X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [64.129.170.194] (HELO VIRCOM1.fcdata.private) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4962136 for flyrotary@lancaironline.net; Fri, 29 Apr 2011 18:14:03 -0400 Received-SPF: none receiver=logan.com; client-ip=64.129.170.194; envelope-from=cbarber@texasattorney.net Received: from FCD-MAIL06.FCDATA.PRIVATE ([fe80::697f:d6aa:b87:78d8]) by FCD-MAIL05.FCDATA.PRIVATE ([fe80::809d:a06e:5913:452e%15]) with mapi id 14.01.0270.001; Fri, 29 Apr 2011 17:08:38 -0500 From: Chris Barber To: Rotary motors in aircraft Subject: RE: [FlyRotary] Re: Cooling Inlets Thread-Topic: [FlyRotary] Re: Cooling Inlets Thread-Index: AQHMBrFCxR+Ra2PEPEeLQTBOQV4l0pR1Ygwo Date: Fri, 29 Apr 2011 22:12:51 +0000 Message-ID: <2D41F9BF3B5F9842B164AF93214F3D3065A69537@FCD-MAIL06.FCDATA.PRIVATE> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [166.139.76.11] Content-Type: multipart/alternative; boundary="_000_2D41F9BF3B5F9842B164AF93214F3D3065A69537FCDMAIL06FCDATA_" MIME-Version: 1.0 --_000_2D41F9BF3B5F9842B164AF93214F3D3065A69537FCDMAIL06FCDATA_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Oh oh oh....Mr. Kotter, Mr. Kotter...oh oh oh. Yes, I am using NACA (don't let Paul L know...he may hunt me down) scoops o= n top of my Velocity SE per plans. IIRC, Velocity had cooling issues with = the original arm pit scoops. They apparently solved the problems with the = top mounted NACA's. It is my understanding that the boundary layer stays a= ttached as it comes over the top of the fuselage and enters the NACA's. Th= ey then have ducting that directs the air to the Lyc jugs. Some enhance th= is further with VG's. The relatively large NACA's dump directly into a chamber that consists of t= he radiator as the chambers back wall (mounted directly in front of the eng= ine pretty much like in a car) and the oil cooler as the chambers floor wit= h a couple of steering tubes to better force some air to the floor through = the chamber). I also have a front mounted oil cooler in parallel (a series= mount had me leaking oil out of the remotely mounted filter...seems the fr= ont aviation oil cooler was backing up the system....no issue now that it i= s mounted in parallel. No, I have not flown, however, I can cool all day on the ground at idle. I= do have a pretty large radiator (smack dab in between size of John Slades = and Dave Leonards at 22X19x3=3D1254.) It is a stock second gen oil cooler = with a Velocity provided front oil cooler that also provides some cabin hea= t (in addition to the Seamech/KPAC A/C I am currently installing for cabin = comfort...the condenser is installed on the bottom of the cowling and stand= ard scoop will feed the A/C condenser and turbo intercooler. This condense= r set up is copied from the Velocity twin turbo which uses the same A/C sys= tem. Chris Barber Houston. Velocity N17010 ________________________________ From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of = Dwayne Parkinson [dwayneparkinson@yahoo.com] Sent: Friday, April 29, 2011 4:05 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Cooling Inlets OK, I gotta ask. Does anyone use NACA ducts for cooling inlets? Why or wh= y not? ________________________________ 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 coolin= g, implying a 2/1 ratio on air requirements. This setup seems to have a sig= nificantly 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 bo= ttom of the firewall (which the really fast guys say is much too small a ra= dius...). 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 experime= nts (mostly failures) ended up with the current sizes. I just don't have i= t 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 t= hicker. 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 (bu= t 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 pipe= s are still there but they have properly shaped bellmouths on them. The s= hape 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 cop= ied 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 co= oler. The simple pipes performed adequately in level flight at moderate cruise se= ttings even on hot days but oil temps would quickly hit redline at high pow= er level flight and in climb. The significant change with the new inlet shape is that they appear to capt= ure 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 o= n a 94 deg. F day and I could not get the oil temp above 200 degrees in a m= ax power climb. They may have gone higher if the air temperature remaine= d constant but at 3500 fpm the rapidly decreasing OAT kept the temps well u= nder 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 (R= V-7) James Lyc style cowl & replace it with James' rotary cowl, or just mo= dify the existing cowl. Some questions: Prior reading seemed to indicate that the oil cooler did ~1/3 of the coolin= g, implying a 2/1 ratio on air requirements. This setup seems to have a sig= nificantly 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 bo= ttom of the firewall (which the really fast guys say is much too small a ra= dius...). And there's always the near-mythical P-51 system... Thanks, Charlie --_000_2D41F9BF3B5F9842B164AF93214F3D3065A69537FCDMAIL06FCDATA_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Oh oh oh...= .Mr. Kotter, Mr. Kotter= ...oh oh oh.

