X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 21 Aug 2013 12:46:54 -0400 Message-ID: X-Original-Return-Path: Received: from nm4-vm1.bullet.mail.ne1.yahoo.com ([98.138.91.44] verified) by logan.com (CommuniGate Pro SMTP 6.0.6) with ESMTPS id 6435790 for lml@lancaironline.net; Wed, 21 Aug 2013 10:34:45 -0400 Received-SPF: none receiver=logan.com; client-ip=98.138.91.44; envelope-from=casey.gary@yahoo.com Received: from [98.138.90.55] by nm4.bullet.mail.ne1.yahoo.com with NNFMP; 21 Aug 2013 14:34:09 -0000 Received: from [98.138.87.6] by tm8.bullet.mail.ne1.yahoo.com with NNFMP; 21 Aug 2013 14:34:09 -0000 Received: from [127.0.0.1] by omp1006.mail.ne1.yahoo.com with NNFMP; 21 Aug 2013 14:34:09 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 892002.56579.bm@omp1006.mail.ne1.yahoo.com Received: (qmail 76832 invoked by uid 60001); 21 Aug 2013 14:34:09 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Rocket-MIMEInfo:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=y66+Ok09NRuhM8hQyGRJ96W8vB2YB0/pT5UQMubwH5WEg2A+SNSomo3MH8RFMNUna4BJT/s7vIaJLKEAKtnoQzZ8nDLt6vCGVha/JdzZfcNXGuULulrxUsxqSEzXQYLjzI44nW5koOOw10mKAtPVHO3HTrDxG1ab0D9W8njl7Mo=; X-YMail-OSG: 1mTcKnMVM1mRsxIMISgzGtan8cxQDCQ_7xsBPg_OhzcizIh 8Z2NlgZ58h6mgSQe.SyDo7zuYvtkgWqKcoY.vCRYQHSaMpqFOu2HX..Ju7zM R3DwwdkRNcJW280F0E8gO7jl_XK0RZnOseYYb80DMinhBA_Yd46lTwkZPpAY 0xxcZlSm3ev15gjWW8AYUVpa74YLeSJxxBpn_ryRsqhdS9L9vDxyNUcwZWyB 0T_x4TlClaP5s5yfnA6MxBljNxi2xXm8ptajSzT_UkdIqWWJRebvYcG4jIz5 Oh3Ayl623GqJJYpgE_uSRT_T.YSvdJYk5J_ITFlzzCoiAp9UH6DbE8.r.hDq Bvwd.c08f3l.JJg6VrQQjGpylO4nG0eRf5x9SarBhXjMlRMgo44l9rjezrAp xE9UeizYHiJmlTnnTxzZTpWv6oDSCv_J56.mMLyHtSYa6gYlTjgct3YofJ.W lMDhqjCc8egKlV37lM_MpRyQRdb6VwXBQzbS.M5lI.zm6_IiLeuJzVIh0T00 yBgCOILxVJIExd8ASJ6sFmvc1g4YDXZkMjRwiOwCxCIItPNKOjR_1BdnsyH8 kCkoTzVSQgX07WyJeLk5SvqSjvGyK34R39plZlFfsxnzJXQ-- Received: from [97.92.63.83] by web120101.mail.ne1.yahoo.com via HTTP; Wed, 21 Aug 2013 07:34:09 PDT X-Rocket-MIMEInfo: 002.001,SSBndWVzcyBJJ2xsIGp1bXAgaW4gaGVyZSwgYnV0IG15IGNvbW1lbnRzIG1pZ2h0IG5vdCBiZSB3b3J0aCAyIGNlbnRzIDotKQoKVGhlIG9yaWdpbmFsIHF1ZXN0aW9uIHdhcyBhYm91dCB3aGV0aGVyIHRvIHVzZSBmbGFwcyBvbiB0YWtlb2ZmLCBhbmQgbGlrZSBtb3N0IHRoaW5ncywgaXQgaXMgYSBjb21wcm9taXNlLiDCoEEgbG9naWNhbCBvYmplY3RpdmUgbWlnaHQgYmUgdG8gZ2V0IHRvIFZ5IGFzIHNvb24gYXMgcG9zc2libGUsIGFuZCB0aGF0IHdvdWxkIHByb2JhYmx5IGJlIHdpdGhvdXQgZmxhcHMuIAEwAQEBAQ-- X-Mailer: YahooMailWebService/0.8.155.576 References: X-Original-Message-ID: <1377095649.76115.YahooMailNeo@web120101.mail.ne1.yahoo.com> X-Original-Date: Wed, 21 Aug 2013 07:34:09 -0700 (PDT) From: Gary Casey Reply-To: Gary Casey Subject: Re: Flaps on take-off? X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="1072509510-1469197999-1377095649=:76115" --1072509510-1469197999-1377095649=:76115 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable I guess I'll jump in here, but my comments might not be worth 2 cents :-)= =0A=0AThe original question was about whether to use flaps on takeoff, and = like most things, it is a compromise. =A0A logical objective might be to ge= t to Vy as soon as possible, and that would probably be without flaps. =A0B= ut the altitude at that point would probably be less than if you used flaps= . =A0Yes, the workload is less without flaps, and that is a good thing. =A0= The time spent at low altitude would be more and that's a bad thing. =A0And= the on-runway speed would be higher. =A0You pays your money and you takes = your choice.=0A=0AThe second question was about whether prop control is an = effective way to reduce engine-out drag. =A0Bob and Steve are correct, but = the actual ability to control pitch depends on at least 4 things. =A0First,= the airspeed has to be high enough to be able to input enough power to the= prop to spin the engine (almost always the case). =A0Next, the prop pitch = stops have allow enough range to make a difference (almost always the case)= . =A0Then the leakage between the governor and the prop has to be low enoug= h to allow the governor pump, boosted by the engine oil pump, to be able to= move the prop toward the coarse position (in my experience this is also po= ssible). =A0Finally, the governor low-speed stop must be set low enough for= it to take action. =A0In every plane I've tried this on, it works. =A0Gran= ted, with the prop control in the full out position, the engine speed will = not drop to idle, and that's probably limited by the low-rpm stop on the go= vernor and/or the high pitch stop on the prop. =A0It might also be limited by the drop in oi= l pressure as the engine slows down. =A0Regardless, it works and it is sign= ificant. =A0Why going to low rpm hasn't been taught in most curricula, I ha= ve no idea. =A0It should.=0A=0AGary=A0=0A=0A=0A=0A=0AI'm not so sure at idl= e power in flight one can pull the prop back(coarse) =3D=0Athat much.=A0 Ju= st try changing rpm's at low rpm's during run-up .=A0 I have to=3D=0Abe at = around 16-1800 to get the prop to cycle at run-up. Oil pressure play=3D=0A'= s a big part of the governor's ability to move the prop. While at idle pow= =3D=0Aer one may have high enough oil pressure but surly not enough volume = as=A0 18=3D=0A00 + RPM. There will be oil leakage around the front main bea= ring going to =3D=0Athe prop. Off field landings or a return to airport=A0 = is most likely loss of=3D=0Apower of some sort ( low=A0 rpm) wind milling p= rop.=0A=0AMost single engine controllable props are pressure to increase pi= tch, feath=3D=0Aering props are pressure to decrease pitch, unless they are= electric.=0A=0AI may be wrong but that's the way I understand it.=0A=0A=0A= Steve Alderman=A0 N25SA=A0 =A0 360=0A=0A=0A=0AWolfgang,=0AMy MT prop/govern= or does not work as you describe below. Specifically, if t=3D=0Ahe engine i= s turning (with oil pressure), I can control RPM within the mech=3D=0Aanica= l stop limits built into the prop hub, and total power/drag. Idle powe=3D= =0Ar/min RPM/120 KIAS glide gives me 600-650 RPM; Max RPM in that configura= tio=3D=0An gives about 2600 RPM, and the drag increase is significant. At a= bit abov=3D=0Ae idle power, max RPM is limited to 2700 by the governor, al= l the way up to=3D=0Amax power. Min RPM is maintained as power is added=3DE= 2=3D80=3DA6for a while=3DE2=3D=0A=3D80=3DA6but I=3DE2=3D80=3D99ve never gon= e much above idle power. with the prop at m=3D=0Ain RPM=3DE2=3D80=3DA6hard = on the engine=3DE2=3D80=3DA6and it=3DE2=3D80=3D99s not a useful dat=3D=0Aap= oint, but I suspect it will maintain 650 RPM through full power??=0A=0ABob= =0A --1072509510-1469197999-1377095649=:76115 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
I guess I'll j= ump in here, but my comments might not be worth 2 cents :-)

