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Corvair 5th bearing ...Nitriding

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rvickski(at)yahoo.com
Guest

Posted: Fri Mar 21, 2008 5:19 am Post subject: Corvair 5th bearing ...Nitriding

My apologies to the list but since this was posted

here I feel I must respond here.



Thank you Pramod for sharing your knowledge and

insight on a subject many perceive as a black art,

namely heat treating metals.



I take issue with your statement; 

"In my opinion, a fifth bearing is a feel good

solution

 if you are trying to increase the fatigue strength."



First of all the strength of a shaft is what it is,

whether it is nitrided or not, it is what it is.   



The concept of a fifth bearing addresses the issue of

complex loading we place on the crankshaft by

cantilevering a propellor by four or more inches away

from the existing 3/4 inch wide bearing. A properly

implemented fifth bearing design will reduce the

magnitude of stress imparted to the shaft and allow it

to perform under conditions that fall below, hopefully

well below the threshold of fatigue limit. 



Your idea that a crankshaft with a larger cross

section is a better solution than a fifth bearing is

convenient for the armchair engineer. But until you or

someone else produces one and addresses the logistical

complications the idea is counter- productive to

todays reality. Besides, in order to "feel good" about

this new crankshaft it would need a longer prop end

bearing.



The designers of the Jabiru, Continental and Lycoming

engines must really want to feel good about their

engines judging from the length of bearings they

choose to use!



In order to achieve a compact, light and appropriate

design I have chosen to work within the limitations of

the engine as designed by GM.



For those interested in my approach to the corvair

crankshaft issue please visit my site.



roysgarage.com 



Roy, 701 plans, but currently off on a tangent!



Experience is the mother of knowledge.' Cervantes





Time: 09:25:22 AM PST US

From: Pramod Kotwal <pramodkotwal(at)yahoo.com>

Subject: Re: Re: Corvair 5th bearing ...

 Nitriding



Nitriding



Nitrogen is diffused into the metal matrix during

 nitriding.

This introduces compressive stresses in the area where

 the nitrogen is diffused.

The depth of this diffusion zone is generally referred

 to as case depth.

The compressive stresses oppose the bending stresses

  at the  opposing end  and

lower the  resulting stresses.

Fatigue strength is the ability of a part to withstand

 bending stresses over a

number of load cycles.



Lowering bending stresses increases the number of load

 cycles that a part can withstand.

Remember that these load cycles are cumulative over

 the life of a part.



Nitriding can achieve only a limited increase of the

 number of survivable load

cycles if the loads are very high and if the part has

 already experienced a large

number of load cycles under heavy loads.



A fifth bearing will eliminate deflections of the

 crankshaft but it will not reduce

the bending force exerted by the connecting rod. So

 the bending stresses

will not be lowered.  Hence the contribution of the

 fifth bearing towards increasing

the fatigue strength of a crankshaft remains to be

 seen. A crankshaft with

a larger cross section is a better solution. 



In my opinion, a fifth bearing is a feel good solution

 if you are trying to increase

the fatigue strength.   



Pramod Kotwal

Nitron, Inc.

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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n801bh(at)netzero.com
Guest

Posted: Fri Mar 21, 2008 1:11 pm Post subject: Corvair 5th bearing ...Nitriding

I looked over what Roy is doing and it is a GREAT idea. I have been a machinist almost my whole life and his work is excellent, his concept sound and his approach to the problem the best fix, short of redesigning the complete motor. I had people write on some lists that my V-8 Zenith would not fly because of various wifes tales. To them I say,,,, Seeya... 

I want this archived too.

Ben Haas

N801BH

www.haaspowerair.com



-- Roy Szarafinski <rvickski(at)yahoo.com> wrote:

--> Zenith-List message posted by: Roy Szarafinski <rvickski(at)yahoo.com>



My apologies to the list but since this was posted

here I feel I must respond here.



Thank you Pramod for sharing your knowledge and

insight on a subject many perceive as a black art,

namely heat treating metals.



I take issue with your statement; 

"In my opinion, a fifth bearing is a feel good

solution

if you are trying to increase the fatigue strength."



First of all the strength of a shaft is what it is,

whether it is nitrided or not, it is what it is.   



The concept of a fifth bearing addresses the issue of

complex loading we place on the crankshaft by

cantilevering a propellor by four or more inches away

from the existing 3/4 inch wide bearing. A properly

implemented fifth bearing design will reduce the

magnitude of stress imparted to the shaft and allow it

to perform under conditions that fall below, hopefully

well below the threshold of fatigue limit. 



Your idea that a crankshaft with a larger cross

section is a better solution than a fifth bearing is

convenient for the armchair engineer. But until you or

someone else produces one and addresses the logistical

complications the idea is counter- productive to

todays reality. Besides, in order to "feel good" about

this new crankshaft it would need a longer prop end

bearing.



The designers of the Jabiru, Continental and Lycoming

engines must really want to feel good about their

engines judging from the length of bearings they

choose to use!



In order to achieve a compact, light and appropriate

design I have chosen to work within the limitations of

the engine as designed by GM.



For those interested in my approach to the corvair

crankshaft issue please visit my site.



roysgarage.com 



Roy, 701 plans, but currently off on a tangent!



Experience is the mother of knowledge.' Cervantes





Time: 09:25:22 AM PST US

From: Pramod Kotwal <pramodkotwal(at)yahoo.com>

Subject: Re: Re: Corvair 5th bearing ...

