X-Virus-Scanned: clean according to Sophos on Logan.com From: Received: from omr-m01.mx.aol.com ([64.12.143.75] verified) by logan.com (CommuniGate Pro SMTP 6.1.2) with ESMTPS id 7680195 for flyrotary@lancaironline.net; Fri, 08 May 2015 10:24:28 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.143.75; envelope-from=ARGOLDMAN@aol.com Received: from mtaomg-aao02.mx.aol.com (mtaomg-aao02.mx.aol.com [172.27.21.16]) by omr-m01.mx.aol.com (Outbound Mail Relay) with ESMTP id 2866A7053335D for ; Fri, 8 May 2015 10:23:53 -0400 (EDT) Received: from core-aba04b.mail.aol.com (core-aba04.mail.aol.com [172.27.22.4]) by mtaomg-aao02.mx.aol.com (OMAG/Core Interface) with ESMTP id DFE3A38000084 for ; Fri, 8 May 2015 10:23:52 -0400 (EDT) Full-name: ARGOLDMAN Message-ID: Date: Fri, 8 May 2015 10:23:52 -0400 Subject: Re: [FlyRotary] Re: Return to Flight To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_cd1f0.52970129.427e20f8_boundary" X-Mailer: AOL 9.7 sub 4049 X-Originating-IP: [67.167.236.80] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20140625; t=1431095033; bh=suZq/N4GstH0rejOFqm40NY4D2wMQN1GxaHfWCkl75k=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=I5FwTM3YTC8vy1vu1rLD9PYKctVAppdItXZbm+lSWtWxmCa4370cs2nv8HvA1waVY snIGEEhjq2kyHsngheRyNAit+gDhHa4s+TfAwkuX1jzRJ2AWWCJpE0RkEBxVr/B7AZ OWtPHgQ2CQ0Qvc8LgFcRfnfAM/RGBYniM46WCb7c= x-aol-sid: 3039ac1b1510554cc6f855b0 --part1_cd1f0.52970129.427e20f8_boundary Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en Al, thanks for the explan.. =20 That's what I thought. I think, perhaps incorrectly that people think that= =20 the setting on the cap is the governing factor of the pressure in the =20 system. =20 =20 My system has the air buffer in the reservoir. Gas taps from the high poin= t=20 of the engine and the radiator feed into the top of the reservoir. =20 Rich =20 =20 In a message dated 5/8/2015 8:46:50 A.M. Central Daylight Time, =20 flyrotary@lancaironline.net writes: =20 wrot= e:=20 =20 =20 Jeff,=20 Congratulations on getting back in the air. That =C2=BD quart of coolant= may=20 have been trapped air that purged during flight. =20 Bobby Hughes=20 N416AS- =20 RV10 223 hrs=20 =20 =20 From: Rotary motors in aircraft [mailto:_flyrotary@lancaironline.net_=20 (mailto:flyrotary@lancaironline.net) ]=20 Sent: Monday, May 04, 2015 7:53 AM To: Rotary motors in aircraft Subject: [FlyRotary] Return to Flight Yesterday 3-May, my bird got airborne once again on its maiden flight=20 after 2+ years rebuilding. I had a friend test-pilot fly it while I was= flight=20 engineer watching the gauges. Flight controls and rigging were reported= =20 to be good and the engine performed flawlessly. The oil temperature was= =20 stable around 160F (Mazda oil cooler in series with a Fluidyne) but again= the=20 water temperature was high reaching 210F by circuit height so we backed= =20 off the throttle, did a touch and go with a 500=E2=80=99 circuit and park= ed it. One=20 unusual result was the cooling system pressure was only at 5-6 psi; with= =20 the high temperature it should have been 15-16 psi. Removed the cowlings= and=20 found no leaks of either oil or glycol. I checked the coolant level and= =20 it was down, requiring 1/2 quart to top it up. I also looked at my pinche= d=20 duct and think it needs more pinching, so am already starting to modify= that=20 =E2=80=93 hope to get another test flight in before the weekend.=20 Jeff=20 This message, and the documents attached hereto, is intended only for the= =20 addressee and may contain privileged or confidential information. Any=20 unauthorized disclosure is strictly prohibited. If you have received this= =20 message in error, please notify us immediately so that we may correct our= =20 internal records. Please then delete the original message. Thank you. =20 This message, and the documents attached hereto, is intended only for the= =20 addressee and may contain privileged or confidential information. Any=20 unauthorized disclosure is strictly prohibited. If you have received this= =20 message in error, please notify us immediately so that we may correct our= =20 internal records. Please then delete the original message. Thank you. =20 --part1_cd1f0.52970129.427e20f8_boundary Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
Al, thanks for the explan..
 
That's what I thought. I think, perhaps incorrectly that people think= that=20 the setting on the cap is the governing factor of the pressure in the=20 system.
 
