Working on a Das Little Stick. It will have a 46 or 55 with a pipe on it. Will this push rod system I've set up work OK. I'm worried the rods might be a bit long (7.5") and bend on me. They feel stout enough but I would like some opinions.

Thanks!

They should work. If you are uneasy, go to the #4 rod and clevises, It will ad a bit of weight, but not that much with such short rods.

One bit of advise. You want your servo arms to be at 90 degrees to the pushrod at netural, not 90 degrees to the servo case. The way they are will result in uneven control surface movement on either side of center. Nice looking setup though.

Don

OK, thanks. I just bought an RDS8000 from Tower and haven't gotten it yet. When I figure out where center is, I'll adjust the servo arms accordingly.

Those are right on the edge of being too long. But at least the elevator pushrod is pulling for the "up" direction. If it were pushing, you might not be able to pull out of a dive (keep that in mind in case you ever want to pull out of a dive inverted)

You might consider switching to 4-40 rod - OR - you can lay a 5" piece of dowel next to each rod and wrap it to the pushrod with thread and glue.

If you are concerned about rigidity and weight why not some carbon fiber rods?

Bill

I like to use these
http://www3.towerhobbies.com/cgi-bin...?&I=LXB901&P=7
john

I might be interested in that. Light and rigid - a novel concept. A search on Tower for Carbon Fiber Pushrod came up empty. Where can I procure such a thing?

Thanks!

Look for carbon fiber tubing. I got some from Tower a while back for just this purpose. I had made some pushrods of the 4-40 style a while back and I picked up some square outside round inside CF tubing from the LHS. The ID was just right to use the solder on threaded 2-56 adaptors. I rough sanded to OD of the brass and epoxied it into the tubing. The problem with this was that the brass in 2-56 size is very soft. I nixed that setup. I then found that a 4-40 thread would not quite fit the ID of this. I took a 4-40 tap and threaded the ID about 1/2" deep on both ends. I used a 4-40 short threaded rod, about 1" of full threads, and a dab of epoxy and threade the short rods in each end. I tried the same trick with the round CF I got from Tower, and threaded witha 2-56 tap and it would not take the threading, it split the CF lengthwise before the threads were in far enough. What I ended up doing is used a piece of 2-56 treaded on one end rod. I cut the threaded end off leaving about 3/4" of smooth rod which I kissed with my bench grinder to give the epoxy something to bond to. I then epoxied this into the small tubing. It has made a very good set of pushrods. Very stiff and very light.

Don

Elevator puling Up.

Thanks Mike, I learn something all the time
from you and Ken.

Bob

hiding the elevator controls under looks better but on top is the stronger way to go.

u will be fine with the size of those control surfaces and the rods u R using......

How about maybe slipping a piece of CF tube over the wire, leaving just the ends exposed? Glue it to the wire w/ thin CA...

I generally don't use two clevises on the same pushrod. It looks like you soldered the Gold clevises on and that should work. But if your solder joint breaks loose that rod can rotate out. Soldered clevises can be very strong if done correctly. I just recently built a Bonanza that used a single flex cable running between the ailerons with one servo driving both ailerons. I had to solder the clevises on the cable. It works great. But I was very careful. My first choise would be to use a Z bend at one end of the rod and a clevis and the other end. Its more bullet proof. And since you can easily make that type of installation, I would. Soldering is generally a technique that I use only as a last resort, (except for the throttle). Its just a thought.

One other thing to know. Back in the day, when flat spins were really flat, guys were getting 70 and 80 turns in a single spin. One technique used to make a plane flat spin better was to mount wieght out away from the CG. Mounting servos in the tail, as you have , would be a great way to increase the flat spin potential of a model. Having said that, Stiks don't spin that good, so I would worry. But with that mass mounted in the tail, the plane will have rotational inertia in a spin. You might get some freebies. I don't think its anything to worry about on a Stik. But you might notice something a little weird going on at times. So keep that in mind.

Good points. I had built three of these in days past (back in the 80s) and they always turned out tail heavy with a 46 and a pipe on them. This was my way of trying to counteract that on this one. I've made a few mods to this plane and the mighty mini servos in the tail is one. I also lengthened the wing two inches and cut 3/4" off the nose. All in an effort to keep from having to add lead to the tail. One thing is for sure though, I don't want a tail happy plane!

Thanks!