RCHubbub

I have both a DX-7 and x9303.

It seems to me that the graph shown in the exponential section of x9303 is reversed. I know it's reversed as compared to my DX-7. With positive exponential, the sensitivity around stick center should be reduced and on the graph the y-axis output should become flatter. It does on my DX-7. But on the x9303 it actually becomes more vertical which seems to be opposite of how it is described in the manual. Looking at the servo monitor, positive expo does provide for less servo movement from stick center as expected, but that's not how the graph shows it. Did JR screw up the graph function?

onewasp

IMO if you are using these displays for anything other than "eye candy" you are in for some spell binding flights.

Check the A/C (on the ground first) to see if it is doing what you want. Then fly it to see if you like the results.
The only thing that matters is flight performance.

I have zero idea where my sticks are during a flight as it is only the attitude of the A/C that matters.

Perhaps I've been flying too long.

AWorrest

My Feedback: (5)

Are you sure you are reading the X9303 graph correctly. As I recall the DX7 expo graph is only one-half of the graph the X9303 shows. That is, the DX7 shows the centered stick position on the far left while the X9303 center stick position is in the center. Otherwise, there is something wrong with your transmitter display. On my X9303 and XP9303, a positive expo will flatten out the center of the curve.

Allan

rmh

...

onewasp

No, he is right on the two graphs, at least mine, show it exactly as he has written, DX7 vs. X9303.

It depends on how you view the graph - each is correct - simply put the DX7 seems to picture the servo output resulting from the application of + (JR) expo. This puts the curve below the diagonal.
My X9303 shows it above the diagonal it is the same thing, different viewpoint

Either way it is still "eye candy".
It shows a vast generalization. The only quantitative measure is the A/C's flight attitude and response to control input.

Put another way, take the numbers over the graph every time.
But then make certain you know what + and - are as JR and Futaba view this from opposite directions.

RCHubbub

The graphs are the same between the two which is weak at best. They both just show "Output" on the y-axis and nothing else.

But I think you are completely correct on how they plotted them. The x9303 does seem to plot the curve with the stick at the center, and the DX-7 seems to plot only half the curve starting at the bottom left. Looking at it that way, then it all makes sense, and I would have to say the x9303's plot is better than how the DX-7 does it.

Thanks

edit

Actually thinking about it more, the DX7 was my first radio, and I understood quickly what expo did looking at the DX-7 graph that I don't think would have been so readily picked-up on if the 9303 had been my first radio. So, I think my preference for one plot versus the other is probably tied to my experience level at the time.

Howard

My Feedback: (55)

I believe you are interpreting the JR 9303 curve such that y=0, x=0 is at the bottom of the curve (lower left corner) when that point on the curve is really half way up the displayed y axis and half way to the right on the x axis. If you view that point as the y=0, x=0 and dial in + expodential you will see that both the + and - values for y are diminished about for both + and - values of x, which is what is suppose to occur. I don't think the curves are just eye candy - they show you graphically what you are changing. I do think the numbers can be misleading except to understand that bigger is more.

Howard

AWorrest

My Feedback: (5)

The X9303 expo/rate display shows the curve from one stick extreme position to the other because it is possible to adjust the rate and expo for the left of center stick position independently from the right of center. It's been a while since I owned a DX7 but I don't believe it had that capability.

Allan

onewasp

Couldn't agree with you less Howard.

Just how does (at best) a 'representative' unquantified graph of approximately 1.5" square 'G' with a numerical percentage of control throw which is a known in both degrees of deflection and in linear measure of the TE movement?

It doesn't.
Unless all you want is a nice graphic representation of what you have dialed in.
Not a single measure. How does that begin to compare with percentages of a known factor?

I have used degrees forever.
Chip Hyde says he prefers linear measurement of the TE.

Either way it is far closer to exact than the "near about" indication you get from the graph.

Did you have a bad day or am I missing a major point in your argument?

Howard

My Feedback: (55)

It must be a challenge to be pompous and arrogant while keeping an open and understanding mind - yes, you certainly did miss the major point. The TE movement is the algebraic sum of two separate sinusoids plus the exponential curve displayed on the 9303 and knowing what the input curve looks like is very helpful - regardless of whether you understand it. I am glad you and Chip are so close.

