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DLG rudder pull pull


Tilman Baumann
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Tilman Baumann

I have some issues with my mini DLG.

I added a rudder. And to save weight I opted for a pull pull system to save weight.

The servos I used are not good, I need more power. And I can only fluty one cell with this servo, but the receiver I use does not like that well.

But my bigger problem is slack in the lines. I don't have space to put the rudder servo on a slider. But how to I put tension on the lines?

Every solution I can imagine is too big.

On the rudder side I have a simile bent wire hook. Hard to adjust that.

Posted Image

Whimpy servo.

Posted Image

Huge slack after one flying session. This can not be the solution.

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Tilman Baumann

Wire and string, could do that.

I also have a 1mm carbon rod. But that's probably too sloppy for a pushrod.

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pete beadle

Hi Tilman

 

The usual way to cure this problem is to produce a "proper" closed-loop system - without brass threaded adjusters at the rear...

With a closed loop system, as used in scale gliders, you have two pieces of "laystrate" multi-strand wire, as used in control line control wires.

You then need four brass or aluminium tubes of 1/8th ID about 1/4" long and two horns, one each side and fixed solidly to the rudder.

The two wires should each be about 6" longer than the length of the distance between the servo output arm and the rudder

 

You feed one end of the wire through first tube then to one side of outer hole(s) of the servo output arm (the servo horn you have is fine) then back through the tube, producing a loop, then back again through the tube - you then crimp thewires into the tube using a pair of crimping pliers or a pair of wire cutters (carefully!)

Crimping should fix the wires solidly in place so they don't slip out 

Attach the wire to the other side of the servo output arm in the furthest hole from the centre as before

Run the left wire through the fuselage and exit the rear of the fuselage through a hole, or slot, cut in the fuselage about 3" ahead of the rudder horn(s) then through the outer hole in the left side horn, back and through again, as per the front ones

 - fix that in place by crimping the wires through the tube so the wire is tight but not too tight

 

Run the right wire through the fuselage exiting in the hole or slot in the right hand side, centre the rudder, fix it in place using a bulldog clip or similar, run the right wire through the outer hole in the right rudder horn through and back then through again, but this time pulling the wire through, from the rear and producing a good tension in the wire, not quite enough to dislodge the bulldog clip holding the rudder centred, crimp the tube trapping the wires, in tension, making sure the wires cannot slip out and slacken the tension. Trim off the spare wire hanging out of the crimped tubes both sides

If your closed loop wires go slack in use, its because they've slipped out of the crimped tubes so just do ONE side again which will adjust both wires at once

Sorry this is complicated to explain but, as soon as you do your first one correctly you'll see both the principle and the practice and see you don't need in-line adjusters to be fitted in the loops

Good luck

Pete

BARCS1702

ps - rudder horns are best made from brass or PC board not plastic.....

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Use guitar string, the finest string you can get with a pull sett up and a spring in the hinge line.  You'll end up adding too much weight putting adjusters on the pull-pull :)  Use very small dia alu tube for the crimp on the wire.

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Tilman Baumann

I drilled and glued the wire. Perhaps also a source of slack.

Adjustable tensioners are to heavy, one string and a rubber band will be my next test.

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Tilman Baumann

Oh, that Tailset Accessory Pack mentioned in there is pretty cool.

All my problems solved for 3 quid.

 

But the real problem is, I kind of need it done for the trip to Lundy end of the week. It's really down to the wire.

Either I can get this working reliably in time or it stays home. (I don't think there is much of a chance for really low wind days anyway. So that is all right.)

 

Even if I get the spring stuff in time. I don't think I can get the servos too.

 

PS: The servo kind of works still. 90% or so. I mus have over stressed it in it's previous life as a aileron servo.

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You can probably get the accessory pack tomorrow. Bowings is pretty quick.

You should be able to get the servos too. I use T9 or phoenix models. Ring and ask :)

 

Can you do it in one evening ??

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Tilman Baumann

I can do it on the island if I have to. :lol:

 

I just ordered 2 x Corona DS-928BB Digital Servo from Giantshark via next day delivery.

Waste of money, but hey, would be a shame if I take that plane with me and can't fly it.

Crazy last minute stuff. I had already decided to leave the plane home. But I hate to do half things like that.

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Not sure why you have a rudder on a Binary900 (I think thats what you've shown in the photo), its quite happy without one, just use reverse differential on the ailerons to compensate (thats what myself and most rudderless DLG pilots use). 

 

If you are going to go with a pull-spring, you want the rudder control horn on the side away from your launch peg.

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Tilman Baumann

I tried without rudder. And even with strong diff I could not get out of the adverse yaw. And it had a tendency to fall out of the sky or lose too much energy before I got it to turn quick.

I liked it much better with ruder.

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Rob Thomson

Lol.    It would fly better with a rudder too - I think a worthy mod.

 

But I like to think I am aloud to make fun of your flying skills - that is until you have survived lundy without loosing a model to the ocean!

 

Hope I dont loose one or I will never live that down  :drool:  :drool:

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