X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 01 Jun 2010 11:33:46 -0400 Message-ID: X-Original-Return-Path: Received: from mail.centurybankonline.com ([151.213.202.2] verified) by logan.com (CommuniGate Pro SMTP 5.3.7) with ESMTP id 4332450 for lml@lancaironline.net; Tue, 01 Jun 2010 09:42:32 -0400 Received-SPF: pass receiver=logan.com; client-ip=151.213.202.2; envelope-from=prvs=1768a7fe19=ChatDaniel@CenturyBankOnline.com Received: from mail.centurybankonline.com (127.0.0.1) by mail.centurybankonline.com (MlfMTA v3.2r9) id h0kcg40171s6 for ; Tue, 1 Jun 2010 10:27:43 -0400 (envelope-from ) Received: from Exchange.Century.local ([10.225.40.32]) by mail.centurybankonline.com (SonicWALL 7.2.1.2841) with ESMTP; Tue, 01 Jun 2010 10:27:43 -0400 Received: from Exchange.Century.local ([::1]) by Exchange.Century.local ([::1]) with mapi; Tue, 1 Jun 2010 09:42:29 -0400 From: Chat Daniel X-Original-To: Lancair Mailing List X-Original-Date: Tue, 1 Jun 2010 09:42:27 -0400 Subject: RE: [LML] Re: FW: [LML] Re: cowl flap cooling drag reduction Thread-Topic: [LML] Re: FW: [LML] Re: cowl flap cooling drag reduction Thread-Index: AcsA0MNLXQwbCzVWSCeQetwL6iWCzAAvr+mA X-Original-Message-ID: <224AEB147425D947B9FE2AE2B54E8B2C328D4D3F@Exchange.Century.local> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_224AEB147425D947B9FE2AE2B54E8B2C328D4D3FExchangeCentury_" MIME-Version: 1.0 X-Mlf-Version: 7.2.1.2841 X-Mlf-UniqueId: o201006011427430083927 --_000_224AEB147425D947B9FE2AE2B54E8B2C328D4D3FExchangeCentury_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I have an RV and an ES. When RV8 guys put the 200hp Lycoming in their plan= es, they had cooling problems. One interesting way they dealt with it was = to install a louver vent on the bottom of the cowl similar to your heating = vent at home. This vent had a sliding plate on the inside to open and clos= e it. It produced a nice low pressure pull when open and very little drag.= It was also easy to install. Just a thought. Chat Daniel Super ES N891AC RV8 891AC From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Terr= ence O'Neill Sent: Monday, May 31, 2010 10:51 AM To: lml@lancaironline.net Subject: [LML] Re: FW: [LML] Re: cowl flap cooling drag reduction Many thanks for the info. Another vote for retaining the inlet area, and m= odifying the cowl to closeable cowl flaps. Again reminds me of watching the cowl flaps close down to not more than a c= rack around the P2V's big CW 3350s when going to cruise... and marvelling a= t how such a small amount of exit air could cool those big engines... Als= o intend to try to radius the bottom of the firewall in the cowl exit area.= .. trickey geometry at the nosewheel strut... and maybe make a sealing fair= ing around the two exhaust stacks on the left side of the cowl. Terrence L235/320 N211AL On May 30, 2010, at 8:54 AM, Frederick Moreno wrote: I put cowl flaps on my Lancair IV along with a top cooling air plenum and = I also went to fairly extreme measures to eliminate cooling leakage around = the engine. Inlet area remained unchanged (6 inch diameter) although the i= nlets were raised 1.5 inches for a straight shot in and moved outboard 1.0 = inch so that I could insert a boundary layer dam between spinner and inlets= . This removes the boundary layer coming off the spinner as well as the sl= ower-moving separated wake flow at the shank of the propeller where it