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Twin lead throttle cable

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wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Sun Jul 19, 2009 11:59 am Post subject: Twin lead throttle cable

I'm installing the twin lead throttle cable from Aircraft Spruce:

http://www.aircraftspruce.com/catalog/appages/rotaxdualthrottle.php



It works ok but it lacks the ratcheting lock that my old throttle had. In order to hold idle, I have to keep the adjustable resistance set fairly high to counteract the throttle springs. I find it cumbersome. Anyone have a better solution?

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

jdmcbean(at)kitfoxaircraf
Guest

Posted: Sun Jul 19, 2009 12:40 pm Post subject: Twin lead throttle cable

Luis,

	We have offered this type of cable for some time with the fittings

for the carbs.  We can also offer them with as a vernier type throttle.

Fly Safe !!

John & Debra McBean

Ph 208.337.5111

www.kitfoxaircraft.com 

"The Sky is not the Limit...  It's a Playground" 



--

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Sun Jul 19, 2009 2:41 pm Post subject: Re: Twin lead throttle cable

Luis, the throttle that came with my kit has just the adjustable friction lock.  It took me only a short while to get used to operating it with one hand.  I turn all the friction off for taxi, takeoff and climb out because my hand will be on the throttle all that time anyhow.  When I reduce throttle and level off I can set the throttle for the desired RPM and turn the friction knob with two fingers and thumb to hold it there, then take my hand off the throttle.



When I descend, enter the pattern and land I take the friction off and keep my hand on the throttle again.



I started out flying my kitfox by setting the friction enough to hold the RPM but still be able to push the throttle in...I thought.  On my second or third takeoff  I took my had off to scratch my nose and it slipped back to idle at about 100 feet off the ground and scared the crap out of me.  I thought the engine had done did the dreaded two stroke seizure.

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Tue Jul 21, 2009 3:06 am Post subject: Re: Twin lead throttle cable

Sounds like the spring on your throttle is reversed from mine. On mine, the throttle wants to go wide open. The idea of a friction lock being the only thing keeping the the engine from roaring to full throttle when I'm taxiing around makes me nervous. I've heard of people installing counter balance springs on the old cam operated version of the throttle. Anyone figure out how to do something similar with the twin lead throttle?



 	  Quote: 	
		  I started out flying my kitfox by setting the friction enough to hold the RPM but still be able to push the throttle in...I thought. On my second or third takeoff I took my had off to scratch my nose and it slipped back to idle at about 100 feet off the ground and scared the crap out of me. I thought the engine had done did the dreaded two stroke seizure.

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Tue Jul 21, 2009 5:02 am Post subject: Re: Twin lead throttle cable

 	  Quote: 	
		  Sounds like the spring on your throttle is reversed from mine. On mine, the throttle wants to go wide open. 	




Yes, two stroke Bing 54 carbs.  The carb springs close the throttle.

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Tue Jul 21, 2009 9:03 am Post subject: Re: Twin lead throttle cable

Part of the problem with the throttle spring is that they are relatively short so the tension is quite high at the idle setting. Perhaps a longer spring would even out the tension and keep it reasonable at idle. Any thoughts on the wisdom of modifying the spring mechanism in a 912UL throttle?

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

pchristensen10(at)austin.
Guest

Posted: Tue Jul 21, 2009 9:53 am Post subject: Twin lead throttle cable

What's wrong with no spring?



Pete



---

cliffh(at)outdrs.net
Guest

Posted: Tue Jul 21, 2009 11:02 am Post subject: Twin lead throttle cable

I tried to operate a 912 ULS without the throttle springs. The throttles 

would not stay in syc.

I wound up installing lighter springs. Still have to use the friction lock, 

but it is much easier with the lighter springs.



Floran Higgins

Helena, Mt.

Speedster

912 ULS

---

Vic Baker

Joined: 11 Jan 2006
Posts: 71
Location: Carson City, Nevada

Posted: Tue Jul 21, 2009 12:47 pm Post subject: Twin lead throttle cable

There was a post some months ago concerning a Kitfox crash into the trees 

off the end of a runway.  The carb springs had been changed out for a weaker 

spring.  One of the throttle cables failed and the weaker spring would not 

return the carb to full open.



Consider getting a "vernier" type throttle setup,  Kitfox LLC can fix you 

up.      I've still got the friction lock type throttle with the original 

carb springs.   I'm used to it now, but, for awhile had considered weaker or 

no springs - or the "vernier" type throttle.



Vic Baker

S7 912S Warp

Carson City, Nv

---

_________________
Vic Baker
Series 7
Carson City, Nevada

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Tue Jul 21, 2009 4:57 pm Post subject: Re: Twin lead throttle cable

I definitely would have considered the venier type throttle from Kitfox but I'd already purchased this one from Aircraft Spruce. I didn't realize the implications of the friction style lock until I had it installed.



The instructions for the throttle state that they can not be used to 'push' so some kind of spring is necessary. The crash report on a Kitfox using weaker springs is sobering. I think I'll try finding a way to fit longer springs that will provide the same tension but more consistently. 



Thanks all for the ideas.

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

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