Noblarf crash

Yesterday at Whittier Narrows a Noblarf (not mine, the engine won't run that long) crashed for the SECOND time. This one looks permanent!

So far as we can tell, it was due to the clevis to the elevator pushrod letting go of the flap horn. The clevis was off, and showed no signs of damage. Had it been torn off in the crash, I would expect some visible sign of tweaking.

The clevis did NOT have the piece of silicone tubing on it that should assist keeping it closed. BE WARNED!

There is also the possibility that the new, larger bellcrank that was installed was not allowed enough room and hung up on some internal structure.

Observers agreed with the pilot that it was not pilot error. The plane diverged from level flight and splattered itself.

I put in several abortive flight attempts on my own Noblarf, Saturday with the Hayes tank, and Sunday with a brand-new metal tank I built Sat. evening. Still no consistent run. After talking to Keith Trosle, we concluded that it might be overheating. SO, back to the bench last night. I drilled the heck out of the tongue muffler, quadrupling the passage area, and opened the front and bottom of the cowl at least double the area in both cases.

We will see next weekend if there is any improvement.

>Yesterday at Whittier Narrows a Noblarf (not mine, the
>engine won't run that long) crashed for the SECOND time.
>This one looks permanent!
>
>So far as we can tell, it was due to the clevis to the
>elevator pushrod letting go of the flap horn. The clevis
>was off, and showed no signs of damage. Had it been torn
>off in the crash, I would expect some visible sign of
>tweaking.

Never, ever, use clevises in a stunt plane. But this is a little different from the leadout situation - at least when the clevis breaks, the crash stays in the circle. That makes a longevity decision instead of a safety issue.

So what do you recommend?

>So what do you recommend?

Ball links, or in keeping with the classic theme, soldered washers.

Brett,
How about some of the "premium" clevises like the Pylon Golden Clevis? They are shorter, stiffer and stronger than ordinary types, and they have a mechanical locking clip. While I realize that they are not as good as trditional methods, they are far superior to the cheaper clevises. There are also some extremely heavy duty nylon clevises with removable pins and mechanical locking clips. I have used both, as well as traditional methods, with no problems, but then I don't fly nearly as much as some people either.

LAST EDITED ON Feb-02-04 AT 05:49 PM (CDT)
 
> How about some of the "premium" clevises like the Pylon
>Golden Clevis?

I have used the Sullivan gold clevis with the clip in the last 3 of my 35 size stunt ships including the TwistMaster and the Noblearf. The Twistmaster is going on 4 years without a problem other than wearing out a brass bushing at the flap horn, easily replaced. I do use a jam nut and lock tite on the threaded rod.

PS: Most 35 size stunt ships do not have room for a ball ling at the elevator and if you want something adjustable the quick link clevis is about the only choice.

Those Golden Clevises sure seem tough. That is what I used on my Nobler ARF. I also use the Loctite / Jam nut method. If they are installed properly, I really don't think they will break.

Has anybody ever convinced anybody of anything in these posts. After informed suggestions are made, it seems they are always met with a "but on mine"

>Has anybody ever convinced anybody of anything in these
>posts. After informed suggestions are made, it seems they
>are always met with a "but on mine"
>
>Al

Al, I'm convinced. You're right, but does that make you wrong then?

I have seen the same things happen with these posts and as a newbie I have to pick and choose what to believe or not. Most times it comes down to common sense for me to make up my mind. Now if you could tell me where I can get some of that I may be better able to make up my mind.

Thanks Al,

LAST EDITED ON Feb-02-04 AT 08:40 PM (CDT)
 
I guess not Al. I'm not convinced that " experts " are always right about everything.

LAST EDITED ON Feb-02-04 AT 09:11 PM (CDT)
 
>Has anybody ever convinced anybody of anything in these
>posts. After informed suggestions are made, it seems they
>are always met with a "but on mine"

I'm often convinced by what I read and hear.
But I'm also sensitive to inconsistencies and they prompt questions.
The questions don't mean I doubt; they ony mean
that I understand that I don't understand and am curious.

In this case, I see Brett say "Don't ever use a clevis. Period."
He used to say "Don't use Kwik-links" which left me wondering
about fancier things like those sold by Ultra Hobbies.

And didn't we see Windy recommending some fancy clevis arrangement
for his bellcranks?

And other people wonder about the little torque caused by
off-center control loads. Seems like the ball links might suffer.