 
My system has the air buffer in the reservoir. Gas taps from the high= point=20 of the engine and the radiator feed into the top of the reservoir.
 
Rich
 
In a message dated 5/8/2015 8:46:50 A.M. Central Daylight Time,=20 flyrotary@lancaironline.net writes:
<I am a littl= e confused=20 about the system pressure being able to read what the pressure cap setti= ng is,=20 and somehow adjusting the pressure, under normal <operating=20 conditions.
 
Sorry if I didn=E2=80=99t explain well.= If you fill your=20 cooling system completely to the top, no air in sys anywhere, then warm= up=20 engine to 200F will result in seeing a pressure reading of 16 psi. Fluid= will=20 leave sys and go to your overflow. Now, let the engine completely cool.= But=20 this time, remove 2 cups of fluid. This time when you warm up engine, yo= u see=20 max pressure of 10 psi. No fluid will overflow. This is because that two= cups=20 of air acts like a giant spring. Air molecules are far apart and easily= =20 compress.
 
I fly with 2 cups of air in system. It= =E2=80=99s so much=20 safer. Since the air is above the engine, out of the block flow, it has= no=20 significant neg affect on cooling. The safety is due to flying way more= =20 informed. A cooling sys completely stacked full of fluid will mask a num= ber of=20 common problems, but the two cup of air method makes all the problems cl= ear=20 with gobs of advance notice. For example, I was deliberately very abusiv= e to=20 my first engine. Overheated it time and again during ground run experime= nts.=20 Suddenly I saw 22 psi, where normally it never exceeds 12 psi. That pres= sure=20 only lasted for 5 seconds. Sure nuff, I review the data, this was caused= by my=20 finally getting a compression leak into cooling sys. It only leaked for= 5=20 seconds after applying full throttle. Would not have been able to observ= e this=20 if I had a fully filled cooling sys. 
 
<are you usin= g an=20 unpressurized reservoir
 
Not needed with two cup of air sys. Coo= lant never=20 exits sys unless temps exceed 220 F or so.
 
<purpose of= the cap's=20 setting
 
Cap pressure rating gives you boil over= =20 protection. Boil over is a big deal. When it happens it=E2=80=99s darn= near=20 irreversible. Pretty remarkable actually. You reduce power and it contin= ues to=20 boil fluid out of system. I use 22 psi cap. With my 50/50 mix, that mean= s boil=20 over can=E2=80=99t occur until I reach a whopping 289F. 16 psi cap is a= good choice.=20 That would boil over at 252 F and you are not running at needlessly high= =20 pressure.
 
 
<Would it not= be true=20 that in an "Ideal" system that a popoff cap would theoretically not be= =20 necessary?
 
I need that popoff on the off chance th= at I=20 achieve very high operating temp. If I reach 289F, then my 2 cups of air= are=20 fully compressed. I would then have completely fluid filled sys that nee= ds to=20 dump water to prevent rad from blowing open.
 
-al wick
 
 
Would it not be true that in an "Ideal" system that a popoff cap wo= uld=20 theoretically not be necessary?
 
Thanks for your input
 
Rich
 
In a message dated 5/6/2015 10:16:33 A.M. Central Daylight Time,=20 flyrotary@lancaironline.net writes:
Hi Jeff. I=E2=80=99ve done lot=E2=80=99s of experimenting with co= oling sys. Tough to=20 explain all this, but I=E2=80=99ll give it a try:
Pretty clear you saw 6 psi only because you took off with 3+ cups= of=20 air in the system. If you=E2=80=99d taken off with 2 cups of air, then= pressure=20 would have been 9 psi. 1 cup, 14 psi. No air in system, then you would= have=20 seen rated cap pressure (16 psi in your case).
 
Sorry to say, the pressure you see has no significant effect on= cooling=20 efficiency (heat transfer). The next time you fly, since you=E2=80=99v= e removed most=20 of that air, you will still see 210F. Just like before. There=E2=80=99= s one huge=20 exception to that statement, that=E2=80=99s if you have air in sys tha= t can=E2=80=99t move=20 to a high point out of the flow. In that case air in sys has huge nega= tive=20 effect. Causes local boiling when it passes hot areas and inflates coo= ling=20 temp.
 
You don=E2=80=99t have to fly to prove these concepts. Ground run= ning at idle=20 is all that=E2=80=99s needed. Let=E2=80=99s assume all air is removed.= Then letting engine=20 warm up to 180 F will result in rapid pressure rise to 16 psi (rated= cap=20 pressure). Fluid will exit system. With 2 cups of air in sys, that sam= e 180F=20 will yield slow rise in pressure to only 9 psi. No fluid will leave sy= s.=20
 
A good cooling design pretends air is stuck in block, so you add= a path=20 for that air to rise out of the block coolant flow. This is called a= dynamic=20 bleed. Air is automatically removed from engine coolant flow. Super lo= w risk=20 way to fly as you no longer care if air is in system. It=E2=80=99s can= =E2=80=99t affect=20 cooling.
 
