It's nice to be Lucky

An RC friend of mine is getting back into CL and built a Sig Banshee (sp) I got to the back yard just as he and another friend launched it. I watched intently and was pretty impressed by how level it was flying. It seemed to be doing really well when he went into a wing over and never pulled out. It went straight in like a lawn dart.
I thought for sure there would be major structural damage but I was wrong. Minor damage to elevator and a broken prop was it. Oh yeah and a load of dirt in the engine. The cause was not hard to figure out.
He is putting it up again tonight weather permitting.

It didn't hurt that the ground was nice and soft.

Aren't you supposed to solder those things in?????

Some days you're the bug, some days you're the windshield. This was a windshield event.

Oops, luckily a cheap lesson.

I went and test flew my Brodak Mustang and was getting ready to take off for a 2nd flight when I noticed the Dave Brown pushrod I was using was jsut about to fall apart. I forgot to glue the ends in. It was a quick fix, but with my luck, it wouldn't have turned out to be such a nice story as in these pictures.

9.6

It's a bit off of 90 degrees, otherwise it would have been a 10. Pretty good though. I'm glad there was only minor damage.
It's not often one can learn a major lesson so cheaply.

Hmmm, pretty cool. My pushrod misfortune ended in a pile of "popcorn" that used to be a Black Tiger. I LOVE flying over grass. Glad everything turned out so well. I have a similar picture of my second r/c plane like that. That thing used to spin in some fashion that I never did learn to recover. I was just glad it missed the very expensive quarter horses that were in that field! Sort of a sick feeling when you have what seems like hours watching a plane wreck.

Let me guess. The other end of the pushrod was also threaded, and there was another clevis there as well.

>Let me guess. The other end of the pushrod was also threaded, and >there was another clevis there as well.

Hmmm?

If this is not the case(pushrod rotating)the jam nut should have held everything OK. In fact, the jam nut should have prevented the pushrod from rotating anyway if it was tight.

Solder is maybe the best solution anyway. Sullivan clevis' are cheap and/or solder can be broken away and the clevis reused.

I don't think re-using a clevis is a good idea. Come to think of it, I don't think using a clevis once is all that great of an idea either. Ball joints are cheap.

>I don't think re-using a clevis is a good idea. Come to think of it, >I don't think using a clevis once is all that great of an idea >either. Ball joints are cheap.

All true. I must confess I am not familiar with ball joints and have been somewhat concerned they look like they could be more failure prone than a good clevis.

I have never had a clevis fail, but have a reliable report of a Great Planes clevis pin breaking in a large, 60 size stunter so am rethinking going to ball joints. One problem I see is a lack of space for the wider ball assembly at the elevator horn, assuming I get the ball joint mechanics figured out to my satisfaction. Basically, you only have slightly more than 1/8" of room inside the fuse at this point on most designs.

Anybody ever used these black plastic clevis' that I saw at the hobby shop the other day(forgot the manufacturer)? They look pretty heavy duty and are also reasonable?

P.S. Yeah, only use a clevis on one end if you use them at all. A soldered washer works well on the other end assuming a good solder job.

"Should" is a big word.

Yeah, two clevises is bad news. I don't know what Stunt fliers do, but for me, a Z-bend works fine at one end.

Yep, love those 1 point landings. When my plane, Tango Red, went it, it was pretty much the same way. Straight in, power on, into soft ground. But you needed a whisk broom to clean up. Never seen so many pieces. The whole thing just shattered.

At least he built it sturdy.

Looks to me like the big problem was he forgot to tighten the jam nuts. The one from the bellcrank is also loose. I have these same clevis' on two of my ships at the elevator with nary a problem. The TwistMaster is now 3 years old and the Omnium has been flying for two years. I did tighten the jam nuts

Maybe so.. but one thing I've read quite a few times (in RC articles) is to NEVER use two clevises on one pushrod. I guess it's a matter of trusting the jam-nuts to never vibrate loose.

Even in their original use as part of an IBM Selectric typewriter (summa you younger guys may not know what those are), one end was soldered and the other threaded if two clevises were used.

I do have to admit that the other end of my control rods are soldered.

Soldered or not it looks like the thread engagement was only 2-3 threads, that's an accident looking for a place to happen. I always make sure that the end of the rod is fully engage in the threads with everything at neutral. If you can't get there, make new rods. Another thing that helps is a drop of CYA after the adjustments are done. It is more readily removable than Loctite, but leaves a deposit in the thread that produces a prevailing torque that helps keep the nut from creeping under vibration.

Another good thread locking goo is finger nail polish(SP). Two daughters so you wouldn't beilieve the oddball colors that are laying around:)

>Soldered or not it looks like the thread engagement was only
>2-3 threads, that's an accident looking for a place to
>happen. >
>Randy Ryan
>AMA 8500
>SAM 36
>I fly 'em all and love it!

Actually the photo was taken after the jam nut was fiddled with. There were more threads engaged than appears. The main problem was not tightening the jam nuts and using a clevis on both ends. Vibration did the rest. Had I got there sooner I might have noticed this before he took off. I recommended the solder fix after the fact.

That's lucky, allright!

I hit the grass with the best profile stunter i ever had, and even if I tried I wouldn't be able to destroy it so thoroughly!

When I had this good for nothing ship it got just like the picture, stuck in the ground.

Guys were askin' me who was buried under that cross...

In Christ,