X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qw-out-2122.google.com ([74.125.92.26] verified) by logan.com (CommuniGate Pro SMTP 5.3c4) with ESMTP id 4032486 for flyrotary@lancaironline.net; Sun, 20 Dec 2009 17:58:21 -0500 Received-SPF: pass receiver=logan.com; client-ip=74.125.92.26; envelope-from=rwstracy@gmail.com Received: by qw-out-2122.google.com with SMTP id 9so995254qwb.25 for ; Sun, 20 Dec 2009 14:57:44 -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=ltaTeZMVlHlyCTp6djMBqCPFRBByxb59E3tM2qcnt1A=; b=JInu4gL9ZHI2boxXdOM6uDdVlVA4KQ0wMuLgjGrWjzEe6MzQ7G5N/tK95K6XIzh/2U IYRu7IxMRjMW0LlVCapvK0Rc4BSL0KDVadDxRCsKmXi+mDc+yf3wRFg6OKh5FBQ0NLg6 /HYB7hqSiZxFRAUiVkEn8KScfcj8BfFjQXx4E= 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=EYmBOvW8LIM8BYQJFIrW14epb1IpW0KnoIlFwt1yERo9Exk59Ul/bf4sTFc50GUG+y CUF5NFOW1oFy45DCYSFFiNRTQjka6Fn2Emlb080qLPA9h++fh6lVTBI6v5RA1MvV7Sje SjbRUIweFg3vVx1tSvVoqq+2FAEQCh99Ef81U= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.15.85 with SMTP id j21mr3534534qaa.177.1261349864660; Sun, 20 Dec 2009 14:57:44 -0800 (PST) In-Reply-To: References: Date: Sun, 20 Dec 2009 17:57:44 -0500 X-Google-Sender-Auth: 52d9d730b82df076 Message-ID: <1b4b137c0912201457x67363e0fra158c206e692bb53@mail.gmail.com> Subject: Re: [FlyRotary] Re: Oil Cooling From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=000feaf00d0e9ee066047b30e683 --000feaf00d0e9ee066047b30e683 Content-Type: text/plain; charset=ISO-8859-1 I was ready to flight test the new oil cooler installation this morning (or thought I was). OAT was only 41 deg and it took a long idle time to warm up so used that time to check for oil leaks and saw no signs. The pattern of oil and water temps looked good so I had high hopes. Watched temps during takeoff run and continued to see good numbers. Climbed out to 500 ft and turned left to downwind and thought I smelled a slight whiff of hot oil. Looked over my shoulder and saw that I was sky-writing with a dense smoke trail so throttled back to high idle and did a hard 360 to the right to setup for a downwind landing (almost no wind). The only thing new was the oil cooler so I was scolding myself for installing this cheap POS and monitoring the oil pressure to see if this was going to cost me an engine overhaul. Pressure stayed at 55 - 60 PSI all through the landing so its OK. The oil cooking off the exhaust system did not ignite. Wonder if the poor burning qualities of synthetic oil is another good reason to use it? On the ground it looked like there was a couple of quarts of Mobile 1 dripping off the bottom of fuselage and left wing trailing edge. Popped the cowl top and the entire engine compartment is drenched in oil EXCEPT for the oil cooler core itself which is dry. The cooler turned out to be OK. The leak was from the bottom fitting on the cooler. It came equipped with -10 male fittings so I had installed -10 to -8 adapters to match the -8 hoses in the plane. The tightening procedure needed on these adapters had some pitfalls. I am always careful to use two wrenches on these fittings so as not to put torque on the cooler and damage it. These adapters require that the adapter be put on first using the two wrench method followed by the hose fitting to the adapter. BUT, one wrench needs to remain on the oil cooler fitting and the other on the hose fitting. I mistakenly put one on the adapter and one on the hose fitting. This results in loosening the adapter to cooler mating thread as you tighten the hose fitting. That's where the oil was coming from. Although this was a very brief flight on a cool day, I could tell from the trend on the oil & water temps that this cooler was going to work much better than the old one even though it is about 25% smaller in volume. Size really isn't everything. I properly installed the adapters and hose fittings and tested for leaks (none found) but didn't have enough daylight left for another flight test. Will try again tomorrow. Noticed one other oddity during this test. As soon as the O2 sensor got covered in oil, it quit working. These sensors actually have to 'see' the outside air at the cold end of the sensor. They compare the O2 in the air to the O2 in the exhaust and stop working when they can't. Tracy On Sun, Dec 20, 2009 at 4:58 PM, wrote: > I've been reading everything I could on cooling after my first attempt > flopped. Today I got my new cooling set up complete enough to ground test. I > copied (my version) from several of you, notably Dave Leonard's radiator and > Tracy's RV-4 oil cooler. Hat's off to Ed Anderson for all the under cowl > duct work on his website too. > I did achieve the stable temps at low power that Dave L told me are > critical. I just now got done running my RV-8 13B turbo for over 20 minutes > and got stabilized temps of 140F water and 170F oil. Once the oil cooler > thermostat opened, the temps dropped a few degrees. > Outside air temp 53F, 81% RH. Perhaps I should have run it longer, but > worries about leaks, fires etc. always make inspections prudent. > I suppose I have overcooled my plane, and added a big drag bucket on the > chin, but hopefully it will be safe to fly, and I can work back from 'too > cool' for more speed later. > After reading Tracy's post about adding the oil cooler exit duct, and > different flow resistance of the two coolers, I am glad I devided the two. > What I think lead to any success I might be having, is that I devided the > air suppies and outlets. The oil cooler gets 100% of the right cowl cheek > air, and the heated air exits the right side of the cowl. The radiator gets > air from the highest pressure point on the airframe: under the prop spinner. > I left out the upper lip because I believe this area has attached laminar > flow. The radiator exit air passes out the cowl bottom in the usual way. > The left cowl cheek is for Engine intake, plus surface cooling air on