Can I use flexible pushrod for the elevator?
 

Hello,

I am building a Thunder Tiger Stick .40. I could not get the wooden pushrod assembly to exit the rear for the elevator of the plane and move back and forth in a smooth manner. It constantly stuck. I tried bending the pushrod so much that it is unusable and needless to say all of that bending never got me anywhere anyways.

I ordered a flexible pushrod assembly that will be able to glide past all the kinks and give me a smooth operation. My question is, is it it okay to use a flexible pushrod for the elevator? Will this cause any control problems? I ordered the accu-glide assembly made by Great Planes as well as a flexible pushrod assembly also by Great Planes. What should I do?

Thanks,

KB

RE: Can I use flexible pushrod for the elevator?
 

No problem. Just be sure to anchor the outer tube at both ends and at least one plece in between (Every 6" or so is better).

Also, be sure not to have more than an inch or so of the inner tube protrude from the outer without metal reinforcement

RE: Can I use flexible pushrod for the elevator?
 

I am sure Minnflyer's idea will work. I personally don't like the plastic push rods. I don't like the fact that they will get longer or shorter depending on the temp. This will change the trim and is a pain in my book. Sullivan makes both types. I like the ones that are a plastic outside guide tube with the solid metal inner rod. They require a straighter run than the others but are worth the extra time. In most planes they can be crossed in the rear of the fuse for a nearly straight shot.


David

RE: Can I use flexible pushrod for the elevator?
 

I like flexible push rods...alot. I only glue the outer tube at one end so it can expand and contract inside the plane without binding. If you glue it at both ends the outer tube will develop curves because it will not move through the structure.

You'll always have to dial in trims a little here and there.

RE: Can I use flexible pushrod for the elevator?
 

I don't like these for elevators, they change trim too much with temperature. You will have to change many clicks of trim from first flight in the morning to mid afternoon heat. Sullivan does make some splined carbon filled rods that will help. Either way, this type of rod must be well supported or they will flex under flight loads. I have seen more than 1 plane with this setup on elevator not be able to pull out of a dive because the pushrod deflected under load. I suggest you spend the extra time and put in a rigid rod like the Sullivan with the solid metal pushrod inside a nylon tube.

RE: Can I use flexible pushrod for the elevator?
 

If you don't secure both ends the outer tube can bow during heavy pushing loads. This could be a bad thing.

RE: Can I use flexible pushrod for the elevator?
 

i agree with piper chuck on the fact that the outer tube can bow if you only secure one side. i will secure both sides particularly if i am using to span the length of the fuse but if it's really inconvenient and for shorter distances such as the throttle linkage. i find that they work wonderfully!

RE: Can I use flexible pushrod for the elevator?
 

Hi everyone
i have used these gt accuglide semi-flex om my busa 1/6 scale pup first i saved a lot of weight i got the model light tha say instructin manual but i'm afraid that in summer period these will have problem about thermal expansion!!is there someone had problem about thermal expansion?

RE: Can I use flexible pushrod for the elevator?
 

All my forty size planes use Sullivan Golden rods. I do not have a problem with trim. The Sig Somethin Extra that originally used clear poly tubes had a problem with temperature expansion but not the Sullivans. That being said I'm just a sports flyer, I don't fly pattern or 3D.
John

RE: Can I use flexible pushrod for the elevator?
 

I used these flexible rods. They were fine for a couple of weeks, then one evening it was cold and the rod shrunk so much I didn't have enough radio trim to fix the problem. I have removed all nylon rods from all my planes.

That being said, some people like them, and it is not a bad idea for you to try them and find out for yourself. As mentioned above, the more places you anchor the outer tube, the less flex you will have inside the plane resulting in greater precision.

RE: Can I use flexible pushrod for the elevator?
 

There are several of these types of pushrods available, depending on the size of the model. Also you can buy the flexible Sullivan composite Flex Rods, and they do not shrink or expand. Although I have used all of them, the only ones that I had problems with were the white GP pushrods that came with my old prop F-4 Phantom kit. I simply replaced them with the Composite Flex Rods and everything was fine.

http://www3.towerhobbies.com/cgi-bin...?&I=LXFV43&P=7

RE: Can I use flexible pushrod for the elevator?
 

I had sullivan flex rods for my throttle linkage on two of my planes. I was dissatisfied with the performance, but maybe it's 'cause it gets pretty cold in Vermont.

RE: Can I use flexible pushrod for the elevator?
 

Hi when you say composite you refer to the carbon fiberglass?

RE: Can I use flexible pushrod for the elevator?
 

what did you use flex or semiflex?

RE: Can I use flexible pushrod for the elevator?
 

Hmmm...

I have the flex rods on various planes, and I've never had to re-adjust the initial trims, not that it couldn't happen.

I wonder if there is more to it than just the rods affecting the trims where changes are reported.

RE: Can I use flexible pushrod for the elevator?
 

what you think about 4-40 sullivan gold'n rod high stress strong not composite

RE: Can I use flexible pushrod for the elevator?
 

1)there are differant flexsto all rods sold , look at the colors when your in the store , you will see some will bend easily other offer more regidity .
2)you can get creative to make sure your model is more secure -as min flyer suggest red outer , yellow inner , you can even cut a small piece of carbon fiber rod to add major regidity at the exist point and over the red portion , this will even make it stiffer .

3)finally you can add some non offensice descrete triangle stock to the "red outer tube" attached to the fuse to add more support .