X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-qy0-f174.google.com ([209.85.221.174] verified) by logan.com (CommuniGate Pro SMTP 5.3c4) with ESMTP id 4036507 for flyrotary@lancaironline.net; Wed, 23 Dec 2009 08:35:09 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.221.174; envelope-from=rwstracy@gmail.com Received: by qyk4 with SMTP id 4so3051102qyk.7 for ; Wed, 23 Dec 2009 05:34:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to :content-type; bh=4SAXUbnhDYU4v2OUww7OG+fLIceXnu3kD/MHKu+KK7U=; b=PLYML8QGf/R4awYFMxkZgL5UYCiqRco3vVV48fNiXvn/hCNLsEVE/ETSknMq1t6Efq UgZajZeieeXopDE6EwXm5N48zQ+N9U6EH5d/+17PxWvM9nchETSeU7BUBOTryDMftko6 RSYSNxU53PLg7vKiZE0pC3/fDmwLIuh5mFsJ0= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=OwbtWiaS++ob94aXOAGOkbEL1EDSpv6aHzwoW9UN7M6zRRUCyGr0IV2zCCya+7ntPu EVzJFLrpwa/k8IhutU2uw8FofOi4p1zHpxRQk+mPWM74LkEK1tdnAav0H8gf2c04c7zZ 8133HpLg0l9woqGv4f/MHDsGw8xlyTFs0ICPg= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.78.17 with SMTP id i17mr5197484qak.359.1261575273107; Wed, 23 Dec 2009 05:34:33 -0800 (PST) In-Reply-To: References: Date: Wed, 23 Dec 2009 08:34:32 -0500 X-Google-Sender-Auth: 2b6d8868682e5cc3 Message-ID: <1b4b137c0912230534q465fccd9l462859717b4b378f@mail.gmail.com> Subject: Re: [FlyRotary] Re: Mereidth effect: [FlyRotary] Re: Air Flow Question From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=00c09f8a4f1802d15a047b656292 --00c09f8a4f1802d15a047b656292 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Scott, Sounds like you should have plenty of cooling even if your diffusers are halfway effective. My 5" round inlet for the radiator looks ridiculously small compared to yours but so far it is cooling the 20B OK. Your oil cooler diffuser looks pretty nice. Only suggestion I would have is that it should be pinched a little tighter at the aft end. Mine had the same shortcomming but I remedied that with some roof ridge vent material stuck i= n at the rear 20%. 200 HP is a pretty conservative target for that turbo setup. Should get that easily. The side exit for the oil cooler is one I considered before changing my cooler. That's a much lower pressure than the usual bottom exit area. Onl= y problem is making it easy to remove the cowl for inspection. I couldn't come up with a good way to do that and still get a good seal to the side exit. Frequent inspections during the first 40 or so hours are especially important. Because I'm basically lazy, I imposed an 'easy to inspect' requirement on my installation. If it's not, I find excuses not to do them. Tracy On Tue, Dec 22, 2009 at 9:49 PM, wrote: > Yes; > Thanks Ed. I went out to the garage and looked at my chin scoop radiator. > It fails to conform to the shape reccomended in the article. :( > But it does cool well in ground testing so far. I leaned heavily toward > pressure recovery from the supposed bow wake effect, and can't verify if = I > get any diffuser effect because of the slope of the cooler core. I know t= his > is not optimal, but I wanted greater core area and less core depth so air > would pass thru the core with a lower differential pressure. > Here is a link to my EAA Capter's site, direct to my pictures: > http://gallery.eaa326.org/members/semery/ > Constructive comments are always welcome. > I did try to keep external drag to a minimum, and have an Inlet area of > about 52 In Sq, over a Core face area of 306 In Sq. > for a intlet / core ratio 17 % which seems small for the core. > The Horse Power target is 200, so the 1.8 cubic inch core volume to HP = =3D > 360 cubic inches. My core is 2" thick for 612 cubic inches. So I > theoretically only require 59% of my existing core volume. 180 square inc= hes > of 2 inch thick core. > My inlet opening =3D 29% of that, so I'm close to optimum on inlet openin= g > area. As I continue to test, and eventually fly, I could change to a smal= ler > cooler, which could set it more 'normal' to the air flow, while also movi= ng > it aft allowing a longer diffuser. > The side mounted oil cooler was not a matter of choices. The Mazda cooler > comes in one size, so does the cowl cheek opening. I just measured my > diffuser inlet, 24.8 In Sq. The cooler face: 87.75 In Sq. Ratio =3D 28%. = I > think that's pretty good considering the airflow must turn 90 degrees to > pass thru the core, then get sucked out thru surface louvers on the cowl > side. > Here's hoping for the best, and trying again if it doesn't work. > > > > > -----Original Message----- > From: Thomas Mann > To: Rotary motors in aircraft > Sent: Mon, Dec 21, 2009 6:01 pm > Subject: [FlyRotary] Re: Mereidth effect: [FlyRotary] Re: Air Flow Questi= on > > Thanks for the links Ed. > It looks like I have some reading to do! > > > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] > *On Behalf Of *Ed Anderson > *Sent:* Monday, December 21, 2009 7:19 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Mereidth effect: [FlyRotary] Re: Air Flow Question > > > Thomas, Here is probably the best, most understandable (without a lot of > math) on the cooling challenge that I have come across. You might want = to > check it out. Here is one of the statements you will find in this short > article > > *It has been shown that the diffuser efficiency is key in the reduction o= f > the overall radiator drag. It is the most critical part, and unfortunatel= y > the most frequently botched by homebuilders.