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<1351918635.64043.YahooMailNeo@web125502.mail.ne1.yahoo.com> Date: Fri, 2 Nov 2012 21:57:15 -0700 (PDT) From: Kenneth Johnson Reply-To: Kenneth Johnson Subject: Re: [FlyRotary] Re: flow path in conventional radiator To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-1546730761-528122309-1351918635=:64043" ---1546730761-528122309-1351918635=:64043 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Thanks Tracy and others that have responded,=0A=0AAt times, my words have n= ot described what I had been thinking.=A0 That is why it is often said that= a picture is worth a thousand words.=A0 If one could imagine the mouth of = a shark as the opening of the cowl and the gills as the exits, we might obt= ain a more accurate picture.=A0 If air would flow in the bottom front of th= e cowl through the radiator and exit near the top rear sides of the cowl, j= ust in front of the firewall and windscreen, we should have a pretty direct= flow of air.=A0 =0A=0A=0AI would agree that tests would have to be made to= see if air is actually flowing from a high pressure area to a low pressure= area.=A0 In fact, that is Paul Lamar recommends continually through his bo= ok with the use of a manometer.=A0 Paul also discusses diffusers both for a= ir intake and exiting the cowl.=0A=0A=0ACertainly, it is possible to take o= ff with a cooler engine.=A0 But I would imagine that heating the oil up to = provide the best lubrication would be the best practice to preserve engine = parts.=0A=0AThe amount of air flowing over the radiator needs to affect coo= ling.=A0 And because the Zenith 801 is a very slow plane during take-off an= d initial climb out, and because of its angle of attack, air flow might nee= d to be different than other faster planes. =0A=0A=0AI have talked with pil= ots of other bush type planes and their general thoughts are that climb out= s to over take obstacles take a very short time and periods of level flight= during extended climb outs tend to cool an engine.=A0 My thoughts would su= ggest that it is better to cool the engine best during take off and reduce = cooling as the airplane picks up speed.=A0 The speed of the airplane causes= more air to pass over the radiator and the engine speed is reduced, reduci= ng heat.=0A=0A=0AThe truth is, as was stated, that I would actually have to= build a plane and test it to prove its effectiveness.=A0 At this point, I = have created a large opening below my prop that ducts air through my radiat= or and out a diffuser below my airplane.=A0 As I test this option this comi= ng year, I will see if that is effective.=0A=0AIt seems we all have differe= nt planes in which we are using the rotary engine.=A0 Different systems wit= h different applications produce different results.=0A=0AThanks for your co= mments.=0A=0Aken johnson=0A=0A=0A=0A=0A=0A=0A=0A=0A=0A=0A=0A=A0 =0A=0A=0A= =0A________________________________=0A From: Tracy =0AT= o: Rotary motors in aircraft =0ASent: Wednesd= ay, October 31, 2012 11:38 AM=0ASubject: [FlyRotary] Re: flow path in conve= ntional radiator=0A =0A=0AHi Ken,=0A=A0 =A0 Will check out Paul's book when= I get a chance but Paul & I have had many discussions on cooling in the pa= st. =A0 =A0I've read much of the same source material that he uses (K&W for= one example) but we frequently disagree on the interpretation of it. =A0= =0A=0AI may have misinterpreted one detail in your original description of = the proposed system. =A0When you used the term anterior I think I pictured = posterior. =A0 The term Front makes it clearer. =A0 I assume you are aiming= at the idea of the 'wedge diffuser'. =A0=A0=0A=0A=A0Still, I think your sc= heme involves more turns and twists in the airflow than is necessary or adv= antageous. =A0You can't find a more natural place to take in high pressure = air than the front of the cowl. =A0It has the added advantage of not adding= any frontal area to the airframe. =A0Even a 100 MPH airplane benefits from= drag reduction. =A0 I think Getting the air cleanly out of the upper sides= of the cowl might be harder than it sounds. =A0 To explain why is a much l= onger discussion. =A0=0A=0AAgain, I realize that compromises must be made s= o sometimes the theoretical "best" system isn't practical so you may have t= o sacrifice a bit of drag.=0A=0AOn short grass strips you usually have the = advantage of no long taxi or waiting for traffic. =A0 In this situation, do= n't wait for the engine to reach normal operating temps. =A0Take off at min= imum oil temp (I use 120 F) and you will be far above the trees by the time= temps reach max. even on a hot day.=0A=0ATracy=0A=0ASent from my iPad=0A= =0AOn Oct 31, 2012, at 9:03 AM, Kenneth Johnson wro= te:=0A=0A=0ATracy,=0A>Sorry to get back to you so late, but am now just get= ting caught up on emails.=A0 When I have free time, I am usually out in my = garage working on the plane.=A0 If you have not read "How to Cool Your Wank= el" by Paul Lamar, I would recommend it.=A0 It would be worth your time.=A0= =A0=0A>=0A>=0A>The suggestion to flow air from the bottom up was not made b= y Paul, but was my thoughts regarding the airplane I am building.=A0 The Ze= nith 801 is the four passenger high wing STOL bush-type plane.=A0 It's top = speed is 110 MPH.=A0 It's primary purpose is getting in and out of short, g= rass strips.=A0 Where engine cooling is most needed is on short runway take= -off with high obstacles such as trees at the runway's end.=A0 Stall speed = is about 40 MPH.=A0 This just means there is very little air flowing throug= h the cooling system on take-off.=A0=A0 The airplane is at a high angle of = attack until obstacles are cleared.=A0 And again, at this high angle of att= ack, cooling flow is different and airspeed is slow.=0A>Having the cowl ope= ning on the bottom front of the cowl where air flows directly through the r= adiators and having outlets on the top sides of the cowl would allow air to= flow best when it is most needed to cool the engine.=A0 At flat and level = flying, the air would still flow, but the higher speed would provide more c= ooling.=A0=A0=0A>=0A>=0A>What makes this plane unique is it is not an RV wh= ere one is flying at 170 knots and has a mile long runway.=A0=A0=A0=0A>=0A>= =0A>Please read Paul's book and give me your thoughts.=A0 Thanks for your c= omments.=A0 =0A>=0A>=0A>=0A>Ken Johnson=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>= ________________________________=0A> From: Tracy =0A>To= : Rotary motors in aircraft =0A>Sent: Wednesd= ay, October 24, 2012 12:21 PM=0A>Subject: [FlyRotary] Re: flow path in conv= entional radiator=0A> =0A>=0A>=0A>On Oct 24, 2012, at 10:14 AM, Kenneth Joh= nson wrote:=0A>=0A>> A more efficient design would= =A0 have intake air entering the bottom anterior of the the cowl and to pas= s through the radiator.=A0 As this air is heated by the radiator it rises = and should exit the top sides of the cowl.=A0 No one has done that because = of the risk of engine oil on the windshield.=0A>=0A>=0A>I haven't read Paul= 's book but if this is an example of his suggestions, I wouldn't have much = confidence in it.=A0 =0A>=0A>Two basic rules of thumb for A/C cooling syste= ms are:=0A>=0A>1. Turning high speed air is hard to do and loss prone energ= y wise.=0A>=0A>2.=A0 The pressure represented by convection of rising hot = air is not significant=A0 and can safely be ignored for our purposes.=A0 = =0A>=0A>Tracy=0A>--=0A>Homepage:=A0 http://www.flyrotary.com/=0A>Archive an= d UnSub:=A0 http://mail.lancaironline.net:81/lists/flyrotary/List.html=0A>= =0A>=0A> ---1546730761-528122309-1351918635=:64043 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Thanks Tra= cy and others that have responded,

