X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.122] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4962188 for flyrotary@lancaironline.net; Fri, 29 Apr 2011 19:27:58 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.122; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=2pE2Kh9Ye2ywHyyFZnC5ZQ1FvuPrdOtuPO5uN4ysVDU= c=1 sm=0 a=RKxS59jiEN8A:10 a=rPkcCx1H5rrOSfN0dPC7kw==:17 a=arxwEM4EAAAA:8 a=r1ClD_H3AAAA:8 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=pedpZTtsAAAA:8 a=L1aB_4vkADVbsOcMM20A:9 a=y80kStc7zVOcrpSxLEwA:7 a=wPNLvfGTeEIA:10 a=MSl-tDqOz04A:10 a=EzXvWhQp4_cA:10 a=eJojReuL3h0A:10 a=CjxXgO3LAAAA:8 a=vpvNTXneG4DuHjxPSMYA:9 a=dbgAAhAKpqjjgzR5gPYA:7 a=rC2wZJ5BpNYA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.167.5 Received: from [174.110.167.5] ([174.110.167.5:62840] helo=EdPC) by cdptpa-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id E6/2D-05159-A594BBD4; Fri, 29 Apr 2011 23:27:23 +0000 Message-ID: From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Cooling Inlets Date: Fri, 29 Apr 2011 19:26:51 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0048_01CC06A3.63CD3310" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 This is a multi-part message in MIME format. ------=_NextPart_000_0048_01CC06A3.63CD3310 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dwayne There is a NACA study on NACA ducts which in essence found that while = they were excellent for feeding an intake (an duct with no internal = resistance such as a heat exchanger core) such as an engine intake, that = their performance suffered relative to other duct configurations - where = you had a radiator core installed. The reason appeared to be that the = pressure build up before the core hindered the airflow into the duct and = caused a lot of the air to flow around the opening. On the good side, = they were relatively low drag ducts. =20 Now that being said, several approaches have been found that seems to = offset the problems. One that comes to mind is the placement of vortex = generators which guide more airflow into the ducts and the other one is = the placement of the inlet in a high pressure area. Folks have used = them successfully for cooling - so long as sufficient airflow can be = achieved through the duct the core doesn't care what kind of opening is = used. Ed Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 http://www.andersonee.com http://www.eicommander.com From: Dwayne Parkinson=20 Sent: Friday, April 29, 2011 5:05 PM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Cooling Inlets OK, I gotta ask. Does anyone use NACA ducts for cooling inlets? Why or = why not? =20 -------------------------------------------------------------------------= ------- From: Tracy To: Rotary motors in aircraft Sent: Fri, April 29, 2011 9:49:00 AM Subject: [FlyRotary] Re: Cooling Inlets 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 =20 On Thu, Apr 28, 2011 at 4:23 PM, Charlie England = wrote: On 4/28/2011 8:07 AM, Tracy wrote:=20 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. =20 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. =20 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 ------=_NextPart_000_0048_01CC06A3.63CD3310 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dwayne
 
There is a NACA study on NACA ducts which in = essence found=20 that while they were excellent for feeding an intake (an duct with no = internal=20 resistance such as a heat exchanger core) such as an engine intake, that = their=20 performance suffered relative to other duct configurations - where = you had=20 a radiator core installed.  The reason appeared to be that the = pressure=20 build up before the core hindered the airflow into the duct and caused a = lot of=20 the air to flow around the opening. On the good side, they were = relatively low=20 drag ducts. 
 
Now that being said, several approaches have = been found=20 that seems to offset the problems.  One that comes to mind is the = placement=20 of vortex generators which guide more airflow into the ducts and the = other one=20 is the placement of the inlet in a high pressure area.  Folks have = used=20 them successfully for cooling - so long as sufficient airflow can be = achieved=20 through the duct the core doesn't care what kind of opening is=20 used.
 
Ed
 
Edward L. Anderson
Anderson Electronic = Enterprises=20 LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com

Sent: Friday, April 29, 2011 5:05 PM
Subject: [FlyRotary] Re: Cooling Inlets

OK, I gotta ask.  Does anyone use NACA ducts for cooling = inlets?=20  Why or why not?  

