My control linkage broke. I had a brass connector soldered to the end of the control linkage wire at the elevator. The stainless steel clevis screws onto the brass connector. The brass connector broke in half. I won't buy any more of these brass connectors at the hobby shop. The airplane was almost half way around the loop when I felt the control line snap then I had no control. The airplane flew inverted for a few seconds then it did a wing over and a very large radius loop. It hit the asphalt full speed ahead at about 15 deg angle. The worst part of the damage is the muffle attachment is broken off of the muffler. I might be able to weld it back together with low temp felspa welding rod. I think felspa is a brand name its some type of all purpose brass stuff that claims to stick to aluminum, zinc, brass, copper, cast iron, steel, just about anything. No major damage to the airplane just a smashed landing gear, broken prop, and the tail assemble is broken off. It looks to me like an easy fix.
An easy fix, I agree.
Try some JB Weld for your metal repair. I once fixed a freeze plug in a back area of the engine block on my Austin Healey 3000 with it. It's amazing stuff. I have repaired my irrigation well pressure tank with it as well.
Check it out.
[photo not recovered: 3e69bb3870f12ad5.jpg]
"Never apologize for showing feeling. When you do so, you apologize for the truth." -Benjamin Disraeli
Well, you just learned one of several important lessons about control systems.
Remember, If it can fail it probably will and clevises have killed a lot of stunt planes.
I usually reccomend that builders stay away from them.
Gary,
When it comes to control linkages, remember one thing:
Brass = Bad
I've had brass pieces fail on control systems over the years. Not in a long time as I finally learned my lesson. The vibration is a killer.
JB does NOT work in high stress or high heat. Scott Dinger@hyflo
I hate to tell you this but almost all of my stunt engines, all OS 35 & 40 FP's have their boost port blocked and the material of choise is JB Weld.
JB Weld if applied and cured correctly can be drilled without any problems and in some instances tapped!
I have repaired mufflers and lugs for people who by luck of the draw have to fly over asphalt and sometimes crash.
I've mixed JB Weld with CF with pretty good outcomes. Just ground up some CF and mixed in the fibers. Haven't tried to tap it, though.
I learned exactly that lesson back in my RC Chopper days. I had soldered the threaded brass fitting onto a piece of music wire. The brass failed at the point that the threads ended (the threads were cut into the brass, so that spot of the fitting is a stress point.
I am sorry for you loss. How many flights did you have on this airplane before the brass tubing failed?
Mike C
>I am sorry for you loss. How many flights did you have on
>this airplane before the brass connector failed?
>
>Mike C
I had about 100 flights on it when it crashed. I have crashed it several times before, as I recall probably about 5 crashes. One crash destroy the outboard wind and I glued it back together like a gigsaw puzzle. All those crashes may have contributed to the failure of the brass linkage connector. I put my OS Max 25 FSR engine back on the airplane again. I had this engine on the airplane once before. It was a bit fast with a 10x6 prop so this time I put a 10x5 prop on it. I might experement with a 10x4 and 11x4 and 11x5 prop. I repaired the airplane after dinner today here is a pic. WOW, the quality of the picture SUCKS after I change it from 100K to 50k so it can be uploaded.
Gary,
From your picture, and this may be misleading but it looks as if the elevator control rod is being flexed in an arch, is that picture correct?
I had to build my own control horn because I could not buy one long enough to reduce the sensitivity of the elevator. The control horn is 2" long and the linkage rod is attached at 1.5". The airplane use to turn so shape it would do a loop in a 3 ft radius and stall out. The airplane was also tail heavy. I moved the engine all the way forward as far as I could but it still needed more nose weight. I switched to a heaver engine with a plastic prop and heaver wheels and the elevator was still too sensitive. I cut 1" off of the elevator but its still too sensitive. I made a 2" long control horn and experements at the flying field. I could not get the control wire to fit in the correct hole so I put a slight bend in the wire. The bend is not much less than a 1 deg bend. My control wire comes out of the trailing edge of the wind. I have never liked cutting a hole in the wing for the linkage wire. I always drill a hole in the trailing edge of the wing and glue in a piece of brass tubing. I slide the linkage rod through the brass tubing. It works great and look much better than a hole in the wing. The brass tubing makes the linkage wire more stable because if supports it in the middle but it also makes it less moveable up and down when it comes to trying to get the linkage wire into a different hole in the control horn. The linkage wire will go up/down about 1" which is all I need in most cases for the movement of the elevator but on this airplane the linkage wire was in the wrong place after the airplane was finished so I had to bend the wire. I have plenty of clearence between the 3/16" brass tubing and the 3/32" control wire it slides in and out very easy.