I got Lucky

My first flight with the Pathfinder was Saturday. Everything checked out ok and into the air she flew. Engine was running rich as I wanted it to and I started to gently climb and dive. The plane wasn't responding very quickly and would sort of float in the climb instead of point into it.
The engine started screaming as the muffler bolts loosened and pressure was lost in the tank. I just flew it around until she stopped and then did a really nice feathered in landing.
I wiggled the handle and I couldn't see the elevators move. Walked over to the plane and the solder joint (ala the plans) on the pushrod had come apart. I flew that flight with flaps only. I got lucky.
I now have a one piece pushrod.

Are you saying that down flaps caused the model to pitch up, and so you did not have to fly as if the controls were reversed?

Yeah I never liked the two peice pushrods in Brodak kits, I changed the one in my Accentor to a single peice of 3\32 music wire, much more peace of mind.
Dwayne

My elevator is a bit stiff and was sort of firm in neutral position.
As far as I can tell when I pulled up, the flaps went down and lifted the wing so that it climbed...but not sharply..more like floated higher. When I flew the plane yesterday with the one piece pushrod and felt the difference when I pulled up, the nose went up!!!..that is when I thought WOW...I was flying with flaps only!

I had a Chipmunk do the same thing to me. I lost the elevator completely and was able to control it on flaps alone. It would climb when flaps went down, and fly lower when the flaps went up. The stabilizer still acts and does what it is supposed to do.

And, yes, I do agree on not joining a pushrod with bras tubing.

Norm,
Not wanting to be overly negative , but I think a lot of your problem is in the soldering technique, not the brass couple (which I think is a split tube).

Now I agree that this is a very important connection, but even if you don't use such a connection in the future, you may need to make some reliable solder connections. I'd recommend seeing whether you can find some local person to help out.

I've soldered lots of this type of joint and many other in my 45 years of flying. The difference I think is in the brass tubing. Before I used a regular brass tube and crimped it and soldered it. Never had one fail.
This time I used the brass coupler that came with the kit. It's heavier and not so crimpable.I sanded the pushrod ends, used flux and good heat and had a nice running shiny solder. Then it let go. SO...maybe this is a warning to others to watch that particular aspect of the Pathfinder kit.
Neat to hear that this has happened to others...it's always good to hear that you're not totally crazy!

Well it certainly sounds like you did the right thing. Out of curiosity, can you pull the music wire out, and if so, is it wetted by solder ?

I am wondering what exactly let go--the solder to the split tube, or the solder to the music wire, or just the solder itself.

>Are you saying that down flaps caused the model to pitch up,
>and so you did not have to fly as if the controls were
>reversed?
>
>Dan

This same thing happened to me two years ago and I had to fly as if controls were reversed. When I pulled up, plane nosed down.
Why was it different for me?

Well, Rick, we've been meaning to tell you that you are "different" since about age 7. We just didn't have the heart.

Seriously, I'd think that on a perfectly balanced plane, the nose would go down ever so slightly and the plane would gently climb.

Just a guess, was your airplane nose heavy with a fairly small stab?

Not nose heavy and the regular size stab for a Pathfinder.

Hi Norm, I kinda figured your airplane was in trim. The question was aimed at Rick (Catdaddy), I should have adjusted for windage..

Just to add a little info to the thread..

If you really need to join two pieces of music wire use the split couplers from Dubro and make sure you have the ability to create a good solder joint. I have done this numerous times on 35 sized stunters and never had a problem.

I have found that when soldreing pushrods together that if I put a smsll hole in the joiner that it can vent and both ends of the rods will solder..
What happens is that the heat biulds pressure and the solder is blown out of the end that was soldered first..

Try this on a piece that isn't goin' an a model. Then see how it works..
Good Luck, Gil

I took one look at the size of the Pathfinder when I started building it, and went straight to Central Hobies CF pushrods and ball links. I can see the solder links on small models, but there are so many single failure points on our models anyway, I couldn't quite handle that one. (Love my PF, too.)
Kelvin

First a disclaimer: On my Pathfinder I am using a Central Hobbies Titanium ends and Carbon fiber pushrod.

Ok, that being said, I managed to find the split coupler.

#1) It is some type of plated (brass) iron (my magnet attracts it).
#2) I really think it is pretty strong, assuming that the pushrods end up reasonably close to each other.
#3) ....

>First a disclaimer: On my Pathfinder I am using a Central
>Hobbies Titanium ends and Carbon fiber pushrod.
>
>Ok, that being said, I managed to find the split coupler.
>
>#1) It is some type of plated (brass) iron (my magnet
>attracts it).
>#2) I really think it is pretty strong, assuming that the
>pushrods end up reasonably close to each other.
>#3) ....

The ends were within 1/8" of each other. The strength of the split coupler is not at question. In fact the point I was trying to make was that it was too strong to crimp...without big muscles anyways.
I have had great success with lots of planes with simple thin brass tubing. This little piece didn't work...for me.
Just was trying to let ppl know about a potential problem. One piece pushrod is the answer...titanium or carbon or coat hanger.
I got lucky.

LAST EDITED ON Dec-01-03 AT 11:02 PM (CST)
 
It makes sense. With a horizontal stabilizer, when you give down flap, you're giving the wing positive incidence with respect to the tail, so the plane will pitch up. WITHOUT a horizontal stabilizer (e.g. one of the RC Simitar flying wings), put the "flaps" down and it'll pitch down.

My very first flight with my own very first plane ended up with the pushrod coming loose (all sheet .049). All of a sudden, the plane started climbing and diving gently until the fuel ran out. And then I discovered that I was about 40 feet from where I'd started...

(Before that, I tried flying someone else's plane, and ended up figure-9'ing it into the ground..)