=
At times, my words have not described what I had been thinking.&= nbsp; That is why it is often said that a picture is worth a thousand words= .  If one could imagine the mouth of a shark as the opening of the cow= l and the gills as the exits, we might obtain a more accurate picture. = ; If air would flow in the bottom front of the cowl through the radiator an= d exit near the top rear sides of the cowl, just in front of the firewall and windscreen, we should have a pretty direct flow of air. 

I would agree that tests wo= uld have to be made to see if air is actually flowing from a high pressure = area to a low pressure area.  In fact, that is Paul Lamar recommends c= ontinually through his book with the use of a manometer.  Paul also di= scusses diffusers both for air intake and exiting the cowl.

Certainly, it is possible to take = off with a cooler engine.  But I would imagine that heating the oil up= to provide the best lubrication would be the best practice to preserve eng= ine parts.

The amount of= air flowing over the radiator needs to affect cooling.  And because t= he Zenith 801 is a very slow plane during take-off and initial climb out, a= nd because of its angle of attack, air flow might need to be different than= other faster planes.

<= span> I have talked with pilots of other bush type planes and their general= thoughts are that climb outs to over take obstacles take a very short time= and periods of level flight during extended climb outs tend to cool an eng= ine.  My thoughts would suggest that it is better to cool the engine b= est during take off and reduce cooling as the airplane picks up speed. = ; The speed of the airplane causes more air to pass over the radiator and t= he engine speed is reduced, reducing heat.

