X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 20 Jun 2005 21:34:56 -0400 Message-ID: X-Original-Return-Path: Received: from [64.4.35.175] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.3.4) with ESMTP id 1008315 for lml@lancaironline.net; Mon, 20 Jun 2005 21:25:06 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.4.35.175; envelope-from=gary21sn@hotmail.com Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Mon, 20 Jun 2005 18:24:21 -0700 X-Original-Message-ID: Received: from 71.34.249.53 by BAY12-DAV1.phx.gbl with DAV; Tue, 21 Jun 2005 01:24:20 +0000 X-Originating-IP: [71.34.249.53] X-Originating-Email: [gary21sn@hotmail.com] X-Sender: gary21sn@hotmail.com From: "Gary Edwards" X-Original-To: "Lancair Mailing List" Subject: Re: Induction air filter X-Original-Date: Mon, 20 Jun 2005 18:24:11 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0061_01C575C5.4162D390" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.10.0011.1703 Seal-Send-Time: Mon, 20 Jun 2005 18:24:11 -0700 X-OriginalArrivalTime: 21 Jun 2005 01:24:21.0107 (UTC) FILETIME=[F36D6430:01C575FF] This is a multi-part message in MIME format. ------=_NextPart_000_0061_01C575C5.4162D390 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable John Likewise, for the bird strike, I am hoping that the bird is large enough = to lodge in the cowl inlet, or up against the valve shaft, or if it is=20 small enough to pass through to the servo body, small enough to allow=20 enough airflow to make a safe landing. Sure, there is a size range that=20 will defeat the system. I always avoid that size bird :o) The real=20 small ones go through, and out the exhaust pipe. Then there is the guy=20 who was cutting toilet paper, and that clogged his intake, and he landed = dead stick (at the airport). A screen would help some of these cases, but then there is the=20 possibility of the screen getting ingested because it came loose, or got = knocked loose. Some of the no-filter guys use plastic screen to mitigate = this possibility. Scott I have only been worried about dirt filled air on take-off. This is a = solution to that problem. If a bird (or piece of one) can actually get = into my intake it will probably be sucked right through since it would = be so small - That is why it is safer to fly WOT. I am more worried = about spearing a bird with my pitot tube since it is not occasionally = protected by a fan blade. =20 Bill Actually, a bird has pretty good odds on getting to your air intake = without encountering a prop blade. The odds would be somewhere around 3 = 1/2 to 1 of success (although I'm sure that the bird wouldn't see it as = successful) depending on your speed, rpm and the size of the bird. At 180 knots, you're traveling about 18,216 feet per minute. At 2500 rpm = a blade is passing by the intake at the rate of 5,000 blades per minute = (for a two blade prop). That means that the airplane travels over 3 1/2 = feet between blade passes. A 1 foot long bird would have better than 3 = to 1 chance of getting through.=20 So what's it all mean, Mr. Natural? Uhhh, not much. Just that you = shouldn't count on your prop to mince avian airspace sharers into bite = size pieces. That's a nice design, John. And good info from all of you. I have the unfortunate experience of having been in the flight path of a = group of small birds. It occurred during takeoff at about 500' AGL out = of Salem, Oregon. One of them met its 'undoing' at my induction opening = of the bottom cowl. So, it did make it past the prop as Bill discussed. = =20 The flight went fine (I was not aware of the intake obstruction until = landing 1 hour later). My bird, that is, the one I sit in, has a metal = screen at the front of the carburetor air box which is about an inch in = from the cowl opening. There was a bird wing and some feathers stuck in = the screen. And there was a lot of 'goo' (bird parts) to clean up = around the intake opening on the bottom cowl. The souvenir feathers are = on the wall in my hanger. I am of the opinion that the intake screen = very well may have saved "my bacon". I occasionally think about the possible forced landing at an off-airport = location in the city (Salem airport is at the south end of the city and = my heading was north) had the bird obstruction caused an engine = stoppage. Gary Edwards LNC2 N21SN Medford, Oregon =20 ------=_NextPart_000_0061_01C575C5.4162D390 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
John
 
Likewise, for the bird strike, I am hoping that the bird is = large=20 enough
to lodge in the cowl inlet, or up against the valve shaft, or = if it=20 is
small enough to pass through to the servo body, small enough to = allow=20
enough airflow to make a safe landing. Sure, there is a size range = that=20
will defeat the system. I always avoid that size bird = :o)   The=20 real
small ones go through, and out the exhaust pipe. Then there is = the guy=20
who was cutting toilet paper, and that clogged his intake, and he = landed=20
dead stick (at the airport).

A screen would help some of = these cases,=20 but then there is the
possibility of the screen getting ingested = because it=20 came loose, or got
knocked loose. Some of the no-filter guys use = plastic=20 screen to mitigate
this possibility.
 
Scott
 
I have only been worried about dirt filled air on = take-off.  This=20 is a solution to that problem.  If a bird (or piece of one) can = actually=20 get into my intake it will probably be sucked right through since it = would be so=20 small - That is why it is safer to fly WOT.  I am more worried = about=20 spearing a bird with my pitot tube since it is not occasionally = protected by a=20 fan blade. 
 
 
Bill
 
Actually, a bird has pretty good odds on getting to your air = intake=20 without encountering a prop blade. The odds would be somewhere around 3 = 1/2 to 1=20 of success (although I'm sure that the bird wouldn't see it as = successful)=20 depending on your speed, rpm and the size of the bird.
 
At 180 knots, you're traveling about 18,216 feet per minute. At = 2500=20 rpm a blade is passing by the intake at the rate of 5,000 blades per = minute (for=20 a two blade prop). That means that the airplane travels over 3 1/2 feet = between=20 blade passes. A 1 foot long bird would have better than 3 to 1 = chance=20 of getting through.
 
So what's it all mean, Mr. Natural?  Uhhh, not much. Just = that you=20 shouldn't count on your prop to mince avian airspace sharers into = bite size=20 pieces.
 
That's a nice design, John.  And good info from all of = you.
 
I have the unfortunate experience of having been in the flight path = of a=20 group of small birds.  It occurred during takeoff at about 500' AGL = out of=20 Salem, Oregon.  One of them met its 'undoing' at my induction = opening=20 of the bottom cowl.  So, it did make it past the prop as Bill=20 discussed. 
 
The flight went fine (I was not aware of the intake obstruction = until=20 landing 1 hour later).  My bird, that is, the one I sit = in, has a=20 metal screen at the front of the carburetor air box which is about an = inch in=20 from the cowl opening.  There was a bird wing and some = feathers stuck=20 in the screen.  And there was a lot of 'goo' (bird parts) to clean = up=20 around the intake opening on the bottom cowl.  The souvenir = feathers=20 are on the wall in my hanger.  I am of the opinion that the = intake=20 screen very well may have saved "my bacon".
 
I occasionally think about the possible forced landing at=20 an off-airport location in the city (Salem airport is at the = south end=20 of the city and my heading was north) had the bird obstruction = caused an=20 engine stoppage.
 
Gary Edwards
LNC2 N21SN
Medford, Oregon     
 
------=_NextPart_000_0061_01C575C5.4162D390--