Return-Path: Received: from qmail.accesscomm.ca ([204.83.142.82] verified) by logan.com (CommuniGate Pro SMTP 4.1.5) with SMTP id 2638165 for flyrotary@lancaironline.net; Wed, 15 Oct 2003 15:23:30 -0400 Received: (qmail 8880 invoked from network); 15 Oct 2003 19:23:29 -0000 Received: from cust140-67.weyburn-leg.accesscomm.ca (HELO Jarrett) (216.174.140.67) by qmail.accesscomm.ca with SMTP; 15 Oct 2003 19:23:29 -0000 Message-ID: <001a01c39351$cf0ebef0$8200a8c0@Jarrett> From: "JJ JOHNSON" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: rooster-tail drag Date: Wed, 15 Oct 2003 13:23:26 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0017_01C3931F.8407D180" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_0017_01C3931F.8407D180 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I have never seen a NACA scoop used to vent air FROM the aircraft BACK = into airstreams. I have reviewed all the NACA papers on scoops and have never seen this = effect described. Please point us to any reference on the subject. Respectfully, Eric Eric, I have to admit I've never seen this analyzed on paper however = I've seen it in practice and the builder swore by it. He had extended = the edge of the opening back a bit 1/4-3/8" as well as rounded the ramp = into the opening as to smooth the transition. I just took his word for = it that it could be used either way. You've got me thinking now but I = see why it wouldn't work? I guess maybe the converging ramp sides might = pre-maturely force the air out into the slip-stream but other than = that.. I guess worst case scenario is to eliminate the converging = ramps. One thing that I would steer clear of [or at least I will on my = a/c] is the shark gill type exits. I have read somewhere that they are = one of the worst types of exits for air.. now where I read that I don't = know.. but I'm going to try and find out. Maybe there are some other = aerodynamics types out there that can help me/us w/ this? Please don't take what I say as the gospel truth.. I'm no expert, but I = try to learn/know all I can about the subject. Jarrett ------=_NextPart_000_0017_01C3931F.8407D180 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

I have never seen a NACA scoop used = to vent air=20 FROM the aircraft BACK into airstreams.

I have reviewed all the NACA papers = on scoops=20 and have never seen this effect described. Please point us to any=20 reference on the subject.

Respectfully,

Eric

Eric, I have to admit I've never seen = this analyzed=20 on paper however I've seen it in practice and the builder swore by it. = He had=20 extended the edge of the opening back a bit 1/4-3/8" as well as rounded = the ramp=20 into the opening as to smooth the transition. I just took his word for = it that=20 it could be used either way. You've got me thinking now but I see why it = wouldn't work? I guess maybe the converging ramp sides might = pre-maturely force=20 the air out into the slip-stream but other than that.. I guess = worst case=20 scenario is to eliminate the converging ramps. One thing that I would = steer=20 clear of [or at least I will on my a/c] is the shark gill type exits. I = have=20 read somewhere that they are one of the worst types of exits for air.. = now where=20 I read that I don't know.. but I'm going to try and find out. Maybe = there are=20 some other aerodynamics types out there that can help me/us w/=20 this?

Please don't take what I say as the = gospel=20 truth.. I'm no expert, but I try to learn/know all I can about the = subject.

Jarrett

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