The truth is, as was stated, th= at I would actually have to build a plane and test it to prove its effectiv= eness.  At this point, I have created a large opening below my prop th= at ducts air through my radiator and out a diffuser below my airplane. = ; As I test this option this coming year, I will see if that is effective.<= /span>

It seems we all have dif= ferent planes in which we are using the rotary engine.  Different systems with different applications produce different results.

Thanks for your comments.

ken johnson





=


<= /div>


&nb= sp;

From: Tracy <rwstracy@gmail.com>
To: Rotary motors in aircraft &= lt;flyrotary@lancaironline.net>
Sent: Wednesday, October 31, 2012 11:38 AM
Subject: [FlyRotary] Re: flow path in co= nventional radiator

=0A
Hi Ken,
    Will check out Paul's book when I ge= t a chance but Paul & I have had many discussions on cooling in the pas= t.    I've read much of the same source material that he uses (K&= amp;W for one example) but we frequently disagree on the interpretation of = it.  

I may have misinterpreted one detail in= your original description of the proposed system.  When you used the = term anterior I think I pictured posterior.   The term Front makes it = clearer.   I assume you are aiming at the idea of the 'wedge diffuser'= .   

 Still, I think your scheme in= volves more turns and twists in the airflow than is necessary or advantageo= us.  You can't find a more natural place to take in high pressure air = than the front of the cowl.  It has the added advantage of not adding = any frontal area to the airframe.  Even a 100 MPH airplane benefits from drag reduction.   I think= Getting the air cleanly out of the upper sides of the cowl might be harder= than it sounds.   To explain why is a much longer discussion.  <= /div>

Again, I realize that compromises must be made so = sometimes the theoretical "best" system isn't practical so you may have to = sacrifice a bit of drag.

On short grass strips you= usually have the advantage of no long taxi or waiting for traffic.   = In this situation, don't wait for the engine to reach normal operating temp= s.  Take off at minimum oil temp (I use 120 F) and you will be far abo= ve the trees by the time temps reach max. even on a hot day.

=
Tracy

Sent from my iPad

On Oct 31, 2012, at= 9:03 AM, Kenneth Johnson <kjohnsondds@yahoo.com> wrote:=

Tracy,
Sorry to get back to you so l= ate, but am now just getting caught up on emails.  When I have free ti= me, I am usually out in my garage working on the plane.  If you have n= ot read "How to Cool Your Wankel" by Paul Lamar, I would recommend it. = ; It would be worth your time.  

The=0A suggestion to flow air from the bottom up was not made by Paul, = but was my thoughts regarding the airplane I am building.  The Zenith = 801 is the four passenger high wing STOL bush-type plane.  It's top sp= eed is 110 MPH.  It's primary purpose is getting in and out of short, = grass strips.  Where engine cooling is most needed is on short runway = take-off with high obstacles such as trees at the runway's end.  Stall= speed is about 40 MPH.  This just means there is very little air flow= ing through the cooling system on take-off.   The airplane is at = a high angle of attack until obstacles are cleared.  And again, at thi= s high angle of attack, cooling flow is different and airspeed is slow.
Having the cowl opening on the bottom front of the cowl=0A wh= ere air flows directly through the radiators and having outlets on the top = sides of the cowl would allow air to flow best when it is most needed to co= ol the engine.  At flat and level flying, the air would still flow, bu= t the higher speed would provide more cooling.  

<= span>
What makes this plane unique is it is not an RV wher= e one is flying at 170 knots and has a mile long runway.   <= /span>

Please read Paul's book and give = me your thoughts.  Thanks for your comments. 
Ken Johnson

=


From: Tracy <rwstracy@gmail.com>
To:<= /span> Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Wednesday, October 24, 2012 12:21 P= M
Subject: [FlyRotary] = Re: flow path in conventional radiator

=0A

On= Oct 24, 2012, at 10:14 AM, Kenneth Johnson <kjohnsondds@yahoo.com> wrote:

> A more effi= cient design would  have intake air entering the bottom anterior of th= e the cowl and to pass through the radiator.  As this air is heated b= y the radiator it rises and should exit the top sides of the cowl.  No= one has done that because of the risk of engine oil on the windshield.
=

I haven't read Paul's book but if this is an example of his suggest= ions, I wouldn't have much confidence in it. 

Two basic rules = of thumb for A/C cooling systems are:

1. Turning high speed air is h= ard to do and loss prone energy wise.

2.  The pressure represe= nted by convection of rising hot air is not significant  and can safel= y be ignored for our purposes. =20

Tracy
--
Homepage: =0A http://www.flyrotary.com/
A= rchive and UnSub:  http://mail.lancai= ronline.net:81/lists/flyrotary/List.html




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