X-CGP-ClamAV-Result: CLEAN X-VirusScanner: Niversoft's CGPClamav Helper v1.23.0 (ClamAV engine v0.103.0) From: " eanderson@carolina.rr.com" Received: from [47.43.26.133] (HELO p-impout002.msg.pkvw.co.charter.net) by logan.com (CommuniGate Pro SMTP 6.2.14) with ESMTPS id 1264849 for flyrotary@lancaironline.net; Mon, 01 Mar 2021 10:41:14 -0500 Received-SPF: pass receiver=logan.com; client-ip=47.43.26.133; envelope-from=eanderson@carolina.rr.com Received: from [192.168.1.7] ([66.26.208.242]) by cmsmtp with ESMTP id GkfIl6hGgOzbyGkfIlLwGS; Mon, 01 Mar 2021 15:40:56 +0000 X-Authority-Analysis: v=2.3 cv=G/Fi7Os5 c=1 sm=1 tr=0 a=hG3epedDSl5lteqJAkiezQ==:117 a=hG3epedDSl5lteqJAkiezQ==:17 a=Ia-xEzejAAAA:8 a=o1OHuDzbAAAA:8 a=7g1VtSJxAAAA:8 a=_6GpL_ENAAAA:8 a=JqZ3Oo0-iivYthLslYQA:9 a=QEXdDO2ut3YA:10 a=Qa1je4BO31QA:10 a=gvSQh4r-fQ0A:10 a=4PR2P7QzAAAA:8 a=02UbMwsk65-2p0hX4nIA:9 a=F81bKShV8z73vuyz:21 a=frz4AuCg-hUA:10 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=5YQ6H4ZxyGn-KoBYtt8s:22 a=grOzbf7U_OpcSX4AJOnl:22 a=4dqwQCo7Po2mVW515mGf:22 To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: N214FL RV-4 First Flight Date: Mon, 01 Mar 2021 15:40:56 +0000 Message-Id: In-Reply-To: References: Reply-To: eanderson@carolina.rr.com User-Agent: eM_Client/8.1.1054.0 Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="------=_MBD341C9FA-6728-4946-B476-5410BEA8764E" X-CMAE-Envelope: MS4wfApUW/SNn2M9GeU6KPKzcyFWKRi78Mo0rF1WZ/zFCdYpF7YeX6D1QMDzKE/ZoPF/uz6Tg+x8pnitOn6wFHxXUAefkM0kh4FfRfO4/W/uC6XInKVl0bzJ 3Ms0+lQIshbOcGahgxtaUKl6FNwFN2A5XfHZplbOTU7K3hUPrcpFa/wY5mqOaRqvktjLchmT6NL+nA== --------=_MBD341C9FA-6728-4946-B476-5410BEA8764E Content-Type: text/plain; format=flowed; charset=utf-8 Content-Transfer-Encoding: quoted-printable Cooling is a fascinating and complex challenge not helped by urban=20 legens and myths. I recall many years ago of having a discussion with old man Lou Ross=20 (maker of the first Rotary PSRU widely used) about coolant temperature. His view was (as shown by his and others' experiments) that the slower=20 coolant flowed through the radiator then greater the delta T of the=20 coolant - therefore more heat was removed from slower flowing coolant. =20 While I agreed with that data point, I tried to point out the objective= =20 was to get heat removed from the engine and that greater coolant flow=20 (up to a point) would result in more heat removal even though the delta=20 T of the coolant through the radiator would decrease. We "discussed"=20 this matter for some time. I finally made the comment that if slow=20 coolant flow cooled better, then theoretically stopped coolant flow=20 should cool best. Lou paused - then hung up on me and we never talked=20 again. Complicating the situation even more was when some earlier racers indeed=20 tried to improve cooling by increasing coolant flow rate by running=20 faster turning water pumps. When in a number of cases this resulted in=20 poorer cooling, it seemed to confirm the theory that slower flow was=20 best. Of course, in many cases the faster turning water pump produced=20 flow cavitation resulting is less rather than more coolant flow and an=20 over-heated engine lending credence to the slower flow was better=20 theory. So one must keep in mind we are talking about a cooling system with a=20 number of components each which needs to be optimized as part of the=20 total system with the objective of removing the right amount of heat=20 from the engine given the operational environment. The cooling=20 environment of Southern Texas may be different than in Northern Alaska. Ed ------ Original Message ------ From: "Sboese sboese@uwyo.edu" To: "Rotary motors in aircraft" Sent: 2/28/2021 3:43:54 PM Subject: [FlyRotary] Re: N214FL RV-4 First Flight >Finn, > >Just ignore the following message if the contents are obvious: > >A higher flow rate of coolant through the system will result in a=20 >smaller delta T of the coolant. > >The air doesn=E2=80=99t know or care about the coolant flow rate. It is j= ust=20 >removing heat from the exchanger regardless of how that heat got there.