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JR XG 11 Programming Challenge!

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Old 08-05-2016, 12:05 PM
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barnowljenx
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Default JR XG 11 Programming Challenge!

Hi, I'm trying to set up my aerobatic biplane to have more aerodynamic braking on the downline and I've seen just the mix that might work. When the throttle is fully closed the ailerons on the top wing both go up while those on the bottom wing both go down. I would like to retain roll control as well while in this state.

I've looked at the programmable mixes and the stick position switch operation but cannot figure out how you control the four servos that drive the ailerons independently.

Has anyone overcome this challenge? If yes, how did you do it?

Thanks.
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Old 08-05-2016, 11:45 PM
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Quique Somenzini a few years back showed how to accomplish this on his Beast biplane using the JR 12X. He used the 4-Aileron wing type and swapped the left and right aileron on one wing while leaving them in their conventional locations on the other wing. If you download the 100cc Beast manual and look under the Crow setup, you’ll see how he did it.
 
His scheme works because all servos rotate in the same direction with an aileron command if none of the channels are reversed. So it makes no difference whether a particular servo is located on the upper or lower wings or on the left or right side as long as all the servo arms point away from or toward the fuselage and all the control horns are on the same side of the ailerons. With this standard setup the ailerons will always respond correctly regardless where they are put. However, with a flaperon command the left and right servos rotate in opposite directions. So if you swap the left and right aileron servos in either the upper or lower wing, a flaperon command will deflect its ailerons in the opposite direction of the other wing ailerons.
 
So all you have to do is:
(1) Set up a 4-Aileron wing type.
(2) Make sure the FLAP [OUT] in the DEVICE SELECT is set to SYS
(3) Set up a SPS that is on with low throttle.
(4) Set up the FLAP SYSTEM menu in the Function List.
(5) Set up a program mix of FLAP > FPRN. Include the FLAP SYS in the master FLAP channel. Set the POS0 rates to zero. Set the POS1 rates to 100%. Set three switches in the SW SEL to ON: the SPS, AND, and the FLAP SW position for the crow to take place.
(6) Swap the left and right aileron servos on one wing.
 
In Quique’s setup, the crow is activated by a switch. To have it come on when you idle back makes it more complicated and riskier. I would assume you wouldn’t want it to occur every time you throttle back. That could be disastrous on a landing approach! While the steps above ANDed the FLAP SW and the stick position switch, it is still risky. It is too easy to forget to disengage the crow by flipping off the FLAP SW after you pull out of a dive because the throttle had been advanced enough to turn it off .
 
I would recommend you scrap the idea of activating the crow with a stick position switch and just used the FLAP SW to turn it on and off. That isn’t fool proof but it would be safer than tying the crow to your throttle.
 
Allan
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Old 08-07-2016, 01:23 AM
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Hi Allan

Many thanks. As ever, you are a never ending fount of wisdom on programming the XG11!

Couple of additional questions before I set to on the programming.

Do I need to use the FLAP SW or could I use another switch. Currently, I use the ELEV DR switch to activate a downline mix to give a small amount of down elevator for a vertical downline. I switch this out for landing so using this switch to activate the crow braking would be good but I could live with the crow brakes activating on closing the throttle for landing as the aircraft does float if you arrive with a tad too much speed.

I have an idle setting for the electric motor for landing for which I use the THROT CURVE. Will this effect the SPS function. I think not but I'm not sure.

Many thanks for your helpful advice.

Peter
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Old 08-07-2016, 02:00 PM
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One thing to be watchful when you use the Beast wing setup is that aileron attributes may not work as expected if the servos don’t move exactly in the same manner. For crow on a biplane using the flaperon attribute, this is what you. But differential should also be affected. I believe that on the wing where the left and right aileron servos are swapped, the differential will be reversed. Quique didn’t use differential on his Beast. You should be able to download the Beast manual on
http://www.horizonhobby.com/pdf/1672...ast_Manual.pdf
 
Crow uses the FLAP SYSTEM menu in the Function List. You can pick any switch as the controlling switch by going to the DEVICE SELECT and on the right side of the menu choose the switch you want for the FLAP [DEVICE]. By default in the FLAP SYSTEM menu, position 3 for the FLAP [DEVICE] switch is set for 100% down flap. You’ll want to reduce that so you have some aileron movement free for roll control. You can also make changes in the menu so the crow is activated for the switch position you want to use.
 
Don’t make the same mistake as I did. The program mix to get the ailerons to work as flaperons on a 4-AILE wing is FLAP > FPRN not FLAP > AILE.
 
I don’t use the throttle curve. The few times I did, it made the throttle response worst. As near as I can tell, a switch position switch on the throttle stick is controlled solely by the actual stick position.
 
Allan
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Old 08-08-2016, 10:14 AM
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Allan

Thanks for your detailed input. I have now completed the programming of the Tx. You were right about swapping two aileron servos on the same wing and as I don't use differential there is no additional problem introduced.

I have allocated the Gear switch to activate the crow braking in conjunction with the Throttle stick and Flight Modes. I intend to fly the model to check that the crow gives me the braking I am seeking on the downline and to check whether I need to mix any elevator with the crow operation to maintain a vertical downline. I'm using FM0 and FM2 as well to activate the crow (with Gear selected up and Throttle fully closed) . FM1 is designated Landing mode so the crow is inhibited then. Once I've checked the flight characteristics, I'll move the Gear switch function to the Elev DR switch which I use to introduce some down elevator with fully closed throttle for flight. This switch is always selected OFF as part of my pre-landing checks so that will prevent crow operation as well as selecting FM1. I think that covers all the points you raised.

I'll post again once I've flown, but thank you once again for your help in sorting out this matter.

Peter
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Old 08-15-2016, 03:03 PM
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Hi Allan

I've now flown the aircraft, a Citrin, and the crow works well. As I said, the idea was to slow the aircraft on the vertical and 45 deg downlines. The initial test showed that activation of the crow resulted in a strong pitch away from the canopy and so I mixed some up elevator with the SPS. It took two goes to get a truly vertical descent. I then went on to try it when flying the schedule and it all worked very well with the downline speed now the same as my selected level speed. The only issue was that with the crow deployed the aircraft was relluctant to spin, so I shall have to remember not to close the throttle fully - this doesn't matter as the motor cuts off well before the throttle is fully closed and I want the crow brake to function as soon as I come out of the spin.

So, once again, many thanks for sorting out the programming issue.

Peter
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