X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from nskntmtas05p.mx.bigpond.com ([61.9.168.149] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6644469 for flyrotary@lancaironline.net; Wed, 18 Dec 2013 15:59:32 -0500 Received-SPF: pass receiver=logan.com; client-ip=61.9.168.149; envelope-from=neil.unger@bigpond.com Received: from nskntcmgw06p ([61.9.169.166]) by nskntmtas05p.mx.bigpond.com with ESMTP id <20131218205858.CVCO2026.nskntmtas05p.mx.bigpond.com@nskntcmgw06p> for ; Wed, 18 Dec 2013 20:58:58 +0000 Received: from UserPC ([138.130.64.170]) by nskntcmgw06p with BigPond Outbound id 38yt1n00c3gPrnN018yunz; Wed, 18 Dec 2013 20:58:58 +0000 X-Authority-Analysis: v=2.0 cv=Obga/2vY c=1 sm=1 a=gqe9j2JchM/wxrUwqLrHvg==:17 a=UW0NoIzLLIUA:10 a=JDadKst33uMA:10 a=1IlZJK9HAAAA:8 a=zM9wNM6nb-AA:10 a=Ia-xEzejAAAA:8 a=3oc9M9_CAAAA:8 a=7g1VtSJxAAAA:8 a=shEOQ7UeeKTJP99kZT4A:9 a=QEXdDO2ut3YA:10 a=Qa1je4BO31QA:10 a=EzXvWhQp4_cA:10 a=U8Ie8EnqySEA:10 a=q03TpU_jdw9g31Mw:21 a=vKLOpykkReeA30uW:21 a=1tbEcQXBsQ9pntZlSB4A:9 a=gb8PZ1BeJN8Qbxm6:21 a=-q_yFcv-Gvdh4y-B:21 a=gqe9j2JchM/wxrUwqLrHvg==:117 Message-ID: <9658C1268E68482399C253C9D0919DA9@UserPC> From: "Neil Unger" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Cooling Water Temp Date: Thu, 19 Dec 2013 07:58:46 +1100 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0018_01CEFC90.24C31D20" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3555.308 X-MimeOLE: Produced By Microsoft MimeOLE V15.4.3555.308 This is a multi-part message in MIME format. ------=_NextPart_000_0018_01CEFC90.24C31D20 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Steve, Not sure what you mean by a =E2=80=9Cbypass=E2=80=9D = 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 PMTo: 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. =20 One issue with the bypass thermostat was oscillation of the thermostat = valve 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 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 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 and 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 = thermostat. Although this eliminated the oscillation and pressure = pulses, 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 engine is unrestricted as is = always the case with a bypass thermostat, the temperature rise through = the engine at flight power 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 passage blocked, the temperature = 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 = entering 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 effective, and = significantly added to the pilot workload compared to using the bypass = 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 aircraft = so far in about 350 hr of operation.=20 Steve BoeseRV6A, 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 inspection, reassembled it and started = it up.I was planning to do a tethered trial at take off power, but the = weather was clear and cold with low overcast and no wind, so I taxied = about while 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 accelerate to 4850 RPM (2200+ prop RPM) before I let off the brakes = and concentrated 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 thermostat ended 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 thermostat? -------------------------------------------------------------------------= ------- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_0018_01CEFC90.24C31D20 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
Steve,
           &n= bsp;=20 Not sure what you mean by a =E2=80=9Cbypass=E2=80=9D thermostat.  = The ones in your photo=20 look like a normal thermostat with two holes drilled in the top = plate.  Can=20 you explain please, as I am totally ignorant.  Thanks Neil.
 
Sent: Wednesday, December 18, 2013 7:51 PM
Subject: [FlyRotary] Re: Cooling Water=20 Temp

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

 

One issue with the bypass thermostat was oscillation of the = thermostat valve=20 caused by the pressure difference across the bypass plate when the = bypass was=20 nearly closed.  This produced a clicking sound  in cruise and = was felt=20 as a shudder in the airframe.  Pulsing pressure was observed when=20 connecting a gauge to the area between the water pump and the = thermostat. =20 The pulses caused fatigue failure of the RX7 heater core located in the=20 cockpit.  This may or may not occur depending on the spring = constant of the=20 particular thermostat.  After modification of the thermostat bypass = plate=20 as shown in the attached photo, no oscillation or pressure pulsing has = been=20 observed and no damage to the replacement heater core has = occurred.  The=20 area of the bypass plate was reduced by the modification but it was = still large=20 enough to completely block the bypass passage.

 

Another possibility is to block the bypass passage and use a = non-bypass=20 thermostat.  Although this eliminated the oscillation and pressure = pulses,=20 this may not be the best option since the overall flow rate of coolant = through=20 the engine will be reduced until the thermostat is fully open.  = When the=20 coolant flowing through the engine is unrestricted as is always the case = with a=20 bypass thermostat, the temperature rise through the engine at flight = power=20 levels is always close to 10 degrees due to the mixing of warm coolant = from the=20 bypass and the cool coolant from the radiator.  If the temperature = cannot=20 be completely controlled by the thermostat, the temperature will be seen = to=20 rise, but the temperature difference through the engine will still be = close to=20 10 degrees.  With a non-bypass thermostat and the bypass passage = blocked,=20 the temperature difference between the coolant entering the engine block = and the=20 coolant exiting the block can be 60 degrees or more in cruise.

 

Eliminating the thermostat completely and blocking the bypass passage = is=20 another option.  In this case, the coolant temperature difference = entering=20 and exiting the engine will always be around 10 degrees or less, with = the=20 average temperature determined by the air side of the heat = exchanger. =20 Controlling the temperature with a cockpit adjustable cowl exit flap was = difficult, not completely effective, and significantly added to the = pilot=20 workload compared to using the bypass thermostat.

 

The few thermostat failures I have encountered were not sudden = complete=20 failures.  They resulted in the thermostat failing to completely = close when=20 cold.  I have not had a failure of the thermostat in the aircraft = so far in=20 about 350 hr of operation.

 
Steve=20 Boese
RV6A, 1986 = 13B NA,=20 RD1A, EC2

 

 

From: Rotary motors in aircraft=20 <flyrotary@lancaironline.net> on behalf of shipchief@aol.com=20 <shipchief@aol.com>
Sent: Tuesday, December 17, 2013 = 8:45=20 PM
To: Rotary motors in aircraft
Subject: = [FlyRotary]=20 Cooling Water Temp=20
 
Today I got a chance to sneak out = to the=20 airport and play.
The RV-8 cowl was off due to changing the oil, so I gave it a = pretty good=20 inspection, reassembled it and started it up.
I was planning to do a tethered trial at take off power, but the = weather=20 was clear and cold with low overcast and no wind, so I taxied about = while=20 waiting for the engine to warm up.
It never warmed up. The oil temp came up to about 156F, but the = water temp=20 came up to 128F while idling or slow taxiing. I did 4 aborted take off, = the=20 water temp rose to about 138F.
I have heard that this is not warm enough for full power. I did = accelerate=20 to 4850 RPM (2200+ prop RPM) before I let off the brakes and = concentrated on=20 rolling down the runway, lifting the tail and throttling back @ about 45 = MPH.=20
I don't have a thermostat in it right now, the one try with a = thermostat=20 ended in an overheat shut down before damage. maybe I didn't have all = the air=20 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=20 thermostat?

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Homepage:  http://www.flyrotary.com/
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