Return-Path: Received: from fed1rmmtao10.cox.net ([68.230.241.29] verified) by logan.com (CommuniGate Pro SMTP 4.2b1) with ESMTP id 3145369 for flyrotary@lancaironline.net; Sun, 04 Apr 2004 12:26:12 -0400 Received: from BigAl ([68.107.116.221]) by fed1rmmtao10.cox.net (InterMail vM.6.01.03.01 201-2131-111-101-20040311) with ESMTP id <20040404162612.DSYD25767.fed1rmmtao10.cox.net@BigAl> for ; Sun, 4 Apr 2004 12:26:12 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: : Percent Power, Throttle position Date: Sun, 4 Apr 2004 09:26:18 -0700 Message-ID: <000f01c41a61$8efe5900$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0010_01C41A26.E29F8100" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 In-Reply-To: Importance: Normal This is a multi-part message in MIME format. ------=_NextPart_000_0010_01C41A26.E29F8100 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Subject: [FlyRotary] Re: Percent Power, Throttle position =20 You gave a pretty good list of parameters so I think I can make a pretty good guess, especially since you used the same TB throat size as I did. (side note: I think the "bigger is better" approach is the wrong way = to go. There is another rotary advocate recommending a 4 inch or larger = TB. ) =20 I'm going from memory here but it seems that at cruise altitude I'm = using about 2/3 travel on throttle quadrant (econo cruise). Down at sea level this same setting is a lot more power. As you pointed out, there is no single answer but if the throttle were 40 - 50% open, you could fly most anywhere safely and comfortably. =20 =20 Thanks, Tracy. I was hoping there would be someone out there flying with = the same TB diameters. =20 Like most things, TB diameter is a tradeoff. My conclusion from the = dyno data is that 44mm per rotor (1 =BE) is a bit small as the MAP is = dropping off over 5000 RPM. But if you want to idle at 1500, and have a decent transition from there to 3000; 1 =BE is good. For a 2.85 to redrive, = I=92d want to increase that flow area by 30% or so =96 to about 2=94 dia for each = rotor.=20 =20 My data may not be representative because of restricted flow to the TB. = The =91airbox=92 size is restricted by the cowl, and may have restricted the = flow a bit. In hindsight, it would have been smart (and easy) to make a run = with the airbox off and see what difference it made. =20 Al =20 =20 ------=_NextPart_000_0010_01C41A26.E29F8100 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Subject: [FlyRotary] Re: Percent Power, Throttle position

You gave a pretty good = list of parameters so I think I can make a pretty good guess, especially since = you used the same TB throat size as I did. (side note: I think = the "bigger is better" approach is the wrong way to go. = There is another rotary advocate recommending a 4 inch or larger = TB. )

I'm going from memory = here but it seems that at cruise altitude I'm using about 2/3 travel on throttle = quadrant (econo cruise). Down at sea level this same setting is a = lot more power. As you pointed out, there is no single answer = but if the throttle were 40 - 50% open, you could fly most anywhere safely and comfortably.

Thanks, Tracy. I was hoping = there would be someone out there flying with the same TB = diameters.

Like most things, TB diameter is = a tradeoff. =A0My conclusion from the dyno data is that 44mm per rotor (1 = =BE) is a bit small as the MAP is dropping off over 5000 RPM. =A0But if you want = to idle at 1500, and have a decent transition from there to 3000; 1 =BE is good. = =A0For a 2.85 to redrive, I’d want to increase that flow area by 30% or so = – to about 2” dia for each rotor.

My data may not be representative because of restricted flow to the TB.=A0 The ‘airbox’ size = is restricted by the cowl, and may have restricted the flow a bit. =A0In = hindsight, it would have been smart (and easy) to make a run with the airbox off = and see what difference it made.

Al

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