the > engine, turbo, & fuel system. It shares the bottom outlet with the radiator > air. I'm still working out the this duct. > . > > -----Original Message----- > From: Tracy Crook > To: Rotary motors in aircraft > Sent: Sat, Dec 19, 2009 5:46 pm > Subject: [FlyRotary] Re: Oil Cooling > > In retrospect it does seem obvious but I had never thought about matching > the airflow characteristics of the water and oil heat exchangers before. I > should know by tomorrow if this is just wishful thinking. > > Those heat exchanger volume figures you mentioned are at best just a rule > of thumb but still useful. Other details can make a world of difference. > For example, my RV-4 has had the same cooling components since day one but > cooling on that first flight looked hopeless. Now it is fine on even the > hottest days. Heat exchanger size isn't everything. > > My 20B has significantly less than 1.5 times the core volume of my 13B > installation. I'm hoping that better diffusers and other details will make > up for the relatively smaller heat exchangers. > > I can't think of any reason why the 20B would need more than 1.5 times the > 13Bs cooling requirement if all other factors are the same. That's a big if > of course. > > Tracy > > > On Sat, Dec 19, 2009 at 7:15 PM, George Lendich wrote: > >> Tracy, >> All that makes perfect sense and leads me to a question which has more >> curiosity value than anything else. What actual size did you settle on for >> the 20B. I'm curious to know if the 20B requires more cooling than 1.5 times >> a 13B. >> >> Calculating the ( rule of thumb) radiator size of approx 600 cu" for >> 200hp, giving 3 cu" per HP, the size of the Mazda oil cooler then gives a .8 >> per cu" per hp. I wondering if this holds true for the 20B and indeed the >> single rotor. >> George ( down under) >> >> Just an update on my RV-8 / 20B oil cooling experiments. >> >> On the theory that airflow patterns inside the cowl were blocking airflow >> through oil cooler, I installed a partial exit duct behind the radiator >> directing the airflow downward toward the cowl outlet. It looked very >> restrictive but flight tests showed almost no affect on water cooling (which >> is OK) but a significant improvement in oil cooling. I further restricted >> the airflow through the rad by putting some roof ridge vent material inside >> the inlet diffuser. This gave a tiny increase in water temp but a further >> improvement in oil cooling. Long story short, after several more tests it >> became apparent that back pressure under the cowl was having a major effect >> on the oil cooling. I have no idea why my instrument did not read the >> pressure correctly. It works fine on the bench and is properly referenced >> to the static system in the plane. The temptation is to keep changing the >> cooling outlet scheme until the internal cowl back pressure is low enough to >> get the cooling good enough. My belief is that this would lead to a very >> high drag solution. You may remember the experiment I did by flying with >> the cowl removed. The cooling was never a problem then (except perhaps too >> much cooling) but the drag was enormous. The fuel burn was 60% higher at >> the test airspeed of 130 mph. >> >> The conclusion I eventually came to was that the rad (because of it's >> relatively low air flow resistance) is hogging the airflow capability of the >> cowl cooling outlet. (cowl flap did not have enough effect to fix the >> problem). Keep in mind that the oil cooler is a thick AC evaporator core >> that is very restrictive. The current experiment is to replace it with a >> much less restrictive (to airflow) oil cooler. I found the largest cooler >> that would fit in the same location as the AC core and I'm using the same >> diffuser as before (slightly modified to fit the larger face of the new >> cooler). This cooler is only 2" thick and core volume is 30% less than the >> AC core. It is slightly larger in volume than an RX-7 cooler. Without any >> back pressure (flying with cowl off), the AC core had way more than enough >> cooling capacity (146 F oil temp on a 93 degree day) so I'm hoping that this >> smaller cooler will be enough. Should be ready to flight test it this week. >> >> I should point out another symptom. Power setting (and therefore airspeed) >> had very little effect on the cooling (i.e., it didn't get much hotter at >> high power as long as airspeed went up as well. Things got hot fast in >> climb however. This also indicated to me that cooling was limited by >> airflow through the system rather than by the oil cooler's ability to >> transfer the heat to the air. If the cooler is simply too small, more >> airflow will not help much. >> >> Tracy >> > > --000feaf00d0e9ee066047b30e683 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I was ready to flight test the new oil cooler installation this morning (or= thought I was).=A0=A0 OAT was only 41 deg and it took a long idle time to = warm up so used that time to check for oil leaks and saw no signs.=A0 The p= attern of oil and water temps looked good so I had high hopes.=A0 Watched t= emps during takeoff run and continued to see good numbers. Climbed out to 5= 00 ft and turned left to downwind and thought I smelled a slight whiff of h= ot oil.=A0 Looked over my shoulder and saw that I was sky-writing with a de= nse smoke trail so throttled back to high idle and did a hard 360 to the ri= ght to setup for a downwind landing (almost no wind).=A0=A0 The only thing = new was the oil cooler so I was scolding myself for installing this cheap P= OS and monitoring the oil pressure to see if this was going to cost me an e= ngine overhaul.=A0 Pressure stayed at 55 - 60 PSI all through the landing s= o its OK.=A0=A0 The oil cooking off the exhaust system did not ignite.=A0 W= onder if the poor burning qualities of synthetic oil is another good reason= to use it?

