Does anyone here recommend pull-pull cable controls for a hand-launch balsa glider? My main goal would be to save weight, but I know there are concerns with the fuse and control components being able to stand up to the tension required to eliminate slop/flutter.

If so, what materials and attachment methods would you use?

The plane is a DJAerotech Chrysallis, standard tail (non-Vee). Comes with 1/8" birch pushrods. Tail boom is 1/16" balsa sheet with 3/32" stringers at the corners.

Thanks,
Tim

I use .012" dia. control line wire for most of my pull-pulls, from small electrics to large power planes.
Don't over-tension, they just need to be taut.

Funny, just asked about the same question here:[link=http://www.rcuniverse.com/forum/Pull%2DPull/m_1579474/tm.htm]Pull Pull[/link]

I'll be interested to see answers...

I used 80# spectra fishing line in my sailaires pull/pull. Virtually no weight.

I set up all my gliders with pull pull systems and I use the same systems the TOC pilots use just in a smaller scale.

As wires I use kevlar wires purchased at intothewind.com.

Saludos

Landi

AMA soaring columnist Mike Garton addressed this concern for DLG's about a year ago with an XP3 and other side arm launchers. His main concern was for rudder push rods or pull pull cables breaking after the high stress of DLG launches.

Your Chrysalis isn't a DLG, so I'm sure you can use pull pull with much more security. I have a Fred Mallet Epsilon with all spectra pull pull controls (rudder, elev) and it works great. Just be sure the tension is enough, but not too much for the hinges you use.

One good trick I learned from Fred was to wrap the pull pull lines under the servo screw after threading through the servo control arm. The screw locks the cable in place, but you can still loosten for adjustments. 50 lb spectra kite string is a good thread to use. It's slippery and strong.

Good point on the tension. I used the technique taught and then a little more ( not guitar string tight)

wind junkie - I assume you're talking about wrapping the line around the screw under the screw head. Does this ever tend to change the tension on the line when the screw is tightened?

I generally like the idea of using the servo screw to adjust and hold in place. Does this allow you to just loop the line through the clevis at the control surface, eliminating the clevis and even more weight?

I mean (on the last post)
Does this allow you to just loop the line through the CONTROL HORN at the control surface, eliminating the clevis and even more weight?

The true weight conscious addict uses a wire for the continuous loop from the servo, thru the horn on one side, then thru the horn on the other and back to the servo... and then hooks up a small extension from one end of the wire to the antenna pad on the receiver PC board.

Neat idea. But will the length knock the recivers tuning out of wack?

Hi

The reason why I like to use Kevlar wires is because u wont ever have interfearence on your reciver. Kevlar wont strech and is just as strong.

Saludos

Landi

Here is a pull-pull system that Brian D Felice posted on rec.models.rc.air several years ago. Many of the power guys have gone to this. It makes setup a snap. It presents possibilities not normally thought about.

http://members.cox.net/bdfelice/

The tuning... dunno.. The typical run of cable out to the rudder and back is pretty long.
I've flown slopers with truncated receiver antennas (cut off by some miscreant trying to knock my plane out of the air while I was intending the same to his... ). and not noticed any range problems with about 1/2 the antenna left.
On my Skeeter HLG, the total length from receiver to rudder and back is over 40".. the usual antenna is shorter than that.
Once a plane gets more than 20° above the ground plane, range essentially goes past the visual limit.