ente= rs the spinner. I drastically cut the exit area with cowl flaps closed com= pared to the stock Lancair outlets which are meant for turbo engines at 25,= 000 feet. (I believe turbo engines would gain no benefit from closable cow= l flaps - they need all that air flow at altitude.) Net result was that overall flat plate drag area went down (compared to st= ock) perhaps 7-10% with the cowl flaps closed, and it runs cold at 65% lean= of peak, CHTs below 300F, lower than 250F at low altitudes. With cowl fla= ps open (and lots of exit area) I can climb unrestricted at Vy (135 knots, = best power) starting at near sea level on a 90F day. Difference between co= wl flaps closed and faired and wide open and deflected outward about three = inches is about ten knots. That does NOT mean a ten knot speed improvement= over stock. It means that when the cowl flaps are open, they are draggy. I have measured pressure drop across the engine and even with cowl flaps cl= osed, it is too high (too much cooling air, confirming temperature data). = So last week I made modifications to reduce the closed cowl flap exit area = another 25%. No testing yet. Would I do it again? Maybe. It was a lot of work. Estimate of the overal= l speed benefit: perhaps 3.0-3.5%. It sure is nice to climb unrestricted o= n a hot day. Fred Thanks, Gary. Okay, so I think I would keep the L235 cowl inlet area as-is, and be genero= us with the flappable outlet area. Actual experience is very reassuring. Terrence L235/320 N2111AL I also reduced the inlet area about 20%, adding a diffuser section. The o= utlet area was reduced to about half of the original, depending on what kin= d of bulges on the bottom are assumed to be "standard." The cooling is mar= ginal, but adequate - on hot days climb speeds have to be increased and cru= ise is done with the flaps open. This is to keep the CHT's below 400 and o= il below 220. Closing the relatively small cowl flaps increases the speed = by 2 to 4 knots. ES #157, Lycoming engine ________________________________ CONFIDENTIALITY NOTICE: This email transmission may contain information tha= t is proprietary, privileged, and/or confidential and is intended exclusive= ly for the person(s) to whom it is addressed. This communication represents= the originator's personal views and opinions, which do not necessarily ref= lect those of Century Bank & Trust. This email and its attachments are beli= eved to be free of any virus or defect, but it is the responsibility of the= recipient to ensure that this is true. Century Bank does not accept respon= sibility or liability for any loss or damage arising in any way from the re= ceipt or use of this email or for any errors or omissions in its contents w= hich may arise as a result of its transmission. Any use, copying, retention= or disclosure by any person other than the intended recipient or the inten= ded recipient's designees is strictly prohibited. If you are the intended r= ecipient, you must treat the information in confidence and in accordance wi= th all laws related to the privacy and confidentiality of such information.= If you are not the intended recipient or their designee, please notify the= sender immediately by return email and delete all copies of this email, in= cluding all attachments. Thank You. --_000_224AEB147425D947B9FE2AE2B54E8B2C328D4D3FExchangeCentury_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

