X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail02.syd.optusnet.com.au ([211.29.132.183] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTPS id 2573108 for flyrotary@lancaironline.net; Sun, 09 Dec 2007 04:32:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=211.29.132.183; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-119-124.dsl.nsw.optusnet.com.au [211.31.119.124]) by mail02.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id lB99VBTu028052 for ; Sun, 9 Dec 2007 20:31:13 +1100 Message-ID: <000a01c83a46$3fbafd40$7c771fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" Subject: PP Timing Date: Sun, 9 Dec 2007 19:31:14 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01C83A9A.100AFFB0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0005_01C83A9A.100AFFB0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lynn, I address this to you or anyone that wants to comment. I'm just re-evaluating, the PP position and I'm looking at the latest = possible closing position for the PP (100 degrees ATDC). In the standard opening ( 12A housing set-up with my degree wheel) I = have opening at 32 degree ATDC, closing at 310 degrees with exhaust = closing at 55 degrees ATDC. This gives a moderate overlap of 23 degrees = and an Inlet opening period of 278 degrees (quite large). With the PP (approx 2") we have an early opening of 20 degrees BBDC and = 65 degrees ABDC, open for only 85 degrees- but an over lap of 165 = degrees. This gives an additional overlap of 142 degrees and reduced inlet = opening time of 193 degrees - it's a wonder the rotary runs at all with = reduced opening time and additional over lap. One compensation however = is that the inlet is direct and bigger. In considering a later PP, I figure the inlet opening could be 40 degree = ABDC (only restriction is the top housing bolt hole) and closing at 100 = degree ABDC. This would then would reduce the overlap by 55 degrees, so the overlap = would be ( 165 - 55) 110 degrees, still high but not quite as high, thus = reducing exhaust contamination of the inlet ( at low RPM) and inlet = going into the exhaust (at high RPM). The inlet timing would be the same ( 85 degrees) - but later, but not so = late as to get into the compression stage, which might cause further = issues. I remember discussing this with someone ( it might have been Lynn) but I = can't remember what the negatives are with such a late PP. Can someone put me straight on this again! I hope I got those degrees right! George ( down under) ------=_NextPart_000_0005_01C83A9A.100AFFB0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Lynn,

I address this to you or anyone that = wants to=20 comment.

I'm just re-evaluating, the PP position = and I'm=20 looking at the latest possible closing position for the PP (100 degrees=20 ATDC).

In the standard opening ( 12A housing = set-up with=20 my degree wheel) I have opening at 32 degree ATDC, closing at 310 = degrees with=20 exhaust closing at 55 degrees ATDC. This gives a moderate overlap of 23 = degrees=20 and an Inlet opening period of 278 degrees (quite large).

With the PP (approx 2") we have an = early opening of=20 20 degrees BBDC and 65 degrees ABDC, open for only 85 degrees- but an = over lap=20 of 165 degrees.

This gives an additional overlap of 142 = degrees and=20 reduced inlet opening time of 193 degrees - it's a wonder the rotary = runs at all=20 with reduced opening time and additional over lap. One compensation = however is=20 that the inlet is direct and bigger.

In considering a later PP, I figure the = inlet=20 opening could be 40 degree ABDC (only restriction is the top = housing bolt=20 hole) and closing at 100 degree = ABDC.

This would then would reduce the = overlap by 55=20 degrees, so the overlap would be ( 165 - 55) 110 degrees, still high but = not=20 quite as high, thus reducing exhaust contamination of the inlet ( at low = RPM)=20 and inlet going into the exhaust (at high RPM).

The inlet timing would be the same ( 85 = degrees) - but later, but not so late as to get into the = compression stage,=20 which might cause further issues.

I remember discussing this with someone = ( it might=20 have been Lynn) but I can't remember what the negatives are with such a = late=20 PP.

Can someone put me straight on this=20 again!

I hope I got those degrees = right!

George ( down under)

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