X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 30 [X] Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 30 Apr 2007 22:17:44 -0400 Message-ID: X-Original-Return-Path: Received: from fed1rmmtao101.cox.net ([68.230.241.45] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2018430 for lml@lancaironline.net; Mon, 30 Apr 2007 20:23:44 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.45; envelope-from=bstrat1@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao101.cox.net (InterMail vM.7.05.02.00 201-2174-114-20060621) with ESMTP id <20070501002247.WEDY1235.fed1rmmtao101.cox.net@fed1rmimpo02.cox.net> for ; Mon, 30 Apr 2007 20:22:47 -0400 Received: from nonejvpl2ckt1n ([68.6.76.125]) by fed1rmimpo02.cox.net with bizsmtp id tcNl1W00K2iC6CL0000000; Mon, 30 Apr 2007 20:22:47 -0400 X-Original-Message-ID: <001501c78b86$d9b14360$0300a8c0@nonejvpl2ckt1n> From: "Bruce Stratton" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: Augmenter, ventral fin X-Original-Date: Mon, 30 Apr 2007 17:22:49 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01C78B4C.2D231E00" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 This is a multi-part message in MIME format. ------=_NextPart_000_0012_01C78B4C.2D231E00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable The T-34 has augmenter tubes. ----- Original Message -----=20 From: marv@lancair.net=20 To: lml@lancaironline.net=20 Sent: Monday, April 30, 2007 11:40 AM Subject: [LML] Re: Augmenter, ventral fin Posted for "Paul Lipps" : An augmenter is a device in which the exhaust energy is used to = accelerate=20 the engine's cooling air to bring it near free-stream velocity to = minimize=20 cooling drag. it also acts to improve airflow through the engine in = static=20 condition, as when holding or taxi-ing, to keeep the engine from = overheating.=20 Several multi-engine aircraft, such as the Aero-Commander, made use of = this.=20 In its simplest form it is a tube with a length-diameter ratio of at = least=20 five in which the cooling air and exhaust enters on one end and the = combined=20 flow exits the other. My Lancair uses a little more complicated = version, with=20 the exhaust-cooling mixing taking place immediately (<2") below the = cylinder,=20 then both conducted out through a duct with a variable aperture (cowl = flap) at=20 the exit end. Augmenters, as all open-ended tubes, such as an exhaust = pipe,=20 will pick out harmonics from the exhaust stream, which is rich in = them, and=20 resonate to make lots of noise at those harmonics of its length. This = noise=20 may be mitigated in both augmenter tubes and exhaust tubes by "baloney = slicing" the outlet end so as to spread the resonance over a wider = spectrum=20 and so reduce the peak amplitude. I installed a ventral fin on my Lancair during construction, but it's = a=20 much-abreviated form of the one that extended forward almost to the = wing that=20 you saw in the early days. It made a handy fixed position to attach = the rear=20 nav light, and also, by making the bottom of the rudder straight = rather than=20 curved, and having the ventral fin closely-spaced to it, enhances the = control=20 power of the rudder. =20 -------------------------------------------------------------------------= ----- -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html ------=_NextPart_000_0012_01C78B4C.2D231E00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
The T-34 has augmenter = tubes.
----- Original Message -----
From:=20 marv@lancair.net=20
Sent: Monday, April 30, 2007 = 11:40=20 AM
Subject: [LML] Re: Augmenter, = ventral=20 fin


Posted for "Paul = Lipps"=20 <elippse@sbcglobal.net>:
<= BR>An=20 augmenter is a device in which the exhaust energy is used to = accelerate=20
the engine's cooling air to bring it near free-stream velocity to = minimize=20
cooling drag. it also acts to improve airflow through the engine = in static=20
condition, as when holding or taxi-ing, to keeep the engine from=20 overheating.
Several multi-engine aircraft, such as the = Aero-Commander,=20 made use of this.
In its simplest form it is a tube with a = length-diameter=20 ratio of at least
five in which the cooling air and exhaust enters = on one=20 end and the combined
flow exits the other. My Lancair uses a = little more=20 complicated version, with
the exhaust-cooling mixing taking place=20 immediately (<2") below the cylinder,
then both conducted out = through a=20 duct with a variable aperture (cowl flap) at
the exit end. = Augmenters, as=20 all open-ended tubes, such as an exhaust pipe,
will pick out = harmonics=20 from the exhaust stream, which is rich in them, and
resonate to = make lots=20 of noise at those harmonics of its length. This noise
may be = mitigated in=20 both augmenter tubes and exhaust tubes by "baloney
slicing" the = outlet end=20 so as to spread the resonance over a wider spectrum
and so reduce = the peak=20 amplitude.
I installed a ventral fin on my Lancair during = construction, but=20 it's a
much-abreviated form of the one that extended forward = almost to the=20 wing that
you saw in the early days. It made a handy fixed = position to=20 attach the rear
nav light, and also, by making the bottom of the = rudder=20 straight rather than
curved, and having the ventral fin = closely-spaced to=20 it, enhances the control
power of the rudder.
 

--
For archives and unsub=20 = http://mail.lancaironline.net:81/lists/lml/List.html
------=_NextPart_000_0012_01C78B4C.2D231E00--