<= /div>
The original question was about whether to use flaps on = takeoff, and like most things, it is a compromise.  A logical objectiv= e might be to get to Vy as soon as possible, and that would probably be wit= hout flaps.  But the altitude at that point would probably be less tha= n if you used flaps.  Yes, the workload is less without flaps, and tha= t is a good thing.  The time spent at low altitude would be more and t= hat's a bad thing.  And the on-runway speed would be higher.  You= pays your money and you takes your choice.
The second question was about whether prop control is an = effective way to reduce engine-out drag.  Bob and Steve are correct, b= ut the actual ability to control pitch depends on at least 4 things.  = First, the airspeed has to be high enough to be able to input enough power = to the prop to spin the engine (almost always the case).  Next, the pr= op pitch stops have allow enough range to make a difference (almost always = the case).  Then the leakage between the governor and the prop has to = be low enough to allow the governor pump, boosted by the engine oil pump, t= o be able to move the prop toward the coarse position (in my experience this is also possible).  Finally, the governor low-speed s= top must be set low enough for it to take action.  In every plane I've= tried this on, it works.  Granted, with the prop control in the full = out position, the engine speed will not drop to idle, and that's probably l= imited by the low-rpm stop on the governor and/or the high pitch stop on th= e prop.  It might also be limited by the drop in oil pressure as the e= ngine slows down.  Regardless, it works and it is significant.  W= hy going to low rpm hasn't been taught in most curricula, I have no idea. &= nbsp;It should.