"But then, I worry about lots of things. I worry about reflective flea collars. Sure, cars can see them, but so can the fleas!"
- Lily Tomlin

LAST EDITED ON Feb-02-04 AT 09:43 PM (CDT)
 
I am certainly not an expert, and simply asked a question about an obviously superior clevis. I looked at about every type of clevis in several hobby shops, and did not decide on the Golden Clevises and the heavy duty nylon type without quite a bit of thought. One may fail on the next flight, but I doubt it. I don't doubt that an ordinary clevis is not up to the task, but what I am talking about is a whole new mousetrap. If you don't trust clevises, don't use them. I don't use them all the time, and I have never built anything bigger than .35 size airplane, but I think there is a place for "premium " clevises.

Mostly, I pick up ideas to try on future projects. Sometimes they work well and I like them, and sometimes not. Most of my linkages now are completely different than they were before I discovered this site. Only lost one plane due to linkage failure and it was a plastic 2-56 clevis on a 80-ounce, Saito-.56-powered R/C Arf I converted to C/L. But I have learned plenty here that I have tried. Some things are just too complicated or expensive for me to try. For instance, I now try to occassionally color a canopy, and I will try a little salt next time. But I will probably never ever try to make a canopy from butyrate, pteg or any other plastic sheet.

I have used 2/56 fittings on 1/2 A planes, but use nothing less than 4/40 on everything else.

Never argue religion, politics or clevises.

Amen brother --- I have nothing more to say on the subject, but then again I might!

LAST EDITED ON Feb-02-04 AT 11:03 PM (CDT)
 
The comment that being an expert doesn't automatically make someone right is a good point.

On the other hand, what most experts do have is a lot of experience and exposure to "failure modes" of the equipment we use. When you've done this stuff for 50 years like I have you see and learn a lot of stuff just from having been around it for so long.

I can say the following from personal, hard learned experience. The control systems in our CL stunters probably apply the most extreme loads to their components of any application in the modeling kingdom. Components that aren't up to the repeated loads will eventually, occassionally fail.

I have personally lost top line stunt equipment to: RC Type Clevis failures (yes, bigger is no doubt better and ones with mechanical locks on the pins better yet), control line failure, handle cable failure (no small part of my preference for hard point handles), push rod failures (no magic potions here, just quality workmanship on substantial components) and "slider" type line connectors.

I have personally witnessed other lost airplanes to: handle cable failures, clevis failures, pushrod failures and slider type line connectors.

These aren't apocryphal stories. These were all real, broken balsa, eyeball witness stuff.

I will grimace, cross my fingers and keep my mouth shut at the field on anything up to classic .35 sized airplanes equipped with such components. Once you get into the modern .46 on up equipment I feel compelled to express my concerns to the flyer. I try to make my comments positive and helpful in nature but, having been there myself all too often, I would feel bad about not saying anything.

In fact, I really learned my lesson in Seattle a few years back when I watched a very accomplished modeler, new to the stunt world but a king in his previous event, flying his extremely well finished and trimmed Impact. I helped carry his plane back after a practice flight and noted the Hot Rock handle had a cable that looked like it had seen too many combat tangles; twisted and ugly but no obvious fraying in the visible part of the cable.

Didn't say anything about it and learned probably a month later the cable had failed and the fine airplane was history. Believe me, I felt a lot worse for not having said anything than I would have for piping up at the time and coming off as some sort of know it all.

Truly, guys don't make these comments about clevis' and such because they have something against the mfgrs. History is a good teacher as long as its lessons are heeded.

It's all your fault. I knew it was somebody else's fault.

I consider myself to be duly chastised. If I do ever build a large first class airplane, believe me, I won't use R/C clevises. I will use the best money can buy.

All one can do is relate ones personal experiences, not unusual for different people to have different experiences and opinions with the same product. It is up to the questionee to decide what will work for him.

>> How about some of the "premium" clevises like the Pylon
>>Golden Clevis?
>
>I have used the Sullivan gold clevis with the clip in the
>last 3 of my 35 size stunt ships including the TwistMaster
>and the Noblearf. The Twistmaster is going on 4 years
>without a problem other than wearing out a brass bushing at
>the flap horn, easily replaced. I do use a jam nut and lock
>tite on the threaded rod.

I wouldn't have mentioned it - something about tempting fate! In all seriousness, the standard, HD, or super-HD R/C clevises are just a matter of time.

I have only seen the UHP clevises on one airplane. It's clearly a different case, and I have no information at all on the longevity. The threads on the one I saw were *very* loose on the rod, but that's not necessarily a wear problem if you keep it tight with a jam nut

>PS: Most 35 size stunt ships do not have room for a ball
>ling at the elevator and if you want something adjustable
>the quick link clevis is about the only choice.

Au contraire! A ball link won't fit in the back end of my airplane, either. I use a simple bent 3/32 wire pushrod through a bushed hole, with a keeper. As long as you can turn the whole rod, you can use the adjustment at the flap end ball link to change the flap/elevator neutral.

