X-Virus-Scanned: clean according to Sophos on Logan.com From: Received: from resqmta-ch2-03v.sys.comcast.net ([69.252.207.35] verified) by logan.com (CommuniGate Pro SMTP 6.1.2) with ESMTPS id 7693945 for flyrotary@lancaironline.net; Fri, 15 May 2015 13:44:38 -0400 Received-SPF: pass receiver=logan.com; client-ip=69.252.207.35; envelope-from=hoursaway1@comcast.net Received: from resomta-ch2-05v.sys.comcast.net ([69.252.207.101]) by resqmta-ch2-03v.sys.comcast.net with comcast id UHja1q0032Bo0NV01Hk2hJ; Fri, 15 May 2015 17:44:02 +0000 Received: from resmail-ch2-632v.sys.comcast.net ([162.150.50.156]) by resomta-ch2-05v.sys.comcast.net with comcast id UHk21q00G3NCDde01Hk2NZ; Fri, 15 May 2015 17:44:02 +0000 Date: Fri, 15 May 2015 17:44:02 +0000 (UTC) To: "Fly rotary blog, e-mail" Message-ID: <1841830027.7092651.1431711842064.JavaMail.zimbra@comcast.net> In-Reply-To: References: Subject: Re: [FlyRotary] Return to Flight - 2 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_7092650_2040008226.1431711842063" X-Originating-IP: [::ffff:24.127.211.224] X-Mailer: Zimbra 8.0.7_GA_6031 (ZimbraWebClient - IE7 (Win)/8.0.7_GA_6031) Thread-Topic: Return to Flight - 2 Thread-Index: x6W+M9OtDYppbMeJehyL0jnzdgt8fg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1431711842; bh=XgX1IUZ0by2V9W6OBDgPNWc4cDB6nZtrxVrQfCzVF7o=; h=Received:Received:Date:From:To:Message-ID:Subject:MIME-Version: Content-Type; b=pFa6V6FP6Ws2hF7nq82GP2OLyE21BhBoR6IVkMKeqjkQuT5X9WUmvumaPUbt8nJyb pIagwG6hFh5my7ZPJ8NHCuNcCE8Y7236JarAIYy3nd5NprXTFJ6nzLdBdXNyrTObP4 Eqb0rMgQMljXPpWiarXXJR2QriZiKqQkOcYB/8MR/kIZUVw7iVtkAwg4Xe6LRyCion TLH3w1G0gACPWZG11t2Ji+ojSEZKz7JuyRst25SmZ03anfxbNV6oZD3EFM6mYdEDVe 5IK4M0VsPrBfB+X/hJpFHx9mzFyEyvzi5J0A3v3XuaulKjbA2dAl61YKKfB7Zvm+yJ DRt/D+dlRgSCQ== ------=_Part_7092650_2040008226.1431711842063 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable #2 INCREASE OUTLET AREA, we did that & cured our problem, added aprox. 16" = square at bottom of cowl on both sides (32" total) RV6A Rotary. David R. Co= ok=C2=A0 RV6A Rotary. will look for pic. tonight.=C2=A0=20 ----- Original Message ----- From: "Jeff Whaley" =20 To: "Rotary motors in aircraft" =20 Sent: Friday, May 15, 2015 11:19:24 AM=20 Subject: [FlyRotary] Return to Flight - 2=20 Well, the second flight occurred last night with same results as before; on= e short low-level circuit due to insufficient cooling =E2=80=A6 looks like = Al Wick made the correct prediction.=20 There are 3 things I can try with the current configuration: 1) Increase in= let area 2) Increase outlet area (adjustable cowl flap) 3) Re-profile the p= inched diffuser.=C2=A0 I will do all 3 and see what happens.=20 If all of the above show remarkable improvement then repositioning the radi= ator is the only alternative.=20 Jeff=20 =C2=A0=20 From: Bobby J. Hughes [mailto:flyrotary@lancaironline.net]=20 Sent: Wednesday, May 06, 2015 12:36 PM=20 Subject: RE: [FlyRotary] Re: Return to Flight=20 =C2=A0=20 Al,=20 =C2=A0=20 =E2=80=9CSorry to say, the pressure you see has no significant effect on co= oling efficiency (heat transfer). The next time you fly, since you=E2=80=99= ve removed most of that air, you will still see 210F. Just like before=E2= =80=9D.=20 =C2=A0=20 If the air was trapped at the top of the heat exchanger I would expect impr= oved temperatures. Could be wrong.=20 =C2=A0=20 Bobby Hughes=20 =C2=A0=20 =C2=A0=20 =C2=A0=20 From: Rotary motors in aircraft [ mailto:flyrotary@lancaironline.net ]=20 Sent: Wednesday, May 06, 2015 11:15 AM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Return to Flight=20 =C2=A0=20 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:=20 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 w= ould 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 =C2=A0=20 Sorry to say, the pressure you see has no significant effect on cooling eff= iciency (heat transfer). The next time you fly, since you=E2=80=99ve remove= d 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 i= n 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 h= ot areas and inflates cooling temp.=20 =C2=A0=20 You don=E2=80=99t have to fly to prove these concepts. Ground running at id= le is all that=E2=80=99s needed. Let=E2=80=99s assume all air is removed. T= hen letting engine warm up to 180 F will result in rapid pressure rise to 1= 6 psi (rated cap pressure). Fluid will exit system. With 2 cups of air in s= ys, that same 180F will yield slow rise in pressure to only 9 psi. No fluid= will leave sys.=20 =C2=A0=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 b= leed. 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 =C2=A0=20 It=E2=80=99s a bit higher risk to fly without dynamic air bleed, you just m= ake darn sure you purge all air from block sys prior to flight. Applying va= cuum to rad cap is great way to remove air.=20 =C2=A0=20 One of the ironies about cooling design is that air that resides above engi= ne flow is a safety asset. For example, your cap is highest point in sys an= d you have 2 cups of air under cap. Big safety advantage simply because you= r 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 t= his design.=20 =C2=A0=20 Conversely, air in engine flow has overwhelming negative affect. Temps soar= and risks boil over.=20 =C2=A0=20 Clear as mud eh?=20 =C2=A0=20 Fwiw=20 =C2=A0=20 -al wick=20 =C2=A0=20 This message, and the documents attached hereto, is intended only for the a= ddressee and may contain privileged or confidential information. Any unauth= orized 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 ------=_Part_7092650_2040008226.1431711842063 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
#2 INCREASE OUTLET AREA, we did that &= amp; cured our problem, added aprox. 16" square at bottom of cowl on both s= ides (32" total) RV6A Rotary. David R. Cook  RV6A Rotary. will look fo= r pic. tonight. 