I have an RV and an ES.  When RV8 guys put the 200hp Ly= coming in their planes, they had cooling problems.  One interesting wa= y they dealt with it was to install a louver vent on the bottom of the cowl similar to your heating vent at ho= me.  This vent had a sliding plate on the inside to open and close it.=   It produced a nice low pressure pull when open and very little drag.=   It was also easy to install.  Just a thought.=

Chat Daniel

Super ES N891AC

RV8 891AC

 

From: Lancair = Mailing List [mailto:lml@lancaironline.net] On Behalf Of Terrence O'Neill
Sent: Monday, May 31, 2010 10:51 AM
To: lml@lancaironline.net
Subject: [LML] Re: FW: [LML] Re: cowl flap cooling drag reduction

 

Many thanks for the info.  Another vote for ret= aining the inlet area, and modifying the cowl to closeable cowl flaps.=

Again reminds me of watching the cowl flaps close do= wn to not more than a crack around the P2V's big CW 3350s when going to cru= ise... and marvelling at how such a small amount of exit air could cool tho= se big engines...   Also intend to try to radius the bottom of the firewall in the cowl exit area... trickey = geometry at the nosewheel strut... and maybe make a sealing fairing around = the two exhaust stacks on the left side of the cowl.

 

Terrence 

L235/320  N211AL

 

 

On May 30, 2010, at 8:54 AM, Frederick Moreno wrote:=



I put cowl flaps on my Lancair  IV along with a top cooling = air plenum and I also went to fairly extreme measures to eliminate cooling = leakage around the engine.  Inlet area remained unchanged (6 inch diameter) although the inlets were raised 1.5 inches for= a straight shot in and moved outboard 1.0 inch so that I could insert a bo= undary layer dam between spinner and inlets.  This removes the boundar= y layer coming off the spinner as well as the slower-moving separated wake flow at the shank of the propeller whe= re it enters the spinner.  I drastically cut the exit area with cowl f= laps closed compared to the stock Lancair outlets which are meant for turbo= engines at 25,000 feet.  (I believe turbo engines would gain no benefit from closable cowl flaps – they = need all that air flow at altitude.)=

 

Net result was that overall flat plate drag area  went down = (compared to stock) perhaps 7-10% with the cowl flaps closed, and it runs c= old at 65% lean of peak, CHTs below 300F, lower than 250F at low altitudes.  With cowl flaps open (and lots of exit a= rea) I can climb unrestricted at Vy (135 knots, best power) starting at nea= r sea level on a 90F day.  Difference between cowl flaps closed and fa= ired and wide open and deflected outward about three inches is about ten knots.  That does NOT mean a ten knot speed= improvement over stock.  It means that when the cowl flaps are open, = they are draggy. 

 

I have measured pressure drop across the engine and even with cow= l flaps closed, it is too high (too much cooling air, confirming temperatur= e data).  So last week I made modifications to reduce the closed cowl flap exit area another 25%.  No testing yet= .

 

Would I do it again?  Maybe.  It was a lot of work.&nbs= p; Estimate of the overall speed benefit: perhaps 3.0-3.5%.  It sure i= s nice to climb unrestricted on a hot day. 

 

Fred

 

 

Thanks, Gary.  =

Okay, so I think I would keep t= he L235 cowl inlet area as-is, and be generous with the flappable outlet ar= ea.

Actual experience is very reass= uring.

Terrence

L235/320 N2111AL

 

 


 I also reduced the inlet area about 20%, adding a diffuser section.&n= bsp; The outlet area was reduced to about half of the original, depending o= n what kind of bulges on the bottom are assumed to be "standard."=   The cooling is marginal, but adequate - on hot days climb speeds have to be increased and cruise is done with the flaps open.&= nbsp; This is to keep the CHT's below 400 and oil below 220.  Closing = the relatively small cowl flaps increases the speed by 2 to 4 knots. <= o:p>

ES #157, Lycoming engine

 

 

 


CONFIDENTIALITY NOTICE: This= email transmission may contain information that is proprietary, privileged= , and/or confidential and is intended exclusively for the person(s) to whom= it is addressed. This communication represents the originator’s personal views and opinions, which do not necessari= ly reflect those of Century Bank & Trust. This email and its attachment= s are believed to be free of any virus or defect, but it is the responsibil= ity of the recipient to ensure that this is true. Century Bank does not accept responsibility or liability for any los= s or damage arising in any way from the receipt or use of this email or for= any errors or omissions in its contents which may arise as a result of its= transmission. Any use, copying, retention or disclosure by any person other than the intended recipient or= the intended recipient’s designees is strictly prohibited. If you ar= e the intended recipient, you must treat the information in confidence and = in accordance with all laws related to the privacy and confidentiality of such information. If you are not the in= tended recipient or their designee, please notify the sender immediately by= return email and delete all copies of this email, including all attachment= s. Thank You.
 --_000_224AEB147425D947B9FE2AE2B54E8B2C328D4D3FExchangeCentury_--