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Thu, 05 May 2011 16:02:56 PDT X-Mailer: YahooMailWebService/0.8.110.299900 References: Date: Thu, 5 May 2011 16:02:56 -0700 (PDT) From: Dwayne Parkinson Reply-To: Dwayne Parkinson Subject: Re: [FlyRotary] Re: Cooling Inlets To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1725103539-1304636576=:90590" --0-1725103539-1304636576=:90590 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable OK, here's my crazy scheme. =A0Use NACA ducts for the inlet and have cowl f= laps for the outlet. =A0Unlike normal fixed NACA ducts, I'm hoping I can ma= ke them work like vents that open and close. =A0I've seen this on at least = two Sonex planes except they use them for cabin air inlets, not cooling. = =A0I don't know if changing the height of the opening in a NACA duct in rel= ation to it's width messes with the aerodynamics, but I'm hoping it doesn't= . =A0Assuming that's the case, my great big hopeful idea is that I can bala= nce the intake and the outlet area so that the cowl flaps and NACA ducts wo= rk in unison to maintain a perfectly balanced air flow through the cooling = system with just enough cooling drag to keep the temps where they need to b= e. =A0 I'm trying to address the idea that I've got to design the intake an= d cooling drag so it handles taxiing on a 95 degree day but then continue t= o pay that drag penalty as I'm cruising along at 10,000 feet in zero degree air.=0A=0ADwayne=0A=0A=0A=0A________________________________=0AFrom: Ed An= derson =0ATo: Rotary motors in aircraft =0ASent: Saturday, April 30, 2011 9:00 AM=0ASubject: [= FlyRotary] Re: Cooling Inlets=0A=0A=0A =0AI agree, Steve.=A0 There is no qu= estion each part of =0Athe cooling=A0system =A0is critical and the total re= sults is no better =0Athan the weakest link.=A0 =0A=A0=0AMost studies I hav= e read indicates that after a certain =0Asize in inlet area (from 25-35% of= core frontal area) - the outlet size becomes =0Athe determining factor and= further increases in intake provide no additional =0Abenefit and can hurt = by increasing cooling drag.=A0 Adding such things as =0Acowl flaps can redu= ce the pressure in the outlet region and promote more airflow =0Aand coolin= g but naturally at the cost of more drag.=A0 But, then at higher =0Aspeeds = with plenty of dynamic pressure, you can retract the cowl flaps and =0Aredu= ce the drag.=0A=A0=0ANACA ducts have been made to work with radiator =0Acor= es=A0- no question about that.=A0 The question is would a different =0Aappr= oach have produced a "better" cooling system.=A0 Again, I think it =0Adepen= ds on your intended operating environment.=A0 =0A=A0=0AFor a high speed cru= ise environment, I would think cooling =0Adrag might be of more importance = than say perhaps a few pounds of additional =0Aweight, on the other hand if= you are flying an already draggy biplane for =0Aexample, cooling drag is p= robably a very small part of your over all drag, but =0Agetting cooling wit= h low airspeed might be the system driver.=0A=A0=0AIts all about compromise= s - space, weight, flow, drag, =0Aetc. - oh, yes! - and cooling of course {= :>)=A0 all matched to your =0Aconstraints and operating environment.=0A=A0= =0AEd=0A=A0=0A=0A=0AFrom: stevei@carey.asn.au =0ASent: Friday, April 29, 20= 11 8:48 PM=0ATo: Rotary motors in aircraft =0ASubject: [FlyRotary] Re: Cool= ing Inlets=0AHi Ed and Dwayne =0A=0AI'm working on my inlet and outlet for = Renesis powered Glasair SIIRG.=0AIt seems whenever we turn our attention to= air, it is not about inlets or =0Aoutlets but pressure differentials and t= he whole system.=0AA great inlet is killed by a lousy outlet, and both made= mute by inadequate =0Adiffusion.=0APerhaps a NACA would work adequately gi= ven a system with good diffusion =0Athat SUCKED well.=0A=0ACheers=0ASteve I= zett=0ANot flying, so maybe completely deluded.=A0=0AContinues to more than= respect Tracy's thoughts and practices.