X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2360761 for flyrotary@lancaironline.net; Sun, 30 Sep 2007 12:52:13 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta02.mail.rr.com with SMTP id <20070930165133.WHQK3965.cdptpa-omta02.mail.rr.com@edward2> for ; Sun, 30 Sep 2007 16:51:33 +0000 Message-ID: <000f01c80382$2a386570$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Slow Coolant Myth was [FlyRotary] Re: Oil Delta - T Date: Sun, 30 Sep 2007 12:51:36 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000C_01C80360.A2F4B8F0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_000C_01C80360.A2F4B8F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Mark, here is a more credible source about slow coolant flow than me. A common misconception is that if coolant flows too quickly through the = system, that it will not have time to cool properly. However the cooling = system is a closed loop, so if you are keeping the coolant in the = radiator longer to allow it to cool, you are also allowing it to stay in = the engine longer, which increases coolant temperatures. Coolant in the = engine will actually boil away from critical heat areas within the = cooling system if not forced through the cooling system at a = sufficiently high velocity. This situation is a common cause of = so-called "hot spots", which can lead to failures. Here is the URL if you want to read more http://www.stewartcomponents.com/tech_tips/Tech_Tips_3.htm Ed ----- Original Message -----=20 From: Mark Steitle=20 To: Rotary motors in aircraft=20 Sent: Sunday, September 30, 2007 10:09 AM Subject: [FlyRotary] Re: Oil Delta - T Ed,=20 Yes, I'm happy with the coolant temps. I wish the oil would allow a = little more margin, but 190* @ 5200 is ok for 90* OAT. I'll be gong out = to the airport in a while and I'll check the calibration on the coolant = sensors.=20 Mark Overcast with 40% chance of rain today. :-( =20 On 9/30/07, Ed Anderson wrote:=20 I suspect that you temp sensor location may be the problem rather = than calibration. If its outside the main flow channel, then its hard = to tell just how close or far off of the main flow temps it may be = registering. =20 On the other hand if your coolant engine outlet temp is measuring = only 161F (and assuming that is somewhere near the actual temp) then you = radiator is clearly doing its job by cooling down the coolant before it = enters the engine. When I am cruising at 5400 rpm my coolant temps = range from 155F-175F depending on OAT. This is temp out of the engine. = Since your temp is in the same ball park, it appears your radiator is = doing a good job especially given the 90F OAT. =20 Ed ----- Original Message -----=20 From: Mark Steitle=20 To: Rotary motors in aircraft=20 Sent: Saturday, September 29, 2007 10:13 PM Subject: [FlyRotary] Re: Oil Delta - T =20 Ed,=20 OK, I'll recallibrate the sensors ONE MORE TIME! They were = reading within a degree of each other before I relocated one of them. I = did take the time to verify the EC-2 sensor was reading correctly at = 212* during the switch. But I didn't check it lower than that. I'll = use ambient temp for a low reference. =20 I suspect the problem may be where one of the sensors is located. = The first sensor is located on the WP housing at the outlet from the = engine. Since that is one of the factory locations, I don't see any = problem there. The second sensor is on the WP housing inlet, but not on = the main line, it is on the one returing from the swirl tank, but is = very close to where the main WP inlet is located. It is fed by a line = that runs through the swirl tank from the outlet side of the radiator, = but at the top instead of the bottom (to draw any air out of the = radiator). Directly across from this fitting is the "hot" inlet to the = radiator. I'm sure that some of the coolant goes straight across the = core to the swirl tank fitting. (Yes, this is confusing me too) I = questioned the wisdom of putting the sensor where I did, but did it = anyway due to the ease of installation (No draining the cooling system, = no drilling, no tapping). Anyway, this was supposed to be a "temporary" = test setup. =20 So, it looks like I probably need to find a better place to locate = the second sensor. I'll check the accuracy of this sensor at around = 150* and see what it shows. If there is a significant error, I'll dive = into the EC-2 calibration system one more time (heaven help me). =20 Mark=20 =20 On 9/29/07, Ed Anderson wrote:=20 Mark, if you really had excess air flowing through your = radiators the coolant would drop more than 4 Deg F. In fact, the more = air flow the more coolant Delta T you would drop through the radiator. = So if you had something like 180F in and 120F out then I might suspect = too much air flow through the cores, but not with a drop of only 4 deg = F. In fact if that delta T is correct (which I suspect it is not), = then you would need tremendous coolant flow rates for it to carry away = the engine heat it needs to at 5200 rpm.