adjusted center. (benefit to the first 20 degrees of very limited effect butterfly rotation.

Quality servo makes sense. At or near idle the engine suction on the butterfly trying to close it only re-enforces considering upgrading the servo.

Stick Jammer

With a very high ATV on throttle, both ends of the servo arm arc most likely will be more sideways movement, or non-linear. This will affect both the lower and upper portions of stick movement.

Negative expo on the throttle channel will make the stick less sensitive starting from the idle position and increase sensitivity as it is pushed up, unlike the other channels that are less sensitive around neutral (center).

Well, a quality servo is always good, but because the butterfly shaft is in the center of the throttle plate, there is equal suction on both sides. It cannot be sucked closed because the other half is being sucked open, it equals out.

Stick Jammer

Without a doubt, discussions such as this can start to make you a little wacky. On the other hand, they do tend to make you look at things from both sides of the fence, not a bad thing at all. As far as the smooth mode of throttle stick, it is entirely possible that you could have finer control, (once accustomed to it), over a radio that is limited to 26 clicks. For the most part though, it is unlikely that the smooth stick is ever moved at finer increments while flying, but it is possible. Even without the detents, the mechanics of the set up still apply. As far as the speed issue, that's probably a whole new debate of it's own! I would tend to think a faster servo would be better. When doing high alpha stuff low to the deck, the pilot's reaction time is already enough of a delay to overcome when a quick throttle adjustment is needed. Why make it even slower? Slow that reaction down too much and the plane is re-kitted!

Shogun

My Feedback: (2)

What I have noticed when using this technique, higher ATV with linkage adjusted to compensate for the increased travel, is a change in the overall " feel " of the throttle. It feels like I can really horse the throttle back and forth with better control over the midrange, without over doing it. I guess what I am saying is that the control is there like it is with a set up using lesser ATV settings but I can move the stick more without seeing an instant increase in rpm that comes in too fast to manage. This is very much the same feel as adding expo to a control surface that is overly sensitive with small movements of the stick.

Now I know you can do this with expo on the throttle but remember that there are a LOT of guys that have lower priced radios that don't offer expo on the throttle. I have a 9C now buy year before last I was using an Eclipse and even though it's miles ahead of most budget radios, it doesn't have expo on the throttle or a throttle curve for that matter. The linkage set up and ATV is all a guy in this situation has and while it's not as good as programming it can make a big difference in their control while in throttling maneuvers.

Stick Jammer

Giant Scale Aerobatic plane = time to get a decent radio.

Shogun

My Feedback: (2)

Oh I agree completely about that! ut you know how people are.....

And FWIW I guess I have been speaking in general this whole time, I have made use of this little technique on everything from foamies to GS planes with success.