X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qmta07.emeryville.ca.mail.comcast.net ([76.96.30.64] verified) by logan.com (CommuniGate Pro SMTP 5.4c2) with ESMTP id 4922986 for flyrotary@lancaironline.net; Fri, 25 Mar 2011 21:52:24 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.30.64; envelope-from=hoursaway1@comcast.net Received: from omta07.emeryville.ca.mail.comcast.net ([76.96.30.59]) by qmta07.emeryville.ca.mail.comcast.net with comcast id Pdpj1g0071GXsucA7droUF; Sat, 26 Mar 2011 01:51:48 +0000 Received: from sz0081.ev.mail.comcast.net ([76.96.26.137]) by omta07.emeryville.ca.mail.comcast.net with comcast id Pdrn1g00F2xV6SL8UdrnFr; Sat, 26 Mar 2011 01:51:47 +0000 Date: Sat, 26 Mar 2011 01:51:47 +0000 (UTC) From: hoursaway1@comcast.net To: Rotary motors in aircraft Message-ID: <1380755502.2729410.1301104307722.JavaMail.root@sz0081a.emeryville.ca.mail.comcast.net> In-Reply-To: <1286171740.2729341.1301104248836.JavaMail.root@sz0081a.emeryville.ca.mail.comcast.net> Subject: Re: [FlyRotary] Re: Radiator Caps [FlyRotary] Re: On the subject of installations...Coolant Pressure MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_2729409_703090128.1301104307721" X-Originating-IP: [68.61.190.35] X-Mailer: Zimbra 6.0.5_GA_2431.RHEL5_64 (ZimbraWebClient - IE8 (Win)/6.0.5_GA_2427.RHEL4) ------=_Part_2729409_703090128.1301104307721 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Snap-on tools ( & other aftermarket tool suppliers ) has a test set for che= cking coolant for combustion gases.=C2=A0Very easy to use, very accurate, w= arm up eng., shut off eng., test coolant, be advised =C2=A0HOT COOLANT. =C2= =A0No Sun-n-fun this year, won't be in FL until the last two weeks of April= .=C2=A0=C2=A0=C2=A0Getting some=C2=A0transition training time in RV7A Subi = tomorrow.=C2=A0 =C2=A0David R. Cook=C2=A0 RV6A Rotary=C2=A0 Lansing MI.=20 ----- Original Message -----=20 From: "Ed Anderson" =20 To: "Rotary motors in aircraft" =20 Sent: Friday, March 25, 2011 10:41:36 AM=20 Subject: [FlyRotary] Re: Radiator Caps [FlyRotary] Re: On the subject of in= stallations...Coolant Pressure=20 Bill,=20 One check is if you can, is to remove the cap while the engine is running a= nd if you can maintain a SAFE distance from the spinning prop to observe th= e top of your coolant and see whether:=20 1.=C2=A0 There are any bubbles coming up (stready stream)=20 2.=C2=A0 Any sign of oil slick on top (coming in with combustion gases)=20 My coolant pressure will jump from zero to 21 psi instantly upon start up b= ecause I have no air bubble in my coolant system.=C2=A0 Hydrostatic "lock" = (no air bubble to absorb any pressure waves) amplifies any pressure present= -=C2=A0 until the engine block and coolant system heat up and expand a tin= y bit - then within a minute or two the coolant drops back down to a nomina= l 5-7 psi.=20 Ed=20 From: Bill Bradburry=20 Sent: Friday, March 25, 2011 9:49 AM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Radiator Caps [FlyRotary] Re: On the subject of in= stallations...Coolant Pressure=20 I have a 21 lb cap on my system for this very purpose.=C2=A0 I don=E2=80=99= t presently have a coolant recovery tank and if the cap burps, I could lose= coolant overboard.=C2=A0 I am rethinking this and plan to install a coolan= t recovery tank as well.=20 By the way, on the high coolant pressure, in surfing the web I have found t= hat this problem is most likely caused by combustion gasses getting into th= e coolant.=C2=A0 That would mean a busted o-ring.=C2=A0 I have been in deni= al that this is the cause because I don=E2=80=99t want to tear the engine d= own.=C2=A0 Today I plan to see if I can find any coolant coming out of a sp= arkplug hole.=C2=A0 Fingers are crossed!=20 Bill B=20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Ed Anderson=20 Sent: Friday, March 25, 2011 8:27 AM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Radiator Caps [FlyRotary] Re: On the subject of instal= lations...Coolant Pressure=20 One thing to keep in mind about the pressure rating of the radiator cap you= are using.=C2=A0 All are rated relative to a standard sea level ambinent p= ressure.=C2=A0 This means that he air pressure itself is contributing 14.7 = psi at sea level.=C2=A0=20 So at sea level when your differential pressure coolant gauge is reading 10= psi - the absolute pressure in your coolant system is then =C2=A014.7 + 10= =3D 24.7 psi.