KR> Fwd: Cranks and flywheels

2011-12-27 Thread phillipmathe...@bigpond.com 
Also remember a belted gear reduction will take the loads and not the crank, 
the engine can the produce the RPM it was designed to, and produce the HP it 
is said to.

You can also run a larger prop or more pitch or both.

Phil Matheson
KR2

KR> Fwd: Cranks and flywheels

2011-12-27 Thread Dan Heath 
I would not be so quick to jump to conclusions.  There are many things that
could have played a part in this and no one will know without running a
complete analysis on the damage.  And, then, we may still never know.  The
front bearing is a definite improvement and I would not fly a Corvair engine
without one, at least on a high performance plane.  As for the flywheel,
does the 14# harmonic balancer combined with a prop count for anything
toward a flywheel?  I don't know.

Someone suggested that someone out there should start making cranks.  Well,
someone did.  Brady at Magnificent Machine produced some and I think at
least one is currently in use.  They also eliminated the harmonic balancer.
I was talking to Joe at Revmaster one day about the new engine he was
designing.  He told me that he was getting a crank custom made for his new
engine and that the investment would end up being around a million dollars.
Any takers?

VW cranks used to break until they did the same things that the Corvair
builders are now doing.  I have flown VWs with no extra bearing and with the
so called front bearing like the Force One hub on the Great Plains.  I never
had a crank break.  I wonder how many hours PF Beck has on his Corvair
powered Piet with no front bearing and no broken cranks?

See N64KR at http://KRBuilder.org - Then click on the pics 
See you at the 2012 - KR Gathering in Mt. Vernon, Il – MVN – 40th
Anniversary
There is a time for building and it is almost over.
Daniel R. Heath - Lexington, SC


-Original Message-

Based on the experiences of those who've been there, it seems the big fifth
bearing now being implemented by Corvair builders moderates but doesn't
completely eliminate the effect of the crank bending forces imposed by the
prop

KR> Fwd: Cranks and flywheels

2011-12-27 Thread Tony King 
What does the damage (as I understand it) is not the rotational forces but
the bending force the propeller imposes along the axis of the crank.  These
bending loads are practically non existent in an automotive application and
I'm not sure a flywheel of any weight would make much difference.

The problem arises from fact that the centre of lift of each propeller
blade is quite a way off the axis of the crank.  Averaged over time the
'lift' (perhaps more commonly called thrust) generated by each blade is
close enough to the same, but at any instant, the lift generated by each
blade is not the same as the other blades (due the angle of the propeller
to the airstream - which is not always a right angle, imperfections, slight
differences between blades, etc.), resulting in a force that imposes a
bending load on the crank.

Based on the experiences of those who've been there, it seems the big fifth
bearing now being implemented by Corvair builders moderates but doesn't
completely eliminate the effect of the crank bending forces imposed by the
prop.  Having dismissed the flywheel at the start of my email, it's just
occurred to me that a flywheel at the prop end might help reduce the
bending force by way of the gyroscopic effect of the flywheel acting
against the bending force of the prop.

Sadly I don't have the theoretical background to work out whether a
flywheel of tolerable weight and dimensions could make a useful
contribution.  Any takers?

Cheers,

Tony King
Queensland Australia


> On a theoretical note: Isn't the flywheel meant to store the energy
> imparted to the crank between the power pulses? And if that is the case,
> doesn't a lighter flywheel tend to cause the torsion differential
> between the pulses on the crank to increase versus a heavier flywheel
> which will tend to store the energy longer. This is comparable to what a
> filter circuit does in electronics. If I reduce the capacity of a
> filter, then the ripple voltage will increase, especially under heavy
> loads. Perhaps  a heavier flywheel should be considered, especially in
> an engine which is being increased in its power output. I'd be
> interested in hearing the science on this.
>
>

KR> Fwd: Cranks and flywheels

2011-12-27 Thread Vaughan Thomas 
maybe I should have asked 'gaining some weight and a safety margin isnt such 
a bad idea?' Vaughan Thomas
Hamilton. New Zealand
- Original Message - 
From: "Vaughan Thomas" <v...@xtra.co.nz>
To: "KRnet" <kr...@mylist.net>
Sent: Tuesday, December 27, 2011 11:35 PM
Subject: Re: KR> Fwd: Cranks and flywheels


I,m watching the discussion re corvair engine & broken crankshafts with
interest. (I'd like to get a couple of suitable engines having purchased
WW's conversion manual - but the engines dont exist down here in NZ). It
seems Glen martin might be ontoit as to the flywheel thing, can a prop
achieve the power impulse dampening effect like a flywheel, especially on an
engine intended to run a flywheel or torque converter ?  do 3 bladed props
give a better absorption effect?  Has there been significantly more broken
cranks on 2 or 3 blade propped engines?? Perhaps saving some weight but
gaining  a safety margin isnt such a bad idea? What does the guru WW think
about the broken crank scenario? any comments? Vaughan Thomas
Hamilton. New Zealand
- Original Message - 
From: "Glenn Martin" <rep...@martekmississippi.com>
To: "KRnet" <kr...@mylist.net>
Sent: Tuesday, December 27, 2011 9:24 PM
Subject: KR> Fwd: Cranks and flywheels




 Original Message 
Subject: Cranks and flywheels
List-Post: krnet@list.krnet.org
Date: Tue, 27 Dec 2011 02:16:14 -0600
From: Glenn Martin <rep...@martekmississippi.com>
To: KRnet <kr...@mylist.net>



On 12/26/2011 9:56 PM, Tony King wrote:
>  One significant factor, regardless of which end it's being driven from,
> is
>  that the torsional loads imposed on the crank in an automotive
> application
>  are vastly smaller than those imposed by a propellor spinning at 3000
> rpm.

