X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 936558 for flyrotary@lancaironline.net; Sun, 08 May 2005 14:42:48 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-189-178.carolina.res.rr.com [24.74.189.178]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j48Ig00W023188 for ; Sun, 8 May 2005 14:42:01 -0400 (EDT) Message-ID: <001b01c553fd$a707ba60$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: 4-port intake measurements Date: Sun, 8 May 2005 14:42:14 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0018_01C553DC.1FBCE1F0" 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-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0018_01C553DC.1FBCE1F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageI have given some thought to the idea you mentioned. I am not = certain what the results would be. Here are some thoughts on the topic. The two primary tubes would create intake pulses every 60 deg rotary (or = 180 deg e shaft) revolution. Same for the secondaries. The primary and = secondary of the same rotor would be near simultaneous in sucking air. = So those two pulses I would think tend to reinforce each other. Now the = pulse theory states that when a FAW pulse hits an "Open" (relative = speaking) it reflects an opposite wave back down the tube. So if a = "negative" pulse hits the TB opening, then it would reflect a positive = wave (helping to push the air toward the intake). However that wave = could be opposing the following set of pulses which it could interfere = with. So would have to do some calculations to see how long the = manifold would need to be at some rpm (high I presume) such that the = positive reflected wave would reach the intake port area in time to help = shove more air in - before running into the next pair of pulses in the = tube. =20 No! No! no more manifolds (at least not this summer {:>)) Well, maybe a = few calculations. Lets see - at 6000 rpm the rotation period of the rotor is 60/2000 =3D = .03 sec =3D 30 millsec. 6 pulses created(one for each of the 3 faces = *2) during each revolution so we have 30/6 =3D 5 millisec between each = pulse sets. If you assume sea level speed of sound approx 1100 ft/sec, = then for a pulse to be generated by the intake opening, travel to the TB = and back to the next set of intake port openings would be approx .005* = 1100 =3D 5.5 ft. or 1/2 of that for length of runner (trip one way and = trip back) =3D 2.5 ft or apprx 29". But that was at 6000 rpm and 1100 = fps. =20 For 7000 rpm 60/3500 =3D .017 sec. .017/6 =3D .00286 sec or 2.86 = millsec. .00286 *1100 =3D 3.14 ft or 1/2 of that would be 1.5 ft or = 18" for a runner length, at least if my math is correct. This is only = an approximation but should give you an idea of lengths. Ed =20 ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Sunday, May 08, 2005 1:07 PM Subject: [FlyRotary] Re: 4-port intake measurements When I combined my primary and secondary on one of my intake designs I = used a 1.75" dia tube, so sounds like your dimensions closely agree. I = currently have a 1 1/2 and 1 1/4 for the secondary and primary = respectively. So that gives me a total of 2.99 sq inch runner area per = rotor. So approx .45 sq inches more per rotor than you currently have, = so I would say your current design could be restrictive. Thanks Ed, That's pretty much my conclusion too. While it's = certainly making good power, it could clearly be better, so it's = probably worth the hassle of making another intake. =20 I'm not sure if we ever cleared up this business about whether you = need a single TB big to allow for both rotors, or just one at a time. = That was at the heart of the Ellison debate. Interestingly, if you add = the sizes of the ports on both rotors, it comes to an equivalent tube of = about 63mm ID, which is right in line with the recent discussion of TB = sizes. =20 Here's another wacky idea for your entertainment- I'm familiar with = the scavenging concept used in exhaust systems. For one bank of a V-8, = you start with 4 pipes, then combine them to two bigger pipes, and = finally one even bigger pipe. The thought is that active flow from one = pipe is creating a suction on the others to help pull out exhaust of a = cylinder that's almost done with it's exhaust cycle. =20 Will this work in reverse? It almost seems like it would to me. What = would happen if you start with two primaries, and two secondaries, then = combine them to make two larger pipes (one for each rotor), then combine = again for a single larger pipe with a TB on the end of it? =20 Cheers, Rusty (more power Scotty) ------=_NextPart_000_0018_01C553DC.1FBCE1F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
I have given some thought to the idea = you=20 mentioned.  I am not certain what the results would be.  Here = are some=20 thoughts on the topic.
 
