X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from web83902.mail.sp1.yahoo.com ([69.147.92.99] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with SMTP id 3455218 for flyrotary@lancaironline.net; Tue, 27 Jan 2009 13:03:20 -0500 Received: (qmail 15557 invoked by uid 60001); 27 Jan 2009 18:03:21 -0000 X-YMail-OSG: xpvHSrMVM1mpDjo0QW6Bh.MGCNScGn_1tSwC_Apt6IwPg.2HiEuabFdP Received: from [76.237.105.201] by web83902.mail.sp1.yahoo.com via HTTP; Tue, 27 Jan 2009 10:03:20 PST X-Mailer: YahooMailWebService/0.7.260.1 Date: Tue, 27 Jan 2009 10:03:20 -0800 (PST) From: James Maher Reply-To: delta11xd@att.net Subject: Re: [FlyRotary] Street ports for airplanes To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-138740486-1233079400=:13953" Message-ID: <252559.13953.qm@web83902.mail.sp1.yahoo.com> --0-138740486-1233079400=:13953 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Would a street port for an airplane be called... an airport? Just wondering. =A0 JIm --- On Tue, 1/27/09, Lynn Hanover wrote: From: Lynn Hanover Subject: [FlyRotary] Street ports for airplanes To: "Rotary motors in aircraft" Date: Tuesday, January 27, 2009, 11:19 AM Yes, the airplane application begs for a port job. Constant RPM. Long runs.= A good choice of inlet lengths. I would not early open enough to drop the trailing end of the side seal. An= d no more than maybe 65 degrees ATDC closing. Radius all edges of the port = so no wear problems.=20 =A0 The street port suggests that it is a good choice for use on the street. Th= at is not actually true in many cases. In the street port the side of the p= ort is cut away to expose more of the runner side wall, and thus open the p= ort sooner (early open the intake port) just like a cam shaft in a piston e= ngine. The rotor would be moving to the left as it rotates.=20 =A0 The two lines are the actual paths of the trailing end of the side seal on = the left. And, the leading end of the side seal on the right. In this pictu= re there is a port cut through the runner wall on the right and the bridge = with the line on it supports the sides seal leading end and the corner seal= as it crosses the port, like a bridge. So this port scheme is called a "Br= idge Port". So, for a street port you just leave out the port on the right.= Bridgeports make best power above 8,000 RPM.=A0 =A0 So, a street port can can be made to open so early that the trailing end of= the seal drops into the port during operation. As you can see here. The ar= row shows where the corner of the seal steps back up onto the bridge as it = moves upward. This rounds the corner off of the seal and reduces compressio= n. But racers don't care about that. (I do, and change the ports to elimina= te this problem)=A0but most don't care because they are inside the engine c= hanging seals every 8 hours or=A0so anyway. Probably not a good selling poi= nt for aircraft use. =A0 So the right side in this picture is the open side. Further right =3Dmore d= uration. Or, longer open time for the port. The top edge of the port determ= ines the closing point. Typical closing point would be 50 degrees after=A0b= ottom dead center, or, 50 ABDC. This sounds very modest to a piston person,= but the=A0degree wheel is on the crank as it would be in a piston engine, = and those guys want to hear more like 75 degrees after=A0bottom dead center= or, 75 ABDC for a closing point.=A0 =A0 However the rotor moves slowly compared to the crank, and our 50 degrees is= better than their 75 degrees. =A0 Anyway, we can move the closing point to make closing later than stock (50 = ABDC) and it is the same as a late closing cam in the piston engine. My bri= dge ports close at 85 degrees after top dead center, or, 85 ABDC. This woul= d be useless in an airplane, but is dynamite above 8,000 RPM. Actually 245 = HP at 9,400 RPM from a 12A. So a street port that closes at perhaps 60 degr= ees or 65 degrees at the most ABDC would be a great big help for airplane u= se. Remember less is more when porting. Use a port mask from the pros. Thre= e layers of duct tape around the outside of the scribe lines. Make sure the= trailing end of the side seal is supported. =A0 =A0If you need iron, take a pill. Breathing cast iron dust will kill you. A= really good die grinder can take off a thumb nail so fast you wont even no= tice it for a few seconds.=A0 =A0 Read Paul Yaws tech articles. www.yawpower.com =A0 The difference between a=A0great street port and a really heavy paper weigh= t is 1/16".=A0 Wear welding gloves on both hands and safety glasses from a name brand. Wea= r those cover goggles over the glasses. Set up a fan to blow across the wor= k to help keep slivers away from you.=A0=A0 =A0 It escaped me for years how to fit open and close events onto a rotary. I w= as a piston person with my own dyno. Even looking at some of the "Explanati= ons" I=A0didn't get it.=A0 =A0 Here it is in easy to understand terms. =A0 In a Piston Engine: The piston at the top of the bore is TDC (top dead center) There are two of= those. One during compression and one during overlap. The piston at the bo= ttom of the bore is BDC (bottom dead center). There are two of those. One a= t the bottom of the power stroke, and one at the bottom of the intake strok= e. Note that the two TDCs and the two BDCs are in the same place each time.= This is a 4 stroke Otto cycle engine just like a rotary. =A0 In the Rotary Engine: In the rotary all of the same 4 stroke stuff happens as above. There are tw= o TDCs and two BDCs but they are in=A0DIFFERENT places. The smallest volume= is when two corner seals are on a vertical line. When this is beside the p= lugs it is TDC on the power stroke. When beside the exhaust port/intake por= t it is TDC in overlap.=A0 =A0 =A0Minimum volume=3DTDC. =A0 The largest volume is when any two corner seals are on a horizontal line. W= hen this is at the bottom of the housing next to the oil pan, it is BDC in = the exhaust cycle. When this at the top of the housing it is BDC on the int= ake cycle.=20 =A0 Maximum volume=3DBDC =A0 The open and close events for ports are called out from the nearest TDC or = BDC to minimise confusion. This is because it takes=A01080 degrees in a rotary and only 720 degrees in= a piston engine.=20 =A0 Lynn E. Hanover =A0 =A0=A0=A0 =A0 =A0-- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.= html --0-138740486-1233079400=:13953 Content-Type: text/html; charset=us-ascii
Would a street port for an airplane be called... an airport?
Just wondering.
 
