X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ww0-f50.google.com ([74.125.82.50] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTPS id 4961686 for flyrotary@lancaironline.net; Fri, 29 Apr 2011 10:49:43 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.82.50; envelope-from=rwstracy@gmail.com Received: by wwc33 with SMTP id 33so3387151wwc.7 for ; Fri, 29 Apr 2011 07:49:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=kiztDaNacYidM7gtCZ+J5m97WHDpmijKoqns2C1Vmh4=; b=gut46K68NKxFNak13rMR0bQlUIT7TSdpxjCFKjyAQkYxmu7hjcrKqRNZw+Ozk58ts7 Bb0LRCBXZphXDLkl7xhixFYZeAXuPXKfDlNtDXY/5TVqBd1YSvm4GvOgI9IgHw9v5Y7t 8R+/Trdukkd7pVb0jGsfhcpK0e4rkDdcKBfB8= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=sSZbZcquC9p8aBDar5OdEtGPeVA5l2VXODcDrHWkyyBSlqS1AA0YisjOnPz4xZr/TN MZ6qN0Wey38sfuadxLWIJOTd3fr9Ht9Ovxq8KuqyNNGv580p5pCzSnUxKHVWqwHB/itY OAYpa2zpbgYAyxjVRUpxM9ar62fUEGlnKIWYs= MIME-Version: 1.0 Received: by 10.216.79.11 with SMTP id h11mr44341wee.77.1304088540519; Fri, 29 Apr 2011 07:49:00 -0700 (PDT) Received: by 10.216.190.132 with HTTP; Fri, 29 Apr 2011 07:49:00 -0700 (PDT) In-Reply-To: References: Date: Fri, 29 Apr 2011 10:49:00 -0400 Message-ID: Subject: Re: [FlyRotary] Re: Cooling Inlets From: Tracy To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=000e0ce0d120369c4f04a20fc6dc --000e0ce0d120369c4f04a20fc6dc Content-Type: text/plain; charset=ISO-8859-1 Some questions: Prior reading seemed to indicate that the oil cooler did ~1/3 of the cooling, implying a 2/1 ratio on air requirements. This setup seems to have a significantly higher percentage allocated to oil. Is this a byproduct of heat exchanger differences, or the less efficient heat transfer ability of oil, or....? 2nd, assuming similar inlet & diffuser efficiencies, could the inlet areas mentioned be reduced by roughly 1/3 with reasonable expectation of cooling a 2 rotor Renesis? On the subject of exit area: Does either heat exchanger have an exit duct? The RV guys with really fast Lyc powered planes all have some variation of exit ducting to smoothly re-accelerate and redirect exit air parallel to & at or above the slipstream. Even the stock RV-8 has a rounded lip at the bottom of the firewall (which the really fast guys say is much too small a radius...). And there's always the near-mythical P-51 system... Thanks, Charlie The inlets were originally closer to the 2 - 1 area ratio but many experiments (mostly failures) ended up with the current sizes. I just don't have it in me to go back and un-do them all. Also wish I had tried these inlets with my original oil cooler which had about 1/3 more core volume and much thicker. Might have been able to do the oil cooling with less CFM airflow. But, I don't think there is much penalty for having more than enough (but properly faired) inlet area and throttling the airflow with a cowl flap. Yes, I do think both inlets could be scaled down in area for a 2 rotor. Neither of my heat exchangers have exit ducts. Just not enough room to do this in their current locations. Tracy On Thu, Apr 28, 2011 at 4:23 PM, Charlie England wrote: > On 4/28/2011 8:07 AM, Tracy wrote: > > Finally got around to finishing my cooling inlets. (pictures attached) Up > until now they were simply round pipes sticking out of the cowl. The pipes > are still there but they have properly shaped bellmouths on them. The > shape and contours were derived from a NASA contractor report (NASA_CR3485) > that you can find via Google. Lots of math & formulas in it but I just > copied the best performing inlet picture of the contour. Apparently there > is an optimum radius for the inner and outer lip of the inlet. There was > no change to the inlet diameters of 5.25" on water cooler and 4.75" on oil > cooler. > > The simple pipes performed adequately in level flight at moderate cruise > settings even on hot days but oil temps would quickly hit redline at high > power level flight and in climb. > > The significant change with the new inlet shape is that they appear to > capture off-axis air flow (like in climb and swirling flow induced by prop > at high power) MUCH better than the simple pipes. First flight test was > on a 94 deg. F day and I could not get the oil temp above 200 degrees in a > max power climb. They may have gone higher if the air temperature > remained constant but at 3500 fpm the rapidly decreasing OAT kept the temps > well under redline (210 deg F). > > I have an air pressure instrument reading the pressure in front of the oil > cooler and was amazed at the pressure recovered from the prop wash. At 130 > MPH the pressure would almost double when the throttle was advanced to WOT. > That did not happen nearly as much with the simple pipes. > > These inlets ROCK! > > Tracy Crook > > Perfect timing for me; I need to decide whether to take a loss & sell my > (RV-7) James Lyc style cowl & replace it with James' rotary cowl, or just > modify the existing cowl. > > Some questions: > Prior reading seemed to indicate that the oil cooler did ~1/3 of the > cooling, implying a 2/1 ratio on air requirements. This setup seems to have > a significantly higher percentage allocated to oil. Is this a byproduct of > heat exchanger differences, or the less efficient heat transfer ability of > oil, or....? > > 2nd, assuming similar inlet & diffuser efficiencies, could the inlet areas > mentioned be reduced by roughly 1/3 with reasonable expectation of cooling a > 2 rotor Renesis? > > On the subject of exit area: Does either heat exchanger have an exit duct? > The RV guys with really fast Lyc powered planes all have some variation of > exit ducting to smoothly re-accelerate and redirect exit air parallel to & > at or above the slipstream. Even the stock RV-8 has a rounded lip at the > bottom of the firewall (which the really fast guys say is much too small a > radius...). And there's always the near-mythical P-51 system... > > Thanks, > > Charlie > > > --000e0ce0d120369c4f04a20fc6dc Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Some questions:
Prior reading seemed to indicate that the oil cooler did ~1/3 of the cooling, implying a 2/1 ratio on air requirements. This setup seems to have a significantly higher percentage allocated to oil. Is this a byproduct of heat exchanger differences, or the less efficient heat transfer ability of oil, or....?

