X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtp109.sbc.mail.re2.yahoo.com ([68.142.229.96] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with SMTP id 2080136 for flyrotary@lancaironline.net; Sat, 02 Jun 2007 07:48:08 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.229.96; envelope-from=downing.j@sbcglobal.net Received: (qmail 42729 invoked from network); 2 Jun 2007 11:47:31 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=sbcglobal.net; h=Received:X-YMail-OSG:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=eYOgg6PEPxpIwwUWNi5ep0ZAzl5OOi87D7VCzWEpHNRi3rjm1Fml79G/ZLceoqauM5Zm+155268dPSo7LqWAKrjBmBTeeFfLXXi5+gJvg2MH8GfFIFhwEnlYHY7CsiOuhFf0BLJDmMmM1ER2gLRR5hKKDVU1s4msiNQvr/ZRo7A= ; Received: from unknown (HELO mom) (downing.j@sbcglobal.net@75.41.3.241 with login) by smtp109.sbc.mail.re2.yahoo.com with SMTP; 2 Jun 2007 11:47:30 -0000 X-YMail-OSG: 1SvX0vEVM1krqe4ljLs_B180tvXs53Pjwz2EZuhDmJeHUEmwA24IS_vNm65kzrtjqNsneH2rrrjSrvgveAoJ4azRa2ORe.1QNT3ScZVT4mvYgeDeqJgECGcPN7uccg-- Message-ID: <001b01c7a50c$10c6c0c0$4001a8c0@gateway.2wire.net> From: "John Downing" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: PP Ve??? was Re: Intake CFM air flow Date: Sat, 2 Jun 2007 07:49:23 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0018_01C7A4EA.8948CA60" 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_0018_01C7A4EA.8948CA60 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Jerry, Lynn's thoughts here should give you some things to muse in your = mind on your P-port experimenting. JohnD ----- Original Message -----=20 From: Lehanover@aol.com=20 To: Rotary motors in aircraft=20 Sent: Saturday, June 02, 2007 2:41 AM Subject: [FlyRotary] Re: PP Ve??? was Re: Intake CFM air flow In a message dated 6/1/2007 8:20:04 P.M. Eastern Daylight Time, = daval@iprimus.com.au writes: Hi Lynn, since the Pport has a 'near lack of reversions' which are the source = of=20 "organ pipe" tuning theory; would you say that Pport engine is a lot = less sensitive to "tuned length" than a side port engine? Or does the Pport overlap between exhaust and inlet also cause a=20 pulsation which enhances 'organ pipe' tuned length. I think this is what I wanted to ask :) As you can in see in pictures of the Le mans engine, great care was = taken to have the correct length of inlet tract for each RPM. The engine = was not used even close to its maximum RPM or HP. And it had 700 HP. = Having poor performance in the tuned area is not no performance, and = they went to great lengths to get as much as was possible.=20 Larger diameter tubes gets a poor peak tuned effect but flows better = from less drag. A smaller diameter tube gives a more profound tuned = effect but flows less outside of the tuned RPM because of drag. And = they had big tubes. But the Pport flows like a turbine and power is = limited by the strength of the pieces. The multi piece crank may have = been the limiting factor. They could have made a few changes and had 800 = HP with good reliability. But they wanted perfect reliability. The = Lemans cars are forced to have broad power bands because there is a low = RPM 1st gear corner and a 230 MPH straight, so they went for the wider = power band that all competitors must have.=20 In a fixed length situation, you can only tune for one RPM, and that = must be for cruise and still have enough mid range to get the prop and = plane into the cruise speed range. Up on the cam, or on the pipe. It is = not impossible to have a killer motor that will not pull hard enough to = get a dyno reading without going up to RPM (Minimum used for racing) = with no load on the dyno, because the lightest load cannot be pulled by = the engine. It might even be that you cruise at or near peak torque and = never get to peak HP. The other choice would be to cruise just above = peak HP.=20 I gear the car to pass through peak power well before the end of the = longest straight. So we are above best power RPM for much of the = distance. The driver could not get around that one. Once the drag is = equal to the available power the car goes no faster in any case.=20 It is the first car to its top speed that beats you to the other end, = and seldom the car with the highest top speed. Notice that dragsters = that are going for a top speed records use a taller gear than the normal = get there first gear (lower). =20 The highest HP is not the answer unless there is a variable prop = system to keep the engine near its best power. Not fun if it takes = constant attention on clime out to keep things going the right = direction. The other end of the scale is a broad power band that allows = clime with no thought of engine RPM and on a fixed pitch prop.=20 It is possible to stall a prop with a bit of extra power while sitting = still or while the plane is moving slowly in a takeoff attempt. Most = people never get to feel that one because at lower RPM there is not = enough power being produced. But the prop blade stalls the same as a = wing stalls. Angle of attack is the answer. The speed of the air passing = through the prop disc alters the effective angle of attack, on any prop = fixed or adjustable pitch. Of course it is more likely on a high pitched = fixed pitch prop. It is also counterintuitive to pull off a bit of = throttle to stop the stall on a take off roll.=20 So the tuning is not for the max HP but a broad band of power, mostly = to the south or lower than the maximum HP. A bit lower HP at the bottom = of the range is fine, and helps avoid the slipping prop (like spinning = the wheels) and as the speed comes up and more power can be absorbed by = the prop the RPM brings on more power.=20 So, straight tubes over curved tubes. Worse if fuel is injected before = the curve or with a carb at the very end. Longer tubes give a broader = band than shorter tubes. Smaller diameter tubes give a better effect = over a smaller range. A peaky cam effect. Long tubes work better at = lower RPM. Short tubes work better at higher RPM. Probably a tapered = tube of medium length would be fantastic, but difficult to manufacture. = No inter connection of the inlet tracts is used on Pport engines.=20 A smaller higher velocity port gives a wider band than a huge slower = flowing port.=20 A bigger port moves the peak power up the RPM band and is peaky. A = smaller port works over a wider range, and is less sensitive to tuned = length. I had a factory Pport housing and it had small "D" shaped ports = with the flat part on the bottom. So it opened quickly and closed = slowly. Later aftermarket Pports (Modified factory) had huge rectangular = ports you could stick your hands in. Those made the power between 9,000 = and 10,700. =20 Lynn E. Hanover -------------------------------------------------------------------------= ----- See what's free at AOL.com. ------=_NextPart_000_0018_01C7A4EA.8948CA60 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Jerry, Lynn's thoughts here should give you some = things to=20 muse in your mind on your P-port experimenting.  JohnD
----- Original Message -----
From:=20 Lehanover@aol.com
Sent: Saturday, June 02, 2007 = 2:41=20 AM
Subject: [FlyRotary] Re: PP = Ve??? was Re:=20 Intake CFM air flow

