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From: "Richard Sohn" <res12@fairpoint.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-3272631@logan.com>
Subject: Re: [FlyRotary] Re: single rotor performance
Date: Wed, 5 Nov 2008 13:17:01 -0600
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I think there are a few things that need clarification.=20

The lower RPM runs were not WOT! I just recorded those on the way up to =
WOT, all at the same prop pitch. Meaning the only significant data point =
is at 6000RPM, which I consider about static. For that reason, the power =
level at those lower RPM are more reflecting the prop power demand than =
anything else.

As to the RPM difference, It may have been 100 or 150 RPM higher on the =
long runner than on the short one(tach reading a bit iffy). There is =
some thing else I ran into. All previous tests I ran with the prop =
showed some intermittent prop noise, seemingly influenced by the wind =
condition at testing time. This noise is very stady with the long =
runner. It is acoustically so strong you think it is going to blow your =
brains out. I could barely stand it until the fuel flow meter =
stabilized.=20
I have observed that phenomenon with the same type or prop on the SOOB =
at static runups. It seems that the increased power produced with the =
long runner is consumed by a sudden drag increase in the prop. This prop =
may just not be suitable for that kind of tests.=20
I will do further tests with different prop pitch, where the noise issue =
is one thing I want to find out more.
I may have to look for another prop.

The MP is measured at the same location in both cases, about 1" from the =
rotor housing. The pressure is picked up through a .035 hole. I guess I =
should have said "MP" and not "MAP", sorry for that.


Generally I am not very inclined to do a lot more basic performance =
tests since the engine is already producing way more power than my test =
bed needs for flying.=20
But that may change as I get further down the road.=20

Richard Sohn
N2071U

  ----- Original Message -----=20
  From: Tracy Crook=20
  To: Rotary motors in aircraft=20
  Sent: Wednesday, November 05, 2008 9:09 AM
  Subject: [FlyRotary] Re: single rotor performance


  Sounds good Richard.  But what about RPM delta at full throttle =
between the two different runner lengths?  That is the acid test for HP =
increase (with a prop load).  You are in the best possible position to =
test different runner lengths with that single runner manifold.  I give =
a lot to see a performance curve plot of different runner lengths in =
increments of 1" between 8 and 24".


  I'm surprised you saw a significant difference in MP.  Where did you =
have the tap?  If it is in the runner I suspect you may be seeing =
velocity effects.  I know you are aware of the importance of dynamic and =
static pressure in this situation so I was wondering how you arrived at =
the total pressure.

  Also surprised that the long runner did not cause any idle problems =
when using a carb.  With the evaporative cooling in the runner, they =
sometimes freeze up and condensation of the mixture happens which can =
cause rough idle.  The 2000 rpm idle helps there I guess.

  Tracy


  On Wed, Nov 5, 2008 at 9:40 AM, Richard Sohn <res12@fairpoint.net> =
wrote:

    Another step in the right direction.

    In deciding which way to go with the intake for the single rotor, I =
ran two tests. The first one with a short 8" long intake runner, and a =
second one with a 24" runner.=20
    The results are certainly not surprising, however, I had to check =
the possible impact on idle characteristic.=20
    Except for a different idle mixture setting, I was not able to =
detect a difference in idle characteristics at 2000RPM. There is no need =
for lower idle with a 3.33 : 1 gear ratio. If for any reason I want to =
go lower with idle, I would have to increase the fly wheel inertia. With =
no load on the engine it idles down to 1300RPM with the 8" runner.=20
    The long runner also resulted in a 1" higher MAP over the short =
runner.

    The 24" runner as shown in the picture will in the final =
configuration be at least 3" longer, because the carb has to com lower =
than it is now.

    The engine config is 12A rotor and housing using 1 1/2" p-port.=20

    The HP calculation is based on a bsfc of .5 . This is probably =
conservative with EGT at 1700F and mixture ratio at 14.6 .

    Richard Sohn
    N2071U

    --
    Homepage:  http://www.flyrotary.com/
    Archive and UnSub:   =
http://mail.lancaironline.net:81/lists/flyrotary/List.html






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  No virus found in this incoming message.
  Checked by AVG - http://www.avg.com=20
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11/5/2008 7:17 AM

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Diso-8859-1">
<META content=3D"MSHTML 6.00.2900.5659" name=3DGENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>I think there are a few things that =
need=20
clarification. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>The lower RPM runs were not WOT! I just =
recorded=20
those on the way up to WOT, all at the same prop pitch. Meaning the only =

