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wild.blue(at)verizon.net
Guest

Posted: Thu Jan 12, 2006 1:11 pm Post subject: N2

I haven't given this much thought and I realize it's well-trod ground, but please bear with me.  

  

 Logic tells me that in order for the air start to turn the engine the start air or N2 has to be injected ATDC on the power stroke (the only time the valves are closed).  Otherwise, no crank.

  

 So the events go like a so:

  

 The first cylinder to receive cranking air/N2 (ATDC on the power stroke) opens its start poppet valve (because of the start air 50 bar pressure--no cam, just a weak spring) and turns the engine.  The next cylinder in the combustion sequence has been purged on its exhaust stroke and then receives a charge of incoming (intake stroke) and then compressed (compression stroke) combustion mixture from the carburetor (no start air/N2 yet, just what got sucked in through the carburetor), which is now ready to ignite.  The plugs fire a few degrees ATDC (retarded start ignition timing) on the power stroke and ignite the compressed fuel/air mixture.  The small interval between ignition and start air/N2 timing--regardless of whether ignition occurs slightly before or after the introduction of start air/N2--means little or no start air or N2 gets in the cylinder to interfere with combustion.  The engine starts.  Combustion pressure is much greater than 50 bar, so it holds the start air valve closed and the engine runs, regardless of whether or not you keep "cranking."  

  

 The cranking gas (as long its not a fuel) is immaterial.  Shotgun shells work just fine.

  

 No? 

  

 Jerry Painter 

 Wild Blue Aviation 

 425-876-0865 

 http://mysite.verizon.net/res0cs5r/index.html

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viperdoc(at)mindspring.co
Guest

Posted: Thu Jan 12, 2006 2:21 pm Post subject: N2

 	  Quote: 	
		  The cranking gas (as long its not a fuel) is immaterial.  Shotgun shells

work just fine.


	


 	  Quote: 	
		  No? 

Should work fine...as long as you leave the Bird Shot Out! Tthat's the way we used to light our Radials in days long past.
	


Sorry, Could not resist..

DVD

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dabear(at)damned.org
Guest

Posted: Thu Jan 12, 2006 2:52 pm Post subject: N2

Jerry,



I'd agree with you based on logic.  However,  I've been able to start

the Housai engine on N2, but on both my M14Ps, neither would start on

N2.  Can't tell you why, they just don't. 



Dabear

Jerry Painter wrote:



 	  Quote: 	
		   I haven't given this much thought and I realize it's well-trod ground,

 but please bear with me.  

  

 Logic tells me that in order for the air start to turn the engine the

 start air or N2 has to be injected ATDC on the power stroke (the only

 time the valves are closed).  Otherwise, no crank.

  

 So the events go like a so:

  

 The first cylinder to receive cranking air/N2 (ATDC on the power

 stroke) opens its start poppet valve (because of the start air 50 bar

 pressure--no cam, just a weak spring) and turns the engine.  The next

 cylinder in the combustion sequence has been purged on its exhaust

 stroke and then receives a charge of incoming (intake stroke) and then

 compressed (compression stroke) combustion mixture from the carburetor

 (no start air/N2 yet, just what got sucked in through the carburetor),

 which is now ready to ignite.  The plugs fire a few degrees ATDC

 (retarded start ignition timing) on the power stroke and ignite the

 compressed fuel/air mixture.  The small interval between ignition and

 start air/N2 timing--regardless of whether ignition occurs slightly

 before or after the introduction of start air/N2--means little or no

 start air or N2 gets in the cylinder to interfere with combustion. 

 The engine starts.  Combustion pressure is much greater than 50 bar,

 so it holds the start air valve closed and the engine runs, regardless

 of whether or not you keep "cranking." 

  

 The cranking gas (as long its not a fuel) is immaterial.  Shotgun

 shells work just fine.

  

 No? 

  

 Jerry Painter 

 Wild Blue Aviation 

 425-876-0865 

 http://mysite.verizon.net/res0cs5r/index.html

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cjpilot710(at)aol.com
Guest

Posted: Thu Jan 12, 2006 5:43 pm Post subject: N2

It might be  technique.  I didn't have any problem using N2 in mine (M-14P) the few  times I needed to.  I did find if I held the throttle full open during the  start AND of course closed it to idle when she caught, she'd start  fine.

  

 Pappy

  

 Jerry,



I'd agree with you based on  logic.  However,  I've been able to start

the Housai engine on N2,  but on both my M14Ps, neither would start on

N2.  Can't tell you why,  they just don't. 



Dabear

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brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Thu Jan 12, 2006 8:21 pm Post subject: N2

DaBear wrote:

 	  Quote: 	
		   

 

 Jerry,

 

 I'd agree with you based on logic.  However,  I've been able to start

 the Housai engine on N2, but on both my M14Ps, neither would start on

 N2.  Can't tell you why, they just don't. 


	


Timing, my boy. Timing.



Jerry is right on the timing of the engine. But I also think there is

something else going on WRT N2 getting into the induction system. It is

the only way I can think of that the engine wouldn't start.



-- 

Brian Lloyd                         2243 Cattle Dr.

brian-yak at lloyd dot com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

- Antoine de Saint-Exupery

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_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

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