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Throttle Stops

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carl(at)flyers.freeserve.
Guest

Posted: Thu May 30, 2013 12:23 am Post subject: Throttle Stops

I seem to recall in the early days of Europa that the PFA dictated that we should install a physical throttle stop on the throttle lever (in the cockpit). 

 

I have never really understood the purpose of this as the carburettors have their own stops as IMHO one seems to fight against the other. As soon as you increase the idle RPM using the adjuster screws on the carb, the throttle lever is pulled forward by the cables, moving the lever away from the cockpit stop.

 

We have flown quite happily with the carb stop limiting the slow running with  a gap of about 2 mm between the rear of the throttle lever and the stop block (tufnol). However,  we have just overhauled the carbs and are resetting the balances etc so were wondering if this omission needs to be addressed – it would just be a matter of elongating the holes in the throttle stop.

 

Reading through various articles on Rotax/ Bing carburettor balancing I note that these also stress the need for a cockpit end stop but give no explanation as to why.

 

I’m sure there is a good reason, just need someone to cast some light on this.

 

 

 



 



 



 

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alanb(at)dpy01.co.uk
Guest

Posted: Thu May 30, 2013 12:33 am Post subject: Throttle Stops

Carly,



From the Rotax Installation Manual, Page 2-4.



"The addition of a throttle-closed stop is important to avoid the possibility of excess tension on the throttle cable causing loss of throttle control"

Alan

#0303

On 30 May 2013, at 09:22, Carl Pattinson <carl(at)flyers.freeserve.co.uk (carl(at)flyers.freeserve.co.uk)> wrote:

 	  Quote: 	
		  I seem to recall in the early days of Europa that the PFA dictated that we should install a physical throttle stop on the throttle lever (in the cockpit).

 

I have never really understood the purpose of this as the carburettors have their own stops as IMHO one seems to fight against the other. As soon as you increase the idle RPM using the adjuster screws on the carb, the throttle lever is pulled forward by the cables, moving the lever away from the cockpit stop.

 

We have flown quite happily with the carb stop limiting the slow running with  a gap of about 2 mm between the rear of the throttle lever and the stop block (tufnol). However,  we have just overhauled the carbs and are resetting the balances etc so were wondering if this omission needs to be addressed – it would just be a matter of elongating the holes in the throttle stop.

 

Reading through various articles on Rotax/ Bing carburettor balancing I note that these also stress the need for a cockpit end stop but give no explanation as to why.

 

I’m sure there is a good reason, just need someone to cast some light on this.

 

 



 



 



 



 



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kingsnjan(at)westnet.com.
Guest

Posted: Thu May 30, 2013 2:48 am Post subject: Throttle Stops

<<<<  I’m  sure there is a good reason, just need someone to cast some light on  this.

  

  

 Carl,

  

 My understanding is that if there is no throttle  stop on the throttle lever, it is possible to deform the throttle stops on the  carburettors if one pulls back too hard on the throttle lever.

  

 Cheers

 Kingsley in Oz.

  

  

   [quote][b]

Duncan McFadyean

Joined: 18 Jan 2011
Posts: 224

Posted: Fri May 31, 2013 11:53 pm Post subject: Throttle Stops

Whilst  complying with the LAA requirement for a throttle stop, it's useful to set up  the cables so that the carb stops are reached first, followed closely by the  stop on the throttle lever itself if the lever is deliberately pulled  closed against the throttle lever stop. This limits any excess strain that can  be applied to the cables, but provides a useful facility to temporarily pull  down the idle speed in flight (which in any case will still always be well above  the static setting, as the forward motion drives the prop). As soon as the  deliberate backpressure on the lever is released, 'normal service' is  resumed

 This  facility makes a usefully large addition to rate of descent and is helpful for  landing in to short strips; it's like having an airbrake!

  

 Duncan  McF.

 [quote]   

   --

dg.watts(at)talktalk.net
Guest

Posted: Sat Jun 01, 2013 12:21 am Post subject: Throttle Stops

Duncan,

You've got me there. Surely if you have already pulled the throttle back to the stop on the carb., pulling the lever any more will not make any difference at all. Unless I am missing something.