=0A=0A=0AOn 30/04/2011, at 7:26 AM,= Ed Anderson wrote:=0A=0ADwayne=0A>=A0=0A>There is a NACA study on NACA duc= ts which in essence found that while they were excellent for feeding an in= take (an duct with no internal resistance such as a heat exchanger core) s= uch as an engine intake, that their performance suffered relative to other= duct configurations -=A0where you had a radiator core installed.=A0 The = reason appeared to be that the pressure build up before the core hindered t= he airflow into the duct and caused a lot of the air to flow around the op= ening. On the good side, they were relatively low drag ducts.=A0=0A>=A0=0A= >Now that being said, several approaches have been found that seems to off= set the problems.=A0 One that comes to mind is the placement of vortex gen= erators which guide more airflow into the ducts and the other one is the p= lacement of the inlet in a high pressure area.=A0 Folks have used them suc= cessfully for cooling - so long as sufficient airflow can be achieved thro= ugh the duct the core doesn't care what kind of opening is used.=0A>=A0=0A= >Ed=0A>=A0=0A>Edward L. Anderson=0A>Anderson =0A Electronic Enterprises LL= C=0A>305 Reefton Road=0A>Weddington, NC 28104=0A>http://www.andersonee.com= =0A>http://www.eicommander.com=0A>=0A>=0A>=0A>From:=A0Dwayne Parkinson=0A>S= ent:=A0Friday, April 29, 2011 5:05 PM=0A>To:=A0Rotary motors in aircraft=0A= >Subject:=A0[FlyRotary] Re: Cooling Inlets=0A>=0A>=0A>OK, I gotta ask. =A0= Does anyone use NACA ducts for cooling inlets? =A0Why or why not? =A0=0A>= =0A>=0A>=0A>________________________________=0A> From:=A0Tracy =0A>To:=A0Rotary motors in aircraft = =0A>Sent:=A0Fri, April 29, 2011 9:49:00 AM=0A>Subject:=A0[FlyRotary] Re: C= ooling Inlets=0A>=0A>Some questions:=0A>Prior reading seemed to indicate t= hat =0A the oil cooler did ~1/3 of the cooling, implying a 2/1 ratio on ai= r =0A requirements. This setup seems to have a significantly higher percen= tage =0A allocated to oil. Is this a byproduct of heat exchanger differenc= es, or the =0A less efficient heat transfer ability of oil, or....?=0A>=0A= >2nd, assuming =0A similar inlet & diffuser efficiencies, could the inlet = areas mentioned be =0A reduced by roughly 1/3 with reasonable expectation = of cooling a 2 rotor =0A Renesis?=0A>=0A>On the subject of exit area: Does= either heat exchanger have =0A an exit duct? The RV guys with really fast= Lyc powered planes all have some =0A variation of exit ducting to smoothl= y re-accelerate and redirect exit air =0A parallel to & at or above the sl= ipstream. Even the stock RV-8 has a =0A rounded lip at the bottom of the f= irewall (which the really fast guys say is =0A much too small a radius...)= . And there's always the near-mythical P-51 =0A system...=0A>=0A>Thanks,= =0A>Charlie=0A>=0A>The inlets were originally closer =0A to the 2 - 1 area= ratio but many experiments (mostly failures) ended up with =0A the curren= t sizes.=A0 I just don't have it in me to go back and un-do them =0A all.= =A0 Also wish I had tried these inlets with my original oil cooler =0A whi= ch had about 1/3 more core volume and much thicker.=A0=A0 Might have =0A b= een able to do the oil cooling with less CFM airflow. =A0 But, I don't =0A = think there is much penalty for having more than enough (but properly fair= ed) =0A inlet area and throttling the airflow with a cowl flap.=0A>=0A>Yes= , I do think =0A both inlets could be scaled down in area for a 2 rotor.= =0A>=0A>Neither of my =0A heat exchangers have exit ducts.=A0 Just not eno= ugh room to do this in =0A their current locations.=0A>=0A>Tracy=0A>=A0=A0= =0A>=0A>=0A>=0A>On Thu, Apr 28, 2011 at 4:23 PM, Charlie England=A0=A0wrote:=0A>=0A>On 4/28/2011 8:07 AM, Tracy wrote: =0A>>= Finally got around to finishing my cooling inlets. (pictures attached)=A0 = Up until now they were simply round pipes sticking out of the cowl.=A0=A0 = The pipes are still there but they have properly shaped bellmouths on them= .=A0=A0 The shape and contours were derived from a NASA contractor report = (NASA_CR3485) that you can find via Google.=A0 Lots of math & formulas in = it but I just copied the best performing inlet picture of the contour.=A0= =A0 Apparently there is an optimum radius for the inner and outer lip of t= he inlet.