2nd, assuming similar inlet & diffuser efficiencies, could the inlet areas mentioned be reduced by roughly 1/3 with reasonable expectation of cooling a 2 rotor Renesis?

On the subject of exit area: Does either heat exchanger have an exit duct? The RV guys with really fast Lyc powered planes all have some variation of exit ducting to smoothly re-accelerate and redirect exit air parallel to & at or above the slipstream. Even the stock RV-8 has a rounded lip at the bottom of the firewall (which the really fast guys say is much too small a radius...). And there'= s always the near-mythical P-51 system...

Thanks,
Charlie

The inlets were originally closer to the 2 - 1 area rati= o but many experiments (mostly failures) ended up with the current sizes.= =A0 I just don't have it in me to go back and un-do them all.=A0 Also w= ish I had tried these inlets with my original oil cooler which had about 1/= 3 more core volume and much thicker.=A0=A0 Might have been able to do the o= il cooling with less CFM airflow. =A0 But, I don't think there is much = penalty for having more than enough (but properly faired) inlet area and th= rottling the airflow with a cowl flap.

Yes, I do think both inlets could be scaled down in area for a 2 rotor.=

Neither of my heat exchangers have exit ducts.=A0 Just not enough r= oom to do this in their current locations.

Tracy
=A0


On Thu, Apr 28, 2011 at 4:23 PM, Charlie England= <ceengland= @bellsouth.net> wrote:
=20 =20 =20
On 4/28/2011 8:07 AM, Tracy wrote:
Finally got around to finishing my cooling inlets. (pictures attached)=A0 Up until now they were simply round pipes sticking out of the cowl.=A0=A0 The pipes are still there but they have properl= y shaped bellmouths on them.=A0=A0 The shape and contours were derived from a NASA contractor report (NASA_CR3485) that you can find via Google.=A0 Lots of math & formulas in it but I just copied the best performing inlet picture of the contour.=A0=A0 Apparently there is an optimum radius for the inner and outer lip of the inlet.=A0=A0 There was no change to the inlet diameters of 5.25" on water cooler and 4.75"= ; on oil cooler.

The simple pipes performed adequately in level flight at moderate cruise settings even on hot days but oil temps would quickly hit redline at high power level flight and in climb.=A0

The significant change with the new inlet shape is that they appear to capture off-axis air flow=A0 (like in climb and swirling flow=A0 induced by prop at high power)=A0 MUCH better than the simple pipes. =A0=A0 First flight test was on a 94 deg= . F day and I could not get the oil temp above 200 degrees in a max power climb. =A0=A0 They may have gone higher if the air temperature remained constant but at 3500 fpm the rapidly decreasing OAT kept the temps well under redline (210 deg F).

I have an air pressure instrument reading the pressure in front of the oil cooler and was amazed at the pressure recovered from the prop wash.=A0 At 130 MPH the pressure would almost double when the throttle was advanced to WOT. =A0 That did not happen nearly as much with the simple pipes.=A0=A0

These inlets ROCK!

Tracy Crook

Perfe= ct timing for me; I need to decide whether to take a loss & sell my (RV-7)=A0 James Lyc style cowl & replace it with James' rotary cowl, or just modify the existing cowl.

Some questions:
Prior reading seemed to indicate that the oil cooler did ~1/3 of the cooling, implying a 2/1 ratio on air requirements. This setup seems to have a significantly higher percentage allocated to oil. Is this a byproduct of heat exchanger differences, or the less efficient heat transfer ability of oil, or....?

2nd, assuming similar inlet & diffuser efficiencies, could the inlet areas mentioned be reduced by roughly 1/3 with reasonable expectation of cooling a 2 rotor Renesis?

On the subject of exit area: Does either heat exchanger have an exit duct? The RV guys with really fast Lyc powered planes all have some variation of exit ducting to smoothly re-accelerate and redirect exit air parallel to & at or above the slipstream. Even the stock RV-8 has a rounded lip at the bottom of the firewall (which the really fast guys say is much too small a radius...). And there'= s always the near-mythical P-51 system...

Thanks,

Charlie



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