From: Tracy <rwstracy@gmail.com>
To: Rotary motors in aircraft = <flyrotary@lancaironline.net>
Sent: Fri, April 29, 2011 9:49:00 = AM
Subject: = [FlyRotary] Re:=20 Cooling Inlets

Some questions:
Prior reading seemed to = indicate=20 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=20 efficient heat transfer ability of oil, or....?

2nd, assuming = similar=20 inlet & diffuser efficiencies, could the inlet areas mentioned be = reduced by=20 roughly 1/3 with reasonable expectation of cooling a 2 rotor = Renesis?

On=20 the subject of exit area: Does either heat exchanger have an exit duct? = The RV=20 guys with really fast Lyc powered planes all have some variation of exit = ducting=20 to smoothly re-accelerate and redirect exit air parallel to & at or = above=20 the slipstream. Even the stock RV-8 has a rounded lip at the bottom of = the=20 firewall (which the really fast guys say is much too small a radius...). = And=20 there's always the near-mythical P-51=20 system...

Thanks,
Charlie

The inlets were originally = closer to=20 the 2 - 1 area ratio but many experiments (mostly failures) ended up = with the=20 current sizes.  I just don't have it in me to go back and un-do = them=20 all.  Also wish I had tried these inlets with my original oil = cooler which=20 had about 1/3 more core volume and much thicker.   Might have = been=20 able to do the oil cooling with less CFM airflow.   But, I don't = think=20 there is much penalty for having more than enough (but properly faired) = inlet=20 area and throttling the airflow with a cowl flap.

Yes, I do think = both=20 inlets could be scaled down in area for a 2 rotor.

Neither of my = heat=20 exchangers have exit ducts.  Just not enough room to do this in = their=20 current locations.

Tracy
 


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

The simple pipes performed adequately in level = flight at=20 moderate cruise settings even on hot days but oil temps would = quickly hit=20 redline at high power level flight and in climb. 

The=20 significant change with the new inlet shape is that they appear to = capture=20 off-axis air flow  (like in climb and swirling flow  = induced by=20 prop at high power)  MUCH better than the simple pipes. =   =20 First flight test was on a 94 deg. F day and I could not get the oil = temp=20 above 200 degrees in a max power climb.    They may have = gone=20 higher if the air temperature remained constant but at 3500 fpm the = rapidly=20 decreasing OAT kept the temps well under redline (210 deg = F).

I have=20 an air pressure instrument reading the pressure in front of the oil = cooler=20 and was amazed at the pressure recovered from the prop wash.  = At 130=20 MPH the pressure would almost double when the throttle was advanced = to WOT.=20   That did not happen nearly as much with the simple = pipes.  =20

These inlets ROCK!

Tracy=20 Crook

Perfect timing for me; I need to decide = whether to=20 take a loss & sell my (RV-7)  James Lyc style cowl=20 & replace it with James' rotary cowl, or just = modify=20 the existing cowl.

Some questions:
Prior reading seemed to = indicate=20 that the oil cooler did ~1/3 of the cooling, implying a 2/1 ratio on = air=20 requirements. This setup seems to have a significantly higher = percentage=20 allocated to oil. Is this a byproduct of heat exchanger differences, = or the=20 less efficient heat transfer ability of oil, or....?

2nd, = assuming=20 similar inlet & diffuser efficiencies, could the inlet areas = mentioned be=20 reduced by roughly 1/3 with reasonable expectation of cooling a 2 = rotor=20 Renesis?

On the subject of exit area: Does either heat = exchanger have=20 an exit duct? The RV guys with really fast Lyc powered planes all have = some=20 variation of exit ducting to smoothly re-accelerate and redirect exit = air=20 parallel to & at or above the slipstream. Even the stock RV-8 has = a=20 rounded lip at the bottom of the firewall (which the really fast guys = say is=20 much too small a radius...). And there's always the near-mythical P-51 = = system...

Thanks,

Charlie



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