The two primary tubes would create = intake pulses=20 every 60 deg rotary (or 180 deg e shaft) revolution.  Same for the=20 secondaries.  The primary and secondary of the same rotor would be = near=20 simultaneous in sucking air.  So those two pulses I would think = tend to=20 reinforce each other.  Now the pulse theory states that when = a FAW=20 pulse hits an "Open" (relative speaking) it reflects an opposite wave = back down=20 the tube.  So if a "negative" pulse hits the TB opening, then it = would=20 reflect a positive wave (helping to push the air toward the = intake). =20 However that wave could be opposing the following set of pulses = which it=20 could interfere with.  So would have to do some calculations to see = how=20 long the manifold would need to be at some rpm (high I presume) such = that the=20 positive reflected wave would reach the intake port area in = time to=20 help shove more air in - before running into the = next pair of=20 pulses in the tube.  
 
No! No! no more manifolds (at = least not this=20 summer {:>))  Well, maybe a few calculations.
 
Lets see - at 6000 rpm the rotation = period of the=20 rotor is 60/2000 =3D .03 sec =3D 30 millsec.  6 pulses created(one = for each of=20 the 3 faces *2)  during each revolution so we have 30/6 =3D 5 = millisec=20 between each pulse sets.  If you assume sea level speed of sound = approx=20 1100 ft/sec, then for a pulse to be generated by the intake opening, = travel to=20 the TB and back to the next set of intake port openings would be approx = .005*=20 1100 =3D 5.5 ft. or 1/2 of that for length of runner (trip one way and = trip back)=20 =3D 2.5 ft or apprx 29".  But that was at 6000 rpm and 1100 = fps. =20
 
For 7000 rpm 60/3500 =3D .017 = sec.   .017/6=20 =3D .00286 sec or 2.86 millsec.   .00286 *1100 =3D 3.14 ft or = 1/2 of that=20 would be 1.5 ft or 18" for a runner length, at least if my math is=20 correct.  This is only an approximation but should give you an idea = of=20 lengths.
 
 
Ed 
 
 
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Sunday, May 08, 2005 1:07 = PM
Subject: [FlyRotary] Re: 4-port = intake=20 measurements

When I = combined my=20 primary and secondary on one of my intake designs I used a 1.75" dia = tube,=20 so sounds like your dimensions closely agree.  I currently = have a 1=20 1/2 and 1 1/4 for the secondary and primary respectively.  So = that gives=20 me a total of 2.99 sq inch runner area per rotor. So approx .45 sq = inches more=20 per rotor than you currently have, so I would say your current design = could be=20 restrictive.
 
 
Thanks=20 Ed,  That's pretty much my conclusion too.  While it's = certainly=20 making good power, it could clearly be better, so it's = probably=20 worth the hassle of making another = intake.  
 
I'm not=20 sure if we ever cleared up this business about whether you need a = single=20 TB big to allow for both rotors, or just one at a = time.  That was at=20 the heart of the Ellison debate.  Interestingly, if you add the=20 sizes of the ports on both rotors, it comes to an equivalent tube = of=20 about 63mm ID, which is right in line with the recent discussion = of TB=20 sizes.  
 
Here's=20 another wacky idea for your entertainment- I'm familiar with=20 the scavenging concept used in exhaust systems.  For = one bank=20 of a V-8, you start with 4 pipes, then combine them to two = bigger=20 pipes, and finally one even bigger pipe.  The thought is=20 that active flow from one pipe is creating a suction on the = others to=20 help pull out exhaust of a cylinder that's almost done with it's = exhaust=20 cycle. 
 
Will this=20 work in reverse?  It almost seems like it would to = me.  What=20 would happen if you start with two primaries, and two = secondaries, then=20 combine them to make two larger pipes (one for each rotor), then = combine again=20 for a single larger pipe with a TB on the end of=20 it?     
 
Cheers,
Rusty (more=20 power Scotty)
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