*** > > http://contrails.free.fr/engine_aerodyn_radia_en.php > > Also note his comment about how to control airflow once your intake is > 30-50% of your core area =96 may surprise you. > > > http://contrails.free.fr/tunnel_en.php > > > Here is a summary by Meredith on the effect. There is still some debate > about whether the P-51 cooling system actually resulted in a net thrust = =96 > but, most agree whether it did produce significant thrust or not the cool= ing > drag was probably close to an optimum minimum. > > http://contrails.free.fr/refroid_meredith_en.php > > You are right, there is always trade offs. You can certainly put an oil > cooler in front of your radiator =96 in effect you are just making a thic= k > radiator as far as airflow is concerned. Obviously you will have hotter = air > flow through the part of your radiator behind the oil cooler so its cooli= ng > effectiveness will be reduced. Also, you may find that a lot of the air = in > their common duct may want to go through the other part of the radiator c= ore > =96 due to its less air resistance. > Placing them side by side (or top bottom) is another approach. However, = it > is my opinion that unless your oil cooler and radiator core have similar = air > flow characteristics or great care is taken in designing your ducts to ea= ch, > that air will take the route of least resistance. So one core could end= up > =93bleeding=92=94 cooling air from the other. Similarly, the exit pressu= re of one > (generally the one with the least air resistance) will be higher than the > one with less resistance. So this can cause airflow problems under the co= wl > as well. > Its my opinion that keeping your oil and coolant cores separate (if > possible and there are always space constraints in our vehicles) and also > keeping their air flow separate is generally the best course of action to > get the best cooling. But, compromises are frequently necessary, in whic= h > case you simply have to try and figure out the possible interaction and > effects. > > Ed > > Ed Anderson > Rv-6A N494BW Rotary Powered > Matthews, NC > eanderson@carolina.rr.com > http://www.andersonee.com > http://www.dmack.net/mazda/index.html > http://www.flyrotary.com/ > http://members.cox.net/rogersda/rotary/configs.htm#N494BW > http://www.rotaryaviation.com/Rotorhead%20Truth.htm > ------------------------------ > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] > *On Behalf Of *Thomas Mann > *Sent:* Monday, December 21, 2009 6:17 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Air Flow Question > > =93Stick with this group, we=92ve all been there and have conquered the > cooling beast =96 well, at least tamed it a bit. > > Ed=94 > > > That is the plan Ed. > I=92m trying to figure out how much radiator I can fit into my configurat= ion. > I=92m running the numbers and drafting it out in AutoCAD. > > I=92m hoping that I can cash in on the Meredith Effect in my design. I=92= m > planning on an adjustable exhaust opening much like the P-51s had. I=92m = not > sure if I need it or not but it=92s easier to not use it vs. add it later= . > > Question: If I use a separate oil cooler, can I place it in front of the > radiator? > I=92ve seen some installations like this but it seems to me that there is= a > cost involved. > > T Mann > > > __________ Information from ESET NOD32 Antivirus, version of virus > signature database 3267 (20080714) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > --00c09f8a4f1802d15a047b656292 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Scott,
Sounds like you should have plenty of cooling even if your diffus= ers are halfway effective.=A0 My 5" round inlet for the radiator looks= ridiculously small compared to yours but so far it is cooling the 20B OK.= =A0 Your oil cooler diffuser looks pretty nice.=A0 Only suggestion I would = have is that it should be pinched a little tighter at the aft end.=A0 Mine = had the same shortcomming but I remedied that with some roof ridge vent mat= erial stuck in at the rear 20%. =A0 200 HP is a pretty conservative target = for that turbo setup.=A0 Should get that easily.

