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Old Nov 05, 2007, 09:37 PM
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Dave K's Avatar
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Need help with pull pull setup

I am building a sheeted Aerodrome R/C 24" Albatros DII. This is my first plan with pull pull controls and I had a question. Is there a way to fish the pull pull lines through the fuselage after it is sheeted or do I have to run the fishing line before I sheet it? Thanks for any help.

Dave
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Old Nov 05, 2007, 09:43 PM
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You can run them after if there is not much in the fuse to get in the way. I use a large needle and drop the line while holding the plane by the tail. Just drops straight through. I also like to install a piece of nylon tube where the line exits the fuse.

Be careful not to cross the lines or to get one rubbing against something in the fuse, such as a cross member.

charlie
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Old Nov 05, 2007, 10:08 PM
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dave,
what are you using for the "cables"?
got any pics of your progress?
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Old Nov 05, 2007, 10:50 PM
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This is as far as I've gotten to date. Plane has been on the back burner for years now. This was my first sheeting job so it's not the cleanest. Not sure what I'm going to use for the cables yet but I'm open to suggestion. Decided to run aluminum tube all the way to the servos for my pull pull cables. It will cost me 6 grams of weight, but I'm so new to pull pull that I am afraid to make a mistake and not be able to string the wires through later. What would you recommend I use for hinges for the control surfaces? I was thinking of using the CA hinges out of my GWS kits, cut in half.

Thanks,
Dave
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Old Nov 05, 2007, 11:34 PM
a.k.a Maltone
Australia, NSW, Goulburn
Joined Jan 2005
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Dave - what I've taken to doing now with pull/pull (I love them!) is mark your plan with exact position of servos, control horns etc then draw in the control lines on side view and top view. This should show exactly where the cables will run within the fuselage, also where they will 'naturally' exit.

Whether to pre-run them is a matter of choice or circumstance. The M1c I built recently, I installed a ply cable guide within the fuselage to slightly alter the line of the cables to meet up with the servos and exit the fuse at scale places. I had a big bundle of coiled cables inside while building.

If installing later, I pierce the exit hole with some sharpened brass tube and insert a length of thin nylon tube into the model and get it up near the servo - then run the control wire down the tube, secure it and remove the tube. Same as is often done with antenna wire.

As I am building a DII much larger than yours - I understand your problems will be much greater than mine fishing around in a tiny fuselage It's looking great!

There is a current thread regarding hinge preferences - I almost always use the commercial 'CA' hinge - mylar with a coating that absorbs thin CA and makes a good bond. (Assuming you actually remeber to use the CA - I didnt and wrecked a Peter Rake prototype when the aileron fell off ). The CA hinge stuff can be bought as 2" X 9" sheets for a few dollars - I have used less than two sheets on all my models to date. I've used strips about 1/8" wide on IPS models up to 1/2" on big planes.

Pat
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Old Nov 06, 2007, 09:02 PM
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Thanks for the help.

I have a few more questions.

1. Can I just use nylon monofilament for my pull pull lines? If not what makes a cheap pull pull line?

2. How should I attach the lines to the control horns on the rudder and elevator?

3. What can I do with receiver antenna?

Sorry for all the questions but I spend most of my time building rubber power free flight planes so I am not up to speed on this R/C stuff.
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Old Nov 06, 2007, 09:50 PM
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1. Never used it myself, but it might be OK on a small model. I use "Spiderwire" brand fishing line. It has no stretch what so ever, and is super strong. The only downside is the color; kind of a mossy green. But you can color it black with a Sharpie.

2. I use a piece of small diameter aluminum tubing (1/16" o.d.), about 1/4" long. Slip the control line through the tubing, then through the control horn, and back through the tube. Squeeze the tube with some pliers to flatten it, and then add a drop of thin CA at the end of the tube away from the control horn.

3. With an airplane that size, I would get one of the micro antennas on the market. They will have plenty of range for an aircraft that size. You won't be flying too far from yourself. Here is some info.

By the way, for hinges on airplanes this small, I usually use cut up floppy disks. Break open the case on an old disk and get the floppy disk out. Cut hinges to what ever size you need. I then lightly scuff them with some medium grit sandpaper, and then use them like regular CA hinges. They are not as stiff so the control surface moves easier, and I have a few planes that are 5 years old now and the hinges are still A-OK.
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Old Nov 06, 2007, 09:50 PM
a.k.a Maltone
Australia, NSW, Goulburn
Joined Jan 2005
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Dave - I used nylon monofilament for my first few models - for control runs, rigging and wheel spokes. Then found to my dismay that it changed quite dramatically with temperature/humidity! Many folk use 'Fireline' or equivelant kevlar fishing line - available in various weights. It is not cheap though unless you talk a fishing enthusiast into giving you a few yards!

