Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP id 723423 for flyrotary@lancaironline.net; Thu, 10 Feb 2005 08:40:11 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.rr.com [24.74.185.127]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j1ADdNbo024377 for ; Thu, 10 Feb 2005 08:39:23 -0500 (EST) Message-ID: <002301c50f75$f0482f60$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Same HP = Same Air Mass <> same air Velocity [FlyRotary] Re: ... Date: Thu, 10 Feb 2005 08:39:26 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0020_01C50F4C.0736A500" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0020_01C50F4C.0736A500 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks for the contribution, Bill, point well made. Clearly there are many aspects to induction (libraries written on the = reciprocating engine ) and the complex interaction of different forces = in induction systems makes any discussion which promotes understanding = of the rotary useful. I have tried short intakes and long intakes on my = turbo 4 port (no turbo) and there is no question in my mind that at = least in the 4500 - 6500 range longer is better. Now clearly as you go = up in rpm shorter tubes provide all the attributes you describe. Sure = wish my engine would respond to 3-5 inch inlet tracks {:>). Ed ----- Original Message -----=20 From: WRJJRS@aol.com=20 To: Rotary motors in aircraft=20 Sent: Thursday, February 10, 2005 12:56 AM Subject: [FlyRotary] Re: Same HP =3D Same Air Mass <> same air = Velocity [FlyRotary] Re: ... In a message dated 2/9/2005 7:00:00 PM Pacific Standard Time, = eanderson@carolina.rr.com writes: So if the rotary has less displacement of the sucking component and = must take 25% longer for each revolution. Therefore the only way it can = obtain an equal amount of air is for the intake air to have a higher = velocity than the Lycoming does. The air velocity of the area in the intake for the rotary would = appear to have to be much higher than the Lycoming. If my assumptions = and calculations are correct that would imply (at least to me) that to = minimize air flow restriction a larger opening would be required on the = rotary compared to the same HP Lycoming. Its not that one is taken in = more air its that the rotary has less time and smaller displacement pump = so must take in the air at a higher velocity Ed, you have a good cut on the discussion, with one other variant to = add in. There is flow stopage in the rotary in the overlap phase so the = easiest way for the tuning to work is low restriction. You can use a = single throttle body but it better be a big one. Air has mass which is = why tuning works at all. The correct length inlet tube keeps the air = moving toward the chamber durring the overlap phase. You are right on = about the timing which is why a no-compromise intake like the Le Mans = engine uses the variable length inlets that get shorter at high RPMs. = The shorter time to cram in the air, (higher RPM), the less restriction = you must have to extract the most out of the engine. On the latest F1 = engines 18K RPM is common, that's why they have an intake tract about = 3-5 inches long. They started the showerhead style injection because the = length is so short that shooting across the plenum allowed milliseconds = longer for the fuel to vaporize. Pretty extreem stuff. Your comments = about rotor speed also indicated why we need longer intakes than piston = engines for the same shaft RPM. The rotor turns slower than the E-shaft = so our intake event is like a piston engine turnig over slower. Bill Jepson ------=_NextPart_000_0020_01C50F4C.0736A500 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Thanks for the contribution, Bill, point well made.
 
Clearly there are many aspects to induction (libraries written on = the=20 reciprocating engine ) and the complex interaction of different forces = in=20 induction systems makes any discussion which promotes understanding of = the=20 rotary useful.  I have tried short intakes and long intakes on my = turbo 4=20 port (no turbo) and there is no question in my mind that at least = in the=20 4500 - 6500 range longer is better.  Now clearly as you go up in = rpm=20 shorter tubes provide all the attributes you describe.  Sure wish = my engine=20 would respond to 3-5 inch inlet tracks {:>).
 
Ed
----- Original Message -----
From:=20 WRJJRS@aol.com
Sent: Thursday, February 10, = 2005 12:56=20 AM
Subject: [FlyRotary] Re: Same = HP =3D Same=20 Air Mass <> same air Velocity [FlyRotary] Re: ...

In a message dated 2/9/2005 7:00:00 PM Pacific Standard Time, eanderson@carolina.rr.com=20 writes:
So if the rotary has less = displacement of the=20 sucking component and must take 25% longer for each = revolution. =20 Therefore the only way it can obtain an equal amount of air is for = the=20 intake air to have a higher velocity than the Lycoming=20 does.
 
The air velocity of the area in the = intake for=20 the rotary would appear to have to be much higher than the = Lycoming. =20 If my assumptions and calculations are correct that would imply (at = least to=20 me) that to minimize air flow restriction a larger opening = would be=20 required on the rotary compared to the same HP Lycoming.  = Its not=20 that one is taken in more air its that the rotary has less time and = smaller=20 displacement pump so must take in the air at a higher=20 velocity
Ed, you have a good cut on the discussion, with one other variant = to add=20 in. There is flow stopage in the rotary in the overlap phase so the = easiest=20 way for the tuning to work is low restriction. You can use a single = throttle=20 body but it better be a big one. Air has mass which is why tuning = works at=20 all. The correct length inlet tube keeps the air moving toward the = chamber=20 durring the overlap phase. You are right on about the timing which is = why a=20 no-compromise intake like the Le Mans engine uses the variable length = inlets=20 that get shorter at high RPMs. The shorter time to cram in the air, = (higher=20 RPM), the less restriction you must have to extract the most out of = the=20 engine. On the latest F1 engines 18K RPM is common, that's why they = have an=20 intake tract about 3-5 inches long. They started the showerhead style=20 injection because the length is so short that shooting across the = plenum=20 allowed milliseconds longer for the fuel to vaporize. Pretty extreem = stuff.=20 Your comments about rotor speed also indicated why we need longer = intakes than=20 piston engines for the same shaft RPM. The rotor turns slower than the = E-shaft=20 so our intake event is like a piston engine turnig over slower.
Bill Jepson
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