=A0=A0 There was no change to the inlet diameters of 5.25" on wat= er cooler and 4.75" on oil cooler.=0A>>>=0A>>>The simple pipes performed a= dequately in level =0A flight at moderate cruise settings even on hot = days but oil temps would =0A quickly hit redline at high power level f= light and in climb.=A0=A0=0A>>>=0A>>>The significant change =0A with t= he new inlet shape is that they appear to capture off-axis air =0A flo= w=A0 (like in climb and swirling flow=A0 induced by prop at high =0A p= ower)=A0 MUCH better than the simple pipes. =A0=A0 First flight =0A te= st was on a 94 deg. F day and I could not get the oil temp above 200 =0A = degrees in a max power climb. =A0=A0 They may have gone higher if =0A = the air temperature remained constant but at 3500 fpm the rapidly =0A = decreasing OAT kept the temps well under redline (210 deg F).=0A>>>=0A>>= >I =0A have an air pressure instrument reading the pressure in front o= f the oil =0A cooler and was amazed at the pressure recovered from the= prop wash.=A0 =0A At 130 MPH the pressure would almost double when th= e throttle was advanced =0A to WOT. =A0 That did not happen nearly as = much with the simple =0A pipes.=A0=A0=A0=0A>>>=0A>>>These inlets =0A = ROCK!=0A>>>=0A>>>Tracy =0A Crook=0A>>>=0A>>>Perfect timing for me; I= need to decide whether to take a loss & sell my (RV-7)=A0 James Lyc style= cowl=A0& replace it with James' rotary cowl, or just modify the existing = cowl.=0A>>=0A>>Some =0A questions:=0A>>Prior reading seemed to indicate = that the oil cooler did ~1/3 =0A of the cooling, implying a 2/1 ratio on= air requirements. This setup seems =0A to have a significantly higher p= ercentage allocated to oil. Is this a =0A byproduct of heat exchanger di= fferences, or the less efficient heat transfer =0A ability of oil, or...= .?=0A>>=0A>>2nd, assuming similar inlet & diffuser =0A efficiencies, cou= ld the inlet areas mentioned be reduced by roughly 1/3 with =0A reasonab= le expectation of cooling a 2 rotor Renesis?=0A>>=0A>>On the subject =0A = of exit area: Does either heat exchanger have an exit duct? The RV guys wi= th =0A really fast Lyc powered planes all have some variation of exit du= cting to =0A smoothly re-accelerate and redirect exit air parallel to & = at or above =0A the slipstream. Even the stock RV-8 has a rounded lip at= the bottom of the =0A firewall (which the really fast guys say is much = too small a radius...). And =0A there's always the near-mythical P-51 = =0A system...=0A>>=0A>>Thanks,=0A>>=0A>>Charlie=0A>>=0A>>=0A>>=0A>=0A>= =0A=0A________________________________=0A The contents of this email are co= nfidential =0Aand intended only for the named recipients of this e-mail. If= you have received =0Athis e-mail in error, you are hereby notified that an= y use, reproduction, =0Adisclosure or distribution or the information conta= ined in this e-mail is =0Aprohibited. Please notify the sender immediately = and then delete/destroy the =0Ae-mail and any printed copies. All liability= for viruses is excluded to the =0Afullest extent of the law. --0-1725103539-1304636576=:90590 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
OK, here's my crazy scheme.=  Use NACA ducts for the inlet and have cowl flaps for the outlet. &nb= sp;Unlike normal fixed NACA ducts, I'm hoping I can make them work like ven= ts that open and close.  I've seen this on at least two Sonex planes e= xcept they use them for cabin air inlets, not cooling.  I don't know i= f changing the height of the opening in a NACA duct in relation to it's wid= th messes with the aerodynamics, but I'm hoping it doesn't.  Assuming = that's the case, my great big hopeful idea is that I can balance the intake= and the outlet area so that the cowl flaps and NACA ducts work in unison t= o maintain a perfectly balanced air flow through the cooling system with ju= st enough cooling drag to keep the temps where they need to be.   I'm = trying to address the idea that I've got to design the intake and cooling drag so it handles taxiing on a 95 degree day but then continue to= pay that drag penalty as I'm cruising along at 10,000 feet in zero degree = air.