Nitriding



Nitriding



Nitrogen is diffused into the metal matrix during

nitriding.

This introduces compressive stresses in the area where

the nitrogen is diffused.

The depth of this diffusion zone is generally referred

to as case depth.

The compressive stresses oppose the bending stresses

 at the  opposing end  and

lower the  resulting stresses.

Fatigue strength is the ability of a part to withstand

bending stresses over a

number of load cycles.



Lowering bending stresses increases the number of load

cycles that a part can withstand.

Remember that these load cycles are cumulative over

the life of a part.



Nitriding can achieve only a limited increase of the

number of survivable load

cycles if the loads are very high and if the part has

already experienced a large

number of load cycles under heavy loads.



A fifth bearing will eliminate deflections of the

crankshaft but it will not reduce

the bending force exerted by the connecting rod. So

the bending stresses

will not be lowered.  Hence the contribution of the

fifth bearing towards increasing

the fatigue strength of a crankshaft remains to be

seen. A crankshaft with

a larger cross section is a better solution. 



In my opinion, a fifth bearing is a feel good solution

if you are trying to increase

the fatigue strength.   



Pramod Kotwal

Nitron, Inc.

========================bsp;      - The Zenith-List Email Forum -<========================;           &nbsp========================bsp;         - List Contrib            ======================================================== 



_____________________________________________________________

Click here and get the professional resume help you need.

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Ron Lendon

Joined: 10 Jan 2006
Posts: 685
Location: Clinton Twp., MI

Posted: Fri Mar 21, 2008 2:31 pm Post subject: Re: Corvair 5th bearing ...Nitriding

Ben,  I couldn't agree with you more.  I am a machinist / welder also but Roy is going to build one for me.  I was so excited when I went to see it the first time that I wanted to setup an engineering fund and get this thing in the air.



I have rethought that idea and decided that I just wanted one for myself.



Come on down to SnF 2008 and see it for yourself.

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

_________________
Ron Lendon
WW Corvair with Roy's Garage 5th bearing
CH 601 XLB
N601LT - Flying
http://www.mykitlog.com/rlendon
Corvair Engine Prints:
https://sites.google.com/site/corvairenginedata/

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Fri Mar 21, 2008 4:18 pm Post subject: Re: Corvair 5th bearing ...Nitriding

Roy, I'm surprised you would even need to post to clarify this. Seems like a no-brainer that a 5th bearing would take a lot of stress off crankshaft.



I can't believe anyone would even argue you or WW on this. It just makes sense.



 	  rvickski(at)yahoo.com wrote: 	
		  My apologies to the list but since this was posted

here I feel I must respond here.



Thank you Pramod for sharing your knowledge and

insight on a subject many perceive as a black art,

namely heat treating metals.



I take issue with your statement; 

"In my opinion, a fifth bearing is a feel good

solution

 if you are trying to increase the fatigue strength."



First of all the strength of a shaft is what it is,

whether it is nitrided or not, it is what it is.   



The concept of a fifth bearing addresses the issue of

complex loading we place on the crankshaft by

cantilevering a propellor by four or more inches away

from the existing 3/4 inch wide bearing. A properly

implemented fifth bearing design will reduce the

magnitude of stress imparted to the shaft and allow it

to perform under conditions that fall below, hopefully

well below the threshold of fatigue limit. 



Your idea that a crankshaft with a larger cross

section is a better solution than a fifth bearing is

convenient for the armchair engineer. But until you or

someone else produces one and addresses the logistical

complications the idea is counter- productive to

todays reality. Besides, in order to "feel good" about

this new crankshaft it would need a longer prop end

bearing.



The designers of the Jabiru, Continental and Lycoming

engines must really want to feel good about their

engines judging from the length of bearings they

choose to use!



In order to achieve a compact, light and appropriate

design I have chosen to work within the limitations of

the engine as designed by GM.



For those interested in my approach to the corvair

crankshaft issue please visit my site.



roysgarage.com 



Roy, 701 plans, but currently off on a tangent!



Experience is the mother of knowledge.' Cervantes





Time: 09:25:22 AM PST US

From: Pramod Kotwal <pramodkotwal>

Subject: Re: Re: Corvair 5th bearing ...

 Nitriding



Nitriding



Nitrogen is diffused into the metal matrix during

 nitriding.

This introduces compressive stresses in the area where

 the nitrogen is diffused.

The depth of this diffusion zone is generally referred

 to as case depth.

The compressive stresses oppose the bending stresses

  at the  opposing end  and

lower the  resulting stresses.

Fatigue strength is the ability of a part to withstand

 bending stresses over a

number of load cycles.



Lowering bending stresses increases the number of load

 cycles that a part can withstand.

Remember that these load cycles are cumulative over

 the life of a part.



Nitriding can achieve only a limited increase of the

 number of survivable load

cycles if the loads are very high and if the part has

 already experienced a large

number of load cycles under heavy loads.



A fifth bearing will eliminate deflections of the

 crankshaft but it will not reduce

the bending force exerted by the connecting rod. So

 the bending stresses

will not be lowered.  Hence the contribution of the

 fifth bearing towards increasing

the fatigue strength of a crankshaft remains to be

 seen. A crankshaft with

a larger cross section is a better solution. 



In my opinion, a fifth bearing is a feel good solution

 if you are trying to increase

the fatigue strength.   



Pramod Kotwal

Nitron, Inc.

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

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