=A0 The side exit for the oil cooler is one=A0 I considered before chan= ging my cooler.=A0 That's a much lower pressure than the usual bottom e= xit area.=A0 Only problem is making it easy to remove the cowl for inspecti= on.=A0=A0 I couldn't come up with a good way to do that and still get a= good seal to the side exit. =A0 Frequent inspections during the first 40 o= r so hours are especially important.=A0 Because I'm basically lazy, I i= mposed an 'easy to inspect' requirement on my installation.=A0=A0 I= f it's not, I find excuses not to do them.

Tracy

On Tue, Dec 22, 2009 at 9:49 PM= , <shipchief@aol= .com> wrote:
Yes;
Thanks Ed. I went out to the garage and looked at my chin scoop radiat= or.
It fails to conform to the shape reccomended in the article. :(
But it does cool well in ground testing so far. I leaned heavily towar= d pressure recovery from the supposed bow wake effect, and can't verify= if I get any diffuser effect because of the slope of the cooler core. I kn= ow this is not optimal, but I wanted greater core area and less core depth = so air would pass thru the core with a lower differential pressure.
Here is a link to my EAA Capter's site, direct to my pictures:=A0 = htt= p://gallery.eaa326.org/members/semery/
Constructive comments are always welcome.
I did try to keep external drag to a minimum, and have an Inlet area o= f about 52 In Sq, over a Core face area of 306 In Sq.
for a=A0intlet /=A0core=A0ratio 17 % which seems small for the core. <= /div>
The Horse Power target is 200, so the 1.8 cubic inch core volume to HP= =3D 360 cubic inches. My core is 2" thick for 612 cubic inches. So I = theoretically only require 59% of my existing core volume. 180 square inche= s of 2 inch thick core.
My inlet opening =3D 29% of that, so I'm close to optimum on inlet= opening area. As I continue to test, and eventually fly, I could change to= a smaller cooler, which could set it more 'normal' to the air flow= , while also moving it aft allowing a longer diffuser.
The side mounted oil cooler was not a matter of choices. The Mazda coo= ler comes in one size, so does the cowl cheek opening. I just measured my d= iffuser inlet, 24.8 In Sq. The cooler face: 87.75 In Sq. Ratio =3D 28%. I t= hink that's pretty good considering the airflow must turn 90 degrees to= pass thru the core, then get sucked out thru surface louvers on the cowl s= ide.
Here's hoping for the best, and trying again if it doesn't work.