It=E2=80=99s a bit higher risk to fly without dynamic air bleed,= you just make=20 darn sure you purge all air from block sys prior to flight. Applying= vacuum=20 to rad cap is great way to remove air.
 
One of the ironies about cooling design is that air that resides= above=20 engine flow is a safety asset. For example, your cap is highest point= in sys=20 and you have 2 cups of air under cap. Big safety advantage simply beca= use=20 your pressure gage is then a great predictor of how well your sys is= doing.=20 A leak will be detected long before overheating. A bunch of other asse= ts to=20 this design.
 
Conversely, air in engine flow has overwhelming negative affect.= Temps=20 soar and risks boil over.
 
Clear as mud eh?
 
Fwiw
 
-al wick
 
 
From:=20 Jeff Whaley

Dave,=20 I can=E2=80=99t argue with your adequate theory; I have that for my oi= l cooling=20 system, along with the temperature-controlled Mazda oil cooler, I neve= r=20 worry about oil temperature.

It=E2=80=99s=20 the practical application of that theory to the radiator installation= that=20 has plagued me from the beginning =E2=80=A6 after the next flight I=E2= =80=99ll know where I=20 stand and if there=E2=80=99s still a problem, then radical change may= have to be the=20 recipe.

Jeff

 

From: David= Leonard=20 [mailto:flyrotary@lancaironline.net]
Sent: Tuesday, May 05,= 2015=20 9:31 PM
Subject: Re: [FlyRotary] Re: Return to=20 Flight

 

I agree with Bobby, this may (hopefully) be the= cause,=20 but if so it just means that you didn't design in an adequate way to= fill=20 the coolant without trapping air.  You would hate to have to do= a=20 coolant-prep flight every time you wanted to drain and refill the cool= ant.=20 (but not the end of the world).

 

I originally designed my system like Ed's. = Minimal=20 drag (just the 2 stock RV-6 inlets) but cooling was like you and Ed=20 describe...  OK, but you always have to keep and eye on it and of= ten=20 reduce power or AOA in order to keep coolant temps in check.  The= n I=20 made a major change to provide TONS of air to an adequately sized=20 radiator.  Since,  I never even think about cooling. = Yes, I=20 do probably burn a little more fuel but it is well worth it to never= worry=20 about cooling again.  Its not rocket science.  Adequate air= to an=20 adequate radiator equals adequate cooling.  Change adequate to pl= enty=20 in that sentence and now your are rocking!

 

Dave Leonard

 

On Mon, May 4, 2015 at 12:37 PM, Bobby J. Hughes= <flyrotary@lancaironline.net> wrote:<= /P>

Jeff,

 

Congratulations on getting back in the air.= That =C2=BD=20 quart of coolant may have been trapped air that purged during flight.= =20

 

Bobby Hughes

N416AS-

RV10  223 hrs

 

From: Rotary= motors=20 in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Mond= ay, May=20 04, 2015 7:53 AM
To: Rotary motors in aircraft
Subject= :=20 [FlyRotary] Return to Flight

 =

Yester= day=20 3-May, my bird got airborne once again on its maiden flight after 2+= years=20 rebuilding.  I had a friend test-pilot fly it while I was flight= =20 engineer watching the gauges.  Flight controls and rigging were= =20 reported to be good and the engine performed flawlessly.  The oil= =20 temperature was stable around 160F (Mazda oil cooler in series with a= =20 Fluidyne) but again the water temperature was high reaching 210F by ci= rcuit=20 height so we backed off the throttle, did a touch and go with a 500=E2= =80=99 circuit=20 and parked it.  One unusual result was the cooling system pressur= e was=20 only at 5-6 psi; with the high temperature it should have been 15-16= =20 psi.  Removed the cowlings and found no leaks of either oil or=20 glycol.  I checked the coolant level and it was down, requiring= 1/2=20 quart to top it up. I also looked at my pinched duct and think it need= s more=20 pinching, so am already starting to modify that =E2=80=93 hope to get= another test=20 flight in before the weekend.

 =

Jeff

This= message,=20 and the documents attached hereto, is intended only for the addressee= and=20 may contain privileged or confidential information. Any unauthorized= =20 disclosure is strictly prohibited. If you have received this message= in=20 error, please notify us immediately so that we may correct our interna= l=20 records. Please then delete the original message. Thank you.=20

 

This message, an= d the=20 documents attached hereto, is intended only for the addressee and may= =20 contain privileged or confidential information. Any unauthorized discl= osure=20 is strictly prohibited. If you have received this message in error, pl= ease=20 notify us immediately so that we may correct our internal records. Ple= ase=20 then delete the original message. Thank you.=20
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