X-Virus-Scanned: clean according to Sophos on Logan.com From: "Mark Steitle" Received: from mail-ob0-f175.google.com ([209.85.214.175] verified) by logan.com (CommuniGate Pro SMTP 6.1.2) with ESMTPS id 7694064 for flyrotary@lancaironline.net; Fri, 15 May 2015 14:23:33 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.175; envelope-from=msdstx@gmail.com Received: by obfe9 with SMTP id e9so83964541obf.1 for ; Fri, 15 May 2015 11:22:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:references:from:content-type:in-reply-to:message-id:date:to :content-transfer-encoding:mime-version; bh=fPFMheS/dhTtl4gIP/j2wmGfkUfQl+hrPxrvbl0Fy9o=; b=N+jO4y6TBlhfwZr62BKMvdSgJZvTwsGrLs9UgnHIJZzoXK3nbbPdS5A+W1+LhNLa6v pUBEdF+LGcTk3VksU/r8QDpHviwpRLWzUAyCspMmQl7x2XESFVRgg91piSTNtMDI2utU oiQE5jvDculKT8yKzAG1G5GV13UKCPnhevDwU43dHKk2QG/HCQ6YuvV5GF5TTULDHg+6 iDACrfOjmq0SKkV/oYKAQopwDUMok5X8UsuDlA0ir7bUHT9ZKN35KiMSqgVrW4u8vCzg oYrVNqlvNY5SYrZWk7M1NTkRQieiNwRTlQaRmV5w5JtuBPVGZpSSAG97kXRGq1VIuDOm Ytbw== X-Received: by 10.182.129.19 with SMTP id ns19mr9338559obb.3.1431714177500; Fri, 15 May 2015 11:22:57 -0700 (PDT) Return-Path: Received: from ?IPv6:2602:306:807d:ec60:7c1d:f7de:6a2d:d660? ([2602:306:807d:ec60:7c1d:f7de:6a2d:d660]) by mx.google.com with ESMTPSA id z19sm1253779obp.17.2015.05.15.11.22.55 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 15 May 2015 11:22:56 -0700 (PDT) Subject: Re: [FlyRotary] Return to Flight - 2 References: Content-Type: multipart/alternative; boundary=Apple-Mail-E406C51C-C65A-4906-9555-1D73BE952E36 X-Mailer: iPad Mail (12F69) In-Reply-To: Message-Id: <10E93E81-BAB9-4DBC-9261-79B7AD8FBD0E@gmail.com> Date: Fri, 15 May 2015 13:22:55 -0500 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-E406C51C-C65A-4906-9555-1D73BE952E36 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Jeff, Number 2 did the trick on my 3-rotor installation. I open it on taxi and cli= mb, and then close it for minimal drag in cruise. Btw, I'm using an adjustab= le cowl flap.=20 Mark Sent from my iPad > On May 15, 2015, at 10:19 AM, Jeff Whaley wr= ote: >=20 > Well, the second flight occurred last night with same results as before; o= ne short low-level circuit due to insufficient cooling =E2=80=A6 looks like A= l Wick made the correct prediction. > There are 3 things I can try with the current configuration: 1) Increase i= nlet area 2) Increase outlet area (adjustable cowl flap) 3) Re-profile the p= inched diffuser. I will do all 3 and see what happens. > If all of the above show remarkable improvement then repositioning the rad= iator is the only alternative. > Jeff > =20 > From: Bobby J. Hughes [mailto:flyrotary@lancaironline.net]=20 > Sent: Wednesday, May 06, 2015 12:36 PM > Subject: RE: [FlyRotary] Re: Return to Flight > =20 > Al, > =20 > =E2=80=9CSorry to say, the pressure you see has no significant effect on c= ooling 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 > If the air was trapped at the top of the heat exchanger I would expect imp= roved temperatures. Could be wrong. > =20 > Bobby Hughes > =20 > =20 > =20 > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]=20 > Sent: Wednesday, May 06, 2015 11:15 AM > To: Rotary motors in aircraft > Subject: [FlyRotary] Re: Return to Flight > =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: > Pretty clear you saw 6 psi only because you took off with 3+ cups of air i= n 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 s= een rated cap pressure (16 psi in your case). > =20 > Sorry to say, the pressure you see has no significant effect on cooling ef= ficiency (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=99= s one huge exception to that statement, that=E2=80=99s if you have air in sy= s that can=E2=80=99t move to a high point out of the flow. In that case air i= n sys has huge negative effect. Causes local boiling when it passes hot area= s and inflates cooling temp. > =20 > You don=E2=80=99t have to fly to prove these concepts. Ground running at i= dle 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 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 wi= ll leave sys. > =20 > A good cooling design pretends air is stuck in block, so you add a path fo= r 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 w= ay to fly as you no longer care if air is in system. It=E2=80=99s can=E2=80=99= t affect cooling. > =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 vac= uum to rad cap is great way to remove air. > =20 > One of the ironies about cooling design is that air that resides above eng= ine 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 your= pressure gage is then a great predictor of how well your sys is doing. A le= ak 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 soa= r and risks boil over. > =20 > Clear as mud eh? > =20 > Fwiw > =20 > -al wick > =20 > This message, and the documents attached hereto, is intended only for the a= ddressee and may contain privileged or confidential information. Any unautho= rized disclosure is strictly prohibited. If you have received this message i= n error, please notify us immediately so that we may correct our internal re= cords. Please then delete the original message. Thank you. --Apple-Mail-E406C51C-C65A-4906-9555-1D73BE952E36 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Jeff,