Dwayne


From: Ed Anderson <eanderson@carolina.= rr.com>
To: Rotary m= otors in aircraft <flyrotary@lancaironline.net>
Sent: Saturday, April 30, 2011 9:00 AM
Subject: [FlyRotary] Re: Coo= ling Inlets

=0A
=0A=0A=0A =0A= =0A=0A=0A =0A
I agree, Steve.  There is no qu= estion each part of =0Athe cooling system  is critical and the to= tal results is no better =0Athan the weakest link. 
=0A 
=0A
Mos= t studies I have read indicates that after a certain =0Asize in inlet area = (from 25-35% of core frontal area) - the outlet size becomes =0Athe determi= ning factor and further increases in intake provide no additional =0Abenefi= t and can hurt by increasing cooling drag.  Adding such things as =0Ac= owl flaps can reduce the pressure in the outlet region and promote more air= flow =0Aand cooling but naturally at the cost of more drag.  But, then= at higher =0Aspeeds with plenty of dynamic pressure, you can retract the c= owl flaps and =0Areduce the drag.
=0A
=  
=0A
NACA ducts have been made t= o work with radiator =0Acores - no question about that.  The ques= tion is would a different =0Aapproach have produced a "better" cooling syst= em.  Again, I think it =0Adepends on your intended operating environme= nt. 
=0A
 
=0A<= div>For a high speed cruise environment, I would think= cooling =0Adrag might be of more importance than say perhaps a few pounds = of additional =0Aweight, on the other hand if you are flying an already dra= ggy biplane for =0Aexample, cooling drag is probably a very small part of y= our over all drag, but =0Agetting cooling with low airspeed might be the sy= stem driver.
=0A
 
= =0A
Its all about compromises - space, weight, flo= w, drag, =0Aetc. - oh, yes! - and cooling of course {:>)  all match= ed to your =0Aconstraints and operating environment.
=0A
 
=0A
Ed
=0A
 
=0A
=0A

=0A
=0A= =0A
Sent: Fr= iday, April 29, 2011 8:48 PM
=0A=0ASubject: [FlyRotary] Re: Cooling Inlets
=0A
Hi Ed and Dwayne =0A

=0A
I'm working on my inlet = and outlet for Renesis powered Glasair SIIRG.
=0A
It seems wheneve= r we turn our attention to air, it is not about inlets or =0Aoutlets but pr= essure differentials and the whole system.
=0A
A great inlet is ki= lled by a lousy outlet, and both made mute by inadequate =0Adiffusion.=0A
Perhaps a NACA would work adequately given a system with good diff= usion =0Athat SUCKED well.
=0A