=20 I did some back of envelope calculations.=20 IF your coolant flow was 30 GPM at 8.25 lb/gal coolant with a = 0.65 (50/50 mix) Cp, then a 4 degreeF drop in coolant temp would only be = getting rid of 644 BTU/Min.=20 At 5200 rpm and a 19:1 A/F ratio you would need to get rid of = approx 3100 BTU/Min through your radiator. I suspect that the 4 degree = drop you are measuring may be in error. I assume you are measuring temp = at radiator inlet (engine outlet) and radiator outlet (or engine inlet) = It would take something like a 20 deg coolant temp drop at 30 GPM flow = or a flow rate of 150 GPM at 4 deg drop to get rid of that much heat. =20 On the other hand if you were flowing 60 gpm of pure water and = had a 6.5F drop that would get rid of the required BTUs. I have no clue = as to the flow rate of a 20B water pump, but suspect my guess of 60 gpm = might be on the high side.=20 Since you are apparently cooling just fine with the radiators, = then : 1. My calculations are incorrect 2. Your coolant temp drop is more than 4 Fdeg 3. your flow rate is >50 gpm 4. You oil system is dumping the excess heat that your = radiators are not getting rid of. FWIW Ed ----- Original Message -----=20 From: Mark Steitle=20 To: Rotary motors in aircraft=20 Sent: Saturday, September 29, 2007 7:51 PM Subject: [FlyRotary] Re: Oil Delta - T =20 Tracy,=20 I flew again today. I'm still staying very close to the = airport and was forced to limit my altitude to 2500' due to clouds. OAT = was about 90* and oil got to 215, but came right down after leveling off = and settled in at 190*. The strange thing is the water temps in economy = cruise (5200 engine rpm, 1800 prop rpm) were in the 157* range. I'm = measuring water temp in and out. Water out was about 161*, so I'm = getting very little temp drop through the radiator. We're figuring that = this is probably due to too much air to the water radiator or too rapid = coolant flow through the radiator (I'm running the 20B pump). My main = pulley has been downsized, but I may also need to enlarge the wp pulley = a little to slow the flow. I'm considering doing a quick mod to check = this theory. If that's true, then my oil temps should drop because I = suspect airflow through the two radiators are fighting for the exit = space and the water radiator is winning. =20 Mark =20 On 9/29/07, Tracy Crook wrote:=20 Haven't had any 100+ days since installing the Renesis but = cooling is similar to the 2nd gen I had a few years ago when we had 10 = consecutive days of 100+ temps. Didn't have to wait it out but simply = limited power after initial climbout. Still had more ROC than most = certified planes at the reduced power setting. I start with around 2500 = FPM on a standard day and never had to settle for less than ~1000 fpm = due to heat issues.=20 Hope my 20B RV-8 does as well or better but I will install = spray bar for initial tests. Tracy (delayed 20B test schedule due to motorcycle = distraction) =20 On 9/27/07, Mark Steitle wrote:=20 Tracy, So, what do you call a "hot" day? In Austin, it is normal = during the summer for temps to be in the upper 90's and even above 100 = on occasion. I don't want to be grounded waiting for the Texas heat to = subside. I guess I could install a spray bar for summer flying. Right = now I can keep temps in the green up into the low 90's. Living in = Texas, I would like a little more margin than that. Not everyone can = swing a summer home in Colorado. ;-)=20 Mark S. (Just happy to be flying again.) =20 On 9/26/07, Tracy Crook wrote: = Engine will cool at any throttle setting that enables = the plane to fly. The coolant & oil temp curve looks about like the = power required curve of the airframe, minumum at around 95 mph and rises = on either side of that speed. Only exception is WOT at Vx on hot day. = Engine will exceed redline temps if this is maintained more than a = minute or so. Fortunately there is never any real need to do that. =20 Tracy =20 On 9/26/07, Mark Steitle wrote:=20 Tracy,=20 Is there a particular speed that you must reach before = your system cools? =20 Mark =20 On 9/26/07, Tracy Crook = wrote:=20 For another data point, the delta T on oil cooler = depends on power setting on my installation (no big surprise). It is = around 40 degrees F at higher power settings. Tracy =20 On 9/18/07, Mark Steitle = wrote:=20 For those that are flying (rotaries), I'm curious = as to what delta-T you're seeing across the oil cooler. And at what = speed you attain adequate cooling. Mark S. ------=_NextPart_000_000C_01C80360.A2F4B8F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Mark, here is a more credible source about slow = coolant=20 flow than me.
 