=20 > The air flow was sufficient to keep temps under control for the=20 >conditions of that flight. With the same air flow rate and power=20 >setting, an increase in OAT will result in an increase in the exchanger=20 >(coolant) temp since the amount of heat removed is dependent on the air=20 >flow rate and the air delta T. Increasing the power in addition to the=20 >OAT with the same air flow rate will increase the coolant temps even=20 >more. > >This all assumes that the overall efficiency of the heat exchanger is=20 >affected minimally by the coolant flow rate. The efficiency of the=20 >exchanger should increase somewhat with an increase in coolant flow=20 >rate but it is difficult to predict by how much. > >There is something to be said for changing only one thing at a time,=20 >though. > >Steve Boese > >>On Feb 28, 2021, at 12:47 PM, Finn Lassen finn.lassen@verizon.net=20 >> wrote: >> >>=EF=BB=BF >>=E2=97=86 This message was sent from a non-UWYO address. Please exercise= =20 >>caution when clicking links or opening attachments from external=20 >>sources. >> >> >>Here's pictures of the small in- and outlets. (looking into 5/8" and=20 >>3/4 OD tubes). >> >>Finn >> >>On 2/27/2021 11:29 PM, Finn Lassen finn.lassen@verizon.net=20 >> wrote: >>>Yep, inlet/outlets on rads are very, very restrictive. 7/64x1/2"=20 >>>(0.05 sqin or 1/4" diameter hole equivalent)) at best. I was aware of=20 >>>it when I JB-welded 5/8" and 3/4" over existing tubes and "just=20 >>>wanted to see how it would work" and then forgot about it. >>> >>>Drilling holes in tank end plates I also found a small tube inside=20 >>>one tank and baffles in both tanks. Now removed. >>> >>>As for airflow, when I get new elbows welded onto the rads I'll=20 >>>collect new data. I think the large delta is due to the very slow=20 >>>coolant flow -- stays in rads way too long (and thus not circulating=20 >>>through the engine fast enough). >>> >>>Finn >>> >>>On 2/27/2021 9:32 PM, Steven W. Boese SBoese@uwyo.edu=20 >>> wrote: >>>>Finn, >>>> >>>>If the "WTeng" sensor location is somewhere in the engine block and=20 >>>>not at the coolant outlet and the "WTout" sensor is in the coolant=20 >>>>exiting the engine, then the coolant flow rate through the system=20 >>>>may need to be increased by enlarging the radiator connections.=C3=AF= =C2=BF=C2=BD=20 >>>>Typically, it seems that at normal operating temps, the delta-T=20 >>>>across the engine and across the radiators is about 15 deg F. >>>> >>>>It also would appear that the mass air flow through the radiators=20 >>>>may need to be increased since the air delta T is quite large and=20 >>>>the temp of the air exiting the radiators is close to temp of the=20 >>>>coolant exiting the radiators.=C3=AF=C2=BF=C2=BD If your OAT were incre= ased to 100=20 >>>>deg F, you could see "WTout" of ~250 deg F with the setup as it is=20 >>>>now. >>>> >>>>The attached plots show the effect of changing only the air inlet=20 >>>>and outlet areas of my system which has ~0.9" id plumbing to the=20 >>>>single radiator.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD >>>> >>>>FWIW >>>> >>>>Steve Boese >>>> >>>> >>>> >>>>-- >>>>Homepage: http://www.flyrotary.com/ >>>>Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/L= ist.html >>> >>> >>> >>> >>>------------------------------------------------------------------------= -------- >>>Avast logo >>> >>>This email has been checked for viruses by Avast antivirus software. >>>www.avast.com >>> >>> >>><#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >> >> >> >> >>-- >>Homepage: http://www.flyrotary.com/ >>Archive and UnSub: =20 >>http://mail.lancaironline.net:81/lists/flyrotary/List.html --------=_MBD341C9FA-6728-4946-B476-5410BEA8764E Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Cooling is a fascinat= ing and complex challenge not helped by urban legens and myths.
<= br />
I recall many years ago of having a discussion with old man = Lou Ross (maker of the first Rotary PSRU widely used) about coolant temper= ature.

