X-Virus-Scanned: clean according to Sophos on Logan.com X-PolluStop-Diagnostic: (direct reply)\eX-PolluStop-Score: 0.00\eX-PolluStop: Scanned with Niversoft PolluStop 2.1 RC1, http://www.niversoft.com/pollustop Return-Path: Received: from fed1rmmtao10.cox.net ([68.230.241.29] verified) by logan.com (CommuniGate Pro SMTP 4.3c4) with ESMTP id 866945 for flyrotary@lancaironline.net; Tue, 12 Apr 2005 19:19:44 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.29; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao10.cox.net (InterMail vM.6.01.04.00 201-2131-118-20041027) with ESMTP id <20050412231855.MPYG2123.fed1rmmtao10.cox.net@BigAl> for ; Tue, 12 Apr 2005 19:18:55 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Ram and Alt air Date: Tue, 12 Apr 2005 16:19:08 -0700 Message-ID: <000501c53fb6$073f64c0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Here is pic of the plenum (at this point a piece of 1/4 inch ply. The=20 ram air scoop will be 4 inches wide and two inches high. =20 Jerry: Is the 2" x 4" the opening size? I think that is more than double the = area that would give the amount of ram air needed for a 2-rotor at, say, 120 = kts. So it will be spilling air and likely cause some amount of unwanted = drag. Ideally, a ram induction scoop is close to the area needed for near top speed; and have radius on the entrance lip (about that of your index = finger) to minimize entrance loss when you are at low speed. FWIW, I have no idea it any of this matters for what you're doing. Al