X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from omr-m06.mx.aol.com ([64.12.143.80] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTPS id 6363039 for flyrotary@lancaironline.net; Sat, 06 Jul 2013 19:08:49 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.143.80; envelope-from=ARGOLDMAN@aol.com Received: from mtaomg-ma04.r1000.mx.aol.com (mtaomg-ma04.r1000.mx.aol.com [172.29.41.11]) by omr-m06.mx.aol.com (Outbound Mail Relay) with ESMTP id 96E9D700000B5 for ; Sat, 6 Jul 2013 19:08:16 -0400 (EDT) Received: from core-dse003a.r1000.mail.aol.com (core-dse003.r1000.mail.aol.com [172.29.227.201]) by mtaomg-ma04.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id 5C28BE000082 for ; Sat, 6 Jul 2013 19:08:16 -0400 (EDT) From: ARGOLDMAN@aol.com Full-name: ARGOLDMAN Message-ID: <8b137.377a1d6.3f09fd60@aol.com> Date: Sat, 6 Jul 2013 19:08:16 -0400 (EDT) Subject: Re: [FlyRotary] Re: Ram Air and filters To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_8b137.377a1d6.3f09fd60_boundary" X-Mailer: AOL 9.6 sub 5004 X-Originating-IP: [67.184.50.137] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1373152096; bh=Cu46wQUyqsVQxJXHGu6bXehTTLZoZcAfWh3S0IOj3uY=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=TADAwoVCZsv3gK3sMZA4pzgk3eTkOHU6qX4cWeRzytgt5UYj6IppIabuQW2YVrRab LSmvpVQ21cnXV6IwmPP+0+4VPpAWlM2Bwq4wK0vwuNNiysxupF4qV1x98QMqACe3qw aEWyUcKdi9es4Rs4S/PCbuon+eo2LQV+nOKJGHho= X-AOL-SCOLL-SCORE: 0:2:343743360:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d290b51d8a3604346 --part1_8b137.377a1d6.3f09fd60_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Interesting concept, I can see how that would eliminate a lot of FOD, however that is not how alternate air systems work for piston/rotor type engines. That is almost the reverse. My guess is that the airflow in the PT6 is hughly greater than in a 2 or 3 rotor engine and the kinetic energy of the FOD is significantly less. Additionally, the alternate air is to allow air to flow if the induction system gets blocked. this valve works in the reverse. The greater the pressure upstream the more it will open and in fact will vent the presure (FOD/rain etc) overboard If the intake becomes blocked as in a filter or induction icing, the pressure is reduced tending to seal the manifold.at this valve. Would that we could all fly Turboprops Rich In a message dated 7/6/2013 1:12:11 P.M. Central Daylight Time, alex.molteno@gmail.com writes: Hello Lynn Are you referring to a similar system you see on the Pratt and Whitney PT6 series engine, basically reversing the flow of air 180 degrees before entering the compressor (throttle body for us i guess). The inertia of the FOD or ice particles doesn't let them "make the turn" into the throttle body and they exit the duct via a bypass flap. In this case the opening of the flap creates the 180 degree turn and spillover air exit? Alex M --part1_8b137.377a1d6.3f09fd60_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Interesting concept, I can see how that would eliminate a lot of FOD,= =20 however that is not how alternate air systems work for piston/rotor type=20 engines.
 
That is almost the reverse. My guess is that the airflow in the PT6 is= =20 hughly greater than in a 2 or 3 rotor engine and the kinetic energy of the = FOD=20 is significantly less. Additionally, the alternate air is to allow air to f= low=20 if the induction system gets blocked. this valve works in the reverse. The= =20 greater the pressure upstream the more it will open and in fact will vent t= he=20 presure (FOD/rain etc) overboard
 
If the intake becomes blocked as in a filter or induction icing, the= =20 pressure is reduced tending to seal the manifold.at this valve.
 
Would that we could all fly Turboprops
 
Rich
 
In a message dated 7/6/2013 1:12:11 P.M. Central Daylight Time,=20 alex.molteno@gmail.com writes:
= Hello=20 Lynn=20

Are you referring to a similar system you see on the Pratt and Whitn= ey=20 PT6 series engine, basically reversing the flow of air 180 degrees before= =20 entering the compressor (throttle body for us i guess). The inertia of th= e FOD=20 or ice particles doesn't let them "make the turn" into the throttle body = and=20 they exit the duct via a bypass flap. In this case the opening of the fla= p=20 creates the 180 degree turn and spillover air exit?

Alex M

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