X-Virus-Scanned: clean according to Sophos on Logan.com From: "Al Wick" Received: from outbound-mail02.dca.untd.com ([64.136.47.36] verified) by logan.com (CommuniGate Pro SMTP 6.1.2) with SMTP id 7675952 for flyrotary@lancaironline.net; Wed, 06 May 2015 11:16:04 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.47.36; envelope-from=alwick@juno.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=juno.com; s=alpha; t=1430925330; bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=; l=0; h=Message-ID:From:To:Subject:Date:Content-Type; b=pX9XnDkQEFjBtjV3lywlhOrmUTRrppfMw1Vafz2YTxPdp4n+yQzTpfNXgnCjlshDC EStIRoBlySIlsI/8Ukh5FDgTXdyBp+0dyJ1rGkgnPsX0J952P7ZE8pxQfvMq9b8fa2 GS03PcCFWk2qYfwTwUQQf8XBrZ7mEAIzFFBnnhAM= Received: from Admin7PC ([172.79.89.229]) by smtpout04.dca.untd.com with SMTP id AABLWWNARAY4L6FJ for (sender ); Wed, 6 May 2015 08:15:27 -0700 (PDT) Message-ID: To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Return to Flight Date: Wed, 6 May 2015 08:15:19 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_004B_01D087D4.CAA79060" 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: 172.79.89.229 X-UNTD-BodySize: 19974 X-ContentStamp: 42:21:2101700565 X-MAIL-INFO:26cd9d19cd65fd64101965c9c91054d03494906de0a0d5f4dd59c58474b9d114e9f4417d7d0c6101000021111125114d20404595959de519ad0559101595d9c00149752d49d92509d90c2124b149690c492d99d5d4d56db5e0a00c30b491e1c109450950293d35705495b5a4f9f9a11ddd91ad14246d X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkPX7N4LjjLZNAjBxQwn83iWg5lmVWvioSg== X-UNTD-Peer-Info: 10.171.42.34|smtpout04.dca.untd.com|smtpout04.dca.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_004B_01D087D4.CAA79060 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Jeff. I=E2=80=99ve done lot=E2=80=99s of experimenting with cooling = sys. Tough to 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 = in the system. If you=E2=80=99d taken off with 2 cups of air, then = pressure would have been 9 psi. 1 cup, 14 psi. No air in system, then = you would have seen rated cap pressure (16 psi in your case).=20 Sorry to say, the pressure you see has no significant effect on cooling = efficiency (heat transfer). The next time you fly, since you=E2=80=99ve = removed most of that air, you will still see 210F. Just like before. = There=E2=80=99s one huge exception to that statement, that=E2=80=99s if = you have air in sys that can=E2=80=99t move to a high point out of the = flow. In that case air in sys has huge negative effect. Causes local = boiling when it passes hot areas and inflates cooling temp.=20 You don=E2=80=99t have to fly to prove these concepts. Ground running at = idle is all that=E2=80=99s needed. Let=E2=80=99s assume all air is = removed. Then letting engine warm up to 180 F will result in rapid = pressure rise to 16 psi (rated cap pressure). Fluid will exit system. = With 2 cups of air in sys, that same 180F will yield slow rise in = pressure to only 9 psi. No fluid will leave sys.=20 A good cooling design pretends air is stuck in block, so you add a path = for that air to rise out of the block coolant flow. This is called a = dynamic bleed. Air is automatically removed from engine coolant flow. = Super low risk way to fly as you no longer care if air is in system. = It=E2=80=99s can=E2=80=99t affect cooling.=20 It=E2=80=99s a bit higher risk to fly without dynamic air bleed, you = just make darn sure you purge all air from block sys prior to flight. = Applying vacuum to rad cap is great way to remove air.=20 One of the ironies about cooling design is that air that resides above = engine flow is a safety asset. For example, your cap is highest point in = sys and you have 2 cups of air under cap. Big safety advantage simply = because your pressure gage is then a great predictor of how well your = sys is doing. A leak will be detected long before overheating. A bunch = of other assets to this design.=20 Conversely, air in engine flow has overwhelming negative affect. Temps = soar and risks boil over.=20 Clear as mud eh? Fwiw -al wick From: Jeff Whaley=20 Sent: Wednesday, May 06, 2015 4:54 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Return to Flight Dave, I can=E2=80=99t argue with your adequate theory; I have that for = my oil cooling system, along with the temperature-controlled Mazda oil = cooler, I never worry about oil temperature. It=E2=80=99s the practical application of that theory to the radiator = installation that has plagued me from the beginning =E2=80=A6 after the = next flight I=E2=80=99ll know where I stand and if there=E2=80=99s still = a problem, then radical change may have to be the recipe. Jeff =20 From: David Leonard [mailto:flyrotary@lancaironline.net]=20 Sent: Tuesday, May 05, 2015 9:31 PM Subject: Re: [FlyRotary] Re: Return to Flight =20 I agree with Bobby, this may (hopefully) be the cause, but if so it just = means that you didn't design in an adequate way to fill the coolant = without trapping air. You would hate to have to do a coolant-prep = flight every time you wanted to drain and refill the coolant. (but not = the end of the world). =20 I originally designed my system like Ed's. Minimal drag (just the 2 = stock RV-6 inlets) but cooling was like you and Ed describe... OK, but = you always have to keep and eye on it and often reduce power or AOA in = order to keep coolant temps in check. Then I made a major change to = provide TONS of air to an adequately sized radiator. Since, I never = even think about cooling. Yes, I do probably burn a little more fuel = but it is well worth it to never worry about cooling again. Its not = rocket science. Adequate air to an adequate radiator equals adequate = cooling. Change adequate to plenty in that sentence and now your are = rocking! =20 Dave Leonard =20 On Mon, May 4, 2015 at 12:37 PM, Bobby J. Hughes = 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_004B_01D087D4.CAA79060 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
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 in=20 the system. If you=E2=80=99d taken off with 2 cups of air, then pressure = would have been=20 9 psi. 1 cup, 14 psi. No air in system, then you would have seen rated = cap=20 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 of=20 that air, you will still see 210F. Just like before. There=E2=80=99s one = huge exception=20 to that statement, that=E2=80=99s if you have air in sys that = can=E2=80=99t move to a high point=20 out of the flow. In that case air in sys has huge negative effect. = Causes local=20 boiling when it passes hot areas and inflates cooling 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 up=20 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 for=20 that air to rise out of the block coolant flow. This is called a dynamic = bleed.=20 Air is automatically removed from engine coolant flow. Super low risk = way to fly=20 as you no longer care if air is in system. It=E2=80=99s can=E2=80=99t = affect cooling.
 
