splais

My Feedback: (25)

I read in another post were someone recommended splitting a dual servo aileron as a solution to the dual servo matching problem. I got to thinking about it and remembered the Giant Ultra Stick I had that had split ailerons that allowed you to fly "crow" and use flaps with it. That got me thinking. for the life of me I can't think of a reason that splitting each aileron in half so that each servo works independently is not a good solution; especially if you have a programmer and can match the speed, etc, of each section. PLUS, now you could program crow, flaps, etc in the 35% Edge I'm building. The only down side I can see is the number of channels you would need (to many to make it practical). then I got to thinking. Run two receivers and two batteries with half the surfaces on each receiver. Double redundant safety and the ability to do the Crow and Flap thing. Because I have a programmer I could also cut down on the number of channels by using Y's on the ailerons and programming each servo separately.

I'm sure some of you would love to comment on this. I've never seen it discussed anyplace before.

Tired Old Man

My Feedback: (1)

There's no reason not to try it other than for a complete lack of scale. If you're not going to use the plane for IMAC, then why not?

Volfy

My Feedback: (23)

I suggested doing this in one of the thread in the Mike McConville forum, and Mike said he didn't like it. He didn't go into great length explaing why not.

I agree with Silversurfer that the only real downside is non-scale appearance. Other considerations are:

1. Some TX don't have the same resolution on all the channels. So if you put all the servos on separate channels, ch 1~4 may have 1024 and ch 5~8 may be 512. I don't remember which TXs are like this, but I do know some are.

2. Each of the TX channels are updated sequentially, so if you have an older TX with a slower CPU clock rate, the four wing servos may not move all at precisely the same time.

But really, this is splitting hairs. I doubt too many of us can actually tell the difference. I've got a few ARC giant scale aerobats NIB and I might just split the ailerons on one of them, especially if the wing-loading is very high. Having a "flaps" mode might come in handy.

sillyness

My Feedback: (25)

I THINK that with JR, the first 8 channels are full resolution and the last 2 are half res. The Multiplex Royal Evo 12 channel has full res on all channels in 12 channel mode, but you need to use their IPD RX because there's data compression involved. Never used a Futaba.

If you put Ys on the Ailerons you wouldn't be able to do crow or flap mixing. If you Yd the outboards together they'd always move in opposite directions. If you Yd the inboards, the same. If you Yd the servos together in each wing half, one servo would always follow the other.

You could do:
Throttle
Rudder
Elevator1
Elevator2
Aileron1
Aileron2
Flap1
Flap2

You can make the low res channels choke and smoke if you're so inclined.

You wouldn't NEED 2 RXs... they would just be for redundancy. It would basically be set up like a sailplane, except you'd have a throttle instead of spoiler. If couldn't tell, I did this years ago on an old Ultrastick with a JR 8103 radio. Worked great.

ptgarcia

My Feedback: (36)

I was able to do the same with my Futaba 8uafs with 8-channel receiver on my 60-size Ultra Stick a couple years back. I had flaps and outboard ailerons, flip a switch and I had "crow" with outboard ailerons still able to work as ailerons, and with another flip of the same switch (I used a 3-position switch) I had full span ailerons. With a 9-channel setup you could still operate a choke.

3D ONdaEDGE

My question is why?. If you have a programmer, then you wont have a problem setting up the servos anyway. But your reall problem lay with the y-harnesses. If you Y the ailerons together, then you are cancelling out the whole reason to go with a split section anyway. You would have to plug the ailerons into different channels for say both ailerons to go up or down while the flaps do the opposite. The way you are tlaking about setting it up would be no different than setting up flapperons or spoilerons. You mighty get a little more aileron authority, but it probably wouldnt be enough to justify it. With all that said, I still think you ought to try it, just to prove me wrong. I just wanted to say what I thought would be the case if you set the plane up the way your are talking. Good Luck with it.

mikerc

My Feedback: (11)

I think it would look stupid on a nice Edge 540. My 2 cents.

dirtybird

My Feedback: (5)

I was told this was illegal for IMAC competition. Otherwise it seems to be a good idea to me.

Diablo-RCU

My Feedback: (1)

I can't think of a reason it would not be legal for IMAC. You don't have to have scale ailerons.

3D ONdaEDGE

No the control surfaces arent scale, but I believe there is something about adding control surfaces or something. Ill check it out.

splais

My Feedback: (25)

Wow, lets not start to get a little heated up on this one. If was just a retorical question to begin with. I had a brain fart and forgot about the scale issue; and the Y thing is out for Crow and flaps. When I got to thinking about it I then decided that: do I wanted to try the same goofy stuff I did with a $200 UltraStick, on a $3000 Edge! But if a person was not doing IMAC it would be an interesting experiment in flight dynamics.

I got thinking about this split aileron thing after reading tons of stuff and talking to lots of people about digital servo failures. I'm 90% convinced that 90% of those failures are due to improper servo matching no matter what people say. But lets not start that argument here please.

