X-Virus-Scanned: clean according to Sophos on Logan.com From: "Al Wick" Received: from outbound-mail02.vgs.untd.com ([64.136.55.36] verified) by logan.com (CommuniGate Pro SMTP 6.1.2) with SMTP id 7680129 for flyrotary@lancaironline.net; Fri, 08 May 2015 09:46:46 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.55.36; envelope-from=alwick@juno.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=juno.com; s=alpha; t=1431092771; bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=; l=0; h=Message-ID:From:To:Subject:Date:Content-Type; b=FRrwmZypD7BO3ukOEJiiz0+bnjFF+d1H6nrH8YNnsjiYZ6DztU0Wzj0wehFGivKAs kww1C2LDyji6ecpymLxGnhhtSL4aiEmagu3fMDN9xBOaGNsx3eh047Z+bl4XExEarI 7JT2XZ9LwHApyyLh17aKH2lcB/0saDICNmsmSAaQ= Received: from Admin7PC ([50.38.123.215]) by smtpout02.vgs.untd.com with SMTP id AABLW3RSNAKMK3JJ for (sender ); Fri, 8 May 2015 06:45:48 -0700 (PDT) Message-ID: To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Return to Flight Date: Fri, 8 May 2015 06:45:46 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_005A_01D0895A.9CF94C30" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 16.4.3528.331 X-MimeOLE: Produced By Microsoft MimeOLE V16.4.3528.331 X-Originating-Ip: 50.38.123.215 X-UNTD-BodySize: 30261 X-ContentStamp: 72:36:661105734 X-MAIL-INFO:4d7e339ac38beea30b275b27e7bb8e6b6ec7170fb3d7d77acefeee377beb03 X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkIHOt/vPqJiBV5kiBSzoCplbcTWE6G/M5A== X-UNTD-Peer-Info: 10.181.42.32|smtpout02.vgs.untd.com|smtpout02.vgs.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_005A_01D0895A.9CF94C30 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable wrote: Jeff, =20 Congratulations on getting back in the air. That =C2=BD quart of = coolant may have been trapped air that purged during flight.=20 =20 Bobby Hughes N416AS-=20 RV10 223 hrs =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]=20 Sent: Monday, May 04, 2015 7:53 AM To: Rotary motors in aircraft Subject: [FlyRotary] Return to Flight =20 Yesterday 3-May, my bird got airborne once again on its maiden flight = after 2+ years rebuilding. I had a friend test-pilot fly it while I was = flight engineer watching the gauges. Flight controls and rigging were = reported to be good and the engine performed flawlessly. The oil = temperature was stable around 160F (Mazda oil cooler in series with a = Fluidyne) but again the water temperature was high reaching 210F by = circuit height so we backed off the throttle, did a touch and go with a = 500=E2=80=99 circuit and parked it. One unusual result was the cooling = system pressure was only at 5-6 psi; with the high temperature it should = have been 15-16 psi. Removed the cowlings and found no leaks of either = oil or glycol. I checked the coolant level and it was down, requiring = 1/2 quart to top it up. I also looked at my pinched duct and think it = needs more pinching, so am already starting to modify that =E2=80=93 = hope to get another test flight in before the weekend. =20 Jeff This message, and the documents attached hereto, is intended only for = the addressee and may contain privileged or confidential information. = Any unauthorized disclosure is strictly prohibited. If you have received = this message in error, please notify us immediately so that we may = correct our internal records. Please then delete the original message. = Thank you.=20 =20 This message, and the documents attached hereto, is intended only for = the addressee and may contain privileged or confidential information. = Any unauthorized disclosure is strictly prohibited. If you have received = this message in error, please notify us immediately so that we may = correct our internal records. Please then delete the original message. = Thank you. ------=_NextPart_000_005A_01D0895A.9CF94C30 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
<I am a = little confused=20 about the system pressure being able to read what the pressure cap = setting 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 this=20 time, remove 2 cups of fluid. This time when you warm up engine, you see = max=20 pressure of 10 psi. No fluid will overflow. This is because that two = cups of air=20 acts like a giant spring. Air molecules are far apart and easily = compress.=20
 
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 = number of=20 common problems, but the two cup of air method makes all the problems = clear with=20 gobs of advance notice. For example, I was deliberately very abusive to = my first=20 engine. Overheated it time and again during ground run experiments. = Suddenly I=20 saw 22 psi, where normally it never exceeds 12 psi. That pressure only = lasted=20 for 5 seconds. Sure nuff, I review the data, this was caused by my = finally=20 getting a compression leak into cooling sys. It only leaked for 5 = seconds after=20 applying full throttle. Would not have been able to observe this if I = had a=20 fully filled cooling sys. 
 
