katman74

My Feedback: (23)

Okay,
I have been to the futaba help page and still no luck. Can someone simply hooking up 4 aileron servos on my biplane
into a 2.4 7 channel rec. radio is a 9c with 2.4 conversion

speedracerntrixie

My Feedback: (29)

With that setup the only solution I can think of is to use a couple Smart Fly equalizers. The Equalizer will act as a Y connector to connect the upper and lower servos on each side. The Equalizer has adjustments so you can match the centers and end points of the servos seperatly. You could enven adjust you aileron differential through the equalizer too. The single input connector would plug into your RX the same as if you are just using two aileron servos.

acerc

+1 on the equalizer's.

katman74

My Feedback: (23)

Thanks Guys,
Got some coming from Cheif Aircraft,

K-Bob

My Feedback: (1)

Assuming a single servo on each wing half, that can be easily, inexpensively, and reliably solved with a few Y connectors. There's no need for servo synchronizers at all.

j.duncker

My Feedback: (2)

Here is how I did it.

First of all set up your TX to use channels 1 and 6 as aileron. See page 47 Ail-dif in the manual.

Plug simple y leads into 1 and 6 Mark for left and right.

Assemble plane and with trim at neutral MECHANICALLY adjust each wing linkage so the aileron is at neutral.

Check that everything moves the right way. Use servo reverse if they don't. The L and R ailerons should move in the same direction if you have the same set ups top and bottom.

This is cheaper and simpler than going the with the extra electronics of equalisers. It will also be more reliable, remember it is not if a piece of electronic gadgetry will fail it is WHEN.

daveopam

My Feedback: (9)

I would also use two Y's for that set up on a 9C. Channel 1 for the left with a Y and channel 6 for the right with a Y.

David

jetmech05

yep 2 y's

speedracerntrixie

My Feedback: (29)

A pair of Y connectors will of course work but you will never get the throws of all 4 ailerons the same. An Equalizer will allow you to adjust all 4 servos to have the same nuetral and end points. Getting the linkage geomerty the same isn't too difficult but in 15 years of setting up multiple servos on control surfaces I have never seen two servos have the same centers and end points out of the box. The only way I have been able to make a Y work well was with Hitec servos and a programmer.


It all boils down to your expectations for your airplane. It takes me a good 50+ flights to get a new aerobatic airplane dialed in while others push the trims a few clicks, adjust throws and they are done.

Gray Beard

My Feedback: (-1)

I have had and seen too many Y-harnesses fail and cause problems. Gave up using them years ago. For multi servo set up when I run out of room in my radio I have the older JR Match box so I can set them up as Speed mentioned. I too have the 9-C with a 2.4 module and the aircraft set up is no different from 72 to 2.4.

j.duncker

My Feedback: (2)

I have never had a y harness fail or seen one that had failed. What went wrong with yours?

opjose

Heh, putting the "shoe on the other foot" here...

A set of "Y" cables is far simpler and more reliable than the added complexity of a matchbox ( though I really like those devices too ).

Kiss applies.

As far as "the throws of all four ailerons the same".... as long as all of the servo horns are in the same orientation, all of the throws WILL be exactly the same.

At worst a simple reverser on one side wing pair will fix any problems with not being able to mount the horns all on the same side.

speedracerntrixie

My Feedback: (29)

Take any two servos you wish ( except programmed Hitecs ) and hook them up to a Y. Check them for center and end points on high rate. If you post pictures of the two matching perfectly I will eat all the crow you can send over. When I set up my Colombo 38% Extra with JR 8611A sevos the centers were so off that even with Matchboxes I had to group servos together that were the most like their counterparts. The difference between the tow worst servos was around 12 degrees.

DavidAgar

My Feedback: (108)

I agree, you need something that will center the servos and make sure the servo movements are matched. I am a complete Futaba man myself, however my son has one of the new Spectrum 18 channel radios. Setting up his wings was a snap with 4 servos. I have done the same with Futaba, but I do have to say that Spectrum is so much easier. Good Luck, Dave

Gray Beard

My Feedback: (-1)

Different speeds from one servo to servo, sluggish reaction time, servo jumping, servos stop working, servos not working at all, servos not centering correctly, servo throws different. One day just for grins while setting around in a friends shop we pulled every Y off of his rack and ran a test on them, both JR and Futaba. Right out of the pack we found three that only one side worked. Ys may be cheaper but if it's anything better then a trainer I won't use them. I see Y problems all the time at the field. I can afford Ys but I went ahead and bought the match box. With the great servos we have today that can be programed a match box can make sure your servos aren't fighting each other when centering. Something you can't do with a Y. Just a choice thing and I made that choice a long time ago. I also don't use extensions. I solder in the added length of wire I need. Another choice thing. I have had and seen way too many problems with them too.

opjose

As long as I'm using exactly the same servos, I can and do hook pairs up to Y's all the time and the arms are in the same position at center and at the ends.

The servos are receiving the same signals after all.

