Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP id 742338 for flyrotary@lancaironline.net; Wed, 16 Feb 2005 23:01:57 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.rr.com [24.74.185.127]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j1H41Abp004185 for ; Wed, 16 Feb 2005 23:01:11 -0500 (EST) Message-ID: <002601c514a5$52aac5d0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: 3" Duct Was: [FlyRotary] Re: I found the power Date: Wed, 16 Feb 2005 23:01:09 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0023_01C5147B.673DE650" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0023_01C5147B.673DE650 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Paul, I use a 3" dia SCAT tube which undoubtedly causes some loss of = pressure, but much better than sucking in hot air from under the = cowling. I used to know a rule of thumb formula that told you how much = power you lost for each 10F temp rise, I think it was 1% power loss for = each 10F. If correct then with an OAT of say 60F , your under-the-cowl = air temp could easily be 120F. A 60 deg rise of temp =3D 6% loss in = power. So say you are making 162HP at 5600 on a 60F day. You put the = cowl on and the temps go to 120F, 6% of 162 =3D 9.72 HP loss or down to = 150.28HP. . =20 My spreadsheet shows that a 9.72 HP drop to 150.28HP would give you an = rpm of around 5150 - 5200. This sounds fairly consistent with what you = are seeing, I believe. With my cowl off my static might be 5300 rpm - with my cowling on with = SCAT attached to the throttle body I get at least 5600 rpm and perhaps = 5800 on a cooler day. So I think say 7-9 HP is too much to give up to = hot air. Duct that sucker. Ed A ----- Original Message -----=20 From: Paul=20 To: Rotary motors in aircraft=20 Sent: Wednesday, February 16, 2005 8:54 PM Subject: [FlyRotary] Re: I found the power Thanks, Ed....I think the results of my on-again-off-again cowl = experiments pretty well proved this. Do you think that SCAT or SCEET = tubing (the one with the wire reinforcement, whichever that one is) = would create too much drag on the incoming air? Paul Conner ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Wednesday, February 16, 2005 6:07 PM Subject: [FlyRotary] Re: I found the power Paul, If you are not routing outside air to your engine intake, you are = giving up power. The less dense, hot air underneath the cowling will = take 200-400 rpm away from your rotary. The NACA ducts should work well = for this application. Ed A ----- Original Message -----=20 From: Paul=20 To: Rotary motors in aircraft=20 Sent: Wednesday, February 16, 2005 6:26 PM Subject: [FlyRotary] I found the power Today I finished installing the firesleeve on the remaing fuel = lines, made some stand-offs so that the fuel lines would not be right up = against the engine, and finished hooking up and securing a few other = items. With the top cowling off, I ran the pumps for a minute, then = checked for leaks...none found. Then I started the engine and ran it = for 20 or so seconds and shut it down and reinspected for fuel leaks. = None found. I restarted and taxiied away from the hangar a bit so as to = not be as loud for others in and near the hangar and did a full power = runup. I hit 5600 static rpm's. In the past, the best I could hope for = was 5200, most of the time settling for 5100 rpm's. I taxiied back in = and installed the top cowling....max rpm's 5100. Took the top cowling = back off....max rpm's 5600. One more try....5100 with the cowling back = on. It is beginning to become more clear to me, that one of two things = are affecting rpm's. Option one is that with the top cowling on the = engine is ingesting heated air and just cannot develop the same power as = when it ingests outside unheated air. Option two is the muffler bearing = may be worn. I'm kinda leaning toward option one. I was thinking of installing two small NACA ducts on the = bottom of my cowling with two hoses coming up to feed air to my TWM = throttlebody. The NACA ducts I purchased from Van's RV (made for = cowling ventilation) already have a male outlet already molded in the = assembly, so you just slide a hose over it and secure with a clamp. Very = simple installation.(Works well for my cabin ventillation) If I recall = correctly, they are about the same size as my throttle body bore. I = wonder if I will loose much efficiency as the air goes through the = corregated hose, and if the Van's RV ventillation NACA ducts will = provide a sufficient volume of air. Of course while flying, I would have = the advantage of a little bit of ram effect as well as the ability to = suck in fresh outside air that has not been heated inside the cowling = during taxi/takeoff run. Any opinions/suggestions would of course be = much appreciated. I will discuss the vapor lock issue in the next post, = so as to not complicate responses, etc. Thanks to all who reply. Paul = Conner =20 -------------------------------------------------------------------------= - No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: = 2/14/2005 -------------------------------------------------------------------------= - >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html -------------------------------------------------------------------------= --- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005 -------------------------------------------------------------------------= ----- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005 -------------------------------------------------------------------------= ----- >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_000_0023_01C5147B.673DE650 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Paul, I use a 3" dia SCAT tube which = undoubtedly=20 causes some loss of pressure, but much better than sucking in hot air = from under=20 the cowling.  I used to know a rule of thumb formula that told you = how much=20 power you lost for each 10F temp rise, I think it was 1% power loss for = each=20 10F.  If correct then with an OAT of say 60F , your = under-the-cowl air=20 temp could easily be 120F.  A 60 deg rise of temp =3D  6% = loss in=20 power.  So say you are making 162HP at 5600 on a 60F day.  You = put the=20 cowl on and the temps go to 120F, 6% of 162 =3D 9.72 HP loss or down to=20 150.28HP.
 
