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  #21  
Old 06-13-2017, 09:23 PM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
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Power at idle and pitch for speed, got that, Jolly er Roger, whoever you are driven to be, thanks for your expertise. I'm newish to the ELSA world. Lots to learn and refresh on. Know it all or not, you come off as wanting to inform us newbies with thoughtful referenced material. Hope the Blog police lighten up on you and reconsider your value to us. Doug in IL

Quote:
Originally Posted by Jolly View Post
The stick controls air speed on approach and landing and the throttle altitude or glide slope. All these articles say the same. There are hundreds more.
Landing in your chosen idle rpm speed is controlled by the stick and the nose attitude.

http://www.boldmethod.com/learn-to-f...-a-glideslope/


https://www.pilotworkshop.com/tips/f...oach_speed.htm

http://www.110knots.com/airspeed-and...ls-of-thought/

http://flycasey.com/landing-pitch-and-power/

Quote from Beyond PPL book on flying:

"In days of yore, instructors always taught that on the approach you should control airspeed with pitch and maintain the correct glide slope with the throttle.
The technique taught was (and still is) a good device for getting students to co-ordinate properly their applications of pitch and throttle."
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  #22  
Old 06-14-2017, 06:03 AM
Fast Eddie B Fast Eddie B is online now
 
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Location: Mineral Bluff, GA
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I've done BING carb synch dozens of times, albeit mostly on BMW airhead motorcycles.

Two different adjustments are in play:

1) At idle, the throttle cables should have enough "play" that the idle is determined solely by the position of the idle screws. Get that right first. Make absolutely sure the throttle arms are firmly against the idle screws at idle. If not, adjust the barrel adjuster involved to make sure they both are.

2) At whatever midrange setting you choose -3,500 seems about right - it's the cables that determine the synch. Adjustment for that is with the barrel adjusters. As long as that adjustment does not eliminate the "play" in the cables at idle - it can - idle speed should not be affected by the midrange synch.

Finally, make sure your "chokes" are fully off. On my Sky Arrow the "choke" cables are really long and the return springs seem marginal at best to close them all the way against the stop. I think I'll look for slightly stronger return springs while I have everything apart for my annual.

As an aside, "choke" is put in quotes because the BINGS don't utilize a choke, per sé. Rather than "choke" the flow of air to the carb to enrichen the mixture, the BINGs use a separate starter circuit. I think most pilots/owners are aware of this, but some newbies might not be.

Last edited by Fast Eddie B : 06-14-2017 at 06:06 AM.
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  #23  
Old 06-14-2017, 10:43 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Fast Eddie B View Post

1) At idle, the throttle cables should have enough "play" that the idle is determined solely by the position of the idle screws. Get that right first. Make absolutely sure the throttle arms are firmly against the idle screws at idle. If not, adjust the barrel adjuster involved to make sure they both are.
This is not relevant for the carbs installed on a Rotax 912

The cables on a 912 are under maximum tension when the throttle is at idle so no slack can be provided.

Also, Rotax specifically specifies that a secondary idle stop must be used because the carb. stop that hits the screw will flex under load when someone is pulling on the throttle to the idle position.

For the RV-12, the stops are small blocks that slip onto the cable and get clamped with a set screw. they are adjusted so that they bump the barrel adjuster when the throttle is at idle position.

They are supplied with the throttle control.
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  #24  
Old 06-14-2017, 12:58 PM
Fast Eddie B Fast Eddie B is online now
 
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Quote:
Originally Posted by rvbuilder2002 View Post
This is not relevant for the carbs installed on a Rotax 912

The cables on a 912 are under maximum tension when the throttle is at idle so no slack can be provided.
Scott,

You are, of course, right. My Sky Arrow is the same, as I assume all ROTAX 912 installations are.

I blame, in no particular order...

1) Negative transfer from my motorcycle carb syncing days.

2) Mature Onset Dyslexia.

Thanks for setting the record straight.

Last edited by Fast Eddie B : 06-14-2017 at 01:11 PM.
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  #25  
Old 06-14-2017, 03:48 PM
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DonFromTX DonFromTX is offline
 
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I have not yet even pulled the cowlings, but cannot understand your post,
is there a reference that would make it more clear to me?
I am installing a Vans Vernier throttle, but in the meantime I am entertaining my airport bums by pulling the throttle out, letting go and watching in disbelief as it goes to full throttle! (us old people are quite easy to entertain actually)

Quote:
Originally Posted by rvbuilder2002 View Post
This is not relevant for the carbs installed on a Rotax 912

The cables on a 912 are under maximum tension when the throttle is at idle so no slack can be provided.

Also, Rotax specifically specifies that a secondary idle stop must be used because the carb. stop that hits the screw will flex under load when someone is pulling on the throttle to the idle position.

For the RV-12, the stops are small blocks that slip onto the cable and get clamped with a set screw. they are adjusted so that they bump the barrel adjuster when the throttle is at idle position.

They are supplied with the throttle control.
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  #26  
Old 06-14-2017, 08:06 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by DonFromTX View Post
I have not yet even pulled the cowlings, but cannot understand your post,
is there a reference that would make it more clear to me?
I am installing a Vans Vernier throttle, but in the meantime I am entertaining my airport bums by pulling the throttle out, letting go and watching in disbelief as it goes to full throttle! (us old people are quite easy to entertain actually)
The engine install section of the KAI covers it.
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  #27  
Old 06-14-2017, 09:17 PM
RFSchaller RFSchaller is online now
 
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My first encounter with th ROTAX 912 was on a Searey I built. On that setup the springs were set to shut the throttle. I think the RV-12 is a much safer design (spring to WOT).
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  #28  
Old 06-14-2017, 09:50 PM
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DonFromTX DonFromTX is offline
 
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Thanks Scott, I had not explored that yet.

Quote:
Originally Posted by rvbuilder2002 View Post
The engine install section of the KAI covers it.
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A&P, PP-SEL, Pathological Flier, EAA Technical Counselor
EAA Chapter 595 President,http://www.595.eaachapter.org/index.htm
Retired US Army Officer
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  #29  
Old 06-14-2017, 10:21 PM
DaveWelch DaveWelch is offline
 
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Quote:
Originally Posted by RFSchaller View Post
My first encounter with th ROTAX 912 was on a Searey I built. On that setup the springs were set to shut the throttle. I think the RV-12 is a much safer design (spring to WOT).
It makes sense I suppose if you have a cable failure in cruise. It's a real pain when you're trying to slow down and get down to a short strip as the RPMs creep up on you.
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  #30  
Old 06-14-2017, 11:14 PM
RFSchaller RFSchaller is online now
 
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On my first home built I had a Continental O-200. I installed springs to make the throttle go wide open if the cable snapped. Well one day it did on the ground which sent me rocketing toward the FBO lobby window. Killing the mags stopped it. I limped back to the hangar using mixture for a throttle. Sometimes getting experience really sucks!
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