 

Yes, I am using NACA (don't let Paul L = know...he may hunt me down) scoops on top of my Velocity SE per plans. = ; IIRC, Velocity had cooling issues with the original = arm pit scoops.  They apparently solved the problems with the top mounted NACA's.  It is= my understanding that the boundary layer stays attached as it comes over the top of the fuselage and enters the N= ACA's.  They then have ducting that directs the air to the Lyc jugs.  Some= enhance this further with VG's.

 

The relatively large NACA's=  dump directly into a chamber that consists of the radiator as the cha= mbers back wall (mounted directly in front of the engine pretty much like i= n a car) and the oil cooler as the chambers floor with a couple of steering tubes to better force some air to th= e floor through the chamber).  I also have a front mounted oil cooler = in parallel (a series mount had me leaking oil out of the = remotely mounted filter...seems the front aviation oil cooler was backing up the system....no issue now that it is mounted in= parallel.

 

No, I have not flown, however, I can cool all day on the ground at idle.=   I do have a pretty large radiator (smack dab in between size of John=  Slades and Dave Leonards at 22X19x3=3D1254.)  It is a stock second gen oil cooler with a Velocity provided front oil coo= ler that also provides some cabin heat (in addition to the Seamech/KPAC A/C I am currently ins= talling for cabin comfort...the condenser is installed on the bottom of the cowling and standard scoop will feed the= A/C condenser and turbo intercooler.  This condenser= set up is copied from the Velocity twin turbo which uses the same A= /C system.

 

Chris Barber

Houston.

Velocity N17010

From: Rotary motors in aircraft [flyrotary= @lancaironline.net] on behalf of Dwayne Parkinson [dwayneparkinson@yahoo.co= m]
Sent: Friday, April 29, 2011 4:05 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Cooling Inlets

OK, I gotta ask.  Does anyone use NACA ducts for cooling inlets? =  Why or why not?  
From: Tracy <rwstracy@gm= ail.com>
To: Rotary motors in aircra= ft <flyrotary@lancaironline.net>
Sent: Fri, April 29, 2011 9= :49:00 AM
Subject: [FlyRotary] Re: Co= oling Inlets

Some questions:
Prior reading seemed to indicate that the oil cooler did ~1/3 of the coolin= g, implying a 2/1 ratio on air requirements. This setup seems to have a sig= nificantly 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 ar= eas mentioned be reduced by roughly 1/3 with reasonable expectation of cool= ing 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 &a= mp; 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 experime= nts (mostly failures) ended up with the current sizes.  I just don't h= ave it in me to go back and un-do them all.  Also wish I had tried the= se inlets with my original oil cooler which had about 1/3 more core volume and much thicker.   Might have be= en able to do the oil cooling with less CFM airflow.   But, I don't th= ink 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 t= o do this in their current locations.

Tracy
 


On Thu, Apr 28, 2011 at 4:23 PM, Charlie England= <ceengland@bellsouth.net> wrote:
On 4/28/2011 8:07 AM, Tracy wrote:
Finally got around to finishing my cooling inlets. (pictures att= ached)  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 wer= e 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 co= oler and 4.75" on oil cooler.

The simple pipes performed adequately in level flight at moderate cruise se= ttings even on hot days but oil temps would quickly hit redline at high pow= er level flight and in climb. 

The significant change with the new inlet shape is that they appear to capt= ure 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.  A= t 130 MPH the pressure would almost double when the throttle was advanced t= o 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 modi= fy the existing cowl.

Some questions:
Prior reading seemed to indicate that the oil cooler did ~1/3 of the coolin= g, implying a 2/1 ratio on air requirements. This setup seems to have a sig= nificantly 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 ar= eas mentioned be reduced by roughly 1/3 with reasonable expectation of cool= ing 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 &a= mp; 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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