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Double push and push rod?

Old 12-19-2008, 11:42 PM
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niteowl5001
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Default Double push and push rod?

has anyone ever heard of a Double push and push rod? Bought a plane from Nitro planes and the model requiers it.
Old 12-20-2008, 12:00 AM
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ChuckW
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Default RE: Double push and push rod?

I've heard of a pull-pull. Maybe what you're seeing is a bad translation in the instructions?

I suppose double acting solid push rods would work too if set up well.
Old 12-20-2008, 12:05 AM
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OzMo
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Default RE: Double push and push rod?

typo I bet
Rod or string or whatever will remain straight in PULL so even if it uses rods its a pull pull....I think[:-]
Old 12-20-2008, 12:27 AM
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Tom Nied
 
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Default RE: Double push and push rod?

Does it have a split elevator? I've heard of making a push rod with a Y end to activate both halves of an elevator.
Old 12-20-2008, 12:41 AM
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JohnBuckner
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Default RE: Double push and push rod?

No its not a typo. It has been done by some ARF's in the past and present while not to common. I have been flying an older ARF called a Maqic Extra (Modeltech) for perhaps three years now and this did infact come setup with a double hard wire push/pull rod on the rudder, Just the rudder and I have no doubt it may also be used in some of the China Model Products airplanes also.

Its consists of a control horn on each side of the rudder with a hard wire pushrod on each side running in plastic tubes forward to attach on each side of a rudder servo horn. On mine I am using a older strandard sized JR digital and totally forgot which.

I suppose the idea is to have a totally stiff therefore fast rudder linkage with zero blowback but thats just my speculation and I,ve no idea if there is any real advantage or not. There is a disadvantage of course you must take great care in the mechanical setup and adjustment or your servo will sing and use up your battery supply rapidly. Once you do have a good setup it has proved no particular maintenance problem in that way and my linkages have been no problem now for the last three years and a lot of flights.

As far as the airplane "requires it" goes, certainly not there are many options in linkages that are open to you.

John
Old 12-20-2008, 01:10 AM
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Default RE: Double push and push rod?


ORIGINAL: niteowl5001

has anyone ever heard of a Double push and push rod? Bought a plane from Nitro planes and the model requiers it.
Simple question: Which plane?
Old 12-20-2008, 05:33 AM
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Default RE: Double push and push rod?

keep it simple and go with a push pull cable set up...sounds like you have everything you need except the cable
Old 12-20-2008, 11:16 AM
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Rodney
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Default RE: Double push and push rod?

Rigid rods on a pull-pull system is almost a sure fire way to get into trouble. Unless you are absolutely sure that you have zero Ackerman set up, the controls will almost certainly start to try to bind up as soon as you are off center position. Always use flexible pull lines and try to have just a little positive Ackerman set in. This allows the line not being pulled to slack off a bit as the other line pulls the surface off center and puts no undue strain on the servo.
Old 12-20-2008, 11:41 AM
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Tom Nied
 
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Default RE: Double push and push rod?

Rodney, that is absolutely enlightening. Now I understand what is going on in my GP Fling. Since I never installed a pull pull system before, the slackened side looked wrong. Now I know it's fine. Thanks.
Old 12-20-2008, 03:57 PM
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JohnBuckner
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Default RE: Double push and push rod?

As I posted before here is the double rod setup on the Modeltech Magic Extra rudder. It is totally stock and already set up with stock hardware and it has all worked very well for over three years now, The airplane is getting a little rough now but it still works great. If the CMP (Nitroplanes) airplane is set up already it would be silly not to give it a try.

John
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Old 12-20-2008, 04:28 PM
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dignlivn
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Default RE: Double push and push rod?




At one time I had my tail wheel set up with
solid rods, using a pull/pull setup. The servo
never buzzed (at least not on the ground).
As Rodney said, I decided to take off one
rod. This way I felt like it would not bind and
or drain the Rx battery. JMO,

Bob
Old 12-26-2008, 03:53 AM
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niteowl5001
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Default RE: Double push and push rod?

Thanks for all the help guys. I think I will go with the cables.

John Franklin
Old 12-26-2008, 11:20 AM
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ABELL
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Default RE: Double push and push rod?

A Goldberg Hot Stik 40 also came with a push pull hard rod set up. Unlike the Magic Extra, the servo is in the tail with about 2" rods. It also has worked fine for a couple of years with no binding or other problems.
Old 12-26-2008, 12:58 PM
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Default RE: Double push and push rod?