Dave Watts

G-BXDY Classic Monowheel (Still just short of 2000hrs. But at least we are now flying again from our previously waterlogged airfield, so another week should see us over the magic number, and loving every minute of it)



On 1 Jun 2013, at 08:52, "Duncan & Ami" <ami-mcfadyean(at)talktalk.net (ami-mcfadyean(at)talktalk.net)> wrote:

[quote]   Message   (at)font-face { 	font-family: Helvetica; } (at)font-face { 	font-family: Cambria Math; } (at)font-face { 	font-family: Calibri; } (at)font-face { 	font-family: Consolas; } (at)page WordSection1 {size: 612.0pt 792.0pt; margin: 72.0pt 72.0pt 72.0pt 72.0pt; } P.MsoNormal { 	MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman","serif"; FONT-SIZE: 12pt } LI.MsoNormal { 	MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman","serif"; FONT-SIZE: 12pt } DIV.MsoNormal { 	MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman","serif"; FONT-SIZE: 12pt } A:link { 	COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99 } SPAN.MsoHyperlink { 	COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99 } A:visited { 	COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99 } SPAN.MsoHyperlinkFollowed { 	COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99 } PRE { 	MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Courier New"; FONT-SIZE: 10pt; mso-style-priority: 99; mso-style-link: "HTML Preformatted Char" } SPAN.apple-style-span { 	mso-style-name: apple-style-span } SPAN.HTMLPreformattedChar { 	FONT-FAMILY: "Consolas","serif"; mso-style-priority: 99; mso-style-link: "HTML Preformatted"; mso-style-name: "HTML Preformatted Char" } SPAN.EmailStyle20 { 	FONT-FAMILY: "Calibri","sans-serif"; COLOR: #1f497d; mso-style-type: personal-reply } .MsoChpDefault { 	FONT-SIZE: 10pt; mso-style-type: export-only } DIV.WordSection1 { 	page: WordSection1 }    <![endif]-->   <![endif]-->  Whilst  complying with the LAA requirement for a throttle stop, it's useful to set up  the cables so that the carb stops are reached first, followed closely by the  stop on the throttle lever itself if the lever is deliberately pulled  closed against the throttle lever stop. This limits any excess strain that can  be applied to the cables, but provides a useful facility to temporarily pull  down the idle speed in flight (which in any case will still always be well above  the static setting, as the forward motion drives the prop). As soon as the  deliberate backpressure on the lever is released, 'normal service' is  resumed

 This  facility makes a usefully large addition to rate of descent and is helpful for  landing in to short strips; it's like having an airbrake!

  

 Duncan  McF.

 [quote]   

   --

richard collings

Joined: 08 Jul 2011
Posts: 73
Location: warwickshire england

Posted: Sat Jun 01, 2013 3:41 am Post subject: Throttle Stops

Hi My understanding of this is that if you over travel the throttle lever  when closed you can unseat the cable outer from its carburettor bracket. To  reduce this possibility we are required by LAA to wire lock the outer cable to  that bracket and fit a throttle lever stop in the cabin. Regards Richard

  From: Alan Burrill (alanb(at)dpy01.co.uk) 

 Sent: Thursday, May 30, 2013 9:32 AM

 To: Europa Forum Forum (europa-list(at)matronics.com) 

 Subject: Re: Throttle Stops

 Carly,    

 From the Rotax Installation Manual, Page 2-4.   

 "The addition of a throttle-closed stop is important to avoid the  possibility of excess tension on the throttle cable causing loss of throttle  control"

 Alan

 #0303

  On 30 May 2013, at 09:22, Carl Pattinson <carl(at)flyers.freeserve.co.uk (carl(at)flyers.freeserve.co.uk)>  wrote:

  	  Quote: 	
		           I    seem to recall in the early days of Europa that the PFA dictated that we    should install a physical throttle stop on the throttle lever (in the    cockpit).

   I    have never really understood the purpose of this as the carburettors have    their own stops as IMHO one seems to fight against the other. As soon as you    increase the idle RPM using the adjuster screws on the carb, the throttle    lever is pulled forward by the cables, moving the lever away from the cockpit    stop.

   We    have flown quite happily with the carb stop limiting the slow running    with  a gap of about 2 mm between the rear of the throttle lever and the    stop block (tufnol). However,  we have just overhauled the carbs and are    resetting the balances etc so were wondering if this omission needs to be    addressed – it would just be a matter of elongating the holes in the throttle    stop.

   Reading    through various articles on Rotax/ Bing carburettor balancing I note that    these also stress the need for a cockpit end stop but give no explanation as    to why.

   I’m    sure there is a good reason, just need someone to cast some light on    this.

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nigel_graham(at)m-tecque.
Guest

Posted: Sat Jun 01, 2013 4:11 am Post subject: Throttle Stops

+1

     

     Confused of Southampton

     

     

     On 01/06/2013 09:21, David Watts wrote:

     

     [quote]              Duncan,

       

       

       You've got me there. Surely if you have already pulled the         throttle back to the stop on the carb., pulling the lever any         more will not make any difference at all. Unless I am missing         something.

