X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from willowsprings.uwyo.edu ([129.72.10.31] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTPS id 5453892 for flyrotary@lancaironline.net; Fri, 23 Mar 2012 11:55:46 -0400 Received-SPF: none receiver=logan.com; client-ip=129.72.10.31; envelope-from=SBoese@uwyo.edu Received: from ponyexpress-ht3.uwyo.edu (extlb.uwyo.edu [172.26.4.4]) by willowsprings.uwyo.edu (8.14.4/8.14.4) with ESMTP id q2NFt8UI014179 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL) for ; Fri, 23 Mar 2012 09:55:09 -0600 (MDT) (envelope-from SBoese@uwyo.edu) Received: from ponyexpress-m10.uwyo.edu ([fe80::60dd:cb9e:6f71:3d48]) by ponyexpress-ht3.uwyo.edu ([fe80::4cde:db24:a0a9:ba5%15]) with mapi id 14.01.0339.001; Fri, 23 Mar 2012 09:55:08 -0600 From: "Steven W. Boese" To: Rotary motors in aircraft Subject: RE: [FlyRotary] Randolph Smith newly on line Thread-Topic: [FlyRotary] Randolph Smith newly on line Thread-Index: AQHNCQUKu4tAO03Vj06XCYofc+OSdZZ3+7K2 Date: Fri, 23 Mar 2012 15:55:08 +0000 Message-ID: <3E8191F276108F4481AB0721BBA9269E05C37C49@ponyexpress-m10.uwyo.edu> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [75.249.182.219] Content-Type: multipart/alternative; boundary="_000_3E8191F276108F4481AB0721BBA9269E05C37C49ponyexpressm10u_" MIME-Version: 1.0 --_000_3E8191F276108F4481AB0721BBA9269E05C37C49ponyexpressm10u_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Randolf, The pressure you see depends on how your cooling system is set up. The fol= lowing discussion is for the case where the radiator cap and the pressure g= auge are located where they do not see additional pressure from the water p= ump. Below the boiling temperature of the coolant, the gauge pressure is p= rimarily due to expansion of the coolant in the closed system since the vap= or pressure of the coolant is low. If you have an air cushioned accumulator with a cushion volume greater than= the coolant volume increase that occurs below boiling temperature, then th= e pressure will gradually rise, the value depending on how much the air in = the cushion is compressed, which in turn depends on the volume of the air c= ushion. 5 psi at 160 degrees is a reasonable value for this type of system= and is similar to what I see. If you don't have an air cushion in the closed system, as soon as coolant e= xpansion begins due to the temperature increasing, the gauge pressure will = jump up to the radiator cap release pressure. The gauge pressure will stay= there as the temperature increases and the coolant continues to expand. T= he increased coolant volume will be expelled from the closed system, hopefu= lly into a recovery tank. As soon as there is even a slight decrease in te= mperature, the gauge pressure will drop to zero (negative if the gauge is c= apable of displaying that) and the expelled coolant will be drawn back into= the closed part of the system. This is assuming that the temperature is b= elow the coolant boiling point and you have a coolant recovery type of radi= ator cap. Steve Boese RV6A, 1986 13B NA, RD1A, EC2 ________________________________ From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of = Randolph [randolph7714@comcast.net] Sent: Friday, March 23, 2012 8:55 AM To: Rotary motors in aircraft Subject: [FlyRotary] Randolph Smith newly on line Hello All I have the first and second running of my 1988 13B on the nose of my nearly= completed AcroSport 2 biplane Lots of drag and not great speed expected, but lots of fun I lets hope. The set up is EC3/EM3/RD1C. with a 3 pass radiator all turning a Sterba 76X= 64 prop. I have enjoyed and found useful the Rotary feed with lots a greatly appreci= ated help from Ed Anderson directly. Only after final assembly will it be known if the engine mount length is ri= ght for weight and balance. Without wings and tail feathers it almost falls on its nose now. I am wondering if the water pressure sender is functioning properly...after= moderate speed ground (of course) running the oil and water temps show about 160 degrees, but water pressure = shows 5 psi Should I not expect much else until longer harder running or flight? Regards, Randolph --_000_3E8191F276108F4481AB0721BBA9269E05C37C49ponyexpressm10u_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Randolf,

 

The pressure you see depends on how your cooling system is set up. = The following discussion is for the case where the radiator cap and the pr= essure gauge are located where they do not see additional pressure from the= water pump.  Below the boiling temperature of the coolant, the gauge pressure is primarily due to expansion of t= he coolant in the closed system since the vapor pressure of the coolan= t is low. 

 

If you have an air cushioned accumulator with a cushion volume greater t= han the coolant volume increase that occurs below boiling temperature, then= the pressure will gradually rise, the value depending on how much the air = in the cushion is compressed, which in turn depends on the volume of the air cushion.  5 psi at 160 degre= es is a reasonable value for this type of system and is similar to what I s= ee.

 

If you don't have an air cushion in the closed system, as soon as coolan= t expansion begins due to the temperature increasing, the gauge pressure wi= ll jump up to the radiator cap release pressure.  The gauge pressure&n= bsp;will stay there as the temperature increases and the coolant continues to expand.  The increased coolant volume wi= ll be expelled from the closed system, hopefully into a recovery tank. = ; As soon as there is even a slight decrease in temperature, the gauge pres= sure will drop to zero (negative if the gauge is capable of displaying that) and the expelled coolant will be drawn back= into the closed part of the system.  This is assuming that the temper= ature is below the coolant boiling point and you have a coolant recovery ty= pe of radiator cap.

 

Steve Boese
RV6A, 1986 13B NA, RD1A, EC2
From: Rotary motors in aircraft [flyrotary= @lancaironline.net] on behalf of Randolph [randolph7714@comcast.net]
Sent: Friday, March 23, 2012 8:55 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Randolph Smith newly on line

Hel= lo All
I h= ave the first and second running of my 1988 13B on the nose of my nearly co= mpleted AcroSport 2 biplane
Lot= s of drag and not great speed expected, but lots of fun I lets hope.=
The= set up is EC3/EM3/RD1C. with a 3 pass radiator all turning a Sterba 76X64 = prop.
I h= ave enjoyed and found useful the Rotary feed with lots a greatly appreciate= d help from Ed Anderson directly.
Onl= y after final assembly will it be known if the engine mount length is right= for weight and balance.
Wit= hout wings and tail feathers it almost falls on its nose now.=
I a= m wondering if the water pressure sender is functioning properly...after mo= derate speed ground (of course)
run= ning the oil and water temps show about 160 degrees, but water pressure sho= ws 5 psi 
Sho= uld I not expect much else until longer harder running or flight?
 
Reg= ards,
Ran= dolph
--_000_3E8191F276108F4481AB0721BBA9269E05C37C49ponyexpressm10u_--