If they are not being positioned at the same place, send them back, as something is seriously wrong.

Servo testing devices would be of little use if the same signals caused different arm positions.

Even the cheap servos I've used for trainers, maintain the same arm position when run off a Y cable.

Picture proof is easy to do too... how about a Giant Big Stik with Y'd servos resulting in exactly the same arm position for flaps that are linked the same way?

e.g. both sets of arms to the left...

I just set up four club "trainers" this way.

Will that fill the "eat crow" criteria?

Or a picture of two servos hooked to a Y cable with a protractor next to them to demonstrate the same arm position?

Which would you prefer?

opjose

That would make ALL servos highly unreliable devices indeed!

We would not be able to fly our planes at all.

The same signal goes to both servos connected to a Y.

The servos should be reacting exactly the same way... e.g. 1520uS is -ALWAYS- "center" for JR type servos and if I remember correctly 1520uS is always center for Futabas.

Likewise similar timings describe end point positions, 1000uS to 2000uS, both being travel extremes.

While the exact end point position may vary from manufacturer to manufacturer, identical servos should always react identically.

If you have the type of problems you described above, you have problems elsewhere... look to overly long cables, interference, or power issues.

[link=http://www.bpesolutions.com/atechnical/ServoInfo.Center.pdf]Click me![/link]

Servo timing info for different brands: [link=http://www.ronlund.com/rcheli/HELP_SERVO_PULSE.html]Servo Pulse timing[/link]

scale only 4 me

My Feedback: (158)

I think you're missing the point,,

My experience with Hitecs is they come from the factory (factory programming) with centers very far off from each other also. If you just Y them without using a programmer to match centers and end points your going to have mechanical differential to one degree or another. Sure just using 2 Yed for ailerons on a sport plane, no biggie, but couple 2 for Ele or 4 for ailerons on a 33%er and you'll see they need reprogramming to match them up perfectly.

opjose

I guess that applies to the programmable Hitecs.

I've used programmable Hyperions where this is definitely not the case... one reason the heli guys like their servos is that they are assured of identical movement for CCPM swashes.

All of my non-programmable digital and analog servos line up perfectly when on "Y" cables.

speedracerntrixie

My Feedback: (29)

So you are telling me that the Heli guys are not fine tuning the servo throws via ATV or through the mix when running CCPM? Keep in mind that you are talking to an old heli guy.


Back to the crow eating. I do realize that this would take a couple hours effort but I would be satisfied with any two servos connected to a Y with a 4" arm and degree wheel at each servo.

Jose, you and I have been here long enough for you to know that I am all about airplane setup. I enjoy my airplane so much more when I can fly them and worry only about the control inputs and not having to make a bunch of correction inputs in the process. Imagine a well trimmed airplane the will hold a 45 degree upline while doing a roll and returning to that 45 degree line with only aileron input. This requires the ideal CG and the ailerons working as a balanced pair with equal throw, speed and the correct amount of differential. A Y connector will fly the airplane but will never allow the pilot to get the airplane dialed in to that 98%.

Charlie P.

I've had very good luck with Smart-Fly Equalizer II units when mating servos or multiple pairs of servos.


They are also sanity savers when putting multiple servos on a single control surface.

Bax

My Feedback: (11)

When you're talking about a biplane, as in the original post, you have one servo per aileron. As long as all of the ailerons are centered then the stick, trim, and subtrim are all centered, and the ailerons all move in the right directions when you move the stick, you'll be OK. Exact speed and travel are not at all critical, unless you're building the model for precision aerobatic competition. For most sport flying and sport aerobatics, the fact that you have the correct amount of total throw and good centering, you don't need anything more.

For multiple servos per surface, then things like speed, positional accuracy, endpoints, centering, et.al., all apply or the servos will be constantly "fighting" each other, and will eat gears and battery power.

j.duncker

My Feedback: (2)

Will digital servos have greater positional accuracy?

opjose

No not at all. Of course they do this.

However the same type of servos from the same manufacturer will respond to signal inputs in the same way.

That means if I stick four or eight servos on "Y" cables, they'll all center and travel in the same way and to the same degree of rotation.

Differences in linkages, etc... force or require adjustments but that's a different matter.


Ok I'll do a small video to show with a gauge or protractor on each to show actual degrees of movement.


Differential implies that you either have a different mechanical setup for each side or that you are using separate channels.

The second you do this all bets are off.

I'm only talking about identical servos connected to a "Y" cable.... particularly digital ones where sweep arm wear of the graphite is not a big problem.

Either the servos respond the same, or I've been unusually lucky, particularly on the last four planes I set up.

scale only 4 me

My Feedback: (158)

I think you still miss the point,, it's not about returning back to where they start and running back and forth the same,,

With a Y you can't independently adjust each servos sub trim to get the arms at the perfect start angle (where they center),, you might get lucky and they sit where you want them too or close enough, but not always. Unless they are programmable you'll always have to accept where they fall.