A common misconception is that if coolant flows too quickly = through the=20 system, that it will not have time to cool properly. However the cooling = system=20 is a closed loop, so if you are keeping the coolant in the radiator = longer to=20 allow it to cool, you are also allowing it to stay in the engine longer, = which=20 increases coolant temperatures. Coolant in the engine will actually boil = away=20 from critical heat areas within the cooling system if not forced through = the=20 cooling system at a sufficiently high velocity. This situation is a = common cause=20 of so-called "hot spots", which can lead to failures.

Here is the URL if you want = to read=20 more
 
http:= //www.stewartcomponents.com/tech_tips/Tech_Tips_3.htm
 
Ed
----- Original Message -----
From:=20 Mark = Steitle=20
Sent: Sunday, September 30, = 2007 10:09=20 AM
Subject: [FlyRotary] Re: Oil = Delta -=20 T

Ed,
Yes, I'm happy with the coolant temps.  I wish the oil would = allow a=20 little more margin, but 190* @ 5200 is ok for 90* OAT.  I'll be = gong out=20 to the airport in a while and I'll check the calibration on the = coolant=20 sensors.
 
Mark
Overcast with 40% chance of rain today.  :-(


 
On 9/30/07, Ed=20 Anderson <eanderson@carolina.rr.com&g= t;=20 wrote:=20
I suspect that you temp sensor location may = be the=20 problem rather than calibration.  If its outside the main flow = channel,=20 then its hard to tell just how close or far off of the main flow = temps it=20 may be registering.  
 
On the other hand if your coolant engine = outlet temp=20 is measuring only 161F (and assuming that is somewhere near the = actual temp)=20 then you radiator is clearly doing its job by cooling down the = coolant=20 before it enters the engine.  When I am cruising at 5400 rpm my = coolant=20 temps range from 155F-175F depending on OAT.  This is temp out = of the=20 engine.  Since your temp is in the same ball park, it appears = your=20 radiator is doing a good job especially given the 90F = OAT. =20
 
 
 
Ed
----- Original Message ----- =
From: = Mark = Steitle
To: Rotary = motors in=20 aircraft
Sent: Saturday, September = 29, 2007=20 10:13 PM
Subject: [FlyRotary] Re: = Oil Delta -=20 T

 
Ed,
OK, I'll recallibrate the sensors ONE MORE TIME!  They = were=20 reading within a degree of each other before I relocated one of=20 them.  I did take the time to verify the EC-2 sensor was = reading=20 correctly at 212* during the switch.  But I didn't check it = lower=20 than that.  I'll use ambient temp for a low reference.  =
 
I suspect the problem may be where one of the sensors is = located.  The first sensor is located on the WP housing at = the outlet=20 from the engine.  Since that is one of the factory locations, = I don't=20 see any problem there.  The second sensor is on the WP = housing inlet,=20 but not on the main line, it is on the one returing from the swirl = tank,=20 but is very close to where the main WP inlet is = located.  It is=20 fed by a line that runs through the swirl tank from the = outlet side=20 of the radiator, but at the top instead of the bottom (to draw any = air out=20 of the radiator).  Directly across from this fitting is the = "hot"=20 inlet to the radiator.  I'm sure that some of the coolant = goes=20 straight across the core to the swirl tank fitting. (Yes, this is=20 confusing me too)  I questioned the wisdom of putting the = sensor=20 where I did, but did it anyway due to the ease of installation (No = draining the cooling system, no drilling, no tapping).  = Anyway, this=20 was supposed to be a "temporary" test setup. 
 
So, it looks like I probably need to find a better place to = locate=20 the second sensor.  I'll check the accuracy of this = sensor at=20 around 150* and see what it shows.  If there is a significant = error,=20 I'll dive into the EC-2 calibration system one more time (heaven = help=20 me).   
 
Mark 

 
On 9/29/07, Ed=20 Anderson <eanderson@carolina.rr.com > wrote:=20
  Mark, if you really had = excess air=20 flowing through your radiators the coolant would drop more than = 4 Deg=20 F.  In fact, the more air flow the more coolant Delta T you = would=20 drop through the radiator.  So if you had something like = 180F in=20 and 120F out then I might suspect too much air flow through the = cores,=20 but not with a drop of only 4 deg F.   In fact if that = delta T=20 is correct (which I suspect it is not), then you would need = tremendous=20 coolant flow rates for it to carry away the engine heat it needs = to at=20 5200 rpm.
 
 I did some back of envelope=20 calculations. 
 
 IF your coolant flow was 30 GPM at = 8.25=20 lb/gal coolant with a 0.65 (50/50 mix) Cp, then a 4 degreeF drop = in=20 coolant temp would only be getting rid of 644=20 BTU/Min. 
 
 At 5200 rpm and a 19:1 A/F ratio = you would=20 need to get rid of approx 3100 BTU/Min through your = radiator.  I=20 suspect that the 4 degree  drop you are measuring may be in = error.  I assume you are measuring temp at radiator inlet = (engine=20 outlet) and radiator outlet (or engine inlet)   = It would=20 take something like a 20 deg coolant temp  drop at 30 GPM = flow or a=20 flow rate of 150 GPM at 4 deg drop to get rid of that much=20 heat.  
 
