Return-Path: Received: from [65.54.169.76] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.2b1) with ESMTP id 3147642 for flyrotary@lancaironline.net; Mon, 05 Apr 2004 20:31:51 -0400 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Mon, 5 Apr 2004 17:31:51 -0700 Received: from 4.174.5.100 by BAY3-DAV46.phx.gbl with DAV; Tue, 06 Apr 2004 00:31:51 +0000 X-Originating-IP: [4.174.5.100] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] : Percent Power, Throttle position, & RD-1C performance Date: Mon, 5 Apr 2004 20:31:48 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01C41B4D.05224420" 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 Message-ID: X-OriginalArrivalTime: 06 Apr 2004 00:31:51.0546 (UTC) FILETIME=[8DF8C5A0:01C41B6E] This is a multi-part message in MIME format. ------=_NextPart_000_000F_01C41B4D.05224420 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Took closer note of throttle position on todays flight. At 2000 ft the = throttle was only about 1/3 open (position of throttle quadrant, but it = closely mirrors butterfly position) at economy cruise setting which was = 6.0 GPH. This is about 42% power, 82 HP according to the EM2 which is = fairly close but not perfectly calibrated yet. The same power setting = with the -B drive would bave been a bit further open. I did a quick check of MAP at 1000 ft at full throttle and found I was = not getting any drop at 150 MPH and had .5" boost at 220 MPH (ram air = recovery I assume). I did not get around to checking it in slow climb = which would more accurately compare to what you would see on a dyno. Finally got some reasonably calm air to do performance comparisons of -C = drive vs -B drive. Without the prop blade cuffs it looks like the break = even point is at 203 MPH. Above that -C burned more fuel than the -B. = After installation of the cuffs, the break even point was off the scale! = i.e., above top speed with -B drive. I had a good data point on the -B = drive while burning 17 GPH (209 mph during SUN 100 race). At the same = speed, the C drive was burning 15.8 gph. This was better than I had = hoped for. Tracy 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. 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'd want to increase that flow area by 30% or so - to about 2" = dia for each rotor.=20 My data may not be representative because of restricted flow to the = TB. The 'airbox' 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. Al ------=_NextPart_000_000F_01C41B4D.05224420 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Took closer note of throttle position = on todays=20 flight. At 2000 ft the throttle was only about 1/3 open (position = of=20 throttle quadrant, but it closely mirrors butterfly position) at economy = cruise=20 setting which was 6.0 GPH. This is about 42% power, 82 HP = according=20 to the EM2 which is fairly close but not perfectly calibrated yet. = The=20 same power setting with the -B drive would bave been a bit further=20 open.

I did a quick check of MAP at 1000 ft = at full=20 throttle and found I was not getting any drop at 150 MPH and had .5" = boost at=20 220 MPH (ram air recovery I assume). I did not get around to = checking it=20 in slow climb which would more accurately compare to what you would see = on a=20 dyno.

Finally got some reasonably calm air to = do=20 performance comparisons of -C drive vs -B drive. Without the prop = blade=20 cuffs it looks like the break even point is at 203 MPH. Above = that -C=20 burned more fuel than the -B. After installation of the cuffs, the = break=20 even point was off the scale! i.e., above top speed with -B drive. = I had a=20 good data point on the -B drive while burning 17 GPH (209 mph = during SUN=20 100 race). At the same speed, the C drive was burning 15.8 = gph. This=20 was better than I had hoped for.

Tracy

Thanks,=20 Tracy. I was = hoping=20 there would be someone out there flying with the same TB=20 diameters.

Like most = things,=20 TB diameter is a tradeoff. My conclusion from the dyno data is = that 44mm=20 per rotor (1 =BE) is a bit small as the MAP is dropping off over 5000 = RPM.=20 But if you want to idle at 1500, and have a decent transition = from there=20 to 3000; 1 =BE is good. For a 2.85 to redrive, I=92d want to = increase that=20 flow area by 30% or so =96 to about 2=94 dia for each rotor. =

My data = may not be=20 representative because of restricted flow to the TB. The = =91airbox=92 size=20 is restricted by the cowl, and may have restricted the flow a bit. = In=20 hindsight, it would have been smart (and easy) to make a run with the = airbox=20 off and see what difference it made.

Al

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