X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 16 Oct 2007 18:52:24 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-galgo.atl.sa.earthlink.net ([209.86.89.61] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2390476 for lml@lancaironline.net; Tue, 16 Oct 2007 17:38:38 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.61; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=D7MygF0voVmWAZ85tfVKfZXwdbo6AYZEKscGSa8Z15ZXJcmkMfxpfqF4mLVwJUlT; h=Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-ELNK-Trace:X-Originating-IP; Received: from [216.57.118.66] (helo=ccaselt2) by elasmtp-galgo.atl.sa.earthlink.net with asmtp (Exim 4.34) id 1Ihu6y-0006xv-UR for lml@lancaironline.net; Tue, 16 Oct 2007 17:38:01 -0400 X-Original-Message-ID: <027501c8103c$d9af0fb0$0302a8c0@nvidia.com> From: "Colyn Case on earthlink" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: prop drag X-Original-Date: Tue, 16 Oct 2007 17:38:10 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0272_01C8101B.51E7B440" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da9407e4c01bd9406f5559803935b0c98901e350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 216.57.118.66 This is a multi-part message in MIME format. ------=_NextPart_000_0272_01C8101B.51E7B440 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable > I'm considering a feathering prop but I've never used one. What = happens=20 > at startup and low RPM's- is there a control detent to prevent the = prop=20 > from going feathered? -Bill Wade Bill, there's no detent in the control. I am not an expert so I'm = posting this so some prop expert can correct me.... once you set the rpm below some threshold, I've been told it's going to = keep going toward full feathered. I've been told this happens about = 1900 rpm.=20 There is, however, a detent in the mechanism. If the govenor setting is = above some threshold, the prop is locked in a fine position as the rpm = falls through about 1200 rpm. Therefore you have to be above that rpm = when you command full feather or it won't. The Hartzell I have, will not unfeather without power. With a strong = battery you can crank it for a long time ( > 20 seconds) to get enough = oil pressure to change the pitch back to fine. This was empiracally = tested on one plane I know of. So as I see it, the situation relative to full feathering props is: pro: automatically goes to feather on engine out pro: (or con depending) hub is heavier than stock so it moves your cg = forward pro: excellent gliding range from high altitude con: goes to feather on low oil pressure, even if the engine is still = making power con: harder to restart in the air if it feathered because of lo oil = passure con: the hartzell version I have is metal so that is a rougher ride. ------=_NextPart_000_0272_01C8101B.51E7B440 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

> I'm considering a feathering = prop but=20 I've never used one. What happens
> at startup and low RPM's- is = there a=20 control detent to prevent the prop
> from going feathered? = -Bill=20 Wade

Bill, there's no detent in the=20 control. I am not an expert so I'm posting this so = some=20 prop expert can correct me....

once you set the rpm below some = threshold, I've=20 been told it's going to keep going toward full feathered. = I've been=20 told this happens about 1900 rpm.

There is, however, a detent in the = mechanism. =20 If the govenor setting is above some threshold, the prop is locked in a = fine=20 position as the rpm falls through about 1200 rpm. Therefore = you have=20 to be above that rpm when you command full feather or it = won't.

The Hartzell I have, will not unfeather = without=20 power. With a strong battery you can crank it for a = long time=20 ( > 20 seconds) to get enough oil pressure to change the pitch = back to=20 fine. This was empiracally tested on one plane I know=20 of.

So as I see it, the situation relative = to full=20 feathering props is:

pro: automatically goes to feather on = engine=20 out

pro: (or con depending) hub is heavier = than stock=20 so it moves your cg forward

pro: excellent gliding range from high=20 altitude

con: goes to feather on low oil = pressure, even if=20 the engine is still making power

con: harder to restart in the air if it = feathered=20 because of lo oil passure

con: the hartzell version I have is = metal so that=20 is a rougher ride.

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