bpryor

My Feedback: (45)

I used to have one of those thingies, but I can't remember if it would spit out what type of servo it was testing. There are certain things that the programmer will do for any servo, and then an expanded set of functions for Hitec digitals, so this could potentially have some very interesting results.


...and so what was the subject of this thread? I think I've forgotten. I promise I'll post a picture of something Yakish tonight to get back on track.

bpryor

My Feedback: (45)

Ok, back on track. Someone asked earlier about a picture of the pull-pull setup. Here are pictures of the front and back....but I'm not convinced this is the right setup. I used the 3" SWB offset arm, which as reported earler is actually 2 5/8", with the rudder setup at exactly 3", and my cables have slack when they get near their limits. I still have my 4" non-offset arm, so I might just mess around with that to see the results with it setup at 3" and no offset at the servo. And yes, the pickup point at the rudder is exactly over the hinge line.

The other picture is of the elevator servo setup. The servo arm is 1.5" and the control arm from hinge line to pivot is exactly 1.5". I didn't measure the throw yet, but it is definitely full 3D throw.

mglavin

My Feedback: (31)

Bill

What's the offset on the SWB arm from center to center? Looks like maybe 1/16" or so.

Also what’s the length from the servo arm output shaft and rudder hinge point?

Another, your wires are crossed? Mount one ball link on the top of the servo arm and the latter on the bottom of the servo arm. Allows wire separation at the intersection.

Servo looks like a knock-off of a Hitec 645MG physically, definitely not produced by Hitec. On the other hand it it has that Futaba label look and uses a Futaba arm, who knows.

bpryor

My Feedback: (45)

Hi Michael,

Thanks for the input.

>>What's the offset on the SWB arm from center to center? Looks like maybe 1/16" or so.

The offset is 1/8".

>>Also what’s the length from the servo arm output shaft and rudder hinge point?

37" even, if I understand what you're asking.

>>Another, your wires are crossed?

Yes, the wires are crossed.

>>Mount one ball link on the top of the servo arm and the latter on the bottom of the servo arm. Allows wire separation at the intersection.

I haven't done that before. I've just always made sure and use vinyl coated wire, but I like the idea a lot.

On the servos, did you read where I mentioned that they make the same screeching noise as Hitec digitals? Can they be analog and be making that noise? If looking at the innards of the servo, how can you identify if it is a digital servo?

mglavin

My Feedback: (31)

You need a 3" servo arm with .25" offset for your 3" rudder control arm with cable pivots over the hinge center line for the best setup at 37" spacing. This nets a cable length of 36.98" pulling and 36.97" on the second cable at 45 degrees defelction. This is good because it goes a little slack on both sides.

With your 2.625" arm the pulling cable gets shorter 36.84" (slack) and the one other cable stretches to 37.09" (tension).

Digital servo amps have at least one BIG chip its the micro processor for the smarts and several smaller units typically. Analog amps don't have much going, no big chips anyway.

Servos are servos for the most part. Premium Analogs and Digitals are comprised of the same basic components less the amp type i.e., Digital or Analog.

The difference of Hitecs 5600 sport series Digitals and 5900 premium Digitals series is the 3-pole cored motor verses the coreless motor. Same basic Digital amp tweaked for each motors values, same Alumalite gear alloy, same M/P output gear, same potentiometer and same bearings. In short the 5600 sport digi's have a different case, gear-set and motor.

I've never heard an Analog squeal like a Digital.

bpryor

My Feedback: (45)

Hi Michael,

That describes the behavior of my setup perfectly. I guess I'll be making my own servo arm, unless Nelson or someone makes one with those specs. Anyone have an EF YAK that wants a servo arm for a Hitec. [] I wonder what the difference in spec is with the "real" EF Yak and the KMP.

Great info, thanks. This really appears to be very close to a 56XX, whatever the origin. I'm almost certain it's a digital though with the noise they're making.

Thanks again for the help.

DENNIS C

My Feedback: (99)

Bill what is wrong with the swb arm that they sell for the EF yak

bpryor

My Feedback: (45)

Well, from what Michael just wrote, it's too narrow(it should be a true 3" if you have 3" pickups at the rudder) and the offset is too small at 1/8". It should be 1/4". This is all assuming you have your servo mounted where I have mine, which I'm sure most people do.

DENNIS C

My Feedback: (99)

Hummm. So are the people that have the E.F. yak having problems with slack in the cables.

bpryor

My Feedback: (45)

Apparently not, from what Wayne posted. My only guess is that there's something different in the setup between the two. Although I didn't know about the offset, I was surprised to hear that the SWB arm was less than 3". I didn't see how that was going to work. There must be something either in the servo location, or in the length or shape of the rudder horns on the EF Yak that makes that setup work.

DENNIS C

My Feedback: (99)

Bill you might want to try and go this route. this has worked for me in the past on my 540.

Use a 2' or 2 1/2 " straight arm on the servo then use a 3 " bellcrank. like i said i used this on my 540 and had no problems at all with slack in the cables infact its a better set up. your not putting any force on the upper bearing of the servo.

bpryor

My Feedback: (45)

Thanks for the suggestion Dennis. I've used bellcranks several times before, but i was trying to avoid the hassle of setting this up on this plane. It's pretty easy to make a arm with the correct length and offset that fastens onto a stock round servo horn if that's what it comes to.


*** I just did a quick check and I think a non-crossed, straight run will work with the stock fuse slots(though I wish I could remember why I didn't think this was the right setup when I tried it before), or close to them....which means I'm going to try a non-offset 3" servo arm(which I have from my first attempt at this) and see how that works. I'll report back on that later today, or tonight.

