Return-Path: <13brv3@bellsouth.net> Received: from imf25aec.mail.bellsouth.net ([205.152.59.73] verified) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 884104 for flyrotary@lancaironline.net; Tue, 19 Apr 2005 19:59:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.73; envelope-from=13brv3@bellsouth.net Received: from ibm71aec.bellsouth.net ([65.6.194.9]) by imf25aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20050419235846.HJZP22125.imf25aec.mail.bellsouth.net@ibm71aec.bellsouth.net> for ; Tue, 19 Apr 2005 19:58:46 -0400 Received: from rd ([65.6.194.9]) by ibm71aec.bellsouth.net (InterMail vG.1.02.00.01 201-2136-104-101-20040929) with ESMTP id <20050419235844.VADD1909.ibm71aec.bellsouth.net@rd> for ; Tue, 19 Apr 2005 19:58:44 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Area calcuation for Cone air filters was [FlyRotary] Re: Air filters Date: Tue, 19 Apr 2005 18:59:06 -0500 Message-ID: <05c101c5453b$c5a3a3b0$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_05C2_01C54511.DCCD9BB0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_05C2_01C54511.DCCD9BB0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Rusty, some of the cones have an opening on the intake in and another smaller cone that is inside the large cone for increased filtering area. They don't specify the dimensions of this inner cone so I conservatively just make it 10% of the total filter area of the larger cone.=20 =20 That makes sense Ed. I later saw what they called an inverted top that = had that sort of arrangement. With the size I could use, I don't think = there could be much of an inside cone. =20 =20 That filter should give you approx 352 square inches of filter space. = For a 13B at 7000 rpm K&N area calculation says 53 sq inches is sufficient, = so yes, I think I can safely say you have more than enough filter area. So thats good as it will give more filtering and less airflow obstruction.=20 =20 I have to admit that I'm still having trouble with your spreadsheet. = When you calculate 53 sq inches using their formula, this seems to indicate = that you need 53 sq in of "filter element" surface area. It looks like = they're assuming all their filter elements to be the same thickness by = eliminating that parameter. From that standpoint, I think you can drop the X4 = factor to estimate the pleat area, because they've already built that into their recommended area formula. =20 =20 If all we care about is the filter element surface area, then your = "filter area" (i15) seems to give the number we need to compare to their = formula. This would be assuming that you have one of their more normal filters = that doesn't have the end open. =20 =20 Back to the filter I had mentioned, 4.5 base x 3.5 top x 5.75 length. = In their sizing info, it appears that they want you to reduce the height by .75", because the ends of the filter are sealed in rubber, and don't = pass any air. That makes my example 5" tall. using those numbers, I get 63 = sq in for filter area. Since I will run 7500, that makes the requirement = 57 sq in, rather than 53. Sounds like it will still work up to about 8200 = rpm, which should be sufficient :-) =20 =20 Heck, I'll order one and see how it works. Easy to test on the ground before going to the trouble of making a box for it to live in. =20 =20 Rusty (almost deleted this since it was getting out of control)=20 ------=_NextPart_000_05C2_01C54511.DCCD9BB0 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Message
Rusty, some of the cones have an = opening on=20 the intake in and another smaller cone that is inside the large cone for = increased filtering area.  They don't specify the dimensions of = this inner=20 cone so I conservatively just make it 10% of the total filter area of = the larger=20 cone. 
 
That makes sense Ed.  I later = saw what they=20 called an inverted top that had that sort of = arrangement.  With=20 the size I could use, I don't think there could be much of an = inside=20 cone.     
 
That filter should give you = approx 352 square=20 inches of  filter space.  For a 13B at 7000 rpm K&N area=20 calculation says 53 sq inches is sufficient, so yes, I think I can = safely say=20 you have more than enough filter area.  So thats good as it will = give more=20 filtering and less airflow obstruction. 
 
I have to admit that I'm still having trouble = with your=20 spreadsheet.  When you calculate 53 sq inches using their = formula,=20 this seems to indicate that you need 53 sq in of "filter element" = surface=20 area.   It looks like they're assuming all their filter = elements=20 to be the same thickness by eliminating that parameter.  From that=20 standpoint, I think you can drop the X4 factor to estimate the = pleat=20 area, because they've already built that into their recommended = area=20 formula.  
 
If all we care about is the filter element = surface=20 area, then your "filter area" (i15) seems to give the number we need to = compare=20 to their formula.  This would be assuming that you have one of = their more=20 normal filters that doesn't have the end open.  =
 
Back to the filter I had mentioned, 4.5 base = x 3.5 top=20 x 5.75 length.  In their sizing info, it appears that they want you = to=20 reduce the height by .75", because the ends of the filter are sealed in = rubber,=20 and don't pass any air.  That makes my example 5" tall.  using = those=20 numbers, I get 63 sq in for filter area.  Since I will run 7500, = that makes=20 the requirement 57 sq in, rather than 53.   Sounds like it = will still=20 work up to about 8200 rpm, which should be sufficient=20 :-)  
 
Heck, I'll order one and see how it = works.  Easy=20 to test on the ground before going to the trouble of making = a box=20 for it to live in.     
 
Rusty (almost=20 deleted this since it was getting out of=20 control) 
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