X-Virus-Scanned: clean according to Sophos on Logan.com From: Received: from omr-m08.mx.aol.com ([64.12.222.129] verified) by logan.com (CommuniGate Pro SMTP 6.1.2) with ESMTPS id 7676485 for flyrotary@lancaironline.net; Wed, 06 May 2015 14:26:22 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.222.129; envelope-from=ARGOLDMAN@aol.com Received: from mtaomg-aal01.mx.aol.com (mtaomg-aal01.mx.aol.com [172.27.20.207]) by omr-m08.mx.aol.com (Outbound Mail Relay) with ESMTP id E0B18704CE219 for ; Wed, 6 May 2015 14:25:48 -0400 (EDT) Received: from core-aba04b.mail.aol.com (core-aba04.mail.aol.com [172.27.22.4]) by mtaomg-aal01.mx.aol.com (OMAG/Core Interface) with ESMTP id A5DA338000088 for ; Wed, 6 May 2015 14:25:48 -0400 (EDT) Full-name: ARGOLDMAN Message-ID: <90ed9.3b795d38.427bb6ac@aol.com> Date: Wed, 6 May 2015 14:25:48 -0400 Subject: Re: [FlyRotary] Re: Return to Flight To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_90ed9.3b795d38.427bb6ac_boundary" X-Mailer: AOL 9.7 sub 3044 X-Originating-IP: [50.151.84.101] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20140625; t=1430936748; bh=cgdQ+mOhgYxTu5U0ZiewxsAcxXOUBzKMenIjwITgEeU=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=kgQCxT3/jHpSuN7u7Urm96f4/UMvjc70DjW0Znw9bNeSGlRumerZ0iD0/d8olrabp xlv0DoOKv8z44egV2GrM8yNbiF592Vm1Lp3XcS5/rS9lRY4tuQ2TMtrsYzxUDzTm+K 5eVJC/DC8D2r9O48SgGSXhr7so+V6eZr5ILlY+88= x-aol-sid: 3039ac1b14cf554a5cac63df --part1_90ed9.3b795d38.427bb6ac_boundary Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en Interesting discussion, Al. =20 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 nor= mal=20 operating conditions. =20 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 =20 overboard or into the reservoir until pressure goes down to the setting an= d then =20 that stops. It seems to be, in effect, a popoff safety valve and not a =20 controller. =20 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. =20 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=20 cap's setting assuming that it is rated above, (if only slightly) normal= =20 operating pressure.(assuming the setting is high enough to allow the pres= sure=20 created by the normal expansion of the fluid as it heats? ) =20 Would it not be true that in an "Ideal" system that a popoff cap would =20 theoretically not be necessary? =20 Thanks for your input =20 Rich =20 =20 In a message dated 5/6/2015 10:16:33 A.M. Central Daylight Time, =20 flyrotary@lancaironline.net writes: =20 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 pressur= e would=20 have been 9 psi. 1 cup, 14 psi. No air in system, then you would have see= n=20 rated cap pressure (16 psi in your case).=20 =20 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 re= moved most =20 of that air, you will still see 210F. Just like before. There=E2=80=99s on= e huge =20 exception to that statement, that=E2=80=99s if you have air in sys that ca= n=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.=20 =20 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=20 pressure). Fluid will exit system. With 2 cups of air in sys, that same= 180F will=20 yield slow rise in pressure to only 9 psi. No fluid will leave sys.=20 =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 dynam= ic =20 bleed. Air is automatically removed from engine coolant flow. Super low ri= sk=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.=20 =20 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 vacuu= m to =20 rad cap is great way to remove air.=20 =20 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= =20 your pressure gage is then a great predictor of how well your sys is doin= g. A=20 leak will be detected long before overheating. A bunch of other assets to= =20 this design.=20 =20 Conversely, air in engine flow has overwhelming negative affect. Temps =20 soar and risks boil over.=20 =20 Clear as mud eh? =20 Fwiw =20 -al wick =20 =20 =20 From: _Jeff Whaley_ (mailto:flyrotary@lancaironline.net) =20 =20 =20 Sent: Wednesday, May 06, 2015 4:54 AM To: _Rotary motors in aircraft_ (mailto:flyrotary@lancaironline.net) =20 Subject: [FlyRotary] Re: Return to Flight =20 =20 =20 Dave, I can=E2=80=99t argue with your adequate theory; I have that for my= oil=20 cooling system, along with the temperature-controlled Mazda oil cooler,= I never=20 worry about oil temperature.=20 It=E2=80=99s the practical application of that theory to the radiator ins= tallation=20 that has plagued me from the beginning =E2=80=A6 after the next flight I= =E2=80=99ll know=20 where I stand and if there=E2=80=99s still a problem, then radical change= may have=20 to be the recipe.=20 Jeff=20 =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= =20 means that you didn't design in an adequate way to fill the coolant witho= ut=20 trapping air. You would hate to have to do a coolant-prep flight every= =20 time you wanted to drain and refill the coolant. (but not the end of the= =20 world).=20 =20 =20 I originally designed my system like Ed's. Minimal drag (just the 2 stoc= k=20 RV-6 inlets) but cooling was like you and Ed describe... OK, but you=20 always have to keep and eye on it and often reduce power or AOA in order= to=20 keep coolant temps in check. Then I made a major change to provide TONS= of=20 air to an adequately sized radiator. Since, I never even think about=20 cooling. Yes, I do probably burn a little more fuel but it is well worth= it to=20 never worry about cooling again. Its not rocket science. Adequate air= to=20 an adequate radiator equals adequate cooling. Change adequate to plenty= in=20 that sentence and now your are rocking! =20 =20 Dave Leonard =20 =20 On Mon, May 4, 2015 at 12:37 PM, Bobby J. Hughes=20 <_flyrotary@lancaironline.net_ (mailto:flyrotary@lancaironline.net) > 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= off=20 the 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 th= at =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_90ed9.3b795d38.427bb6ac_boundary Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
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 nor= mal=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=20 overboard or into the reservoir until pressure goes down to the setting an= d then=20 that 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 reservoi= r=20 (such as is used in automotive applications) or an air buffer at= the=20 top of a sealed cooling system, or both.
 
