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Model Forum / Radio Controlled / Air Models / April 2004Do I need a Servo Synchronizer?
I am not flying pattern, just for fun. Building an airframe with split elevators, one servo for each. Are the accuracy of servos and their positioning so far off as to require a synchronizer? I was planning on using two Futaba 9150 low profile servos I have laying around. Thanks, John > I am not flying pattern, just for fun. > Building an airframe with split elevators, one servo for each. [quoted text clipped - 5 lines] > Thanks, > John It may take a bit of fussing about , but you should be able to get them close enough with mechanical adjustment to suit your stated purpose. I have been using this type of rig on a profile Edge just fine for some time. I may go with transmitter mixing soon to make them more like ailevators to do some crazy things :o As long as your servos centers and travel are in spec and your linkage angles are the same on one side as the other, you should be OK. I'm assuming you're planning on Y-ing both servos off of one Rx channel. Cheers, CR > I am not flying pattern, just for fun. > Building an airframe with split elevators, one servo for each. [quoted text clipped - 5 lines] > Thanks, > John Yes, I am, Both off the same channel. I never would have thought about this if the builder's notes didn't make such a fuss about it. I have run the same type of set-up on two or three other planes and on one I did notice, in one case, with same center, and same full throw, the half-throw was NOT the same. The surface angles were off by a few degrees. Flew fine, big fat and slow, sort of like the pilot. I will give it a go without and see. Thanks, John > As long as your servos centers and travel are in spec and your linkage > angles are the same on one side as the other, you should be OK. I'm [quoted text clipped - 13 lines] > > Thanks, > > John >Yes, I am, Both off the same channel. >I never would have thought about this if the builder's notes [quoted text clipped - 4 lines] >The surface angles were off by a few degrees. >Flew fine, big fat and slow, sort of like the pilot. I built my Flybaby with split elevators using dual servos mounted in the rear of the fuselage. The two Hitec servos were connected to a Y adaptor, and naturally I had to contend with opposing left and right throws. It was reverse one of the servos, or connect the linkages on opposite sides of the servo arm. I opted to reverse the wiring in one servo. Works great. Alan Harriman >I will give it a go without and see. > [quoted text clipped - 18 lines] >> > Thanks, >> > John >I am not flying pattern, just for fun. >Building an airframe with split elevators, one servo for each. >Are the accuracy of servos and their positioning so far off as >to require a synchronizer? >I was planning on using two Futaba 9150 low profile >servos I have laying around. Been using dual servos on one channel to drive split elevators for years. Never owned a synchronizer. Cheers, Fred McClellan The House Of Balsa Dust http://home.mindspring.com/~the-plumber You don't "need" one because you can usually get what you want by making mechanical adjustments on most aircraft. After all, the R/C hobby has progressed quite nicely for several decades WITHOUT having to program servos. BUT, here's a couple of points to make: Calibrating servos to work with each other IS a pretty handy thing to be able to do, however, you have to buy yet another gadget. Before you spend that money, consider spending it instead on upgrading to one of the newer "high tech" radios that allow you to calibrate servos from withing the transmitter's programming. I'm thinking specifically of the Multiplex EVO (9 or 12 channel) radios which have a dedicated "Servo Calibration" menu that's easy to understand and use, but I'm sure the other makers have similar features built into some of their transmitter's as well. MJC > I am not flying pattern, just for fun. > Building an airframe with split elevators, one servo for each. [quoted text clipped - 5 lines] > Thanks, > John | BUT, here's a couple of points to make: Calibrating servos to work with | each other IS a pretty handy thing to be able to do, however, you have to [quoted text clipped - 5 lines] | Calibration" menu that's easy to understand and use, but I'm sure the other | makers have similar features built into some of their transmitter's as well. So he has two servos, one for each side of the elevator. He said he's not flying pattern -- presumably, he's just poking holes in the sky. Why would he need to worry so much about the sides of the elevator matching up? I'd expect a small variance to be barely noticable -- after all, the elevator halves are pretty close to the middle of the plane. I'd expect differences in the servos used for flaperons to be much more noticable than anything in the elevator. Yes, he wants to adjust them so they're as close as he can get them, but for sport flying, eyeballing it ought to be more than accurate enough. The only place that I'd think that you'd really need a servo synchronizer would be on a plane where you had two servos driving the exact same control surface (mostly done on giant scale planes.) And even there, you could do without it, but having two servos fighting with each other isn't pretty.  SignatureDoug McLaren, dougmc@frenzy.com Abandon the search for Truth; settle for a good fantasy. Non-matching servo's in elevator halves can make a BIG difference even on sport planes. It's worth going to the trouble to sync them up whichever way you do it because doing even simple loops and other basic manuevers will be visibly affected by elevator halves that don't know each other very well. It may not be a bid deal on a trainer used for training purposes, but wouldn't that be introducing a problem at a time when a new guy is trying not to wet his pants attempting to do nothing more difficult than staying upright? MJC > | BUT, here's a couple of points to make: Calibrating servos to work with > | each other IS a pretty handy thing to be able to do, however, you have to [quoted text clipped - 24 lines] > even there, you could do without it, but having two servos fighting > with each other isn't pretty. | Non-matching servo's in elevator halves can make a BIG difference | even on sport planes. It's worth going to the trouble to sync them | up whichever way you do it Well, I *did* say to sync them up, didn't I? Yes, he wants to adjust them so they're as close as he can get them, but for sport flying, eyeballing it ought to be more than accurate enough. ... yup, thought I did. If the two halves match at zero and at the stick's extremes, they're probably just fine. You certainly don't need some gadget to mount in the plane to match them up for you (though a throw deflection meter might be nice for use on the ground.) Just use identical servos and do it by eye. If you find that you can't make them match up (because they're just plain different) try some other servos. | It may not be a bid deal on a trainer used for training purposes, but | wouldn't that be introducing a problem at a time when a new guy is trying | not to wet his pants attempting to do nothing more difficult than staying | upright? If they appear to be matched to your eye, and your new guy still can't stay upright, then the problem is probably somewhere other than the two elevator servos. Perhaps your eye is defective. :) Now, if you're doing precision pattern flying, and you're good enough that differences too small to see cause problems, then you'll probably also know what you need to do to fix that. Certainly, I'm not that good :) SignatureDoug McLaren, dougmc@frenzy.com Normality Is The Root Of All Evil. OK. Everybody settle down. Not worth getting all worked up over. Thanks for the opinions, you all mostly confirmed my own. I will keep you updated. John AWWW!!! That takes the fun out of it! . > OK. > Everybody settle down. [quoted text clipped - 4 lines] > > John Good luck Yea, "getting all worked up" is THE definition of rec.models.rc.air :-) MJC > AWWW!!! That takes the fun out of it! > . [quoted text clipped - 9 lines] > > Good luck OK, OK, sorry, go nuts. I'll just sit back and watch the fireworks. :-) John > Yea, "getting all worked up" is THE definition of rec.models.rc.air :-) > [quoted text clipped - 13 lines] > > > > Good luck |
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