=C2=A0 Now if you are flying at 8000 MSL your ambient pressur= e is approx 1/2 at sea level.=C2=A0 So your 14.7 psi CAP now has the lesser= capacity of 7.3 + 10 =3D 17.3 psi absolute pressure capacity - somewhat le= ss than the 24.7 psi absolute it had at sea level.=20 When you increase in altitude this component naturally decreases.=C2=A0 So = while a 14.7 psi CAP may work fine at sea level, more than one person found= that at=C2=A0altitude=C2=A0 that rating was=C2=A0 insufficient and some co= olant was lost.=20 I personally would not fly with less than a 21 psi cap and currently fly wi= th a 24 psi radiator cap.=20 There is another factor that occurred to me.=C2=A0 Once a=C2=A0hot coolant = system blows the relief valve on the cap, that lowers the pressure inside t= he system, superheated (>212F) coolant can quickly flash to steam and furth= er cause lost of coolant.=C2=A0 So a Higher PSI cap can lessen the chance o= f that happening.=C2=A0=20 FWIW=20 Ed=20 From: Bill Bradburry=20 Sent: Thursday, March 24, 2011 5:30 PM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: On the subject of installations...Coolant Pressure= =20 Lynn ,=20 You have hit my quandary squarely on the head.=C2=A0 Assuming that the pres= sure was zero at room temp and rose to say 6-7 pounds at 200 degrees, and a= ssume that the flow restriction in the system caused a pressure rise of abo= ut 2 pounds at 2000 rpm and a pressure rise of, say, 6-7 pounds at 6000 rpm= .=C2=A0 Under that scenario, you would have a pressure that ran at between = 7-9 pounds at 2000 and rose to 12-14 pounds at 6000.=C2=A0 Those pressures = would be easily contained with the stock cap of 14 pounds.=C2=A0 And the pr= essure would be constantly changing with rpm and possibly temp of the syste= m as you were under power or not.=20 I have a 21 pound cap.=C2=A0 My system climbs smartly to the top and stays = there.=C2=A0 No fluctuation with rpm, no real fluctuation at temp because i= t has already hit the 21 pounds before the engine is actually hot.=C2=A0 (a= round 190)=20 Something is wrong and I don=E2=80=99t understand what it is.=20 Bobby=20 I am going to insert answers to your questions in your msg below.=20 Bill B=20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Bobby J. Hughes=20 Sent: Thursday, March 24, 2011 1:57 PM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: On the subject of installations...Coolant Pressure= =20 Bill,=20 This is all I can think of at the moment.=20 Are you running a thermostat or did you plug the hole between the inlets an= d outlets of the water pump?=20 No thermostat.=C2=A0 The Renesis has a thermostat tower which is too tall t= o fit under my cowl, so I removed it and fabricated a flat plate with two 1= .25 aluminum tubes for the inlet and outlet of the water pump.=C2=A0 That h= ole you are referencing exists in the tower, but not in my plate.=20 If plugged did you drill a small hole in the plug to allow air a place to e= scape? I used a #30 drill.=20 Any air in my system would have to be carried to the highest point, (radiat= or cap) then be forced by pressure to the bottom of the swirl tank where it= would be trapped.=C2=A0 This seems to be working because I have found that= after I open the system for some reason, the level in the swirl tank will = go down and there is never any air at the top of the radiator.=20 After an engine run is the radiator the same temperature at the inlet / out= let / bottom and top? If I have trapped air only part of my radiator gets h= ot to the touch. Dual pass barrier leaking?=20 Seems to be.=C2=A0 I have mistakenly laid my arm on the top of the radiator= after a run=E2=80=A6usually I manage to get off pretty fast!=C2=A0 :>)=C2= =A0 I can not see into the radiator tank on the barrier side.=C2=A0 It is p= ossible it could be leaking.=C2=A0 I suppose if there was a rag in the thin= g it could be trapped here also.=C2=A0 I have no way to see in there even i= f the hose was removed.=C2=A0 I would need some kind of flexible camera or = something like that.=20 Use an extra CHT channel and clamp it to the inlet of your radiator to meas= ure Delta T.=20 Good idea.=C2=A0 I will have to rig one up.=C2=A0 I don=E2=80=99t have an e= xtra now.=20 My water pressure does not vary that much in operation. But it does hold a = little pressure for a few days after shutdown. =C2=A01-2 psi.