For larger models, stranded stainless steel beading wire from craft suppliers is becoming popular but it may be a little heavy for your model. I've used it on 36" size models and up for rigging and controls.

To terminate the control lines (it doesn't matter what sort) I use 1/16" aluminium tube cut into 5 to 10mm lengths. A sleeve is slipped over the cable, the cable fed through the horn and then back through the tube/ferrule. The alignment and tensions can be adjusted and the tube crimped with some suitable pliers. Prior to flying, a drop of thin CA should secure everything.

Some folk like to have adjustable links on the servo ends - I've not used them in the last few models. I just clamp the control surfaces in the neutral position, connect the servos up and electrically and mechanically centre them, then connect up the control lines with no slack. Any final tweeking can be done at the transmitter. (centreing, travel etc.) Try to use holes in the servo horns that are roughly the same as the horns on the surfaces. i.e. same hole-to-hole spacing - otherwise it is possible to get differing tensions in the lines - esp. at extremes of travel.

With the style of model likely to use pull/pull systems (WWI etc) a little bit of slackness in cables at extremes of travel will hardly matter - I'd not recommend my technique on a Pitts special

RX antenna? - I just run it down the fuselage inside and out the back leaving the usual unsightly 'tail' dangling along behind. On a couple of models, I've run it out under a wing. Given the small size of some models there is not much alternative. Wherever it is run, be sure that no strain is put on the wire where it enters the Rx. A small loop and a knot somewhere around a former will stop it being ripped out when you stand on it at take off A few dobs of hot glue can stop it from flopping about inside.

Sorry to rave on here - please bear in mind, this advice is coming from someone who had never flown an RC plane 3 years ago I picked up almost anything I know by asking questions here as you are

It is well worth reading as many construction threads here as you can - every one of them has something to offer!

Cheers

Pat (still learning)
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Old Nov 06, 2007, 09:53 PM
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"Assuming you actually remeber to use the CA - I didnt and wrecked a Peter Rake prototype when the aileron fell off "

I'm glad someone else has done that before

1 and 2. Mono does stretch a bit. I have used kevlar cord (ToughCord, I think) and secured with crimp tubes. I've also used Fireline fishing line and dacron thread, the stuff used for 1/2A control lines. Use a crimp tube (small piece of Al) and then a drop of CA. I sometimes also put a knot in the line up against the crimp tube. You can probably just tie the knot and CA it and be just as secure.

3. Before switching to 2.4GHz I used to run the ant within the fuse to a hole in the tail. On a couple of planes that I would fly in close I would use a small piece of balsa and wrap about half the ant around it, making something like a center loaded ant. The remainder would run out a hole in the tail for a few inches.

If you treat this thing like a "guided free flight" project it will work great.

charlie
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Old Nov 06, 2007, 10:56 PM
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Thanks for all the help. What test Spiderwire should I buy?

Thanks
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Old Nov 06, 2007, 11:04 PM
The Hun in the Sun
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I'm using 30lb test, but I think that's likely a bit of overkill for the 24" Albatros. I'm not sure what other tests it comes in, but I'm thinking 12 would be fine. On the bright side, I can land some pretty big salmon this time of year with 30lb test!
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Old Nov 07, 2007, 06:12 AM
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Cumming, GA
Joined Sep 2004
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I know I'm late to the party but on the small stuff, I've had great luck with Beadalon DandyLine

The stuff I've got is a white 20lb test beading line available from your local Michaels craft store. I've used it for both rigging and control runs. Doesn't seem to stretch, can be colored with a Sharpie or paint and is very flexible. Realtively cheap too! Just looked and found out it also comes in 15lb test that's black.

For crimps, I'm using Beadalon Crimp Tubes. Also available at Michaels.

Hope this helps,
Tom
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Old Nov 07, 2007, 10:00 AM
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I too use the beading tubes and the wire, both of which I also use for biplane bracing.
Here's my solution for the servo end of a pull-pull setup. Very low cost, infinite adjustment.
http://www.rcgroups.com/forums/showp...0&postcount=11

mick
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Old Nov 07, 2007, 03:48 PM
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I hate to throw a dampner on this, but the Albatros rudder horn is INSIDE THE FUSELAGE. Yes, inside that nice fully sheeted fuselage. Sort of complicates the linkage a bit on a model this advanced.
Beading wire works fine on these little models. Look up Greg Whitcombe's threads on Brisfit, Caproni-Pensuti triplane Sopwith Camel and Farman Sport. However, I've never had problems using monofilament fishing line.

Charlie,
You didn't, tell me you didn't forget to glue the hinges on Slingshot. I know someone else who did that, on a much bigger and more powerful model - TWICE!!!

Pete
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Old Nov 07, 2007, 03:51 PM
a.k.a Maltone
Australia, NSW, Goulburn
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"I know someone else who did that, on a much bigger and more powerful model - TWICE!!!"

Um...me too

Pat
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