Return-Path: Received: from mailout2.pacific.net.au ([61.8.0.85] verified) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP id 725330 for flyrotary@lancaironline.net; Fri, 11 Feb 2005 14:14:58 -0500 Received-SPF: none receiver=logan.com; client-ip=61.8.0.85; envelope-from=peon@pacific.net.au Received: from mailproxy2.pacific.net.au (mailproxy2.pacific.net.au [61.8.0.87]) by mailout2.pacific.net.au (8.12.3/8.12.3/Debian-7.1) with ESMTP id j1BJEAHn027469 for ; Sat, 12 Feb 2005 06:14:10 +1100 Received: from ar1 (ppp242B.dyn.pacific.net.au [61.8.36.43]) by mailproxy2.pacific.net.au (8.12.3/8.12.3/Debian-7.1) with SMTP id j1BJE8Gf011885 for ; Sat, 12 Feb 2005 06:14:08 +1100 Message-ID: <004301c5106d$66f9be10$2b24083d@ar1> From: "Leon" To: "Rotary motors in aircraft" References: Subject: Number Running and Pre -Suppositions was Re: [FlyRotary] Re: Last Word on Displacement Date: Sat, 12 Feb 2005 06:10:50 +1100 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0040_01C510C9.99E21A50" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 This is a multi-part message in MIME format. ------=_NextPart_000_0040_01C510C9.99E21A50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Al, Yep, I agree!! I think we actually nailed this one down on ACRE years = ago (before I got ex-communicated). But "Da Boyz" do tend to get = carried away with the maths. However, the maths must be applied = correctly, with strict attention to analysing the problem first. This = Displacement controvesy is just another example of not making sure that = the fundamental premises and pre-suppositions are correct before = embarking on that murky enterprise of "Number Running" (Shades of the = EWP fracas!!). Many years ago, my dear old mentor told me "Leon, an internal = combustion engine is nothing except an air pump, ... gone mad". That = really changed my mindset. So if you know how much air it pumps per = cycle, you can compare it to any other air pump. This is where = volumetric efficiency, and the type of cycle (2 stroke, 4 stroke, = Wankel etc) comes into the picture. =20 Additionally, displacement and air flow are not necessarily the same = thing - RPM comes into it, as well as Vol Eff. However, in the final = analysis, all that really matters for aircraft use is how much power = can be extracted and at what RPM, and how efficiently the fuel is = burned (BSFC- which is another boondoggle altogether - not going there = today!!). So as for this issue of comparing a 13B to a Lyc 360, using current = technology done right, either an REW (with 9.7:1 high comp rotors) or a = Renesis 13B (with 10:1 rotors) will make over 200 BHP, as long the = engine is allowed to rev to where it makes MAX RPM, Which is just a = function of PSRU ratio, prop size etc (7,000 RPM min - whereas the Lyc = will do a pretty fair impersonation of a grenade if it goes over 3,000 = RPM for long). . =20 Obviously the manifolding (inlet and exhaust), and port timing (mild = port, bridgeport, PP etc) must also be conducive to the airflow = required to make that power. None of this is a real mystery as there is = nearly 40 years of world wide racing experience to define sizes and = lengths, RPM and power outputs. There is NO need to re-invent the = wheel. Cheers, Leon ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Saturday, February 12, 2005 2:58 AM Subject: [FlyRotary] Re: Last Word on Displacement was Re: [FlyRotary] = Solved!!!! =3D> Rotary AirFlow Equation? Help? Thank you; Leon. That's how I had always looked at it; but with all the math spinning = about, I thought maybe I had overlooked something. Al ------=_NextPart_000_0040_01C510C9.99E21A50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Al,
 
Yep, I agree!!  I think we=20 actually nailed this one down on ACRE years ago (before I got=20 ex-communicated).  But "Da Boyz" do tend to get carried away with = the=20 maths. However,  the maths must be applied correctly,  = with=20 strict attention to analysing the problem first.  This Displacement = controvesy is just another example of not making sure that the = fundamental=20 premises and pre-suppositions are correct before embarking on that murky = enterprise of  "Number Running"  (Shades of the EWP=20 fracas!!).
 
Many years ago,  my dear old = mentor told me=20 "Leon,  an internal combustion engine is nothing except an air = pump,=20 ... gone mad". That really changed my mindset.  So if you = know=20 how much air it pumps per cycle,  you can compare it to any other = air=20 pump.  This is where volumetric efficiency,  and the type of = cycle (2=20 stroke,  4 stroke,  Wankel etc) comes into the=20 picture. 
 
Additionally,  displacement and = air flow are=20 not necessarily the same thing - RPM comes into it, as well as Vol = Eff. =20 However,  in the final analysis,  = all that=20 really matters for aircraft use is how much power can be extracted = and at=20 what RPM,  and how efficiently the fuel is burned (BSFC- which is = another=20 boondoggle altogether -  not going there = today!!).
 
So as for this issue of comparing a 13B = to a Lyc=20 360,  using  current technology done right,  either an = REW (with=20 9.7:1 high comp rotors) or a Renesis 13B (with 10:1 rotors) will = make over=20 200 BHP,  as long the engine is allowed to rev to where it makes = MAX=20 RPM,   Which is just a function of PSRU ratio,  prop size = etc (7,000 RPM min - whereas the Lyc will do a pretty fair = impersonation of=20 a grenade if it goes over 3,000 RPM for long). .  =
 
Obviously the manifolding (inlet and=20 exhaust), and port timing (mild port,  bridgeport,  = PP etc)=20 must also be conducive to the airflow required to make that power.  = None of=20 this is a real mystery as there is nearly 40 years of world wide racing=20 experience to define sizes and lengths,  RPM and power = outputs.  There=20 is NO need to re-invent the wheel.
 
Cheers,
 
Leon
----- Original Message -----
From:=20 Al = Gietzen=20
Sent: Saturday, February 12, = 2005 2:58=20 AM
Subject: [FlyRotary] Re: Last = Word on=20 Displacement was Re: [FlyRotary] Solved!!!! =3D> Rotary AirFlow = Equation?=20 Help?

Thank you; = Leon.

That=92s how I had = always looked=20 at it; but with all the math spinning about, I thought maybe I had = overlooked=20 something.

 

Al

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