=20 What is your pressure during operation?=C2=A0 What is the pressure cap rati= ng?=C2=A0 Does it vary at all with temp and/or rpm?=C2=A0 Mine is maxed out= ..always!=20 What size hoses? I=E2=80=99m running 1in.=20 The RX-8 uses 1.25 hoses.=C2=A0 I stuck with that size as well.=20 Where are you measuring water pressure? =C2=A0=20 The hose that comes off the top of the rear iron goes to the top of the rad= iator, just below the cap. A tee in this line has the water pressure sender= in it.=C2=A0 The radiator cap is just a cap, not a pressure cap.=C2=A0 The= outlet in the radiator neck goes to the bottom of the swirl tank.=20 Is your pressure cap on the bleed / swirl tank?=20 Yes.=20 Any pictures of the plumbing?=20 Not of the current setup.=20 Bobby=20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Bill Bradburry=20 Sent: Thursday, March 24, 2011 10:23 AM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] On the subject of installations...Coolant Pressure=20 I need some help with figuring out my cooling problems.=20 Just so it doesn=E2=80=99t get lost in the following BS, I need to state th= at I think the problem is related to the coolant pressure.=C2=A0 It seems t= o me to be way too high.=C2=A0 I am beginning to think that the coolant is = somehow partially blocked.=20 Now the rest of the story=E2=80=A6.=20 After I did the flight described in the attached email, I installed an open= ing in the bottom of the cowl that would work something like a cowl flap th= at is permanently open.=C2=A0 The new opening is 9 inches by 5 inches or 54= sq in..=C2=A0 There is a flare in front of the opening that is at an angle= of 45 degrees and extends down into the airstream about 4 inches.=C2=A0 (i= t is 6 inches long.)=C2=A0 This opening is in addition to two 6 X 6 opening= s, one of which has a 3 inch diameter exhaust pipe in it.=20 This helped a little, but nothing like I expected it would.=C2=A0 The press= ure inside the radiator inlet dropped from 10 inches of water to 8 inches o= f water.=C2=A0 (by the way, Steve was right about it being inches of water = and not inches of Hg.)=20 The pressure after the radiator and inside the cowl dropped to 8 inches as = well.=C2=A0 The temperature of the water dropped to 208 and the oil a coupl= e of degrees.=C2=A0 Neither of these had the result that I expected.=20 My water pressure cap is rated at 21 lbs.=C2=A0 I have not calibrated the s= ender that came with my EM-2 and it shows 3 lbs when the engine is cold.=C2= =A0 I assume that this is zero.=C2=A0 When in flight the pressure climbs to= 24 lbs and stays there.=C2=A0 I assume that at this point, the cap is at 2= 1 lbs and is bleeding off air.=C2=A0 There is about a pint to a quart of ai= r above the coolant in the bleed tank.=20 This morning I ran the engine on the ground for about 10-15 minutes at an r= pm of 3000 to 3200.=C2=A0 The OAT was 75 degrees.=20 I read the temps and pressures every minute or two during the run.=C2=A0 I = hope this doesn=E2=80=99t get jumbled during transmission.=20 Oil temp =E2=80=93 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A080 = =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0103=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 130=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 13= 9=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 1= 44=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 155=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 162=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 165=20 Air temp after cooler - =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A097=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 109= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 122=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 129=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 133=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 134= =20 Water temp -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 86=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 126=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 161=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 173=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 178=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 190=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 198=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0 