It=E2=80=99s a bit higher risk to fly without dynamic air bleed, = you just make darn=20 sure you purge all air from block sys prior to flight. Applying vacuum = to rad=20 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 and=20 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 soar=20 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 system,=20 along with the temperature-controlled Mazda oil cooler, I never worry = about oil=20 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 9:31=20 PM
Subject: Re: [FlyRotary] Re: Return to=20 Flight

 

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

 

I originally designed my system like Ed's.  = Minimal drag=20 (just the 2 stock RV-6 inlets) but cooling was like you and Ed = describe... =20 OK, but you always have to keep and eye on it and often reduce power or = AOA in=20 order to keep coolant temps in check.  Then I made a major change = to=20 provide TONS of air to an adequately sized radiator.  Since,  = I never=20 even think about cooling.  Yes, I do probably burn a little more = fuel but=20 it is well worth it to never worry about cooling again.  Its not = rocket=20 science.  Adequate air to an adequate radiator equals adequate=20 cooling.  Change adequate to plenty in that sentence and now your = are=20 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 quart=20 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 04,=20 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 good=20 and the engine performed flawlessly.  The oil temperature was = stable around=20 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 it=20 was down, requiring 1/2 quart to top it up. I also looked at my pinched = duct and=20 think it needs more pinching, so am already starting to modify that = =E2=80=93 hope to=20 get another test flight in before the weekend.

 

Jeff

This = message, and=20 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=20 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=20 original message. Thank you. ------=_NextPart_000_004B_01D087D4.CAA79060--