On the other hand if you were flowing 60 = gpm of=20 pure water and had a 6.5F drop that would get rid of the = required=20 BTUs.  I have no clue as to the flow rate of a 20B water = pump, but=20 suspect my guess of 60 gpm might be on the high side. =
 
Since you are apparently cooling just = fine with=20 the radiators, then :
 
1.  My calculations are=20 incorrect
2.  Your coolant temp drop is more = than 4=20 Fdeg
3.  your flow rate is >50 = gpm
4.  You oil system is dumping the = excess heat=20 that your radiators are not getting rid of.
 
FWIW
 
Ed
 
 
----- Original Message ----- =
From: Mark = Steitle
To: Rotary motors=20 in aircraft
Sent: Saturday, = September 29,=20 2007 7:51 PM
Subject: [FlyRotary] = Re: Oil=20 Delta - T

 
Tracy,
 
I flew again today.  I'm still staying very close to = the=20 airport and was forced to limit my altitude to 2500' = due to=20 clouds.  OAT was about 90* and oil got to 215, but came = right=20 down after leveling off and settled in at 190*.  The = strange=20 thing is the water temps in economy cruise (5200 engine rpm, = 1800 prop=20 rpm) were in the 157* range.  I'm measuring water temp in = and=20 out.  Water out was about 161*, so I'm getting very = little temp=20 drop through the radiator.  We're figuring that this is = probably=20 due to too much air to the water radiator or = too rapid=20 coolant flow through the radiator (I'm running the 20B=20 pump).  My main pulley has been downsized, but I may = also=20 need to enlarge the wp pulley a little to slow the flow.=20  I'm considering doing a quick mod to check this = theory.  If=20 that's true, then my oil temps should drop because I suspect = airflow=20 through the two radiators are fighting for the exit space and = the=20 water radiator is winning. 
 
Mark

 
On 9/29/07, Tracy Crook <tracy@rotaryaviation.com > = wrote:=20
Haven't had any 100+ days since installing the Renesis = but=20 cooling is similar to the 2nd gen I had a few years ago = when we=20 had 10 consecutive days of 100+ temps.  Didn't have to = wait it=20 out but simply limited power after initial climbout.  = Still had=20 more ROC than most certified planes at the reduced power=20 setting.  I start with around 2500 FPM on a standard = day and=20 never had to settle for less than ~1000 fpm due to heat = issues.=20
 
Hope my 20B RV-8 does as well or better but I will = install=20 spray bar for initial tests.
 
Tracy (delayed 20B test schedule due to motorcycle = distraction)

 
On 9/27/07, Mark Steitle <msteitle@gmail.com > wrote:=20
Tracy,
 
So, what do you call a "hot" day?  In Austin, it = is=20 normal during the summer for temps to be in the upper 90's = and=20 even above 100 on occasion.  I don't want to be = grounded=20 waiting for the Texas heat to subside.  I guess I = could=20 install a spray bar for summer flying.  Right now I = can keep=20 temps in the green up into the low 90's.  Living in=20 Texas, I would like a little more margin than = that.  Not=20 everyone can swing a summer home in=20 Colorado.   ;-)
 
Mark S.
(Just happy to be flying again.)
 


 
On 9/26/07, Tracy Crook <tracy@rotaryaviation.com > = wrote:=20
Engine will cool at any throttle setting that = enables the=20 plane to fly.  The coolant & oil temp curve = looks about=20 like the power required curve of the airframe, minumum = at around=20 95 mph and rises on either side of that speed.  = Only=20 exception is WOT at Vx on hot day.  Engine = will exceed=20 redline temps if this is maintained more than a = minute or=20 so.   Fortunately there is never any real = need to=20 do that. 
 
Tracy

 
On 9/26/07, Mark Steitle <msteitle@gmail.com > = wrote:=20
Tracy,
 
Is there a particular speed that you must reach = before=20 your system cools? 
 
Mark


 
On 9/26/07, Tracy Crook <tracy@rotaryaviation.com > = wrote:=20
For another data point, the delta T on oil = cooler=20 depends on power setting on my installation (no big=20 surprise).  It is around 40 degrees F at higher = power=20 settings.
 
Tracy

 
On 9/18/07, Mark Steitle <msteitle@gmail.com > = wrote:=20
For those that are flying (rotaries), I'm = curious as=20 to what delta-T you're seeing across the oil = cooler. =20 And at what speed you attain adequate = cooling.
 
Mark=20 = S.


=



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