199=20 Air temp after rad -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 109=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 133=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 157=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 169=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 179=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 183=20 Water pressure -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 2=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 11= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 17=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A020=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 21=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 24=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=20 I noticed that the water pressure could be brought from 2 lbs to 9 lbs by c= hanging the rpm while the engine was still relatively cool=20 What should I expect for water pressure at lower temps and how could I go a= bout making a determination that the water passages are clear?=20 I am beginning to think that a rag has been left either in the engine or th= e radiator.=C2=A0 I have never torn the engine down and I sent the radiator= out to have a leak repair a couple of years ago.=C2=A0 It is a double pass= radiator.=C2=A0 I can look into the end that has both sides connected thru= the radiator cap neck, but not into the inlet and outlet end.=20 Suggestions???=20 Thanks,=20 Bill B=20 From: Bill Bradburry [mailto:bbradburry@bellsouth.net]=20 Sent: Sunday, March 20, 2011 5:29 PM=20 To: 'Rotary motors in aircraft'=20 Subject: On the subject of installations...=20 My water temp has been running between 199 and 217, depending on the OAT.= =C2=A0 The oil is pretty steady at around 175.=C2=A0 Today I finally got to= fly with pressure probes inside the cowling.=C2=A0 I was all set to try an= d enlarge the inlet to the radiator to solve the problem.=C2=A0 It turns ou= t that =E2=80=9Cin=E2=80=9D is not the problem, it is =E2=80=9Cout=E2=80=9D= that is the problem!=20 I have 10 inches of Hg pressure in the radiator inlet and 10 inches of Hg o= n the outlet side as well as the same pressure everywhere I measured inside= the cowl.=C2=A0 I need to open up the cowl some so more air can get out.= =C2=A0 I had considered a cowl flap but that would not work in this instanc= e because the problem is at cruise.=C2=A0 I need a permanent opening.=C2=A0= I am considering louvers and I am looking for a source.=C2=A0 I know some = of you are using them.=C2=A0 Where did you get them and how are they instal= led so that they look ok?=20 I am also considering some kind of flare around the exit area to create a l= ow pressure area to help suck air out.=C2=A0 Do any of you have those and d= o they seem to work?=20 While I look into this, I also need to do something about my muffler=E2=80= =A6Thank you, Bobby!=20 I wonder about that spiral muffler some of you are trying??=20 Bill B=C2=A0 9 hours and counting=E2=80=A6=20 By the way, I was considering putting a 1 or 2 inch wide piece of cardboard= across the bottom of the oil cooler to partially block it in the hopes tha= t more air would then flow through the radiator.=C2=A0 Sort of like trucker= s do with the radiator in cold weather.=C2=A0 What opinions do you have abo= ut that idea?=C2=A0 I realize it would make more sense if the oil was reall= y cool, but I think the oil might not get much hotter if an inch or so was = blocked.=C2=A0 What do you think??? ------=_Part_2729409_703090128.1301104307721 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable <= div style=3D'font-family: Arial; font-size: 12pt; color: #000000'>Snap-on t= ools ( & other aftermarket tool suppliers ) has a test set for checking= coolant for combustion gases. Very easy to use, very accurate, warm u= p eng., shut off eng., test coolant, be advised  HOT COOLANT.  No= Sun-n-fun this year, won't be in FL until the last two weeks of April.&nbs= p;  Getting some transition training time in RV7A Subi tomor= row.   David R. Cook  RV6A Rotary  Lansing MI.
-----= Original Message -----
From: "Ed Anderson" <eanderson@carolina.rr.co= m>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>= ;
Sent: Friday, March 25, 2011 10:41:36 AM
Subject: [FlyRotary] Re: R= adiator Caps [FlyRotary] Re: On the subject of installations...Coolant Pres= sure

