The Perfect Pushrod

[JamieHolford]

Im curious on opinions on a Pushrod for my RSM S1 project.

 I read from some that Ball links are over kill for the S1 but I also see that quite a few praise this setup.

 I would really like to refrain from bending wire for my S1 as I would like an adjustable setup. Bent wire for 1/2a planes is one thing. But on a .19-.35 I know there is better.

 The "pushrod" in hte RSM kit just seems greek to me 3 peices of wire and a carbon fiber tube about 8 or so inches long.

 Someone point me in the right direction. I need yall expertise!

[Bill Little]

Hi Jamie,

Sounds like the RSM pushrod is close to what is used on the "big planes".  One piece of the wire is bent to go into the bellcrank, and gets epoxied (with JB Weld, not the "fast setting") and another piece used at the elevator end.  Three pieces, I don't know! LOL!!

I use a solder on threaded coupler (Dubro part, 4-40 thread) for the elevator end.  Then a ball link screwed on that.  Make sure you will not have to jam the ball link all the way onto the threaded coupler.

Use the CF rod, it's easier in the long run than a wire and a fairlead.  Plus with the threaded end/ball link, neutral adjustment adjustment is a snap.

Big Bear

[Dennis Moritz]

Ball links on carbon fiber tube. No play. Adjustable. Little friction. No friction causing pushrod guide. Use non-waxed dental floss or cloth for hinges. A positively actuated elevator with little drag, definitely a plus in any CL toy plane.

[Bill Little]

Just remember to use the "bolt through" type and not the "snap on" ball links.

Big Bear

[Paul Taylor]

Jamie,
Not sure why you have three pieces of wire. Does the S1 have flaps? If so then one wire will be from the bell crank to the flap horn, the other two wires are of the CF rod.

Do a search on how to do a CF pushrod. I know is may be here or over on SSW. It is not real hard to do. You will need some JB weld, epoxy, some type of strong thread to wrap the ends of the CF rod to help prevent break out, a drill bit the same size as your wire.

If your wire does not have the thread ends, you can get thread rod from CLC along with the ball links.

I will try and post some pictures when I get home tonight or this weekend if you don't find the link.

[JamieHolford]

I guess I was jsut more concerned about the overall look of this setup with the CF tube.

Here is a pic of the stuff in hte hardware bag minus the leadout, bellcrank and weight box.

I have no doubt that the setup is fine when done correctly. In my mind I think it jsut would look right!

[Paul Taylor]

It is hard to tell with my bad eyes, are the rod ends threaded?

[Paul Taylor]

Jamie,
This is what I think it best.

Threaded ends from CLC.
JB weld them in then wrap the end with epoxy. Be sure to wrap tape around the CF rod when you cut it to size. Then remove the tape. Keeps it from breaking while you cut it.

You can use what you have but if the ends are not threaded then you have to bend the wire. No room for error or to adjust.
I know there is something on the web that explains how it is done.

[Bill Little]

HI Jamie,

Don't worry about "looks", the ability to adjust the pushrod length will always come in real valuable.

It looks like the CF tube you have is of the "arrow shaft" size (I have never actually "seen" what Eric supplies in his kits).  Very popular before Tom Morris brought out his "smaller" rod set up.  The dowels are to plug the end of the shaft trapping the wire.  I used to notch the dowels (so that the wire will fit on it flush), drill a hole on the shaft for a tang bent on the end of the wire to go through, then epoxy it all in together.  Wrap the ends back 3/4", or so, when done with wire, thread, etc., then epoxy over it all.   What is supplied will work very very well.  I would, however, use a piece of threaded rod, or one of the Dubro threaded couplers, on the elevator end. 

Of course, just using the parts as supplied will work, just be very careful measuring.  We had to do it for decades! LOL!!

Big Bear

[Rob Killick]

Jamie ,

Take a look at this article . It may give you a better "picture" of what you are looking for .

Others here , with more expertise can chime in , as to give you a better set up , for your control system.

Best of luck,

Rob K.

http://www.fesselflug.eu/html/controlsystem.html

[JamieHolford]

Seems like this is the most difficult part of the whole damn plane lol.

 Thanks for hte advice and help!