On the ground it looked like there was a couple of quarts of Mobile 1 d= ripping off the bottom of fuselage and left wing trailing edge. =A0 Popped = the cowl top and the entire engine compartment is drenched in oil EXCEPT fo= r the oil cooler core itself which is dry.=A0 The cooler turned out to be O= K.=A0 The leak was from the bottom fitting on the cooler.=A0 It came equipp= ed with -10 male fittings so I had installed -10 to -8 adapters to match th= e -8 hoses in the plane.=A0 The tightening procedure needed on these adapte= rs had some pitfalls.=A0 I am always careful to use two wrenches on these f= ittings so as not to put torque on the cooler and damage it.=A0 These adapt= ers require that the adapter be put on first using the two wrench method fo= llowed by the hose fitting to the adapter.=A0 BUT,=A0 one wrench needs to r= emain on the oil cooler fitting and the other on the hose fitting.=A0 I mis= takenly put one on the adapter and one on the hose fitting.=A0 This results= in loosening the adapter to cooler mating thread as you tighten the hose f= itting.=A0 That's where the oil was coming from.

Although this was a very brief flight on a cool day, I could tell from = the trend on the oil & water temps that this cooler was going to work m= uch better than the old one even though it is about 25% smaller in volume.= =A0 Size really isn't everything.

I properly installed the adapters and hose fittings and tested for leak= s (none found) but didn't have enough daylight left for another flight = test.=A0 Will try again tomorrow.=A0

Noticed one other oddity durin= g this test.=A0 As soon as the O2 sensor got covered in oil, it quit workin= g.=A0 These sensors actually have to 'see' the outside air at the c= old end of the sensor.=A0 They compare the O2 in the air to the O2 in the e= xhaust and stop working when they can't.=A0=A0

Tracy


On Sun, Dec 20, 2009 at 4:5= 8 PM, <shipchief= @aol.com> wrote:
I've been reading everything I could on cooling after my first att= empt flopped. Today I got my new cooling set up complete enough to ground t= est. I copied (my version) from several of you, notably Dave Leonard's = radiator and Tracy's RV-4 oil cooler. Hat's off to Ed Anderson for = all the under cowl duct work on his website too.
I did achieve the stable temps at low power that Dave L told me are cr= itical. I just now got done running my RV-8 13B turbo for over 20 minutes a= nd got stabilized temps of 140F water and 170F oil. Once the oil cooler the= rmostat opened, the temps dropped a few degrees.
Outside air temp 53F, 81% RH. Perhaps I should have run it longer, but= worries about leaks, fires etc. always make inspections prudent.
I suppose I have overcooled my plane, and added a big drag bucket on t= he chin, but hopefully it will be safe to fly, and I can work back from = 9;too cool' for more speed later.
After reading Tracy's post about adding the oil cooler exit duct, = and different flow resistance of the two coolers, =A0I am glad I devided th= e two.
What I think lead to any success I might be having, is that I devided = the air suppies and outlets. The oil cooler gets 100% of the right cowl che= ek air, and the heated air exits the right side of the cowl. The radiator g= ets air from the highest pressure point on the airframe: under the prop spi= nner. I left out the upper lip because I believe this area has attached lam= inar flow. The radiator exit air passes out the cowl bottom in the usual wa= y.
The left cowl cheek is for Engine intake, plus surface cooling air on = the engine, turbo, &=A0fuel system. It shares the bottom outlet with th= e radiator air. I'm still working out the this duct.
.