JIm

--- On Tue, 1/27/09, Lynn Hanover <lehanover@gmail.com> wrote:
From: Lynn Hanover <lehanover@gmail.com>
Subject: [FlyRotary] Street ports for airplanes
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Tuesday, January 27, 2009, 11:19 AM

Yes, the airplane application begs for a port job. Constant RPM. Long runs. A good choice of inlet lengths.
I would not early open enough to drop the trailing end of the side seal. And no more than maybe 65 degrees ATDC closing. Radius all edges of the port so no wear problems.
 
The street port suggests that it is a good choice for use on the street. That is not actually true in many cases. In the street port the side of the port is cut away to expose more of the runner side wall, and thus open the port sooner (early open the intake port) just like a cam shaft in a piston engine. The rotor would be moving to the left as it rotates.
 
The two lines are the actual paths of the trailing end of the side seal on the left. And, the leading end of the side seal on the right. In this picture there is a port cut through the runner wall on the right and the bridge with the line on it supports the sides seal leading end and the corner seal as it crosses the port, like a bridge. So this port scheme is called a "Bridge Port". So, for a street port you just leave out the port on the right. Bridgeports make best power above 8,000 RPM. 
 
So, a street port can can be made to open so early that the trailing end of the seal drops into the port during operation. As you can see here. The arrow shows where the corner of the seal steps back up onto the bridge as it moves upward. This rounds the corner off of the seal and reduces compression. But racers don't care about that. (I do, and change the ports to eliminate this problem) but most don't care because they are inside the engine changing seals every 8 hours or so anyway. Probably not a good selling point for aircraft use.
 
So the right side in this picture is the open side. Further right =more duration. Or, longer open time for the port. The top edge of the port determines the closing point. Typical closing point would be 50 degrees after bottom dead center, or, 50 ABDC. This sounds very modest to a piston person, but the degree wheel is on the crank as it would be in a piston engine, and those guys want to hear more like 75 degrees after bottom dead center or, 75 ABDC for a closing point. 
 
However the rotor moves slowly compared to the crank, and our 50 degrees is better than their 75 degrees.
 
Anyway, we can move the closing point to make closing later than stock (50 ABDC) and it is the same as a late closing cam in the piston engine. My bridge ports close at 85 degrees after top dead center, or, 85 ABDC. This would be useless in an airplane, but is dynamite above 8,000 RPM. Actually 245 HP at 9,400 RPM from a 12A. So a street port that closes at perhaps 60 degrees or 65 degrees at the most ABDC would be a great big help for airplane use. Remember less is more when porting. Use a port mask from the pros. Three layers of duct tape around the outside of the scribe lines. Make sure the trailing end of the side seal is supported.
 
 If you need iron, take a pill. Breathing cast iron dust will kill you. A really good die grinder can take off a thumb nail so fast you wont even notice it for a few seconds. 
 
Read Paul Yaws tech articles. www.yawpower.com
 
The difference between a great street port and a really heavy paper weight is 1/16". 
Wear welding gloves on both hands and safety glasses from a name brand. Wear those cover goggles over the glasses. Set up a fan to blow across the work to help keep slivers away from you.  
 
It escaped me for years how to fit open and close events onto a rotary. I was a piston person with my own dyno. Even looking at some of the "Explanations" I didn't get it. 
 
Here it is in easy to understand terms.
 
In a Piston Engine:
The piston at the top of the bore is TDC (top dead center) There are two of those. One during compression and one during overlap. The piston at the bottom of the bore is BDC (bottom dead center). There are two of those. One at the bottom of the power stroke, and one at the bottom of the intake stroke. Note that the two TDCs and the two BDCs are in the same place each time. This is a 4 stroke Otto cycle engine just like a rotary.
 
In the Rotary Engine:
In the rotary all of the same 4 stroke stuff happens as above. There are two TDCs and two BDCs but they are in DIFFERENT places. The smallest volume is when two corner seals are on a vertical line. When this is beside the plugs it is TDC on the power stroke. When beside the exhaust port/intake port it is TDC in overlap. 
 
 Minimum volume=TDC.
 
The largest volume is when any two corner seals are on a horizontal line. When this is at the bottom of the housing next to the oil pan, it is BDC in the exhaust cycle. When this at the top of the housing it is BDC on the intake cycle.
 
Maximum volume=BDC
 
The open and close events for ports are called out from the nearest TDC or BDC to minimise confusion.
This is because it takes 1080 degrees in a rotary and only 720 degrees in a piston engine.
 
Lynn E. Hanover
 
   
 
 
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