X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail06.syd.optusnet.com.au ([211.29.132.187] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTPS id 2270207 for flyrotary@lancaironline.net; Sat, 18 Aug 2007 03:12:57 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.132.187; envelope-from=lendich@optusnet.com.au Received: from george (d58-108-92-62.dsl.nsw.optusnet.com.au [58.108.92.62]) by mail06.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l7I7C6Aa018977 for ; Sat, 18 Aug 2007 17:12:08 +1000 Message-ID: <002901c7e167$17976f70$3e5c6c3a@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Air/fuel flow Date: Sat, 18 Aug 2007 17:12:07 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0026_01C7E1BA.E7E045F0" 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_0026_01C7E1BA.E7E045F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lynn, The question was on inlet velocity for a Mazda rotary at 7,500 rpm - if = you happened to have some info on that. Everyday cars have 450' per sec and race cars 125' per second,( = suggested on a carb site) Ed's calculations used 176' per second which = indicated a bigger inlet diameter. I was thinking about 300 to 350' per = second would more like it, but I have no real hard data! I indicated the Revmaster didn't have a venturi ( as stated by them), so = I was questioning the strength of the vacuum signal and the impact on = fuel flow. They said that the flat side on the needle created a low = pressure area which sucked-up the fuel and then was sucked in by the = vacuum of the engine etc etc. George ( down under) ----- Original Message -----=20 From: Lehanover@aol.com=20 To: Rotary motors in aircraft=20 Sent: Saturday, August 18, 2007 2:28 PM Subject: [FlyRotary] Re: Air/fuel flow In a message dated 8/17/2007 9:31:07 P.M. Eastern Daylight Time, = lendich@optusnet.com.au writes: I have asked Revmaster for air flow and velocity figures, but these = may be derived from piston engine type figures. If you or Lynn could comment on this it would be greatly = appreciated.=20 Also my research indicates that flow air/ fuel mix richens at higher = RPM and altitude. I can't remember why at higher RPM - mind block, = however for altitude it is because fuel flow is driven by air flow and = even though the density of the air is lower ( at altitude) the flow = remains the same - therefore richer mixture. Revmaster says their needle = design is self leaning ( to a degree) because of design. I assume = because the air density directly affects the suction to the rear side of = the flat ground needle, ( this provides the low pressure area rather = than the venturi) therefore with reduced density you have reduced = suction and reduced fuel and leaner mixture. However I will clarify that = when next we talk. I find this all very interesting! George ( down under) I have missed the question.=20 Carbs get leaner near the top of their RPM ranges and use a number of = tricks to maintain a reasonable F/A at high RPM. Even Webers with a huge = number of emulsion tubes and jets for any imagined situation. If you = actually remove the venturi (called the choke) from a carburetor it no = longer will develop any differential pressure, and no fuel will flow = through it.=20 None is way too lean.=20 More like the Bendix dribble fuel injection that is based on a = positive displacement pump geared to the engine. It just pees fuel all = of the time. Crude but effective.=20 In many cases of a slide and needle type of carb, the edges of the = slide hole and the flat shelf the slide seals against, is more than = enough turbulence to form the choke. Like Posa, Stromberg, SU and any = motorcycle carb. They all have chokes even though it is not obvious.=20 A 12A dyno sheet shows 139.6 foot pounds of torque at 6,500 RPM. and = 173.3 HP. This is an engine designed for 9,600 RPM shifting. This has a = Weber carb has two 36MM chokes. Two 40MM chokes would be real nice. = Longer runners would be better, so cruise RPM is also the peak torque or = a bit above peak.=20 Lynn E. Hanover=20 -------------------------------------------------------------------------= ----- Get a sneak peek of the all-new AOL.com. -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.484 / Virus Database: 269.12.0/959 - Release Date: = 17/08/2007 5:43 PM ------=_NextPart_000_0026_01C7E1BA.E7E045F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Lynn,
The question was on inlet velocity for a Mazda rotary at 7,500 rpm = - if you=20 happened to have some info on that.
 
Everyday cars have 450' per sec and race cars 125' per second,( = suggested=20 on a carb site) Ed's calculations used 176' per second which = indicated=20 a bigger inlet diameter. I was thinking about 300 to 350' per second = would more=20 like it, but I have no real hard data!
 
I indicated the Revmaster didn't have a venturi ( as stated by = them), so I=20 was questioning the strength of the vacuum signal and the impact on fuel = flow.=20 They said that the flat side on the needle created a low pressure  = area=20 which sucked-up the fuel and then was sucked in by the vacuum of the = engine etc=20 etc.
George ( down under)
----- Original Message -----
From:=20 Lehanover@aol.com
Sent: Saturday, August 18, 2007 = 2:28=20 PM
Subject: [FlyRotary] Re: = Air/fuel=20 flow

In a message dated 8/17/2007 9:31:07 P.M. Eastern Daylight Time, = lendich@optusnet.com.au=20 writes:
I have asked Revmaster for air flow = and=20 velocity figures, but these may be derived from piston engine type=20 figures.
 
If you or Lynn could comment on = this it would=20 be greatly appreciated.
 
Also my research indicates that = flow air/=20 fuel mix richens at higher RPM and altitude. I can't remember = why at=20 higher RPM - mind block, however for altitude it is because = fuel flow=20 is driven by air flow and even though the density of the air is = lower (=20 at altitude) the flow remains the same - therefore richer mixture. = Revmaster=20 says their needle design is self leaning ( to a degree) because of = design.=20 I assume because the air density directly affects the suction = to the=20 rear side of the flat ground needle, ( this provides the low = pressure area=20 rather than the venturi) therefore with reduced density you = have=20 reduced suction and reduced fuel and leaner mixture. However I = will=20 clarify that when next we talk.
I find this all very = interesting!
George ( down=20 under)
I have missed the question.
Carbs get leaner near the top of their RPM ranges and use a = number of=20 tricks to maintain a reasonable F/A at high RPM. Even Webers = with a huge=20 number of emulsion tubes and jets for any imagined situation. If you = actually=20 remove the venturi (called the choke) from a carburetor it no longer = will=20 develop any differential pressure, and no fuel will flow through it. =
None is way too lean.
More like the Bendix dribble fuel injection that is based on a = positive=20 displacement pump geared to the engine. It just pees fuel all of the = time.=20 Crude but effective.
 
In many cases of a slide and needle type of carb, the edges of = the slide=20 hole and the flat shelf the slide seals against, is more than enough=20 turbulence to form the choke. Like Posa, Stromberg, SU and any = motorcycle=20 carb. They all have chokes even though it is not obvious. 
 
A 12A dyno sheet shows 139.6 foot pounds of torque at 6,500  = RPM.=20 and 173.3 HP. This is an engine designed for 9,600 RPM shifting. This = has a=20 Weber carb has two 36MM chokes. Two 40MM chokes would be real nice. = Longer=20 runners would be better, so cruise RPM is also the peak torque or a = bit above=20 peak.
 
Lynn E. Hanover 



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Version: 7.5.484 / Virus Database: 269.12.0/959 - Release = Date:=20 17/08/2007 5:43 PM
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