X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [207.46.163.206] (HELO na01-bl2-obe.outbound.protection.outlook.com) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTPS id 6644618 for flyrotary@lancaironline.net; Wed, 18 Dec 2013 17:37:38 -0500 Received-SPF: none receiver=logan.com; client-ip=207.46.163.206; envelope-from=SBoese@uwyo.edu Received: from BLUPR05MB200.namprd05.prod.outlook.com (10.255.191.14) by BLUPR05MB198.namprd05.prod.outlook.com (10.255.191.12) with Microsoft SMTP Server (TLS) id 15.0.842.7; Wed, 18 Dec 2013 22:36:50 +0000 Received: from BLUPR05MB200.namprd05.prod.outlook.com ([169.254.12.222]) by BLUPR05MB200.namprd05.prod.outlook.com ([169.254.12.71]) with mapi id 15.00.0842.003; Wed, 18 Dec 2013 22:36:50 +0000 From: "Steven W. Boese" To: Rotary motors in aircraft Subject: RE: [FlyRotary] Re: Cooling Water Temp Thread-Topic: [FlyRotary] Re: Cooling Water Temp Thread-Index: AQHO/DQ0o71IPL/fHkiTz05fFmcs35pahuCl Date: Wed, 18 Dec 2013 22:36:49 +0000 Message-ID: <905e1c005007475cbf57c351b685da16@BLUPR05MB200.namprd05.prod.outlook.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [70.196.197.116] x-forefront-prvs: 0064B3273C x-forefront-antispam-report: SFV:NSPM;SFS:(10009001)(189002)(377454003)(199002)(66066001)(80022001)(19580405001)(83322001)(76576001)(76796001)(80976001)(16236675002)(15395725003)(81342001)(15202345003)(74366001)(76786001)(65816001)(54316002)(19580395003)(56776001)(77982001)(90146001)(74706001)(76482001)(59766001)(53806001)(81542001)(56816005)(47736001)(50986001)(47976001)(4396001)(49866001)(69226001)(15188445003)(31966008)(74662001)(74502001)(47446002)(51856001)(46102001)(75432001)(83072002)(85852003)(77096001)(74876001)(2656002)(74316001)(81816001)(15975445006)(85306002)(87266001)(81686001)(79102001)(54356001)(33646001)(63696002)(87936001)(24736002)(80792004);DIR:OUT;SFP:1101;SCL:1;SRVR:BLUPR05MB198;H:BLUPR05MB200.namprd05.prod.outlook.com;CLIP:70.196.197.116;FPR:;RD:InfoNoRecords;MX:1;A:1;LANG:en; Content-Type: multipart/alternative; boundary="_000_905e1c005007475cbf57c351b685da16BLUPR05MB200namprd05pro_" MIME-Version: 1.0 X-OriginatorOrg: uwyo.edu --_000_905e1c005007475cbf57c351b685da16BLUPR05MB200namprd05pro_ Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Neil, The bypass thermostat is the stock Mazda thermostat. There is a drawing at= tached to the end of 11 Mar 2012 message 57598 in the archives showing the = bypass thermostat operation: http://lancaironline.net/lists/flyrotary/Message/57598.html?Language=3D This message can also be found by searching the archives for "thermostat": I modified the 13B water pump housing and thermostat cover to use the 180 d= egree Renesis thermostat rather than the 190 degree one used in the 13B. Steve ________________________________ From: Rotary motors in aircraft on behalf of = Neil Unger Sent: Wednesday, December 18, 2013 1:58 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Cooling Water Temp Steve, Not sure what you mean by a =93bypass=94 thermostat. The ones= in your photo look like a normal thermostat with two holes drilled in the = top plate. Can you explain please, as I am totally ignorant. Thanks Neil. From: Steven W. Boese Sent: Wednesday, December 18, 2013 7:51 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Cooling Water Temp For me, the best solution to controlling the coolant temp has been to use a= 180 degree bypass type thermostat. On a recent flight with 20 degree OAT,= the coolant temperature, as measured in the water pump housing just below = the thermostat, rapidly warmed up to 183 degrees for idle and taxi, peaked = at 190 degrees during take off and climb, and stabilized at 185 degrees in = cruise. One issue with the bypass thermostat was oscillation of the thermostat valv= e caused by the pressure difference across the bypass plate when the bypass= was nearly closed. This produced a clicking sound in cruise and was felt= as a shudder in