-----Original Message-----
From: Thomas Mann <tmann@n200lz.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Mon, Dec 21, 2009 6:01 pm
Subject: [FlyRotary] Re: Mereidth effect: [FlyRotary] Re: Air Flow Question=

Thanks for the links Ed.
It looks like I have some reading to do!
=A0
=A0
From: Rotary motors in aircraft [mailto:flyrotary@lanc= aironline.net] On Behalf Of Ed Anderson
Sent: Monday, December 21, 2009 7:19 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Mereidth effect: [FlyRotary] Re: Air Flow Quest= ion
=A0
=A0<= /span>
Thom= as, Here is probably the best, most understandable (without a lot of math) = on the cooling challenge that I have come across.=A0=A0 You might want to c= heck it out.=A0 =A0Here is one of the statements you will find in this shor= t article
=A0<= /span>
It has been shown that the diffuser efficiency = is key in the reduction of the overall radiator drag. It is the most critic= al part, and unfortunately the most frequently botched by homebuilders.=
=A0<= /span>
http://contrails.free.fr/engine_aerodyn_radia_en.php
=A0<= /span>
Also= note his comment about how to control airflow once your intake is 30-50% o= f your core area =96 may surprise you.
=A0<= /span>
=A0<= /span>
http://con= trails.free.fr/tunnel_en.php
=A0<= /span>
=A0<= /span>
Here= is a summary by Meredith on the effect.=A0 There is still some debate abou= t whether the P-51 cooling system actually resulted in a net thrust =96 but= , most agree whether it did produce significant thrust or not the cooling d= rag was probably close to an optimum minimum.=A0
=A0<= /span>
= http://contrails.free.fr/refroid_meredith_en.php
=A0<= /span>
You are right, there is = always trade offs.=A0 You can certainly put an oil cooler in front of your = radiator =96 in effect you are just making a thick radiator as far as airfl= ow is concerned.=A0 Obviously you will have hotter air flow through the par= t of your radiator behind the oil cooler so its cooling effectiveness will = be reduced.=A0 Also, you may find that a lot of the air in their common duc= t may want to go through the other part of the radiator core =96 due to its= less air resistance.
Placing them side by sid= e (or top bottom) is another approach.=A0 However, it is my opinion that un= less your oil cooler and radiator core have similar air flow characteristic= s or great care is taken in designing your ducts to each, that air will tak= e the route of least resistance.=A0 So one =A0core could end up =93bleeding= =92=94 cooling air from the other.=A0 Similarly, the exit pressure of one (= generally the one with the least air resistance) will be higher than the on= e with less resistance. So this can cause airflow problems under the cowl a= s well.
Its my opinion that keep= ing=A0 your oil and coolant cores separate (if possible and there are alway= s space constraints in our vehicles) and also keeping their air flow separa= te is generally the best course of action to get the best cooling.=A0 But, = compromises are frequently necessary, in which case you simply have to try = and figure out the possible interaction and effects.
=A0
Ed
From: Rotary motors in aircraft [mailto:flyrotary@lanc= aironline.net] On Behalf Of Thomas Mann
Sent: Monday, December 21, 2009 6:17 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Air Flow Question
=A0
=93Stick with = this group, we=92ve all been there and have conquered the cooling beast =96= well, at least tamed it a bit.
=A0<= /span>
Ed=94
=A0
=A0
That is t= he plan Ed.
I=92m try= ing to figure out how much radiator I can fit into my configuration. I=92m = running the numbers and drafting it out in AutoCAD.
=A0
I=92m hop= ing that I can cash in on the Meredith Effect in my design. I=92m planning = on an adjustable exhaust opening much like the P-51s had. I=92m not sure if= I need it or not but it=92s easier to not use it vs. add it later.<= /div>
=A0
Question:= If I use a separate oil cooler, can I place it in front of the radiator? <= /span>
I=92ve se= en some installations like this but it seems to me that there is a cost inv= olved.
=A0
T Mann


__________ Information from ESET NOD32 Antivirus, version of virus signatur= e database 3267 (20080714) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com<= /div>

--00c09f8a4f1802d15a047b656292--