Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 884152 for flyrotary@lancaironline.net; Tue, 19 Apr 2005 20:49:38 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.res.rr.com [24.74.185.127]) by ms-smtp-04-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j3K0mjL5011721 for ; Tue, 19 Apr 2005 20:48:50 -0400 (EDT) Message-ID: <002401c54542$b688bda0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Area calcuation for Cone air filters was [FlyRotary] Re: Air filters Date: Tue, 19 Apr 2005 20:48:46 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0021_01C54521.2E96F6D0" 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_0021_01C54521.2E96F6D0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Tuesday, April 19, 2005 7:59 PM Subject: [FlyRotary] Re: Area calcuation for Cone air filters was = [FlyRotary] Re: Air filters 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 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 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 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 Well, you could be correct about that - but they do not explicitedly = state that fact. However, since they do infer that you should look for = one of their filters of comparable area - I can understand someone = viewing it that way. But then they nowhere give you the filter area of = their filters (at least not the cone ones). I'll blame it on Jerry for = bring the accordion pleats to my attention {:>) Anyhow, you's gots your choice, The formula first computes the area = of the truncated cone, if you feel that already has the factor of x4 in = it then you get their area and can disregard the X4 multiplication I do. 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 Sounds reasonable to me Rusty. In anycase, I think this gives you a = somewhat better idea than a wide A__ guess {:>) 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 You are undoubtedly correct, Rusty, but I think we are the point of = marking with a paint brush and cutting with a chain saw. This should = put you close enough. 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 I'm looking at a filter made by S&B, they have a base which is shaped = more like a funnel than a square end which should help the air turn = better from the filter to the intake. Its call Absolute Air Flow AAF = and is used with the cone type filters. Ed A Rusty (almost deleted this since it was getting out of control) ------=_NextPart_000_0021_01C54521.2E96F6D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Tuesday, April 19, 2005 = 7:59=20 PM
Subject: [FlyRotary] Re: Area = calcuation=20 for Cone air filters was [FlyRotary] Re: Air filters

Rusty, some of the cones have = an opening on=20 the intake in and another smaller cone that is inside the large cone = for=20 increased filtering area.  They don't specify the dimensions of = this=20 inner cone so I conservatively just make it 10% of the total filter = area of=20 the larger 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=20 square 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=20 more 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 to be the same thickness by eliminating that parameter.  = From=20 that standpoint, I think you can drop the X4 factor = to estimate the=20 pleat area, because they've already built that into = their recommended=20 area formula.  
 
Well, you could be correct about that - but = they do=20 not explicitedly state that fact.  However, since they do infer = that you=20 should look for one of their filters of comparable area - I can = understand=20 someone viewing it that way.  But then they nowhere give you the = filter=20 area of their filters (at least not the cone ones).  I'll blame = it on=20 Jerry for bring the accordion pleats to my attention=20 {:>)
 
Anyhow, you's gots your choice,  The = formula=20 first computes the area of the truncated cone, if you feel that = already has=20 the factor of x4 in it then you get their area and can disregard the = X4=20 multiplication I do.
 
 
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=20 compare to their formula.  This would be assuming that you have = one of=20 their more normal filters that doesn't have the end open. =20
 
Sounds reasonable to me Rusty.  In = anycase, I=20 think this gives you a somewhat better idea than a wide A__ guess=20 {:>)
 
Back to the filter I had mentioned, 4.5 = base x 3.5=20 top x 5.75 length.  In their sizing info, it appears that they = want you=20 to reduce the height by .75", because the ends of the filter are = sealed in=20 rubber, and don't pass any air.  That makes my example 5" = tall. =20 using those numbers, I get 63 sq in for filter area.  Since I = will run=20 7500, that makes the requirement 57 sq in, rather than 53.   = Sounds=20 like it will still work up to about 8200 rpm, which should be = sufficient=20 :-)  
 
You are undoubtedly correct, Rusty, but I = think we=20 are the point of marking with a paint brush and cutting with a chain=20 saw.  This should put you close = enough.
 
Heck, I'll order one and see how it = works.  Easy=20 to test on the ground before going to the trouble of making=20 a box for it to live in.     
 
I'm = looking at a=20 filter made by S&B, they have a base which is shaped more like a = funnel=20 than a square end which should help the air turn better from the = filter to the=20 intake.  Its call Absolute Air Flow  AAF and is used with = the cone=20 type filters.
 
Ed A
 
 
Rusty=20 (almost deleted this since it was getting out of=20 control) 
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