I just assembled a NitroModel Extra for someone and there joke for instructions had something called a push push?? Chinglish translation was just a Y system that you make up from that dowel rod they gave you. It's for the elevators so it's not a pull/pull cable system. If you look at the photo in those fine assembly instructions there is something else they are trying to mention and they really do have holes drilled in the fuse for it. I just can't remember what they tried to call it??? Really funny though!!! What they are trying to tell you is that you can also use A Ball Bearing Dual Coupler. If you go to Central Hobbies they have photos of these, #MKD1231 and MKD1251. Once you see them you will understand what Nitro is trying to tell you. It's just a system that has a control arm that comes out on both sides and operates with just one servo that goes to a central control rod that in on the inside of the plane.
By the way, the one I assembled had the set up in the plane for a pull/pull rudder already installed but the holes for the wire exit is on the top of the fuse or deck towards the rear, the holes are covered over!! I took a small flash light and got it back there so I could see the lilight glowing through the covering, then took a pin and poked the covering away. Just a little trick!
Old 01-09-2009, 08:37 AM
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lostdoormat
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Default RE: Double push and push rod?

these items are hard to find. double push push system can be bought from hobbyking for around 10 dollars. they are listed as ( full direction elevator arms ) they work a treat too.
Old 01-09-2009, 09:29 AM
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Default RE: Double push and push rod?

Here is one I put together for my Venus II (120 size Pattern plane) and it works just fine. It uses Sullivan Carbon Composite rods. The rods go into their respective guide tubes that are epoxied to the formers within the airframe. This is very solid and allows for individual mechanical trim adjustments for each of the elevator halves.

CGr.
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Old 01-09-2009, 09:51 AM
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Default RE: Double push and push rod?

ORIGINAL: ABELL

A Goldberg Hot Stik 40 also came with a push pull hard rod set up. Unlike the Magic Extra, the servo is in the tail with about 2" rods. It also has worked fine for a couple of years with no binding or other problems.
On my Hot Stik they're about 8" (funny how they don't SEEM to be so long). Here's an image from the manual that shows it well. I hooked a HiTec HD-655 servo on and don't notice any problem with the Ackerman effect. I think because I carefully made sure the connection points on the control arms were exactly as far apart as the points on the servo arms.

It's proved to be a rugged set-up and easier to install than a wire pull-pull (IMHO). SUPER rigid and responsive. And you need that on the Hot Stik. She's a handful!




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Old 01-09-2009, 11:17 PM
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ABELL
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Default RE: Double push and push rod?

They are longer than "I" looked. That set up has worked very well for a couple of years. Yes it is a hand full !!!!!! Did you set yours up with flaps or full length alierons? Mine is set up with flaps and you talk about some tight loops. One was so tight you could almost hear the wing crack[&o]. But Ben (my son) got it on the ground in one peice. Repairs were made and she still flies great. It's powered with a TT Pro .46 with an APC 12/5. I was afraid that was not going to be enough motor but, it will hoover at about 1/2 throttle and pull out just fine. I really like those Goldberg planes. I had a 67" Edge 540 that the expiration date come up on. They are no longer available. I sure wish I could find another one of those.
Old 01-09-2009, 11:42 PM
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Charlie P.
 
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Default RE: Double push and push rod?

Yep. I did the four seperate aileron servos but mixed to either act in pairs or independantly (depending on the switches). I had to visit the Futaba site and download all kinds of tips on programming and read the HArry Higley book on the 9C about eight times to figure out what I needed. It is my most complex mixing project to date. I have the CROW/Butterfly feature programmed in and it is a gas to swoop in and suddenly alight like a feather.

Small world! I have a TT Pro-46 on mine, too. I have a Perry carb in place of the original (this engine is on it's fourth airframe and the original needle valve was sheered off in a dirt-bath) and at the moment have an APC 11 X 5 as the prop.

I have to be in the right mood to fly this bird. It is a rush but wears me out! On the maiden I gave it just a touch of up elevator and it was 60 feet in the air in a heartbeat. I have gobs of exponential in the elevator and ailerons, and it will still roll faster than my eyes can follow at full throw.

It is the only model I have ever flown that will loop in one fuselage length.

Maybe they'll bring it back. The covering job alone was worth the price. It was just after G.P. bought Goldberg that it disappeared.
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Old 01-10-2009, 01:47 PM
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Tom Nied
 
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Default RE: Double push and push rod?

That's quite a handsome plane Charlie P. I'd get into trouble real quick with those large control surfaces. Maybe I'd be ok with the throws dialed down.
Old 01-10-2009, 02:11 PM
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ABELL
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Default RE: Double push and push rod?

My radio was holding me back on the crow mixes, and it still may be. I just got a 2.4 7C and I am still in the learning stages on it . I had to visit the Futaba Forums here on RCU and the FAQ pages on the manufactors site just to get the dual elevator mix set up on it. Seems like there was some miss information on which channel to use for the other servo. Futaba was saying channel 7 but it turned out you have to use channel 5. I had been using their 6EAX radio, While a very good radio you were very limited on the mixing. I'm still not sure the 7C will do what I want but for the price it was a very good deal. Now I'm using the 7C on an Extra but have intentions on using it on all my planes. It will cost me $500 to outfit the rest with recievers so it will be a one here and one later conversion kinda thing

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