Got to read some of the above and see if I can get full features out of a 9 channel receiver and 10 servos, two batteries and two C-Volts

OnTheEdge

Simply having split ailerons is not illegal in Imac. I've seen a few planes at meets with split ailerons. You just cannot use the crow or flap feature during the competition (including freestyle). Just leave them mixed to full span ailerons and you're fine. I believe the way the rule is written, if the full scale plane had the feature (i.e. flaps, retracts etc), then you could actually use them.

On another note, in Sillyness's channel line up, you could save one channel by using a "Y" and programing the elevator servos, thus saving a proportional channel for a choke or smoke system.

........Mark

OnTheEdge

Here's Stepen Faust's gorgeous Carden Extra with split ailerons. Not sure if he uses flaps or crow or just does is it for servo matching.

catfish2

My Feedback: (43)

Splitting ailerons may be a good idea just to alleviate or reduce one problem. What happens when your "matched" servos suddenly decide to become "unmatched"? I saw this happen a couple of weeks ago, in our case the bad servo forced the surface to full defection. Plane and servos are less than a year old. Fortunatley this was caught on ground prior to takeoff.

Regarding looks, you would have the same external servo/linkage in place anyway. So it seams if operated conventionally there would only be one addition gap to see. If operated otherwise you're probably not flying a "scale" maneuver anyway.

Ragz

On a slightly different note: Do you really need dual servos on a 35% wing if the servo used is a JR8611 @6v class servo? I am currently building a CA 34% and am torn between using 1 8611 or 2 per wing. Price difference between 8411 and 8611 is almost nothing. However, does a plane of this size really need more than 260oz of torque on a single aileron? My ailerons are quite stiff as well..so flexing should not be to much.

Volfy

My Feedback: (23)

In one of the aileron servos goes haywire - you are ****ed any way you set it up.[] Split ailerons actually have an advantage in that at least the adjacent servo will drive the remaining surface normally and possibly give you enough control to limp down to terra firma. On a 2 servo on 1 surface scenario, one locked up servo will fight the remaining good servo and may end up stripping its gears.

Albatross

My Feedback: (7)

I have exactly the same question; short of loosing the flaps that you are envision, splitting ailerons sounds an alternative against servo matching issues. However do we really need get involved in that complication, by scarifying the scale looking?

260oz @ 6 volts for a 35% I think should be acceptable. No sure about certain conditions that will eventually be detrimental such as flutter. However all the 3D maneuvers are performed a very low speed, therefore the pressure exerted against the control surface is in theory less than the one needed for a very high air speed control surface such as the one experimented by a Jet airplane. By the other hand we don't really look for high speed in our giant airplanes.

My old XP783 can be programmed to provide a flapperons function; therefore you still have the flaps functionionality that you are looking for by using a single servo per aileron, I programmed this function long time ago on a my Carl Goldberg Sukhoi, and to be honest I almost never use it.

Volfy

My Feedback: (23)

Torque rating is only one consideration. Servo geartrain load is also another. One standard size servo may have enough torque, but splitting the geartrain load over two servos will mean less likelihood of stripped gears.

This brings up my question: why stick with the "standard" servo form factor? The de facto "standard" servo form factor dates back decades ago when few airplanes exceed .60 in size. Why is everybody still sticking with the same size servos on 35% scale aerobats? I would think a single Giant Scale digital servo with 300 Oz.in. of torque and super-sized geartrain will be the best bet.

Actually, I know why everybody still stick with "standard" size servos. It's because it is the ONLY form factor that all the manufacturers stay pretty close to.

OnTheEdge

I was just talking about this the other day with a friend. The new Hitec 5955 standard size servo puts out 333oz @ 6V. The LARGER 5745 only puts out 250oz. If they can pack that kind performance into the standard size case, then just think what they could do with the larger 1/4 scale size case (not quite the appropriate description any longer ay ) Heck 700, 1000+ oz or more with more robust gears. One of these on the rudder and you you've got the performance and simplicity. The Seiko is kinda there but may not have the precise centering that the digital servos provide.

...........Mark

Volfy

My Feedback: (23)

I think if we can get Futaba, JR, Hitec and everybody else to agree on a form factor for a Giant Scale servo, more ARF manufacturers will be inclined to build their big birds to accomodate servos larger than the "tiny" standard servo.

Diablo-RCU

My Feedback: (1)

I've got an Aeroworks 33% Edge with one servo per aileron, 600+ flights on it. Originally it had JR 4721 nylon geared servos, never stripped a gear. Swapped in Hitec 5945 metal geared servos, no issues. The smaller H9 Cap (97 inch wing), used 2 Hitec 5945 servos per aileron. H9 used more aileron servos to prevent a flutter problem they had with their first generation Extra. The 5945 servos from the Cap found their way into my 35% Wildhare Extra. Eventually two of the aileron servos broke their gears (after about 500 flights total). From a servo power issue, two servos/aileron are not necessary. But, two servos will give a faster roll rate and generally better performance. I think the servo gears fail from the engine vibration hammering them, and it doesn't matter how many servos you have per aileron, eventually the metal servo gears will fail.