-----Original Message-----
From: Tracy Crook <tracy@rotaryaviation.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, Dec 19, 2009 5:46 pm
Subject: [FlyRotary] Re: Oil Cooling

In retrospect it does seem obvious but I had never thought about match= ing the airflow characteristics of the water and oil heat exchangers before= .=A0 I should know by tomorrow if this is just wishful thinking.

Those heat exchanger volume figures you mentioned are at best just a rule o= f thumb but still useful.=A0 Other details can make a world of difference.= =A0 For example, my RV-4 has had the same cooling components since day one = but cooling on that first flight looked hopeless.=A0 Now it is fine on even= the hottest days.=A0 Heat exchanger size isn't everything.

My 20B has significantly less than 1.5 times the core volume of my 13B inst= allation.=A0 I'm hoping that better diffusers and other details will ma= ke up for the relatively smaller heat exchangers.

I can't think of any reason why the 20B would need more than 1.5 times = the 13Bs cooling requirement if all other factors are the same.=A0 That'= ;s a big if of course.=A0

Tracy


On Sat, Dec 19, 2009 at 7:15 PM, George Lendich = <lendich@aanet.com.au> wrote:
Tracy,
All that makes perfect sense and leads= me to a question which has more curiosity value than anything else. What a= ctual size did you settle on for the 20B. I'm curious to know if the 20= B requires more cooling than=A01.5 times a 13B.
=A0
Calculating the ( rule of thumb) radia= tor size of approx=A0600 cu" fo= r 200hp, giving 3 cu" per HP,=A0the=A0size of the Mazda oil cooler the= n gives a .8 per cu" per hp. I wondering if this holds true for the 20= B and indeed the single rotor.
George ( down under)=A0

Just an update on my RV-8 / 20B=A0 oil cooling experiments.=A0

On the theory that airflow patterns inside the cowl were blocking airflow t= hrough oil cooler, I installed a partial exit duct behind the radiator dire= cting the airflow downward toward the cowl outlet.=A0 It looked very restri= ctive but flight tests showed almost no affect on water cooling (which is O= K)=A0 but a significant improvement in oil cooling.=A0=A0 I further restric= ted the airflow through the rad by putting some roof ridge vent material in= side the inlet diffuser.=A0 This gave a tiny increase in water temp but a f= urther improvement in oil cooling.=A0=A0 Long story short,=A0 after several= more tests it became apparent that back pressure under the cowl was having= a major effect on the oil cooling.=A0=A0 I have no idea why my instrument = did not read the pressure correctly.=A0 It works fine on the bench and is p= roperly referenced to the static system in the plane.=A0=A0 The temptation = is to keep changing the cooling outlet scheme until the internal cowl back = pressure is low enough to get the cooling good enough.=A0 My belief is that= this would lead to a very high drag solution.=A0 You may remember the expe= riment I did by flying with the cowl removed.=A0 The cooling was never a pr= oblem then (except perhaps too much cooling) but the drag was enormous.=A0 = The fuel burn was 60% higher at the test airspeed of 130 mph.

The conclusion I eventually came to was that the rad (because of it's r= elatively low air flow resistance) is hogging the airflow capability of the= cowl cooling outlet.=A0 (cowl flap did not have enough effect to fix the p= roblem). =A0 Keep in mind that the oil cooler is a thick AC evaporator core= that is very restrictive.=A0=A0 The current experiment is to replace it wi= th a much less restrictive (to airflow) oil cooler.=A0 I found the largest = cooler that would fit in the same location as the AC core and I'm using= the same diffuser as before (slightly modified to fit the larger face of t= he new cooler).=A0 This cooler is only 2" thick and core volume is 30%= less than the AC core.=A0 It is slightly larger in volume than an RX-7 coo= ler.=A0 Without any back pressure (flying with cowl off), the AC core had w= ay more than enough cooling capacity (146 F oil temp on a 93 degree day) so= I'm hoping that this smaller cooler will be enough.=A0 Should be ready= to flight test it this week.

I should point out another symptom. Power setting (and therefore airspeed) = had very little effect on the cooling=A0 (i.e., it didn't get much hott= er at high power as long as airspeed went up as well.=A0=A0 Things got hot = fast in climb however.=A0 This also indicated to me that cooling was limite= d by airflow through the system rather than by the oil cooler's ability= to transfer the heat to the air.=A0 If the cooler is simply too small, mor= e airflow will not help much.=A0

Tracy

--000feaf00d0e9ee066047b30e683--