<are you = using an=20 unpressurized reservoir
 
Not needed with two cup of air sys. = Coolant 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 = protection.=20 Boil over is a big deal. When it happens it=E2=80=99s darn near = irreversible. Pretty=20 remarkable actually. You reduce power and it continues to boil fluid out = of=20 system. I use 22 psi cap. With my 50/50 mix, that means boil over = can=E2=80=99t occur=20 until I reach a whopping 289F. 16 psi cap is a good choice. That would = boil over=20 at 252 F and you are not running at needlessly high 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 = that I achieve=20 very high operating temp. If I reach 289F, then my 2 cups of air are = fully=20 compressed. I would then have completely fluid filled sys that needs to = dump=20 water to prevent rad from blowing open.
 
-al wick
 
 
From: ARGOLDMAN
Sent: Wednesday, May 06, 2015 11:25 AM
Subject: [FlyRotary] Re: Return to Flight
 
Interesting discussion, Al.
 
I am a little confused about the system pressure being able to read = what=20 the pressure cap setting is, and somehow adjusting the pressure, under = normal=20 operating conditions.
 
My understanding and evaluation of the mechanics of the cap is that = If and=20 only if the system pressure exceeds the cap setting,coolant is blown = overboard=20 or into the reservoir until pressure goes down to the setting and then = that=20 stops. It seems to be, in effect, a popoff safety valve and not a=20 controller.
 
In the above (below) example, are you using an unpressurized = reservoir=20 (such as is used in automotive applications) or an air buffer at the top = of a=20 sealed cooling system, or both.
 
Other than with extreme temperature and the ability to blow off = coolant=20 with high pressure, due to this excessive temperature, to prevent = blowing off=20 hoses and gaskets (and in our case seals), what is the purpose of the = cap's=20 setting assuming that it is rated above, (if only slightly) normal = operating=20 pressure.(assuming the setting is high enough to allow the pressure = created by=20 the normal expansion of the fluid as it heats? )
 
Would it not be true that in an "Ideal" system that a popoff cap = would=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 = cooling 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 air=20 in the system. If you=E2=80=99d taken off with 2 cups of air, then = pressure would have=20 been 9 psi. 1 cup, 14 psi. No air in system, then you would have seen = rated=20 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=99ve removed most=20 of that air, you will still see 210F. Just like before. = There=E2=80=99s one huge=20 exception to that statement, that=E2=80=99s if you have air in sys = that can=E2=80=99t move to=20 a high point out of the flow. In that case air in sys has huge = negative=20 effect. Causes local boiling when it passes hot areas and inflates = cooling=20 temp.
 
You don=E2=80=99t have to fly to prove these concepts. Ground = running at idle is=20 all that=E2=80=99s needed. Let=E2=80=99s assume all air is removed. = Then letting engine warm=20 up to 180 F will result in rapid pressure rise to 16 psi (rated cap = pressure).=20 Fluid will exit system. With 2 cups of air in sys, that same 180F will = yield=20 slow rise in pressure to only 9 psi. No fluid will leave sys.
 
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 = low 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 to=20 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 = because your=20 pressure gage is then a great predictor of how well your sys is doing. = A leak=20 will be detected long before overheating. A bunch of other assets to = this=20 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
Sent: Wednesday, May 06, 2015 4:54 AM
Subject: [FlyRotary] Re: Return to = Flight
 

Dave,=20 I can=E2=80=99t argue with your adequate theory; I have that for my = oil cooling=20 system, along with the temperature-controlled Mazda oil cooler, I = never worry=20 about oil temperature.

It=E2=80=99s=20 the practical application of that theory to the radiator installation = that has=20 plagued me from the beginning =E2=80=A6 after the next flight = I=E2=80=99ll know where I stand=20 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, but=20 if so it just means that you didn't design in an adequate way to fill = the=20 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 = coolant.=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 = often=20 reduce power or AOA in order to keep coolant temps in check.  = Then I made=20 a major change to provide TONS of air to an adequately sized = radiator. =20 Since,  I never even think about cooling.  Yes, I do = probably burn a=20 little more fuel but it is well worth it to never worry about cooling=20 again.  Its not rocket science.  Adequate air to an adequate = radiator equals adequate cooling.  Change adequate to plenty in = that=20 sentence and now your are rocking!

 

Dave Leonard

 

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

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

 

Yesterday 3-May,=20 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 = engineer=20 watching the gauges.  Flight controls and rigging were reported = to be=20 good and the engine performed flawlessly.  The oil temperature = was stable=20 around 160F (Mazda oil cooler in series with a Fluidyne) but again the = water=20 temperature was high reaching 210F by circuit height so we backed off = the=20 throttle, did a touch and go with a 500=E2=80=99 circuit and parked = it.  One=20 unusual result was the cooling system pressure was only at 5-6 psi; = with the=20 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 = pinched=20 duct and think it needs more pinching, so am already starting to = modify that =E2=80=93=20 hope to get another test flight in before the weekend.

 

Jeff

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

 

This message, = and the=20 documents attached hereto, is intended only for the addressee and may = contain=20 privileged or confidential information. Any unauthorized disclosure is = strictly prohibited. If you have received this message in error, = please notify=20 us immediately so that we may correct our internal records. Please = then delete=20 the original message. Thank you.=20 ------=_NextPart_000_005A_01D0895A.9CF94C30--