Number 2= did the trick on my 3-rotor installation. I open it on taxi and climb, and t= hen close it for minimal drag in cruise. Btw, I'm using an adjustable cowl f= lap. 

Mark


Sent from my iPad=

On May 15, 2015, at 10:19 AM, Jeff Whaley <flyrotary@lancaironline.net> wrote:

Well, the second flight occ= urred 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 prediction.

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

=

If all of the above show re= markable improvement then repositioning the radiator is the only alternative= .

Jeff

 

From: Bobby J. Hu= ghes [mailto:flyrotary@lancai= ronline.net]
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 ha= s 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=E2=80=9D.

 

If the air was trapped at the top of the heat e= xchanger I would expect improved temperatures. Could be wrong.

 

Bobby Hughes

 

 

 

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

 

Hi Jeff. I=E2=80=99ve done lot=E2=80=99s of ex= perimenting with cooling sys. Tough to explain all this, but I=E2=80=99ll gi= ve it a try:

Pretty clear you saw 6 psi only because you to= ok off with 3+ cups of air in the system. If you=E2=80=99d taken off with 2 c= ups 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 yo= ur case).

 

Sorry to say, the pressure you see has no sign= ificant 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 stat= ement, that=E2=80=99s if you have air in sys that can=E2=80=99t move to a hi= gh point out of the flow. In that case air in sys has huge negative effect. C= auses local boiling when it passes hot areas and inflates cooling temp.

 

You don=E2=80=99t have to fly to prove these c= oncepts. Ground running at idle is all that=E2=80=99s needed. Let=E2=80=99s a= ssume all air is removed. Then letting engine warm up to 180 F will result i= n 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 t= o only 9 psi. No fluid will leave sys.

 

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 longe= r 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 d= ynamic air bleed, you just make darn sure you purge all air from block sys p= rior to flight. Applying vacuum to rad cap is great way to remove air.

 

One of the ironies about cooling design is tha= t air that resides above engine flow is a safety asset. For example, your ca= p 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.

 

Conversely, air in engine flow has overwhelmin= g negative affect. Temps soar and risks boil over.

 

Clear as mud eh?

 

Fwiw

 

-al wick

 

This message, and the documents attached hereto, is intended only for the ad= dressee and may contain privileged or confidential information. Any unauthor= ized 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 origina= l message. Thank you.
= --Apple-Mail-E406C51C-C65A-4906-9555-1D73BE952E36--