[JamieHolford]

Found this over at CLC

 From what I can tell. Just give him the length I need. Add the ball joint and go!

http://clcentral.com/proddetail.asp?prod=PRBL%2D2

THen again I do see its for the Flap horn to Elevator

[Jim Kraft]

I think the smaller short piece of wire may be for a tail skid or tail wheel. To small to be a push rod. One thing about a solid 3/32" music wire push rod with a fair lead, is that they are trouble free once set up. I have used both styles, and still prefer the solid wire. But then, I am kind of old school. I just bend one 90 deg. bend on each end after making a pattern out of coat hanger wire. Then either solder on a washer, or use 3/32" wheel collars. I have never had a failure, and my controls are butter smooth.

[Paul Taylor]

Jamie,
One thing I did once was just slide the CF rod over a full length wire push rod, plug the ends to secure it to the wire and attach the ends. The CF is just there to eliminate flex.

Keep it simple

[Bill Little]

I think the smaller short piece of wire may be for a tail skid or tail wheel. To small to be a push rod. One thing about a solid 3/32" music wire push rod with a fair lead, is that they are trouble free once set up. I have used both styles, and still prefer the solid wire. But then, I am kind of old school. I just bend one 90 deg. bend on each end after making a pattern out of coat hanger wire. Then either solder on a washer, or use 3/32" wheel collars. I have never had a failure, and my controls are butter smooth.

Hi Jim,

Well, I just got real spoiled using the ball link systems from Tom Morris.   Once the parts are made (the JB Weld having to dry kills me! LOL!!) it's just SO EASY to set up the system and it works so free and I never did really figure out an easy way to adjust the old solid wire pushrods once the plane was finished.........

(admission of guilt: I have used solid wires push rods with in the past year.  ssshhhh don't tell anyone!)

Big Bear

[john e. holliday]

Yes we are spoiled with the stuff that is available.  I remember a lot of kits in which the pushrod was already in the wing.  The wing was installed in the fuse.   The stab/elevator was last.  You put a Z bend or L bend in the pushrod close to where it should be.  Install the pushrod end into the control horn and the stab/elevator into the fuse slot for it.  Made sure bellcrank movement was centered.  Then slide the stab/elevator back or forth so the elevator was in neutral position.  Made sure it was square with fuse and glued it.  I remember a lot of plans having either a drawing of the pushrod or the deminsions.  I think the closest I got to having it like the instructions was about an 1/8 of an inch.  Sometimes the stab/elevator were a 1/4 inch forward or back from plan detail.  But, they flew great for me at the time and in the day.   

[Jim Kraft]

On some profiles I have put a 30 degree Z bend about an inch long just behind the wing. By bending it more I can shorten it, or bending it flatter, I can lengthen it. Makes a nice adjustable push rod. The Z bend can be at either end, but will not flex if kept at one end or the other. I think I got this idea from Allen Birckhaus on one of his construction articles.

[john e. holliday]

Remember the "V" bend on all the 1/2A's?   Never used it on the bigger planes.   

[Bob Reeves]

Jamie,
One thing I did once was just slide the CF rod over a full length wire push rod, plug the ends to secure it to the wire and attach the ends. The CF is just there to eliminate flex.

Keep it simple

This is the easiest and in my opinion the best answer to a Ringmaster or Flight streak kind of airplane. You can buy/order long threaded wire push rods and the CF makes them unbendable. Small and look good. I also think Ball joints are overkill, a Sullivan gold clevis is plenty strong, just don't forget to use a jam nut.

[Dennis Moritz]