Man, I hope all my mistakes here at least helps some other people out so they don't have to go through this.

mglavin

My Feedback: (31)

3" straight up at both ends is ideal without crossing cables, as long as your on the hinge center line with the cable pivots... The only variable is where the cables exit the fuse, this may or may not be a problem with the smaller models like this one.

bpryor

My Feedback: (45)

Pull-pull mystery solved. I put the straight 3" SWB horn on, ran the wires straight instead of crossed, and I still had slack....but it was more pronounced, and only when turning in one direction. It took me quite awhile to figure out what was going on. I re-measured everything, and it all checked out. I finally noticed that the gap between the centerline of the rudder pickup point and the vertical stab were different on both sides, even though I had carefully measured the distance from the hinge point to the pivot point and they were exactly the same. Well, it turns out the hinge line was not put exactly in the center of the vertical stab, so there's one more thing for you guys to check to make sure yours is straight...before hinging.

I was easily able to make the geometry come out correct by moving the pickup point of the short side out to correct for the offset. The pull-pull lines are now tight through their full travel.

Now, back to the straight control arm and uncrossed wires. That would work fine, but you'd have to move the exit point of the wires on the fuse at least 6" forward for it to work correctly, and you'd have to do some reenforcing inside the fuse at that point to be able to cut exit slots in...so...I decided to put the offset arm back on and see how that acted with the correction and it too is maintaining it's tightness throughout its travel, but it does tighten up the pull line slightly as it moves, but not enough for it to cause any issues, so I'm going to stick with the offset arm and crossover wires.

What a mess.

drumbum

My Feedback: (1)

well finally got my covering. so i will start the covering job on mine tomorrow. I have been thinking about that pull-pull and havent bought my arms yet. I have a 5955TG im going to try back there. I shouldnt have any problem with the torque there

snowmaker

My Feedback: (2)

What color scheme are you using?

Will a Brison 3.2 with a 20 X 8 wood Menz prop make this plane a capable 3D 'er.

Any of you guys have smoke on your plane. Hows the weight penalty with it?

Geez, lots of questions there lol.

drumbum

My Feedback: (1)

i am using my own scheme with white, purple and yellow. I will post pictures when i get close.. i have to check my stab alignment first . then i will know how much extra work i have to do..


BTW bill. i am using the dubro Pull-Pull.. i havent bought my horn still. Is the final verdict offset with crossed wire?


I was hoping to be flying mine by now but didnt count on crashing a plane and working on another ETC. now i have my house for sale so that may cut into the time a while. I have my HS 5645s in a TEST plane right now to make sure there are no hidden servo problems to be on the safe side.. the only servo i havent "tested" is the titainium gear 5955 i have brand new in the box. cmae with my monokote shipment..

drumbum

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dont laugh at my drawings but this is roughly what it will look like.. the checkers on the fin and wing are not verbatum but will be simmilar.. the ones on the wing will be alternating between purple and yellow

drumbum

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i more post .. good news on the stab tube it is straight

here is a pic that Bill wanted to see about 30 posts ago. I still have to glass my firewall too

snowmaker

My Feedback: (2)

Hey, that looks nice! Hope you get it in the air before bad weather starts in.
Rob. What engine prop combo you using?

bpryor

My Feedback: (45)

That prop is definitely too small for a 3.2. You should be using a 22X8 or 22X10...depends on the prop brand/type. If you use a Menz S I'd probably go with the 22X8 and if a Menz Ultra, I'd use a 22X10. I prefer the Menz S.

>>Any of you guys have smoke on your plane. Hows the weight penalty with it?

I'm not putting smoke in, at least at the beginning, but typically you're looking at 8 oz or so depending on the type smoke pump, battery and tank you use.

bpryor

My Feedback: (45)

I made a final decision to go with the SWB 3"(actuall 2 5/8) offset arm and crossed wires. You could use a straight 3" arm, but you would need exit points several inches in front of the existing ones, and it would take some work to put support in where they need to be.

Lucky, lucky.

Thanks....and why did I ask to see it? I'm glassing part of my engine box too, especially since you need to cut a very big hole in the firewall for the carb on the MVVS. I'm also going to run an 1/8" X 1" aluminum bar on the back side top of the firewall to help with the strength after removing all the wood for the carb. i'm going to try and tie it into the vertical angle pieces already there.

BTW, I like the look of your design. It will be interesting to see the final product. I'm modifying mine a bit, but nothing major.

..as a little aside here, in case anyone's paying attention (or cares) , I sold my MVVS 58 and I'm putting a MVVS 45 in instead. Why? I decided wing loading was more important than insane power...though it was seductive. With my plane being close to being complete I was able to get a pretty accurate weight picture; it was going to be right about 17.25 lbs with the 58, and it should be hovering around 16 with the 45...maybe a bit less.

drumbum

My Feedback: (1)

well 1 wing is almost done. all i have to do is add the yellow to the other.. I deviated a little from my drawing because i made a wrong cut on my pattern[:@] but after looking at it, i like it.. I will get both done before i decide on the checkers on the tips at an angle.

drumbum

My Feedback: (1)

the cuts on the purple arent jagged like it looks in the picture. if you click the magnifying glass when it opens you can see..
its the pixels that make it look that way

drumbum

My Feedback: (1)

heres where im at now,, i kind of deviated from my drawing some due to im running out of purple and want to have enough for the stabs.. so here is what i have so far