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Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b4) with ESMTP id 120256 for flyrotary@lancaironline.net; Wed, 02 Jun 2004 07:06:55 -0400 Received: from EDWARD (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i52B6LfP000229 for ; Wed, 2 Jun 2004 07:06:22 -0400 (EDT) Message-ID: <002201c44891$a8509e50$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Rev-2.1 part 2 Date: Wed, 2 Jun 2004 07:06:30 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001F_01C44870.21080FD0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_001F_01C44870.21080FD0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageThe velocity aspect seems to carry a lot of weight in rotary = tuning. The reason I say that is my best power (thus far) has been with = the smallest diameter tubes. I have used TB with up to a 75MM opening = and have found them providing less desirable throttle response = characteristics. Not to say that large diameter tubes and throttle = bodies don't have their place. My personal opinion is that until you = are talking 9000+ rpm err on the side of smaller diameter tubes to keep = the velocity up. Tracy has hit 7200 rpm with his small tubes with his = 2.85, so I would think its a bit premature to worry about the 1.75" = being restrictive. Most credible studies/theories on intake tuning put a = lot of emphasis on intake runner velocity, in fact most quote a not to = exceed velocity of Mach 0.6!!! I believe that is the peak air velocity = of the surging intake charge while the average velocity is considerably = lower. =20 Ed Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Tuesday, June 01, 2004 10:23 PM Subject: [FlyRotary] Re: Rev-2.1 part 2 Do you think 48-50mm's would boost power? Mo mix? The allout Racing = Beat wrap around intake uses 48MM Webers or Dellorto carbs. Dave Atkins = is really estute with that rig, so what does he say? TJ=20 One simple theory says that the largest throat possible will decrease = air flow resistance, and let the MAP get closer to the actual ambient = pressure. This ignores the more complicated theory that says that = higher velocity air through a smaller opening will help stuff more air = in the chamber. Everything is a compromise, so your best results will = be somewhere in between tiny, and huge. Ed will calculate this for you, = since he has no flying plane :-) Seriously, my 40 mm (which I didn't chose) has the same ID as the = 1.75" OD tubing that I used for runners. I doubt they're causing me any = problems now, but I do worry that it will be somewhat restrictive when I = get to the -C drive, and 7000+ rpm. If I end up matching Tracy's = static rpm with this setup, it will be interesting to see how I do with = the higher rpm configuration. =20 If you want to know what Dave has to say, give him a call. I've had = my last conversation with him. =20 Cheers, Rusty (low tolerance for BS) ------=_NextPart_000_001F_01C44870.21080FD0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message

The velocity aspect seems to carry a = lot of weight=20 in rotary tuning. The reason I say that is my best power (thus = far) has=20 been with the smallest diameter tubes. I have used TB with up to a 75MM = opening=20 and have found them providing less desirable throttle response=20 characteristics. Not to say that large diameter tubes and throttle = bodies=20 don't have their place. My personal opinion is that = until you=20 are talking 9000+ rpm err on the side of smaller diameter tubes to keep = the=20 velocity up. Tracy has hit 7200 rpm with his small tubes with his = 2.85, so=20 I would think its a bit premature to worry about the 1.75" being = restrictive.=20 Most credible studies/theories on intake tuning put a lot of emphasis on = intake=20 runner velocity, in fact most quote a not to exceed velocity of Mach=20 0.6!!! I believe that is the peak air velocity of the surging = intake=20 charge while the average velocity is considerably lower. =

Ed

Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC

----- Original Message -----
From:=20 Russell=20 Duffy
To: Rotary motors in = aircraft

Sent: Tuesday, June 01, 2004 = 10:23=20 PM

Subject: [FlyRotary] Re: = Rev-2.1 part=20 2

Do = you think=20 48-50mm's would boost power? Mo mix? The allout = Racing Beat=20 wrap around intake uses 48MM Webers or Dellorto carbs. Dave = Atkins=20 is really estute with that rig, so what does he = say?

TJ

One = simple theory=20 says that the largest throat possible will decrease air = flow resistance, and let the MAP get closer to the actual ambient = pressure. This ignores the more complicated theory that says = that higher=20 velocity air through a smaller opening will help stuff more air = in=20 the chamber. Everything is a compromise, so your = best=20 results will be somewhere in between tiny, and huge. Ed will = calculate=20 this for you, since he has no flying plane=20 :-)

Seriously, my 40 mm=20 (which I didn't chose) has the same ID as the 1.75" OD tubing = that I used=20 for runners. I doubt they're causing me any problems now, but I = do worry=20 that it will be somewhat restrictive when I get to the -C drive, and = 7000+=20 rpm. If I end up matching Tracy's static rpm with this=20 setup, it will be interesting to see how I do with the higher=20 = rpm configuration.

If you want = to know what=20 Dave has to say, give him a call. I've had my last = conversation=20 with him.

Cheers,
Rusty (low = tolerance for=20 = BS)

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