. 
 
My spreadsheet shows that a 9.72 HP = drop to=20 150.28HP would give you an rpm of  around 5150 - 5200. This sounds = fairly=20 consistent with what you are seeing, I believe.
 
With my cowl off my static might be = 5300 rpm=20 - with my cowling on with SCAT attached to the throttle body I get = at least=20 5600 rpm and perhaps 5800 on a cooler day. So I think say 7-9 HP is too = much to=20 give up to hot air.  Duct that sucker.
 
Ed A
----- Original Message -----
From:=20 Paul=20
Sent: Wednesday, February 16, = 2005 8:54=20 PM
Subject: [FlyRotary] Re: I = found the=20 power

Thanks, Ed....I think the results of = my=20 on-again-off-again cowl experiments pretty well proved this.  Do = you=20 think that SCAT or SCEET tubing (the one with the wire reinforcement,=20 whichever that one is) would create too much drag on the incoming = air? =20 Paul Conner
----- Original Message -----
From:=20 Ed Anderson
To: Rotary motors in = aircraft=20
Sent: Wednesday, February 16, = 2005 6:07=20 PM
Subject: [FlyRotary] Re: I = found the=20 power

Paul,
 
If you are not routing outside air = to your=20 engine intake, you are giving up power.  The less dense, hot = air=20 underneath the cowling will take 200-400 rpm away from your = rotary. =20 The NACA ducts should work well for this application.
 
Ed A
----- Original Message ----- =
From:=20 Paul
To: Rotary motors in = aircraft=20
Sent: Wednesday, February = 16, 2005=20 6:26 PM
Subject: [FlyRotary] I = found the=20 power

Today I finished installing the = firesleeve on=20 the remaing fuel lines, made some stand-offs so that the fuel = lines would=20 not be right up against the engine, and finished hooking up and = securing a=20 few other items. With the top cowling off,  I ran the = pumps for=20 a minute, then checked for leaks...none found.  Then I = started the=20 engine and ran it for 20 or so seconds and shut it down and = reinspected=20 for fuel leaks. None found.  I restarted and taxiied away = from the=20 hangar a bit so as to not be as loud for others in and near the = hangar and=20 did a full power runup.  I hit 5600 static rpm's. In the = past, the=20 best I could hope for was 5200, most of the time settling for 5100 = rpm's.  I taxiied back in and installed the top = cowling....max rpm's=20 5100.  Took the top cowling back off....max rpm's 5600.  = One=20 more try....5100 with the cowling back on.  It is beginning = to become=20 more clear to me, that one of two things are affecting = rpm's.  Option=20 one is that with the top cowling on the engine is ingesting heated = air and=20 just cannot develop the same power as when it ingests outside = unheated=20 air.  Option two is the muffler bearing may be worn.  = I'm kinda=20 leaning toward option one.
     I was = thinking of=20 installing two small NACA ducts on the bottom of my cowling with = two hoses=20 coming up to feed air to my TWM throttlebody.  The NACA ducts = I=20 purchased from Van's RV (made for cowling ventilation) already = have a male=20 outlet already molded in the assembly, so you just slide a hose = over it=20 and secure with a clamp. Very simple installation.(Works well for = my cabin=20 ventillation) If I recall correctly, they are about the same = size as=20 my throttle body bore. I wonder if I will loose much efficiency as = the air=20 goes through the corregated hose, and if the Van's RV ventillation = NACA=20 ducts will provide a sufficient volume of air. Of course while = flying, I=20 would have the advantage of a little bit of ram effect as well as = the=20 ability to suck in fresh outside air that has not been heated = inside the=20 cowling during taxi/takeoff run.  Any opinions/suggestions = would of=20 course be much appreciated.  I will discuss the vapor lock = issue in=20 the next post, so as to not complicate responses, etc.  = Thanks to all=20 who reply.  Paul Conner
   

No virus found in this outgoing message.
Checked by AVG=20 Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.8 - = Release Date:=20 2/14/2005

>>  Homepage: =20 http://www.flyrotary.com/
>>  Archive:  =20 = http://lancaironline.net/lists/flyrotary/List.html

No virus found in this incoming message.
Checked by AVG=20 Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.8 - Release = Date:=20 2/14/2005

No virus found in this outgoing message.
Checked by AVG=20 Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.8 - Release = Date:=20 2/14/2005

>>  Homepage: =20 http://www.flyrotary.com/
>>  Archive:  =20 = http://lancaironline.net/lists/flyrotary/List.html
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