Ball links have less play. Slop in the control system is counterproductive, although some use it to tune out hunting issues at neutral. Also ball links have a larger bearing surface. Golden rods will, over time, wear out the nylon hole. More slop. Of course that's hundreds of flights. Ball links don't do that. Actually, these days, I've been using doubled nylon horns on profiles, the ball link sandwiched. Did it on my last modded Twister. Doing it on a current Magician. Allen Brickhaus said do it, so I did it. About a half an hour ago I looked over those horns testing this and that, man they sure do twist around. Doubled horns reduce slop due to torquing. I even went to a ball link on the bellcrank inside the Magician wing. Better clearance, no worry about a cold solder joint. The Ball also allows the angle from the crank to the flap horn to change geometrically. Dunno. Am I the only one getting compulsive about what used to seem like trivial issues. I plan a quick build Brodak Streak. Want to see if I can do most of it in a day or two or three. I've spent weeks (doing other things as well of course) deciding whether or not to use the fues that came with the kit. The genuine Midwest quality short fues stick weighs 2.8 ounces. Some mighty old fashioned iron wood. I've got full sheets of 36"x1/2"x3" that way a tad more than 2.4 ounces. Obviously I can re-cut the stock fues and loose over an ounce. IT'S A BRODAK STREAK for crying out loud. Why am I thinking about this. Because the LIGHTER STUFF FLIES BETTER, usually, sometimes...

[Dennis Moritz]

Phil Cartier uses the Z-bend to adjust pushrod length. Phil Cartier uses thin pushrod wire and a tight fitting guide (or 2). Phil clips the leadouts directly to aluminum bellcranks without any bushings at all. His foam planes are painted with Rustoleum. They are covered with the cheapest low heat covering plastic available anywhere in the USA. HE PRACTICES the pattern without taking two laps between figures. There is flex in the controls and drag. Phils' fueses are thin cheap ply laminated to foam, the front end wrapped in fiberglass with no extra ply doublers. Man that profile Spitfire (or was it a P40) flew nice last year at Brodak. His PAMPA expert engine of choice is an LA 40. (I think.) Wait. Wait. Very important. There's this straw hat...

[Mike Griffin]

Jamie I have built many of RSM's kits using the pushrod system that Eric encloses for his kits.  First of all I am assuming that you are building his Ringmaster kits since you referred to S-1 in your initial post.

In the picture you posted you have a piece of 1/4 fiberglass tubing, 2 pieces of 3/32nd music wire, 1 piece of 1/16th music wire, and three dowels.

Here is how you assemble your pushrod from those components.

Take one of the dowels and scribe a groove down the side of it so that one piece of the 3/32nd wire will fit in the groove and be flush with the outside of the dowel.  Put a "Z" bend in the other end of this piece of wire.  The Z bend will go in the hole of the bell crank.  Mix up some 30 minute epoxy and smear it liberally around the grooved dowel with the wire in the groove and then insert it into one end of the fiberglass push rod tube.  Put a 90 degree bend in one end of the other piece of 3/32nd music wire (this will go through the hole in the control horn that you will attach to the bottom side of the elevator).  Then score a second dowel just like the first one and slide it in the other end of the fiberglass tube.  Now you should have one piece of 3/32nd wire coming out of one end of the tube with a Z bend in it and on the opposite end you will have the other piece of 3/32nd wire with the 90 degree bend in it.  I will get to the 1/16th inch piece of music wire in a moment.

Before you do any of this and apply epoxy you need to do some basic measuring on length so you will know how far the front piece of wire should be pushed in the tube and the same for the back piece. Once you have the length right, let the epoxy dry.  One thing you need to do in the back piece of wire where the 90 degree bend goes into the control horn is solder a washer on the wire on one side of the horn and then solder another washer on the other side so that you have the push rod secured in the control horn on the elevator.  Some people use wheel collars or JB Weld instead but the solder is the best bet i think.  I always tape my elevator in neutral when I fit the length of the push rod from front to back.  Just use some rubber bands and a couple of scrap pieces of 1/4 x 1/4 balsa to sandwich the elevator between.

The 1/16th piece is for the tail skid.  On a Ringmaster a lot of people just use a skid of some kind instead of a wheel but it is your choice.  Take the last dowel and cut a groove down the side and across the top of the dowel and flush the wire into the groove and bend it over the top of the dowel into the top groove.  Drill a 1/4" hole in the rear bottom fuselage where you want the tail wheel or skid and epoxy it in place and cut and bend the wire according to whether you are going to use a wheel or skid.

I hope this helps.  Because a Ringmaster is not a large plane by comparison, this type of push rod works great and I have built many push rods just like this and never had one fail.  Like someone said...don't worry about it being pretty....just make sure it is secure.  Bill little was right on the money.

Mike Griffin