       

       

       Dave Watts

       G-BXDY Classic Monowheel (Still just short of 2000hrs. But at         least we are now flying again from our previously waterlogged         airfield, so another week should see us over the magic number,         and loving every minute of it)

       

         On 1 Jun 2013, at 08:52, "Duncan & Ami" <ami-mcfadyean(at)talktalk.net (ami-mcfadyean(at)talktalk.net)>         wrote:

         

       

        	  Quote: 	
		                                 Message                      (at)font-face { 	font-family: Helvetica; } (at)font-face { 	font-family: Cambria Math; } (at)font-face { 	font-family: Calibri; } (at)font-face { 	font-family: Consolas; } (at)page WordSection1 {size: 612.0pt 792.0pt; margin: 72.0pt 72.0pt 72.0pt 72.0pt; } P.MsoNormal { 	MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman","serif"; FONT-SIZE: 12pt } LI.MsoNormal { 	MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman","serif"; FONT-SIZE: 12pt } DIV.MsoNormal { 	MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Times New Roman","serif"; FONT-SIZE: 12pt } A:link { 	COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99 } SPAN.MsoHyperlink { 	COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99 } A:visited { 	COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99 } SPAN.MsoHyperlinkFollowed { 	COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99 } PRE { 	MARGIN: 0cm 0cm 0pt; FONT-FAMILY: "Courier New"; FONT-SIZE: 10pt; mso-style-priority: 99; mso-style-link: "HTML Preformatted Char" } SPAN.apple-style-span { 	mso-style-name: apple-style-span } SPAN.HTMLPreformattedChar { 	FONT-FAMILY: "Consolas","serif"; mso-style-priority: 99; mso-style-link: "HTML Preformatted"; mso-style-name: "HTML Preformatted Char" } SPAN.EmailStyle20 { 	FONT-FAMILY: "Calibri","sans-serif"; COLOR: #1f497d; mso-style-type: personal-reply } .MsoChpDefault { 	FONT-SIZE: 10pt; mso-style-type: export-only } DIV.WordSection1 { 	page: WordSection1 }   <![endif]-->   <![endif]-->           Whilst complying with the LAA                 requirement for a throttle stop, it's useful to set up                 the cables so that the carb stops are reached first,                 followed closely by the stop on the throttle lever                 itself if the lever is deliberatelyÂ pulled closed                 against the throttle lever stop. This limits any excess                 strain that can be applied to the cables, but provides a                 useful facility to temporarily pull down the idle speed                 in flight (which in any case will still always be well                 above the static setting, as the forward motion drives                 the prop). As soon as the deliberate backpressure on the                 lever is released, 'normal service' is resumed

           This facility makes a usefully                 large addition to rate of descent and is helpful for                 landing in to short strips; it's like having an                 airbrake!

           Â 

           Duncan McF.

           

         

       	
     [b]

Gilles.Thesee(at)ac-greno
Guest

Posted: Sat Jun 01, 2013 8:12 am Post subject: Throttle Stops

Duncan & Ami a écrit :

 	  Quote: 	
		   Whilst complying with the LAA requirement for a throttle stop, it's 

 useful to set up the cables so that the carb stops are reached first, 

 followed closely by the stop on the throttle lever itself if the lever 

 is deliberately pulled closed against the throttle lever stop. This 

 limits any excess strain that can be applied to the cables, but 

 provides a useful facility to temporarily pull down the idle speed in 

 flight (which in any case will still always be well above the static 

 setting, as the forward motion drives the prop). As soon as the 

 deliberate backpressure on the lever is released, 'normal service' is 

 resumed

 This facility makes a usefully large addition to rate of descent and 

 is helpful for landing in to short strips; it's like having an airbrake!


	


Duncan and all,



In my opinion, an adjustable stop at the throttle lever is important for 

2 things :

- Allowing an easy fine tuning of the idle speed without disturbing 

anything in the engine compartment

- Preventing any stress on the throttle linkage and carb, which is the 

principal cause of changes in idle adjustment and carb synchronization.



I crafted a webpage which may be of interest

http://contrails.free.fr/engine_rotax_stops.php



French only for the moment, but a Frenglish version might appear soon...



