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Turnbuckle for super precise linkage ?

johnnyboy2476

Senior Heliman

Queens, New York

Here's an idea I just thought of - how about using turnbuckle for all the linkages? I've been racing RC cars for over ten years and a lot to top racers use titanium turnbuckle to adjust there steering's toe-in and toe-out. Lunsford is a major manufacture of these titanium turnbuckle. How about putting it to heli use?? Won't it be great because you can get much more accuracy with these linkage, since the linkage lenghth can be infinately adjustable. With the standard linkage I find that I need to make one full revolution in or out. I can't make half a revolution since the linkage fit over the ball only one sided. For average flyer like me, I don't see any issues with the stock linkage. But for top F3C guys who demand ultimate precision, this might work. Using turnckle will definately acheive a super level swashplate. So, whatcha guys think about this idea?

04-10-2006 Over year old.
ctd

Senior Heliman

Mile High, USA

Have a link or any pics of them?

ctd

I am sorry my son, If you did not reconize me without my sandals on

04-10-2006 Over year old.
HOMEPAGE  
Guy Martin

rrMaster

UK. Herts

Sounds like a good idea. I find it frustrating that the standard links are restricted to an accuracy of one full turn. Just using the burntuckle links on the blade grips would be sufficient.

04-10-2006 Over year old.
chuckhager

Key Veteran

Clovis, CA

Some guys are already using them. And I think they did mention that they came from the R/C car market. Tower Hobbies carries them. There was some discussion here on Run Ryder about them about six months ago.

04-10-2006 Over year old.
barracudahockey

rrMaster

Jacksonville FL

Zeal or someone used to sell sets for the Nexus for the head and control system a while back but I haven't been able to find them lately.

Andy
AMA 77227
http://www.jaxrc.com

04-10-2006 Over year old.
TMoore

rrMaster

Cookeville, TN

This has been debated at length. If you want to use twist-o-crash links, have at it.

TM

04-10-2006 Over year old.
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trackmagic

Heliman

Washington State USA

like these?

twist-o-crash links
I never had any problems with them.... They are threaded in such a way that if you turn the center with a small wrench one way, they move both links out making the link longer, move it the other direction, & it shortens the link. Beats taking the link off, but either way isnt really much of a problem. They seemed to work fine. I really dont see how they would cause a crash? I mean, a link is a link, so what if it works as a turnbuckle, and has a nut in the middle?

Basically my wife was immature. I'd be in my bath and she'd come in and sink my boats!

04-10-2006 Over year old.
Tommy Z

Key Veteran

Lubbock, Texas

man, that's not a bad idea at all actually. well...start making some, haha.
-Tommy

-Tommy Boy

04-10-2006 Over year old.
TMoore

rrMaster

Cookeville, TN

Turnbuckles are an accident waiting to happen. Why is it that MA put out an AD on these things? It's because they crash helicopters.

If anyone wants to use them it's personal preference. Speaking for me, I'm not going to use them.

TM

04-10-2006 Over year old.
HOMEPAGE  
trackmagic

Heliman

Washington State USA

Im curious....

How is it that these turnbuckle links "crash" helicopters?

I mean a 'threaded link' is the same as a 'threaded link with a nut in the middle', right? What am I failing to understand? Do they self destruct or somehow 'will' the heli to implode?

Seriously though, whats the deal? Do you have a 'link' to the MA 'link' ad? No pun intended of course!

I guess I need to see for myself sometimes. I know its possible there was a batch from a certain manufacture that were known to break, etc. As for the ones I have, they appear to be very strong, and are actually 'machined' from a high grade stainless steel it looks to be.

I dont doubt your claim.

Basically my wife was immature. I'd be in my bath and she'd come in and sink my boats!

04-10-2006 Over year old.
GURUMODS

Senior Heliman

Poughkeepsie,New York

I don't see a weak link in turnbuckles.I have used many titanium buckles from LUNSFORD and it takes a pretty good wack to have one fail.You will have to use new 3mm rod ends obviously.


https://www.lunsfordracing.com/mm5/...egory_Code=TURN

Hooters in gallery

04-10-2006 Over year old.
Angus@HSW

Senior Heliman

ohio

TMoore, what is it about a turnbuckle that causes a crash?... or dont you even know? if anything i would say they would be better, because of there tuneiblity. i just cant understand why you would say such a thing.

