X-Virus-Scanned: clean according to Sophos on Logan.com From: "David Leonard" Received: from mail-qg0-f44.google.com ([209.85.192.44] verified) by logan.com (CommuniGate Pro SMTP 6.1.2) with ESMTPS id 7693830 for flyrotary@lancaironline.net; Fri, 15 May 2015 12:49:12 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.192.44; envelope-from=wdleonard@gmail.com Received: by qgfh8 with SMTP id h8so3817768qgf.3 for ; Fri, 15 May 2015 09:48:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=0R67TQR5RzNv04R3twwgr+z6gCeDYoHXm6UpUbPj2+0=; b=DlGDadeasUDTDdhzvQazPflcI1UoNvDNEM4KzTyY8fGp+amyDlZ6/GZZcxi2ow+js8 UFkPDoRV6NaEacT6TscKZCZQLpE/ULPeKvKrF4OBz0Dvus3FGohlnVw03yTcNDdLuTnN XFU9ZtykYSU3ifANwbkKXAyfORVV7SI7oeE5hyajnfIRNqf1Y0JNEHOkPY24hmUBQRrI zc67dpIK4KY6p6aXUwR6iRfvfQT09SK5kp8winFawTCts/3NhCHd+pm+V5odVd6o3Hj0 MgXUEWBOotVBaPGH8zUAoNOfCocsOTZ1ruFZFP1GFOu9wgUIvmFcQiJKUIpCDjB2dTbn TB5g== MIME-Version: 1.0 X-Received: by 10.55.22.65 with SMTP id g62mr22625852qkh.72.1431708518126; Fri, 15 May 2015 09:48:38 -0700 (PDT) Received: by 10.140.29.198 with HTTP; Fri, 15 May 2015 09:48:38 -0700 (PDT) In-Reply-To: References: Date: Fri, 15 May 2015 09:48:38 -0700 Message-ID: Subject: Re: [FlyRotary] Return to Flight - 2 To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=001a1147740ca51a0c0516219dd5 --001a1147740ca51a0c0516219dd5 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sorry to hear that Jeff. My apologies if you have already posted pictures of the your installation and the diffuser, but could you post some now? Dave Leonard On Fri, May 15, 2015 at 8:19 AM, Jeff Whaley wrote: > Well, the second flight occurred last night with same results as before; > one short low-level circuit due to insufficient cooling =E2=80=A6 looks l= ike Al > Wick made the correct prediction. > > 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 t= he > pinched diffuser. I will do all 3 and see what happens. > > If all of the above show remarkable improvement then repositioning the > radiator is the only alternative. > > Jeff > > > > *From:* Bobby J. Hughes [mailto:flyrotary@lancaironline.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 has no significant effect on = cooling > efficiency (heat transfer). The next time you fly, since you=E2=80=99ve r= emoved > 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 exchanger I would expect > 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 aircraft > *Subject:* [FlyRotary] Re: Return to Flight > > > > Hi Jeff. I=E2=80=99ve done lot=E2=80=99s of experimenting with cooling sy= s. 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 pressu= re would > have been 9 psi. 1 cup, 14 psi. No air in system, then you would have see= n > rated cap pressure (16 psi in your case). > > > > 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 r= emoved > 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 t= hat 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 inflat= es > cooling temp. > > > > 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. > > > > 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. Sup= er > 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. > > > > 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 vacu= um > to rad cap is great way to remove air. > > > > 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 oth= er > assets to this design. > > > > Conversely, air in engine flow has overwhelming 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 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. > --001a1147740ca51a0c0516219dd5 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Sorry to hear that Jeff.=C2=A0 My apologies if you have al= ready posted pictures of the your installation and the diffuser, but could = you post some now?

Dave Leonard

On Fri, May 15, 2015 at 8:19 A= M, Jeff Whaley <flyrotary@lancaironline.net> wrote= :

Well, the second flight o= ccurred last night with same results as before; one short low-level circuit= due to insufficient cooling =E2=80=A6 looks like Al Wick made the correct prediction.

There are 3 things I can = try with the current configuration: 1) Increase inlet area 2) Increase outl= et area (adjustable cowl flap) 3) Re-profile the pinched diffuser.=C2=A0 I will do all 3 and see what happens.=

If all of the above show = remarkable improvement then repositioning the radiator is the only alternat= ive.

Jeff=

=C2=A0

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

=C2=A0

Al,<= /p>

=C2=A0

=E2=80=9CSorry to say, the pressure you see = has no significant effect on cooling efficiency (heat transfer). The next t= ime you fly, since you=E2=80=99ve removed most of that air, you will still see 210F. Just like before=E2=80=9D.

=C2=A0

If the air was trapped at the top of the hea= t exchanger I would expect improved temperatures. Could be wrong.

=C2=A0

Bobby Hughes

=C2=A0

=C2=A0

=C2=A0

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

=C2=A0

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 y= our case).

=C2=A0

Sorry to say, the pressure you see has no si= gnificant effect on cooling efficiency (heat transfer). The next time you f= ly, 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 sta= tement, 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 effec= t. Causes local boiling when it passes hot areas and inflates cooling temp.

=C2=A0

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 r= esult 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 pressur= e to only 9 psi. No fluid will leave sys.

=C2=A0

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 f= low. This is called a dynamic bleed. Air is automatically removed from engine coolant flow. Super low risk way to fly as you no long= er care if air is in system. It=E2=80=99s can=E2=80=99t affect cooling.

=C2=A0

It=E2=80=99s a bit higher risk to fly withou= t dynamic air bleed, you just make darn sure you purge all air from block s= ys prior to flight. Applying vacuum to rad cap is great way to remove air.

=C2=A0

One of the ironies about cooling design is t= hat 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 lo= ng before overheating. A bunch of other assets to this design.

=C2=A0

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

=C2=A0

Clear as mud eh?

=C2=A0

Fwiw

=C2=A0

-al wick

=C2=A0

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 origin= al message. Thank you.

--001a1147740ca51a0c0516219dd5--