X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 20 Jun 2011 08:00:14 -0400 Message-ID: X-Original-Return-Path: Received: from imr-da02.mx.aol.com ([205.188.105.144] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with ESMTP id 5025489 for lml@lancaironline.net; Sun, 19 Jun 2011 20:46:18 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.144; envelope-from=Sky2high@aol.com Received: from imo-da01.mx.aol.com (imo-da01.mx.aol.com [205.188.169.199]) by imr-da02.mx.aol.com (8.14.1/8.14.1) with ESMTP id p5K0jeah029332 for ; Sun, 19 Jun 2011 20:45:40 -0400 Received: from Sky2high@aol.com by imo-da01.mx.aol.com (mail_out_v42.9.) id q.1271.340155 (56011) for ; Sun, 19 Jun 2011 20:45:39 -0400 (EDT) Received: from magic-m27.mail.aol.com (magic-m27.mail.aol.com [172.20.22.200]) by cia-md07.mx.aol.com (v129.10) with ESMTP id MAILCIAMD075-dacb4dfe98335f; Sun, 19 Jun 2011 20:45:39 -0400 From: Sky2high@aol.com X-Original-Message-ID: <24d58.5f07de1f.3b2ff233@aol.com> X-Original-Date: Sun, 19 Jun 2011 20:45:39 EDT Subject: Re: [LML] Full feathering prop X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_24d58.5f07de1f.3b2ff233_boundary" X-Mailer: AOL 9.6 sub 5004 X-AOL-IP: 24.15.17.119 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com --part1_24d58.5f07de1f.3b2ff233_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Dan, You are almost right. Feathering prop and counterweighted prop may do as you say. The more simple Hartzell prop controlled by oil pressure will go to flat pitch without oil pressure as when the engine stops running. So, the real problem is when the engine stops producing power but has oil and does not seize. The wind milling prop may provide sufficient pressure to allow you to pull it back to coarse pitch and still keep it rotating enough to stay in the coarse pitch condition. Otherwise, try to get it to stop. Hartzell CS prop (non feathering, no counterweights): Prop control forward = high rpm = flat pitch = lo oil pressure. Prop control back = low rpm = coarse pitch = high oil pressure. Grayhawk In a message dated 6/19/2011 6:56:36 P.M. Central Daylight Time, dballin@gmail.com writes: One point about terminology. There is a difference between full feathering props and counterweighted props. When oil pressure drops, both go to low RPM (coarse pitch), but full feathering will obviously go into full feather position and counterweighted goes close. Full feathering need an accumulator (read extra weight complexity) to get out of feather were counterweighted will generally windmill. The interesting thing ( and I only have what I have been told) is that the difference in drag/glide performance is not that significant. I wanted a counterweighted prop so when the engine quit it would go to best glide configuration without my input. I ended up with an MT because of weight and at the time Hartzel didn't have a spinner that would fit the Legacy. I think the down side is the issue raised that if the engine is still running and the oil pressure is low, the prop will go to coarse pitch - not the best, say on take off. The other issue is that I think with training, one can get the prop lever back to low RPM fairly quickly. Counterweights do increase weight and cost so is it worth it? Not sure. Like everything else, this is a compromise and you just need to know the correct procedures for your install. Dan N386DM hopefully flying this summer -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html --part1_24d58.5f07de1f.3b2ff233_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Dan,

You are almost right.

Feathering prop and counterweighted prop may do as you say.

The more simple Hartzell prop controlled by oil pressure will go to= flat=20 pitch without oil pressure as when the engine stops running. So= , the=20 real problem is when the engine stops producing power but has oil and= does=20 not seize. The wind milling prop may provide sufficient pressure to= allow=20 you to pull it back to coarse pitch and still keep it rotating enough to= stay in=20 the coarse pitch condition. Otherwise, try to get it to stop.

Hartzell CS prop (non feathering, no counterweights): Prop control fo= rward=20 =3D high rpm =3D flat pitch =3D lo oil pressure. Prop control back= =3D low rpm =3D=20 coarse pitch =3D high oil pressure.

Grayhawk

In a message dated 6/19/2011 6:56:36 P.M. Central Daylight Time,=20 dballin@gmail.com writes:

One=20 point about terminology. There is a difference between=20 full
feathering props and counterweighted props. When oil press= ure=20 drops,
both go to low RPM (coarse pitch), but full feathering will=20 obviously
go into full feather position and counterweighted goes=20 close. Full
feathering need an accumulator (read extra weight= =20 complexity) to get
out of feather were counterweighted will generally= =20 windmill. The
interesting thing ( and I only have what I have= been=20 told) is that the
difference in drag/glide performance is not that=20 significant.

I wanted a counterweighted prop so when the engine= quit it=20 would go to
best glide configuration without my input. I ended= up=20 with an MT
because of weight and at the time Hartzel didn't have a sp= inner=20 that
would fit the Legacy. I think the down side is the issue= raised=20 that
if the engine is still running and the oil pressure is low, the= =20 prop
will go to coarse pitch - not the best, say on take off. = The=20 other
issue is that I think with training, one can get the prop lever= =20 back
to low RPM fairly quickly. Counterweights do increase weig= ht and=20 cost
so is it worth it? Not sure.

Like everything else,= this=20 is a compromise and you just need to know
the correct procedures for= your=20 install.

Dan
N386DM
hopefully flying this summer

--<= BR>For=20 archives and unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html

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