Return-Path: <13brv3@bellsouth.net> Received: from imf22aec.mail.bellsouth.net ([205.152.59.70] verified) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2579085 for flyrotary@lancaironline.net; Sun, 14 Sep 2003 12:18:27 -0400 Received: from rad ([68.212.12.251]) by imf22aec.mail.bellsouth.net (InterMail vM.5.01.05.27 201-253-122-126-127-20021220) with ESMTP id <20030914161827.LFYX12046.imf22aec.mail.bellsouth.net@rad> for ; Sun, 14 Sep 2003 12:18:27 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Good news, Bad news Date: Sun, 14 Sep 2003 11:18:27 -0500 Message-ID: <002c01c37adb$d4a908e0$0201a8c0@rad> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002D_01C37AB1.EBD300E0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_002D_01C37AB1.EBD300E0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable With stock ports and pulling off power to limit boost. I think your only problem is the waste gate size. Or flow, but that is the Idea.=20 I certainly agree about the wastegate problem, and I'm skeptical that porting it will help enough. =20 The cowl shape, or lack of a cowl is not going to make much difference in the climb at 100 KTS.=20 Thanks for the confirmation of this, and to others who made it as well. = It would seem that the cowl just can't be the whole problem. Taking out pitch, and then limiting RPM, limits excess HP required for climb. More typical would be enough pitch to stall the prop on a hot day and have to back off the = power slightly to unstall it until some ground speed has built up.=20 I've been adjusting the throttle for 30 inches of MAP, rather than for a particular RPM, so the RPM has in fact gone up with reducing pitch. = Another reason to suspect that I'm not putting out the proper amount of power is = the pitch. Warp estimated that I would need an 18 degree pitch setting, = which is what I started out with. Static RPM wasn't constant at 18 or even as = low as 15 degrees, and I found out that the prop was indeed stalled to some extent at those pitch settings. My first climb RPM's were very low, = 4700 with full throttle, 15 degrees of pitch, and 36 inches MAP. Reducing = the pitch to 12 degrees, gave me 6300 RPM at full throttle, 36 inches MAP. = This is way below the pitch that Warp estimated, and I'm betting that they wouldn't be off that much. It would seem to indicate that I'm not = making the power I should be. Once you can lay into it at WOT all the way up to 6,500, you should see at least 160HP performance = or more. In my current configuration, I have to limit the throttle opening to = about half throttle, to maintain 30 inches MAP. All along, I've been assuming that this give me the same power as a NA engine using full throttle. I = know there are some losses with the higher temp of the intake, but I wouldn't expect them to add up to that much.=20 Here's my question- Is my above assumption correct? I've tried to = follow some intake flow discussions in the past on the RX-7 forum, where they = were stating that pressure isn't everything. The idea (as I think I = understood it) was that having good pressure registering on a gauge didn't = guarantee anything, since the gauge isn't fast enough to show you what's really happening. They said that if the pipe was restrictive, or there was = some other obstacle to flow (throttle butterflies half closed), you wouldn't = get the power you should, because the pressure would drop instantaneously = when the ports opened. When that happens, I guess the engine doesn't get the charge that it would appear to be getting from the gauge. Is this more = or less what you're getting at when you say I need to be a WOT to get good power? =20 Thanks for all the thoughts. Rusty (still baffled)=20 ------=_NextPart_000_002D_01C37AB1.EBD300E0 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Message

With stock ports and
pulling off power to limit = boost. I=20 think your only problem is the waste gate
size. Or flow, but that is = the=20 Idea.

I certainly agree about the = wastegate problem,=20 and I'm skeptical that porting it will help = enough.  

The cowl shape, or lack of a cowl is not
going to = make much=20 difference in the climb at 100 KTS.

Thanks for the confirmation of = this, and to=20 others who made it as well.  It would seem that the cowl just can't = be the=20 whole problem.

Taking out pitch, and then
limiting RPM, limits = excess HP=20 required for climb. More typical would be
enough pitch to stall the = prop on a=20 hot day and have to back off the power slightly
to unstall it until = some=20 ground speed has built up.

I've been adjusting the throttle = for 30=20 inches of MAP, rather than for a particular RPM, so the RPM has in fact = gone up=20 with reducing pitch.  Another reason to suspect that I'm not = putting=20 out the proper amount of power is the pitch.  Warp estimated that I = would=20 need an 18 degree pitch setting, which is what I started out with.  = Static=20 RPM wasn't constant at 18 or even as low as 15 degrees, and I found out = that the=20 prop was indeed stalled to some extent at those pitch settings.  My = first=20 climb RPM's were very low, 4700 with full throttle, 15 degrees of pitch, = and 36=20 inches MAP.  Reducing the pitch to 12 degrees, gave me 6300 RPM at = full=20 throttle, 36 inches MAP.  This is way below the pitch that Warp = estimated,=20 and I'm betting that they wouldn't be off that much.  It would seem = to=20 indicate that I'm not making the power I should be.

Once you can lay into it at
WOT all the way up to = 6,500, you=20 should see at least 160HP performance or more.

In my = current=20 configuration, I have to limit the throttle opening to about half = throttle, to=20 maintain 30 inches MAP.  All along, I've been assuming that this = give me=20 the same power as a NA engine using full throttle.  I know there = are some=20 losses with the higher temp of the intake, but I wouldn't expect them to = add up=20 to that much.

Here's my question- Is my = above=20 assumption correct?  I've tried to follow some intake flow = discussions in=20 the past on the RX-7 forum, where they were stating that pressure isn't=20 everything.  The idea (as I think I understood it) was that=20 having good pressure registering on a gauge didn't guarantee = anything,=20 since the gauge isn't fast enough to show you what's really = happening. =20 They said that if the pipe was restrictive, or there was some other = obstacle to flow (throttle butterflies half closed), you wouldn't get = the power=20 you should, because the pressure would drop instantaneously when the = ports=20 opened.  When that happens, I guess the engine doesn't get the = charge that=20 it would appear to be getting from the gauge.  Is this more or less = what=20 you're getting at when you say I need to be a WOT to get good=20 power?  

Thanks for all the=20 thoughts.
 Rusty (still=20 baffled) 



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