In fact, I really learned my lesson in Seattle a few years back when I watched a very accomplished modeler, new to the stunt world but a king in his previous event, flying his extremely well finished and trimmed Impact. I helped carry his plane back after a practice flight and noted the Hot Rock handle had a cable that looked like it had seen too many combat tangles; twisted and ugly but no obvious fraying in the visible part of the cable.

Didn't say anything about it and learned probably a month later the cable had failed and the fine airplane was history. Believe me, I felt a lot worse for not having said anything than I would have for piping up at the time and coming off as some sort of know it all.

Ted,

This is interesting. In a call about an unrelated matter I was the one who spread the bad news concerning Rush stuffing his first Impact. And the cause of the crash.

Your comment then was virtually identical to comments made here, quoted above.

Except you asked me to not say a thing about it to Howard, at least not with reference to you. And I never did.

Now you're blabbing this stuff over the internet.

The message: I can in fact keep a confidence, even if that fact does not seem to match my reputation.

You ought to hear what Rush has said about you. In confidence, don't ya know...

Ah well, I got a great Stunt News caption out of Howard's misfortune. And he learned a great deal about cabled handles.

As to the great issue of Kwik-links, assorted snap-on linkage and hardware, I think it is sufficient to note Ted's comments concerning the loads in our control systems. As in they can be very high. Much, much higher than in nearly any RC model.

As these sorts of gee-gaws, gizmos and doo-dads are designed expressly for RC modelers with nary a thought to the needs of CL Stunt people means we must begin at the **very top** of the equipment list, not work from the bottom up.

Looked at another way, ball links deemed too strong, too bulky, too heavy, totally unneccesary for general RC work thus don't sell well and are discontinued by the manufacturer, yet many of us CL guys won't use anything else. Reference: Rocket City #57 and #87 ball link sets, now available from Tom Morris.

So it's ok to keep your mouth shut on a safety issue because some is not in the same food chain as you? BAD Ted .....go to your room, you to DAN.

Scott(ok hit me)Riese

I see some one with a safety issue I will say something. Don't care if your Paul or David. In Fact I asked David NOT to start his plane by himself like he dose. Upside down, one handed, three blade PA-61. Brett held it the next time.

Scott(Been there done that)Riese

Ted wrote:

>I can say the following from personal, hard learned
>experience. The control systems in our CL stunters probably
>apply the most extreme loads to their components of any
>application in the modeling kingdom. Components that aren't
>up to the repeated loads will eventually, occassionally
>fail.

I must say, the only time I've ever flown a real CLPA airplane (it was "just" a Genesis with a OS .40 FP), it about pulled my arm off. These things pull harder than any Fast Combat plane I've ever flown. I can't imagine what a .72 powered monster pulls like. It was the most nerve-wracking experience I've ever had flying a model airplane - for one thing, it belonged to someone else, and was beautifully built and finished, for another, my arm was really starting to get tired towards the end. I did a couple wing-overs, a few lazy 8s and flew out the rest of the tank flying level. I don't ever want to do that again, unless it's a plane I own myself. That's where a Noblarf might come in handy. And I'll be sure to fly it over grass.

So it's ok to keep your mouth shut on a safety issue because some is not in the same food chain as you? BAD Ted .....go to your room, you to DAN.
Scott(ok hit me)Riese

I see some one with a safety issue I will say something. Don't care if your Paul or David. In Fact I asked David NOT to start his plane by himself like he dose. Upside down, one handed, three blade PA-61. Brett held it the next time.

Scott(Been there done that)Riese

Scott,

You have seriously misunderstood the situation, comments from Ted and myself.

As I understand it, only *after* Rush had stuffed his first Impact did it register with Ted that he had seen Howard flying with an E-Z Just (sic?) handle, this made easier by me telling Ted exactly what failed.

For what it's worth, I am pretty sure Ted did not check Howard's stooge, tail wheel, proper torque on the prop nut, balance of the spinner, the roots of the prop blades, the lines, line clips, etc. In fact, I'll bet you quite a lot of money that Ted failed miserably in his responsibilities to one and all by not insisting on a pull test prior to each flight. **NOT!!**

Look, Howard's a big boy and quite the accomplished CL modeler. One and all can rightly assume he knows exactly what he is doing at all times, that he is doing it to a high standard of safe conduct. He may have lost an excellent model, but the damage went no further.

I will agree that when I see people flop a 61-powered PA model upside down, prime it, fit the glow clip, hitting the prop with one hand while holding the model with the other, I make sure to move away. That they know exactly what they are doing, have obviously never had a problem with this "burping" technique, doesn't affect my thinking: I get outta there!

Ted,

Apologies for a response to my light-hearted jab at you resulting in a question as to your safe and responsible conduct at the CL circles. I never would have guessed my comments to be so misconstrued, but there you have it...