FWIW,

Best regards,

-- 

Gilles

http://contrails.free.fr

carl(at)flyers.freeserve.
Guest

Posted: Sun Jun 02, 2013 1:02 am Post subject: Throttle Stops

It does make a difference â€“ on our setup with the engine idling normally (carb throttle arm touching the carb stops) Â we get 2,000 RPM â€“ apply back pressure and the RPM drops to 1,700 RPM â€“ release pressure and the RMP goes back up. The distance between the throttle lever and the backstop is about 2 â€“ 3 mm when no pressure applied.

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of nigel_graham(at)m-tecque.co.uk

Sent: 01 June 2013 13:11

To: europa-list(at)matronics.com

Subject: Re: Throttle Stops

+1

Confused of Southampton

On 01/06/2013 09:21, David Watts wrote:

 	  Quote: 	

Duncan,

You've got me there. Surely if you have already pulled the throttle back to the stop on the carb., pulling the lever any more will not make any difference at all. Unless I am missing something.

Dave Watts

G-BXDY Classic Monowheel (Still just short of 2000hrs. But at least we are now flying again from our previously waterlogged airfield, so another week should see us over the magic number, and loving every minute of it)

On 1 Jun 2013, at 08:52, "Duncan & Ami" <ami-mcfadyean(at)talktalk.net (ami-mcfadyean(at)talktalk.net)> wrote:

 	  Quote: 	

Whilst complying with the LAA requirement for a throttle stop, it's useful to set up the cables so that the carb stops are reached first, followed closely by the stop on the throttle lever itself if the lever is deliberately pulled closed against the throttle lever stop. This limits any excess strain that can be applied to the cables, but provides a useful facility to temporarily pull down the idle speed in flight (which in any case will still always be well above the static setting, as the forward motion drives the prop). As soon as the deliberate backpressure on the lever is released, 'normal service' is resumed

This facility makes a usefully large addition to rate of descent and is helpful for landing in to short strips; it's like having an airbrake!

Duncan McF.

  	  Quote: 	
		   [/b]< Â Â Â Â  - MATRONICS WEB FORUMS via the Web Â Â  --> http://forums.matronics.com[/url]Â Â Â Â Â Â Â Â  - List Contribution Web generous  Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  -Matt http://www.matronics.com/c=[/b] 	

  [quote][b]

Duncan McFadyean

Joined: 18 Jan 2011
Posts: 224

Posted: Sun Jun 02, 2013 1:30 am Post subject: Throttle Stops

Dave,

 You're  missing the elasticity of the throttle stops on the carbs (just bent bits  of mild steel), which are sufficiently springy to drop idle rpm by a couple of  hundred.

  

 DMcF.

 [quote]   

   --

Duncan McFadyean

Joined: 18 Jan 2011
Posts: 224

Posted: Sun Jun 02, 2013 1:47 am Post subject: Throttle Stops

I  should add that it also makes a big difference to the smoothness of engine  shutdown; switch off one mag, pull back on throttle lever just as rpm dips  then switch off the other mag. The engine slows to a graceful  stop.

  

 DMcF.

 [quote]   

   --

Duncan McFadyean

Joined: 18 Jan 2011
Posts: 224

Posted: Sun Jun 02, 2013 1:48 am Post subject: Throttle Stops

Carl,

 Thank  you for understanding my email, no pills needed!

  

 DMcF

 do not  archive

 [quote]   

   --

richard collings

Joined: 08 Jul 2011
Posts: 73
Location: warwickshire england

Posted: Mon Jun 03, 2013 4:16 am Post subject: Throttle Stops

Hi Sorry I have got it wrong again , with the throttle sprung to open the  cabin throttle closed stop is fitted to ensure you donâ€™t over load the levers on  the carburettors by attempting to travel them beyond their stops. By the sound  of it if you can apply extra load to the closed lever and achieve a lower RPM  idle then you must be loading the linkage and taking up any slight play in the  carburettors cross shaft. Not good I think. With regard to not wanting to over  travel the throttle lever when fully open, I fitted a stop in the cabin because  I found that you could unseat the outer cable at the carburettor end by over  traveling the throttle lever to open and did not want to rely on just the wire  locking to stop this.

 Sorry again for my mistake which I realised when I checked the engine  yesterday.

 Regards to all .

 Richard 

 Europa XS  G-CGZV 45Hrs plane flying very well, Pilot rubish.   

    

  From: Duncan & Ami (ami-mcfadyean(at)talktalk.net) 

 Sent: Sunday, June 2, 2013 10:48 AM

 To: europa-list(at)matronics.com (europa-list(at)matronics.com) 

 Subject: RE: Throttle Stops

  



  Carl,

 Thank  you for understanding my email, no pills needed!

  

 DMcF

 do not  archive

 [quote]   

   --

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