X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 20 Aug 2013 15:45:38 -0400 Message-ID: X-Original-Return-Path: Received: from qmta01.westchester.pa.mail.comcast.net ([76.96.62.16] verified) by logan.com (CommuniGate Pro SMTP 6.0.6) with ESMTP id 6433879 for lml@lancaironline.net; Tue, 20 Aug 2013 08:06:42 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.62.16; envelope-from=jmorgan1023@comcast.net Received: from omta09.westchester.pa.mail.comcast.net ([76.96.62.20]) by qmta01.westchester.pa.mail.comcast.net with comcast id Ezta1m0010SCNGk5106A3b; Tue, 20 Aug 2013 12:06:10 +0000 Received: from [192.168.1.102] ([24.11.157.196]) by omta09.westchester.pa.mail.comcast.net with comcast id F0691m00Y4EXR5U3V06AWA; Tue, 20 Aug 2013 12:06:10 +0000 From: Jack Morgan Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: multipart/alternative; boundary="Apple-Mail=_E5575877-11C1-43EA-88B2-E50F0D4BDB46" Subject: Prop governor's X-Original-Date: Tue, 20 Aug 2013 08:06:12 -0400 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1283) --Apple-Mail=_E5575877-11C1-43EA-88B2-E50F0D4BDB46 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 Adding to Robert's correct comments below, both the MT and Hartzell = governors control engine RPM using a centrifugal weight type RPM sensing = device. This technique changes the oil pressure supplied to the prop = depending on engine RPM only. The system works the same regardless if = the engine or the propeller is driving the crankshaft rotation as long = as oil pressure is being produced by the rotation. If oil pressure fails, standard CS props are driven flat by the relative = wind while aerobatic props have counter weights mounted on the blades = themselves which drive them to full course. The aerobatic governors = control oil pressure opposite normal governors...... more pressure gives = flatter pitch. This change is required for aerobatics so a temporary = loss of oil pressure won't allow the engine to overspeed under high = power. Hope this helps clear up the confusion below. Jack Morgan On Aug 20, 2013, at 6:00 AM, Lancair Mailing List wrote: > From: Robert R Pastusek > Subject: RE: [LML] Re: Fw: [LML] Re: FW: [LML] Flaps on take-off? > Date: August 19, 2013 5:17:41 PM EDT > To: Lancair Mailing List >=20 >=20 > Wolfgang,=20 > My MT prop/governor does not work as you describe below. Specifically, = if the engine is turning (with oil pressure), I can control RPM within = the mechanical stop limits built into the prop hub, and total = power/drag. Idle power/min RPM/120 KIAS glide gives me 600-650 RPM; Max = RPM in that configuration gives about 2600 RPM, and the drag increase is = significant. At a bit above idle power, max RPM is limited to 2700 by = the governor, all the way up to max power. Min RPM is maintained as = power is added=85for a while=85but I=92ve never gone much above idle = power. with the prop at min RPM=85hard on the engine=85and it=92s not a = useful datapoint, but I suspect it will maintain 650 RPM through full = power?? >=20 > Bob > =20 > From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of = Wolfgang > Sent: Monday, August 19, 2013 12:40 PM > To: lml@lancaironline.net > Subject: [LML] Re: Fw: [LML] Re: FW: [LML] Flaps on take-off? > =20 > Where did the 320 and 172 information come from ? > =20 > Fixed pitch props will continue to windmill but what about constant = speed ? - - I haven't tried this with a non-responsive, non seized = engine. > =20 > The next question is what is the blade angle, resulting from a wind = driven constant speed propeller, for the "max" rpm and "min" rpm lever = positions. > =20 > The control loop gain will be "adverse" in that scenario (wind driven = vs shaft driven). > . . . in the wind driven mode - as the rpm decreases - the pitch is = made to go flatter - making the rpm decrease more - - - > =20 > After consulting with H&S Prop Shop here in Michigan, the light goes = on. > It does not matter where the RPM lever is set. > With a non-responsive engine, the blades will go to the minimum pitch = set by the physical stop in the prop hub, > . . . typically 10-15 degrees depending on setup for the particular = installation. > =20 > Now a feathering prop is a different ball game . . . > =20 >=20 --Apple-Mail=_E5575877-11C1-43EA-88B2-E50F0D4BDB46 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252
From: Robert R Pastusek = <Subject: RE: [LML] Re: = Fw: [LML] Re: FW: [LML] Flaps on take-off?
Date: August 19, 2013 = 5:17:41 PM EDT
To: Lancair Mailing = List <
Wolfgang, 
My MT prop/governor = does not work as you describe below. Specifically, if the engine is = turning (with oil pressure), I can control RPM within the mechanical = stop limits built into the prop hub, and total power/drag. Idle = power/min RPM/120 KIAS glide gives me 600-650 RPM; Max RPM in that = configuration gives about 2600 RPM, and the drag increase is = significant.  At a bit = above idle power, max RPM is limited to 2700 by the governor, all the = way up to max power. Min RPM is maintained as power is added=85for a = while=85but I=92ve never gone much above idle power. with the prop at = min RPM=85hard on the engine=85and it=92s not a useful datapoint, but I suspect it will maintain 650 = RPM through full power??

Bob

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