Bill,
 
One check is if you can, is to remove the cap while= the engine is running and if you can maintain a SAFE distance from the spi= nning prop to observe the top of your coolant and see whether:
 
1.  There are any bubbles coming up (stready s= tream)
2.  Any sign of oil slick on top (coming in wi= th combustion gases)
 
My coolant pressure will jump from zero to 21 psi i= nstantly upon start up because I have no air bubble in my coolant system.&n= bsp; Hydrostatic "lock" (no air bubble to absorb any pressure waves) amplif= ies any pressure present -  until the engine block and coolant system = heat up and expand a tiny bit - then within a minute or two the coolant dro= ps back down to a nominal 5-7 psi.
 
Ed

Sent: Friday, March 25, 2011 9:49 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Radiator Caps [FlyRotary] Re: On the s= ubject of installations...Coolant Pressure

I have a 21 lb cap on= my system for this very purpose.  I don=E2=80=99t presently have a co= olant recovery tank and if the cap burps, I could lose coolant overboard.&n= bsp; I am rethinking this and plan to install a coolant recovery tank as we= ll.

 <= /P>

By the way, on the hi= gh coolant pressure, in surfing the web I have found that this problem is m= ost likely caused by combustion gasses getting into the coolant.  That= would mean a busted o-ring.  I have been in denial that this is the c= ause because I don=E2=80=99t want to tear the engine down.  Today I pl= an to see if I can find any coolant coming out of a sparkplug hole.  F= ingers are crossed!

 <= /P>

Bill B<= /P>

 <= /P>

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Friday, March 25, 2011 8:2= 7 AM
To: Rotary motors i= n aircraft
Subject: [Fly= Rotary] Radiator Caps [FlyRotary] Re: On the subject of installations...Coo= lant Pressure

 

One thing to keep in mind about the pressure rati= ng of the radiator cap you are using.  All are rated relative to a sta= ndard sea level ambinent pressure.  This means that he air pressure it= self is contributing 14.7 psi at sea level. 

 

So at sea level when your differential pressure c= oolant gauge is reading 10 psi - the absolute pressure in your coolant syst= em is then  14.7 + 10 =3D 24.7 psi.  Now if you are flying at 800= 0 MSL your ambient pressure is approx 1/2 at sea level.  So your 14.7 = psi CAP now has the lesser capacity of 7.3 + 10 =3D 17.3 psi absolute press= ure capacity - somewhat less than the 24.7 psi absolute it had at sea level= .

 

When you increase in altitude this component natu= rally decreases.  So while a 14.7 psi CAP may work fine at sea level, = more than one person found that at altitude  that rating was = ; insufficient and some coolant was lost.

 

I personally would not fly with less than a 21 ps= i cap and currently fly with a 24 psi radiator cap.

 

There is another factor that occurred to me. = ; Once a hot coolant system blows the relief valve on the cap, that lo= wers the pressure inside the system, superheated (>212F) coolant can qui= ckly flash to steam and further cause lost of coolant.  So a Higher PS= I cap can lessen the chance of that happening. 

 

FWIW

 

Ed

 

Sent: Thursday, March 24, 2011 5:30 PM

Subject: [FlyRotary] Re: On the subject o= f installations...Coolant Pressure

 

Lynn,

 <= /P>

You have hit my quand= ary squarely on the head.  Assuming that the pressure was zero at room= temp and rose to say 6-7 pounds at 200 degrees, and assume that the flow r= estriction in the system caused a pressure rise of about 2 pounds at 2000 r= pm and a pressure rise of, say, 6-7 pounds at 6000 rpm.  Under that sc= enario, you would have a pressure that ran at between 7-9 pounds at 2000 an= d rose to 12-14 pounds at 6000.  Those pressures would be easily conta= ined with the stock cap of 14 pounds.  And the pressure would be const= antly changing with rpm and possibly temp of the system as you were under p= ower or not.

 <= /P>

I have a 21 pound cap= .  My system climbs smartly to the top and stays there.  No fluct= uation with rpm, no real fluctuation at temp because it has already hit the= 21 pounds before the engine is actually hot.  (around 190)

 <= /P>

Something is wrong an= d I don=E2=80=99t understand what it is.

 <= /P>

Bobby

 <= /P>

I am going to insert = answers to your questions in your msg below.

 <= /P>

Bill B<= /P>

 <= /P>

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bobby J. Hughes
<= B>Sent: Thursday, March 24, 20= 11 1:57 PM
To: Rotary mo= tors in aircraft
Subject: [FlyRotary] Re: On the subject of installations...Coolant Pressure=

 

Bill,

 <= /P>

This is all I can thi= nk of at the moment.