Other than with extreme temperature and the ability to blow off coola= nt=20 with high pressure, due to this excessive temperature, to preven= t=20 blowing off hoses and gaskets (and in our case seals), what is the purpose= of=20 the cap's setting assuming that it is rated above, (if only=20 slightly) normal operating pressure.(assuming the setting&n= bsp;is=20 high enough to allow the pressure created by the normal expansion of the= fluid=20 as it heats? )
 
Would it not be true that in an "Ideal" system that a popoff cap woul= d=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 cool= ing 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 press= ure would have=20 been 9 psi. 1 cup, 14 psi. No air in system, then you would have seen ra= ted=20 cap pressure (16 psi in your case).
 
Sorry to say, the pressure you see has no significant effect on coo= ling=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 cooli= ng=20 temp.
 
You don=E2=80=99t have to fly to prove these concepts. Ground runni= ng 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 pres= sure).=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 dyn= amic=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, yo= u just make=20 darn sure you purge all air from block sys prior to flight. Applying vac= uum to=20 rad cap is great way to remove air.
 
One of the ironies about cooling design is that air that resides ab= ove=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 becaus= e 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 thi= s=20 design.
 
Conversely, air in engine flow has overwhelming negative affect. Te= mps=20 soar and risks boil over.
 
Clear as mud eh?
 
Fwiw
 
-al wick
 
 
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 th= at has=20 plagued me from the beginning =E2=80=A6 after the next flight I=E2=80=99= ll 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 Leo= nard=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 cau= se, but=20 if so it just means that you didn't design in an adequate way to fill th= e=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 coolan= t.=20 (but not the end of the world).

 

I originally designed my system like Ed's.  Mi= nimal=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 ofte= n=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.&n= bsp;=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= =20 radiator equals adequate cooling.  Change adequate to plenty in tha= t=20 sentence and now your are rocking!

 

Dave Leonard

 

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

Jeff,

 

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

 

Bobby Hughes

N416AS-

RV10  223 hrs

 

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

 

Yesterda= y 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 en= gineer=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 th= e=20 throttle, did a touch and go with a 500=E2=80=99 circuit and parked it.&= nbsp; 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 cowlin= gs and=20 found no leaks of either oil or glycol.  I checked the coolant leve= l and=20 it was down, requiring 1/2 quart to top it up. I also looked at my pinch= ed=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 mes= sage,=20 and the documents attached hereto, is intended only for the addressee an= d may=20 contain privileged or confidential information. Any unauthorized disclos= ure 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 co= ntain=20 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.=20 --part1_90ed9.3b795d38.427bb6ac_boundary--