significant data point is at 6000RPM, which I consider about static. For =
that=20
reason, the power level at those lower RPM are more reflecting the prop =
power=20
demand than anything else.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>As to the RPM difference, It may have =
been 100 or=20
150 RPM higher on the&nbsp;long runner than on the short one(tach =
reading a bit=20
iffy). There is some thing else I ran into. All previous tests I ran =
with the=20
prop showed some intermittent prop noise, seemingly influenced by the =
wind=20
condition at testing time. This noise is very stady with the long =
runner. It is=20
acoustically so strong you think it is going to blow your brains out. I =
could=20
barely stand it until the fuel flow meter stabilized. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I have observed that phenomenon with =
the same type=20
or prop on the SOOB at static runups. It seems that the increased power =
produced=20
with the long runner is consumed by a sudden drag increase in the prop. =
This=20
prop may just not be suitable for that kind of tests. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I will do further tests with different =
prop=20
pitch,&nbsp;where the noise issue is one thing I want to find out=20
more.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I may have to look for another =
prop.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>The MP is measured at the same location =
in both=20
cases, about 1" from the rotor housing. The pressure is picked up =
through a .035=20
hole. I guess I should have said "MP" and not "MAP", sorry for=20
that.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>Generally I am not very inclined to do =
a lot more=20
basic performance tests since the engine is already producing way more =
power=20
than my test bed needs for flying. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>But that may change as I get further =
down the road.=20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>Richard Sohn<BR>N2071U</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<BLOCKQUOTE=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
  <A title=3Dtracy@rotaryaviation.com =
href=3D"mailto:tracy@rotaryaviation.com">Tracy=20
  Crook</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Dflyrotary@lancaironline.net=20
  href=3D"mailto:flyrotary@lancaironline.net">Rotary motors in =
aircraft</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Wednesday, November 05, =
2008 9:09=20
  AM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [FlyRotary] Re: single =
rotor=20
  performance</DIV>
  <DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2></FONT><FONT=20
  face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2></FONT><BR></DIV>
  <DIV>Sounds good Richard.&nbsp; But what about RPM delta at full =
throttle=20
  between the two different runner lengths?&nbsp; That is the acid test =
for HP=20
  increase (with a prop load).&nbsp; You are in the best possible =
position to=20
  test different runner lengths with that single runner manifold.&nbsp; =
I give a=20
  lot to see a performance curve plot of different runner lengths in =
increments=20
  of 1" between 8 and 24".</DIV>
  <DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2></FONT><FONT=20
  face=3DArial size=3D2></FONT><FONT face=3DArial size=3D2></FONT><FONT =
face=3DArial=20
  size=3D2></FONT><BR><BR>I'm surprised you saw a significant difference =
in=20
  MP.&nbsp; Where did you have the tap?&nbsp; If it is in the runner I =
suspect=20
  you may be seeing velocity effects.&nbsp; I know you are aware of the=20
  importance of dynamic and static pressure in this situation so I was =
wondering=20
  how you arrived at the total pressure.<BR><BR>Also surprised that the =
long=20
  runner did not cause any idle problems when using a carb.&nbsp; With =
the=20
  evaporative cooling in the runner, they sometimes freeze up and =
condensation=20
  of the mixture happens which can cause rough idle.&nbsp; The 2000 rpm =
idle=20
  helps there I guess.<BR><BR>Tracy<BR><BR></DIV>
  <DIV class=3Dgmail_quote>On Wed, Nov 5, 2008 at 9:40 AM, Richard Sohn =
<SPAN=20
  dir=3Dltr>&lt;<A=20
  href=3D"mailto:res12@fairpoint.net">res12@fairpoint.net</A>&gt;</SPAN> =

wrote:<BR>
  <BLOCKQUOTE class=3Dgmail_quote=20
  style=3D"PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: =
rgb(204,204,204) 1px solid">
    <DIV bgcolor=3D"#ffffff">
    <DIV><FONT face=3DArial size=3D2>
    <DIV><FONT face=3DArial size=3D2>Another step in the right=20
    direction.</FONT></DIV>
    <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
    <DIV><FONT face=3DArial size=3D2>In deciding which way to go with =
the intake for=20
    the single rotor, I ran two tests. The first one with a short 8" =
long intake=20
    runner, and a second one with a 24" runner. </FONT></DIV>
    <DIV><FONT face=3DArial size=3D2>The results are certainly not =
surprising,=20
    however, I had to check the possible impact on idle characteristic.=20
    </FONT></DIV>
    <DIV><FONT face=3DArial size=3D2>Except for a different idle mixture =
setting, I=20
    was not able to detect a difference in idle characteristics at =
2000RPM.=20
    There is no need for lower idle with a 3.33 : 1 gear ratio. If for =
any=20
    reason I want to go lower with idle, I would have to increase the =
fly wheel=20
    inertia. With no load on the engine it idles down to 1300RPM with =
the 8"=20
    runner. </FONT></DIV>
    <DIV><FONT face=3DArial size=3D2>The long runner also resulted in a =
1" higher=20
    MAP over the short runner.</FONT></DIV>
    <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
    <DIV><FONT face=3DArial size=3D2>The 24" runner as shown in the =
picture will in=20
    the final configuration be at least 3" longer, because the carb has =
to com=20
    lower than it is now.</FONT></DIV>
    <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
    <DIV><FONT face=3DArial size=3D2>The engine config is 12A rotor and =
housing=20
    using 1 1/2" p-port. </FONT></DIV>
    <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
    <DIV><FONT face=3DArial size=3D2>The HP calculation is based on a =
bsfc of .5 .=20
    This is probably conservative with EGT at 1700F and mixture ratio at =
14.6=20
    .</FONT></DIV>
    <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV><FONT =
color=3D#888888>
    <DIV><FONT face=3DArial size=3D2>Richard=20
    =
Sohn<BR>N2071U</FONT></DIV></FONT></FONT></DIV></DIV><BR>--<BR>Homepage: =

    &nbsp;<A href=3D"http://www.flyrotary.com/"=20
    target=3D_blank>http://www.flyrotary.com/</A><BR>Archive and UnSub: =
&nbsp; <A=20
    href=3D"http://mail.lancaironline.net:81/lists/flyrotary/List.html"=20
    =
target=3D_blank>http://mail.lancaironline.net:81/lists/flyrotary/List.htm=
l</A><BR><BR></BLOCKQUOTE></DIV><BR>
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