X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 2 [X] Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 14 Apr 2007 13:20:02 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m28.mx.aol.com ([64.12.137.9] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 1985152 for lml@lancaironline.net; Sat, 14 Apr 2007 12:03:29 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.9; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m28.mx.aol.com (mail_out_v38_r8.1.) id q.cf5.a454aea (32913) for ; Sat, 14 Apr 2007 12:02:28 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Sat, 14 Apr 2007 12:02:28 EDT Subject: Re: [LML] bicambered technology X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1176566548" X-Mailer: 9.0 Security Edition for Windows sub 5365 X-Spam-Flag: NO -------------------------------1176566548 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 4/14/2007 10:35:15 A.M. Central Daylight Time, kneadedpleasures@sbcglobal.net writes: I extend an invitation for the aeronautical/ fluids/ physical/ mechanical/ etc. types among us to opine on why the once promising and highly-touted technology of bicambered airfoils has not resulted in tangible products that we can use in our avocation. In other words, what's wrong with it? Greg It's patented. However, one could say that the wing with reflexed flaps used in the Lancair 300 series is a form of semi-demi bi-cambered wing. It does indeed reduce drag in the reflexed regime (upper air reattached at the flap), pitching moment and lift changes notwithstanding. I once had a "dog-bone" prop made for an experimentally registered heavy ultra-light that did use the bi-cambered construction concept for the blade surfaces (hence the dog bone looking cross section). I used it once - never again. It delivered some thrust at max RPM and less noise. It delivered no thrust and little noise at less than max RPM (except for my screams on the short test flight). I am sorry that this is not the engineer's reply you are seeking. Perhaps the wind tunnel doesn't work the same as flights in earth's atmosphere. Does rain pool in the concave upper portion whilst parked? Does that later freeze on a cold day and, uh, break things? Does it accumulate ice on the front and back parts of the airfoil if flown in icing conditions? Grayhawk ************************************** See what's free at http://www.aol.com. -------------------------------1176566548 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 4/14/2007 10:35:15 A.M. Central Daylight Time,=20 kneadedpleasures@sbcglobal.net writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I extend=20 an invitation for the aeronautical/ fluids/ physical/ mechanical/ etc. typ= es=20 among us to opine on why the once promising and highly-touted technology o= f=20 bicambered airfoils has not resulted in tangible products that=20 we can use in our avocation. In other words, what's wrong with=20 it?

Greg

It's patented.

However, one could say that the wing with reflexed flaps used= in=20 the Lancair 300 series is a form of semi-demi bi-cambered wing. =20 It does indeed reduce drag in the reflexed regime (upper air reattached= at=20 the flap), pitching moment and lift changes notwithstanding.

I once had a "dog-bone" prop made for an experimentally registered heav= y=20 ultra-light that did use the bi-cambered construction concept for the b= lade=20 surfaces (hence the dog bone looking cross section). I used it on= ce -=20 never again. It delivered some thrust at max RPM and less noise. =20= It=20 delivered no thrust and little noise at less than max RPM (except=20 for my screams on the short test flight).

I am sorry that this is not the engineer's reply you are=20 seeking. Perhaps the wind tunnel doesn't work the same as flights=20 in earth's atmosphere.

Does rain pool in the concave upper portion whilst parked? D= oes=20 that later freeze on a cold day and, uh, break things? Does it accumul= ate=20 ice on the front and back parts of the airfoil if flown in icing conditions?= =20

Grayhawk

See what's fre= e at AOL.com.=20=

-------------------------------1176566548--