RCHubbub

For me the JR graph sent me down the path of potentially getting in trouble. As I looked at the graph, and being only familiar with the DX-7, it looked like positive expo was opposite of what I was used to, so I ended up dialing in -40% expo. But on hindsight, I do remember thinking the curve still looked funny how it started out flat and then climb, and then mid way through the stick movement it would flatten out and then climb again. I thought that was odd, but still pressed on. And just eye balling the control surfaces movement and such, it was not readily apparent that I had done the opposite of what I intended.

The x9303 being a new radio for me, I had no plans of actually using it until I finished the manual. When I read the expo section, I realized what it described is how I understood it, then I knew my interpretation of the graph or something else was wrong. I easily confirmed this through the servo monitor and corrected it by putting back in +40%. I used the graphical representation for really no more than just that, but it could have screwed me up because of my previous DX-7 experience.

onewasp

{Quote}
It must be a challenge to be pompous and arrogant while keeping an open and understanding mind - yes, you certainly did miss the major point. The TE movement is the algebraic sum of two separate sinusoids plus the exponential curve displayed on the 9303 and knowing what the input curve looks like is very helpful - regardless of whether you understand it. I am glad you and Chip are so close.
{Quote}

Ahhhh, but ONLY if one has your background or one similar to it.
For the rest of us it is how the A/C flies. And it is easier to interpret a % of degrees or TE measurement than that which you suggest.

I am a Philosophy, Political Science (+ two) major with a BA. While I traversed the courses through differential calculus it is something I never cared for and have long since discarded as usable or desired by me personally.

Re reading your post I will graciously define it as bad day for Howard.
That seems justified particularly since we are discussing toy airplanes and the Tx display thereof.

onewasp

RCHubbub

Glad you caught it before an unpleasant surprise airborne.
That the definition of positive expo differs 180 degrees between JR and Futaba is a bit disconcerting particularly if you are not ready for it (aware of it).

van-c

As can be seen on page A-54 in the manual, the center of the graph corresponds to the "neutral point", i.e., with the stick centered. In the figures in the manual, because of the horizontal and vertical axis lines, it is a little clearer that the center of the graph vertically corresponds to "zero" output and that output deflection (vertical axis) is either positive or negative (up or down, left or right, etc.) as the stick (horizontal-axis) is moved from the neutral point. The graph displayed on the Tx screen is not so clear, however, partly because of absence of the axis lines.

Van

Howard

My Feedback: (55)

Van,

Much clearer way of saying it than I did - I wonder if the new 12X will have the center (0,0) marked on the TX screen, that would make it much easier/clearer to the user.

Howard

van-c

Probably one reason they omitted it in the X9303 is the rather low resolution of the graphic display. The origin or axis lines might just clutter the graph, since the exp curve would pass so close to them. I don't know if the 12X display is higher res; it does have a backlight, though, which would be very helpful when "couch flying" the Tx.

BTW, I thought your description was very clear; corresponded exactly with the figures in the manual.

Van

FLYBY12

My Feedback: (14)

Hello, I was directed by my local hobby shop to dial 40% pos. exponential for a smoother feel of my 9303. I have always flown with no ex. dialed in will this 40% give me a smoother control?

pilotpete2

Yes, it certainly will tame down the sensitivity near the center of the sticks travel. Try setting that percentage and watch the control surfaces carefully, you'll get an idea of how it will affect the sensitivity around center stick. I'm a Futaba guy, and usually start with 25% expo, which is not all that much, very subtle change.
Good luck,
Pete

FLYBY12

My Feedback: (14)

Thank you!

BarracudaHockey

My Feedback: (11)

Try what you like, it won't explode. Some people like more, some like less.

BuschBarber

My Feedback: (2)

I have a couple of 9303's. Be sure to use + numbers to soften the sensiticity around Neutral., for JR/Spektrum radios. The amount of Expo depends upon the amount of travel. Low rates use lower Expo. Higher rates and higher Expo.

Be careful not to use too much Expo. If it is too soft, you will have to bang the sticks