 <= /P>

Are you running a the= rmostat or did you plug the hole between the inlets and outlets of the wate= r pump?

 <= /P>

No thermostat.  The = Renesis has a thermostat tower which is too tall to fit under my cowl, so I= removed it and fabricated a flat plate with two 1.25 aluminum tubes for th= e inlet and outlet of the water pump.  That hole you are referencing e= xists in the tower, but not in my plate.

 <= /P>

If plugged did you dr= ill a small hole in the plug to allow air a place to escape? I used a #30 d= rill.

 <= /P>

Any air in my system woul= d have to be carried to the highest point, (radiator cap) then be forced by= pressure to the bottom of the swirl tank where it would be trapped.  = This seems to be working because I have found that after I open the system = for some reason, the level in the swirl tank will go down and there is neve= r any air at the top of the radiator.

 <= /P>

After an engine run i= s the radiator the same temperature at the inlet / outlet / bottom and top?= If I have trapped air only part of my radiator gets hot to the touch. Dual= pass barrier leaking?

 <= /P>

Seems to be.  I have= mistakenly laid my arm on the top of the radiator after a run=E2=80=A6usua= lly I manage to get off pretty fast!  :>)  I can not see into = the radiator tank on the barrier side.  It is possible it could be lea= king.  I suppose if there was a rag in the thing it could be trapped h= ere also.  I have no way to see in there even if the hose was removed.=   I would need some kind of flexible camera or something like that.

 <= /P>

Use an extra CHT chan= nel and clamp it to the inlet of your radiator to measure Delta T.

 <= /P>

Good idea.  I will h= ave to rig one up.  I don=E2=80=99t have an extra now.

 <= /P>

My water pressure doe= s not vary that much in operation. But it does hold a little pressure for a= few days after shutdown.  1-2 psi.

 <= /P>

What is your pressure dur= ing operation?  What is the pressure cap rating?  Does it vary at= all with temp and/or rpm?  Mine is maxed out..always!

 <= /P>

What size hoses? I=E2= =80=99m running 1in.

 <= /P>

The RX-8 uses 1.25 hoses.=   I stuck with that size as well.

 <= /P>

Where are you measuri= ng water pressure?  

 <= /P>

The hose that comes off t= he top of the rear iron goes to the top of the radiator, just below the cap= . A tee in this line has the water pressure sender in it.  The radiato= r cap is just a cap, not a pressure cap.  The outlet in the radiator n= eck goes to the bottom of the swirl tank.

 <= /P>

Is your pressure cap = on the bleed / swirl tank?

 <= /P>

Yes.

 <= /P>

Any pictures of the p= lumbing?

 <= /P>

Not of the current setup.=

 <= /P>

Bobby

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry
Sent: Thursday, March 24, 201= 1 10:23 AM
To: Rotary mo= tors in aircraft
Subject: [FlyRotary] On the subject of installations...Coolant Pressure

 

I need some help with= figuring out my cooling problems.

 <= /P>

Just so it doesn=E2= =80=99t get lost in the following BS, I need to state that I think the prob= lem is related to the coolant pressure.  It seems to me to be way too = high.  I am beginning to think that the coolant is somehow partially b= locked.

 <= /P>

Now the rest of the s= tory=E2=80=A6.

 <= /P>

After I did the fligh= t described in the attached email, I installed an opening in the bottom of = the cowl that would work something like a cowl flap that is permanently ope= n.  The new opening is 9 inches by 5 inches or 54 sq in..  There = is a flare in front of the opening that is at an angle of 45 degrees and ex= tends down into the airstream about 4 inches.  (it is 6 inches long.)&= nbsp; This opening is in addition to two 6 X 6 openings, one of which has a= 3 inch diameter exhaust pipe in it.

 <= /P>

This helped a little,= but nothing like I expected it would.  The pressure inside the radiat= or inlet dropped from 10 inches of water to 8 inches of water.  (by th= e way, Steve was right about it being inches of water and not inches of Hg.= )

The pressure after th= e radiator and inside the cowl dropped to 8 inches as well.  The tempe= rature of the water dropped to 208 and the oil a couple of degrees.  N= either of these had the result that I expected.

