X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail35.syd.optusnet.com.au ([211.29.133.51] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTPS id 2269811 for flyrotary@lancaironline.net; Fri, 17 Aug 2007 21:30:17 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.133.51; envelope-from=lendich@optusnet.com.au Received: from george (d58-108-92-62.dsl.nsw.optusnet.com.au [58.108.92.62]) by mail35.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l7I1TXbn031062 for ; Sat, 18 Aug 2007 11:29:34 +1000 Message-ID: <001801c7e137$3cad26e0$3e5c6c3a@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Air/fuel flow Date: Sat, 18 Aug 2007 11:29:34 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0015_01C7E18B.0D791010" 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_0015_01C7E18B.0D791010 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Kelly, That's interesting - is Ed trying to tell me something? Just joking, I did know that but didn't relate the two. George ( down under) George, Not Ed and not great at math but from my skydiving days the figure of 176 feet per sec (approx 120 mph) is called terminal velocity for = the average human body in a flat stable freefall position........Just a = bit of trivia......... -- Kelly Troyer=20 "Dyke Delta"_13B ROTARY Engine=20 "RWS"_RD1C/EC2/EM2=20 "Mistral"_Backplate/Oil Manifold=20 -------------- Original message from "George Lendich" = : --------------=20 Ed, I would like to clarify another point and that is your = velocity figure of 120 mph. I will explain:- I have studied carb sites for snippets of information ( they = don't give much away), however one did say that carb choke speeds are = usually 450' per second and racing cars 125' per second. I assume the racing car inlet speeds are lower because the = throttle is wide open with massive sized inlets, therefore lower vacuum = signal. Your calculations use 176' per second. Can you clarify where = you acquired that figure from as a higher figure would reduce the inlet = area calculations. The carb I am looking at is the Revmaster, they currently only = have 40mm carbs available due to slow demand of the 42/44mm. One good = thing is that the carb operates without a need of venturi, however the = vacuum signal must be weaker ( because of this)coupled with a weaker = signal because of the shape of the rotor face.=20 At the very least the lack of venturi also eliminates the = choke potential. Some carbs have a 44mm inlet but are choked to 36mm = which would increase inlet speed (good), but as you say, may move into = the choke restriction area (bad). A weaker signal would also effect the idle mixture as this is = driven by vacuum rather than air flow, however I guess this can be = adjusted manually. Should be plenty of vacuum at idle with the slide = closed. 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) Well I'll be Ed, 2.4137sq" =3D (.877x.877xPi =3D 2.416), therefore .877 Radius = or 1.754 Dia or 44.55 mm for the carb opening. I'm working on the rest! George ( down under) For inlet, you take the CFM and you need one other factor - = what velocity do you want through your inlet? Lets say you want a = higher velocity of around 176 feet/sec (120 MPH) then we know that = Volume =3D Area * length. If were want 176 feet/sec velocity from 176 = CFM air flow then coverting CFM to cubic feet per second were have = 176Ft^3/min / 60 Second/Minute =3D 29.333 Ft^3/ Second -------------------------------------------------------------------------= ----- 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_0015_01C7E18B.0D791010 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Kelly,
That's interesting - is Ed trying to = tell me=20 something?
Just joking, I did know that but didn't = relate the=20 two.
George ( down under)
George,
    Not Ed and not great at math but from my = skydiving=20 days the figure
of 176 feet per sec (approx 120 mph) is called terminal velocity = for=20 the
average human body in a flat stable = freefall position........Just a=20 bit of
trivia.........
--
Kelly Troyer
"Dyke = Delta"_13B=20 ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil = Manifold=20




--------------=20 Original message from "George Lendich" = <lendich@optusnet.com.au>:=20 --------------

 
Ed,
 I would like to clarify = another=20 point and that is your velocity figure of 120 = mph.
 
I will explain:-
 
I have studied carb = sites for=20 snippets of information ( they don't give much away), however = one did=20 say that carb choke speeds  are usually 450' per = second and=20 racing cars 125' per second.
 
I assume the racing car inlet = speeds are=20 lower because the throttle is wide open with massive sized = inlets,=20 therefore lower vacuum signal.
 
Your calculations use 176' = per second.=20 Can you clarify where you acquired that figure from as a = higher figure=20 would reduce the inlet area calculations.
 
The carb I am looking at is = the=20 Revmaster, they currently only have 40mm carbs available due = to slow=20 demand of the 42/44mm. One good thing is that the carb = operates=20 without a need of venturi, however the vacuum signal = must be=20 weaker ( because of this)coupled with a weaker signal because = of the=20 shape of the rotor face.
 
At the very least the lack of = venturi=20 also eliminates the choke potential. Some carbs have a 44mm = inlet but=20 are choked to 36mm which would increase inlet speed (good), = but as you=20 say, may move into the choke restriction area = (bad).
 
A weaker signal would also = effect the=20 idle mixture as this is driven by vacuum rather than air flow, = however=20 I guess this can be adjusted manually. Should be plenty of = vacuum at=20 idle with the slide closed.
 
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=20 would be greatly appreciated.
 
Also my research indicates = that flow air/=20 fuel mix richens at higher RPM and altitude. I can't = remember why=20 at higher RPM - mind block, however for altitude it = is because=20 fuel flow is driven by air flow and even though the = density of=20 the air is lower ( at altitude) the flow remains the same - = therefore=20 richer mixture. Revmaster says their needle design is self = leaning (=20 to a degree) because of design. I assume because the air = density=20 directly affects the suction to the rear side of the flat = ground=20 needle, ( this provides the low pressure area rather than the=20 venturi) therefore with reduced density you have reduced = suction=20 and reduced fuel and leaner mixture. However I will = clarify that=20 when next we talk.
I find this all very=20 interesting!
George ( down = under)
 
 
 
Well I'll be Ed,
2.4137sq" =3D (.877x.877xPi = =3D 2.416),=20 therefore .877 Radius or 1.754 Dia or 44.55 mm for the carb=20 opening.
I'm working on the = rest!
George ( down = under)
 
For inlet, you take the CFM and you = need one=20 other factor - what velocity do you want through your = inlet? =20 Lets say you want a higher velocity of around 176 feet/sec = (120=20 MPH)  then we know that Volume =3D Area * length.  = If were=20 want 176 feet/sec velocity from 176 CFM air flow then = coverting CFM to=20 cubic feet per second were have 176Ft^3/min / 60 Second/Minute = =3D=20 29.333 Ft^3/=20 = Second

No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.484 / Virus Database: 269.12.0/959 - Release = Date:=20 17/08/2007 5:43 PM
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