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JR 8103 AND NEGATIVE DIFFERENTIAL

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Old 09-13-2004, 10:06 AM
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John Murdoch
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Default JR 8103 AND NEGATIVE DIFFERENTIAL

Hi All,
I was wondering if anyone knows how to set negative differential in the 8103 or if it's capable of doing it at all?
John
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Old 09-13-2004, 11:54 AM
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Rodney
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Default RE: JR 8103 AND NEGATIVE DIFFERENTIAL

Do you mean exponential? If so, different brands define negative exponential differently. Usually it means that you have to move the control stick more near neautral to get the same surface deflection that a little movement near full stick deflection causes. Another brand might define this as positive exponential . If you can adjust exponential on your transmitter, you should be able to go to either plus or minus at your discretion.
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Old 09-13-2004, 12:01 PM
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Default RE: JR 8103 AND NEGATIVE DIFFERENTIAL

No.. I mean negative differential.. On most planes, the aileron is centered within the wing area which means you get just as much surface throw equally, up or down. Now, with the Composite-Arf setup, the hinge is actually incorporated into the top of the wing/aileron itself which off-sets the throw. When you make the aileron trave up, everything is okay. Now, with down travel, the aileron actually sucks into the wing area which ultimately provides less aileron surface. The instructions say to set the differential at negative 10%. What this does is allow the downword aileron to add another 10% of travel which compensates for the lesser surface area that's sucked into the wing. Does that make sense?
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Old 09-23-2004, 11:19 PM
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Default RE: JR 8103 AND NEGATIVE DIFFERENTIAL

OK, what I did with mine is first, the ailerons have to be on seperate channels (I used ail. and flap). Mix the two together (I used prog. 6). Set the differential for the aileron channel in the travel adj. screen. Next, in Mix 6, set the travel "rate" for the slave (flap) channel to get your differential on the other side. That should give you what you want.

Gary Hunt
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Old 09-24-2004, 05:43 AM
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Ben Diss
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Default RE: JR 8103 AND NEGATIVE DIFFERENTIAL

Yes, the 9303 does negative differential. Theres a mix for differential and you set it to a negative value.
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Old 09-29-2004, 12:25 PM
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danfield4
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Default RE: JR 8103 AND NEGATIVE DIFFERENTIAL

Hello

Curious as to the plane in question and why this would be a problem. Most planes need Diff anyway and usually more than 10 %.
I would fly the plane first and check the diff, then see if you really need to do this. in fact your manual even shows how to set up the servo offset for mechancal Diff as well. look in the back under Practical Setups. You could also setup the servo linkage angle to gain more down if you must.

now,,, I don' t have my manual in front of me nor the plane, so somewhat talking out my left ear but you may be able to give this a try and see by fumbing around on your own.

I also don't know if your plane is full house or only Ailerons. If I plug in the servos exactly as the front page of the Glider section shows, everything works correctly except the Diff is reversed, meaning; as diff percentage is increased the UP going aileron goes down.

If I go by the Picture a few pages back, all is well. so, either a typo or a software bug in my radio.

point is, if this works to correct the problem, you may just switch the aileron channels, I think you then have to resverse the servos then YOUR diff should be reversed. give it a try and advise.

I have notes on the page to change the plug in order. ;-0

the ATV method will work also, but dificult to make changes to Diff while flying the plane.

regards
Dan Field

ORIGINAL: 232Cap-Tain

No.. I mean negative differential.. On most planes, the aileron is centered within the wing area which means you get just as much surface throw equally, up or down. Now, with the Composite-Arf setup, the hinge is actually incorporated into the top of the wing/aileron itself which off-sets the throw. When you make the aileron trave up, everything is okay. Now, with down travel, the aileron actually sucks into the wing area which ultimately provides less aileron surface. The instructions say to set the differential at negative 10%. What this does is allow the downword aileron to add another 10% of travel which compensates for the lesser surface area that's sucked into the wing. Does that make sense?
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Old 09-29-2004, 12:53 PM
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Default RE: JR 8103 AND NEGATIVE DIFFERENTIAL

Dan.. Thanks for the analysis.. You've hit every possibility to achieve what I needed to do. I've thought about each of your comments except for the angling of the horns. That would be so permanent and not very adjustable that I'll just kind of nix that idea.

I just did one thing better. Purchased a TX that has negative differential. There, wasn't that easy$$$$$

John
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Old 09-29-2004, 02:26 PM
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Default RE: JR 8103 AND NEGATIVE DIFFERENTIAL

Hi,

When I wrongly plug in both servos of the ailerons in the receiver (I mean left aileron-servo in right aileron receiver-output and vice-versa) I obtain what you can only obtain on very expensive transmitters : negative differential.
In my case, I then am not happy, because mostly I have to remove again the wing to switch both servo plugs.

Olivier
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