Wulf

My Feedback: (5)

I`m building aSig 4-Star 1.20 size plane and would like to know if the standard servo setup is good enough to use ,or maybe add a pull-pull system.I have never used a pull -pull system.Can anyone tell what is the best way to install or, for that matter what is it exactly?I`ve also heard of people using dual servos mounted at rear of plane.I`m using a standard Saito 1.20 engine.Maybe I`ll need more weight at rear.I`m ready to install the radio stuff right now and thought I`d ask before I start.I`m also building at same time a Kangke Cap 232 and may want to add pull-pull system to that plane also.I`m using a OS1.08 in that plane.Probably most diffinately need more rear weight in that plane.
Any info would be very much appreciated-

Wulf

Scott McCrory

Wulf

The standard servo setup works very well in the 4*120. I just finished mine a few weeks ago installing the servos as shown and there is no problems. A pull-pull setup uses steel or kevlar cables going to both sides of the control surface. The cable attatches to both sides of the servo arm.It's a little more complicated to set up but very reliable and slop free. There are two other 4*120's in our local club using the stock setup and no one has had any trouble. I have an OS 108 in mine and had to move the battery as far forward as possible under the fuel tank to balance. Hope this info helps. Enjoy your plane, it's a real gem to fly with no bad habits.

Scott

Ryan Nau

My Feedback: (54)

Standard Servos will work. On my Four Star 120 I have a G23 in it, 16x8 prop. I did have standard servos in the elevators, but after about 50 flights I was getting flutter so I put high torqs in and it solved the problem. I used two elevator servos, one for each half. I have standard in the ailerons with no problems and a big high torq on pull pull for the rudder. Does an awesome knife edge. Its a great plane, you should like it, i love flying mine.

markfsanderson

Ryan,
Tell me a bit about your G23 installation, as I am looking to do a G26 installation on the 4 * 120. Did you have to move the servos around at all to get a good CG? This will be my first Gasoline engine aircraft . . . what changes have you done, or wish you had done?


Thanks for your help!

Mark F. Sanderson

Rambo-RCU

My Feedback: (1)

I use only standard servo's in mine. I power mine with Ryobi engines and use a GWS metal gear servo on the rudder just because it don't strip the gears if the rudder gets accidently turned quickly.You can view my planes at http://jagengines.com Then go to customer testimonials . BTW you will probably have to relocate your firewall backwards,With the Ryobi it takes 2" backset.

crashland 73

My Feedback: (24)

any of you guys still have our plans? i would like to build one of these for my g23.

curt2005

Rambo.

I noticed on the JAG site you mentioned you built your 4-stars with split wings. I was thinking of doing that with mine. Any advices, hints, tips, on instructions?


Thanks.
Curt2005.

GPutt33

My Feedback: (2)

Hi Wulf - I built the 4*60 and installed my first pull-pull system in it two years ago and loved it. So this year I built the 120 over the winter and installed a pull-pull in it. Real simple to do I thought if you do one other mod. I used a 'dual bell crank' for the elevators. If you do this, just install the push rod tubes as instructed, buy a good pull pull package from your LHS and install the rudder servo in the middle slot. The kit includes the wire/kevlar (depending on how you want to go), all the hardware to attach to your servo and control horns. Here is a really really helpful site that explains how to set up the control horns on a pull - pull system to take advantage of what's called 'Ackerman'. Basically you set the control horns up about 1/16th of an inch behind the hinge line. Use the installed tubes to the rear for your cables.

Here is the link to the Ackerman document. [link=http://members.cox.net/bdfelice/Ackerman/ackerman.htm]Ackerman Document[/link]

The reason I went this way was I went with one heavy duty JR servo for the elevators hooked up to a Dual Elevator Bell Crank. This let me do two things. One Servo up front (THESE PLANES SEEM TO BUILD TAIL HEAVY, I SUGGEST KEEPING SERVOS OUT OF THE TAIL) and I did not have to use the wire to connect the two elevator halves. I don't like the twist you can get in the two halves under a load during flight by having all of the push and pull on one half of the elevators. By coming back with one connecting rod from elevator servo to the middle of the dual bell crank. and then two short independent connecting rods to a control horn on each elevator, it seems to keep the control surfaces tighter. I get the dual bell crank through [link=http://www.centralhobbies.com/control_linkage/index.htm]Central Hobbies[/link] in Billings Montana.

And if you want a glimpse at all of the above I have a little RC website [link=http://groups.msn.com/PuttsRCHomePage/_whatsnew.msnw]Putts RC Home Page[/link], click on the Pictures link and then look for an album called 4 star 120 build. The picture on my homepage is how my 120 turned out

I've got Saito 150 in it spinning a Graupner 3 blade 15 x 8. Flies like a dream and looks real good in the air.

Happy Building - Your going to love this plane.............