the airframe. Pulsing pressure was observed when connecti= ng a gauge to the area between the water pump and the thermostat. The puls= es caused fatigue failure of the RX7 heater core located in the cockpit. T= his may or may not occur depending on the spring constant of the particular= thermostat. After modification of the thermostat bypass plate as shown in= the attached photo, no oscillation or pressure pulsing has been observed a= nd no damage to the replacement heater core has occurred. The area of the = bypass plate was reduced by the modification but it was still large enough = to completely block the bypass passage. Another possibility is to block the bypass passage and use a non-bypass the= rmostat. Although this eliminated the oscillation and pressure pulses, thi= s may not be the best option since the overall flow rate of coolant through= the engine will be reduced until the thermostat is fully open. When the c= oolant flowing through the engine is unrestricted as is always the case wit= h a bypass thermostat, the temperature rise through the engine at flight po= wer levels is always close to 10 degrees due to the mixing of warm coolant = from the bypass and the cool coolant from the radiator. If the temperature= cannot be completely controlled by the thermostat, the temperature will be= seen to rise, but the temperature difference through the engine will still= be close to 10 degrees. With a non-bypass thermostat and the bypass passa= ge blocked, the temperature difference between the coolant entering the eng= ine block and the coolant exiting the block can be 60 degrees or more in cr= uise. Eliminating the thermostat completely and blocking the bypass passage is an= other option. In this case, the coolant temperature difference entering an= d exiting the engine will always be around 10 degrees or less, with the ave= rage temperature determined by the air side of the heat exchanger. Control= ling the temperature with a cockpit adjustable cowl exit flap was difficult= , not completely effective, and significantly added to the pilot workload c= ompared to using the bypass thermostat. The few thermostat failures I have encountered were not sudden complete fai= lures. They resulted in the thermostat failing to completely close when co= ld. I have not had a failure of the thermostat in the aircraft so far in a= bout 350 hr of operation. Steve Boese RV6A, 1986 13B NA, RD1A, EC2 ________________________________ From: Rotary motors in aircraft on behalf of = shipchief@aol.com Sent: Tuesday, December 17, 2013 8:45 PM To: Rotary motors in aircraft Subject: [FlyRotary] Cooling Water Temp Today I got a chance to sneak out to the airport and play. The RV-8 cowl was off due to changing the oil, so I gave it a pretty good i= nspection, reassembled it and started it up. I was planning to do a tethered trial at take off power, but the weather wa= s clear and cold with low overcast and no wind, so I taxied about while wai= ting for the engine to warm up. It never warmed up. The oil temp came up to about 156F, but the water temp = came up to 128F while idling or slow taxiing. I did 4 aborted take off, the= water temp rose to about 138F. I have heard that this is not warm enough for full power. I did accelerate = to 4850 RPM (2200+ prop RPM) before I let off the brakes and concentrated o= n rolling down the runway, lifting the tail and throttling back @ about 45 = MPH. I don't have a thermostat in it right now, the one try with a thermostat en= ded in an overheat shut down before damage. maybe I didn't have all the air= pockets burped out. So I might have removed it prematurely. What does the group say about warm up before take off, and about using a th= ermostat? ________________________________ -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.= html --_000_905e1c005007475cbf57c351b685da16BLUPR05MB200namprd05pro_ Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