On a theoretical note: Isn't the flywheel meant to store the energy
imparted to the crank between the power pulses? And if that is the case,
doesn't a lighter flywheel tend to cause the torsion differential
between the pulses on the crank to increase versus a heavier flywheel
which will tend to store the energy longer. This is comparable to what a
filter circuit does in electronics. If I reduce the capacity of a
filter, then the ripple voltage will increase, especially under heavy
loads. Perhaps  a heavier flywheel should be considered, especially in
an engine which is being increased in its power output. I'd be
interested in hearing the science on this.

-- 
Glenn Martin,
KR2 N1333A,
Biloxi, MS

___
Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp
to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net
please see other KRnet info at http://www.krnet.org/info.html






No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.454 / Virus Database: 271.1.1/4103 - Release Date: 12/25/11
19:34:00


___
Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp
to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net
please see other KRnet info at http://www.krnet.org/info.html






No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.454 / Virus Database: 271.1.1/4105 - Release Date: 12/26/11 
19:34:00

KR> Fwd: Cranks and flywheels

2011-12-27 Thread Vaughan Thomas 
I,m watching the discussion re corvair engine & broken crankshafts with 
interest. (I'd like to get a couple of suitable engines having purchased 
WW's conversion manual - but the engines dont exist down here in NZ). It 
seems Glen martin might be ontoit as to the flywheel thing, can a prop 
achieve the power impulse dampening effect like a flywheel, especially on an 
engine intended to run a flywheel or torque converter ?  do 3 bladed props 
give a better absorption effect?  Has there been significantly more broken 
cranks on 2 or 3 blade propped engines?? Perhaps saving some weight but 
gaining  a safety margin isnt such a bad idea? What does the guru WW think 
about the broken crank scenario? any comments? Vaughan Thomas
Hamilton. New Zealand
- Original Message - 
From: "Glenn Martin" <rep...@martekmississippi.com>
To: "KRnet" <kr...@mylist.net>
Sent: Tuesday, December 27, 2011 9:24 PM
Subject: KR> Fwd: Cranks and flywheels




 Original Message 
Subject: Cranks and flywheels
List-Post: krnet@list.krnet.org
Date: Tue, 27 Dec 2011 02:16:14 -0600
From: Glenn Martin <rep...@martekmississippi.com>
To: KRnet <kr...@mylist.net>



On 12/26/2011 9:56 PM, Tony King wrote:
>  One significant factor, regardless of which end it's being driven from, 
> is
>  that the torsional loads imposed on the crank in an automotive 
> application
>  are vastly smaller than those imposed by a propellor spinning at 3000 
> rpm.

On a theoretical note: Isn't the flywheel meant to store the energy
imparted to the crank between the power pulses? And if that is the case,
doesn't a lighter flywheel tend to cause the torsion differential
between the pulses on the crank to increase versus a heavier flywheel
which will tend to store the energy longer. This is comparable to what a
filter circuit does in electronics. If I reduce the capacity of a
filter, then the ripple voltage will increase, especially under heavy
loads. Perhaps  a heavier flywheel should be considered, especially in
an engine which is being increased in its power output. I'd be
interested in hearing the science on this.

-- 
Glenn Martin,
KR2 N1333A,
Biloxi, MS

___
Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp
to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net
please see other KRnet info at http://www.krnet.org/info.html






No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.454 / Virus Database: 271.1.1/4103 - Release Date: 12/25/11 
19:34:00

KR> Fwd: Cranks and flywheels

2011-12-27 Thread Glenn Martin 


 Original Message 
Subject:Cranks and flywheels
List-Post: krnet@list.krnet.org
Date:   Tue, 27 Dec 2011 02:16:14 -0600
From:   Glenn Martin 
To: KRnet 



On 12/26/2011 9:56 PM, Tony King wrote:
>  One significant factor, regardless of which end it's being driven from, is
>  that the torsional loads imposed on the crank in an automotive application
>  are vastly smaller than those imposed by a propellor spinning at 3000 rpm.

On a theoretical note: Isn't the flywheel meant to store the energy
imparted to the crank between the power pulses? And if that is the case,
doesn't a lighter flywheel tend to cause the torsion differential
between the pulses on the crank to increase versus a heavier flywheel
which will tend to store the energy longer. This is comparable to what a
filter circuit does in electronics. If I reduce the capacity of a
filter, then the ripple voltage will increase, especially under heavy
loads. Perhaps  a heavier flywheel should be considered, especially in
an engine which is being increased in its power output. I'd be
interested in hearing the science on this.

-- 
Glenn Martin,
KR2 N1333A,
Biloxi, MS