X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-lb0-f171.google.com ([209.85.217.171] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTPS id 6363121 for flyrotary@lancaironline.net; Sat, 06 Jul 2013 21:41:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.217.171; envelope-from=alex.molteno@gmail.com Received: by mail-lb0-f171.google.com with SMTP id 13so2885870lba.16 for ; Sat, 06 Jul 2013 18:40:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=blGPKZ6yFIlXjCxo0TlCFg6LNeCRl6EE20VPgHylqgg=; b=AH1XV0L3oWa0EoDt28P8SRwCZiES6MiGClBhB6r16036xA2TI6tDOFQTeMExauF2AQ TgHKBbuS7oBFQDGkBYlUdx/dAEOu9hBlrzfAtj7u5dIdeCpSaWkOX814sfNrZUZPbFgL 6YdrYdDs1rWpXQYw9RE+XQKVFxZNKJBu1JKD7U1kwC9+p2wSVCmSKYG2h4rs1YfXfBxI bpqiphM2XgY8GJHhjSec47k41FCQ2OFfmnkFLmVwAuDCWFvY8cDFa63X6jVlkv6QvNwA otCnU7Fi6UuNFkvsxcCBfaOU4/jHE4a+qA9bPrra3X1VOpD2JbqXGfMktlfcvSQH3/L7 C3/A== MIME-Version: 1.0 X-Received: by 10.152.6.4 with SMTP id w4mr7788115law.14.1373161259391; Sat, 06 Jul 2013 18:40:59 -0700 (PDT) Received: by 10.112.13.195 with HTTP; Sat, 6 Jul 2013 18:40:59 -0700 (PDT) In-Reply-To: References: Date: Sun, 7 Jul 2013 02:40:59 +0100 Message-ID: Subject: Re: [FlyRotary] Re: Ram Air and filters From: alex To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=089e0149421a15e35304e0e205ae --089e0149421a15e35304e0e205ae Content-Type: text/plain; charset=ISO-8859-1 Ya don't want to pay the fuel or maintenance on anything burning kerosene..I take your point on less airflow. Can you tell me which pressure is greater in the intake manifold, the influence of ram air pressure or intake vacuum pressure. Or does it vary from one to the other according to the cycle. For an "automatic" homegrown system on a 2 rotor would it work to have a spring loaded door opening inward into the intake manifold, fed by interior cowling air when the main system is blocked. It makes sense to me to have a door open for a negative pressure in the intake manifold which i imagine would be the case of a blocked regular air intake and ongoing intake vacuum pressure. Would a door like this be kept shut under normal conditions of positive ram air, to preserve ram air which is what we want? Alex M On Sun, Jul 7, 2013 at 12:08 AM, wrote: > ** > 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 > > --089e0149421a15e35304e0e205ae Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Ya don't want to pay the fuel or maintenance on anything burning kerose= ne..I take your point on less airflow. Can you tell me which pressure is gr= eater in the intake manifold, the influence of ram air pressure or intake v= acuum pressure. Or does it vary from one to the other according to the cycl= e.=A0

For an "automatic" homegrown system on a 2 rotor w= ould it work to have a spring loaded door opening inward into the intake ma= nifold, fed by interior cowling air when the main system is blocked. It mak= es sense to me to have a door open for a negative pressure in the intake ma= nifold which i imagine would be the case of a blocked regular air intake an= d ongoing intake vacuum pressure. Would a door like this be kept shut under= normal conditions of positive ram air, to preserve ram air which is what w= e want?

Alex M

On S= un, Jul 7, 2013 at 12:08 AM, <ARGOLDMAN@aol.com> wrote:
=
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.
=A0
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
=A0
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.
=A0
Would that we could all fly Turboprops
=A0
Rich
=A0
In a message dated 7/6/2013 1:12:11 P.M. Central Daylight Time,=20 alex.molteno@gm= ail.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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