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Aileron Differential and Flap problems with JR gear

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Doug Ireland11/11/2007 16:05:00
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Hi guys, I have a similar problem to the Handyman and did not want to clutter up his thread with my queries.

I'm using a JR 2720 and have set up the wing type as "flaperon"; so far so good and have equal travel on both ailerons. The Diferential is also quite easy to set up. My problem is when I try to set the aileron droop when the flap set-up is used. After a bit of faffing about I can get the ailerons to drop like flaps (which is nice) but when I waggle the stick the ailerons only go further down and up to neutral. I have not tried to fly in this configuration yet without some advice from my seniors.

Any advice greatly appreciated,

Handyman11/11/2007 16:19:00
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Hi Doug, join my thread with pleasure, two heads are better than  one, and your problem sounds very much like mine, when I was using the flaperon function on my ARC Ready.

The Futaba manual tells you all of the things to do, but I found things very similar to you. I did not dare to use the flap function until I was established on finals with my wings level, because as soon as I lowered flap, I lost my ailerons. All the movement that I could get was one or the other aileron lifting slightly, and that was all.

I have either got to purchase some more new gear, which I am loathsome to do, at my age, or build a new wing for the Ready, with separate flaps, and set the required differential mechanically as I have always done in the past.

Doug Ireland11/11/2007 16:29:00
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At least you had the nerve to fly! When I looked at the control movements with the kite on the bench... well.

There must be a way of getting normal aileron travel as well as using them as flaps.

Handyman11/11/2007 16:59:00
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As long as the flap control was turned off, everything seemed to be normal. the action of drooping the flaps/ailerons was when my aileron movement went all too pot, or so I thought.

I have an old Army friend who flew a DHC2 Beaver aircraft when we were out in Aden 1965-67. He tells me that whenever they lowered flap, the ailerons also drooped down as well, but not as far as the flaps did. He tells me that even with the aircraft set up like that they still had full aileron authority. with bags of drag and a pronounced nose-down attitude.

I think we are getting too demanding of our radio control equipment and not enjoying the flying more.

Doug Ireland11/11/2007 17:05:00
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When I was in the Airforce the F4K's that we flew had Aileron Droop as it was called but that was ok as the ailerons only went down; spoilers took care of the "up" bit.

You're probably right, we are asking a bit much! Would be nice if it worked though.

Handyman11/11/2007 17:08:00
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Thinking about that statement, if both ailerons are down an equal amount, and you introduce say a tad of left stick, the angle of the left flap/aileron will decrease, but the angle of the right flap/aileron/ will probably increase slightly.

Now, will this decrease drag on the left wing, but give more lift to the right wing, adjusting the angle of bank in doing so, or will the opposite happen. Mind you, the rudder tends to be more effective at low speeds, so perhaps that is the answer when we are using flaperons.

I rest my case.

Doug Ireland11/11/2007 17:20:00
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I use aileron/rudder mixing on all my models and it works a treat.

As I recall the last time I had my latest model on the bench. With the flaps down, a "right" stick input would not make the right aileron go down any further but would make the left aileron come up toward neutral. And vice versa. But as I said earlier, I've not tried it in the air.

Oliver Stecher11/11/2007 19:54:00
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Have you guys tried each servo on two different chanels and setting the end points for each servo's travel incorporating the differential you desire?

On my Futaba 14MZ, i have one aileron in chanel 1 and the other in chanel 6 ( Aileron 2 ) then set the end points of each aileron with the set differntial i like.. this is a good method as you can allways fine tune each side without interfering with the other aileron.

Oliver Stëcher

Doug Ireland11/11/2007 23:53:00
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Yep thanks Oliver, the set-up you mention is pretty standard for a 2 servo "flaperon" configuration but I think you missed my original query on this thread.
Doug Ireland12/11/2007 15:41:00
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hi Jetsome,

I've got about 15 degrees set as flaps out of the full 30 degrees available. My query is why the ailerons don't go above neutral?

Handyman12/11/2007 19:24:00
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Oh dear! what have I started here. Trust me, a new boy on the block and look what I go and do.

Oliver, your idea sounds fine, but on my gear ch1 = aileron, ch6 = flaps. So where do I go from here.

All I want to do, is to make sure that my upgoing aileron travels further than the downgoing one, which the good book says, "Might cause adverse yaw in the wrong direction, if differential is not used"

Does this really matter that much, will we suffer from the excess drag cause by the downgoing aileron, if they move the same distance as the upgoing one.

I think I am going to put the kettle on and study the manual again.

Doug Ireland12/11/2007 21:49:00
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Hi Jetsome,

Think I may have confused you a bit. The ailerons on my model are set 30 degrees in both directions, 60 degrees total so I have the flaps set at half down travel. The servos are set for 145% travel and I'm using 1" long servo arms and the aileron horn is 1 1/8" from surface to pivot point. Taking what you have said into account, I thought I would have had some upward deflection on the ailerons.

Handyman,

Normally, the left wing servo goes into the "Flap" socket and the right wing servo into "Aileron"; at least it is with JR

Julian Beckett12/11/2007 22:25:00
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4 articles

A similar problem as removing aileron differential under crow braking with a slippery F3f glider.

It may be that you're at the limits of what the tranny can do. You're probably looking at FF9/JR PCM9/MX22 and above to deal with these sorts of issues.

Go fishing for some glider boys - bet Mr Ellison could help...

Julian 

Julian Beckett12/11/2007 22:28:00
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Just checked out the spec of the radio - reckon you'll have to do some clever mixing with the free mixers to get around this...
Doug Ireland12/11/2007 22:33:00
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Rats, took me all my limited grey-matter power to get this far! Think I'll just forget it and rely on that bloody great 24" prop to slow me down! Thanks anyway Julian
Tim Mackey12/11/2007 23:17:00
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As I said in the original thread posted by handyman, it is probably just a case of the tr not having a differential facility within its programming capabilty. Even if it did, one is still limited by the maximum throw of the servo, and if you use all or most of that for the flaperon function, then there just isnt any left for ailerons as it were.
Gordon Whitehead14/11/2007 17:49:00
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I've used flaperon for many years on strip aileron planes using JR radio. 

 I set the mixing so that the ailerons only depress enough so they don't go down beyond neutral at full aileron deflection.  So if the ailerons have 15deg up deflection, the max flaperon depression I use is 15deg.

This still reduces aileron authority down to very little.  I counteract that by arranging for 100% coupling between aileron and rudder, with the rudder becoming slaved to aileron when full flap is selected.

I also always use 2-stage flap.  1/2-flap for turning finals, and only add full flap when the plane is established on the glide slope to land.  The rudder input isn't essential with 1/2-flap, but a bit mixed in is helpful.

Cheers

Gordon

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