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 2359821 for flyrotary@lancaironline.net; Sat, 29 Sep 2007 20:28:04 -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-omta06.mail.rr.com with SMTP id <20070930002728.ODGI3972.cdptpa-omta06.mail.rr.com@edward2> for ; Sun, 30 Sep 2007 00:27:28 +0000 Message-ID: <000701c802f8$afd1db10$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Oil Delta - T Date: Sat, 29 Sep 2007 20:27:29 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01C802D7.286CC3E0" 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_0004_01C802D7.286CC3E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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. 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. 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 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 =20 On 9/26/07, Tracy Crook wrote:=20 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_0004_01C802D7.286CC3E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
  Mark, if you really had excess air = flowing=20 through your radiators the coolant would drop more than 4 Deg F.  = In fact,=20 the more air flow the more coolant Delta T you would drop through the=20 radiator.  So if you had something like 180F in and 120F out then I = might=20 suspect too much air flow through the cores, but not with a drop of only = 4 deg=20 F.   In fact if that delta T is correct (which I suspect it is = not),=20 then you would need tremendous coolant flow rates for it to carry away = the=20 engine heat it needs to at 5200 rpm.
 
 I did some back of envelope=20 calculations. 
 
 IF your coolant flow was 30 GPM at 8.25 = lb/gal=20 coolant with a 0.65 (50/50 mix) Cp, then a 4 degreeF drop in coolant = temp would=20 only be getting rid of 644 BTU/Min. 
 
 At 5200 rpm and a 19:1 A/F ratio you would = need to=20 get rid of approx 3100 BTU/Min through your radiator.  I suspect = that the 4=20 degree  drop you are measuring may be in error.  I assume you = are=20 measuring temp at radiator inlet (engine outlet) and radiator = outlet=20 (or engine inlet)   It would take something like a 20 deg = coolant temp=20  drop at 30 GPM flow or a flow rate of 150 GPM at 4 deg drop to get = rid of=20 that much heat.  
 
On the other hand if you were flowing 60 gpm of = pure water=20 and had a 6.5F drop that would get rid of the required BTUs.  I = have no=20 clue as to the flow rate of a 20B water pump, but suspect my guess of 60 = gpm=20 might be on the high side.
 
Since you are apparently cooling just fine with = the=20 radiators, then :
 
1.  My calculations are = 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 that=20 your radiators are not getting rid of.
 
FWIW
 
Ed
 
 
----- Original Message -----
From:=20 Mark = Steitle=20
Sent: Saturday, September 29, = 2007 7:51=20 PM
Subject: [FlyRotary] Re: Oil = Delta -=20 T

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

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

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


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

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


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

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


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