=0A
Cheers
=0ASteve Izett
=0A
Not flying, so maybe completely deluded. <= /div>=0A
Continues to more than respect Tracy's thoughts and practices.=
=0A

=0A
=0A
On 30/04/2011, at 7:26 AM, Ed Anderson wr= ote:

=0A=0A
=0A
Dwayne
=0A
 
=0A
There is a NACA study on NACA ducts =0A which in essence f= ound that while they were excellent for feeding an intake =0A (an duct wit= h no internal resistance such as a heat exchanger core) such as an =0A eng= ine intake, that their performance suffered relative to other duct =0A con= figurations - where you had a radiator core installed.  The =0A = reason appeared to be that the pressure build up before the core hindered t= he =0A airflow into the duct and caused a lot of the air to flow around th= e opening. =0A On the good side, they were relatively low drag ducts. = ;
=0A
&= nbsp;
=0A
Now that be= ing said, several =0A approaches have been found that seems to offset the = problems.  One that =0A comes to mind is the placement of vortex gene= rators which guide more airflow =0A into the ducts and the other one is th= e placement of the inlet in a high =0A pressure area.  Folks have use= d them successfully for cooling - so long =0A as sufficient airflow can be= achieved through the duct the core doesn't care =0A what kind of opening = is used.
=0A
<= /font> 
=0A
Ed
=0A
&nbs= p;
=0A
Edward L. Ande= rson
Anderson =0A Electronic Enterprises LLC
305 Reefton Road
Wed= dington, NC 28104
http://www.andersonee.com
http://www.eicommander.co= m
=0A
=0A
=0A
=0A =0A
Sent: Friday, April 29, 2011 = 5:05 PM
=0A =0A
Subject: [FlyRotary] Re: Cool= ing =0A Inlets
=0A

= =0A
=0A
OK, I gotta ask.  Does anyone use= NACA ducts for =0A cooling inlets?  Why or why not?  
=0A =

=0A
=0A
=0A From: Tracy <rwstracy@gm= ail.com>
To: Rotary motors in = aircraft <flyrotary@la= ncaironline.net>
Sent: Fri, Ap= ril 29, 2011 9:49:00 =0A AM
Subjec= t: [FlyRotary] Re: Cooling =0A Inlets

Some questions:
Prior= reading seemed to indicate that =0A the oil cooler did ~1/3 of the coolin= g, implying a 2/1 ratio on air =0A requirements. This setup seems to have = a significantly higher percentage =0A allocated to oil. Is this a byproduc= t of heat exchanger differences, or the =0A less efficient heat transfer a= bility of oil, or....?

2nd, assuming =0A similar inlet & diffus= er efficiencies, could the inlet areas mentioned be =0A reduced by roughly= 1/3 with reasonable expectation of cooling a 2 rotor =0A Renesis?

= On the subject of exit area: Does either heat exchanger have =0A an exit d= uct? The RV guys with really fast Lyc powered planes all have some =0A var= iation of exit ducting to smoothly re-accelerate and redirect exit air =0A = parallel to & at or above the slipstream. Even the stock RV-8 has a = =0A rounded lip at the bottom of the firewall (which the really fast guys = say is =0A much too small a radius...). And there's always the near-mythic= al P-51 =0A system...

Thanks,
Charlie

The inlets were ori= ginally closer =0A to the 2 - 1 area ratio but many experiments (mostly fa= ilures) ended up with =0A the current sizes.  I just don't have it in= me to go back and un-do them =0A all.  Also wish I had tried these i= nlets with my original oil cooler =0A which had about 1/3 more core volume= and much thicker.   Might have =0A been able to do the oil cool= ing with less CFM airflow.   But, I don't =0A think there is much pen= alty for having more than enough (but properly faired) =0A inlet area and = throttling the airflow with a cowl flap.