His view was (as shown by his and others' = experiments) that the slower coolant flowed through the radiator then grea= ter the delta T of the coolant - therefore more heat was removed from slowe= r flowing coolant.=C2=A0 =C2=A0 While I agreed with that data point, I trie= d to point out the objective was to get heat removed from the engine and th= at greater coolant flow (up to a point) would result in more heat removal e= ven though the delta T of the coolant through the radiator would decrease.= =C2=A0 We "discussed" this matter for some time.=C2=A0 I finally made the c= omment that if slow coolant flow cooled better, then theoretically stopped= coolant flow should cool best.=C2=A0 Lou paused - then hung up on me and we = never talked again.

Complicating the situation= even more was when some earlier racers indeed tried to improve cooling by i= ncreasing coolant flow rate by running faster turning water pumps.=C2=A0 Wh= en in a number of cases this resulted in poorer cooling, it seemed to confi= rm the theory that slower flow was best.=C2=A0 Of course, in many cases the = faster turning water pump produced flow cavitation resulting is less rathe= r than more coolant flow and an over-heated engine lending credence to the= slower flow was better theory.=C2=A0=C2=A0

So on= e must keep in mind we are talking about a cooling system with a number of= components each which needs to be optimized as part of the total system wit= h the objective of removing the right amount of heat from the engine given= the operational environment.=C2=A0 The cooling environment of Southern Texa= s may be different than in Northern Alaska.=C2=A0=C2=A0

Ed

------ Original Message ------
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: 2/28/2021 3:43:54 PM
Subject: [FlyRotary] Re: N214FL RV-4 First Flight

Finn,

Just ignore the following message if the content= s are obvious:

A higher flow rate of coolant thr= ough the system will result in a smaller delta T of the coolant. =C2=A0
The air doesn=E2=80=99t know or care about the coolant fl= ow rate. =C2=A0It is just removing heat from the exchanger regardless of ho= w that heat got there. =C2=A0The air flow was sufficient to keep temps unde= r control for the conditions of that flight. =C2=A0With the same air flow r= ate and power setting, an increase in OAT will result in an increase in the = exchanger (coolant) temp since the amount of heat removed is dependent on= the air flow rate and the air delta T. Increasing the power in addition to= the OAT with the same air flow rate will increase the coolant temps even mo= re.

This all assumes that the overall efficiency = of the heat exchanger is affected minimally by the coolant flow rate. =C2= =A0The efficiency of the exchanger should increase somewhat with an increas= e in coolant flow rate but it is difficult to predict by how much.

There is something to be said for changing only one thin= g at a time, though.

Steve Boese=C2=A0

On Feb 28, 2021= , at 12:47 PM, Finn Lassen finn.= lassen@verizon.net <f= lyrotary@lancaironline.net> wrote:

=EF=BB=BF

=E2=97=86 This message = was sent from a non-UWYO address. Please exercise caution when clicking li= nks or opening attachments from external sources.


Here's pictures of the small in- and outlets= . (looking into 5/8" and 3/4 OD tubes).

Finn

On 2/27/2021 11:29 PM, Finn Lassen finn.lassen@verizon.net wrote:
Yep, inlet/outlets on rads are very, very re= strictive. 7/64x1/2" (0.05 sqin or 1/4" diameter hole equivalent)) at best. = I was aware of it when I JB-welded 5/8" and 3/4" over existing tubes and "= just wanted to see how it would work" and then forgot about it.

Drilling holes in tank end plates I also found a small tube inside one tank = and baffles in both tanks. Now removed.

As for airflow, when I get new elbows welded onto the rads I'll collect new = data. I think the large delta is due to the very slow coolant flow -- stay= s in rads way too long (and thus not circulating through the engine fast en= ough).

Finn

On 2/27/2021 9:32 PM, Steven W. Boese SBoese@uwyo.edu wrote:
Finn,

If the "WTeng" sensor location is= somewhere in the engine block and not at the coolant outlet and the "WTout" = sensor is in the coolant exiting the engine, then the coolant flow rate th= rough the system may need to be increased by enlarging the radiator connections.=C3=AF=C2=BF=C2=BD Typically, it see= ms that at normal operating temps, the delta-T across the engine and across = the radiators is about 15 deg F.

It also would appear that the mass = air flow through the radiators may need to be increased since the air delt= a T is quite large and the temp of the air exiting the radiators is close t= o temp of the coolant exiting the radiators.=C3=AF=C2=BF=C2=BD If your OAT were increased to 100 deg F, you= could see "WTout" of ~250 deg F with the setup as it is now.

The attached plots show the effect = of changing only the air inlet and outlet areas of my system which has ~0.= 9" id plumbing to the single radiator.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD<= /div>

FWIW

Steve Boese
= 



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