 <= /P>

My water pressure cap= is rated at 21 lbs.  I have not calibrated the sender that came with = my EM-2 and it shows 3 lbs when the engine is cold.  I assume that thi= s is zero.  When in flight the pressure climbs to 24 lbs and stays the= re.  I assume that at this point, the cap is at 21 lbs and is bleeding= off air.  There is about a pint to a quart of air above the coolant i= n the bleed tank.

 <= /P>

This morning I ran th= e engine on the ground for about 10-15 minutes at an rpm of 3000 to 3200.&n= bsp; The OAT was 75 degrees.

 <= /P>

I read the temps and = pressures every minute or two during the run.  I hope this doesn=E2=80= =99t get jumbled during transmission.

 <= /P>

Oil temp =E2=80=93 &n= bsp;            = ;        80     = ; 103      130     &= nbsp;        139    =          144    = ;       155     &nbs= p;    162         16= 5

Air temp after cooler= -             =   97       109   &nb= sp;            =             &nb= sp;   122         &n= bsp;  129          133&nb= sp;        134

 <= /P>

Water temp - &nb= sp;            =     86       126  &n= bsp;   161         &= nbsp;    173        =      178        = ;   190          198=           199

Air temp after rad -&= nbsp;           &nbs= p;       109      13= 3            &n= bsp;            = ;       157     &nbs= p;     169       &nb= sp;  179           1= 83

 <= /P>

Water pressure - = ;            2 =          11    =     17          = ;     20       =         21     =             &nb= sp;          24  &nb= sp;  

 <= /P>

I noticed that the wa= ter pressure could be brought from 2 lbs to 9 lbs by changing the rpm while= the engine was still relatively cool

 <= /P>

What should I expect = for water pressure at lower temps and how could I go about making a determi= nation that the water passages are clear?

 <= /P>

I am beginning to thi= nk that a rag has been left either in the engine or the radiator.  I h= ave never torn the engine down and I sent the radiator out to have a leak r= epair a couple of years ago.  It is a double pass radiator.  I ca= n look into the end that has both sides connected thru the radiator cap nec= k, but not into the inlet and outlet end.

 <= /P>

Suggestions???=

 <= /P>

Thanks,=

 <= /P>

Bill B<= /P>

 <= /P>

From: Bill Bradburry [mailto:bbradburry@bellsouth.net]
Sent: Sunday, March 20, 2011 5:29 PM
<= B>To: 'Rotary motors in aircra= ft'
Subject: On the subj= ect of installations...

 

My water temp has bee= n running between 199 and 217, depending on the OAT.  The oil is prett= y steady at around 175.  Today I finally got to fly with pressure prob= es inside the cowling.  I was all set to try and enlarge the inlet to = the radiator to solve the problem.  It turns out that =E2=80=9Cin=E2= =80=9D is not the problem, it is =E2=80=9Cout=E2=80=9D that is the problem!=

 <= /P>

I have 10 inches of H= g pressure in the radiator inlet and 10 inches of Hg on the outlet side as = well as the same pressure everywhere I measured inside the cowl.  I ne= ed to open up the cowl some so more air can get out.  I had considered= a cowl flap but that would not work in this instance because the problem i= s at cruise.  I need a permanent opening.  I am considering louve= rs and I am looking for a source.  I know some of you are using them.&= nbsp; Where did you get them and how are they installed so that they look o= k?

 <= /P>

I am also considering= some kind of flare around the exit area to create a low pressure area to h= elp suck air out.  Do any of you have those and do they seem to work?<= /SPAN>

 <= /P>

While I look into thi= s, I also need to do something about my muffler=E2=80=A6Thank you, Bobby!

 <= /P>

I wonder about that s= piral muffler some of you are trying??

 <= /P>

Bill B  9 hours = and counting=E2=80=A6

 <= /P>

By the way, I was con= sidering putting a 1 or 2 inch wide piece of cardboard across the bottom of= the oil cooler to partially block it in the hopes that more air would then= flow through the radiator.  Sort of like truckers do with the radiato= r in cold weather.  What opinions do you have about that idea?  I= realize it would make more sense if the oil was really cool, but I think t= he oil might not get much hotter if an inch or so was blocked.  What d= o you think???

<= /DIV>
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