04-11-2006 Over year old.
TMoore

rrMaster

Cookeville, TN

In order for a turnbuckle to work it needs to have a LH and a RH thread. I've machined lots of full size turnbuckles for use on aircraft and other devices. In the case of a model there needs to be a center section that allows you to turn the rod to adjust the distance. If it were just a pushrod with a LH and a RH thread, this wouldn't be any different than what we have now but that isn't the case. The center section is the part that changes things because there is now a stress location that is introduced in the center of an otherwise solid rod. The center section is what allows the adjustability. The pushrod usually has rolled threads to maintain strength and integrity of the rod.

The rolled threads are a key component of the rod, especially on a 90 powered heli where the threads terminate at each end of the rod. On cut threads there would be a stress location created at the terminator of the threads. With rolled threaeds this stress location isn't there because the structure of the metal isn't interrupted by the machining process. If you could forge and stress relieve a rod so that the material flow isn't interrupted and the rod had rolled threads this would probably work.

So where can I buy correctly manufactured turnbuckles of the current and correct size for helicopter use that doesn't require me to have to do anything other than screw the links on and snap them in place?

TM

http://www.runryder.net/helicopter/...ght=turnbuckles
http://www.runryder.net/helicopter/...ight=turnbuckle
http://www.runryder.net/helicopter/...ight=turnbuckle

04-11-2006 Over year old.
HOMEPAGE  
chuckhager

Key Veteran

Clovis, CA

Here's what Tower Hobbies has to offer. http://www2.towerhobbies.com/cgi-bi...les&FVPROFIL=++

04-11-2006 Over year old.
Aaron29

Elite Veteran

USA

I think Shannon Davis' video shows the use of turnbuckles on a Tempest.

Maybe he'd care to comment?

04-11-2006 Over year old.
Quick50Nikl

Senior Heliman

Sweden,Sthlm,järfäll a,

I got mine from Zeal for my Nexus.

Assumption is the mother of all . . . . ups

04-11-2006 Over year old.
Guy Martin

rrMaster

UK. Herts

TMoore - good point raised. Do you think the problem would be solved if the rod was tapered at the centre section ?

04-11-2006 Over year old.
TMoore

rrMaster

Cookeville, TN

Guy,

The problem with the MA rods would have been solved with different manufacturing methods and yes, tapering the cross section to a rolled thread would help. If the rod had been forged or roll formed the grain structure would have been insured to flow uniformally and hence be stronger than the original blank.

The reason that turnbuckles work so well in a truck is obvious but if the turnbuckle breaks you just hit the brake and stop or pile into a wall. On a heli, the machine rekits itself or destroys something of value or worse, hits the pilot or all of the afore mentioned items at once. In short, turnbuckles are another failure mode and IMHO, there are enough on a heli already. Adding a turnbuckle for momentary convenience is not warranted. I can't really see the need for the precision that a turnbuckle offers because the rest of the machine doesn't reflect the precision that a turnbuckle provides. When you factor the slop in the links, the servos, the mechanisms and the fact that you track blades by eye, how much precision do you need? On a 2X.4mm rod every turn of the rod is changing the length by .016" of an inch. If you have links that are bi directional this is cut to .008" per half turn. .008" is pretty good considering the application. If you need better you will need something like a turnbuckle but how will that help on a machine where the links are basically right on top of one another just to get decent thread engagement and the proper length? In all the years that I've been flying we've gotten along without turnbuckles. Maybe this time somebody will manufacture a proper one, right now, we're not there.

TM

04-11-2006 Over year old.
HOMEPAGE  
Ronbo

Senior Heliman

Bonney Lake, WA

what about the hangar 9 titanium links on GS aerobatic planes? both my machines, 1/3 to 46% have them. granted, they may not fit our helis, but they work fine on GS doing 3D.

Vbr
Ron
Rapor 90, YS91
MA 99SE, YS80
Blade 400 Spartan, Hitec stock frame

04-11-2006 Over year old.
ESWLFSE

Elite Veteran

Cedar Park, TX

Wouldn't the additional strength of the thicker Ti pushrod make up for the fact that it does not have rolled threads? Could a standard Rocket City link be drilled out .5 mm to thread onto a 3mm pushrod safely?

04-11-2006 Over year old.
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Turnbuckle for super precise linkage ?

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