Yes, I do think =0A both i= nlets could be scaled down in area for a 2 rotor.

Neither of my =0A = heat exchangers have exit ducts.  Just not enough room to do this in = =0A their current locations.

Tracy
  


=0A
On Thu, Apr 28, 2011 at 4:23 PM,= =0A Charlie England&nbs= p;<ceengland@bellsouth.net> wrote:
=0A
=0A
=0A On 4/28/2011 8:07 AM, Trac= y wrote: =0A
Finally got around to finishing my cooling inle= ts. (pictures =0A attached)  Up until now they were simply round = pipes sticking out of =0A the cowl.   The pipes are still th= ere but they have properly =0A shaped bellmouths on them.   = The shape and contours were derived =0A from a NASA contractor report = (NASA_CR3485) that you can find via =0A Google.  Lots of math &am= p; formulas in it but I just copied the best =0A performing inlet pict= ure of the contour.   Apparently there is =0A an optimum rad= ius for the inner and outer lip of the inlet.   =0A There wa= s no change to the inlet diameters of 5.25" on water cooler and =0A 4.= 75" on oil cooler.

The simple pipes performed adequately in level = =0A flight at moderate cruise settings even on hot days but oil temps = would =0A quickly hit redline at high power level flight and in climb.=   
The significant change =0A with the new inlet shape is that they app= ear to capture off-axis air =0A flow  (like in climb and swirling= flow  induced by prop at high =0A power)  MUCH better than = the simple pipes.    First flight =0A test was on a 94 deg. = F day and I could not get the oil temp above 200 =0A degrees in a max = power climb.    They may have gone higher if =0A the air tem= perature remained constant but at 3500 fpm the rapidly =0A decreasing = OAT kept the temps well under redline (210 deg F).

I =0A have a= n air pressure instrument reading the pressure in front of the oil =0A = cooler and was amazed at the pressure recovered from the prop wash.  = =0A At 130 MPH the pressure would almost double when the throttle was = advanced =0A to WOT.   That did not happen nearly as much with th= e simple =0A pipes.   

These inlets =0A ROCK!

Tracy = =0A Crook

Perfect timing for me; I need = to decide whether to =0A take a loss & sell my (RV-7)  James Ly= c style cowl = & replace =0A it with James' rotary cowl, or ju= st modify the existing cowl.

Some =0A questions:
Prior reading= seemed to indicate that the oil cooler did ~1/3 =0A of the cooling, imp= lying a 2/1 ratio on air requirements. This setup seems =0A to have a si= gnificantly higher percentage allocated to oil. Is this a =0A byproduct = of heat exchanger differences, or the less efficient heat transfer =0A a= bility of oil, or....?

2nd, assuming similar inlet & diffuser = =0A efficiencies, could the inlet areas mentioned be reduced by roughly = 1/3 with =0A reasonable expectation of cooling a 2 rotor Renesis?
On the subject =0A of exit area: Does either heat exchanger have an exi= t duct? The RV guys with =0A really fast Lyc powered planes all have som= e variation of exit ducting to =0A smoothly re-accelerate and redirect e= xit air parallel to & at or above =0A the slipstream. Even the stock= RV-8 has a rounded lip at the bottom of the =0A firewall (which the rea= lly fast guys say is much too small a radius...). And =0A there's always= the near-mythical P-51 =0A system...

Thanks,

Charlie
<= br>

=0A
=0A


=0A
=0AThe co= ntents of this email are confidential =0Aand intended only for the named re= cipients of this e-mail. If you have received =0Athis e-mail in error, you = are hereby notified that any use, reproduction, =0Adisclosure or distributi= on or the information contained in this e-mail is =0Aprohibited. Please not= ify the sender immediately and then delete/destroy the =0Ae-mail and any pr= inted copies. All liability for viruses is excluded to the =0Afullest exten= t of the law.
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