From: "Jeff Whaley" <flyrotary@lancaironline.net>
To:= "Rotary motors in aircraft" <flyrotary@lancaironline.net>
= Sent: Friday, May 15, 2015 11:19:24 AM
Subject: [FlyRotary] R= eturn to Flight - 2

Well, the second flight occu= rred last night with same results as before; one short low-level circuit du= e to insufficient cooling =E2=80=A6 looks like Al Wick made the correct pre= diction.

There are 3 things I can try= with the current configuration: 1) Increase inlet area 2) Increase outlet = area (adjustable cowl flap) 3) Re-profile the pinched diffuser.  I wil= l do all 3 and see what happens.

If all of the above show rem= arkable improvement then repositioning the radiator is the only alternative= .

Jeff

 

From: Bobby J. Hughes [mailto:flyrotary@lancaironline.ne= t]
Sent: Wednesday, May 06, 2015 12:36 PM
Subject: RE:= [FlyRotary] Re: Return to Flight

 

Al,

 

=E2=80=9CSorry to say, the pressure you see has no significant effec= t 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 be= fore=E2=80=9D.

 

If the air was trapped at the top of the heat exchanger I would expe= ct improved temperatures. Could be wrong.

 

Bobby Hughes

 

 

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: = Wednesday, May 06, 2015 11:15 AM
To: Rotary motors in aircraftSubject: [FlyRotary] Re: Return to Flight

 

Hi Jeff. I=E2=80=99ve done lot=E2=80=99s of experimenting with cooli= ng 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 pre= ssure would have been 9 psi. 1 cup, 14 psi. No air in system, then you woul= d have seen rated cap pressure (16 psi in your case).

 

Sorry to say, the pressure you see has no significant effect on cool= ing 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 tha= t case air in sys has huge negative effect. Causes local boiling when it pa= sses hot areas and inflates cooling temp.

 

You don=E2=80=99t have to fly to prove these concepts. Ground runnin= g at idle is all that=E2=80=99s needed. Let=E2=80=99s assume all air is rem= oved. Then letting engine warm up to 180 F will result in rapid pressure ri= se to 16 psi (rated cap pressure). Fluid will exit system. With 2 cups of a= ir in sys, that same 180F will yield slow rise in pressure to only 9 psi. N= o fluid will leave sys.

 

A good cooling design pretends air is stuck in block, so you add a p= ath for that air to rise out of the block coolant flow. This is called a dy= namic bleed. Air is automatically removed from engine coolant flow. Super l= ow risk way to fly 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 sure you purge all air from block sys prior to flight. Appl= ying vacuum to rad cap is great way to remove air.

 

One of the ironies about cooling design is that air that resides abo= ve 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 beca= use your pressure gage is then a great predictor of how well your sys is do= ing. A leak will be detected long before overheating. A bunch of other asse= ts to this design.

 

Conversely, air in engine flow has overwhelming negative affect. Tem= ps soar and risks boil over.

 

Clear as mud eh?

 

Fwiw

 

-al wick

 

This message, and the docum= ents attached hereto, is intended only for the addressee and may contain pr= ivileged or confidential information. Any unauthorized disclosure is strict= ly prohibited. If you have received this message in error, please notify us= immediately so that we may correct our internal records. Please then delet= e the original message. Thank you.

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