In a message dated 6/1/2007 8:20:04 P.M. Eastern Daylight Time, = daval@iprimus.com.au = writes:
Hi=20 Lynn,
since the Pport has a 'near lack of reversions' which are = the=20 source of
"organ pipe" tuning theory; would you say that Pport = engine is=20 a lot
less sensitive to "tuned length" than a side port=20 engine?

Or does the Pport overlap between exhaust and inlet = also=20 cause a
pulsation which enhances 'organ pipe' tuned = length.

I=20 think this is what I wanted to ask :)
As you can in see in pictures of the Le mans engine, great care = was taken=20 to have the correct length of inlet tract for each RPM. The engine was = not=20 used even close to its maximum RPM or HP. And it had 700 HP.  = Having poor=20 performance in the tuned area is not  no performance, and they = went to=20 great lengths to get as much as was possible.
 
Larger diameter tubes gets a poor peak tuned effect but flows = better from=20 less drag. A smaller diameter tube gives a more profound tuned effect = but=20 flows less outside of the tuned RPM because of drag.  And they = had big=20 tubes. But the Pport flows like a turbine and power is limited by the = strength=20 of the pieces. The multi piece crank may have been the limiting = factor. They=20 could have made a few changes and had 800 HP with good reliability. = But they=20 wanted perfect reliability. The Lemans cars are forced to have = broad=20 power bands because there is a low RPM 1st gear corner and a 230 MPH = straight,=20 so they went for the wider power band that all competitors = must=20 have.
 
In a fixed length situation, you can only tune for one RPM, and = that must=20 be for cruise and still have enough mid range to get the prop and = plane into=20 the cruise speed range. Up on the cam, or on the pipe. It is not = impossible to=20 have a killer motor that will not pull hard enough to get a dyno = reading=20 without going up to RPM (Minimum used for racing) with no load on the = dyno,=20 because the lightest load cannot be pulled by the engine. It might = even be=20 that you cruise at or near peak torque and never get to peak HP. =  The=20 other choice would be to cruise just above peak HP.
 
I gear the car to pass through peak power well before the end of = the=20 longest straight.  So we are above best power RPM for much = of the=20 distance. The driver could not get around that one. Once the drag is = equal to=20 the available power the car goes no faster in any case.
 
It is the first car to its top speed that beats you to the other = end, and=20 seldom the car with the highest top speed. Notice that dragsters that = are=20 going for a top speed records use a taller gear than the normal get = there=20 first gear (lower).  
 
The highest HP is not the answer unless there is a variable prop = system=20 to keep the engine near its best power. Not fun if it takes constant = attention=20 on clime out to keep things going the right direction. The other end = of the=20 scale is a broad power band that allows clime with no thought of = engine RPM=20 and on a fixed pitch prop.
 
It is possible to stall a prop with a bit of extra power while = sitting=20 still or while the plane is moving slowly in a takeoff = attempt. Most=20 people never get to feel that one because at lower RPM there is not = enough=20 power being produced. But the prop blade stalls the same as a wing = stalls.=20 Angle of attack is the answer. The speed of the air passing through = the prop=20 disc alters the effective angle of attack, on any prop fixed or = adjustable=20 pitch. Of course it is more likely on a high pitched fixed pitch prop. = It is=20 also counterintuitive to pull off a bit of throttle to stop the stall = on a=20 take off roll. 
 
So the tuning is not for the max HP but a broad band of power, = mostly to=20 the south or lower than the maximum HP. A bit lower HP at the = bottom of=20 the range is fine, and helps avoid the slipping prop (like spinning = the=20 wheels) and as the speed comes up and more power can be absorbed by = the prop=20 the RPM brings on more power.
 
So, straight tubes over curved tubes. Worse if fuel is injected = before=20 the curve or with a carb at the very end. Longer tubes give a broader = band=20 than shorter tubes. Smaller diameter tubes give a better effect = over a=20 smaller range. A peaky cam effect. Long tubes work better at lower = RPM. Short=20 tubes work better at higher RPM. Probably a tapered tube of medium = length=20 would be fantastic, but difficult to manufacture. No inter connection = of the=20 inlet tracts is used on Pport engines.
A smaller higher velocity port gives a wider band than a huge = slower=20 flowing port.
 
A bigger port moves the peak power up the RPM band and is peaky. = A=20 smaller port works over a wider range, and is less sensitive to tuned = length.=20 I had a factory Pport housing and it had small "D" shaped ports with = the flat=20 part on the bottom. So it opened quickly and closed slowly. Later = aftermarket Pports (Modified factory) had huge rectangular ports you = could=20 stick your hands in. Those made the power between 9,000 and 10,700.=20  
 
Lynn E. Hanover
 



See what's free at AOL.com.=20
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