Neil,

 

The bypass thermostat is the stock Mazda thermostat.  There is a dr= awing attached to the end of 11 Mar 2012 message 57598 in the archives show= ing the bypass thermostat operation:

 

http://lancaironline.net/lists/flyrotary/Message/57598.html?Langua= ge=3D

 

This message can also be found by searching the archives for "therm= ostat": 

 

I modified the 13B water pump housing and thermostat cover to use the 18= 0 degree Renesis thermostat rather than the 190 degree one used in the= 13B.

 

Steve

 

From: Rotary motors in ai= rcraft <flyrotary@lancaironline.net> on behalf of Neil Unger <neil= .unger@bigpond.com>
Sent: Wednesday, December 18, 2013 1:58 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Cooling Water Temp
 
Steve,
           &nbs= p; Not sure what you mean by a =93bypass=94 thermostat.  The ones in y= our photo look like a normal thermostat with two holes drilled in the top p= late.  Can you explain please, as I am totally ignorant.  Thanks = Neil.
 
Sent: Wednesday, December 18, 2013 7:51 PM
Subject: [FlyRotary] Re: Cooling Water Temp

For me, the best solution to controlling the coolant temp has been to us= e a 180 degree bypass type thermostat.  On a recent flight with 20 deg= ree OAT, the coolant temperature, as measured in the water pump housing jus= t below the thermostat, rapidly warmed up to 183 degrees for idle and taxi, peaked at 190 degrees during take off= and climb, and stabilized at 185 degrees in cruise. 

 

One issue with the bypass thermostat was oscillation of the thermostat v= alve caused by the pressure difference across the bypass plate when the byp= ass was nearly closed.  This produced a clicking sound  in cruise= and was felt as a shudder in the airframe.  Pulsing pressure was observed when connecting a gauge to the area between = the water pump and the thermostat.  The pulses caused fatigue failure = of the RX7 heater core located in the cockpit.  This may or may not oc= cur depending on the spring constant of the particular thermostat.  After modification of the thermostat bypass p= late as shown in the attached photo, no oscillation or pressure pulsing has= been observed and no damage to the replacement heater core has occurred.&n= bsp; The area of the bypass plate was reduced by the modification but it was still large enough to completely block the = bypass passage.

 

Another possibility is to block the bypass passage and use a non-bypass = thermostat.  Although this eliminated the oscillation and pressure pul= ses, this may not be the best option since the overall flow rate of coolant= through the engine will be reduced until the thermostat is fully open.  When the coolant flowing through the e= ngine is unrestricted as is always the case with a bypass thermostat, the t= emperature rise through the engine at flight power levels is always close t= o 10 degrees due to the mixing of warm coolant from the bypass and the cool coolant from the radiator.  If t= he temperature cannot be completely controlled by the thermostat, the tempe= rature will be seen to rise, but the temperature difference through the eng= ine will still be close to 10 degrees.  With a non-bypass thermostat and the bypass passage blocked, the temperatu= re difference between the coolant entering the engine block and the coolant= exiting the block can be 60 degrees or more in cruise.

 

Eliminating the thermostat completely and blocking the bypass passage is= another option.  In this case, the coolant temperature difference ent= ering and exiting the engine will always be around 10 degrees or less, with= the average temperature determined by the air side of the heat exchanger.  Controlling the temperature with= a cockpit adjustable cowl exit flap was difficult, not completely effectiv= e, and significantly added to the pilot workload compared to using the bypa= ss thermostat.

 

The few thermostat failures I have encountered were not sudden complete = failures.  They resulted in the thermostat failing to completely close= when cold.  I have not had a failure of the thermostat in the aircraf= t so far in about 350 hr of operation.

 
Steve Boe= se
RV6A, 198= 6 13B NA, RD1A, EC2

 

 

From: Rotary motors in ai= rcraft <flyrotary@lancaironline.net> on behalf of shipchief@aol.com &= lt;shipchief@aol.com>
Sent: Tuesday, December 17, 2013 8:45 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Cooling Water Temp
 
Today I got a chance to sneak out to the airport and play.
The RV-8 cowl was off due to changing the oil, so I gave it a pretty g= ood inspection, reassembled it and started it up.
I was planning to do a tethered trial at take off power, but the weath= er was clear and cold with low overcast and no wind, so I taxied about whil= e waiting for the engine to warm up.
It never warmed up. The oil temp came up to about 156F, but the water = temp came up to 128F while idling or slow taxiing. I did 4 aborted take off= , the water temp rose to about 138F.
I have heard that this is not warm enough for full power. I did accele= rate to 4850 RPM (2200+ prop RPM) before I let off the brakes and conce= ntrated on rolling down the runway, lifting the tail and throttling back @ = about 45 MPH.
I don't have a thermostat in it right now, the one try with a thermost= at ended in an overheat shut down before damage. maybe I didn't have all th= e air pockets burped out. So I might have removed it prematurely.
What does the group say about warm up before take off, and about using= a thermostat?

--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyro= tary/List.html
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