Gary 




I'm not so sure at idle power in flight one can pull the prop bac= k(coarse) =3D
that much.&nb= sp; Just try changing rpm's at low rpm's during run-up .  I have to=3D=
be at around 16-1800= to get the prop to cycle at run-up. Oil pressure play=3D
's a big part of the governor's abil= ity to move the prop. While at idle pow=3D
er one may have high enough oil pressure but surly no= t enough volume as  18=3D
the prop. Off f= ield landings or a return to airport  is most likely loss of=3D=
power of some sort ( low&nb= sp; rpm) wind milling prop.

Most single engine controllable props are pressure to incr= ease pitch, feath=3D
= ering props are pressure to decrease pitch, unless they are electric.

I m= ay be wrong but that's the way I understand it.

Steve A= lderman  N25SA    360



Wolfgang,=
My MT prop/governor = does not work as you describe below. Specifically, if t=3D
he engine is turning (with oil pressure), I c= an control RPM within the mech=3D
anical stop limits built into the prop hub, and total power/d= rag. Idle powe=3D
r/m= in RPM/120 KIAS glide gives me 600-650 RPM; Max RPM in that configuratio=3D=
n gives about 2600 RPM, and the= drag increase is significant. At a bit abov=3D
e idle power, max RPM is limited to 2700 by the = governor, all the way up to=3D
max power. Min RPM is maintained as power is added=3DE2=3D80=3DA6= for a while=3DE2=3D
= =3D80=3DA6but I=3DE2=3D80=3D99ve never gone much above idle power. with the prop at m=3D
in RPM=3DE2=3D80=3DA6hard on the engine= =3DE2=3D80=3DA6and it=3DE2=3D80=3D99s not a useful dat=3D
apoint, but I suspect it will mainta= in 650 RPM through full power??

Bob
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