X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail11.syd.optusnet.com.au ([211.29.132.192] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTPS id 2352175 for flyrotary@lancaironline.net; Wed, 26 Sep 2007 01:59:48 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.132.192; envelope-from=lendich@optusnet.com.au Received: from george (d58-105-126-227.dsl.nsw.optusnet.com.au [58.105.126.227]) by mail11.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l8Q5wxPQ001969 for ; Wed, 26 Sep 2007 15:59:01 +1000 Message-ID: <000a01c80002$5d518fa0$e37e693a@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Crabs Date: Wed, 26 Sep 2007 15:59:11 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01C80056.2DB6EED0" 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_0007_01C80056.2DB6EED0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ed and Bill, Just some ponderings as I progress along my way of understanding = different carb developments. I notice with a slide carb ( round on round opening) you get more = of a straight line function of air to fuel ratio as it progressively = opens. With a flat slide on round opening you get 'diminishing returns' ( = my term) as you get past half way. I notice that some carbs have eggs shaped openings, I guess that's = to even out the percentage of fuel/air mix to percentage of opening and = to compensate for the enrichening at higher RPM i.e. more air to fuel at = higher rpm at the fatter end (top). I was wondering what was wrong with a square carb - not completely = square mind you, but with some roundness to corners say 1/2 diameter. Wouldn't this provide for a more linier opening to fuel/ air ratio = mix OR does this pose other problems such as air flow and drag/ = turbulence?=20 George (down under) Typing your subject line a bit fast there George? Actually Ford tried a completely square opening just prior to going to = FI. The attempt was to make the carb throat into a supersonic nozzle. It = had a square, or rather a rectangular opening with a specially shaped = ramp on one side that moved. It was electronically controlled. That was = suposed to be it's weak point the electronics would faill and the nozzle = wouldn't work. Then it was just a crappy wierd looking carb! Hard to = beat the two circles system. Many have tried and many have failed. If = your making a new carb, just go round and save yourself some trouble. = You need the linear change in opening to keep everything working = properly. You can do it other ways, (the Predator carb uses two barn = door type flaps that open into the throat, leaving a square opening), = but EXPECT to have a BUNCH of development time in it to get it to work. Bill Jepson Bill, Thanks Bud - I'm hearing you. I won't attempt the degree of complexity = you are mentioning - but it's all very interesting! I thought about an electrically controlled needle that moved up and = down that was governed by an O2 sensor reading, but it would require = very fine adjustments, probably a small servo motor - beyond my = capacity. Until I win Lotto that is! Marvelous how the mind probes the different concepts. As soon as I = sent the last e-mail I realised a completely square carb would have too = much opening at the lower end - hence the egg shape that has been used. I'm now thing half round at the bottom ( to centre) and then square = sides at the top half. It's worth looking at - but blending the shapes i.e. carb to round = inlet tube might be a neat trick. George ( down under) -------------------------------------------------------------------------= ----- See what's new at AOL.com and Make AOL Your Homepage. -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.488 / Virus Database: 269.13.30/1029 - Release Date: = 24/09/2007 7:09 PM ------=_NextPart_000_0007_01C80056.2DB6EED0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Ed and Bill,
Just some ponderings as I progress = along my way=20 of understanding different carb developments.
 
I notice with a slide carb ( round = on round=20 opening) you get  more of a straight line function of air to = fuel ratio=20 as it progressively opens.
With a flat slide on round opening = you get=20 'diminishing returns' ( my term) as you get past half = way.
 
I notice that some carbs have eggs = shaped=20 openings, I guess that's to even out the percentage of fuel/air mix = to=20 percentage of opening and to compensate for the enrichening at = higher RPM=20 i.e. more air to fuel at higher rpm at the fatter end = (top).
 
I was wondering what was wrong with = a square=20 carb - not completely square mind you, but with some roundness = to=20 corners say 1/2 diameter.
Wouldn't this provide for a more = linier opening=20 to fuel/ air ratio mix OR does this pose other problems such as air = flow and=20 drag/ turbulence? 
 
George (down=20 under)
Typing your subject line a bit fast there George?
Actually Ford tried a completely square opening just prior to = going to=20 FI. The attempt was to make the carb throat into a supersonic nozzle. = It had a=20 square, or rather a rectangular opening with a specially shaped ramp = on one=20 side that moved. It was electronically controlled. That was suposed to = be it's=20 weak point the electronics would faill and the nozzle wouldn't work. = Then it=20 was just a crappy wierd looking carb! Hard to beat the two circles = system.=20 Many have tried and many have failed. If your making a new carb, just = go round=20 and save yourself some trouble. You need the linear change in opening = to keep=20 everything working properly. You can do it other ways, (the Predator = carb uses=20 two barn door type flaps that open into the throat, leaving a square = opening),=20 but EXPECT to have a BUNCH of development time in it to get it to = work.
Bill Jepson

 
Bill,
Thanks Bud - I'm hearing you. I won't attempt the degree of = complexity=20 you are mentioning - but it's all very interesting!
 
I thought about an electrically controlled needle that moved up = and down=20 that was governed by an O2 sensor reading, but it would require very = fine=20 adjustments, probably a small servo motor - beyond my capacity. = Until I=20 win Lotto that is!
 
Marvelous how the mind probes the different concepts. As soon as = I sent=20 the last e-mail I realised a completely square carb would have too = much=20 opening at the lower end - hence the egg shape that has been = used.
 
I'm now thing half round at the bottom ( to centre) and then = square sides=20 at the top half.
It's worth looking at - but blending the shapes i.e. carb to = round inlet=20 tube might be a neat trick.
George ( down under)

See what's new at AOL.com=20 and Make AOL Your Homepage.

No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.488 / Virus Database: 269.13.30/1029 - = Release Date:=20 24/09/2007 7:09 PM
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